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IJSRK Internat ional Journal of Scient if ic Research in Knowledge

www.i jsrpub.com

July 2013

Volume 1, Issue 7

Pages 175 – 237

Table of Contents

Article Author(s) page

Evaluation of Ductility and Load Carrying Capacity in RC Beam-Column in Exterior Joints Enhanced with FRP

Alireza Mardookhpour 175

Synthesis and Characterization of Two New Oxo-centered Trinuclear Complexes of Manganese and Iron

Haman Tavakkoli, Arezoo Ghaemi, Fouad Mohave

182

Factors Influencing Anemia and Night Blindness among Children Less than Five Years Old (0 - 4.11 Years) in Khartoum State, Sudan

Samir Mohamed Ali Hassan Alredaisy, Haram Omer El Hag Saeed

189

Remediation of Tetrachloroethylene -Contaminated Soil with Zero Valent Iron Utilizing Electrokinetic Reactors

Maryam Taghizadeh, Daryoush Yousefi Kebria

202

Monitoring and Configuration of Energy Harvesting System Using WSN

Kodegandlu Venkatarayappa Narayanaswamy

212

Assessing Cracks in Reinforced Concrete Structure Using Acoustic Emission

Alireza Panjsetooni, Norazura Muhamad Bunnori, Tze Liang Lau

222

Time-Dependent Creep Analysis of Rotating Thick-Walled Cylindrical Pressure Vessels under Heat Flux

Mohammad Zamani Nejad, Mosayeb Davoudi Kashkoli

228

International Journal of Scientific Research in Knowledge (IJSRK), 1(7), pp. 175-181, 2013 Available online at http://www.ijsrpub.com/ijsrk

ISSN: 2322-4541; ©2013 IJSRPUB

http://dx.doi.org/10.12983/ijsrk-2013-p175-181

175

Full Length Research Paper

Evaluation of Ductility and Load Carrying Capacity in RC Beam-Column in Exterior

Joints Enhanced with FRP

Alireza Mardookhpour

Ph.D., Department of Civil Engineering, Islamic Azad University, Lahijan Branch, Iran

[email protected]

Received 18 April 2013; Accepted 21 May 2013

Abstract. One of the techniques of strengthening of the reinforced concrete (RC) structural members is through confinement

with a composite enclosure. This external confinement of concrete by high strength fiber reinforced polymer (FRP) composite

can significantly enhance the strength and ductility and will result in large energy absorption capacity of structural members.

An experimental investigation of the behavior of retrofitted FRP wrapped exterior beam-column joints under seismic

conditions is presented. Also, the experimental study on exterior beam-column joint of a multistory reinforced concrete

building under the seismic has been analyzed using ANSYS software. Two specimens were cast and tested to failure during the

present investigation. One is Control specimen test up to 70% of the ultimate load (without FRP), and another specimen test

up to 70% of the ultimate Load (with one layer of FRP). The results show about 18% has been obtained by retrofitting with

FRP sheets in load carrying capacity. Also an increase about 54% has been obtained by retrofitting with FRP sheets in

cumulative ductility.

Key words: FRP, cyclic loading, ANSYS software, beam-column exterior joints

1. INTRODUCTION

One of the modern methods in strengthening concrete

structures is utilizing fiber reinforced polymers (FRP)

bonded to concrete beams as strips made of carbon

fibers. The effect of FRP (Fiber Reinforced Polymers)

sheets on bending strength of beams is one of the

advantages of utilizing carbon fibers in concrete

structures. FRP materials have a number of favorable

characteristics such as ease, to install immunity to

corrosion, high strength, availability in sheets etc

(Appa Rao et al., 2008). Tensile Properties of the

Sprayed GFRP has been shown in Table 1 and Figure

1.The simplest way to strengthen such joints is to

attach FRP sheets in the joint region in two orthogonal

directions (HungJen and SiYing, 2009).

In RC buildings, portions of columns that are

common to beams at their intersections are called

beam-column joints. Under earthquake shaking, the

beams adjoining a joint are subjected to moments in

the same (clockwise or counterclockwise) direction

(Murthy et al., 2001). The dynamics of earth quake

loadings are 12 cycles in five stages .The loading is

applied gradually for forward direction with

3,6,9,12,15 KN respectively and 3,6,9,12,15 KN for

reverse direction. Under these moments, the top bars

in the beam-column joint are pulled in one direction

and the bottom ones in the opposite direction (Kolluru

and Subramaniam, 2007). These forces are balanced

by bond stress developed between concrete and steel

in the joint region. If the column is not wide enough

or if the strength of concrete in the joint is low, there

is insufficient grip of concrete on the steel bars (Tajari

and Esfehani, 2006).

In such circumstances, the bar slips inside the joint

region, and beams lose their capacity to carry load.

Further, under the action of the above pull-push forces

at top and bottom ends, joints undergo geometric

distortion; One diagonal length of the joint elongates

and the other compresses (Ali-Ahmad et al., 2007;

Murugesan and Thirugnanam, 2009). If the column

cross-sectional size is insufficient for satisfying

minimum bar ratio, the concrete in the joint develops

diagonal cracks (Tajari and Esfehani, 2006). Problems

of diagonal cracking and crushing of concrete in the

joint region can be controlled by two mean, namely

providing large column sizes and providing closely

spaced closed-loop steel ties around column bars in

the joint region (Sayed and Soleimani, 2009). The ties

hold together the concrete in the joint and also resist

shear force, thereby reducing the cracking and

crushing of concrete (Murugesan and Thirugnanam,

2009). One of the newest methods for retrofitting joint

region of beam-column, to increase shear strength of

RC structures under cyclic loading is utilizing FRP

sheets (Thirugnanam, 2007; Tsonos et al., 1992).

mailto:[email protected]

Mardookhpour


176

2. MATERIALS AND METHODS

The experimental study exterior beam-column joint of

a reinforced concrete structure under the seismic

circumstance has been analyzed using ANSYS

software. Mechanical properties of GFRP sheets are

presented in Table 1. Also the stress – strain

relationship is sketched in Figure 1.

Table 1: Tensile Properties of the Sprayed GFRP

unit value Tensile Properties

M Pa 69 Ultimate Tensile Strength

M Pa 14000 Tensile Modulus

% 0.63 Ultimate Rupture Strain

Fig. 1: Stress – strain diagram of GFRP sheets

For testing model the dimension of beam was 120

X 170 mm with out slab thickness and beam length of

450mm and that column size was 120 X 230 mm.

Height of the column was 600mm.Figure (2.a-1.b)

shows the details of beam- column joints. The basis

for this model and reinforcements is satisfying

minimum bar ratio and flexibility in joints.

The reinforcement cages were placed in the moulds

and cover between cage and form provided was 20

mm. The concrete mixture design has been shown in

Table 2.

Table 2: Concrete mixture design (kg / m3)

Coarse aggregate sand cement water

750 1000 300 160

The concrete was placed into the mould

immediately after mixing and well compacted.

Control cubes and cylinders were prepared for all the

mixes along with concreting. The test specimens

cubes were remolded at the end of 24 hours of casting.

They were marked identifications. They are cured in

water for 28 days. After 28 days of curing the

specimen was dried in air and white washed according

to ISIS. A hydraulic jack was used to apply the axial load

for column. To record the load precisely a proving

ring was used. The load is applied forward and

reverses cyclic and deflection measured by using

LVDT (Figure 3).Linear variable differential

transformer (LVDT) is a type of electrical transformer

used for measuring linear and rotary position and

displacement. The LVDT converts a position or linear

displacement from a mechanical reference (zero, or

null position) into a proportional electrical signal

containing phase (for direction) and amplitude (for

distance) information. After loading the deflection of

the specimens the strains at the end- spans are

measured by gauge. Also, the strain of concrete at the

level of the tensile and compressive reinforcing bars

and the strain of GFRP sheets at the end- span of

beam are measured by gauge according to Figure 3.

International Journal of Scientific Research in Knowledge (IJSRK), 1(7), pp. 175-181, 2013

177

Fig. 2: a. casting the joint

Fig. 2: b. ductile detailing of beam -column joint

Fig. 3: Measuring instruments

The deflection was measured at the beam free end

tip. The loading is applied gradually for forward

direction with 3,6,9,12,15 KN respectively and

3,6,9,12,15 KN for reverse direction (Figure 4 a, 4 b).

Mardookhpour


178

Fig. 4: b Test Setup for Cyclic Loading for Control Specimen

The Exterior beam column joint specimen named

as SL1 (Single Layer) was tested subject to quasistatic

cyclic loading simulating earthquake loads (Figure 4-

1, 4-2). The Load was applied by using screw jack

under 5 cycles. The beam-column joint was gradually

loaded by increasing the load level during each cycle

on the column head (Tang and Saadatmanesh, 2005).

The load sequence consists of 3kN, 6kN, 9kN and up

to 70% ultimate load. The deflection measured at tip

during the cycle of loading, as the load level was

increased in each cycle.

Fig. 4: a Load setup for the retrofitted specimen

3. RESULTS AND DISCUSSION

Experimental results are compared with finite

elements model (FEM) in ANSYS software. The

70% of ultimate load carrying capacity of the joint

was 17.0 kN in control specimen. In other words, the

first crack was witnessed during 4 th cycle at the load

level of 17.0 kN. The maximum stresses are occurred

at the junction for the ultimate loading. As the load

level was increased, further cracks were developed in

other portions. Cumulative ductility of joint for

control specimen has been shown in Figure 5.


179

0

5

10

15

20

25

30

35

40

0 5 10 15

Load Cycles

Co

mu

lati

ve D

ucti

lity

(m

m)

Retrofitted Specimens

Control specimens

Fig. 5: Comulative ductility VS load cycles for Control Specimen

In the next series of experiments, the GFRP

wrapped specimen was subjected to quasistatic cyclic

loading simulating earthquake loads. The history of

load sequence followed for the test was presented in

Figure 6.

Fig. 6: Load Vs Deflection curve for retrofitted specimen

The loading is applied gradually for forward

direction with 3,6,9,12,15 KN respectively and

3,6,9,12,15 KN for reverse direction. The load was

applied by using screw jack Totally 12 cycles were

imposed. The 70% of ultimate load carrying capacity

of the one single layer (SL1) specimen was 20.0kN

recorded at 5 th cycle. Figure 5 shows the ductility-

load curve for retrofitted specimen. According to

Figure 5, an increase about 54% has been obtained by

retrofitting with FRP sheets in cumulative ductility. In

Control specimens the cumulative ductility reached

about 24 mm whereas in retrofitted specimens the

cumulative ductility has been increased up to 37 mm.

Also, the load carrying capacity in Control specimens

has been about 13.5 kN, but the load carrying capacity

in retrofitted specimens increased up to 15 kN which

refers an increase about 18 % has been obtained by

utilizing GFRP at the joint region.

4. CONCLUSION

The structural behavior of RCC beam column joint

exterior type has been studied analytically by using

standard software packages ANSYS software. The

load deformation characteristics and load carrying

capacity improved to large extent in the case of the

Mardookhpour


180

retrofitted specimen over the control specimen in test

presented work. The results show, the load carrying

capacity has been increased about 18% by retrofitting

with FRP sheets. Also an increase about 54% has been

obtained by retrofitting with FRP sheets in cumulative

ductility.

REFERENCES

Ali-Ahmad M, Subramaniam KV, Ghosn M (2007).

Analysis of Instability in FRP Concrete Shear

Debonding for Beam Strengthening

Applications. Journal of Engineering

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R (2008). Performance of nonseismically

designed RC beam column joints strengthened

by various schemes subjected to seismic loads.

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Exterior Beam-Column Joints with Different

Anchorage Methods, The ACI structural

Journal, Title No.106S32.

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structures with externally-Bounded fiber

reinforced polymers. Design manual. No 4.

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(2001).Anchorage Details and Joint Design in

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Behavior of Steel Fiber Reinforced Concrete

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Innovations in civil Engineering. Mepco

Schlenk Engineering college, Sivakasi , 27-33.

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181

Dr. Alireza Mardookhpour has Ph.D. in Civil Engineering. He is Assistant Professor in department of

civil and water engineering, manager of civil engineering, Islamic Azad University, Lahijan Branch,

Iran. He has 81 papers in ISI and scientific research journals.


ISSN: 2322-4541; ©2013 IJSRPUB


182


Synthesis and Characterization of Two New Oxo-centered Trinuclear Complexes of

Manganese and Iron

Haman Tavakkoli*, Arezoo Ghaemi, Fouad Mohave

Department of Chemistry, Science and Research Branch, Islamic Azad University, Khouzestan, Iran

*Corresponding author: [email protected]

Received 1 May 2013; Accepted 3 June 2013

Abstract. Two new oxo-centered trinuclear complexes, one of them a mixed-valence complex [Mn2MnO(CCl3CO2)6(Py)3] (1)

and the other, mixed-metal complex of [Fe2MnO(CCl3CO2)6(H2O)3].NO3 (2) were synthesized by the direct reaction between

metal nitrates and trichloroacetic acid. These complexes were characterized by elemental analyses (CHN), atomic absorption

spectroscopy and spectral (IR, electronic) studies. These are new types of oxo-bridged mixed-metal complexes in which the

carboxylate ligand is trichloroacetic acid. The UV spectra of the complexes exhibited strong bands in the region 213 and 257

nm which are related to the (π → π*) and (n → π*) transitions of the pyridine and H2O ligands, respectively. The IR spectra of

these compounds showed two strong stretching vibrations bands, indicating a bridging coordination mode of the carboxylic

group of the ligand in the complexes.

Keywords: oxo-centered; trinuclear complexes; carboxylic ligand; IR spectra.

1. INTRODUCTION

Transition-metal carboxylate chemistry has played a

key role in the conceptual development of modern

inorganic chemistry (Kim and Cho, 2004). The

current interest in the trinuclear, oxo-centered metal

carboxylate assemblies of the general composition

[M3O(OOCR)6L3]+ (where M= trivalent 3-d metal,

RCOO=carboxylic acid (R = CH3, Ph, etc) L=

monodentate ligand) is due to these complexes have

served as important models to test theories of

magnetic and electronic coupling between metal ions

(Beattie et al., 2003 and Gavrilenko et al., 2002). They

are particularly valuable as frame works for

systematically studying metal-metal interactions in

clusters and constitute an important class of

compounds in transition metal chemistry. They have

been characterized with a wide variety of first-row

and heavier transition metals, with mixed-metal

(Blake et al., 1998) and mixed-valency combinations

(Wu et al., 1998).

Electron transfer interactions, and subtle

distortions from regular structures, can be detected by

their effects on molecular vibrations. These are

valuable precursors for the synthesis of higher

nuclearity clusters exhibiting interesting magnetic

properties. Surprisingly, little attention has been paid

to the consideration of substitution properties, with

only a few reports of comparative studies regarding

the redox properties when the terminal ligand L

changes. There is interest in establishing how

substitution in the Carboxylate Bridge affects the

liability of the terminal ligand and the redox potential

of the metal centers. These carboxylate complexes are

of additional interest when the carboxylate is

unsaturated, because there is a potential scope for

further polymerization in the solid state by cross-

linking of the substituents (Chavan et al., 2001 and

Maragh et al., 2005). Trinuclear μ3,-oxo-bridged iron

carboxylate complexes have been studied in great

detail (Sorai et al., 1986 and Woehler et al., 1986),

whereas analogous mixed-valence manganese-

carboxylate complexes have been the object of only

limited investigation to date. Each carboxylate anion

spans two metal centers at the periphery of the

[M3(μ3-O)]6+

core, while the neutral monodentate

ligands occupy the remaining coordination sites on

each metal center, and as a result the coordination

around the metal center is approximately octahedral

(Fig.1)

In previous studies, we reported fabrication of

some trinuclear oxo-centered complexes with

saturated and unsaturated carboxylate ligands

(Yazdanbakhsh et al., 2010 and Tavakkoli et al., 2011

and Yazdanbakhsh et al., 2009). In this paper, the

syntheses and characterization of mixed-valence and

mixed-metal clusters are reported. These are,

however, limited to clusters coordinated by relatively

small organic ligands.

Tavakkoli et al.


183

2. EXPERIMENTAL

2.1. Materials

All starting materials, except (N-n-Bu4MnO4), used in

this study were analytical grade and purchased from

Merck.

Fig. 1: Schematic representation of the oxo-centered trinuclear clusters structure [M3O(RCOO)6(L)3]

z

N-n-Bu4MnO4; This material was prepared, as

outlined in the literature (Yazdanbakhsh et al., 2007),

by mixing aqueous solutions of KMnO4, (5.00 g, 31.6

mmol) and N-n-Bu4Br (12.00 g, 37.2 mmol) with

vigorous stirring to give a total volume of ca. 200 ml.

The immediate purple precipitate was collected by

filtration, washed thoroughly with distilled water and

diethyl ether and dried in vacuum at ambient

temperature: yield > 90%.

The C, H and N analyses were realized on a Thermo

Finnigan Flash model EA1112 elemental analyzer.

The atomic absorption analyses were performed on a

Shimadzu model AA-670 atomic absorption

spectrometer. The IR spectra of KBr discs (600–4000

cm-1

) were recorded on a Buck 500 spectrometer. The

electronic spectra were registered in the range of 200–

600 nm on a Perkin-Elmer 1600 spectrometer.

