experiences with cutter suction dredge ......cutter suction dredge alaska (courtesy of great lakes...
TRANSCRIPT
EXPERIENCES WITH CUTTER SUCTION DREDGE SIMULATOR TRAINING
R. E. Randall1, P. S. deJong2 and S. A. Miedema3
ABSTRACT
The cutter suction dredge is the most commonly used dredging equipment for dredging navigable waterways. The capital costs of these dredges are in the millions of US dollars and the dredging projects involve the removal of hundreds of thousand to just over a million cubic yards of dredged sediments. Production engineers usually accomplish estimating the production of dredges, and controlling the operation of the dredge is usually the responsibility of the dredge operator (leverman). In order to improve the performance and education of the production engineer and the leverman, cutter suction dredge simulators are available for training of these dredging personnel. Two dredge simulator short courses have been conduct since 1999 and the experience gained from these courses shows that they are valuable training tools. The simulators consist of dredging controls and instrumentation interfaced with a personal computer. Software has been developed that accurately models or simulates the dredge movement, the hydraulic transport, and the cutting of the sediments. Results of the dredge simulation exercise are recorded and used to critique the simulator exercise in order to demonstrate dredging fundamentals such as effects of cavitation, critical velocity, winch power, pump power, and maneuvering of the dredge. Short course participants indicate the simulator is realistic and that it is valuable for training new operators and production engineers. Keywords: Dredge simulator, dredge training, cutter suction dredge, dredge training experience.
INTRODUCTION The hydraulic cutter suction dredge is the most commonly used equipment for excavating and maintaining navigable waterways. The dredge size is defined by the diameter of the discharge line and range in size from 0.15 to 1.22 m (6 to 48 in). The most common size for a cutter suction dredge is 0.61 m (24 in). Small hydraulic cutter suction dredges are considered to range from 0.15 to 0.30 m (6 to 12 in). In the United States the cutter suction dredges accounted for 149.1 million cubic yards of the total 271.2 million cubic yards of the dredging volume during the fiscal years 1996-98.
Pipeline
Spud
cutter
Ladder & Ladder Pump
Figure 1. Cutter suction dredge Alaska (Courtesy of Great Lakes Dredge & Dock).
1 Director, Center for Dredging Studies, Ocean Engineering Program, Civil Engineering Department, Texas A&M University, College Station, Texas, 77843-3136, 979-845-4568, [email protected]. 2 Consultant, Digital Automation and Control Systems, Inc., P. O. Box 925456, Houston, Texas, 77292. 3 Professor, Faculty of Mechanical Engineering and Marine Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft, The Netherlands.
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
The cutter suction dredge consists of a large barge shape vessel that normally doesn’t have propulsion equipment and is mobilized to the job site by other vessels. It has centrifugal pumps on board that are used to pump slurry (mixture of solids and water) to a disposal location. The dredge has a ladder that supports the cutter and cutter drive unit and the suction line leading to the suction side of the dredge pump. At the end of the suction line and cutter drive shaft is the cutterhead that is used to loosen and cut sediment that must be removed from the bottom of the waterway. The cutter may have special teeth for excavating the bottom. The excavated material is mixed with the surrounding water and drawn up the suction pipeline due to the low pressure created by the pump on the suction side. The dredged material may consist of clay, silts, sands and gravel and the slurry may be as much as 20% sediments by volume and the other 80% is the ambient fluid. In some cases, an additional pump may be located on the ladder when dredging depth is deep (greater than 9.1 m or 30 ft) in order improve production due to cavitation limitations. On the discharge side of the main dredge pump, a long pipeline is used to transport the slurry to the disposal location that is typically a confined disposal site. The length of the pipeline may be as long as several miles. The power available and head developed by the pump or pumps must be enough to overcome the hydraulic friction losses occurring in the total pump and pipeline system. Additionally, the velocity in the pipeline on the suction and discharge side must be above the critical velocity required to suspend the sediments in the carrier fluid. This critical velocity depends primarily on sediment grain size, sediment specific gravity, and pipeline diameter. Additional pumps (called booster pumps) are sometimes needed to transport the dredged material through very long pipelines. The dredged material lay on the bottom of the waterway and therefore, the dredge must move along the waterway (channel) to excavate the sediments. The dredge typically uses spuds, winches and anchors to move it. Spuds are large vertical cylinders that are located at the stern of the dredge. Hydraulic cutter suction dredges use two spuds arranged at a specified separation distance at the stern or with one at the stern and one in a carriage arrangement. Advancing the dredge is accomplished by alternately raising and lowering the two spuds at the appropriate positions and consequently the dredge walks up the channel or is advanced by the spud carriage. Winches and wires on the port and starboard side of the dredge are used to swing the dredge back and forth across the channel bottom to bring the cutter in contact with the sediment that is to be removed. The swinging of the dredge is about the one spud that is driven into the sediment. The two spud walking dredge arrangement has a production efficiency of approximately 50 %, which means the dredge is removing sediment only half of the time. Dredges with the spud carriage arrangement are more efficient and usually can be removing sediment 75 % of the time. The winches must have enough power to move the cutter across the channel and the wires must be strong enough to prevent breaking and costly downtime for the dredge. The winch wires are normally attached to anchors placed in the channel and these must be moved as the dredge moves up the channel. The operation of a cutter suction dredge just described is complicated and requires skilled dredge operators. These skilled operators (levermen) are essential for a successful and profitable dredging operation. In many cases, these skills are attained through on the job training and over many years under the tutelage of an experienced operator. The operator is assisted by crew who must move anchors, operate engines and pumps, and monitor pipelines. The dredging projects cost millions of dollars and the cutter suction dredge capital costs are in the millions of dollars. Consequently, it is prudent for dredging companies to invest in training their operators so that they have the best understanding of the hydraulic transport and dredge maneuvering principles. Recently, Digital Automation and Control Systems (DACS 1994) and others (Cox et al 1995) have developed dredging simulators for the purpose of training dredge operators. Simulators have been used for a long time to train ship pilots and airplane pilots. The investment in dredge simulator training is expected to improve dredging efficiency and maximize profits for the dredging company and also reduce the costs of dredging projects. Miedema (1999) discussed the principles of developing dredge simulators that interface dredge controls with a personal computer that is the platform for a sophisticated hydraulic simulation of the entire dredging process including transport, cutting, and advancing the dredge. The objective of this paper is to discuss the experiences obtained in two training courses sponsored by the Center for Dredging Studies and the Digital Automation and Control Systems (DACS). These courses were presented over a 1-½ day period in 1999 and a 2-½ day period in January 2000.
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
DESCRIPTION OF SIMULATORS
The cutter suction dredge simulator consists of two control consoles interfaced to a personal computer. The first DACS simulator used a 486/66 MHz personal computer using Windows 3.1. In 1999, the simulator was upgraded to Pentium II/133 MHz computer running in Windows 95. The software simulating the dredging operations is written in Visual Basic. Figure 2 shows the two simulators that were used during the January 2000 cutter suction dredge short course. The simulator on the left was borrowed from Great Lakes Dredge and Dock and the other simulator is the DACS system.
Great Lakes Dredge &Dock DACS/TAMU
Figure 2. Photograph of the cutter suction dredge simulators.
The simulator incorporates accepted hydraulic transport theories (Durand, 1953 or Wilson, 1997) and combines them with empirical data and a model for soil cutting (Miedema, 1995 & 1996). The user has the capability of specifying:
• Channel geometry • Geotechnical data (grain size, sand/clay, etc.) • Pipeline length and diameter • Pumping power and pump curves • Cutter drive and winch drive • Dredge geometry
The simulator is designed to show operators and production engineers how to improve their skills and dredge performance through the use of instrumentation. All dredging processes including dredge motions (swing and advance), cutting process and slurry transport are simulated. The user can experiment with improving productivity without worrying about the consequences of plugging the line and suffering costly downtime. Using the simulator to replicate the dredging process, the operator can learn to achieve maximum production. In fact the actual dredge characteristics for the dredge that the operator is normally operating can be input. The large computer screen shows a panel of gauges, a top view of the channel and dredge with swing wires, and a window that can be toggled between a side and rear view of the dredge. Pertinent information such as swing rate, production rate, total production, cutter depth, spud carrier position, and swing angle are illustrated at the bottom of the window. Error messages and time of dredging are shown at the bottom line of the window. The panel of gauges includes pump speed, pump power, cutter speed, cutter power, slurry specific gravity, slurry velocity, suction pressure, discharge pressure, port winch force, and starboard winch force.
