btec-mec-03 - pdfmachine from broadgun software, http

(DME 311)

B.Tech. DEGREE EXAMINATION, MAY 2009.

(Examination at the end of Third Year)

Mechanical Engineering

Paper I � OPERATIONS RESEARCH

Time : Three hours Maximum : 75 marks

All questions carry equal marks.

Answer Question No. 1 Compulsorily.

Answer ONE question from each Unit.

1. Write brief note on :

(a) Different phases of OR.

(b) Dual problem.

(c) Degeneracy in LPP.

(d) Unbounded solution.

(e) Applications of PERT and CPM for project management.

(f) Classification of queues.

(g) Principle of optimality.

(h) CPM.

(i) Characteristics of queuing system.

(j) Dummy arrow in net work.

(k) Game theory.

(l) Pure and mixed strategies.

(m) Saddle point.

(n) Payoff matrix in game theory.

UNIT I

2. Use simplex method to solve the following problem : (14)

Max : 321 242 xxxz

Subject to the constraints :

642 321 xxx

52 321 xxx

106 21 xx

Or

3. A firm uses lathe, milling and grinder to make two machine parts. The table below

represents the machining time required for each part, the machining time available on

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(DME 311) 2

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different machines and the profit on each machine part. Find the number of Part � I and

Part � II to be manufactured per week in order to maximize the profit. (14)

Machine Machining Time

Part � I Part � II

Machining Time available per week (minutes)

Lathe 12 6 3000

Milling m/c 4 10 2000

Grinding m/c 2 5 900

UNIT II

4. Consider the problem of allocating raw materials form four different warehouses to

five different plants. The availability of the raw materials in the four warehouses are 25

tonnes, 30 tonnes, 20 tonnes and 30 tonnes. The demands of the raw material in the

five plants are 20 tonnes, 20 tonnes, 30 tonnes, 10 tonnes and 25 tonnes. It is not

possible to shift the raw materials from warehouse 4 to plant 4 because of steep road.

Unit cost of transportation (in hundred) from the warehouse to the plant is given in the

table below. Find the optimal shipping plant for the raw material. (14)

Machine

1 2 3 4 5

1 10 2 3 15 9

2 5 10 15 2 4

3 15 5 14 7 15 Op

era

tor

4 20 15 13 � 8

Or

5. Solve the following assignment problem using Branch and Bound algorithm. The

cell entries represent the efficiency of the operator to perform a job on a machine. (14)

Machine

1 2 3 4

1 30 100 60 70

2 30 50 70 50

3 50 60 70 70

Op

era

tor

4 40 60 90 100

UNIT III

(DME 311) 3

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6. A project has the following time schedule :

Activity Time in months Activity Time in months

1 � 2 2 4 � 6 3

1 � 3 2 5 � 8 1

1 � 4 1 6 � 9 5

2 � 5 4 7 � 8 4

3 � 6 8 8 � 9 3

3 � 7 5

Construct PERT network and compute :

(a) Total float for each activity

(b) Critical path and its duration. Also find the minimum number of cranes the

project must have for its activities 2 � 5, 3 � 7 and 8 � 9 without delaying the project. (14)

Or

7. (a) What is the basis object of CPM and PERT technique? (4)

(b) A small project is composed of the following activities whose time estimates

are given below : (Estimated activity duration in days)

Activity A B C D E F G H

Predecessor � A A B C, B E D F, G

Optimistic 2 8 14 4 6 6 18 8

Most likely 4 12 16 10 12 8 18 14

Pessimistic 6 16 30 16 18 22 30 32

(i) Draw the net work and find the critical path.

(ii) Compute the expected project completion time.

(iii) What is the probability that the project will require 75 days? (10)

UNIT IV

8. (a) State the general rules of dominance for two person zero�sum games. (6)

(b) Solve the game whose pay off matrix is given by : (8)

B1 B2 B3

A1 1 7 2

A2 6 2 7

A3 5 1 6

Or

(DME 311) 4

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9. Use dynamic programming to solve the L.P.P. (14)

Maximize 21 9xxz

Subject to the constraints :

252 21 xx

112 x

0, 21 xx .

