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(DME 311)

B.Tech DEGREE EXAMINATION, DECEMBER 2011.

(Examination at the end of Third Year)

Mechanical Engineering

Paper I – OPERATIONS RESEARCH

Time : Three hours Maximum : 75 marks

Answer Question No. 1 Compulsorily. (15 1 = 15)

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

1. Write brief note on :

(a) Explain surplus and slack variables.

(b) What do you understand by a linear programming problem?

(c) Degeneracy in LPP.

(d) Limitations of OR models.

(e) What are the basic characteristics of queue system?

(f) Explain the main phases of OR study.

(g) Dominance property in game theory.

(h) Differentiate CPM and PERT networks.

(i) Describe a pay off matrix in game theory.

(j) Pure and mixed strategies.

(k) What are the rules to be followed in the construction of a net work?

(l) How do you solve a game when saddle point does not exist?

(m) What is graphical optimization?

(n) What is crash duration?

(o) Applications of OR.

UNIT I

2. (a) State the limitations of the graphical method of solving a LPP.

(b) Solve the following by dual simplex method :

Max. 213 xxZ

Subject to the constraints :

.0,

232

1

21

21

21

xx

xx

xx

Or

(DME 311) 2

3. (a) What is meant by degeneracy in linear programming and indicate how can it be resolved?

(b) Solve the following LPP graphically.

Max. 21 35 xxZ

Subject to :

.0

1025

1553

21

21

21

xx

xx

xx

UNIT II

4. Solve the following transportation problem, the matrix represents the tij

To

Fro

m

W1 W2 W3 W4 Availability

A 6 7 3 7 5

B 7 9 1 5 7

C 6 5 16 7 8

D 18 9 10 2 10

Demand 10 5 10 5

Or

5. (a) Discuss the characteristics of queueing systems.

(b) There are five pumps available for developing five wells. The efficiency of each pump in producing the maximum yield at each pump is shown in the following table. In what way should the pumps be assigned to wells so as to maximize the overall efficiency.

Wells

Pu

mps

1 2 3 4 5

1 45 40 65 30 5

2 50 30 25 60 30

3 25 20 15 20 40

4 35 25 30 25 20

5 80 60 60 75 50

(DME 311) 3

UNIT III

6. (a) What is the basic object of CPM and PERT technique?

(b) For the following data,

(i) Compute the project completion time

(ii) Crash the project to 7 weeks at the least cost.

Activity Preceding Normal time (days) Crash time (days) Nomal Cost Crash Cost

Activity Rs. Rs.

A – 3 2 1000 1600

B – 2 1 2000 2700

C – 1 1 300 300

D A 7 3 1300 1600

E B 6 3 850 1000

F C 2 1 4000 5000

G D, E 4 2 1500 2000

Or

7. Following are the manpower requirements for each activity in a project :

Activity 1-2 1-3 2-4 2-6 3-4 4-5 4-6 5-7 6-7 7-8

Time (days) 10 11 13 14 10 7 17 13 9 1

Manpower per day 2 3 4 3 1 3 3 5 8 11

(a) Draw the network diagram and find out total float and free float for each activity.

(b) The contractor stipulates that during the first 26 days, only 4 to 5 men and during remaining days 8 to 11 men only can be made available. Rearrange the activities suitable for leveling the man power resources to satisfy the above condition.

UNIT IV

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

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

B1 B2 B3

A1 1 7 2

A2 6 2 7

A3 5 1 6

Or

(DME 311) 4

9. Use dynamic programming to solve the L.P.P :

Maximize 2121 810, xxxxf

Subject to

252 21 xx

10

4522

2

21

x

xx

.0,0 21 xx

—————————

(DME 312)

B.Tech. DEGREE EXAMINATION, DECEMBER 2011.

Second Year


Paper II — DESIGN OF MACHINE ELEMENTS


Answer Question No. 1 compulsorily. (15)

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

1. (a) Distinguish between sequential design and concurrent design.

(b) How will you find out allowable stress for brittle parts using factor of safety?

(c) What is the difference between S-N curves for ferrous and non-ferrous components?

(d) What is self locking of power screw? What is the condition for self-locking? (3)

(e) What are the advantages of pre loading of bolts?

(f) What are the methods of Non- destructive testing of welded joints?

(g) Explain the principle of wedge action used in cotter joint.

(DME 312) 2

UNIT I

2. (a) What is optimal design? Explain developed design and functional design.

(b) State the allowing elements added to steel to get alloy steels and the effect they produce.