Preparation of [Mn2MnO(CCl3CO2)6(Py)3]

N-n-Bu4Br (12 g, 37.2 mmol) was added to an

aqueous solution of KMnO4 (5 g, 31.6 mmol) under

vigorous stirring. The immediately formed purple

precipitate was collected by filtration, washed

thoroughly with distilled water and diethyl ether and

dried in vacuo at room temperature. Then

Mn(OOCMe)2.4H2O (10 mmol, 2.5 g) and

trichloroacetic acid (54 mmol, 8.83 g) were dissolved

in a solvent mixture comprising pyridine (7 ml) and

absolute ethanol (15 ml). The resulting solution was

stirred while solid N-n-Bu4MnO4 (3.5 mmol, 1.25 g)

was added in small portions and stirred to give a dark

brown homogeneous solution. This solution was

allowed to stand undisturbed for 48 h and the resulting

large octahedral-shaped crystals were collected by

filtration, washed with pyridine and dried in vacuum.

(Yield: 72%), m.p.: 185˚C, Anal. Calc. for

C27H15Cl18Mn3N3O13: C, 23.26; H, 1.07; N, 3.01; Mn,

11.84%. Found: C, 22.96; H, 1.15; N, 3.11; Mn,

11.65%.

Preparation of [Fe2MnO(CCl3CO2)6(H2O)3].NO3

A mixture of Fe(NO3)3.9H2O (1.08 g, 2.68 mmol) and

Mn(NO3)2.4H2O (0.34 g, 1.34 mmol) was dissolved in

25 ml deionezed water and was refluxed for 10 min.

Then, NaCCl3CO2 (2.22 g, 12 mmol) was added and

the reflux continued for 5 h. The resulting brown

solution was allowed to cool and stored for 2 days at

20 °C. The black crystals were filtered off, washed

copiously with Et2O and dried in vacuum. (Yield:

85%), m.p.: 275˚C, Anal. Calc. for

C12H6Cl18Fe2MnNO22: C, 10.89; H, 0.45; N, 1.06; Fe,

8.47; Mn, 4.16%. Found: C, 10.64; H, 0.62; N, 1.14;

Fe, 8.85; Mn, 4.39%.


3.1. IR Spectroscopy

The IR spectra of these complexs are shown in Fig. 2

that indicate the presence of carboxylate, H2O and

M2MO groups. The observed vibrational

frequencies υasym(COO) and υsym(COO) for the


184

carboxylate ligand support the presence of bridging

coordinated carboxylates in all the complexes. For the

mixed-metal complexes, it appears from the

carboxylate stretching frequencies that all six ligands

are approximately equivalent and they are best

represented as bidentate bridges. For a new series of

trinuclear mixed metal complexes, Cannon assigned

the IR spectra and identified the vibrational modes of

the central M3O core (Baranwal et al., 2009). He

found that the reduction in site geometry from D3h to

C2v lifted the degeneracy of the asymmetric M3O

stretches and two bands were seen. These spectra

indicate a single pair of carboxylate stretching

vibrations at 1601 and 1425 cm-1

for (1), 1615 and

1430 cm-1

for (2) assigned to υasym(COO) and

υsym(COO), respectively. The difference (Δυ =

υasym(COO) –υsym(COO)) is 176 and 185 cm–1

. In the

IR spectrum of complex 2, the characteristic vibration

frequencies for H2O groups appear at ~3500–3600 cm-

1. For identification of the metal-oxygen bonds of

M3O group, IR spectra in the range of 800-400 cm-1

were used (Boudalis et al., 2002). The band observed

for asymmetric vibration associated with the M2M'O

unit splits into two components, A1 and B2 (Cannon

and White, 1988) .These spectra show the

characteristic bands for the valence oscillations

υas(Fe2MnO) in the region 565 cm-1

(A1) and 420 cm-1

(B2) and υas(Mn3O) is observed at 580 cm-1

. All data

of IR spectroscopy for these compounds are given in

Table 1.

Table 1: Selected IR bands (cm-1

) for complexes

Compound asym (COO) sym (COO) (M3O) (C-H) (C-Cl) (O-H)

1 1601 1425 580 3036 824

2 1615 1430 420-565 2970 816 3570

Fig. 2: IR spectra of [Mn2Mn(O)(CCl3COO)6(py)3] (a) and [Fe2Mn(O)(CCl3COO)6(H2O)3].NO3 (b) (KBr pellet)

Tavakkoli et al.


185

3.2. Electronic spectroscopy

The electronic spectra of the trinuclear complexes can

be interpreted to a good approximation in terms of the

individual metal ions, together with ligand-metal

charge transfer transitions. The electronic spectra of

the complexes were recorded in the range of 200-600

nm in dichloromethane solution. The spectra of the

oxo-centered complexes 1 and 2 show the

characteristic bands provided by both metal ions. The

UV spectra of the complex 1 and 2 (Fig.3) exhibited a

strong bands in the region 257 and 213 nm which is

related to the (π → π*) transitions of the pyridine (Py)

ligand (Chen et al., 2005) and (n → π*) transition of

the water ligand.

The Vis spectra for complex 1 and 2 are shown in

Fig. 4. As is obvious in this Figure, broad band in the

region 480 nm, which can be assigned to the transition

from 5Eg to

5T2g, should be attributed to the existence

of Mn(III)

(d4) ion in these complexes. Obtained data

can be assigned and characterized based on other

literature (Mizoguchi et al., 1999).

Fig. 3: UV spectra of the [Mn2MnO(CCl3CO2)6(Py)3] (a) and [Fe2MnO(CCl3CO2)6(H2O)3].NO3 (b)

4. CONCLUSION

Two new Oxo-centered trinuclear complexes with the

general formula [M2M'O(CCl3COO)6(L)3] where M =

Mn, M' = Mn, L = py (1); M = Fe, M' = Mn, L = H2O

(2) were prepared and studied by elemental analysis

(CHN), electronic and infrared spectroscopy and

atomic absorption spectroscopy. All compounds have

a similar μ3-oxo structure. The IR investigations of

these compounds show intensive absorption bands,

which are assigned to υasym(COO) and υsym(COO)

vibrations. Furthermore, the three metal ions are

bound to a central oxygen atom and adjacent metal

ions are bridged by two carboxylate ligands. In

addition, for mixed metal complex 2, the atomic

absorption data show a statistical 2:1 disorder of iron

and manganese atoms, respectively.


186

Fig. 4: Vis spectra of the [Mn2MnO(CCl3CO2)6(Py)3] (a) and [Fe2MnO(CCl3CO2)6(H2O)3].NO3 (b)

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188

Dr. Haman Tavakkoli is an assistant professor in inorganic chemistry in Islamic Azad University,

Khouzestan Science and Research Branch, Iran. He received his M.Sc and Ph.D degree in inorganic

chemistry from Ferdowsi University of Mashhad, Iran in 2007 and 2012, respectively. He has published

14 refereed articles in valid ISI journals and 10 scientific articles in conference proceedings. Dr.

Tavakkoli’s fields of expertise are in coordination chemistry, nanomaterials chemistry and physics and

environmental chemistry.

Dr. Arezoo Ghaemi obtained her Bachelor’s degree from the Ferdowsi University of Mashhad, Iran in

chemistry in 2004. She later bagged her Master’s and Doctorate degrees in Analytical chemistry from

Ferdowsi University of Mashhad, Iran in 2006 and 2012, respectively. She has graduated with first

grade in Ph.D degree. At present, Dr. Ghaemi is an assistant professor in analytical chemistry in Islamic

Azad University, Khuzestan Science and Research Branch, Iran. She has published numerous articles in

ISI journals and conference proceedings.

Fouad Mohave is a MSc student in Organic Chemistry Science and Research Branch, Islamic Azad

University, Khouzestan, Iran.


ISSN: 2322-4541; ©2013 IJSRPUB


189


Factors Influencing Anemia and Night Blindness among Children Less than Five

Years Old (0 - 4.11 Years) in Khartoum State, Sudan

Samir Mohamed Ali Hassan Alredaisy1, Haram Omer El Hag Saeed

2

1Faculty of Education, University of Khartoum, Khartoum Omdurman 406 Sudan 2Rufaa Nutrition and Maternity Office, Ministry of Health, Gezira state, Sudan

*Corresponding Author: [email protected]

Received 24 April 2013; Accepted 5 June 2013

Abstract. This study investigated factors influencing nutritional status of children less than five years old suffering anemia and

night blindness in Khartoum State. Sample size was 138 children determined by 10% rate of prevalence of nutritional

deficiency diseases among children living in Khartoum State. In addition, testing hemoglobin and anthropometric

measurements were done. Results depicted that, illiteracy was prevailing, and household monthly income averaged 100 USD.

Symptoms of anemia included loss of appetite (8777%), paleness (9375%), and eating clay (29%), while for night blindness

they were xerophthalmia (20%); Pinot spots (52%); karatomalacia (12%), and Cornea ulceration (4%). Children suffering these

two diseases had hemoglobin concentration below 60% standard, indicated to Iron deficiency anemia and cute malnutrition

constitute 63% of the cases. Females are less malnourished compared to males. Significant relationship exists between

household monthly income and number of meals per day taken by a child (P=0 .0003); and between nutritional status of

children and number of meals taken by a child per day (P=0 .003); and between household monthly income and frequency of

daily intake of energy, protein, iron by a child (0.04; 0.01; 0.07 respectively). Nutritional status of pregnant women and

nutritional status of the family are significantly correlated (P= 0.0056); and hemoglobin and intake of animal and plant protein

is significant correlated (P= 0.03 and 0.01 respectively). Big family size of children suffering anemia and night blindness had

reduced their share of energy, protein, iron and vitamin A. The authors suggested some recommendations to alleviate these two

diseases in Khartoum State.

Key words: anemia, night blindness, malnutrition, poverty, illiteracy, lactation, low food quality, Khartoum State

1. INTRODUCTION

Nutrition deficiency diseases are worldwide

spreading. In Sudan, one child out of ten dies before

completing five years due to these diseases (UNICEF,

2008). Malnutrition due to micro nutrients deficiency

(hidden hunger) represents the most prevailing form

of nutrition deficiency diseases where more than two

billions are suffering from it in the world; in addition

to more than 250,000 children are affected by night

blindness every year and more than half of these

children dies approximately (UNICEF, 2008). In

Sudan, the estimated rate of prevalence of hidden

hunger is 4.8% while the rate of anemia (iron

deficiency anemia) for children less than five years

old is about 55.1% (National Ministry of Health,

2008; World Health Organization, 2009). In

Khartoum State, anemia due to Iron deficiency is

distributed as 76% in Khartoum town, 75.3% in

Khartoum north town, and 23.9% in Omdurman town

(National Ministry of Health, 2008; World Health

Organization, 2009). However, nutritional deficiency

diseases as cause of death during early childhood,

have contributed around 51% among overall causes of

death during this period (UNICEF, 2008).

Areas nutritionally insecure in Sudan include rural

areas of low crop and animal production; areas of low

purchasing power and education and knowledge; and

areas of low access to health facilities, in addition to

areas with low access to water especially during dry

season, vulnerable residents who were indirectly

affected by the influx of internally displaced

population in their communities and returnees

numbering 4 million internally displaced population

and 600,000 refugees almost all from south Sudan

(FAO/WFP, 2006; Cambrez et al., 1998). Nutrition

insecurity leads to protein – energy malnutrition.

Nutrition status is measured directly by dietary

surveys, biochemical data, and clinical examination

methods. While food adequacy is necessary for a

household to achieve nutrition security, it is not in

itself sufficient. This is because some other key

contributors to good nutrition are also important, such

as poverty reduction, female education and a healthy

environment. However, some researchers view

poverty as the main cause of malnutrition while some

others believe in malnutrition eradication without

reduction in poverty pointing to well nourished

children living in very poor households. Female

education is positively correlated with reduction in

Alredaisy and Saeed

Factors Influencing Anemia and Night Blindness among Children Less than Five Years Old (0 - 4.11 Years) in

Khartoum State, Sudan

190

infant mortality rate (UNICEF, 1990; Brahman,

1988). Environmental health largely determines

nutritional status either through infections, depletion

of nutrients and illnesses or vice versa (United Nation

University, 1979; Osmani, 1997; Biesel, 1984).

The purpose of this research is to investigate

factors influencing nutritional status of children

suffering anemia and night blindness in Khartoum

State and to suggest some recommendations to reduce

the incidence of these two diseases.


2.1. THE STUDY AREA

Khartoum States consists of the three towns of

Khartoum, Khartoum north and Omdurman (Fig.1).

Rate of population increase in Greater Khartoum was

4.92% in 1956, 7.76% in 1973, 8.75% in 1983, and

13.7% in 1993 (MFEP 1956–1993). The number of

persons per square kilometer was 55.6 persons in

1973, 85.5 in 1983 and 169 in 1993. In addition

Khartoum state accepted 39% of internal migration of

the country in 1983 and 45% in 1993 (MFEP 1956 –

1993). This population increase is reflected in the

expansion of informal squatter areas (El Bushra,

1995) and consequently higher demand for public

services.

Fig. 1: location of the three hospitals under study in Khartoum State

2.2. Data collection

The fieldwork took place in February 2009 through to

February 2012 in central specialized children hospitals

in each of the three towns, including Ga’far Bin Oaf

Hospital in Khartoum, Child Emergency Outpatient of

Omdurman Hospital, and Ahmad Grasim Hospital in

Khartoum north. A questionnaire was designed to

collect relevant nutritional data of children suffering

anemia and night blindness, as well as clinical data on

symptoms of anaemia and night blindness. To

estimate the sample size, based on 10% rate of

prevalence of nutritional deficiency diseases in

Khartoum State (Ministry of Health Khartoum

State,2009), the formula provided by Ministry of

Health, Khartoum State 2009, was used below:

n = sample size; Z = 1.96; P = prevalence

rate of nutritional deficiency diseases; q = 1 – P; d

= 0.05

The 10% prevalence, )96.1(n e rate of

nutritional deficiency diseases in Khartoum State is

used to get q which gave 138 individuals, as follows:


191

n= (1.96)2 x 0.1(1-0.1)

(0.05)2

=

= 138

To determine the share of each Hospital from this

sample size, the equation of distribution in proportion

to size of population (children suffering nutritional

deficiency diseases) in each hospital is used, as

follows:

Cases of malnutrition in Khartoum (15628) = = 32%

Cases of malnutrition in Khartoum north (12602) = = 26%

Cases of malnutrition in Omdurman (20773) = = 42%

The total cases of malnutrition in Khartoum State = 49003; The share of each town (hospital) of the sample size

is determined as:

Khartoum = = 44

Khartoum north = = 36

Omdurman = =58

Before conducting the fieldwork, children

suffering anemia and night blindness were determined

by testing blood samples which was done by

Technicians working in each of the three hospitals, as

well as one of the authors. Symptoms of anemia and

night blindness were specified by Doctors during their

routine rounds in the hospital. Following that, the

questionnaires were filled with mothers of the sick

children whom were chosen purposively.

Hemoglobin measurement was done by Colorimeter,

by taking 20 micro millimeter of the blood of the 138

sick children in a test tube, and 4 milliliter of

Drabakin was added with 14.8 15 gram/deciliter

concentration and fully mixed, left for five minutes to

be read by Colorimeter. This gave that: Hemoglobin

gm/Deciliter X 6.8 (constant factor) = Hemoglobin %

Anthropometric measurements were done using

Salter’s scale to measure weight for age for all the 138

children to determine their nutritional status, where

the nutritional status index of weight for age is a quick

and accurate method to determine the nutritional

status of children less than five years old.

The evaluation of the nutritional status of children

less than five years old was done using tables of

estimation of rate by age – group which is published

by World Health Organization. The most indices used

to measure body to estimate nutritional status is

weight for age index. Measurement of weight is used

into observing gradual growth in body volume and

organs and helps into detection of early malnutrition.

Daily food weight intake was carried out using

electronic scale which weights for 3 kilograms. To

determine average of energy, protein, iron and

Vitamin consumed relative to the size of the

household. Children under study were divided into

age groups including less than one year, 1-3 years,

and 4- 4.11 years; This classification facilitates

comparison between food consumption according to

age groups of children less than five years old.

Nutrients intake were calculated using food

20773 ×100

49003

32 ×138

100

26 ×138

100

42 ×138

100

12602 ×100

49003

15628 ×100

49003

Alredaisy and Saeed



192

composition tables for population in Sudan, provided

by Sukar (1985). Conditions for rejection included all

children transferred from other States of Sudan

hospitals during fieldwork, and the study was

restricted to those who live permanently in Khartoum

State during the time of fieldwork.

Traditional porridge is made by boiling cereals

(Dura or Dukhn), and usually taken with sauce or

milk. Sauce is a mixture of vegetables, meat, oil, and

spices. In addition, cereals are fermented and cooked

to produce traditional bread (Kisra).

3. RESULTS

3.1. Socioeconomic characteristics

The results of the fieldwork depicted that 94.2% of the

mothers interviewed were married, 4.3% widowed,

and 1.4% divorced. The age structure of the

households depicts that, the age group of children less

than one year old represents 6.1%, and the age group

1-3 years represents 18.7%, while the age group 4-6

years represents 13.0%. They collectively represented

37.8% of the total number of the members of

households. The remaining percentage is distributed

among the other age groups where the age group 29+

holds 24.5% of the total number of members of

households. The population is young, and its pyramid

would be flat at the bottom and had hard tip on top.

Concerning level of education of mothers and fathers

of the sick children, results revealed dominance of

religious education by 45% among mothers and 23%

among fathers, and 35 % of mothers had completed

basic school compared to 40% among fathers, while

11% of fathers had completed secondary school

compared to 3% for mothers. Generally, fathers are

more educated than mothers. Religious education is a

form of informal education and does not qualify for

good reading and arithmetic.