��

(DME 312)




Paper II � DESIGN OF MACHINE ELEMENTS



Answer Question No. 1 compulsory.


10. (a) Define ductility and malleability.

(b) What is endurance limit?

(c) Name different types of riveted joints.

(d) What is a self locking screw?

(e) Why taper is provided in a cotter?

UNIT I

11. (a) Discuss the factors to be considered for the selection of a material.

(b) What are the different types of design? Explain them in detail.

12. (a) A hollow wrought iron rod is subjected to a tensile load of 10kN acting along

its axis. If the outside diameter and inside diameter of rod are 20mm and 15mm

respectively. Calculate the following :

(i) Safe tensile stress in the rod.

(ii) Factor of safety if the ultimate tensile stress is 300MPa.

(b) A mild steel shaft of 40 mm diameter is subjected to a pure torque at a shear

stress of 60MPa. Determine factor of safety by

(DME 311) 5

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(i) Maximum shear stress theory.

(ii) Distortion energy theory.

UNIT II

13. Calculate the diameter of a uniform circular rod subjected to a maximum load of

34kN and a minimum load of 14kN in tension. The yield stress in tension is 420MPa

and endurance limit is 320MPa. Factor of safety is 1.5. Stress concentration factor is 1.8.

14. It is required to lift a load of 3 kN by a double start acme thread of 6 mm pitch and

40 mm diameter at the rate of 0.6 m/min. The end of the screw is carried on a thrust

collar 50 mm outside diameter and 28 mm inside diameter. If coefficient of friction is

0.13, calculate the power of the motor to drive the slide.

UNIT III

15. Design a triple riveted double cover plate with unequal cover plates butt joint for

longitudinal seam of a boiler if the inside diameter of largest course of the drum is 1m

and steam pressure is 1.9 MPa. Assume the allowable stresses as = 60 MPa, t = 80

MPa, c = 130 MPa. The efficiency of the joint is 70%. The corrosion allowance is 1mm.

16. A bracket supports a load of 26 kN and is welded to a vertical member by four

fillets as shown in figure 1. Determine the size of weld if stress in throat section is not to

exceed 80 MPa. The throat section may be take as 0.707 times size of weld.

Figure 1

UNIT IV

17. Discuss in detail about the design of bolted joints under eccentric loading.

18. Design a cotter joint to connect two rods of equal diameter transmitting an axial

force of 60kN. The safe stresses for cotter and rods are as follows :

= 45 MPa, t = 70 MPa, c = 110 MPa.

��

(DME 311) 6

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(DME 313)




Paper III � MACHINE DYNAMICS


Answer Question No. 1 compulsorily.



19. (a) State and explain D'Alembert's principle.

(b) What is meant by dynamic unbalance in machinery?

(c) What is the principle of transmission dynamometer?

(d) What are spin, precession and gyroscopic planes?

(e) What is meant by isochronism in a governor?

UNIT I

20. Derive expressions for velocity and acceleration of piston in a slider-crank

mechanism.

21. The crank and connecting rod of a vertical single cylinder gas engine running at

1800 rpm are 60 mm and 240 mm respectively. The diameter of the piston is 80 mm

and the mass of the reciprocating parts is 1.2 kg. At a point during the power stroke

when the piston has moved 20 mm from the top dead centre position, the pressure on

the piston is 800 kN/m2. Determine

(a) the net force on the piston

(b) the thrust in the connecting rod

(c) the thrust on the sides of cylinder walls

(d) the engine speed at which the above values are zero.

UNIT II

22. Three masses of 8 kg, 12 kg and 15 kg attached at radial distances of 80 mm, 100

mm and 60 mm respectively to a disc on a shaft are in complete balance. Determine the

angular positions of the masses 12 kg and 15 kg relative to 8 kg mass.