Or

3. The principal stresses induced at appoint in a machine component made of steel 50C4 (Syt = 460 Nmm2) are as follows : 2/2001 mmN

2/1502 mmN 03 . Calculate the factor of safety by

(a) the maximum shear stress theory and

(b) the distortion energy theory.

UNIT II

4. A circular bar of 500 mm length is supported freely at its two ends. It is acted upon by a central concentrated cyclic load having a minimum value of 2000 kgf and a maximum value of 5000 kgf. Determine the diameter of bar by taking a factor of safety of 1.5, size effect 0.85, surface finish factor of 0.9. the material properties of bar are given by: ultimate strength of 6 kgf/mm2, yield strength of 50 kgf/mm2 and endurance strength of 35 kgf/mm2.

Or

(DME 312) 3

5. Design a screw jack for load carrying capacity 100kN. Lifting weight is 0.5m

UNIT III

6. (a) Explain the procedure of designing a longitudinal and circumferential joint of a boiler.

(b) A 65 mm diameter solid shaft is to be welded to a flat plate by a fillet weld around the circumference of the shaft. Determine the size of the weld if torque on the shaft is 3 kN –m. The allowable shear stress in the weld is 70 MPa

Or

7. (a) What are the advantages of seam welding over spot welding

(b) Two mild steel tie rods having width 200 mm and thickness 12.5mm are to be connected by means of riveted joint with double cover plates. Design the joint if the permissible stresses are 80 MPa in tension and 65 MPa in shear and 160MPa in crushing.

UNIT IV

8. Design a cotter joint to support a load varying from 20 kN in tension to 30 kN in compression. The following allowable stresses may be used for the material of the joint used . tensile stress = compressive stress 50 MPa; shear stress =35 MPa; crushing stress =90 MPa.

Or

(DME 312) 4

9. Explain the following:

(a) Determine the size of the bolt when the bracket carries an eccentric load perpendicular to the axis of bolt.

(b) A heat treated nut has greater strength, but a soft nut is usually preferred why?

——————

(DME 313)




Paper III — MACHINE DYNAMICS



Answer ONE question from each Unit.

(4 15 = 60)

1. (a) What do you mean by equivalent offset inertia force? Explain.

(b) Explain equivalent offset inertia force.

(c) What do you mean by primary and secondary unbalance in reciprocating engines?

(d) What do you mean by spin, precession and gyroscopic planes?

(e) Discuss the effectiveness of a band and block brake with the help of a neat sketch. Deduce the relation for ratio of tight and slack side tensions.

(DME 313) 2

(f) How does a Porter governor differ from that of a Watt governor?

(g) What is meant by effort and power of a governor? Find the expressions for the same in a porter governor.

UNIT I

2. A vertical single – cylinder single – acting Diesel engine has a cylinder 12 in. diameter and a stroke of 18 in. The reciprocating parts weigh 500 lb, the connecting rod is 40 in. long and the r.p.m. are 240. The ratio of compression is 14 and the pressure remains constant during the injection of the oil for one — tenth of and expansion is 1.35, find the effective turning moment on the crankshaft when the crank makes an angle of 75 with the IDC.

Or

3. A constant torque 2.5 kW motor drives a riveting machine. The mass of the moving parts including the flywheel is 125 kg at 700 mm radius. One riveting operation absorbs 1000 J of energy and takes one second. Speed of the flywheel is 240 rpm before riveting. Determine

(a) The number of rivets closed per hour, and

(b) The reduction in speed after the riveting operation.

(DME 313) 3

UNIT II

4. The cylinders of a V – engine are set at an angle of 40 with both cylinders connected to a common crank. The connecting rod is 300 mm long and the crank radius is 60 mm. The reciprocating mass is 1 kg per cylinder whereas the rotating mass at the crank pin is 1.5 kg. A balance mass equivalent to 1.8 kg is also fitted opposite to the crank at a radius of 80 mm. Determine the maximum and the minimum values of the primary and secondary forces due to inertia of the reciprocating and rotating masses if the engine rotates at 900 rpm.

Or

5. In a four – crank symmetric engine, the reciprocating masses of the two extreme cylinder sets, A and D, are each 0.8 ton and those of the two inner cylinder sets, B and C, are each 1.2 tons. Taking the direction of crank A as 0°, find the angles, measured clockwise, between A and the other three cranks so that the balance of the engine will be complete except for secondary couples. Find also the ratio pitch of outside cylinders to pitch of inside cylinders.

UNIT III

6. Describe with sketches one form of torsion dynamometer and explain in detail the calculations involved in finding the HP transmitted. How would you proceed to calibrate the dynamometer?