The majority of the heads of the households

worked in the informal sector (43.5%), followed by

those who work as traders (8.7%), then government

employees (6.5%), while those who worked as

farmers and car drivers have equal percent (6%). This

reflected educational qualification of the interviewees

who were incompetent to compete for higher carriers,

and therefore involved into the daily paid wages

informal sector. However, 96.4% of the mothers

interviewed were housewives, and only 3.6% of them

got involved into informal sector. The average

monthly income among those who work in the

informal sector is 450 Sudanese Guinea (SDG), while

traders can get as high as 700 SDG, government

employees 350 SDG and car drivers 600 SDG. They

collectively give monthly average income of 563

SDG. This equals almost 100 USD per month or 3.3

USD per day to categorize them as urban poor. The

majority of the households (87.7%) did not have an

additional income or remittances from their relatives

outside Sudan, while 12.3% have additional monthly

income that on average is 225 Sudanese Guinea ( 38

USD).

The majority of the houses of the interviewees had

traditional pit latrines (82.6%), shared pit latrines with

neighbors (13.8%) and modern sewerage system

represented very low percentage (1.4%). The highest

percent of them have no bathroom (42.0%) and

depend on water vendors to get drinking water

(donkey carts) by 47.8%, followed by those who have

piped water supply (43.5%), while some others

depend on communal water pipes (8.7% ). The

majority of the houses have one room (42.0%),

followed by two rooms (31.2%), then three (15.2%)

and lastly four rooms (11.6%). These rooms range in

area where small rooms 12 m2 represents the highest

percentage (59.4%), followed by 16 m2 (38.4%), and

lastly 9 m2 (2.2%). They depend on natural ventilation

(73.9%), and range in number of windows per room

where, 4 windows dominated (43.5%), followed by

three windows (33.3%), and 2 windows (16.7%) and

one window (6.5%).

3.2. Symptoms of anemia and night blindness

Physical symptoms of anemia are loss of appetite

(8777%), paleness (9375%), and fatigue, eating clay

(29%) and eating snow (279%). The symptoms of

night blindness are night blindness (12%);

xerophthalmia (20%); Pinot spots (52%);

karatomalacia (12%), and Cornea ulceration (4%).

Hemoglobin measurement for children suffering night

blindness (Table1) revealed that children aged 1-3

years old had less hemoglobin concentration

compared to those aged less than one year. Table 1

also revealed that children aged 3-5 years old who had

equal concentration of hemoglobin. This means that

children aged 1-3 year old sufferd Iron deficiency

anemia compared to the two other groups. This

contrasted anemic children, where children aged 1-3

and 3-5 years old almost had equal concentration of

hemoglobin which exceeds that for children aged less

than one year old. This means that, children <1 year

old were more anemic compared to those aged 1-3,

and 3-5 years old.

The general striking feature of distribution of night

blindness and anemia among these three age groups

was that, each age group had acquired ⅓ of incidence

of a disease and the differences might be quite minor.

The distribution of children suffering night blindness

by sex by percent of hemoglobin (Table 1) depicted

that males had higher level compared to females. This

could be also seen for anemia. Children suffered


193

anemia and night blindness distributed among

different age groups had very low percent of

hemoglobin below 60% standard, confirming for

prevalence of Iron deficiency anemia.

Table 1: Hemoglobin measurement (%) among children suffering Night blindness and Anemia by Age’s sex

Age / sex Night blindness Anemia

frequency % frequency %

<1 year 3 37 31 32.2

1-3years 18 34.8 73 38.8

3-5 years 4 37 9 39.1

Males 60 43.5 15 10.9

Female 53 38.4 10 7.2

Total 113 81.9 25 18.1

3.3. Levels of Iron deficiency malnutrition

Table 2 depicts Iron deficiency malnutrition in

Khartoum state. Acute Iron deficiency malnutrition

prevails with significant difference than the other

three levels of this type of malnutrition shown in the

table. The difference between normal and simple

levels of Iron deficiency malnutrition is quite small.

Acute Iron deficiency malnutrition is a reflection of

low nutritional status which makes children

vulnerable to childhood diseases. The distribution of

rate of Iron deficiency malnutrition by age groups of

these children suffering these two types of diseases

(Table 3), identified the highest rate among those aged

1-3 year old, followed by <1 year old and lastly by

those aged 3-5 years old. This means that acute

malnutrition remarkably prevails among children aged

1-3 year old, and significantly differs than the other

two age groups, and furthermore, the difference

between children aged <1 year old and children aged

3-5 years old is more than doubled. The distribution of

malnutrition by sex by age distinguishes males first

and then females. Females and males aged 1-3 years

suffered most. However, females are generally less

malnourished than males with difference of 8.6%

between them (Table 3).

Table 2: Iron deficiency malnutrition of children <5 years in Khartoum State

Iron deficiency malnutrition frequency %

Normal 11 8.0

Simple 13 9.4

Medium 27 19.6

Acute 87 63.0

Total 138 100.0

Note: These levels were determined according to weight for age of children suffering these two diseases in Khartoum State.

3.4. Type of food during pregnancy and lactation

Table 4 depicts types of type of food during

pregnancy and lactation. During pregnancy, mothers

used to consume vegetables, fruits, milk, cereals,

meat, and legumes abundantly. They also depended

on porridge with sauce; salad and yogurt which are

connected with likes and dislikes of pregnant women.

Lactating mothers largely depended on vegetables,

legumes, meat, cereals, milk, and fruits + sweet

porridge which are nutritionally valuable providing

protein, energy, iron, minerals, and vitamins. There is

no noticeable difference in food types during

pregnancy and lactation, except the introduction of

sweet porridge. Sweet porridge is a mixture of cereals,

sugar, oil, and ghee which activates producing much

milk for lactating mothers. Table 5 depicts that, the majority of mothers did

not take preventive or curative doses of Vitamin A

during pregnancy. This situation is somehow reversed

concerning Iron and Fevol. Folic acid recorded the

worst position among these four protective elements.

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194

Table 3: Iron deficiency malnutrition by sex / age

Table 4: Types of foods during pregnancy and lactation (%)

Types of foods Pregnancy (%) Lactation (%)

Porridge with sauce 20.3 0.0

Salad 10.9 0.0

Salad with yogurt 9.4 0.0

Vegetables, legumes, meat, cereals, milk, and fruits 56.4 18.1

Vegetables, legumes, meat, cereals, milk, and fruits+ sweet porridge 0.0 81.9

Total 100 100

Table 5: Ante-Natal Drugs Given to Mothers of Night blindness and Anemic Children in Khartoum State

3.5. Food type of children suffering anemia and

night blindness

The majority of households depend on fathers (63.8%)

for food provisioning, while few households depend

on mothers (10.1%), or relatives (26.1%). The

majority of the mothers (61.6%) perceive that breast

feeding is important and prevents childhood diseases,

while some others (38.4%) ignore that. However,

97.1% of the mothers commence breastfeeding 3 days

after delivery. The average period of breast feeding is

eleven months. Mothers who did not breast feed their

children; have attributed that to death of a mother

(25%), infection of mother with tuberculosis or

psychiatric diseases (50%), or the child being sick

(25%).

During the early 6 months of a new born baby,

89.9% of the mothers used to breast feed their

children and give supplementary food, while few

mothers (7.2%) exclusively breastfeed, and still very

few mothers (2.9%) wholly depend on supplementary

food. During the second half of the first year of a child

(6 - 12 months), very few mothers (0.41%) depend on

breast feeding as the main source of feeding their

children, while 87.7% of them combine breast feeding

with supplementary food, and 10.9% give their

children supplementary food only. This means that,

the majority of mothers did not change their

behavioral pattern of feeding their children throughout

the first year of a child life. However, children prefer

biscuits (14.3%), soft drinks (25.4%), and chips

(12.3%), juice (9.4%), cakes (5.8%), and sweets

(8.6%) as supplementary food types. This indicates to

shift from traditional food types to ready - made food

among urban households. The majority of children

(63.8%) take three meals a day, 21.9% take four meals

a day, 2.9% take more than four meals a day, and

11.6% take two meals a day. The majorities of the

households share the same dish (84.8%), or eats

separately (15.2%).

Table 6 depicts average daily intake of energy,

protein, iron, and vitamin A among children suffering

anemia and night blindness. From the table, children

aged less than one year old ranked first in energy

intake compared to other two groups of 1-3, and 4-6

year old. Taking two age groups of children together,

children aged <1 year old + 4 - 6 years old ranked first

and followed by those aged <1 + 1- 3 years, with very

small difference between them.

Drugs taken

during

Pregnancy/

Responses.

Vitamin A Iron others

preventive Curative Curative Folic Acid Fevol

Frequency % frequency % frequency % frequency % frequency %

Yes 16 11.6 4 2.9 47 34.1 2 2.9 29 21

No 118 85.5 118 85.5 91 65.9 134 97.1 109 79.0

total 134 97.1 122 88.4 138 100 138 100 138 100


195

Taking daily protein intake by age group of these

sick children, children aged less than 1 year old

ranked first, followed by 4-6 year old, and lastly 1- 3

year old. Taking two age groups together, had ranked

children aged <1 year old + 4-6 years old first, and

those aged 1 + 1- 3 years old second, while children

aged 1-3 + 4-6 came lastly. The general average

intake of protein for the three age groups reveals low

protein intake among children aged less than five

years old in Khartoum State. Moreover, ranking daily

intake of iron by age groups of these sick children

puts children aged <1 year old first, 4-6 year second,

and 1-3 year old last. There is slight difference in

daily iron intake when two age groups of children are

taken together. This is more particular to children in

the age groups of <1 + 1- 3 and 1-3 + 4-6 years old.

Table 6: Average daily intake of energy, protein, iron, vitamin A by age among children suffering anemia and night blindness

Table 7 depicts average hemoglobin measurement

by age groups of children by daily intake of animal

and plant protein. Highest percent of hemoglobin

among children aged less than one year old is

coincided with highest levels of animal and plant

protein intake. This is similarly seen among children

aged 4-6 year old. Taking two age groups together had

ranked children aged -1 + 4 - 6 year old first, and

followed by children aged -1 + 1-3 year old children,

with very small difference between them. Increasing

hemoglobin is associated with increasing protein,

confirming for better nutritional status of these

children. However, the general average of

hemoglobin, as well as the general average of both

types of protein is far below the recommended levels

for children to remain healthy. The fact here is that, an

increase in consumption of legumes will reduce Iron

absorption due to Fianite and Vitamin C which

reduces blood hemoglobin.

Table 7: Average hemoglobin measurement (%) and daily intake of animal and plant protein among children suffering anemia

and night blindness by age groups

3.6. Factors influencing children suffering anemia

and night blindness

Table 8 depicts highly significant probability

confirming the relationship between household

monthly income and number of meals a child takes

per day. This implies increased food expenditure and

higher level of energy; protein; iron; and vitamin

intake, as well as consumption of better quality

protein, with increasing income. Less income will of

course result in prevalence of anemia and night

blindness in the study area. However, the relationship

between nutritional status of children suffering anemia

and night blindness and type of food of a mother

Age groups No. Energy (calorie) Protein (g) Iron (milligram) Vitamin A (microgram)

<1 50 1127777 32675 5376 123977

1-3 153 854273 24877 4070 85870

4-6 106 975676 27974 4577 97977

<1 + 1- 3 66 547670 15575 2577 53474

<1 + 4-6 74 548473 15977 2675 63879

1-3 + 4-6 176 490076 14070 2277 46278

<1 + 1-3 +4-6 76 371574 10677 1775 36674

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196

during pregnancy gave highly significant probability

(Table 8). The food types during pregnancy (table 4)

reflect household monthly income level, educational

attainment, and other socioeconomic characteristics of

the surveyed households in the study area.

Table 8: Chi-Square test for relationships between some socioeconomic factors and nutritional status of children suffering

anemia and night blindness in Khartoum State

The relationship between sex and age structure of

children suffering anemia and night blindness and

frequency of daily intake of bread and cereals (P =

0.0008), milk and milk products (P= 0.0008); legumes

(P = 0.0007); vegetables (P = 0.0001); fruits (P =

0.0005); and other food types (p = 0.0004); are

positive and highly statistically significant which

suggests for influence of food nutrients on anemia and

night blindness during early childhood. There is

highly significant relationship between nutritional

status of children suffering anemia and night

blindness and number of children under five year old

in the household (P= 0.0002). This points out to

decreasing food nutrients intake with increasing

number of persons sharing the common dish which its

protein content was originally low. This is further

depicted by the relationship between nutritional status

of these sick children and ideal method for food

distribution in the family (P = 0.027). Since energy

and protein intakes (Table 6) were less and the

households are big enough, it is expected to have

positive relationship between household size and

nutrition status of these sick children. In addition,

relationship between hemoglobin level (%) and

amounts of animal protein consumed is positively

statistically significant (P= 0.01); and similarly with

plant protein (P= 0.03).

However, other factors influencing nutrition status

of children less than 5 years old in the study area

might include those operating at the national level.

They are financial inflation and corruption; absence of

social development, insufficient productive capital


197

investment in agriculture and industry, lacking

development policies that care or rural – urban

development and armed conflicts.

4. DISCUSSION

The investigation of nutritional status of children

suffering anemia and night blindness in Khartoum

State suggests low hemoglobin rate; inadequate food

intake and prevalence of malnutrition by age and sex

with major and minor differences. Males suffering

anemia and night blindness are more malnourished

compared to females. This agrees with the fact that,

generally children suffer night blindness between

second and fifth year of childhood, with more

emphasis to males than females, but differs

concerning anemia which prevails more between 6 to

8 months of a childhood, but with more emphasis to

males than females (Hassan et al., 2002). The high

rate of hemoglobin concentration among children

aged less than 1 year old might be attributed to more

care given to a lactating mother in Sudanese culture

which effectively supports neonatal period and early

childhood, where relatives could supply with

nutritional food types such as sweet porridge.

Children aged 1-3 year old have less hemoglobin

concentration and suffers Iron deficiency anemia

compared to the two other two groups. This might be

attributed to average short period of parities and to

poverty which make the majority of Sudanese to

afford living costs in situations of accelerating

financial inflation. However, prevalence of breast

feeding in the study area is attributed to the awareness

of mothers to its nutritional value to a newborn child,

and to the inherited Islamic culture which enhances

mothers to breast feed their children for two complete

years. It might be also attributed to the fact the

majority of urban households are incapable to

purchase readymade food for their children where 70

to 80% of urban population live below the poverty

line (Hamid, 2000), and also many of the mothers are

mainly housewives who have devoted themselves to

child bearing. However, this is supported by the fact

that, during pregnancy and lactation, mothers used to

consume vegetables, fruits, milk, cereals, meat, and

legumes abundantly compared to less amounts of

these food types during lactation.

Prevalence of low weight and malnutrition among

children less than 5 years old in Khartoum State

(Table 2) is almost similar to the 50 % cited by FAO

and WFP for pre-2001 studies for North Kordofan

state (FAO/WFP, 2006). However, it was higher than

the most recent report Sudan household health survey

of 42.9% (SHHA, 2006). The result was also higher

than all previous studies carried out in Sudan,

although it is similar to that by Al Jaloudi for children

less than five years old living in poor urban Khartoum

state (Al Jaloudi, 2000). In addition, the difference in

malnutrition is possibly due to geographic reasons. In

Khartoum State, squatter areas have expanded rapidly

in recent decades, occupied by poorest people who are

generally facing inadequate food intake and

unhygienic residential environment (Alredaisy and

Davies, 2003, Babiker and Alredaisy, 1997).

However, since the majority of mothers did not take

preventive or curative doses of Vitamin A during

pregnancy (Table 5), this makes mothers and new

born infants vulnerable to many childhood diseases.

However, this situation might be milder when putting

into consideration that 61% of the mothers have been

vaccinated, 32% partially vaccinated, and only 7%

were not vaccinated. The general average intake of

energy for the three age groups reveals low energy

(calories) intake among children aged less than five

year old in Khartoum State. The general average of

daily iron intake depicts very low level among these

children. This picture is also seen when daily intake of

Vitamin A is taken into consideration.

Average daily intake of energy, protein, iron, and

vitamin A by age groups of children suffering anemia

and night blindness had identified children aged less

than one year as the most advantageous group

compared to the other two groups. In addition, the

general average of each of these nutrients is far below

the recommended level for children to remain healthy

in Arica and Sudan. Comparing macronutrients daily

intake in the study area (Table 6) with the study by

Ministry of Agriculture and Forestry of Sudan (FSU,

2005) puts the study area below by that there are less

protein, carbohydrates and lower energy intakes.

There is less animal protein; vitamins, minerals

consumed and abundant cereal are consumed. In the

study area, fat and carbohydrates (calories) consumed

were lower than the recommended values (Katch,

1983) and for population in Africa which is 2041.7

calories (Latham, 1997). This study agrees with

Mohammed's study in Al Shigla area in east

Khartoum State, which indicated to imbalanced intake

of food types where legumes and cereals are

abundantly consumed while meat, fish and chickens

are less consumed among surveyed households

(Mohamed, 1999). It also agrees with Ali's study in

north state of Sudan where cereals are the main source

for poor households although cereals are deficient in

vitamin A, and 41% of the sample suffers vitamin A

deficiency (Ali, 2005). Energy obtained by higher

protein and carbohydrates intakes was more than

double the value obtained by excess fat intake in this

study (FSU, 2005). Cereals highly contribute to

energy and protein intake in the study area, a situation

similar to rural Philippines where 361g/person/day are

consumed there (Florentino, 1996). Animal protein

Alredaisy and Saeed



198

sources such as meat and milk provide less than the

recommended value which is 55.3g (FSU, 2005).

The high fertility rate of population of the study

area agrees with general demographic trends in Sudan

where total fertility rate was 5.9 births per woman in

1999; annual population growth rate was 2.53 %

between 2003 and 2007 and the natural rate of

increase was 41.23 per 1 000 in 2006 (Ministry of

Health, Sudan. 2008). Dominance of Low income

groups in the study area agrees with figures in Sub–

Saharan Africa where about half the population is

living below the poverty line, with both numbers and

percentage on the increase (Alredaisy, et al., 2001).