23. The cylinders of a twin V-engine are set at 60 angle with both pistons connected

to a single crank through their respective connecting rods. Each connecting rod is 600

(DME 311) 7

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mm long and the crank radius is 120 mm. The total rotating mass is equivalent to 2 kg

at the crank radius and the reciprocating mass is 1.2 kg per piston. A balance mass is

also fitted opposite to the crank equivalent to 2.2 kg at a radius of 150 mm. Determine

the maximum and minimum values of the primary and secondary forces due to inertia of

the reciprocating and the rotating masses if the engine speed is 800 rpm.

UNIT III

24. (a) With the help of a neat sketch, explain the construction and working principle

of a rope brake dynamometer.

(b) The following data refer to a laboratory experiment with rope brake :

Diameter of the flywheel = 1 m

Diameter of the rope = 10 mm

Dead weight on the brake = 50 kg

Speed of the engine = 180 rpm

Spring balance reading = 120 N

Find the power of the engine.

25. Each wheel of a four-wheeled, rear engine automobile has a moment of inertia of

2.4 kg-m2 and an effective diameter of 660 mm. The rotating parts of the engine has a

moment of inertia of 1.2 kg-m2. The gear ratio of the engine to the back wheel is 3 to 1.

The engine axis is parallel to the rear axle and the crank shaft rotates in the same sense

as the road wheels. The mass of the vehicle is 2200 kg and the centre of the mass is

550mm above the road level. The track width of the vehicle is 1.5 m. Determine the

limiting speed of the vehicle around a curve with 80 m radius so that all the four wheels

maintain contact with the road surface.

UNIT IV

26. In a Porter governor, each of the four arms is 400 mm long. The upper arms are

pivoted on the axis of the sleeve, whereas the lower arms are attached to the sleeve at a

distance of 45 mm from the axis of rotation. Each ball has a mass of 8 kg and the load on

the sleeve is 60 kg. What will be the equilibrium speeds for the two extreme radii of 250

mm and 300 mm of rotation of the governor balls?

27. In a spring-controlled gravity governor, the mass of each ball is 1.6 kg. Distance of

fulcrum from the axis of rotation is 60 mm. The bell-crank lever has a vertical arm 120

mm long and a horizontal arm 50 mm long. The mass of the sleeve is 6.5 kg. The sleeve

begins to rise at 200 rpm and the rise of sleeve for 5% increase is 9 mm. Determine the

initial thrust in the spring and its stiffness.

��

(DME 314)



(DME 311) 8

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Paper IV � HYDRAULIC MACHINES




(5 3 = 15)

Answer ONE question from each Unit. (4 15 = 60)

28. (a) What is the difference between Turbine and Pump?

(b) What is meant by impulse Turbine?

(c) Why is draft tube used in reaction turbine?

(d) Define unit power and unit speed w.r.t. hydraulic turbine.

(e) What is priming of a centrifugal pump?

UNIT I

29. (a) Derive an expression for the force exerted by a Jet of water on a fixed vertical

plate in the direction of Jet.

(b) A Jet of water, 75 mm in diameter, issues with a velocity of 30 m/s and

impinges on a stationary flat plate. Find the force exerted by the Jet on the plate and

work done.

Or

30. (a) Derive an expression for the force exerted by a Jet striking at the centre of a

symmetrial curved vane.

(b) A Jet of water coming out of a nozzle of diameter 5 cm with a velocity of 30

m/s strikes to a vertical moving plate. The plate velocity along the jet direction is 6 m/s.

Find the

(i) Force acting on the plate

(ii) Work done by the Jet perminute.

UNIT II

31. (a) Draw and explain the characteristic curves of water turbine.

(b) An impulse Turbine, at best Speed Produces 100 kW under a head of 64 m.

By what percent should the speed be increased for a head of 81 m?

Or

32. (a) Define specific speed of a turbine. Derive the expression for specific speed of a

turbine.

(DME 311) 9

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(b) Explain briefly the reasons for fitting a draft tube to a reaction turbine and

sketch three common types.

UNIT III

33. (a) Explain briefly the working of a single acting reciprocating pump with a neat

sketch.

(b) Explain the functions of air vessels fitted to the saction and delivery pipes of

a reciprocating pump.

Or

34. (a) Name and define the different types of efficiences of a centrifugal pump.

(b) Write about multi stage pumps.