Or

(DME 313) 4

7. A rear engine automobile is travelling along a curved track of 120 m radius. Each of the four wheels has a moment of inertia of 2.2 kg.m2 and an effective diameter of 600 mm. The rotating parts of the engine have a moment of inertia 1.25 kg.m2. The gear ratio of the engine to the back wheel is 3.2. The engine axis is parallel to the rear axle and the crankshaft rotates in the same sense as the road wheels. The mass of the vehicle is 2050 kg and the centre of mass is 520 mm above the road level. The width of the track is 1.6 m. What will be the limiting speed of the vehicle if all the four wheels maintain contact with the road surface?

UNIT IV

8. Each arm of a Porter governor is 300 mm long and is pivoted on the axis of rotation. Each ball has a mass of 6 kg and the sleeve weighs 18 kg. The radius of rotation of the ball is 200 mm when the governor begins to lift and 250 mm when the speed is maximum. Determine the maximum and the minimum speeds and the range of speed of the governor.

Or

9. (a) How does a Porter governor differ from that of a Watt governor?

(b) Explain the difference between governor and flywheel.

——————————

(DME 314)




Paper IV – HYDRAULIC MACHINES


Answer Question No. 1 compulsorily. (5 3 = 15)


1. (a) What are the few basic differences between turbine and pump?

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

(c) What is an air vessel? Describe the function of air vessel for reciprocating pump.

(d) What is priming of centrifugal pump?

(e) Draw a neat sketch of hydruaulic lift.

UNIT I

2. (a) Derive the expression for workdone per second in the case of a radial curved vane.

(DME 314) 2

(b) A jet of water coming out of a nozzle of diameter 5 cm with a velocity at 30m/s strikes a vertical moving plate. The plate velocity along the jet direction is 6m/s. Find the

(i) force acting on the plate

(ii) workdone by the jet per minute.

Or

3. A jet of water strikes to moving blade which has a velocity of 10m/s. The jet enters the blade at an angle 30 and leaves at 160 to the direction of blade motion. If the absolute velocity of Jet at the entry is 25m/s. Find

(a) The blade angles at entry and exit

(b) Work done per kg of water

(c) Efficiency UNIT II

4. A peton wheel is having a mean bucket diameter of 1m and is running at 1000 r.p.m. The net head on the pelton wheel is 700m. If the side clearance angle is 15 and discharge through nozzle is 0.1m3/s. Find :

(a) Power available at the nozzle, and

(b) Hydraulic efficiency of the Turbine.

Or

(DME 314) 3

5. (a) Explain unit speed, unit discharge and unit power of hydraulic Turbines.

(b) A turbine is to operate under a head of 25m of 200 r.p.m. The discharge is 9m3/s. If the over all efficiency is 90%, determine :

(i) Power generated

(ii) Specific speed of the turbine

(iii) Type of turbine.

UNIT III

6. (a) Explain the functions of air vessels in reciprocating pump.

(b) A single acting reciprocating pump, running at 50 r.p.m. delivers 0.00736m3/s of water. The diameter of the piston is 200 mm and stroke 300mm. The section and delivers heads are 3.5m and 11.5m. Determine :

(i) Theoretical discharge

(ii) Coefficient of discharge

(iii) Percentage slip of the pump and

(iv) Power required to run the pump.

Or

7. (a) Derive an expression for the specific speed of a centrifugal pump.

(DME 314) 4

(b) Find the number of pumps required to take water from a deep well under a total head of 89m. All the pumps are identical and are running at 800 r.p.m. The specific speed of each pump is given as 25 while the rated capacity of each pump is 0.16m3/s.

UNIT IV

8. (a) What do you mean by dimensionless numbers? Name any four dimensional numbers.

(b) State Buckingham's -Theorem. What do you mean by repeating variables? How are the repeating variables selected in dimensional analysis.

Or

9. (a) Explain with a sketch the working of a hydraulic ram and define efficiency of the ram.

(b) An accumulator has a ram of area 2m2 and lift of 10m. Find the capacity of the accumulator, if the water is supplied at a pressure of 15N/cm2.

————————

(DME 315)



MECHANICAL ENGINEERING

Paper V — I.C ENGINES AND GAS TURBINES


Answer Question No. 1 Compulsorily.

(15 1 = 15)


(4 15 = 60)

1. Answer the following.

(a) What do you mean by swept volume?

(b) What do you mean by gasoline engine?

(c) What are the functions of a float in a carburetor?