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
Figure 3. Display on computer screen during simulator operations.
The dredging simulator uses input files to define the characteristics of the dredge, channel, and sediments. These file names are:
• Channel • Friction • Pontoon • Clay • Gauges • Sand • Console • Ladder • Spud • Current • Pipeline • Wire • Cutter • Main pump
These files can be changed to specify a particular dredge and project specific condition. For example the characteristics of the dredge pump and performance curves can be input. The pipeline characteristics and fittings are defined in the pipeline file. An example of portions of the pipeline, channel and main pump input files are tabulated in Table 1. A very useful capability of the simulator software is its ability to capture data during each simulator exercise, and these data are plotted to show the participant the result of all the data and actions during the exercise. An example of the output for production is illustrated in Figure 4 that shows slurry density, slurry velocity, swing speed, and production as a function of time and a data point is recorded for every time step in the simulation. The solid line in Figure 4 represents the average value of the recorded data over the exercise time period. The units SI or US presented are specified at the start of the simulation when it is started.
4
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
Table 1. Selected Portions of Simulator Input File (channel, pipeline, main pump).
Channel Pipeline Main Pump Total width of top view and front view (m) - 150
Theory Used: 0 – Durand, 1 – Wilson fine, 3 – Wilson coarse - 0
Power (kW) - 835
Water level of new channel (m) - 13 Pipe Section 0 Suction Impeller diameter (m) – 1.35 Width of old channel (m) – 100 Pipe diameter (m) - 0.4 Revolutions (rpm) – 450 Depth of old channel (m ) – 10 Pipe length (m) - 26 Maximum Revolutions (rpm) – 500 Slope of old channel (m) – 30 Pipe roughness – 0.0001 Data Points for Performance Curve Width of new channel (m) – 130 Pipe fittings Flow m3/s Head kPa Eff NPSH m Depth of New Channel (m) – 15 Number of elbows 0.31 1150 0.55 80 Slope of new channel (m) – 30 Number of swan necks 0.47 1060 0.75 80 Soil type (0=sand, 1=clay) - 0 Pipe Section 1 0.63 980 0.85 78 Pipe diameter – 0.4 0.79 790 0.87 76
00:00 00:02 00:04 00:06 00:08 00:10 00:12 00:14 00:16 00:18 00:201.0
1.2
1.4
1.6
1.8
2.0Slurry density vs time
Time
s.g.
00:00 00:02 00:04 00:06 00:08 00:10 00:12 00:14 00:16 00:18 00:200.0
6.0
12.0
18.0
24.0
30.0Slurry velocity vs time
Time
ft/s
00:00 00:02 00:04 00:06 00:08 00:10 00:12 00:14 00:16 00:18 00:20-200
-120
-40
40
120
200Swing speed vs time
Time
ft/m
in
00:00 00:02 00:04 00:06 00:08 00:10 00:12 00:14 00:16 00:18 00:200
2400
4800
7200
9600
12000Production rate vs time
Time
cy/h
r
Figure 4. Example plots from simulator showing the data gathered by the simulator.
The actions of the participant using the simulator and error messages are recorded along with the time of the action or message (Table 2). Actions recorded include lowering the ladder, starting pumps, raising and lowering spuds,
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
etc., and error messages such as main pump cavitating, cutter clogged, deposit in the pipeline, pipeline clogged, and no spud on the ground are disp
2. A partial record of simulator user actions.
layed.
Table
Date : 01-05-2000 Time : 14:57:37 Student : Name Company : Name
.94 ft
0:04:44 Action! Ladder hoisted 0:04:45 Action! Swing to port
ID : Student #1 Sessions: 1 0:00:00 Action! Start of session 0:00:00 Action! Start of simulation 0:00:00 Action! Cutter drive enabled 0:00:00 Message! Suction mouth above water, stop cutter drive 0:00:05 Action! Main pump enabled 0:00:05 Error! Suction mouth above water, stop main pump 0:00:25 Action! Starboard winch in dual operation 0:00:35 Message! Screen console input 0:00:37 Action! Starboard winch in single operation 0:00:37 Error! Suction mouth above water, stop main pump 0:00:48 Action! Port anchor moved by mouse X = 288.40 ft - Y = 135.27 ft 0:00:48 Error! Suction mouth above water, stop main pump 0:00:58 Action! Starboard anchor moved by mouse X = 30.13 ft - Y = 1370:01:18 Action! Starboard winch in dual operation 0:01:27 Error! Suction mouth above water, stop main pump 0:01:33 Action! Ladder lowered 0:01:33 Fatal error! Pipeline clogged 0:01:54 Action! Ladder hoisted 0:01:59 Action! Swing to starboard 0:02:10 Action! Ladder lowered 0:02:11 Action! Swing to starboard 0:02:19 Action! Swing to port 0:02:21 Action! Swing to port 0:02:35 Action! Free fall of the step spud 0:02:40 Action! Step spud lowered 0:02:40 Action! Work spud hoisted 0:02:43 Action! Swing to port 0:03:03 Error! Main pump cavitating, raise ladder 0:03:14 Action! Swing to port 0:03:21 Error! Main pump cavitating, raise ladder 0:03:25 Action! Swing to starboard 0:03:32 Action! Work spud lowered 0:03:33 Action! Free fall of the work spud 0:03:34 Action! Step spud hoisted 0:03:42 Action! Swing to port 0:04:00 Error! Main pump cavitating, raise ladder 0:04:01 Error! Main pump cavitating, raise ladder 0:04:07 Error! Main pump cavitating, raise ladder 0:04:17 Action! Swing to port 0:04:29 Error! Main pump cavitating, raise ladder 0:04:35 Warning! Cutter clogged
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
COURSE ORGANIZATION Several years ago (1995) the DACS cutter suction dredge simulator was placed at the Center for Dredging Studies at Texas A&M University, and a set of simulator exercises were developed by the Center with the intention of providing a training course for dredge operators and production engineers. In addition to the simulator exercises, relatively short presentations are given on fundamental dredge hydraulics, the sediment cutting process and a demonstration of the dredge simulator as shown in Table 3. The first course was presented in January 1999 using one simulator and experienced operators and production engineers were asked to participate to determine the utility
f the simulator. The 1 1/2-day course was successful and the participants recommended that the course length be
lained. Exercise 7 had no limitations such as cavitation, long pipeline, power to e pump or cutter, or winch limitations, so the participants could become accustom to the simulator, control console
and instrumentation information.