UNIT IV

35. (a) What are the types of similarities and explain them briefly.

(b) A Turbine develops 350 kW under a head of 90 metres at 200 rpm. What

would be its normal speed and output under head of 72 meters?

Or

36. (a) Explain briefly about Hydraulic ram.

(b) Write short notes on:

(i) Hydraulic intensifier

(ii) Hydraulic Accumulator.

��

(DME 315)




Paper V � I.C. ENGINES AND GAS TURBINES

Time :Three hours Maximum : 70 marks

Answer Question No. 1 compulsorily. (1 14 = 14)


37. Explain the following :

(a) Valve timing diagram for S.I engines

(b) Air-fuel ratio

(c) Cetane number

(DME 311) 10

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(d) Mean effective pressure

(e) Liquid fuels

(f) Ignition delay

(g) Specific thrust

(h) Stalling

(i) Indicated power

(j) Principle of jet propulsion

(k) Polytropic efficiency

(l) Combustion reactions for gaseous fuels

(m) Working cycle of gas turbines

(n) Choking.

UNIT I

38. (a) What are the differences between 2-stroke and 4-stroke engines?

(b) Explain the simple float type Carburettor with neat sketch.

Or

39. Explain with neat sketch the main components of C.I engines.

UNIT II

40. A four stroke petrol engine with a compression ratio of 6.5 to 1 and total piston

displacement of 5.2 10�3 m3 develops 100 kW brake power and consumes 33 kg of petrol

per hour of calorific value 44300 kJ/kg at 3000 r.p.m. Find (a) Brake mean effective

pressure (b) Brake thermal efficiency (c) Air standard efficiency (r = 1.4) (d) Air-fuel

ratio by mass.

Assume a volumetric efficiency of 80% one kg petrol vapour occupies 0.26 m3 at

1.013 bar and 15C. Take R for air 287 J/Kgk.

Or

41. (a) Explain solid fuels and liquid fuels.

(b) A four stroke gasoline engine develops a brake power of 410 kW. The engine

consumes 120 kg of fuel in one hour and the air consumption is 40 kg/min. If the

mechanical efficiency is 87% and fuel heating value is 43,000 kJ/kg. Determine (i) Air-

fuel ratio (ii) Indicated and brake thermal efficiency.

UNIT III

42. (a) Explain :

(i) Normal combustion

(ii) Abnormal combustion of SI engines.

(b) Draw the velocity vector diagram of a centrifugal compressor using your own

notations.

(DME 311) 11

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Or

43. (a) Explain combustion knocking in CI engines.

(b) An axial flow compressor, with compression ratio as 5, draws air at 20C

delivers it at 50C. Assuming 50% degree of reaction, find the velocity of flow if the blade

velocity is 100 m/s. Also find the number of stages. Take work factor = 0.85, = 10,

= 40 and 1pc kJ/kgK.

UNIT IV

44. (a) Explain the gas turbine cycles with intercooling and reheating.

(b) A gas turbine plant consists of two stage compressor with perfect intercooler

and a single stage turbine. If the plant works between the temperature limits of 300 k

and 1000 k and 1 bar and 16 bar. Find the net power of plant per kg of air. Take 1pc

kJ/kgK.

Or

45. (a) Derive and explain the overall thermal efficiency of a jet engine.

(b) Explain the various types of Rocket Jet propulsions.

��

(DME 316)




Paper VI � METAL CUTTING AND MACHINE TOOLS



Answer Question No. 1 is compulsory.


46. Write a short note on :

(a) Define machine tool.

(b) Lathe mechanisms

(c) Classification of lathe

(d) Applications of drilling

(e) Specifications of shaper

(DME 311) 12

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(f) Feed mechanism in planning

(g) Grinding wheel materials

(h) Dressing of grinding wheel

(i) Types of milling machines

(j) Milling operations

(k) Principle of Indexing in milling.

(l) Types of chips

(m) Calculation of tool life

(n) Requirements of tool materials

UNIT I

47. (a) What parameters can consider for selection of machine tools? Explain.

(b) What are the different mechanisms used in lathe? Explain any one with

diagram.