Generally, growth of towns and cities in Sudan has

been accompanied by growing numbers of poor and

vulnerable urban dwellers (Sara Pavanello, 2011).

Although Sudan is rich in natural and human

resources, 77.5% of the households surveyed in north

Sudan were on or below the poverty line (MOL and

ILO, 1997]. The study by the United Nations

Development Program in 2005 reported that 75% of

north Sudan population as poor and the majority

(80%) is concentrating in rural areas where 30% of

them suffered from extreme poverty (United Nations

Development Program, 2005). The majority of the

urban poor are dependent upon marginal livelihood

activities in the informal economy, and their access to

safe and sustainable livelihoods is extremely unstable

(Sara Pavanello, 2011). However, factors influencing

income attainment in the study area might include

those operating at the national level including absence

of social development and insufficient productive

capital investment (UNDP, 1998), ill-conceived

development policies and armed conflicts (Zeng,

2003).

Fieldwork results depicted positive relationship

between number of meals a child takes per day and

household monthly income (table 8). Some

researchers are convinced that increasing income

leads to increasing food intake (Strauss 1984,

Maxwell et al 2000) while some others believe that

poor households spend their additional incomes on

more expensive foods such as finer cereals, meat or

dairy products which do not necessarily yield more

energy. The fieldwork results support the first

assumption that increasing income had positively

increased number of meals a child takes per day and

therefore more energy and protein intakes are

expected. Less income resulted in prevalence of

malnutrition in the study area, thus decreasing income

might lead to marginal or sub-optimal intakes of

energy and protein resulting in more prevalence of

anemia and night blindness. In addition, it is expected

that more energy and protein will positively correlate

with three meals per day other than with two meals.

Higher level of protein intake implies consumption of

better quality protein with increasing income. There is

significant increase in energy and protein intakes with

increasing incomes and a similar increase that was

highly significant were recorded for protein (Ibrahim,

2008). Many studies in Sudan referred low weight

among young children to unequal income distribution,

vertically between incomes and horizontally between

rural and urban areas (UNDP 2006). Furthermore,

increased income will increase food expenditure in the

study area as has been confirmed in rural western

Kordofan State (Alredaisy and Suleiman, 2011) that

had significantly increased energy and protein intakes

in the study area for both energy, probability of 0.042,

and for protein with probability of 0.025, and

significant relationship exists between food

expenditure and undernutrition prevalence in the study

area with probability of 0.004.

The relationship between nutritional status of

children and type of food consumed during pregnancy

is highly significant (0.0056). This might be attributed

to household monthly income, educational level of a

mother or a father where the majority has attained

religious or basic education. Mothers' literacy

positively effects low weight- for- age compared to

illiterate mothers who have more stunted children in

Sudan (FAO/WFP, 2006), and in Khartoum State

(Magboul et al, 2000) and SERISS (1988) and SMCH

(1995) results where mothers' educational level was

remarkably influential.

One of the main reasons for generally declining

levels of food consumption in the study area is

attributed mainly to the high living costs and high

inflation rates in Sudan. The high expenditure on food

in situations of low income, big households and

illiteracy has many consequences. One consequence is

that, a low-income household's consumer surplus for

food is very high, amounting to a substantial

proportion of its total income. This has important

consequences for the economic appraisal of food

supply. With regard to affordability, households are

unable to pay for food at the current cost. High

proportion would be unable to pay the actual costs of

food. The revenue that may realistically be expected

to be recovered from these households in the future

lies somewhere between what they are able to pay and

what they are presently willing to pay. Another

consequence is the lack of elasticity and repercussions

on expenditure for food would imperatively be

retarded. The high price of food in urban Sudan is

probably a major cause of the malnutrition prevalent

in the squatter areas (Sandy et al, 1992). Decreasing

income led to marginal or sub-optimal intakes of

energy and protein resulting in more prevalence of

under-nutrition in rural western Kordofan of Sudan

(Alredaisy and Suleiman, 2010). Many studies in

Sudan referred low weight, stunting and wasting

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199

among young children to unequal income distribution,

vertically between incomes and horizontally between

rural and urban areas (UNDP, 2006).

5. CONCLUSION AND RECOMMENDATIONS

The general conclusions of this study are as follows:

1- Children aged less than five year old living in

Khartoum State are suffering anemia and night

blindness.

2- Malnutrition and underweight are prevalent in

Khartoum State.

3- Promotion of community and child nutrition is a

necessity in the study area.

4- Many interrelated socioeconomic factors are

influencing anemia and night blindness.

5- Promotion of child nutrition and urban living

conditions is a necessity in the study to combat these

two diseases.

Based on that, some suggestions could be

presented. Firstly, breast feeding should be enhanced

from delivery up to six months of a child’s age, and

should be accompanied by supplementary feeding

thereafter up to the completion of two years of a child

age. Secondly, more care should be devoted to

qualitative and quantitative complementary feeding.

Thirdly, introduction of balance diets rich in vitamin

A, and Iron when a child completes six months of age,

and during pregnancy and lactation is a necessity.

Fourthly, nutrition education should be introduced and

enhanced among mothers to accept knowledge about

good child feeding. Fifthly, urban poor should be

supported by appropriate socioeconomic development

programs to curb financial inflation which adversely

depriving this segment of the society. Promotion of

urban living conditions could be through provisioning

adequate housing conditions; income generation

sources to poor urban households; stopping

accelerated financial inflation; and reducing rates of

rural - urban migration to avoid addition of more

urban poor and growth of squatter settlements. In

addition, Sudan has to work hardly to solve political

problems with South Sudan Republic and the

rebelling militia in Darfur, southern Kordofan, and

Blue Nile to achieve stability that will reflect on

development of agriculture and industry that will

certainly promote nutrition status of the young

growing generations of Sudanese youth.

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201

Samir Mohamd Ali Hassan Alredaisy is Associate Professor at University of Khartoum. He received his

first degree from University of Khartoum in 1983/ He obtained Masters from University of Khartoum,

and PhD from University of Wales, Swansea in 1993. His current research focuses on Medical

Geography of Sudan. To date, he published more than 40 referred papers, and 20 textbook and

reference.

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obtained her first degree in nutrition from Ahad University and her Masters in Science from University

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problems in Gezira area, particularly among prgnat mothers and newborn children.


ISSN: 2322-4541; ©2013 IJSRPUB


202


Remediation of Tetrachloroethylene -Contaminated Soil with Zero Valent Iron

Utilizing Electrokinetic Reactors

Maryam Taghizadeh1, Daryoush Yousefi Kebria

2,*

1Department of Civil and Environmental Engineering, Babol Noshirvani University of Technology, Iran

2Assistant Professor in Civil Engineering, Babol University of Technology, P.O. Box: 484, Babol, Iran.

*Corresponding Author: [email protected]

Received 21 April 2013; Accepted 25 May 2013

Abstract. This study was conducted to evaluate an integrated technique a combination of electrokinetics (EK) and zero-valent

iron and a nonionic surfactant, Triton X-100(TX-100), which was selected as the solubility-enhancing agent for the

remediation of soils-contaminated with Tetrachloroethylene (TCE). Four Lab-scale tests (T1 toT4) were conducted to

investigate the performance of EK-PRB on TCE removal from soils. Electrical current, cumulative electro-osmosis flow and

the pH in anode and cathode reservoir were measured every 24h during the run. Results show that coupling EK with ZVI- PRB

would greatly enhance the removal efficiency of TCE from soils. With this method TCE removal would generally be increased

by approximately 40% when EK is coupled with PRB as compared with EK alone. The highest TCE removals were

respectively recorded in T4 about 80% and 55% near to the anode and cathode of the electrokinetic cell.

Key words: Combination of Electrokinetics and zero-valent iron, Tetrachloroethylene, Surfactant, Triton X-100, soil, Electro

osmosis

1. INTRODUCTION

Chlorinated organic compounds (COCs) refer to the

substitution of one or more hydrogen in aliphatic and

aromatic hydrocarbons and their derivatives by

chlorine. COCs are widely used in the fields of

chemistry, medicine, electronics, pesticides, ect. Many

COCs are endocrine disturbance substances; show

carcinogenic effects, and have been listed as priority

pollutants by the US Environmental Protection

Agency (USEPA). When released into the

environment, COCs are transported in both air and

water. However, COCs are chemically stable and

difficult to destroy, and they are eventually deposited

in soils and sediments due to their hydrophobic it. Soil

and sediments contaminated with COCs are long-term

sources of pollutants and pose great threats to human

health and ecosystems. Therefore, remediation of

these contaminated soils and sediments is of great

importance (Reddy and Camesella, 2009).

Various chlorinated organic compounds, including

tetrachloroethylene (TCE), are widely used as

solvents in various industries. When entering the

subsurface environment, they generally would pose

great threats to the environment as well as human

health. For example, TCE is harmful to the central

nervous system of human bodies and can enter the

body through respiratory or dermal exposure.

Tetrachloroethylene dissolves fats from the skin,

potentially resulting in skin irritation. Because of

these hazards to the environment and potential

groundwater contamination, remediation of TCE

contaminated soils is necessary to reduce public

health risk (WHO, 2006).

Few remediation technologies are available for the

removal of chlorinated hydrocarbon from rather low

hydraulic permeability media, such as clay. The use of

an electrokinetic (EK) process in soil remediation has

received increasing attention worldwide because of its

unique applicability to low-permeability soils

(Khodadadi et al., 2011; Gholami and Yousefi Kebria,

2012).

Electrokinetics, also known as electroreclamation,

electrokinetic soil processing, electrokinetic

extraction, electrodialytic remediation and

electrochemical decontamination is the application of

a DC current to induce the movement of chemical

species. Electrokinetic phenomena comprise of (i)

electromigration- the movement of charged ions due

to an electric potential difference, (ii) electrophoresis-

the movement of colloids or macromolecules due to

an electric potential difference and (iii)

electroosmosis- the bulk movement of water due to an

electric potential difference. Electrokinetics is not

affected by the hydraulic conductivity of the soil

matrix, and thus has the potential to be a treatment

technique for soils possessing low hydraulic

conductivities (Van Cauwenberghe, 1997).

EK has been reported to be successful and a cost-

effective method to treat both organic (Yalcin et al.

1992, Weng et al., 2003) and inorganic contaminants

(Coletta et al., 1997; Alshawabkeh et al., 1999; Sah

Taghizadeh and Kebria


203

and Lin., 2000) from low permeability soils (Weng et

al., 2007).

To improve the efficiency of EK remediation for

TCE-contaminated soils, the combination of EK with

other techniques may provide a solution. For example,

the effect of electrokinetic on the microbial

remediation of PCP contaminated soil was

investigated. However, the introduction of

microorganisms into soil with low permeability is still

a problem in the bioelectrokinetic process.

Comparatively, electrokinetics coupled with a

permeable reactive barrier (PRB) can simultaneously

realize the EK transport and PRB destruction of

contaminants. Great enhancement has been recorded

for the treatment of contaminants in soils by EK-PRB

(Li et al., 2011).

In the present study, a PRB filled with Fe particles

was installed between anodes and cathodes in order to

reach an enhanced remediation of TCE-contaminated

soil. When TCE transports through the PRB, it can be

dechlorinated to ethylene, which has much lower

toxicity and larger aqueous solubility than TCE. The

electroosmotic removal of ethylene can therefore be

achieved easily.

Because TCE is weakly water-soluble and has

preferential sorption in soils, it is very difficult to

drive out via electro-osmosis. As a result, surfactants

are the facilitating agents that both lower the

interfacial surface tension and increase the solubility

of TCE through a process called micellar stabilization

Surfactant-enhanced electro-osmosis remediation

techniques and surfactants can be adsorbed at

interfaces and reduce interfacial energies. Therefore,

surfactants can be used to mediate mass transport in

the dechlorination process. Surfactant enhanced

remediation has been suggested as a promising

technology for the remediation of contaminated soils

and groundwater (Zheng et al., 2009).

The objectives of this study are (1) to assess the

remediation efficiency of PCE contaminated soil by

electrokinetics coupled with Pd/Fe PRB, (2) to

evaluate the migration and removal of PCE and its

dechlorination products during remediation process.

Triton X-100 (TX-100) was chosen as the

enhancement agent because of its solubility-enhancing

capacity for TCE.


2.1. Chemicals and materials TCE and microscaled zero-valent iron was purchased

from DAE JUNG, Korea. Triton X-100 (TX-100) was

from Merck and was used as received.

The model soil in this study was collected from the

top soil layer (50 cm in depth) from farmland located

in northern Iran. The physical-chemical properties of

soil are listed in Table 1. The texture of this soil was

classified as clay.

Table 1: Soil properties

Characteristics value

Texture clay

Organic Content (%) 7.7

Soil pH 7.6

Density (g/cm3) 2.71

Optimum Moisture (%) 25

Porosity (%) 40.3

Permeability (cm/s) 6×10-3

The soil samples were air-dried and passed through

a 2mm sieve, then for preparation of simulated TCE-

contaminated soil at a concentration of 600 mg.kg-1

dry soil, was made by adding 600 mg TCE and 100

mL acetone to 1000 g dry soil, and then this was

thoroughly stirred to obtain simulated TCE-

contaminated soil. The simulated soil was then dried

in air for 24h and stored in the dark bottle for

treatment. The uniform distribution of TCE in

simulated TCE-contaminated soil was verified by the

consistency of gas chromatography (GC) analysis for

three random samples.

2.2. EK-PRB experiment

Lab-scale EK-PRB experiments were conducted in a

setup as shown in Fig.1. The setup was comprised of

two Plexiglas soil columns (4.5*4.5*6cm), one PRB

compartment (1*4.5*6cm) and two pairs of electrolyte

compartments (4.5*5*6cm) which were used as the

EK cell. Perforated graphite electrodes (50*40*5mm)

were used as anodes and cathodes. The anode flushing

solution was siphoned from a stocking bottle via a soft

rubber tube, which was attached to a piston in order to

control the inlet flow. The electro-osmotic flow in the

cathode was collected and measured with a 500mL

cylinder whose top was sealed with gummed tape to

avoid the evaporation of water. The constant potential

was supplied by a DC power (DAZHENG, 30V/5A).

The electric current was monitored with a multimeter.

Electrical current and cumulative EOF was measured

every day during the run. Contaminated soil was prepared by mixing a TCE

solution and soil with a water content of 25% in order

to reach 600 mg TCE per kilogram of dry soil. About

400 g of contaminated soil were used. This was

compacted in five additions under a static load of 50

kPa; leading to specimen dimensions of 4.5*4.5*6 cm.

Filter paper was sequentially attached to each end of

the column to avoid the leakage of soil particles.


204

Fig. 1: Schematic diagram of EK-PRB setup

The acid-washed iron particles were then blended

with acid-washed quartz sand (with the initial mass to

mass of 1:1) to ensure even dispersion and impede

clogging by iron precipitation. The columns were

weighted and assembled with the electrodes and

compartments; meanwhile approximately 30 g of PRB

materials was loaded into the PRB compartment.

Four tests were carried out with parameters as

listed in Table 2. In T3-T4 the surfactant was used in

order to increase efficiency. In T3, surfactant was

used as an anode-flushing solution and in T4,

surfactant is mixed with soil. The electric field

induced significant pH changes at both cathode and

anode. Furthermore, in order to prevent, or control,

the resulting changes in soil chemistry, the pH of

either electrolyte could be controlled with manual

addition of either sulphuric acid (at the cathode) or

sodium hydroxide solution (at the anode). As shown

in Table 2, the control experiment of T1 was

conducted to depict the transport behavior of PCE

under electric field without PRB. From T2 to T4, PRB

was installed at the position of 0.5 (normalized

distance from anode).

Table 2: Associated parameters with EK-PRB tests

No. PRB Anode

Column

Cathode

Column

Duration(day)

T1 No Spiked Soil Spiked Soil 10

T2 Yes Spiked Soil Spiked Soil 10

T3 Yes Spiked Soil Clear Soil 10

T4 Yes Spiked Soil Spiked Soil 10

2.3. Analysis of the samples

At the end of the EK experiments, soil was extracted

from the electrokinetic cell and divided into three

sections along the length of the cell to analyze the

spatial distribution of the pH and residual TCE

remaining in the soil. pH was measured with a pH

meter (HANNA, HI-8314, Italy) by mixing 3 g soil

sample with 7.5 ml NaCl 0.02 M. For the analysis of

TCE in moist soils, samples were dried in air for

about 48h. Each sample was prepared twice. Then, the

samples passed through a 2mm sieve. In order to

extract the target organics from the soil, 2 g dry soil

was mixed with 2 mL 0.1 M sulfuric acid and 5 mL

hexan for shaking 24 h. The chlorinated organic in the

extractor were determined by gas chromatography

equipped with an electron capture detector (GC/ECD,

Varian CP3800). After analyzing experimental data,

the removal efficiency of TCE under different

experimental conditions could be obtained. The

recovery of TCE in the processes was verified to be

above 85%.


3.1. Variation of electrical current during EK-PRB

experiments

In all experiments, a constant voltage was applied

across the electrodes. It was found that, whilst the

voltage between the electrodes was kept constant, the

potential difference across the soil was variable and

impossible to control in this manner. This effect was

due to the movement of ions and changes in moisture

in the soil system (Li et al., 2011).

Fig. (2) Displays the variations of electrical current

versus time for the four tests. As shown in Fig. (2), the

current decreased in 10 days. In general, the maximal

current was reached at the start of test when the

quantity of ions in the pore solution was the greatest.