T chedule for 2 1/2 Day Short Course
oextended and offered as training for young operators and production engineers. The second offering of the cutter suction dredge simulator short course was presented January 6-8, 2000. A course fee of $1200 was established to offset some of the course costs. The agenda for this short course is tabulated in Table 3. Eight participants arrive the evening before the first day and the cutter suction dredge simulator training manual (Randall and Albar, 1999) was given to the participants. The first day of the 2 1/2-day course consisted of presentations on dredge hydraulics and cutting of the bottom sediments and a demonstration of the two simulators. In the afternoon, all participants were given the opportunity to operate the simulator using simulator exercise number 7, which was a large spud carriage cutter suction dredge 0.76 m (30 in). Each participant was given 45 minutes to complete exercise 7. After all the participants completed the exercise, the data recorded for each participant was reviewed and expth
able 3. STime Topic First Day 8:00 - 8:30 Introduction 8:30 - 9:15 Dredge Hydraulics 9:15 - 10:00 Cutting of Bottom Sediments 10:00 - 10:30 Refreshment Break 10:30 - 10:45 Simulator Description & Operating Training Manual Review 10:45 - 11:30 Simulator Demonstration 11:30 - 12:30 Lunch 12:30 - 1:15 Simulator Exercise 7 for Participants 1 and 2 1:15 - 2:00 Simulator Exercise 7 for Participants 3 and 4 2:00 - 2:30 Refreshment Break 2:30 - 3:15 Simulator Exercise 7 for Participants 5 and 6 3:15 - 4:00 cise 7 for Participants 7 and 8 Simulator Exer4:00 - 5:00 Review Simulator Exercise 7 Results 5:00 Adjourn Second Day 8:00 - 8:15 Introduction to Day 2 Activities 8:15 - 9:15 Simulator Exercise 4, 5, & 6 for Participants 1 and 2 9:15 - 10:15 Simulator Exercise 4, 5, & 6 for Participants 3 and 4 10:15 - 10:30 Refreshment Break 10:30 - 11:30 Simulator Exercises 4, 5, & 6 for Participants 5 and 6 11:30 - 12:30 d 8 Simulator Exercises 4, 5, & 6 for Participants 7 an12:30 - 1:30 Lunch 1:30 - 2:30 Review Simulator Exercises 4, 5 & 6 Results 2:30 - 3:30 Simulator Exercises 3 & 1 for Participants 1 and 2 3:30 - 4:00 eak Refreshment Br4:00 - 5:00 Simulator Exercises 3 & 1 for Participants 3 and 4 5:00 Adjourn Third Day 8:00 - 8:15 Introduction to Day 3 Activities 8:15 - 9:15 Simulator Exercises 3 &1 for Participants 5 & 6 9:15 - 10:15 Simulator Exercises 3 & 1 for Participants 7 and 8 10:15 -10:30 Refreshment Break 10:30 - 11:30 ercise 3 & 1 Results Review Simulator Ex11:30 - 12:00 Short Course Critique & Certificate/CEU Presentations 12:00 Course Completion
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
On the second day, the exercises were for a 0.4 m (16 in) cutter suction dredge. Exercise 6 did not have any limitations so again the participants should be able to maximize the production for this simulated dredge. Exercise 5 had a 5000 m (16,400 ft) pipeline and this was to challenge the participants in controlling the slurry density and velocity within the limits of the pump to maintain production without plugging the pipeline. Participants were expected to have trouble maintaining the same production as achieved in exercise 6. In Exercise 4, the pump and winch power was reduced to demonstrate the effect on production. A review of the data recorded was again resented at the conclusion of these exercises for all participants.
mm) and the parameters of water depth, cutter size, channel width, and spud separation mained constant.
SIMULATOR EXERCISES
uds. EXAM7 is a 0.75 m (30 in) dredge with a spud carriage. These exercise dredges are briefly described below:
•
l suction pipe, this dredge will demonstrate cavitation readily at high slurry velocities and densities.
•
itation. However, production may still be limited in this scenario by deposition in the discharge line.
possible to operate at higher densities, but it may still be limited by deposition in the discharge line.
n will definitely be apparent in this scenario and will demonstrate the need for a more powerful pump.
f this dredge are the same as TEXAM4, and the only limit on production is the power of the winches.
ise similar to TEXAM5, and an increase in production will be apparent due to the stronger winches.
he discharge pipe diameter is 0.75 m (30 in). The discharge pipeline length is 5000 m (16,400 ft).
p Exercises 3 and 1 were started for four of the participants in the afternoon of the second day and completed by the remaining four students at the beginning of the last day, which was to be a half day. The pipeline length was reduced to 2000 m (6,560 ft), but otherwise it was the same as exercise 4. For exercise 1, the ladder pump was removed and the suction limitation (cavitation) was demonstrated. It was expected that the participants would experience a reduced production compared to Exercise 3. For all the Texas A&M exercises 1-6, the sand material was the same (d50=0.5re
There are seven built-in scenarios on exercises provided with the simulator software. The exercises are called TEXAM1 through TEXAM7. The TEXAM1 through 6 are a 0.4 m (16 in) cutter suction dredge with fixed spT
TEXAM1 – This dredge has no ladder pump, only an inboard pump, and the discharge pipeline is 2000 m (6560 ft) in length. Both the suction and discharge pipes are 0.4 m (16 in) in diameter. Due to the relatively smal
TEXAM2 – The cavitation problem is removed in this scenario by increasing the suction pipe diameter to 0. 5 m (20 in). In all other respects this is the same dredge as TEXAM1. This scenario is intended to demonstrate that greater production can be achieved by increasing the suction pipe diameter and thereby removing the suction lim
• TEXAM3 – This is the same dredge as TEXAM1, but with a ladder pump installed. This scenario will
demonstrate the improvement in production for a dredge when a ladder pump is added, all else being the same. With this dredge it is
• TEXAM4 – This dredge is the same as TEXAM3, but with a discharge pipeline of 5000 m (16,400 ft)
in length. The discharge limitatio
• TEXAM5 – The deposition problem is addressed in this scenario by replacing the pump in scenario
four with a much more powerful one. All other aspects o
• TEXAM6 – More powerful winches are added in this scenario, and the discharge pipeline is shortened
back to 2000 m (6560 ft). It is otherw
• TEXAM7 – This is a spud carriage dredge with almost no limits. The operator will be able to learn the
spud carriage operation and become familiar with the dredge simulator. The suction pipe diameter is 0.81m (32 in) and t
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
Exercises TEXAM1 through TEXAM6 uses these common parameters:
15 ft/s)
• More details regarding the dredge for scenario TEXAM1 through TEXAM6 are presented in Figure 3.
cenario TEXAM7 uses these parameters:
tion window • More details regarding the dredge for scenario TEXAM7 are presented in Figure 4.
tion engineer hould have a basic understanding of these factors and should be ready to train for a specific project.
RESULTS OF EXERCISES
ump or plugging the pipeline. Six of the participants plugged e pipeline after about 25 minutes on the simulator.
lugged. This exercise also provides the articipants the opportunity to experience working with a spud carriage.
ng speed, production, cutter depth, ing angle, distance from the center of the channel and time were also shown.
• Channel water depth = 17 m (55.1 ft) • Soil is medium sand (d50= 0.5mm, d15 = 0.25mm, d85 = 0.75mm) • Critical Velocity for 0.4 m (16 in) discharge pipe = 4.6 m/s (• Advance Angle (sin θ = 1.1/6 = 0.18333, θ = 10.6 degrees) • More details data using in each scenario can be seen by clicking EDIT in the Simulation window
S
• Channel water depth = 8 m (26.2 ft) • Soil is medium sand (d50= 0.5mm, d15 = 0.25mm, d85 = 0.75mm) • Critical Velocity for 0.75 m (30 in) discharge pipe = 6.5 m/s (21.3 ft/s) • More details data using in each scenario can be seen by clicking EDIT in the Simula
These basic exercises are intended to demonstrate the effects of slurry velocity, slurry density, and dredge characteristics on production. After completing the lessons provided, a dredge operator or producs
Seven exercises are available on the simulator, but only six of these were used in the January 2000 short course. Exercise number 7 is a large 0.75 m (30 in) cutter suction dredge that has a spud carriage and is equipped with a ladder pump. The main pump power and the winch power are more than adequate and the pipeline length is 5000 m (16,400 ft). The suction pipe is 0.81 m (32 in). It is believed that a large dredge with essentially no dredging limitations was the best for the participants to start there training and acclimate themselves to the simulator and the controls on the console. Since there were two simulators the class was divided in half and each participant completed all their exercises on the same simulator so they didn't have to readjust for different exercises. The software is identical on the two simulators, but the control consoles are different. The channel sediment is sand with a d50 of 0.5 mm and the channel water depth and width are 8 m (26.2 ft) and 100 m (328 ft), respectively. The cutter base diameter is 2 m (6.3 ft). All the participants were given about 45 minutes on the simulator with instruction to try to maximize the production without cavitating the pth An example of the production data curves is illustrated for one of the participants in Figure 5. The results show the slurry velocity beginning to drop after 12 minutes into the exercise and at about 19 minutes the sediment began to settle in the pipe. Figure 5 shows the average specific gravity being pumped is about 1.15 and the average velocity is 14 ft/s. For sand with a d50 of 0.5 mm, the critical velocity for deposit in a 0.76 m (30 in) pipeline is approximately 23 ft/s. The velocity shown in Figure 5 is well below the critical velocity and consequently the sediment settled in the pipe, eventually plugging the pipe. This is evident when the velocity went to zero at about 20 minutes and the program gave a fatal error that the pipeline was pp Two simulators are operating simultaneously during the training and the computer screen from each simulator is projected on a screen so that everyone can observe the ongoing dredging. This information is useful to the instructors observing the participants and for the inactive participants to learn from those on the simulators. Figure 5 illustrates the information shown on the screen that included gauge readings, plan view of the dredge and channel, and a stern or side view of the dredge and channel. The operator could clearly see the location of the cutter and a green line marked the area that had been dredged. Information showing swisw
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
00:00 00:03 00:06 00:09 00:12 00:15 00:18 00:21 00:24 00:27 00:301.0
1.2
1.4
1.6
1.8
2.0Slurry density vs time
Time
s.g
.