Or

48. (a) Explain and draw the lathe machine with indication of different parts.

(b) How can you prepare the taper turning and threading on lathe machine?

Explain.

UNIT II

49. (a) Explain the principle of operation of the drilling machine.

(b) Discuss briefly with diagram the quick return mechanism in shaping

machine.

Or

50. (a) Write the classification of different planning machines. Explain any one in

detail.

(b) Discuss the different types of super finishing operations by grinding wheel.

UNIT III

51. (a) Describe the working of a universal milling machine with neat sketch.

(b) What are the advantages and disadvantages of up milling and down milling?

Or

52. (a) Write the different indexing methods used in milling machine. Explain any

one.

(b) Discuss the different milling cutters with the advantages and applications.

UNIT IV

53. (a) Write the Nomenclature of the single point cutting tool with neat sketch.

(b) With neat sketch explain the merchant force circle theory.

Or

(DME 311) 13

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54. (a) How to determine the shear angle and chip thickness ratio? Explain.

(b) What are the various cutting fluids used in metal cutting? Explain.

��

(DME 321)




Paper I �OPERATIONS MANAGEMENT



(1 14 = 14)



55. (a) Batch production.

(b) Forecasting Variables.

(c) Correlation Coefficient.

(d) Short range plan.

(e) Inputs.

(f) Master scheduling formation.

(g) Mathematical planning.

(h) Buffer stock.

(i) Inventory control.

(j) Bill of materials.

(k) U-chart.

(l) Quality control.

(m) Acceptance sampling.

(n) MTBF.

UNIT I

56. (a) Explain the concept of production. What are the various functions of

production?

Or

(b) Outline the various methods of forecasting.

UNIT II

(DME 311) 14

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57. (a) What is aggregate planning? Briefly explain the methods of aggregate

planning.

Or

(b) Discuss clearly the various methods of Master Scheduling.

UNIT III

58. (a) What is an inventory? What are the different types of inventories?

Or

(b) What is Materials Requirement Planning (MRP)? Discuss the importance of

Materials Requirement planning.

UNIT IV

59. (a) Distinguish between single sampling and double sampling.

Or

(b) What is Reliability? Outline the factors affecting Reliability?

��

(DME 322)




Paper II � DESIGN OF TRANSMISSION ELEMENTS





60. Answer in brief :

(a) Strength of a key.

(b) Classification of bearings.

(c) Advantages and disadvantages of chain drive.

(d) Crowning of pulleys.

(e) Herringbone gears.

UNIT I

(DME 311) 15

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61. A shaft 1.2 m long is supported at the ends in bearings. Two pulleys each of weight

5 kg and each of diameter 1 m are mounted on the shaft 150 mm from each end of shaft.

The pulleys are belt driven from below and angle of lap for each pulley is 160. If the

shaft transmits 9 kW at 200 rpm. Calculate suitable diameter of shaft. Take coefficient

of friction for belt and pulley as 0.3 and permissible shear stress as 40 MPa.

62. Design a clamp coupling for a shaft of diameter 60 mm. The power to be

transmitted by the shaft is 30 kW at 200 rpm. The allowable shear stress in shaft and

key is 40 MPa and the permissible tensile stress in bolt is 65 MPa. The coefficient of

friction between shaft and muff is 0.3. The two halves of the coupling are to be connected

by 8 bolts. Crushing stress in key is 100 MPa.

UNIT II

63. (a) Discuss the advantages of rolling contact bearings over journal bearings.

(b) A ball bearing has a desired life of 8000 Hrs for a speed of 400 rpm and a

radial load of 4200 N. Determine the specific dynamic capacity.

64. It is required to design a journal bearing for a centrifugal pump running at 1200

rpm. The journal is of 80 mm and load on each journal is 18 kN. The factor ZN/P for

bearing is 2600. The length and diameter ratio is 1.2. Take correction factor as 0.002.

The bearings and atmospheric temperatures are 80 C and 30 C respectively.