(d) Name the ports used in two stroke engines.

(e) How do you determine the radiation heat lost from an IC engine?

(f) Write an equation which represents the incomplete combustion in IC engines.

(g) Name any two alcohols used in IC engines.

(h) Draw a typical graph “Torque versus Brake power” of a constant speed diesel engine.

(i) What do you mean by the term “chemical delay” refers to combustion in CI engines?

(j) How much is the octane number (approximately) of petrol produced in India?

(k) State the applications of a rotary air compressor.

(l) What do you mean by whirl?

(m) Name the gaseous fuels (at least two) used in gas turbines.

(n) What is the effect of friction on efficiency of a gas turbine?

(o) Define the term “propulsive efficiency” of a rocket engine.

(DME 315) 2

UNIT I

2. (a) With neat sketches, describe the working principle of a four stoke petrol engine. (8)

(b) Draw a typical valve timing diagram of a disel engine. And explain the importance of valve overlap. (7)

Or

3. (a) With a neat sketch, describe the constructional features and working principle of a fuel pump used in diesel engines. (10)

(b) Describe the constructional features of a two stroke petrol engine. (5)

UNIT II

4. (a) Draw a typical curve “brake specific fuel consumption versus engine speed” and explain the significance of this curve. (7)

(b) A six cylinder, four stroke, gasoline engine having a bore of 90 mm and a stroke of 100 mm has a compression ratio of 7. The relative efficiency is 55%, when the indicated specific fuel consumption is 300 gm.kW-h. Estimate

(i) the calorific value of the fuel, and

(ii) fuel consumption, if the indicated mean effective pressure is 8.5 bar and the speed is 2500 rpm (8)

Or

5. (a) Find the brake specific fuel consumption (in kg/kW-h) of a diesel engine whose fuel consumption is 5 grams per second, when the power output is 80 kW. Also calculate the indicated specific fuel consumption of the engine, if the mechanical efficiency is 75%. (6)

(b) List out the fuels (liquid and gaseous) used in modern IC engines. Compare their important characteristics (9)

UNIT III

6. (a) Draw a neat diagram ‘‘(pressure versus crank angles)’’ and explain the various stages of combustion in diesel engines. (8)

(b) With a neat sketch, describe the working principle of a centrifugal compressor. (7)

Or

7. (a) Explain the phenomenon of knock in SI engines. (7)

(b) In an axial flow air compressor producing a producing a pressure ratio of 6/1 with air entering at 20 °C. The mean velocity of the rotor blades is 200 m/s and the inlet and exit angles of both fixed and moving blades (at mean radius) are 45 and 15° respectively. The degree of reaction (at mean radius) is 50%, the work done factor is 0.86 throughout. The number of stages is 12 and the axial velocity may be taken as constant throughout the compressor. Determine the isentropic efficiency of the compressor. (8)

(DME 315) 3

UNIT IV

8. (a) With the help of T-s diagram, describe the effect of regeneration on the efficiency of a Brayton cycle. (9)

(b) A gas turbine plant operates on the Brayton cycle between Tmin =30°C and Tmax = 800 °C. Find the maximum network done per kg of gas, and corresponding efficiency of the cycle. Assume the specific heat ‘Cp’ of the gas is 1.005 kJ/kg-K and the gas constant ‘R’ is 0.287 kJ/kg-K. (6)

Or

9. (a) With the help of ‘p-v’ and ‘T-s’ diagrams, explain the effect of

(i) inter cooling and

(ii) reheating, on the performance of a Brayton cycle. (9)

(b) What is a rocket? How is it propelled? Name the solid fuels (at least two) used in rocket engines. (6)

———————

(DME 316)




Paper VI — METAL CUTTING AND MACHINE TOOLS


Answer question No. 1 compulsorily. (15 1 = 15)


1. (a) How do you classify the automats based on their cycle control?

(b) What are the major specifications of a center lathe?

(c) Sketch a tool post using in lathe.

(d) What is a jig boring machine called so?

(e) In what respect does a coated abrasive differ from abrasive wheel?

(f) What is the shell end mill?

(g) What is thread milling?

(DME 316) 2

(h) State true or false. Justify your answer.

Diamond can be used for machining of

ferrous alloys.

(i) Which coolants would you suggest to for

turning of following metals with HSS tools?

(i) Aluminum

(ii) Copper.

(j) What are the types of HSS?

(k) What is optimum tool life?

(l) List out the types of chips.

(m) What is Built-Up-Edge?

(n) State the important functions of cutting

fluids.

(o) What is crater wear?