00:00 00:03 00:06 00:09 00:12 00:15 00:18 00:21 00:24 00:27 00:300.0
6.0
12.0
18.0
24.0
30.0Slurry velocity vs time
Time
ft/s
00:00 00:03 00:06 00:09 00:12 00:15 00:18 00:21 00:24 00:27 00:30-200
-120
-40
40
120
200Swing speed vs time
Time
ft/m
in
00:00 00:03 00:06 00:09 00:12 00:15 00:18 00:21 00:24 00:27 00:300
2400
4800
7200
9600
12000Production rate vs time
Time
cy/h
r
Figure 5. Production data curves showing slurry density, slurry velocity, swing speed, and total production
using exercise 7.
Once the participants are acclimated to the simulator, they are introduced to a smaller cutter suction dredge that has five exercises. The five exercises, which are numbered 1, 3, 4, 5, and 6, are compared in Table 4. The purpose of the different exercises is to expose the participants to increasingly more difficult conditions for dredging and to demonstrate hydraulic principles of available power, long pipelines, critical velocity, and cavitation limitations. It is intended to demonstrate the effects of these hydraulic limitations (cavitation, power for pump, power for winch, power for cutter, and critical velocity) on the production.
Table 4. Comparison of Cutter Suction Dredge Simulator Exercises Used in January 2000 Short Course
Characteristic Exercise 1 Exercise 3 Exercise 4 Exercise 5 Exercise 6 Suction Pipe 0.4 m (16 in) 0.4 m (16 in) 0.4 m (16 in) 0.4 m (16 in) 0.4 m (16 in) Discharge Pipe 0.4 m (16 in) 0.4 m (16 in) 0.4 m (16 in) 0.4 m (16 in) 0.4 m (16 in) Ladder Pump No Yes Yes Yes Yes Main Pump Power Low Low Low Maximum Maximum Winch Power Low Low Low Low Maximum Pipeline Length 2000 m
(6560 ft) 2000 m (6560 ft)
5000 m (16400 ft)
5000 m (16400 ft)
2000 m (6560 ft)
Common Characteristics Sand grain size d50 =0.5 mm Water depth 16.8 m (55 ft) Cutter size 1.2 m base
1.1 m height 1.0 m top
Channel Width 84 m (276 ft) Spud Separation 6 m (19.7 ft)
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
Figure 6 shows a summary of the production in cubic yards/hr for eight participants while conducting the five exercises. As illustrated in Figure 6, participants 1, 4, 7 and 8 attained the best production over all the exercises. Exercise 6 was meant to have high production because there was maximum power, short pipeline, and a ladder pump. However, when the participants move to exercise 5, the production for most participants increased even though the pipeline increased from 2000 m to 5000 m (6560 to 16400 ft). In exercise 4, the power for the main pump was reduced and for most of the participants showed a decrease in the production. Exercise 3 has the same power as exercise 4, but the pipeline length was reduced to 2000 m (6560 ft). Seven out of the eight participants increased the production and this is attributed to the decreased line length. Exercise 1 removed the ladder pump and everything else remained the same as exercise 3. The effect of cavitation was clearly evident and resulted in the production by all the participants being reduced by 50 % or more. These results show the simulator exercises demonstrate the limitations on production caused by cavitating pumps, increase line length, and power to the pump. Winch and cutter power are also limitations, but new exercises need to be generated to demonstrate these limitations more clearly.
0
100
200
300
400
500
600
700
800
900
1000
1100
0 1 2 3 4 5 6 7 8 9
Participant
Prod
uctio
n (c
y/hr
)
Ex 1Ex 3Ex 4Ex 5Ex 6
Figure 6. Comparison of production for each participant for the different exercises.
Exercises number 3 and 1 illustrated the effects of cavitation on dredge production. In exercise 3 the cutter suction dredge had a ladder pump and the short line (2000m, 6560 ft). The critical velocity for a 0.4 m (16 in) line transporting material with a d50 of 0.5 mm is approximately 15 ft/s. The data collected for exercise 3 (Figure 7) shows an average slurry density 1.2 with maximum specific gravity as high as 1.6. The average slurry velocity was 20 ft/s and the maximum swing velocity was 120 ft/min. During this exercise the average production is about 1000 cy/hr. The main pump suction pressure fluctuates between 30 in of Hg and -30 in Hg, which indicates the operator was attempting to dredge as high a specific gravity as possible regardless of the occasional main pump cavitating message. As a result, the production was maximized. The average slurry velocity during the exercise was approximately 19 ft/s, which is about 4 ft/s above the critical velocity.
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
00:00 00:03 00:06 00:09 00:12 00:15 00:18 00:21 00:24 00:27 00:301.0
1.2
1.4
1.6
1.8
2.0Slurry density vs time
Time
s.g.
00:00 00:03 00:06 00:09 00:12 00:15 00:18 00:21 00:24 00:27 00:300.0
8.0
16.0
24.0
32.0
40.0Slurry velocity vs time
Time
ft/s
00:00 00:03 00:06 00:09 00:12 00:15 00:18 00:21 00:24 00:27 00:30-200
-120
-40
40
120
200Swing speed vs time
Time
ft/m
in
00:00 00:03 00:06 00:09 00:12 00:15 00:18 00:21 00:24 00:27 00:300
2400
4800
7200
9600
12000Production rate vs time
Time
cy/h
r
Time
00:00 00:03 00:06 00:09 00:12 00:15 00:18 00:21 00:24 00:27 00:30-30
-18
-6
6
18
30Main pump vacuum vs time (-=vacuum, +=pressure)
Time
inch
Hg
00:00 00:03 00:06 00:09 00:12 00:15 00:18 00:21 00:24 00:27 00:300
60
120
180
240
300Main pump discharge pressure vs time
Time
psi
Figure 7. Example exercise 3 production and main pump data using ladder pump and short pipeline.
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
In exercise 1, the ladder pump is removed and the operator tries to maximize the production. As shown in Figure 8 the operator is able to average a 1.2 specific gravity with peaks up to 1.8 specific gravity. The slurry velocity drops to an average of 16 ft/s that is just 1 ft/s above the critical velocity. The swing rate is reduced and the production is reduced to about 500 cy/hr that is a drop of one half. The main pump suction pressure is always negative and ranges between -6 and -30 in of Hg. The operator essentially is cavitating the pump through out the exercise as evidenced by the number of times the suction pressure approached and passed -30 in of Hg. A review of the error messages indicated that 65 main pump cavitating messages were received. Production would have reduced more if the operator tried to avoid cavitation by reducing the average specific gravity. These two exercises clearly show the benefit of the ladder pump in maximizing production and reducing wear and tear on the main pump due to excessive cavitation.
SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS Two cutter suction dredge simulator short courses were conducted in 1999 and 2000. Five participants attended the first 1 1/2 day course and eight attended the second 2 1/2 day course. In the second course, two dredge simulators were used. In order to increase the time on the simulators, the number of simulators must be increased or the length of the course must be extended. The use of the computer projection equipment to display the simulator actions is very helpful to the participants not on a machine, and it encourages discussion among all the participants, which was an unanticipated benefit. The simulator is a very realistic model for cutter suction dredges and has proven to be a reliable simulation of actual cutter suction dredging operations. Participants in two cutter suction dredge simulator short courses indicate that training on the simulator would benefit dredge leverman and production engineers. The seven exercises that have been developed demonstrate hydraulic transport principles. The effect of winch and main pump power limits, length of pipeline, and ladder pump are demonstrated. Participants need time to adjust to the control and computer set-up. Most participants indicate they would like more time on the exercises and perhaps be able to repeat the exercises to improve their performance. The first two short courses did not attempt to change the sediment or incorporate environmental conditions such as channel currents, or change channel geometry conditions. All of this could be accomplished, but it would increase the length of the course or require the addition of another simulator. Participants indicated they would like to try the different sediment conditions. The critiques after each exercise are useful in showing each participant the results of their actions. The ability to capture the data and display it for the participant is considered valuable by the participants. The presentations on fundamentals of slurry transport and cutting of soils proved to be useful to the operators and production engineers. The participants recommend question and answer sessions. Most of the operators do not have a formal engineering education and the opportunity to have slurry transport fundamentals explained seemed to be well received. Explanations in lay terms was emphasized instead of engineering theories. Critiques by the participants at the close of the short course indicated the course was well received. The length of the course was considered to be about right with a possible extension of one day for additional dredging conditions. Additional discussion on cutters and booster pumps was suggested. The simulator with the Windows 3.1 needed to be upgraded to Windows 95, and a faster computer with more memory will improve the handling of data.