UNIT III

65. Design a 6 19 steel wire rope for a vertical mine hoist to lift 1400 tonnes of coal

from a depth of 600 metres in each 8 hours shift. The rope velocity is 600 m/min and

acceleration and deceleration periods are 10 seconds and a rest period of 12 seconds for

discharging and loading. The safety factor should be at least 6. Assume a two

compartment shaft with the hoisting skips in balance.

66. A flat belt is required to transmit 30 kW at 600 rpm to a machine pulley 1200 mm

diameter. The distance between the pulley centres is 3 m and speed reduction is 3.

Service factor is 1.5. The belt is 10 mm thick and the safe stress in belt material is 2.5

MPa. Assume 3.0 . Determine width and length of the belt.

UNIT IV

67. Design a bevel gear drive between two shafts whose axis are at right angles. The

power at gear shaft is 60 kW and the gear is made of forged steel with an allowable

static stress of 160 MPa. The speed of pinion shaft is 300 rpm and that of gear shaft is

150 rpm. Pinion has 24 full depth teeth of 20 mm module and pressure angle 20.

Neglect overhang of gears.

(DME 311) 16

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68. A motor shaft transmits 14 kW at 1200 rpm to a low speed shaft with a speed

reduction of 3. The teeth are 1421 involute with 24 teeth on the pinion. Both gear and

pinion are made of heat treated steel and the maximum allowable static stress in gear

and pinion is 220 MPa. The starting torque is 30% more than running torque and the

safe shear stress in shaft and key is 45 MPa. Design a suitable spur gear drive.

��

(DME 323)




Paper III � MECHANICAL VIBRATIONS





69. (a) What are the different types of vibrations? Explain.

(b) What is meant by logarithmic decrement?

(c) Explain the different types of damping.

(d) Explain about vibration isolation.

(e) Explain about co-ordinate coupling.

UNIT I

70. Determine the equivalent spring stiffness and the natural frequency of the

following vibrating systems when (figures 1(a) to 1(e)) :

(a) the mass of the suspended to a spring

(DME 311) 17

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(b) the mass is suspended at the bottom of the two springs in series

(c) the mass is fixed in between two springs

(d) the mass is fixed to the midpoint of a spring

(e) the mass is fixed to a point on a bar joining free ends of two springs. Take

51s N/mm, 82s N/mm, m = 10kg, a = 20 mm and b = 12 mm.

(a) (b) (c) (d)

(e)

Figure 1

71. Determine the natural frequency of the simple pendulum of length L, mass m, if

the mass of rod is

(a) negligible

(b) not negligible.

UNIT II

72. A machine weighting 180 N is mounted on springs and dashpots. The equivalent

stiffness of the spring is 88 N/cm and the equivalent damping is 1.2 N s/cm. If the

system is initially at rest and a velocity of 10 cm/s is imparted to the mass, determine :

(a) The displacement and velocity of the mass as a function of time

(DME 311) 18

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(b) The displacement and velocity after 1 sec.

73. A mass of 50 kg is supported by an elastic structure of total stiffness 20 kN/m. The

damping ratio of the system is 0.2. A simple harmonic distributing force acts on the

mass and at any time t seconds. The force is 60 N. Find the amplitude of vibration and

phase angle caused by the damping.

UNIT III

74. A refrigerator unit having a mass of 35 kg is to be supported on three springs, each

having a spring stiffness s. The unit operates at 480 rpm. Find the value of stiffness s if

only 10% of the shaking force is allowed to be transmitted to the supporting structure.

75. Explain the construction and working of a centrifugal pendulum absorber. Derive

all the necessary equations.

UNIT IV

76. Figure 2 shows a rigid bar with its centre of mass not coinciding with its geometric

center, i.e. 21 11 , and supported by two springs. It represents a two-DOF system, since

two coordinates are necessary to describe its motion. The choice of the coordinates will

define the type of coupling that can be immediately determined from the mass and

stiffness matrices. Mass or dynamical coupling exists if the mass matrix is non diagonal,

whereas stiffness or static coupling exists if the stiffness matrix is non diagonal. It is

also possible to have both forms of coupling.

Figure 2

77. Explain in detail the Dunkerley�s method.

��

(DME 324)



(DME 311) 19

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Paper IV � BASIC ELECTRONICS AND MICROPROCESSORS


Answer ALL questions.