205

Fig. 2: Variation of electrical current in EK tests

Fig. 3: Variation of cumulative EOF in EK tests

The increase in current indicates that many ions

entered into the soil column, while the decrease

suggests the moving out or precipitation of ions (Li et

al., 2011). Comparison of the electrical current during

2-10 days in four experiments indicates that tests with

PRB had higher currents than tests without (T1),

suggesting a slight promotion on the electrical current

with the presence of PRB. The variation of current is

in agreement with that which was reported by Chang

and Cheng (Chang and Cheng., 2006), whereas the

EK-ZVM test had a higher electrical current than the

EK test, due to the higher conductivity of pore

solution and lower resistance of high electric

conductive ZVM (Chang and Cheng., 2006; Wan et

al., 2010).

3.2. Variation of cumulative EOF during EK-PRB

Flow induced by the presence of an electrified field

was found to have a certain amount of repeatability

between experiments, in that the flow would initially

be slow to start, and then accelerate substantially,

before reducing or stopping entirely. The results of

four different experiments are shown in Fig. (3).

Fig. (3) Reveals that the cumulative EOF collected

at the cathode reservoir varied from test to test.

According to the Helmholtz-Smoluchowski equation,

the EO velocity is directly proportional to the zeta

potential of soil and the dielectric constant of pore

fluid (Virkutyte et al., 2002; Richard and Krishna,

2005).


206

As known, considerable H2 can be generated by

the ZVI system, due to the decomposition of H2O by

Fe (0) (Zhang, 2003; Wan et al., 2010).

So there would be an accumulation of gas in the

PRB compartment, which would dramatically

decrease the dielectric constant of the pore fluid

within the system. Furthermore, the presence of quartz

sand could further contribute to the decrease of

dielectric constant of pore fluid, considering its poor

conductivity when compared with water or even soil.

The lower permeability of soil in cathode regions,

which was caused by the block of Fe oxides, formed

because of the very alkali circumstance near the

cathode. This was indicated by an increasing dark-

green color in the cathode regions during the EK-PRB

process. In addition, higher ion strength of the pore

solution due to the dissolution of ZVI is also expected

to impede the EOF by compressing the thickness of

diffusive double layer (Wan et al., 2010).

According to Fig. (3) With the addition of TX-100

(T3 and T4), the cumulative EOF of T3-T4 in ten

days, was more than that of T1 and T2. The

absorption of TX-100 within soil will reduce the

absorption of mobile ions, release the ions and reduce

the formation of precipitate (Yuan et al., 2006).

Besides, as a kind of dispersing agent, TX-100 could

improve the permeability of soil (Siachek and Reddy,

2002). Thus, the pore Fluid could be mobilized more

smoothly in T3 and T4 than in T1 and T2.

3.3. pH distribution

Changes in the pH of the electrolyte fluids were found

in all experiments, due to water electrolysis at the

electrodes. It was expected that the hydrogen and

hydroxyl ions produced would migrate into the soil,

primarily through electromigration and diffusion,

changing the pH of the soil pore fluid. This was

observed many times (Virkutyte et al., 2002; Wan et

al., 2009). Typical results from a range of different

experiment types are presented in Fig. (4). According to Fig. (4), in ten days, pH in anode

reservoirs decreases due to the production of H+, and

increase in cathode reservoirs due to production of

OH-.

In comparison, tests without PRB showed a higher

pH, which may be attributed to less H+ generation at

anodes due to the lower electrical current.

Furthermore, it can be found that tests with PRB

exhibited a more fluctuant pH compared with tests

without PRB. It is suggested that in the presence of

PRB, reactions between Fe particles and the

contaminants, the corrosion and transformation of Fe

and its oxides, as well as reactions associated with

quartz sand may all affect the variation of pH (Wan et

al., 2009).

3.4. Soil pH distribution

The soil pH values across the columns, upon the

completion of EK tests, are plotted in Fig. (5) Due to

water electrolysis at the electrodes the soil pH near the

anodes drop and the soil pH near the cathodes rise.



207

Fig. 4: Variation of (a) anolyte and (b) catholyte pH

Fig. 5: Distribution of soil pH

According to the Fig. 5, pH in the soil sample did

not indicate many changes due to buffering properties

of soil compared to the initial soil pH (7.6). Overall,

pH increases from the anode to the cathode and it did

not change more than 2 units. These negligible

changes indicate that the pH control is partially at the

right time at the anode and cathode reservoir.

3.5. Distribution of TCE in the soils

TCE is highly insoluble in water and is preferentially

absorbed in soils. It is therefore difficult to drive TCE

out by electro-osmosis. In order to accomplish the EK

remediation of TCE contaminated soils, the first step

is to de-absorb TCE from soils and dissolve it in a

porous solution. Surfactants have both hydrophilic

and lipophilic groups, so it can improve the solubility

of many HOCs (Ko et al., 2000; Reddy and Richard,

2003; Saichek and Reddy, 2002). Fig. (6) Illustrates

removal percentage in the four tests upon the

completion of remediation.


208

Fig. 6: Removal percentage of TCE in EK tests

Table 3: Mass balance of TCE for four tests

Test No Initial Mass(mg) Soil Column (mg) Catholyte (mg)

Anode Middle Cathode

T1 240 59.77 69.77 73.07 25.95

T2 240 91.08 16.34 98.8 31.6

T3 240 67.08 31.18 11.01 60.11

T4 240 23.54 28.82 50.1 60.7

In addition, the mass of TCE in each column and

in cumulative EOF was calculated and listed in Table.

3.

The curve of T1 in Fig. 6 depicts the movement of

TCE in the electric field without the influence of PRB.

TCEs near the anode were moved to the middle

section and the cathode via electro-osmosis. As shown

by the mass balance calculated in Table. 3, negligible

TCE was removed from the soil in T1, which is

indicative of low EK remediation efficiency for TCE-

contaminated soil. The observation confirms the fact

that EK alone can only facilitate a reliable removal of

HOCs in anode regions, as found was confirmed

several previous studies.

When PRB was installed, as indicated in T2, more

TCE near the anode column migrated towards the

cathode when compared to T1. Correspondingly, the

overall TCE removal in the cathode column in T2 was

much higher than that in T1. For T3 and T4, TCE

distribution in the anode column was higher than T2,

and in the cathode column, the residue was lower than

in T2. Particularly, no detectable TCE was recorded in

the cathode regions in T3, suggesting that no TCE

from the anode column moved into these regions.

In the EK-PRB process, there are two main

approaches that contribute to the removal of TCE

from soils. One is the electro-osmotic (EO) movement

of contaminants across the soil from anode to cathode,

which plays a primary role in HOC removal in

conventional EK remediation (Siachek and Reddy,

2002; Virkutyte et al., 2002).

The other is the adsorption/degradation of TCE by

Fe particles in the PRB compartment. Generally, EO

functioned as the predominant approach to move TCE

in the anode column, and ZVI-PRB functioned as a

unit to remove TCE that was moved by EOF from the

anode (Li et al., 2009).

Comparison of TCE residue in an anode column

(Table. 3) reveals that the test with PRB generally

obtained an overall TCE removal of about 70%,

which was nearly 40% higher than by EK alone. This

reliable promotion in contaminants removal with the

combination of EK and ZVI-PRB has also been

reported in literature (Mooon et al., 2005; Yuan et al.,

2006).



209

4. CONCLUSIONS

In this study we investigated the performance of EK-

PRB technique to remediate TCE in contaminated

soils. TX-100 was selected as a solubility-enhanced

agent and microscale Fe particles were used as a PRB

material. The results showed that EK-PRB could

greatly enhance the removal of target contaminants in

soils. Major conclusions can summed up as follows:

1) The integration technique is feasible to clean up

TCE contaminated soils in a lab scale; the best TCE

removal efficiency can reach 79% after a 10-days

treatment.

2) The combination of EK and Fe (0) PRB could

increase the overall TCE removal from soils by 40%

when compared with EK alone. The results also

suggest that TX-100 is a superior enhancement agent

for TCE removal, both in the EOF movement process

and in the Fe (0) degradation process.

3) Mass balance of TCE revealed that in the EK-

PRB system, TCE could be removed from soil

through several sequential processes: the movement

driven by EOF in the anode column, the complete

adsorption/ degradation by the Fe (0) PRB and the

consequent movement by EOF and probable

degradation by electrochemical reactions in the

cathode column.

4) Comparison of the electrical current during 2-10

day in four experiments indicates that tests with PRB

due to the higher conductivity of pore solution and

lower resistance of high electric conductive ZVM had

higher currents than tests without (T1).

REFERENCES

Alshawabkeh AN, Yeung AT, Bricka MR (1999).

Practical aspects of in-situ electrokinetic

extraction. Journal of Environmental

Engineering, 125(1): 27-35.

Chang JH, Cheng SF (2006). The remediation

performance of a specific electrokinetics

integrated with zero-valent metals for

perchloroethylene contaminated soils. Journal

of hazardous materials, 131(1): 153-162.

Coletta TF, Bruell CF, Rayan DK (1997). Cation-

enhance removal of lead from kaolinite by

electrokinetics. Environmental Engineering

Science, 123(12): 1227-1233.

Gholami M, Yousefi Kebria D (2012). The

comparison of phytoremediation and

electrokinetic methods in remediation of

petroleum hydrocarbons contaminated soil.

Second International Conference on

Geotechnique, Construction Matrials and

Environment, Kuala lumpur, Malaysia Nov. 14-

16, 2012(ISBN: 978-4-9905958-1-4 C3051).

Khodadadi A, Yousefi D, Ganjidoust H, Yari M

(2011). Bioremediation of diesel- contaminated

soil using Bacillus sp. (stratin TMY-2) in soil

by uniform and non- uniform electrokinetic

technology field. Journal of Toxicology and

Environmental Heaith Sciences, 3(15): 376-

384.

Ko SO, Schlautman M. A.., E.R. Carraway (2000).

"Cyclodextrin-enhanced electrokinetic removal

of phenanthrene from a model caly soil."

Environ. Sci. Technol 34: 1535-1541.

Li Z, Yuan S, Wan J, Long H, Tong M (2011). A

combination of electrokinetics and Pd/Fe PRB

for the remediation of pentachlorophenol-

contaminated soil. Journal of contaminant

hydrology.

Li TP, Yuan SH, Wan JZ, Lin L, Long HY, Wu XF,

Lu XH (2009). Pilot-scale electrokinetic

movement of HCB and Zn in real contaminated

sediments enhanced with hydroxypropyl-beta-

cyclodextrin. Chemosphere, 76: 1226-1232.

Moon JW, Moon HS, Kim H, Roh Y (2005).

"Remediation of TCE-contaminated

groundwater using zero valent iron and direct

current: experimental results and electron

competition model. Environ. Geol., 48: 805-

817.

Reddy KR, Cameselle C (2009). Electrochemical

remediation technologies for polluted Soils,

sediments and groundwater. Wiley.

Reddy Krishna R, Saichek RE (2003). Effect of soil

type on electrokinetic removal of

phenantherene using surfactants and cosolvents.

J. Environ. Eng., 129: 336-346.

Sah JG, Lin LY (2000). Electrokinetic study on

copper contaminated soils. Journal of

Environmental Science & Health Part A, 35(7):

1117-1139.

Siachek Richard E, Reddy Krishna R (2002). Effect of

pH control at the anode for the electrokinetic

removal of phenanthrene from kaolin soil."

Chemosphere (51): 273-287.

Siachek Richard E, Reddy KR (2005).

Electrokinetically enhanced remediation of

hydrophobic organic compounds in soils: A

review. Critical reviews in environmental

science and technology, 35(2): 115-192.

Van Cauwenberghe (1997). Electrokinetics.

Groundwater Remediation Technologies

Analysis Center, To-97-03.

Virkutyte J, Sillanpää, M, Latostenmaa P (2002).

Electrokinetic soil remediation — critical

overview. Science of The Total Environment

289(1-3): 97-121.

Wan J, Li Z, Lu X,Yuan S (2010). Remediation of a

hexachlorobenzene-contaminated soil by


210

surfactant-enhanced electrokinetics coupled

with microscale Pd/Fe PRB." Journal of

hazardous materials 184(1-3): 184-190.

Wan JZ, Yuan SH, Chen J, Li TP, Lin L, Lu XH

(2009). Solubility-enhanced electrokinetic

movement of hexachlorobenzene in sediments:

a comparison of cosolvent and cyclodextrin. J

Hazard Mater., 166: 221-226.

Weng CH, Lin YT, Lin TY, Kao CM (2007).

"Enhancement of electrokinetic remediation of

hyper-Cr (VI) contaminated clay by zero-valent

iron." Journal of hazardous materials 149(2):

292-302.

Weng CH, Yuan C, Tu HH (2003). Removal of

trichloroethylene from clay soil by series-

electrokinetic process. Practice Periodical of

Hazardous, Toxic, and Radioactive Waste

Management, 7(1): 25-30.

WHO (2006). World Health Organization. Concise

International Chemical Assessment Document

68, Tetrachloroethylene.

Yalcin B, Li HRJ (1992). Phenol removal from

kaolinite by electrokinetics. J. Geotech. Eng.,

118(11): 1837-1853.

Yuan C (2006). The effect of Fe(0) on electrokinetic

remediation of clay contaminated with

perchloroethylene. Water Sci. Technol., 53: 91-

98.

Yuan S, Tian M, Lu X (2006). Electrokinetic

movement of hexachlorobenzene in clayed soils

enhanced by Tween 80 and B-cyclodextrin. J

Hazard Mater., B137: 1218-1225.

Zhang, W. X. (2003). "Nanoscale iron particles for

environmental remediation: an overview." J.

Nanopart . Res 5: 323-332.

Zheng Z, Yuan S, Yuan S, Liu Y, Lu, Wan X, Wu J,

Chen J (2009). Reductive dechlorination of

hexachlorobenzene by Cu/Fe bimetal in the

presence of nonionic surfactant. Journal of

hazardous materials, 170(2): 895-901.

211

Maryam Taghizadeh has MSC in civil engineering-Environment Science from Babol Noshirvani

university of Technology (Iran).Currently; she works in the Islamic azad university of behshahr. She

has more than 5 articles in the international conference and Journal.

Daryoush Yousefi Kebria has PHD in civil engineering-Environment Science from Tarbiat modares

University(Tehran-Iran).Currently, he is Assistant Professor in Civil Engineering, Babol University of

Technology. he has more than 7 articles in the international conference and Journal.


ISSN: 2322-4541; ©2013 IJSRPUB


212



Kodegandlu Venkatarayappa Narayanaswamy

Senior Member IEEE; Professor & Head of EEE, MSRUAS, Bangalore, India; Email: [email protected]


Abstract. Energy harvesting (EH) system is a new concept introduced for capturing or reusing energy from natural resources like

solar energy and wind energy. The EH system consists of two key components i.e. an EH unit and an energy storage device.

Monitoring and control of EH system is essential for its efficient and effective functioning, and reduces the cost required for

replacement of damaged storage devices caused due to overcharging. This research article propose an architecture for

monitoring voltage / state of the charge of EH system during charging and discharging process i.e. essential to protect the storage

device from overcharging / deep discharging using Wireless Sensor Network (WSN) technology. A prototype of voltage

monitoring slave sensor unit is designed to monitor overcharging / deep discharging of EH system. The monitored voltage is

communicated to the sink at periodic intervals. Master slave wireless communication is set up using Zigbee wireless module to

enhance communication between the monitoring slave sensor unit and master. The system is also scaled using remote

configuration capability to extend the monitoring of EH system by setting up threshold limit to protect the storage device from

over charging. By setting up the threshold limit an alert is generated by the monitoring unit and communicated to master over

Wireless Network (WN), the remote configuration also provides to put the monitoring unit in low power mode to extend the

monitoring unit life.

Key words: Energy harvesting, Wireless Sensor Network, Wireless Network, Cluster Heads

1. INTRODUCTION

The emerging technology has brought new

opportunities in EH system and WSN for data

monitoring and has given rise to expand WSN

potential prospects for monitoring and processing

various sensor information through wireless

communication. Improvements in EH system

technologies and utilization of renewable energy

source for power generation has attracted the young

researcher to expand the EH systems. EH system has

been in rapid development for renewable power

generation and monitoring EH system over WSN

technology is the fastest and most effective way to

reduce cost and man power required for maintenance

of these systems. The monitoring and configuration of

EH system over WSN has following advantages Used

for remote monitoring of renewable harvested energy.

Remote configuration for setting charging threshold

limits of storage device that in turn reduce cost and

man power required for manual work. The

overcharging / deep discharge alerts reduces the

storage device replacement and maintenance cost.

Particularly suitable for industrial monitoring

application in distributed power generation plants.

Fig. 1: System Architecture of WSN for Monitoring of EH System

Most recently the wireless communication ability

has made the embedded applications world by leading

to the development of sensor networks. In any

monitoring and control application the sensor nodes is

composed of small wireless sensor node. These nodes

are randomly deployed and distributed in a designated

region where humans may have limited access to the

area/location. This means that once sensor nodes are

deployed it should be able to self-organize into a

wireless network to identify its connectivity and

Narayanaswamy


213

distribution without human intervention. The typical

arrangement of WSN architecture for collecting

information about the region and transmits the

monitoring information to the centralized monitoring

station / base station (BS) through multi-hop

communications. Then the centralized monitoring

station then sends the data/information to any remote

user for monitor and control application.

Industrial Control and Monitoring: Wireless

sensors can be used to monitor the state of machinery,

measure the performance of machine or to

environmental parameters in harsh environments. With

this remote monitoring capability the maintenance cost

can be reduced and also deployment cost required for

wiring connections to these sensing devices is reduced.