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
00:00 00:03 00:06 00:09 00:12 00:15 00:18 00:21 00:24 00:27 00:301.0
1.2
1.4
1.6
1.8
2.0Slurry density vs time
Time
s.g.
00:00 00:03 00:06 00:09 00:12 00:15 00:18 00:21 00:24 00:27 00:300.0
8.0
16.0
24.0
32.0
40.0Slurry velocity vs time
Time
ft/s
00:00 00:03 00:06 00:09 00:12 00:15 00:18 00:21 00:24 00:27 00:30-200
-120
-40
40
120
200Swing speed vs time
Time
ft/m
in
00:00 00:03 00:06 00:09 00:12 00:15 00:18 00:21 00:24 00:27 00:300
2400
4800
7200
9600
12000Production rate vs time
Time
cy/h
r
Time
00:00 00:03 00:06 00:09 00:12 00:15 00:18 00:21 00:24 00:27 00:30-30
-18
-6
6
18
30Main pump vacuum vs time (-=vacuum, +=pressure)
Time
inch
Hg
00:00 00:03 00:06 00:09 00:12 00:15 00:18 00:21 00:24 00:27 00:300
60
120
180
240
300Main pump discharge pressure vs time
Time
psi
Figure 8. Example exercise 1 production and main pump data showing effects of cavitation.
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
15
REFERENCES Cox, C. M., Eygenraam, J. A., Granneman, C. C. O. N., and Njoo, M., “A Training Simulator for Cutter Suction
Dredgers: Bridging the Gap between Theory and Practice,” Proceedings of World Dredging Congress, WODCON XIV, Amsterdam, The Netherlands, November, 1995.
Digital Automation and Control Systems (DACS), “Hydraulic Dredging Simulator,” Houston, Texas, 1994. Durand, R., “Basic Relationship of the Transportation of Solids in Pipes – Experimental Research,” Proceedings of
the International Association for Hydraulic Research, University of Minnesota, 1953. Miedema, S. A. “Considerations in Building and using Dredge Simulators,” Proceedings of the Western Dredging
Association XIX Technical Conference and 31st Texas A&M Dredging Seminar, Louisville, KY, Center for Dredging Studies, Texas A&M University, College Station, TX, May 15-18, 1999.
Miedema, S. A. “Modeling and Simulation of the Dynamic Behavior of a Pump/Pipeline System,” Proceedings of the WEDA Technical Conference and Texas A&M Dredging Seminar, New Orleans, June 1996.
Miedema, S. A., “Production Estimation Based on Cutting Theories for Cutting Water Saturated Sand,” Proceedings of World Dredging Congress, WODCON XIV, Amsterdam, The Netherlands, November, 1995.
Randall, R. E. and Albar, A. “Cutter Suction Dredge Simulator Training Manual, Center for Dredging Studies, Ocean Engineering Program, Civil Engineering Department, Texas A&M University, College Station, Texas, January 2000.
Wilson, K. C., Addie, G. R., Sellgren, A., and Clift, R., Slurry Transport Using Centrifugal Pumps, Blackie Academic & Professional: New York, Second Edition, 1997.
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
Bibliography Dr.ir. S.A. Miedema 1980-2010
1. Koert, P. & Miedema, S.A., "Report on the field excursion to the USA April 1981" (PDF in Dutch 27.2 MB). Delft University of Technology, 1981, 48 pages.
2. Miedema, S.A., "The flow of dredged slurry in and out hoppers and the settlement process in hoppers" (PDF in Dutch 37 MB). ScO/81/105, Delft University of Technology, 1981, 147 pages.
3. Miedema, S.A., "The soil reaction forces on a crown cutterhead on a swell compensated ladder" (PDF in Dutch 19 MB). LaO/81/97, Delft University of Technology, 1981, 36 pages.
4. Miedema, S.A., "Computer program for the determination of the reaction forces on a cutterhead, resulting from the motions of the cutterhead" (PDF in Dutch 11 MB). Delft Hydraulics, 1981, 82 pages.
5. Miedema, S.A. "The mathematical modeling of the soil reaction forces on a cutterhead and the development of the computer program DREDMO" (PDF in Dutch 25 MB). CO/82/125, Delft University of Technology, 1982, with appendices 600 pages.
6. Miedema, S.A.,"The Interaction between Cutterhead and Soil at Sea" (In Dutch). Proc. Dredging Day November 19th, Delft University of Technology 1982.
7. Miedema, S.A., "A comparison of an underwater centrifugal pump and an ejector pump" (PDF in Dutch 3.2 MB). Delft University of Technology, 1982, 18 pages.
8. Miedema, S.A., "Computer simulation of Dredging Vessels" (In Dutch). De Ingenieur, Dec. 1983. (Kivi/Misset).
9. Koning, J. de, Miedema, S.A., & Zwartbol, A., "Soil/Cutterhead Interaction under Wave Conditions (Adobe Acrobat PDF-File 1 MB)". Proc. WODCON X, Singapore 1983.
10. Miedema, S.A. "Basic design of a swell compensated cutter suction dredge with axial and radial compensation on the cutterhead" (PDF in Dutch 20 MB). CO/82/134, Delft University of Technology, 1983, 64 pages.
11. Miedema, S.A., "Design of a seagoing cutter suction dredge with a swell compensated ladder" (PDF in Dutch 27 MB). IO/83/107, Delft University of Technology, 1983, 51 pages.
12. Miedema, S.A., "Mathematical Modeling of a Seagoing Cutter Suction Dredge" (In Dutch). Published: The Hague, 18-9-1984, KIVI Lectures, Section Under Water Technology.
13. Miedema, S.A., "The Cutting of Densely Compacted Sand under Water (Adobe Acrobat PDF-File 575 kB)". Terra et Aqua No. 28, October 1984 pp. 4-10.
14. Miedema, S.A., "Longitudinal and Transverse Swell Compensation of a Cutter Suction Dredge" (In Dutch). Proc. Dredging Day November 9th 1984, Delft University of Technology 1984.
15. Miedema, S.A., "Compensation of Velocity Variations". Patent application no. 8403418, Hydromeer B.V. Oosterhout, 1984.
16. Miedema, S.A., "Mathematical Modeling of the Cutting of Densely Compacted Sand Under Water". Dredging & Port Construction, July 1985, pp. 22-26.
17. Miedema, S.A., "Derivation of the Differential Equation for Sand Pore Pressures". Dredging & Port Construction, September 1985, pp. 35.
18. Miedema, S.A., "The Application of a Cutting Theory on a Dredging Wheel (Adobe Acrobat 4.0 PDF-File 745 kB)". Proc. WODCON XI, Brighton 1986.
19. Miedema, S.A., "Underwater Soil Cutting: a Study in Continuity". Dredging & Port Construction, June 1986, pp. 47-53.
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
20. Miedema, S.A., "The cutting of water saturated sand, laboratory research" (In Dutch). Delft University of Technology, 1986, 17 pages.
21. Miedema, S.A., "The forces on a trenching wheel, a feasibility study" (In Dutch). Delft, 1986, 57 pages + software.
22. Miedema, S.A., "The translation and restructuring of the computer program DREDMO from ALGOL to FORTRAN" (In Dutch). Delft Hydraulics, 1986, 150 pages + software.
23. Miedema, S.A., "Calculation of the Cutting Forces when Cutting Water Saturated Sand (Adobe Acrobat 4.0 PDF-File 16 MB)". Basic Theory and Applications for 3-D Blade Movements and Periodically Varying Velocities for, in Dredging Commonly used Excavating Means. Ph.D. Thesis, Delft University of Technology, September 15th 1987.