Question No. 1 is Compulsory.


78. (a) Explain the term doping and its need.

(b) What is Avelanche breakdown and Zener breakdown?

(c) How does the junction capacitance of a varactor diode vary with the variation

in Reverse bias voltage?

(d) Draw the circuit diagram of a bridge Rectifier and explain its working.

(e) Determine the base of the numbers in each case for the following operations

to be correct.

(i) 62/5 = 12

(ii) 24 + 17 = 40

(f) Simplify the following Boolean expressions to a minimum number of literals.

(i) xyz + x'y + xyz'

(ii) x'z' + xyz + xz'

(g) Realize a three input NOR gate using two input NOR gates only.

(h) What are the general purpose registers in 8085?

(i) Draw the 4:1 multiplexer realization of a full subtractor.

(j) What is the size of address bus in 8085?

(k) What is transition capacitance in PN junction diode?

(l) MOV A,B is how many byte instruction?

(m) What are the various addressing modes in 8085?

(n) Write the characteristic table of RS flip flop.

UNIT I

79. (a) Draw the circuit diagram of FET and explain its operation. Plot its transfer

characteristics and calculate md

gandr, .

(b) An N - channel JFET has a pinch off voltage of -4.5 V and mAIDSS

9 at

what value of will IDS equal to 3 mA? What is its gm this DS

I ?

Or

(DME 311) 20

ws 3

80. (a) Draw the energy band diagram of P-type, N-type silicon indicating the

energy level, band gap and the value of band gap. Mention two �P� type and two N-type

of impurities in silicon.

(b) A specimen of Ge at 300°k for which the density of carriers is 2.5 x 1013/cm3 is

doped with impurity atoms such that there is one impurity atom for 106 Ge atoms. All

the impurity atoms may be assumed ionized. The resistivity of the doped material is

0.039-cm. Carrier mobility for Ge at 300°k is 3600. For the doped material, find the

electron and hole densities e = 1.602 x l0-19C.

UNIT II

81. (a) Draw and explain the circuit of op-amp as summer.

(b) Explain Wein bridge oscillator.

Or

82. (a) Explain Colpitts oscillator.

(b) Draw and explain op-amp as differentiator.

UNIT III

83. (a) Express the following function in product of maxterms. F(u,v,w,x) =

vx+u�x+vx.

(b) Obtain simplified POS expression for the following function using K-map

f (A,B,C,D) = m (0,1,2,6,8,10,11,12).

Or

84. (a) Explain with the circuit of a look ahead carry generator.

(b) Draw the circuit and explain the operation of a magnitude comparator.

UNIT IV

85. Explain the architecture of 8085 microprocessor with a neat block diagram.

Or

86. Write short notes on interfacing 8085 to input and output devices.

��

(DME 325)




(DME 311) 21

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Paper V � HEAT TRANSFER


Answer ALL questions.

Question No. 1 is compulsory.



87. (a) What is difference between Conduction and Convection?

(b) What do you mean by thermal conductivity?

(c) Briefly explain about Drag co-efficient.

(d) What is meant by transiant heat conduction?

(e) What is the prandatal number? Show that it is a dimensionless quantity.

(f) What is the Stefan-boltzman law?

(g) Define LMTD.

UNIT I

88. (a) What is meant by thermal resistance? Explain the electrical analogy for

solving heat transfer problems.

(b) A wall of 0.5m thickness is to be constructed from a material which has an

average thermal conductivity of 1.4w/mk. The wall is to be insulated with a material

having an average thermal conductivity of 0.35w/mk so that the heat loss per square

meter will not exceed 1450w. Assuming that the inner and outer surface temperature

1200C and 15C respectively, calculate the thickness of insulation required.

Or

89. (a) Explain the different types of Extended Surfaces (FINS).

(b) One end of a very long aluminium rod is connected to wall at 140, while the

other end protrudes into a room whose air temperature is 15C. The rod is 3mm in

diameter and the heat transfer co-efficient between the rod surface and environment is

300w/m2k. Estimate the total heat dissipated by the rod taking its thermal conductivity

as 150w/mk.