2. LITERATURE REVIEW

In literature review the previous research efforts to

understand the concepts in the areas of monitoring and

control application using WSN. In remote monitoring

application, water environment monitoring plays an

important role in environment protection and

management in the field of large-scale water quality

measurement. The traditional method requires man

power to collect the water sample and perform manual

testing in the laboratory. This is a labor intensive and

time-consuming task to meet the water environment

protection and management objective these issues

wrwe addressed by the authors (Jin et al., 2010).

The author (Biyabani, 2009) proposes design

considerations for an embedded WSN for periodic

monitoring of civil infrastructure using an on chip

integration of solar energy harvesting super-capacitors

for extra power along with batteries powered source

when mains power is not available.

The Energy harvesting setup with six hours of

adequate sunlight to harvest solar power to recharge

battery to its full capacity every day increases the

lifetime of the Wireless networks (Musiani et al.,

2007) explored the active sensing platform for wireless

structural health monitoring of batteries were

discussed. (Piorno et al., 2009) Management of solar

harvested energy in actuation-based and event-

triggered the systems. (Staszewski, W. J., Lee, et al.,

2004) Structural health monitoring using scanning

laser vibrometry concept were presented.(Steck, 2009)

Energy and Task Management in Energy Harvesting

Wireless Sensor Networks for Structural Health

Monitoring were dealt .

(Taylor et al., 2009) A mobile-agent based wireless

sensing network for structural monitoring applications,

has explored scenarios in which nodes can harvest

energy from their environment (Jiang et al., 2005)

perpetual environmentally powered sensor networks.

Existing approaches to the problem of dynamic duty-

cycling of nodes with energy harvesting capabilities

attempt to model the energy source and adjust the

node’s duty cycle in anticipation of expected incoming

energy or lack thereof (Voigt et al., 2003) Utilizing

solar power in wireless sensor networks and health

monitoring is carried out.

Lifetime Maximization in Clustered WSN: The

sensor nodes are grouped into cluster and it comprises

of Cluster Heads (CH) and Non-Cluster Heads

(NCH). The cluster head processes the data of each

non cluster heads and transmit the whole cluster

information to base station. The energy consumed by

the cluster head to do the processing is higher

compared to non cluster heads thereby it drains its

battery energy quickly. Thus the authors (Zhang et

al., 2011). Presented the single cluster algorithm for

life time optimization in homogeneous WSN with one

solar powered sensor node. In this technique the

cluster heads listen on the network for the non cluster

head nodes to transmit the data in the specified time

slot. On the receipt of the NCHs data, cluster heads

process and routes through the shorter distance energy

harvesting node to relay information to the Base

Station (BS) thereby increase the network life time

and minimizing the energy required by cluster head.

Monitoring systems are widely used in industrial

applications and the review shows how wireless

sensors can contribute to monitoring systems;

however it does not take into account the need of

intelligent wireless monitoring systems that can

minimize the cost required for maintenance increase

the operational efficiency of the system i.e. monitored.

3. MONITORING EH SYSTEM

Energy harvesting is a process by which energy is

derived from external sources (e.g., solar power,

thermal energy and wind energy) captured, and stored

in energy storage devices Example: lithium-ion (Li-

ion)/ nickel–cadmium (NiCd) Battery.

The monitoring of any energy harvesting system

plays an important role to provide reliable operation

of the systems that utilizes the energy from energy

harvesting storage device, it is important to know the

factors that affect the storage device (battery) life and

the amount of energy remaining in the storage devices

at any point of time. The factors that affect the storage

devices (battery) life are (a) Deep discharge of the

energy reduces the life of the battery; (b) Frequent

overcharging has a damaging effect on the battery.

http://en.wikipedia.org/wiki/Energy

http://en.wikipedia.org/wiki/Solar_power


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4. SYSTEM ARCHITECTURE FOR WSN FOR

MONITORING AND CONFIGURATION OF EH SYSTEM

Figure 1 forms the basic setup of WSN and the

communication between monitoring unit, master and

slave node forms WSN for any monitoring

application. In this case WSN for monitoring of

energy harvesting system the output of the system i.e.

to be monitored is given as input to signal

conditioning circuitry

5. DESIGN SPECIFICATION

The monitoring and configuration of EH system

consists the following stages:

(a) Monitoring unit needed to monitor the EH

system

(b) Monitoring unit integrated with wireless slave

node required to transmit the monitoring data to the

master over WN

(c) Master node communicates with the slave node

to gather data and present them to the end user over

USART communication

(d) A user interface over HyperTerminal for

displaying data and giving the user the ability to

configure the EH System over WN

5.1. Development of WSN Monitoring and

Configuring EH System

The hardware development of the system mainly

includes Monitoring slave sensor node and sink node.

They are composed of the control and wireless

communication module and the related functional

module.

5.2. The Monitoring Slave Sensor Node

Figure 2 shows the hardware structure of sensor node.

It mainly consists of monitoring and control unit, and

wireless communication module.

Fig. 2: The Structure of WSN for Monitoring of EH System

5.3. Monitoring and Control Unit

The characteristics of the system that is to be

monitored are voltage / state of charge in the EH

system’s storage device. In monitoring and control unit

block the microcontroller has the limitation on the

inputs that can be given to it. The monitoring systems

voltage is stepped down using signal conditioning

circuit then its output is given as the voltage input to

the 10 bit Analog to Digital Converter (ADC) of the

microcontroller. The value from the signal

conditioning circuit and ADC are sampled, and

processed using the microcontroller to determine the

voltage / state of charge of the system that is

monitored. This information is displayed on LCD and

also packetized, and transmitted to the master over

WN by the wireless communication module.

5.4. Control and Communication Module:

The control and communication module is the core

unit that forms slave sensor node, which is responsible

for obtaining the data from the monitoring and control

unit, and perform wireless communication with other

nodes/master using 2.4GHz IEEE 802.15.4 compliant

RF transceiver. Below are the following task that are

initiated by the slave node, when the master node

sends a data request to the slave node

Receive and decode the master request

Send command to the monitoring unit

Receive the data over USART communication

line.

Packetizes the data with IEEE802.15.4

compliant frame and transmit over WN.

Go back to monitoring mode and put the RF

radio in receiver mode

Narayanaswamy


215

5.5. The Master Node

The key device is Zigbee module with 2.4GHz

IEEE802.15.4 compliant low power consumption

Yoda RF transceiver with an enhanced USART

interface and microcontroller from Si2 Microsystems

Pvt. Ltd. Figure 5 shows the master node structure,

where the Zigbee acts as main communication module

to transmit the data request to the slave nodes based on

the Zigbee protocol for monitoring of EH system.

Sink / Master Node

RF wireless

ModuleMicrocontroller USART

Host User

Power Supply

Fig. 3: The Structure of Master Node

5.6. Software Design of WSN for Monitoring and

Configuration of EH System

The self-organization and data transmission of the

wireless sensor networks are based on Zigbee protocol

stack. The Zigbee IEEE 802.15.4 protocol on 2.4GHz

(license free for personal area network) is most

suitable for the short range data communication and

provides good coverage for industrial monitoring

applications.

5.7. Establishing WSN over Master Node

Figure 4 shows the logic flow to form WSN with the

slave nodes over master node. Here the master node

broadcasts association request command to all the

sensor nodes over WN and waits for a specified

interval of time for the nodes to respond back. The

master node saves the address of all nodes to form a

wireless communication network for monitoring

application. If the slave node doesn’t respond then the

network search time is incremented and trial counter is

incremented. If number of trials is completed then the

master node goes into the power saver mode and puts

the radio into sleep mode. The master has a wakeup

counter to wake up the radio and start the new search

to establish the WSN.

5.8 Event based algorithm with Periodic Sleep

and Communicate Mode

The event based algorithm is an energy efficient

algorithm by configuring periodic sleep and

communicate method, the RF radio is put to sleep and

periodically the radio is made to wake and transmit the

data to master thereby minimizing the power

consumption and increasing the WN life time.

Figure 7 shows the logic flow diagram of event

based algorithm with periodic wake up and

communicate mode. In this algorithm certain events

are initially configured before deployment in the EH

monitoring system by setting up the battery threshold

levels for certain types of events. When the events

occur in the node or the node sleep time is finished the

monitoring node sends a wake up command to the RF

module and establishes the wireless communication to

notify the monitoring status of EH System to the

master. Thus by increasing the sleep time of the slave

node and wakeup the RF slave node on event

minimizes the energy consumption that is required for

data communication.


216

Fig. 4: Flow chart for Establishing WSN over Master Node

Fig.5 Flow chart for Event Based Algorith with Periodic Sleep and Communicate Mode

5.9. Remote Configuration Capability

The Master can configure the slave node remotely to

set the upper and lower limit threshold parameters of

EH system for monitoring purposes, if the data sensed

by the monitoring unit is out of the limit it triggers the

alarm.

Narayanaswamy


217

Fig. 6: Flow chart Over the Air Remote Configuration of EH System

Figure 6 shows the logic flow of the remote

configuration of EH system over master, the slave

receives and decodes the configuration parameters, and

then sends a command to the monitoring unit to update

the new monitoring configuration parameter of the EH

system. The monitoring unit then updates with the new

parameters and starts monitoring. This design

eliminates the manually updating monitoring

parameters and also minimizes the cost involved for

manual work.

6. IMPLEMENTATION

Figure 7 shows the hardware prototype setup for WSN

for monitoring and configuration EH System. The

following are steps are initiated for monitoring the EH

System over WSN

(a) Monitor the EH System Continuously

(b) Upon monitoring data request from master node

pack the monitoring data in MAC frame and Transmit

(c) Master receives the monitoring data, decode and

present the monitoring parameter of the EH System to

user over host HyperTerminal

(d) Monitor the data on Hyper Terminal for over

charge alert and initiate corrective measure to

minimize the damage to the storage devices

Fig. 7: Hardware Setup for Monitoring & EH System

7. RESULTS

The Figure 8 shows the monitoring of EH system over

WSN. The master sends a request to the monitoring

slave and the slave nodes send the data of the battery

voltage of the energy harvest device. This enables to

monitor the energy stored in the harvesting devices

and also enables better utilization of other system to

utilize the harvested energy.


218

Fig. 8: Monitoring of EH System Over Master Console Utility

Fig. 9: Receiveing Alerts Over Master Console Utility

Figure 9shows the remote configuration feature

over master console utility that enables to update the

threshold limits over the air and the Figure 12 shows

the monitoring of EH system using event based

algorithm, where upon an event of over charge or

sudden discharge the slave node sends an alert

message over WN.

8. MONITORING ANALYSIS

To demonstrate WSN for monitoring EH system, the

experiment has been set up using monitoring unit,

slave node and master node using Zigbee modules and

the experiment had been carried out on a sunny day

using a solar panel that outputs 18 volts with constant

current not exceeding more than 1200mA and Li-ion

battery had been used as EH storage device. The EH

system data is captured by the monitoring unit and the

master request the data at every three minutes form

slave and logged for future analysis. The battery

characteristic graph below shows the monitoring data

collected from EH system over WN the resulting 60

minute for charging and 66 minutes for discharge at

different constant discharge currents and the variation

of voltage with respect to time is obtained and

discussed.

8.1. Monitoring of Storage Device during Energy

Harvesting

To determine the time required to fully charge / state

of charge, two trials have been conducted one is with

Narayanaswamy


219

load and other is without the load connected to the EH

system and the graph is plotted for monitoring data

that is collected over WN from EH system for the

resulting 60-minute charge time. From the Figure 10 it

can be observed that the voltage of the battery

increases with the time. When the load is connected

the time required to charge increases compared to that

without the load.

Fig. 10: Battery Characteristics while Harvesting the Energy

Fig. 11: Battery Characteristic During Discharge

8.2. Monitoring of Storage Device during

Discharging

Figure 11 gives the variation of voltage in battery with

time when the battery is discharged at a constant

current of 800mA and 1A. From the characteristics

Figure 11 it is seen that the terminal voltage of the

battery decreases with time till a certain voltage. The

battery is considered to be depleted fully when the

terminal voltage reaches 6200mV.

The experiment shows that when higher load is

connected and the load is kept continuously actives

results in decrease in battery life time and upon

completely depleted the load becomes inactive.

9. CONCLUSION

The proposed method provides low power monitoring

unit, master and slave nodes for monitoring of EH

system by establishing the communication between

master-slave over WSN with an easy to install and

setup the monitoring of EH system. The monitoring

system provides reliable measurements in a periodic

time interval and the system provides remote

configuration capability that is capable to configure

EH system to provide over charged / discharge alert to

minimize the damage to the EH storage devices and

also reduces the man power and cost required to set

the EH system threshold limit manually. To assure

efficient working operation of monitoring unit over

WSN allows remote configuration capability to put


220

the monitoring unit in low power mode to extend the

life of the monitoring system / slave node. Further

improved by

(a) Multiple numbers of master/slave nodes can be

used for better performance.

(b) This monitoring alert can be further enhanced to

have a graphical user interface over internet to monitor

all system parameters online.

(c) The system can be made still energy efficient

with the use of path selection or cluster head selection

algorithm to increase the WN life time

REFERENCES

Jin N, Ma R, Lv Y, Lou X (2010). A Novel Design of

Water Environment Monitoring System Based

on WSN. IEEE Computer Design and

Applications, (2): 593-597.

Zhang P, Xiao G, Tan H (2011). A Preliminary Study

on Lifetime Maximization in Clustered

Wireless Sensor Networks with Energy

Harvesting Nodes. Singapore : IEEE

Communication.

Biyabani J (2009). Infrastructure Monitoring Smart

Wireless Sensor Network with Solar Energy

Harvesting. 2009 IEEE Communication, 1-4.

Musiani D, Lin K, Rosing TS (2007). Active sensing

platform for wireless structural health

monitoring. In IPSN ’07: Proceedings of the 6th

international conference on Information

processing in sensor networks, 390–399. ACM,

New York, NY, USA.

Piorno JR, Bergonzini C, Lee B, Rosing TS (2009).

Management of solar harvested energy in

actuation-based and event-triggered systems.

4th Annual Energy Harvesting Workshop.

Staszewski WJ, Lee BC, Mallet L, Scarpa F (2004).

Structural health monitoring using scanning

laser vibrometry: I. lamb wave sensing. Smart

Material Structures, 13: 251–260.

Steck J (2009). Energy and Task Management in

Energy Harvesting Wireless Sensor Networks

for Structural Health Monitoring. Master’s

thesis, UCSD. Advisor - Tajana Rosing.

Taylor SG, Farinholt KM, Flynn EB, Figueiredo E,

Mascarenas DL, Moro EA, Park G, Todd MD,

Farrar CR (2009). A mobile-agent based

wireless sensing network for structural

monitoring applications. Measurement Science

and Technology, 20(4): 045201 (14pp).

Jiang X, Polastre J, Culler D (2005). Perpetual

environmentally powered sensor networks. in

IEEE Information Processing in Sensor

Networks, 2005, pp. 463–468.

Voigt T, Ritter H, Schiller J (2003). Utilizing solar

power in wireless sensor networks. in The 28th

Annual IEEE Conference on Local Computer

Networks (LCN), Bonn/Konigswinter,

Germany.

Narayanaswamy


221

K.V.Narayanaswamy received his Bachelor and Post graduate degree in Electrical Engineering from

Bangalore University, and Ph.D degree in Electrical & Electronics Engineering, Specialised in

Wireless Communications and Networks from Visvesvaraya Technological University, Belgaum,

Karnataka, India. He has more than 22 Years of Teaching & Research experience in the field of

Electrical, Electronics & Telecommunication Engineering. His research interests are in the areas of

next-generation wireless communication and networks, Mobile Ad-hoc & wireless sensor networks,

Advanced optical network design, automotive communication protocols and standards. Carried

several research, consultancy and funded projects. Delivered number of corporate trainings in India

and abroad, Published more than 16 papers in peer reviewed international journals including IEEE,

IJCA, etc., and several conference papers.


ISSN: 2322-4541; ©2013 IJSRPUB


222



Alireza Panjsetooni1,2,

*, Norazura Muhamad Bunnori1, Tze Liang Lau

1

1School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia (USM), Seri Ampangan, Seberang Perai

Selatan, 14300 Nibong Tebal, Pulau Pinang, Malaysia 2Bakhtar institute of higher education, Ilam, Iran

*Corresponding Author: E-mail: [email protected]


Abstract. Acoustic emission (AE) is an important nondestructive evaluation (NDE) technique used in the field of structural

engineering. In this study AE technique with a new approach was employed to investigate the process of fracture formation in

reinforced concrete structure. A number of reinforced concrete (RC) frames were tested under cyclic load and were

simultaneously monitored using AE. The AE test data using intensity analysis method were analyzed. This is based on

calculating two values called the historic index (HI) and severity (Sr). The results showed that HI and Sr increase with

increasing of loading cycle and trend of HI and Sr showed that these parameters are able to indicate the levels of damage. Also,

the results indicated that AE can be considered as a viable method to investigate the process of fracture formation in reinforced

concrete structure.

Key words: Reinforced concrete; Acoustic emission; nondestructive evaluation technique; AE source location; Intensity

analysis

1. INTRODUCTION

The AE technique is one of the non-destructive

evaluation (NDE) techniques that have been

considered as the prime candidate for damage

monitoring in loaded structures and structural health

(Surgeon and Wevers, 1999). This technique is a

useful testing tool for examination of the behavior of

materials deforming under stress real time(Nair and

Cai, 2010). AE technique have been used in the field

of reinforced concrete structure for investigation

process of damage in both case local and global

monitoring (Panjsetooni and Bunnori, 2013).