24. Bakker, A. & Miedema, S.A., "The Specific Energy of the Dredging Process of a Grab Dredge". Delft University of Technology, 1988, 30 pages.
25. Miedema, S.A., "On the Cutting Forces in Saturated Sand of a Seagoing Cutter Suction Dredge (Adobe Acrobat 4.0 PDF-File 1.5 MB)". Proc. WODCON XII, Orlando, Florida, USA, April 1989. This paper was given the IADC Award for the best technical paper on the subject of dredging in 1989.
26. Miedema, S.A., "The development of equipment for the determination of the wear on pick-points" (In Dutch). Delft University of Technology, 1990, 30 pages (90.3.GV.2749, BAGT 462).
27. Miedema, S.A., "Excavating Bulk Materials" (In Dutch). Syllabus PATO course, 1989 & 1991, PATO The Hague, The Netherlands.
28. Miedema, S.A., "On the Cutting Forces in Saturated Sand of a Seagoing Cutter Suction Dredge (Adobe Acrobat 4.0 PDF-File 1.5 MB)". Terra et Aqua No. 41, December 1989, Elseviers Scientific Publishers.
29. Miedema, S.A., "New Developments of Cutting Theories with respect to Dredging, the Cutting of Clay (Adobe Acrobat 4.0 PDF-File 640 kB)". Proc. WODCON XIII, Bombay, India, 1992.
30. Davids, S.W. & Koning, J. de & Miedema, S.A. & Rosenbrand, W.F., "Encapsulation: A New Method for the Disposal of Contaminated Sediment, a Feasibility Study (Adobe Acrobat 4.0 PDF-File 3MB)". Proc. WODCON XIII, Bombay, India, 1992.
31. Miedema, S.A. & Journee, J.M.J. & Schuurmans, S., "On the Motions of a Seagoing Cutter Dredge, a Study in Continuity (Adobe Acrobat 4.0 PDF-File 396 kB)". Proc. WODCON XIII, Bombay, India, 1992.
32. Becker, S. & Miedema, S.A. & Jong, P.S. de & Wittekoek, S., "On the Closing Process of Clamshell Dredges in Water Saturated Sand (Adobe Acrobat 4.0 PDF-File 1 MB)". Proc. WODCON XIII, Bombay, India, 1992. This paper was given the IADC Award for the best technical paper on the subject of dredging in 1992.
33. Becker, S. & Miedema, S.A. & Jong, P.S. de & Wittekoek, S., "The Closing Process of Clamshell Dredges in Water Saturated Sand (Adobe Acrobat 4.0 PDF-File 1 MB)". Terra et Aqua No. 49, September 1992, IADC, The Hague.
34. Miedema, S.A., "Modeling and Simulation of Dredging Processes and Systems". Symposium "Zicht op Baggerprocessen", Delft University of Technology, Delft, The Netherlands, 29 October 1992.
35. Miedema, S.A., "Dredmo User Interface, Operators Manual". Report: 92.3.GV.2995. Delft University of Technology, 1992, 77 pages.
36. Miedema, S.A., "Inleiding Mechatronica, college WBM202" Delft University of Technology, 1992.
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
37. Miedema, S.A. & Becker, S., "The Use of Modeling and Simulation in the Dredging Industry, in Particular the Closing Process of Clamshell Dredges", CEDA Dredging Days 1993, Amsterdam, Holland, 1993.
38. Miedema, S.A., "On the Snow-Plough Effect when Cutting Water Saturated Sand with Inclined Straight Blades (Adobe Acrobat 4.0 PDF-File 503 kB)". ASCE Proc. Dredging 94, Orlando, Florida, USA, November 1994. Additional Measurement Graphs. (Adobe Acrobat 4.0 PDF-File 209 kB).
39. Riet, E. van, Matousek, V. & Miedema, S.A., "A Reconstruction of and Sensitivity Analysis on the Wilson Model for Hydraulic Particle Transport (Adobe Acrobat 4.0 PDF-File 50 kB)". Proc. 8th Int. Conf. on Transport and Sedimentation of Solid Particles, 24-26 January 1995, Prague, Czech Republic.
40. Vlasblom, W.J. & Miedema, S.A., "A Theory for Determining Sedimentation and Overflow Losses in Hoppers (Adobe Acrobat 4.0 PDF-File 304 kB)". Proc. WODCON IV, November 1995, Amsterdam, The Netherlands 1995.
41. Miedema, S.A., "Production Estimation Based on Cutting Theories for Cutting Water Saturated Sand (Adobe Acrobat 4.0 PDF-File 423 kB)". Proc. WODCON IV, November 1995, Amsterdam, The Netherlands 1995. Additional Specific Energy and Production Graphs. (Adobe Acrobat 4.0 PDF-File 145 kB).
42. Riet, E.J. van, Matousek, V. & Miedema, S.A., "A Theoretical Description and Numerical Sensitivity Analysis on Wilson's Model for Hydraulic Transport in Pipelines (Adobe Acrobat 4.0 PDF-File 50 kB)". Journal of Hydrology & Hydromechanics, Slovak Ac. of Science, Bratislava, June 1996.
43. Miedema, S.A. & Vlasblom, W.J., "Theory for Hopper Sedimentation (Adobe Acrobat 4.0 PDF-File 304 kB)". 29th Annual Texas A&M Dredging Seminar. New Orleans, June 1996.
44. Miedema, S.A., "Modeling and Simulation of the Dynamic Behavior of a Pump/Pipeline System (Adobe Acrobat 4.0 PDF-File 318 kB)". 17th Annual Meeting & Technical Conference of the Western Dredging Association. New Orleans, June 1996.
45. Miedema, S.A., "Education of Mechanical Engineering, an Integral Vision". Faculty O.C.P., Delft University of Technology, 1997 (in Dutch).
46. Miedema, S.A., "Educational Policy and Implementation 1998-2003 (versions 1998, 1999 and 2000) (Adobe Acrobat 4.0 PDF_File 195 kB)". Faculty O.C.P., Delft University of Technology, 1998, 1999 and 2000 (in Dutch).
47. Keulen, H. van & Miedema, S.A. & Werff, K. van der, "Redesigning the curriculum of the first three years of the mechanical engineering curriculum". Proceedings of the International Seminar on Design in Engineering Education, SEFI-Document no.21, page 122, ISBN 2-87352-024-8, Editors: V. John & K. Lassithiotakis, Odense, 22-24 October 1998.
48. Miedema, S.A. & Klein Woud, H.K.W. & van Bemmel, N.J. & Nijveld, D., "Self Assesment Educational Programme Mechanical Engineering (Adobe Acrobat 4.0 PDF-File 400 kB)". Faculty O.C.P., Delft University of Technology, 1999.
49. Van Dijk, J.A. & Miedema, S.A. & Bout, G., "Curriculum Development Mechanical Engineering". MHO 5/CTU/DUT/Civil Engineering. Cantho University Vietnam, CICAT Delft, April 1999.
50. Miedema, S.A., "Considerations in building and using dredge simulators (Adobe Acrobat 4.0 PDF-File 296 kB)". Texas A&M 31st Annual Dredging Seminar. Louisville Kentucky, May 16-18, 1999.
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
51. Miedema, S.A., "Considerations on limits of dredging processes (Adobe Acrobat 4.0 PDF-File 523 kB)". 19th Annual Meeting & Technical Conference of the Western Dredging Association. Louisville Kentucky, May 16-18, 1999.
52. Miedema, S.A. & Ruijtenbeek, M.G. v.d., "Quality management in reality", "Kwaliteitszorg in de praktijk". AKO conference on quality management in education. Delft University of Technology, November 3rd 1999.
53. Miedema, S.A., "Curriculum Development Mechanical Engineering (Adobe Acrobat 4.0 PDF-File 4 MB)". MHO 5-6/CTU/DUT. Cantho University Vietnam, CICAT Delft, Mission October 1999.
54. Vlasblom, W.J., Miedema, S.A., Ni, F., "Course Development on Topic 5: Dredging Technology, Dredging Equipment and Dredging Processes". Delft University of Technology and CICAT, Delft July 2000.