UNIT II

90. (a) What is meant by transient heat conduction? Explain periodic and non

periodic heat flow.

(b) The distribution of temperature across a furnace wall 50cm thick at a certain

instant has been measured and the following curve has been fitted to the data

T = 900-300x-50x2

where x is in meters and T is inC. Taking property value as e = 2240 kg/m3, Cp =

0.8736 kJ/kgK and k = 0.58154w/mk and considering an area of 20m2, calculate

(i) The heat entering

(DME 311) 22

ws 3

(ii) The heat leaving.

Or

91. (a) What is Reynolds analogy? Describe the relation between fluid friction and

heat transfer.

(b) Water flows through a tube of 2 cm I.D. at a rate of 1.5 litres per minute.

Taking the kinematic viscosity of water as 1 10-6m2/s. Determine whether the flow is

Laminar or turbulant.

UNIT III

92. (a) Define Grashof number and explain its significance in free convection heat

transfer.

(b) A 30 cm long glass plate is hung in the air at 27C while its temperature is

maintained at 77C. Calculate the boundary layer thickness at the trailing edge of the

plate.

Or

93. (a) How are Heat exchangers classified?

(b) In a double pipe counterflow heat exchanger, 10,000 kg/h of an oil having a

specific heat of 2095 J/Kgk is cooled from 80C to 50C by 8000kg/h of water entering

at 25C. Determine the heat exchanger area for an overall heat transfer coefficient of

300w/m2k. Take Cp for water as 4180 J/Kgk.

UNIT IV

94. (a) What is the Stefan-Boltzman�s law? Explain the concept of total emissive

power of a surface.

(b) A radiator in a domestic heating system operates at a surface temperature of

55C. Determine the rate at which it emits radiant heat per unit area if it behaves as a

black body.

Or

95. (a) What are radiation shape factors and why are they used?

(b) Calculate the shape factor of a hemispherical bowl of diameter �D� with respect

to itself.

��

(DME 326)




(DME 311) 23

ws 3

Paper VI � ENGINEERING METROLOGY





96. Write a short on :

(a) Standards of length.

(b) Selection of tolerances.

(c) Interchangeability.

(d) Taylor�s principle of limit gauges.

(e) Principle of ring gauges.

(f) Differences between jig and fixture.

(g) Locating pins.

(h) Gear finishing methods.

(i) Measurement of pitch of the screw thread.

(j) Solex pneumatic comparator.

(k) Uses of straight edges.

(l) Representation of surface finish.

(m) Tomilson surface meter.

(n) Applications of CMM.

(o) Static alignment tests.

UNIT I

97. (a) Discuss briefly different types of

(i) limits

(ii) fits and

(iii) tolerances.

(b) Find the limit sizes and tolerances of hole and shaft pair designated by

710250 nH . Also estimate the type of fit. Given 250 lies in the range of 250-280 mm.

Fundamental deviation of shaft �n� = 5 D0.34.

(DME 311) 24

ws 3

Or

98. (a) With neat sketches discuss the plug gauges and ring gauges with their

applications.

(b) Explain with the help of diagram the principle of operation of sine bar.

UNIT II

99. (a) Explain the principle of operation of the six point location method?

(b) Discuss briefly the different types of jigs with suitable examples.s

Or

100. (a) Explain the process of gear shaping with the help of diagram.

(b) Discuss the various gear finishing operations.

UNIT III

101. (a) Explain the

(i) two�wire method

(ii) three- wire method with neat sketches.

(b) Explain the measurement of profile and angle of thread with neat sketch?

Or

102. (a) Describe the principle of sigma comparator with neat sketch.

(b) Discuss briefly the principle of operation of Tool maker�s microscope.

UNIT IV

103. (a) Explain about parameters of surface texture and calculation of sampling

length.

(b) Discuss briefly the operation of Taylor Hobson Talysurf with neat diagram.

Or

104. (a) Describe briefly the constructional details of Coordinate Measuring Machine.

(b) Explain the various alignment tests performed on milling machines?

��

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