The primary sources of acoustic emission in

concrete structures are numerous and include cracking

of the concrete, rubbing of crack surfaces during crack

closure, de-bonding of the reinforcing steel from the

surrounding concrete (Pollock, 1981). The main goal

of AE monitoring in structures is to detect, source, and

assess the intensity of damage(Holford and Lark,

2005).

AE data can be evaluated by means of several

methods. The Intensity analysis is a significant

method for analysis of AE signals. This technique has

already been success- fully applied to FRP and metal

piping system evaluations(Nair and Cai, 2010) . Also,

a few works was found that IA method has been used

for evaluation of the RC beam such as (Golaski et al.,

2002)and (Proverbio, 2011)

In main objective of this current study was

evaluation of damage using Intensity analysis method.

Commonly, previous works focused on local

evaluation of RC beams using Intensity analysis

method. However in this research, suitably of

Intensity analysis method for global evaluation of RC

frame was investigated.

2. METHODOLOGY

2.1. Intensity analysis

Intensity analysis (IA) evaluates the structural

significance of an AE event and the level of

deterioration of a structure by calculating two values

called the historic index (HI) and severity

(Sr)(Proverbio, 2011). The HI compares the signal

strength of the most recent emissions to the signal

strength of all emissions (Degala et al., 2009). Also,

HI a measure of the changes in signal strength

throughout the test which is an analytical method for

estimating the changes of slop in cumulative signal

strength against time(Proverbio, 2011) . The Severity

index, which is defined as the J largest signal strength

emissions received at a sensor (Degala et al., 2009).

HI is calculated using the following formulas

(Blessing et al., 1992).

HI= N/ (N-K) × ∑ ∑

(1)

Where N is number of hits up to and including

time, K is an empirical constant and is signal

mailto:[email protected]

Panjsetooni et al.


223

strength of ith hits. K is constant based on material.

For concrete, N<50, K=0 ; 51<N<200, K=N-30;

201<N<500, K=0.85N; and N>501, K=N-75 as well

as J valus for N<50, J=o and N>50 J=50 (Golaski et

al., 2002) .

(

) ∑

Where, is the signal strength of the hit, J

is an empirical constant based on material and

based on magnitude of signal strength.

3. EXPERIMENTAL PROCEDURE

3.1. Material details

A series of experiments was conducted on reinforced

concrete (RC) frame. A total of five RC frame

specimens were built. The dimension of RC frames,

were length of 2000mm, height of 1000mm and crocs

section of 250x250 mm. The water to cement ratio

was 0.5 and the material proportions were 1:3:4:0.6 by

weight of cement, sand, aggregate and water

respectively. The average compressive strength of

concrete at 28 days was 240Mpa.Figure 1 shows the

detail and dimension of RC frame specimens.

Fig. 1: Detail and dimension of RC frame specimen

3.2. Test monitoring using AE technique

A total of five RC frame specimens described earlier

were tested under loading cycle. In order to perform

acoustic emission monitoring, an eight channel AE

system (DISP-8PCI) manufactured by Physical

Acoustics Corporation (PAC) was employed. Four

R6I sensors with the resonance frequency of

approximately 60 kHz were used. Figure 2 shows

sensor arrangements for the three point bending test.

The AE systems hardware was set up was threshold

level of 45dB for all channels in order to avoid the

possibility of noise effect. The cyclic load pattern was

determined. The load applied at one at mid span of the

RC frame specimens. The load was applied in 10kN

steps at mid span of RC frame. The load was applied

from 0.5kN to maximum of each loading cycle (10kN

increment) and held constant for one minute. Then,

the load was unloaded from maximum of each loading

cycle to 0.5kN and was held for 2 minutes. The test

was monitored by AE throughout the test. The

measurement include load, mid span deflection and

AE data were recorded continuously during the three

point bending test. 4. RESULTS ANALYSIS AND DISCUSSIONS

4.1. Responses of test RC frame to cyclic loading

The RC frames described early were tested under

loading cycle. Figure 3 shows a typical cracks

development in the RC frames specimen. The

behaviour of all RC frames under loading cycle can be

divided into seven stages of failure namely:(I)Micro-

cracking at the mid span of RC frame (II) First

flexural cracks at mid span of RC frame (III)

distributed flexural cracks at the mid span of RC

frame (IV) first cracks at the BEAM-COLUMN

CONNECTION ZONES (V)Distributed cracks at

BEAM-COLUMN CONNECTION ZONES (VI)

Damage localization at the BEAM-COLUMN

CONNECTION ZONE (VII) Failure at beam-column

connection zone.


224

Fig. 2: Sensor arrangements for the three point bending test

Fig. 3: Photographs of development of cracks in RC frame specimen

4.2. Intensity Analysis

The AE data obtained in test was used in order to

carry out Intensity Analysis (IA). The maximum of

Severity (Sr) and Historic Index (HI) for all channels

were calculated. These results are summarized in

Table 1 and 2. Also, Figure 4 shows the maximum

value of Sr and HI against loading cycle number for a

sample of RC frame specimen. Data points shows that

the maximum Sr and HI are increased with increasing

of damage. Data points show that in stage micro-

cracks, initiate cracks and distribution of cracks in

mid-span of beam that HI is low level and without

significant changes. Also, data points indicate that in

stage initiate cracks and distribution of cracks in beam

column connection, HI is high level with significant

changes.

HI is a measure of the changes in signal strength

throughout the test(Proverbio, 2011) . Also, a

significant increase in HI can indicate the onset of

more serious structural damage as the loading

progresses (Lovejoy, 2008). Furthermore, The AE

knees may be used to identify possible damage

mechanisms and to locate the onset of failure

(Gostautas et al., 2005)

The results of this study show that early stage of

failure that load cycles is less than 50% ultimate load,

HI haven’t significant change. Also, the results

indicated that is in stage in stage initiate in beam –

column until specimen failure that that load cycles is

more than 50% ultimate load, HI have significant

changes. Thus, using the interpretation described

above it is clear to see that HI can indicate serious

structural damage in RC frame.

With respect to Sr that is average signal strength,

the value of Sr can be used to show the level of

damage. The primary advantage of using both HI and

Sr in this application is the high sensitivity to stage of

failure.

Figure 5 shows a intensity chart for a sample RC

frame (SPRCF1). Data point indicate that the points

relative to the first until sixth loading cycle ( micro

Panjsetooni et al.


225

cracks behavior stage) fall in the area of low damage

level and the point relative to the seventh and ninth

loading cycle ( initial cracks stage in mid span of

frame) falls in the area of moderate. Furthermore, all

of the points relative to the tenth loading cycle until

twelfth loading cycle (Damage localization until

failure in beam-column connection) fall in the area of

high damage level.

The results for RC beam and frame show that three

levels of damage (heavy, moderate and low) can be

recognised using intensity chart. Data points show that

stages of damage is recognizable using IA chart.

Table 1: a summary of maximum Historic index during cycle loading

Cycle no. Stage of

failure.

Maximum Severity Index

SPRCF1 SPRCF2 SPRCF3 SPRCF4 SPRCF5

C1 I 1.47E+06 1.24E+06 3.25E+06 1.35E+06 1.01E+06

C2 I 2.95E+06 2.10E+06 6.05E+06 1.68E+06 1.25E+06

C3 I 6.58E+06 4.84E+06 1.37E+07 4.15E+06 3.10E+06

C4 II 1.04E+06 1.04E+06 2.48E+06 1.39E+06 1.04E+06

C5 III 5.40E+06 4.96E+06 1.24E+07 6.07E+06 4.53E+06

C6 III 1.55E+07 1.29E+07 3.40E+07 1.37E+07 1.02E+07

C7 IV 1.94E+07 1.58E+07 4.22E+07 1.65E+07 1.23E+07

C8 V 4.02E+07 2.54E+07 7.88E+07 1.43E+07 1.07E+07

C9 V 4.46E+07 7.07E+07 1.38E+08 1.30E+08 9.68E+07

C10 V 6.87E+07 5.39E+07 1.47E+08 5.23E+07 3.90E+07

C11 VI 7.08E+07 6.01E+07 1.57E+08 6.62E+07 4.94E+07

C12 VII 2.32E+08 1.40E+08 4.46E+08 6.41E+07 4.79E+07

Table 2: a summary of maximum historic index during cycle loading

Cycle no. Stage of failure. Maximum Historic Index

SPRCF1 SPRCF2 SPRCF3 SPRCF4 SPRCF5

C1 I 2.33E+00 4.09E+02 4.94E+02 1.09E+03 8.16E+02

C2 I 1.10E+02 6.11E+02 8.66E+02 1.49E+03 1.11E+03

C3 I 3.48E+02 1.16E+03 1.81E+03 2.64E+03 1.97E+03

C4 II 5.90E+02 1.02E+03 1.94E+03 1.96E+03 1.46E+03

C5 III 3.40E+02 7.88E+02 1.35E+03 1.66E+03 1.24E+03

C6 III 1.13E+03 1.29E+03 2.90E+03 1.94E+03 1.45E+03

C7 IV 6.73E+03 3.97E+03 1.28E+04 1.62E+03 1.21E+03

C8 V 4.41E+03 5.23E+03 1.16E+04 8.11E+03 6.05E+03

C9 V 8.45E+03 8.38E+03 2.02E+04 1.11E+04 8.30E+03

C10 V 5.47E+03 8.88E+03 1.72E+04 1.65E+04 1.23E+04

C11 VI 1.41E+04 9.42E+03 2.82E+04 6.39E+03 4.77E+03

C12 VII 3.40E+04 2.18E+04 6.70E+04 1.28E+04 9.56E+03

Fig. 4: Sr and HI against loading cycle number –SPRCF1


226

Fig. 5: Intensity chart –SPRCF1

5. CONCLUSIONS

This paper provides the results from tests on RC

frame under loading cycle and was monitored by AE

throughout the test. On the basis of AE activities, the

analysis of signal characteristics using intensity

analysis and with regard to damage levels, the

conclusions are presented below:

(1) Three levels of damage in concrete structure

can be identified using intensity analysis; (2) The

trend of historic and severity index during loading

cycle showed that these parameters are strongly

sensitive with cracks growth in RC frame specimens

and were able to indicate the levels of damage; (3)

Results showed that AE can be considered as a viable

method to predict the remaining service life of

reinforced concrete.

Acknowledgment

The authors would like to thank Universiti Sains

Malaysia (USM) for providing support through the

short term Grant [304/PAWAM/6039047]

REFERENCES

Astm E (2006). 06a Standard Test Method for

Measurement of Fracture Toughness. Annual

Book of Astm Standards. Philadelphia PA:

American Society for Testing and Materials.

Blessing J, Fowler T, Strauser F. (1992). Intensity

analysis. Proc., 4th Int. Symp. on Acoustic

Emission from Composite Materials. American

Society for Nondestructive Testing.

Degala S, Rizzo P, Ramanathan K, Harries KA

(2009). Acoustic emission monitoring of CFRP

reinforced concrete slabs. Construction and

Building Materials, 23: 2016-2026.

Golaski L., Gebski P, Ono K (2002). Diagnostics of

reinforced concrete bridges by acoustic

emission. Journal of acoustic emission, 20: 83-

89.

Gostautas RS, Ramirez G, Peterman RJ, Meggers D

(2005). Acoustic emission monitoring and

analysis of glass fiber-reinforced composites

bridge decks. Journal of bridge engineering, 10:

713-721.

Holford K, Lark R (2005). Acoustic Emission Testing

Bridges.

Lovejoy SC (2008). Acoustic emission testing of

beams to simulate SHM of vintage reinforced

concrete deck girder highway bridges.

Structural Health Monitoring, 7: 329-346.

Nair A, Cai C (2010). Acoustic emission monitoring

of bridges: Review and case studies.

Engineering structures, 32: 1704-1714.

Panjsetooni A, Bunnori NM (2013). Damage

Evaluation Assessment of Reinforced Concrete

Structure using b-value and Damage Parameter

Analysis of Acoustic Emission Signals.

International Journal of Scientific Research in

Knowledge (IJSRK), 1: 44-50.

Pollock A (1981). Acoustic emission amplitude

distributions. International Advances in

Nondestructive Testing., 7: 215-239.

Proverbio E (2011). Evaluation of deterioration in

reinforced concrete structures by AE technique.

Materials and corrosion, 62: 161-169.

Surgeon M, Wevers M (1999). Modal analysis of

acoustic emission signals from CFRP

laminates. NDT & E International, 32: 311-322.

Panjsetooni et al.


227

Alireza Panjsetooni was born in Western area of Iran on 2rd January 1976. His first degree at University

Tabriz in Bach of Civil Eng (Hons) 2000. Then he continued deeply in Master of earthquake

Engineering (M.Struct) at Universiti Tehran in 2008 and currently his pursuing in PhD level at Universiti

Sains Malaysia in Structural Health Monitoring.

Norazura Muhamad Bunnori (PhD) has been involved in Acoustic Emission (AE) technique since 2004

while she was pursuing her PhD study at Cardiff University, Wales, UK. She was graduated from

Cardiff University in 2008 and continues with the AE research area in Universiti Sains Malaysia (USM),

Malaysia. Currently she is working as a Senior Lecturer at School of Civil Engineering, Universiti Sains

Malaysia (USM) since 2009. The research covered several topics of AE applications and analysis

(quantitative and qualitive). The aim is to continue the AE study especially in Structural Health

Monitoring (SHM) research area and to discover more in this potential area. The passion towards AE is

deep and she believes that there are a great number of information can be studied and discovered with

this tool.

Dr. Lau is a lecturer at School of Civil Engineering, Engineering Campus, University Sains Malaysia.


ISSN: 2322-4541; ©2013 IJSRPUB


228


Time-Dependent Creep Analysis of Rotating Thick-Walled Cylindrical Pressure

Vessels under Heat Flux

Mohammad Zamani Nejad*, Mosayeb Davoudi Kashkoli

Mechanical Engineering Department, Yasouj University, P. O. Box: 75914-353, Yasouj, Iran

*Corresponding Author: [email protected]; [email protected]


Abstract. This paper presents a closed-form analytical solution for time-dependent creep stresses and displacements of

isotropic and homogeneous rotating thick-walled cylindrical pressure vessels under heat flux. Assuming that the thermoelastic

creep response of the material is governed by Norton’s law, using equations of equilibrium, strain-displacement and stress-

strain relations, a differential equation for the displacement rate is obtained and then the stress rates are calculated. When the

stress rates are known, the stresses at any time are calculated iteratively. The analytical solution is obtained for the conditions

of plane strain and plane stress. The thermal loading is as: inner surface is exposed to a uniform heat flux, and the outer surface

is exposed to an airstream. Following this, profiles are plotted for the radial stress, circumferential stress and axial stress as a

function of radial direction and time for different values of angular velocity. This analytical solution can be used easily to study

the dependence of the stresses on time and temperature. The values used in this study are arbitrary chosen to demonstrate

the effect of creep on displacements, and stresses distributions.

Key words: Thick Cylindrical Pressure Vessel, Heat Flux, Rotating, Creep, Time-Dependent

1. INTRODUCTION

Many components are used in modern technologies

such as nuclear, aircraft, space engineering and

pressure vessels are subjected to high temperature

environment and complex loading conditions over a

long time. Therefore, creep stress analysis of these

components is very important in these applications.

Weir (1957) investigated creep stresses in

pressurized thick walled tubes. Considering large

strains, Rimrott and Luke (1961) obtained the creep

stresses of a rotating hollow circular cylinder made of

isotropic and homogeneous materials. Bhatnagar and

Gupta (1662) obtained solution for an orthotropic

thick-walled internally pressurized cylinder by using

constitutive equations of anisotropy creep and

Norton’s creep law. Assuming the plane strain

condition, Bhatnagar et al. (1984) obtained analysis of

an internally pressurized, homogeneous, orthotropic

rotating cylinder subjected to a steady state creep

condition. In another study, considering the effect of

anisotropy on stress and strain, creep analysis of

thick-walled orthotropic rotating cylinders has been

investigated by Bhatnagar et al. (1986). Yang (2000)

obtained an analytical solution to calculate thermal

stresses of thick cylindrical shells made of

functionally graded materials with elastic and creep

behavior. Gupta and Pathak (2001), studied thermo

creep analysis in a pressurized thick hollow cylinder.

Hoseini et al. (2011) presented a new analytical

solution for the steady state creep in rotating thick

cylindrical shells subjected to internal and external

pressure. Assuming that the creep response of the

material is governed by Norton’s law, Zamani Nejad

et al. (2011) presented a new exact closed form

solution for creep stresses in isotropic and

homogeneous thick spherical pressure vessels. In

another study, assuming the mechanical properties

vary nonlinearly in the radial direction, Zamani Nejad

et al. (2013) obtained a new exact solution for steady

state creep stresses of pressurized thick spherical

shells made of functionally graded materials. In this

article, assuming that the thermo-creep response of the

material is governed by Norton’s law, an analytical

solution is presented for the calculation of time-

dependent creep stresses of isotropic and

homogeneous rotating thick-walled cylindrical

pressure vessels under heat flux.

2. SOLUTION FOR LINEAR ELASTIC

BEHAVIOR OF ROTATING THICK

CYLINDRICAL PRESSURE VESSEL

For the stress analysis in rotating cylinder, having

material creep behavior, the solutions of the stresses at

a time equal to zero (i.e. the initial stress state) are

needed, which correspond to the solution of materials

with linear elastic behavior. In this section, equations

to calculate such linear stresses in rotating cylinder

analytically will be given briefly for two cases: (a)

plane strain; (b) plane stress. Consider a thick-walled

cylinder with an inner radius a , and an outer radius

Zamani Nejad and Davoudi Kashkoli


229

b , subjected to internal pressure iP and external

pressure oP that are axisymmetric, and rotating at a

constant angular velocity about its axis (Fig. 1).