55. Miedema, S.A., Vlasblom, W.J., Bian, X., "Course Development on Topic 5: Dredging Technology, Power Drives, Instrumentation and Automation". Delft University of Technology and CICAT, Delft July 2000.
56. Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training (Adobe Acrobat 4.0 PDF-File 1.1 MB)". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
57. Miedema, S.A., "The modelling of the swing winches of a cutter dredge in relation with simulators (Adobe Acrobat 4.0 PDF-File 814 kB)". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
58. Hofstra, C. & Hemmen, A. van & Miedema, S.A. & Hulsteyn, J. van, "Describing the position of backhoe dredges (Adobe Acrobat 4.0 PDF-File 257 kB)". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
59. Miedema, S.A., "Automation of a Cutter Dredge, Applied to the Dynamic Behaviour of a Pump/Pipeline System (Adobe Acrobat 4.0 PDF-File 254 kB)". Proc. WODCON VI, April 2001, Kuala Lumpur, Malaysia 2001.
60. Heggeler, O.W.J. ten, Vercruysse, P.M., Miedema, S.A., "On the Motions of Suction Pipe Constructions a Dynamic Analysis (Adobe Acrobat 4.0 PDF-File 110 kB)". Proc. WODCON VI, April 2001, Kuala Lumpur, Malaysia 2001.
61. Miedema, S.A. & Zhao Yi, "An Analytical Method of Pore Pressure Calculations when Cutting Water Saturated Sand (Adobe Acrobat PDF-File 2.2 MB)". Texas A&M 33nd Annual Dredging Seminar, June 2001, Houston, USA 2001.
62. Miedema, S.A., "A Numerical Method of Calculating the Dynamic Behaviour of Hydraulic Transport (Adobe Acrobat PDF-File 246 kB)". 21st Annual Meeting & Technical Conference of the Western Dredging Association, June 2001, Houston, USA 2001.
63. Zhao Yi, & Miedema, S.A., "Finite Element Calculations To Determine The Pore Pressures When Cutting Water Saturated Sand At Large Cutting Angles (Adobe Acrobat PDF-File 4.8 MB)". CEDA Dredging Day 2001, November 2001, Amsterdam, The Netherlands.
64. Miedema, S.A., "Mission Report Cantho University". MHO5/6, Phase Two, Mission to Vietnam by Dr.ir. S.A. Miedema DUT/OCP Project Supervisor, 27 September-8 October 2001, Delft University/CICAT.
65. (Zhao Yi), & (Miedema, S.A.), "
" (Finite Element Calculations To Determine The Pore Pressures When Cutting Water
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
Saturated Sand At Large Cutting Angles (Adobe Acrobat PDF-File 4.8 MB))". To be published in 2002.
66. Miedema, S.A., & Riet, E.J. van, & Matousek, V., "Theoretical Description And Numerical Sensitivity Analysis On Wilson Model For Hydraulic Transport Of Solids In Pipelines (Adobe Acrobat PDF-File 147 kB)". WEDA Journal of Dredging Engineering, March 2002.
67. Miedema, S.A., & Ma, Y., "The Cutting of Water Saturated Sand at Large Cutting Angles (Adobe Acrobat PDF-File 3.6 MB)". Proc. Dredging02, May 5-8, Orlando, Florida, USA.
68. Miedema, S.A., & Lu, Z., "The Dynamic Behavior of a Diesel Engine (Adobe Acrobat PDF-File 363 kB)". Proc. WEDA XXII Technical Conference & 34th Texas A&M Dredging Seminar, June 12-15, Denver, Colorado, USA.
69. Miedema, S.A., & He, Y., "The Existance of Kinematic Wedges at Large Cutting Angles (Adobe Acrobat PDF-File 4 MB)". Proc. WEDA XXII Technical Conference & 34th Texas A&M Dredging Seminar, June 12-15, Denver, Colorado, USA.
70. Ma, Y., Vlasblom, W.J., Miedema, S.A., Matousek, V., "Measurement of Density and Velocity in Hydraulic Transport using Tomography". Dredging Days 2002, Dredging without boundaries, Casablanca, Morocco, V64-V73, 22-24 October 2002.
71. Ma, Y., Miedema, S.A., Vlasblom, W.J., "Theoretical Simulation of the Measurements Process of Electrical Impedance Tomography". Asian Simulation Conference/5th International Conference on System Simulation and Scientific Computing, Shanghai, 3-6 November 2002, p. 261-265, ISBN 7-5062-5571-5/TP.75.
72. Thanh, N.Q., & Miedema, S.A., "Automotive Electricity and Electronics". Delft University of Technology and CICAT, Delft December 2002.
73. Miedema, S.A., Willemse, H.R., "Report on MHO5/6 Mission to Vietnam". Delft University of Technology and CICAT, Delft Januari 2003.
74. Ma, Y., Miedema, S.A., Matousek, V., Vlasblom, W.J., "Tomography as a Measurement Method for Density and Velocity Distributions". 23rd WEDA Technical Conference & 35th TAMU Dredging Seminar, Chicago, USA, june 2003.
75. Miedema, S.A., Lu, Z., Matousek, V., "Numerical Simulation of a Development of a Density Wave in a Long Slurry Pipeline". 23rd WEDA Technical Conference & 35th TAMU Dredging Seminar, Chicago, USA, june 2003.
76. Miedema, S.A., Lu, Z., Matousek, V., "Numerical simulation of the development of density waves in a long pipeline and the dynamic system behavior". Terra et Aqua, No. 93, p. 11-23.
77. Miedema, S.A., Frijters, D., "The Mechanism of Kinematic Wedges at Large Cutting Angles - Velocity and Friction Measurements". 23rd WEDA Technical Conference & 35th TAMU Dredging Seminar, Chicago, USA, june 2003.
78. Tri, Nguyen Van, Miedema, S.A., Heijer, J. den, "Machine Manufacturing Technology". Lecture notes, Delft University of Technology, Cicat and Cantho University Vietnam, August 2003.
79. Miedema, S.A., "MHO5/6 Phase Two Mission Report". Report on a mission to Cantho University Vietnam October 2003. Delft University of Technology and CICAT, November 2003.
80. Zwanenburg, M., Holstein, J.D., Miedema, S.A., Vlasblom, W.J., "The Exploitation of Cockle Shells". CEDA Dredging Days 2003, Amsterdam, The Netherlands, November 2003.
81. Zhi, L., Miedema, S.A., Vlasblom, W.J., Verheul, C.H., "Modeling and Simulation of the Dynamic Behaviour of TSHD's Suction Pipe System by using Adams". CHIDA Dredging Days, Shanghai, China, november 2003.
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
82. Miedema, S.A., "The Existence of Kinematic Wedges at Large Cutting Angles". CHIDA Dredging Days, Shanghai, China, november 2003.
83. Miedema, S.A., Lu, Z., Matousek, V., "Numerical Simulation of the Development of Density Waves in a Long Pipeline and the Dynamic System Behaviour". Terra et Aqua 93, December 2003.
84. Miedema, S.A. & Frijters, D.D.J., "The wedge mechanism for cutting of water saturated sand at large cutting angles". WODCON XVII, September 2004, Hamburg Germany.
85. Verheul, O. & Vercruijsse, P.M. & Miedema, S.A., "The development of a concept for accurate and efficient dredging at great water depths". WODCON XVII, September 2004, Hamburg Germany.
86. Miedema, S.A., "THE CUTTING MECHANISMS OF WATER SATURATED SAND AT SMALL AND LARGE CUTTING ANGLES". International Conference on Coastal Infrastructure Development - Challenges in the 21st Century. HongKong, november 2004.
87. Ir. M. Zwanenburg , Dr. Ir. S.A. Miedema , Ir J.D. Holstein , Prof.ir. W.J.Vlasblom, "REDUCING THE DAMAGE TO THE SEA FLOOR WHEN DREDGING COCKLE SHELLS". WEDAXXIV & TAMU36, Orlando, Florida, USA, July 2004.
88. Verheul, O. & Vercruijsse, P.M. & Miedema, S.A., "A new concept for accurate and efficient dredging in deep water". Ports & Dredging, IHC, 2005, E163.
89. Miedema, S.A., "Scrapped?". Dredging & Port Construction, September 2005. 90. Miedema, S.A. & Vlasblom, W.J., " Bureaustudie Overvloeiverliezen". In opdracht
van Havenbedrijf Rotterdam, September 2005, Confidential. 91. He, J., Miedema, S.A. & Vlasblom, W.J., "FEM Analyses Of Cutting Of Anisotropic
Densely Compacted and Saturated Sand", WEDAXXV & TAMU37, New Orleans, USA, June 2005.
92. Miedema, S.A., "The Cutting of Water Saturated Sand, the FINAL Solution". WEDAXXV & TAMU37, New Orleans, USA, June 2005.
93. Miedema, S.A. & Massie, W., "Selfassesment MSc Offshore Engineering", Delft University of Technology, October 2005.
94. Miedema, S.A., "THE CUTTING OF WATER SATURATED SAND, THE SOLUTION". CEDA African Section: Dredging Days 2006 - Protection of the coastline, dredging sustainable development, Nov. 1-3, Tangiers, Morocco.
95. Miedema, S.A., "La solution de prélèvement par désagrégation du sable saturé en eau". CEDA African Section: Dredging Days 2006 - Protection of the coastline, dredging sustainable development, Nov. 1-3, Tangiers, Morocco.
96. Miedema, S.A. & Vlasblom, W.J., "THE CLOSING PROCESS OF CLAMSHELL DREDGES IN WATER-SATURATED SAND". CEDA African Section: Dredging Days 2006 - Protection of the coastline, dredging sustainable development, Nov. 1-3, Tangiers, Morocco.
97. Miedema, S.A. & Vlasblom, W.J., "Le processus de fermeture des dragues à benne preneuse en sable saturé". CEDA African Section: Dredging Days 2006 - Protection of the coastline, dredging sustainable development, Nov. 1-3, Tangiers, Morocco.
98. Miedema, S.A. "THE CUTTING OF WATER SATURATED SAND, THE SOLUTION". The 2nd China Dredging Association International Conference & Exhibition, themed 'Dredging and Sustainable Development' and in Guangzhou, China, May 17-18 2006.
99. Ma, Y, Ni, F. & Miedema, S.A., "Calculation of the Blade Cutting Force for small Cutting Angles based on MATLAB". The 2nd China Dredging Association
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
International Conference & Exhibition, themed 'Dredging and Sustainable Development' and in Guangzhou, China, May 17-18 2006.
100. ,"" (download). The 2nd China Dredging
Association International Conference & Exhibition, themed 'Dredging and Sustainable Development' and in Guangzhou, China, May 17-18 2006.
101. Miedema, S.A. , Kerkvliet, J., Strijbis, D., Jonkman, B., Hatert, M. v/d, "THE DIGGING AND HOLDING CAPACITY OF ANCHORS". WEDA XXVI AND TAMU 38, San Diego, California, June 25-28, 2006.
102. Schols, V., Klaver, Th., Pettitt, M., Ubuan, Chr., Miedema, S.A., Hemmes, K. & Vlasblom, W.J., "A FEASIBILITY STUDY ON THE APPLICATION OF FUEL CELLS IN OIL AND GAS SURFACE PRODUCTION FACILITIES". Proceedings of FUELCELL2006, The 4th International Conference on FUEL CELL SCIENCE, ENGINEERING and TECHNOLOGY, June 19-21, 2006, Irvine, CA.
103. Miedema, S.A., "Polytechnisch Zakboek 51ste druk, Hoofdstuk G: Werktuigbouwkunde", pG1-G88, Reed Business Information, ISBN-10: 90.6228.613.5, ISBN-13: 978.90.6228.613.3. Redactie: Fortuin, J.B., van Herwijnen, F., Leijendeckers, P.H.H., de Roeck, G. & Schwippert, G.A.
104. MA Ya-sheng, NI Fu-sheng, S.A. Miedema, "Mechanical Model of Water Saturated Sand Cutting at Blade Large Cutting Angles", Journal of Hohai University Changzhou, ISSN 1009-1130, CN 32-1591, 2006. 绞刀片大角度切削水饱和沙的力学模型, 马亚生[1] 倪福生[1] S.A.Miedema[2], 《河海大学常州分校学报》-2006年20卷3期 -59-61页
105. Miedema, S.A., Lager, G.H.G., Kerkvliet, J., “An Overview of Drag Embedded Anchor Holding Capacity for Dredging and Offshore Applications”. WODCON, Orlando, USA, 2007.
106. Miedema, S.A., Rhee, C. van, “A SENSITIVITY ANALYSIS ON THE EFFECTS OF DIMENSIONS AND GEOMETRY OF TRAILING SUCTION HOPPER DREDGES”. WODCON ORLANDO, USA, 2007.
107. Miedema, S.A., Bookreview: Useless arithmetic, why environmental scientists can't predict the future, by Orrin H. Pilkey & Linda Pilkey-Jarvis. Terra et Aqua 108, September 2007, IADC, The Hague, Netherlands.
108. Miedema, S.A., Bookreview: The rock manual: The use of rock in hydraulic engineering, by CIRIA, CUR, CETMEF. Terra et Aqua 110, March 2008, IADC, The Hague, Netherlands.
109. Miedema, S.A., "An Analytical Method To Determine Scour". WEDA XXVIII & Texas A&M 39. St. Louis, USA, June 8-11, 2008.
110. Miedema, S.A., "A Sensitivity Analysis Of The Production Of Clamshells". WEDA XXVIII & Texas A&M 39. St. Louis, USA, June 8-11, 2008.
111. Miedema, S.A., "An Analytical Approach To The Sedimentation Process In Trailing Suction Hopper Dredgers". Terra et Aqua 112, September 2008, IADC, The Hague, Netherlands.
112. Hofstra, C.F., & Rhee, C. van, & Miedema, S.A. & Talmon, A.M., "On The Particle Trajectories In Dredge Pump Impellers". 14th International Conference Transport & Sedimentation Of Solid Particles. June 23-27 2008, St. Petersburg, Russia.
113. Miedema, S.A., "A Sensitivity Analysis Of The Production Of Clamshells". WEDA Journal of Dredging Engineering, December 2008.
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema
114. Miedema, S.A., "New Developments Of Cutting Theories With Respect To Dredging, The Cutting Of Clay And Rock". WEDA XXIX & Texas A&M 40. Phoenix Arizona, USA, June 14-17 2009.
115. Miedema, S.A., "A Sensitivity Analysis Of The Scaling Of TSHD's". WEDA XXIX & Texas A&M 40. Phoenix Arizona, USA, June 14-17 2009.
116. Liu, Z., Ni, F., Miedema, S.A., “Optimized design method for TSHD’s swell compensator, basing on modelling and simulation”. International Conference on Industrial Mechatronics and Automation, pp. 48-52. Chengdu, China, May 15-16, 2009.
117. Miedema, S.A., "The effect of the bed rise velocity on the sedimentation process in hopper dredges". Journal of Dredging Engineering, Vol. 10, No. 1 , 10-31, 2009.
118. Miedema, S.A., “New developments of cutting theories with respect to offshore applications, the cutting of sand, clay and rock”. ISOPE 2010, Beijing China, June 2010.
119. Miedema, S.A., “The influence of the strain rate on cutting processes”. ISOPE 2010, Beijing China, June 2010.
120. Ramsdell, R.C., Miedema, S.A., “Hydraulic transport of sand/shell mixtures”. WODCON XIX, Beijing China, September 2010.
121. Abdeli, M., Miedema, S.A., Schott, D., Alvarez Grima, M., “The application of discrete element modeling in dredging”. WODCON XIX, Beijing China, September 2010.
122. Hofstra, C.F., Miedema, S.A., Rhee, C. van, “Particle trajectories near impeller blades in centrifugal pumps. WODCON XIX, Beijing China, September 2010.
123. Miedema, S.A., “Constructing the Shields curve, a new theoretical approach and its applications”. WODCON XIX, Beijing China, September 2010.
124. Miedema, S.A., “The effect of the bed rise velocity on the sedimentation process in hopper dredges”. WODCON XIX, Beijing China, September 2010.
Randall, R. & Jong, P. de & Miedema, S.A., "Experience with cutter suction dredge simulator training". Texas A&M 32nd Annual Dredging Seminar. Warwick, Rhode Island, June 25-28, 2000.
Copyright: Dr.ir. S.A. Miedema