2.1. The case of plane strain

The heat conduction equation for the one-

dimensional problem in cylindrical coordinates

simplifies to:

0T

rr r

(1)

where T T r is temperature distribution in the

thick cylindrical pressure vessel. The general solution

of Eq. (1) is:

1 2T r A lnr A (2)

The boundary conditions for when that inner

surface is exposed to a uniform heat flux aq , and the

outer surface is exposed to an airstream temperature,

are as follows:

aT q , r a

T h T T , r b

dTT

dr

(3)

Here , T and h

are thermal conductivity,

temperatures and heat transfer coefficient of the

surrounding media, respectively. Substituting Eq. (2)

into Eq. (3) yields:

1

2

q

q q

aqA

aq aqA T lnb

bh

(4)

Therefore:

q qaq aq rT r T ln

bh b

(5)

The displacement in the r-direction is denoted by

ru . Three strain components can be expressed as:

rrr

du

dr (6)

ru

r (7)

0zz

(8)

where rr ,

and zz are radial, circumferential

and axial strains. The stress-strain relations for

homogenous and isotropic materials are:

1

1 1 2 1rr rr

E

(9) 1

1T

1

1 1 2 1rr

E

(10) 1

1T

(11) zz rr E T

where rr , and

zz are radial, circumferential

and axial stresses, respectively. Here E , and are

the Young's modulus, Poisson's ratio and thermal

expansion coefficient, respectively.

Fig. 1: Geometry and Boundary Conditions of the cylinder

The equilibrium equation of the rotating cylindrical

pressure vessel, in the absence of body forces, is

expressed as:

2rr rrdr

dr r

(12)

where is density.


230

Using Eqs. (5-12), the essential differential equation

for the displacement ru can be obtained as:

2

2

1r rd u du dln E

dr dr r dr

1

1

ru dln E

r dr r

1

1

d dT dT T ln E

dr dr dr

2

1 1 2

1r

E

(13)

For a homogenous and isotropic material, Young's

modulus, Poisson's ratio , and the thermal expansion

coefficient ,are constant, therefore, Eq. (13) on

simplifying yields: 2

2 2

1r r rd u du u

dr r dr r

1

1

dT

dr

2

1 1 2

1r

E

(14)

The general solution of the displacement ru is:

2

1

1

1

r

r a

Cu ( r ) C r Trdr

r r

3 2

1 1 2

8 1r

E

(15)

The corresponding stresses are:

2

1 21 2

1 1 2rr

E CC

r

2 2

2

1 3 2

1 8 1

r

aTrdr r

r

(16)

2

1 21 2

1 1 2

E CC

r

2

1

1

r

a

E TTrdr

r

2 21 2

8 1r

(17)

zz rr E T

(18)

To determine the unknown constants 1C and 2C in

each material, boundary conditions have to be used,

which are:

rr i

rr o

P , r a

P , r b

(19)

The unknown constants 1C and 2C

are given in

Appendix.

2.2. The case of plane stress

For the case of plane stress the stress-strain relations

are:

(20) 2

11

rr rr

ET

(21) 2

11

rr

ET

(22) 0zz For The case of plane stress the differential equation

for displacement ru is:

2

2 2

1r r rd u du u

dr r dr r

2

211

dTr

dr E

(23)

The solution of Eq. (23) is:

2

1

1 r

r a

Cu C r Trdr

r r

23 21

8r

E

(24)

The corresponding stresses are:

2

1 2 2

1

1 1

r

rr a

E CC Trdr

r r

2 23

8r

(25)

21 2 2

1

1 1

r

a

E CC Trdr

r r

2 21 3

8E T r

(26)

To determine the constants 1C and 2C , boundary

conditions have to be used which are the same as

those for the case of plane strain (see Eq. (19)). The

unknown constants 1C and 2C are given in Appendix.

3. SOLUTION FOR CREEP BEHAVIOR OF

ROTATING THICK CYLINDRICAL

PRESSURE VESSEL

For materials with creep behavior, we use Norton's

law (Finnie and Heller, 1959) to describe the relations

between the rates of stress (ij ) and strain ( ij ) in the

multi-axial form:

(27) 11 3

2

( N )

ij ij kk ij eff ijD SE E

(28) 1

3ij ij kk ijS

3 1

2 2eff ij ijS S



231

(29) 2 2 2

rr rr zz zz

where D and N are material constants for creep.

eff is the effective stress,

ijS is the deviator stress

tensor and rr , and

zz are respectively the

radial, tangential and axial stresses. The relations

between the rates of strain and displacement are:

(30) rrr

du

dr

(31) ru

r

and the equilibrium equation of the stress rate is:

(32) 0rrrrd

dr r

For the case of plane strain ( 0zz ), the relations

between the rates of stress and strain are:

1

1 1 2 1rr rr

E

13

2 1

( N )

eff rrD S S

(33)

1

1 1 2 1rr

E

13

2 1

( N )

eff rrD S S

(34)

where:

rr rr zz zzS S S , S S S (35)

For the case of plane stress ( 0zz ), the relations

between the rates of stress and strain are:

1

2

3

1 2

N

rr rr eff rr

ED S

(36)

1

2

3

1 2

N

rr eff

ED S

(37)

where:

rr rr rrS S S , S S S (38)

3.1. The case of zz being zero

Using Eqs. (30-35), the essential differential equation

for the displacement rate ru in thick cylindrical

pressure vessel can be obtained as: 2

2

1r rd u du d(ln E )

dr dr r dr

1ru d(ln E )

r dr r

13

2

( N )

eff rr

d(ln E )D S S

dr

13

2

( N )

eff rr

dD S S

dr

13

12

rr( N )

eff

S SD

r

(39)

where:

1

(40)

For a homogenous and isotropic material, Young's

modulus is constant, also the case of , D and N being constant is studied in this article, therefore, Eq.

(39) on simplifying yields: 2

2 2

r r rd u du u

dr rdr r

13

2

N

eff rr

dD S S

dr

131

2

N rreff

S SD

r

(41)

In general, the quantities eff , rrS and S

are

very complicated functions of the coordinate r , even

in an implicit function form. Therefore, it is almost

impossible to find an exact analytical solution of Eq.

(41). We can find an asymptotical solution of Eq.

(41). At first, we assume that eff , rrS and S

are

constant, i.e. they are independent of the coordinate r .

Then, the solution of Eq. (41) is:

121

1 3

2 2

N

r eff

Du D r D

r

2

rr

aS S r

r

2 21 2

1 2 2rr

r a aS S r lnr lna

r r

(42)

where the unknown constants 1D and 2D can be

determined from the boundary conditions. The

corresponding stress rates are:

2

1 21 2

1 2 1rr

E DD

r

13

4

N

eff rrD S S

2

21 1 2

a

r

1 2 1 2

1 2

rrS Sln r

2 2

2 2

1 2 1 2

2

a ln a a

r r

131

2

N

eff rrD S S

(43)


232

2

1 21 2

1 2 1

E DD

r

13

4

N

eff rrD S S

2

21 1 2

a

r

1 2 1 2

1 2

rrS Sln r

2 2

2 2

1 2 1 2

2

a lna a

r r

131

2

N

eff rrD S S

(44)

13

2

N

zz rr eff zzD S (45)

The boundary conditions for a cylindrical vessel

subjected to internal and external pressure are given

as:

(46) 0

0

rr

rr

, r a

, r b

Using these boundary conditions the constants 1D

and 2D are obtained:

121 2

31 2

4

N

eff

DD D

a

2 1 2 1 2rrS S

rrS S lna

131

2

N

eff rrD S S (47)

2 1

2 2 2

3

4 1 2

N

effab DD

b a

2 2

2

1 2rrS S b a

b

1

1 2 21

rrS S lna

2

2

1 21 2

2

a lnalnb

b

2

2

1 2

2

a

b

(48)

When the stress rate is known, the calculation of

stresses at any time it should be performed iteratively:

(49) 1

1

i i i i

ij i ij i ij ir,t ( r,t ) ( r,t )dt

where:

(50)

0

ik

ik

t dt

To obtain a generally useful solution, a higher

order approximation of eff ,

rrS and S should be

made:

1

effr r

eff eff

dr

drr r r r!

2

2 2

2

effr r

dr

dr r r!

3

3 3

3

effr r

dr

dr r r ...!

(51)

1

'

rrr r' '

rr rr

dS r

drS r S r r r!

2

2 2

2

'

rrr r

dS r

dr r r!

3

3 3

3

'

rrr r

dS r

dr r r ...!

(52)

1

'

r r' '

dS r

drS r S r r r!

2

2 2

2

'

r r

dS r

dr r r!

3

3 3

3

'

r r

dS r

dr r r ...!

(53)

where r is one given point in the creep layer, the

center point of the creep layer.

3.2. The case of zz

being zero

Using Eqs. (30-32) and Eqs. (36-38), the essential

differential equation for the displacement rate ru in

thick cylindrical pressure vessel can be obtained as:

2

1

2 2

3

2

Nr r r

eff rr

d u du u DS S

dr rdr r r (54)

The solution of Eq. (54) is:

121

1 3

2 2

N

r eff rr

Du D r D S S

r

1

2r ln r a lna r a

(55)

where the unknown constants 1D and 2D can be

determined from the boundary conditions. The

corresponding stress rates are:

121 2

1 3

1 1 4

N

rr eff

E DD D

r



233

1

1 11 2

rrS S aln r

r

13

2 1

N rr

eff

Sa lnaD

r

(56)

121 2

1 3

1 1 4

N

eff

E DD D

r

1

1 11 2

rrS S aln r

r

13

2

N

eff

alnaD S

r

(57)

where

1

21 2

1 3

1 4 1

N

eff rrD S SDD

b

1

1 1 22

lna lna

13

2 1

N rr

eff

SD

(58)

2 1

2 2 2

3

4

N

eff rrab D S SD

b a

1

1 12

a aln lna

b b

(59)


In the previous section, the analytical solution of time-

dependent creep stresses and displacements of

isotropic and homogeneous rotating thick-walled

cylindrical pressure vessels under heat flux and

uniform pressures on the inner and outer surfaces have

been obtained. In this section, some profiles are

plotted for the radial stress, circumferential stress and

axial stress as a function of radial direction and time

for different values of angular velocity.

A cylindrical pressure vessel with creep behavior

under internal and external pressure is considered.

Radii of the cylinder are 20a mm, 40b mm. In

addition, angular velocity varies from 600 rpm to

1200 rpm. The other data are:

°

w207GPa 0 292 43

m. CE , . ,

6 ° 810 8 10 C 1 4 10 2 25. , D . , N .

3

2 2 °

w w7798kg m 3000 6 5

m m . Ca, q , h .

25 80MPa 0MPao

i oT C , P , P

The thermal loading is as follows: inner surface is

exposed to a uniform flux, aq , and the outer surface is

exposed to an airstream at T.

4.1. The case of plane strain

The stress distribution after 10h of creeping are

plotted in Fig. (2), (3) and (4) for the stress

components rr

, and zz respectively.

According to Fig. (3) and (4), radial and

circumferential stresses for all values of are

compressive. It can be seen that radial and

circumferential stresses decreases as increases.

Fig. 2: The radial stress calculated from the asymptotic solution after 10 h of creeping

Fig. 3: The circumferential stress calculated from the asymptotic solution after 10 h of creeping


234

Fig. 4: The axial stress calculated from the asymptotic solution after 10 h of creeping

The time dependent stresses at point r=30 mm, are

plotted in Fig. (5), (6) and (7). It is clear that the

values of all three stresses are reduced over time. It is

also significant that at this radius, all three stresses are

compressive. According to Fig. (5), radial stress

decreases as increases.

Fig. 5: Time-dependent radial stress at the point r=30 mm

Fig. 6: Time-dependent circumferential stress at the point r=30 mm

Fig. 7: Time-dependent axial stress at the point r=30 mm

4.2. The case of plane stress

The stress distribution after 10h of creeping are

plotted in Fig. (8) and (9) for the stress components

rr and respectively. According to Fig. (9),

maximum value of circumferential stress occurs at the

inner radius and also all stresses are compressive for

different values of angular velocity .

The time dependent stresses at point r=30 mm, are

plotted in Fig. (10) and (11). According to Fig. (10)



235

and (11), radial and circumferential stresses are

compressive and the values of all two stresses are

reduced over time for different values of angular

velocity .

Fig. 8: The radial stress calculated from the asymptotic solution after 10 h of creeping

Fig. 9: The circumferential stress calculated from the asymptotic solution after 10 h of

creeping

Fig. 10: Time-dependent radial stress at the point r=30 mm

Fig. 11: Time-dependent circumferential stress at the point r=30 mm

5. CONCLUSION

This study, an analytical solution procedure has

developed for the analysis of an internally and

externally pressurized, isotropic homogeneous

rotating thick-walled cylindrical pressure vessels

subjected to a time-dependent thermo creep condition.

For the stress analysis in a cylindrical pressure vessel,

having material creep behavior, the solutions of the

stresses at a time equal to zero (i.e. the initial stress

state) are needed, which correspond to the solution of

materials with linear elastic behavior. The analytical

solution is obtained for the conditions of plane strain

and plane stress. For the creep material behavior, the


236

solution is asymptotic. For the stress analysis after a

long time creeping, the iterative procedure is

necessary. Norton's power law of creep is employed to

derive general expressions for stresses and strain rates

in the thick rotating cylindrical pressure vessel. The

pressure, inner radius and outer radius are considered

constant. Material properties are considered as

constant. The heat conduction equation for the one-

dimensional problem in polar coordinates is used to

obtain temperature distribution in the cylinder.

According to stress distribution after 10h of creeping

for the case of plane stress, both radial and

circumferential stresses remain compressive over the

entire cylindrical vessel radius. It must be noted that

for the case of plane stress, the maximum value of

circumferential stress at the point r=30 mm, is at a

time equal to zero (i.e. the initial stress state) and it

decreases as time increases while the maximum value

of radial stress at the point r=30 mm, is at almost

Time= 1h and it decreases as time increases.

According to stress distribution after 10h of creeping

for the case of plane strain, the maximum value of all

three stresses at the point r=30 mm, are at a time

equal to zero (i.e. the initial stress state), in other word all three stresses decrease as time increases.

6. APPENDIX

The unknown constants in Eqs. (16) and (17) are

2

1 2

1 1 2 1 2iP CC

E a

2 2

3 2 1 2 1

8 1a

E

(A1)

2

2 2 2

1i oP P abC

E b a

2

2 2

1

1 1 2

b

a

aTrdr

b a

2

23 2 1

8 1

ab

E

(A2)

The unknown constants in Eqs. (25) and (26) are

2

1 2

1 1

1

iP CC

E a

2 23 1

8a

E

(A3)

2

2 2 2

1i oP P abC

E b a

2

2 2

1

1

b

a

aTrdr

b a

2

23 1

8

ab

E

(A4)

REFERENCES

Bhatnagar NS, Gupta SK (1969). Analysis of thick-

walled orthotropic cylinder in the theory of

creep. Journal of the Physical Society of Japan,

27: 1655-1662.

Bhatnagar NS, Kulkarni PS, Arya VK (1984). Creep

analysis of an internally pressurized orthotropic

rotating cylinder. Nuclear Engineering and

Design, 83: 379-388.

Bhatnagar NS, Kulkarni PS, Arya VK (1986). Creep

analysis of orthotropic rotating cylinders

considering finite strains. International Journal

of Non-Linear Mechanics, 21: 61-71.

Finnie I, Heller WR (1959). Creep of Engineering

Materials. New York, McGraw-Hill.

Gupta SK, Pathak S (2001). Thermo creep transition

in a thick walled circular cylinder under internal

pressure. Indian Journal of Pure and Applied

Mathematics, 32: 237-253.

Hoseini Z, Nejad MZ, Niknejad A, Ghannad M

(2011). New exact solution for creep behavior

of rotating thick-walled cylinders. Journal of

Basic and Applied Scientific Research, 10:

1704-1708.

Nejad MZ, Hoseini Z, Niknejad A, Ghannad M

(2011). A new analytical solution for creep

stresses in thick-walled spherical pressure

vessels. Journal of Basic and Applied Scientific

Research, 11: 2162-2166.

Nejad MZ, Hoseini Z, Taghizadeh T, Niknejad A

(2013). Closed-form analytical solution for

creep stresses of pressurized functionally

graded material thick spherical shells.

Advanced Science Letters, 19: 464-467.

Rimrott FPJ, Luke JR (1961). Large strain creep of

rotating cylinders. ZAMM-Zeitschrift fur

Angewandte Mathematik und Mechanik, 41:

485-500.

Weir CD (1957). The creep of thick walled tube under

internal pressure. Journal of Applied

Mechanics, 24: 464-466.

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Journal of Solids and Structures, 37: 7593-

7608.



237

Mohammad Zamani Nejad is currently as an assistant professor at the department of Mechanical

Engineering in Yasouj University, Yasouj, Iran. He received his bachelor’s degree in Mechanical

Engineering-Solids Design in Shiraz University and his master’s degree in Mechanical Engineering-

Applied Design in Mazandaran University. He obtained his Ph.D. from Tarbiat Modares University,

Tehran, Iran. His research interests include thermo-elasto plastic analysis and creep analysis of solids.

Mosayeb Davoudi Kashkoli received his bachelor’s degree in Mechanical Engineering-Solids Design in

Yasouj University, Yasouj, Iran. He is currently a graduate student in Mechanical Engineering-Applied

Design in Yasouj University. In his master course, he conducted many researches under the supervision of

Dr. Zamani Nejad. His research interests is creep stress analysis in axisymmetric thick shells.

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