UNIT I

2. (a) Differentiate between a turret and capstan

lathe. (7)

(b) How the temperature in machining affects

the tool life? (8)

Or

(DME 316) 3

3. During the machining of mild steel with 0–10–

8–8–90–2 mm ORS shaped carbide tool, the

following observations were made. Depth of cut =

2.0 mm; feed = 0.2 mm / rev; cutting speed =

150 m/min; chip thickness = 0.4 mm; tangential

force = 320 N; axial force = 170 N. Calculate (15)

(a) Shear force and normal force on shear plane.

(b) Friction force and normal force on rake face.

(c) Kinetic coefficient of friction and

(d) Specific energy in cutting.

UNIT II

4. (a) Explain the types of Drill. Draw neat sketch

of each. (7)

(b) Explain the crank and slotted lever quick

return mechanism of a shaper. (8)

Or

5. (a) Explain construction and working of a radial

drilling machine. (7)

(b) Explain any one of the quick return

mechanism in a planner. (8)

(DME 316) 4

UNIT III

6. (a) Explain the salient features of universal milling machine. (7)

(b) With neat sketches explain cutters used on milling machines. (8)

Or

7. (a) Explain the simple indexing mechanism with an example. (7)

(b) Classify the milling machines and explain the operations performed on universal milling machines. (8)

UNIT IV

8. (a) Explain the mechanisms of tool wear. (7)

(b) Discuss the factors which influence machinability. (8)

Or

9. (a) Discuss the generating in turning. (7)

(b) Derive the expression for tool life for maximum production rate. (8)

——————

(DME 321)




Paper I — OPERATIONS MANAGEMENT




1. Write a brief note on the following :

(a) Exponential smoothing technique.

(b) Heuristic model of aggregate planning.

(c) Inventory costs.

(d) Types of control charts.

(e) EOQ models.

UNIT I

2. What is a production system? Explain the different types of production systems.

3. Explain the regression and correlation methods of forecasting.

(DME 321) 2

UNIT II

4. What is aggregate production planning? Why is it required?

5. Explain the objectives and functions of master production schedule.

UNIT III

6. (a) What is materials management? What are the objectives of good materials management system?

(b) What is MRP? Explain the flow of information in MRP.

7. (a) What is inventory control? Explain the functions of inventory control.

(b) Discuss the effect of the provision of safety stock on inventory.

UNIT IV

8. (a) Draw a neat sketch of an OC curve showing its different zones. Also explain the characteristics of OC curve.

(b) Explain how to compute the reliability of series and parallel systems.

9. (a) Discuss the multiple sampling plan.

(b) What is the need for ISO 9000 standards? What are the various certifications under this umbrella of ISO 9000?

———————–––

(DME 322)




Paper II — DESIGN OF TRANSMISSION ELEMENTS


Answer Question No. 1 compulsorily. (15 marks)


Design Data Books are allowed.

1. (a) What undesirable features does an Oldham type coupling possess?

(b) How the shaft is designed when it is subjected to twisting moment only?

(c) Distinguish between full and partial bearings.

(d) Define eccentric ratio in hydrodynamic journal bearing.

(e) What is the effect of centrifugal tension on power transmitted by a belt drive.

(f) How is the axial thrust in helical gears overcome?

(g) Why worm gear reduction units are not preferred over other types of gear boxes for transmitting large power?

(DME 322) 2

UNIT I

2. (a) What is Gib-head taper sunk key? What is its advantages?

(b) A solid circular shaft is subjected to a bending moment of 30000 kgf-cm and a

torque of 100000 kgf-cm. The shaft is made of C-45 steel having ultimate tensile stress of 7000 kgf/cm2 and a ultimate shear stress of 5000 kgf/cm2. The factor of safety is 6, determine the diameter of the shaft.

Or

3. Design a muff coupling for transmitting 45 kW at speed of 350 rpm. The muff is made of cast iron and is used to connect two shafts. The allowable shear stress in the material of the shaft is 50 N/mm2. The material of the key and shaft is same and coupling is required to transmit 25% over load. Allowable shear stress for cast iron is 16 N/mm2.

UNIT II

4. (a) What is the most important characteristics of Babbitt and aluminum as a bearing materials?

(DME 322) 3

(b) Calculate the dynamic load rating of a deep groove ball bearing which carries a radial load of 350 kg and a thrust load of 300 kg at 1750 rpm. The service is 8 hr/day and the bearing is to be designed for life 18,000 hours with no more than 10% failures.

Or

5. (a) Explain the procedure of selection of bearings from manufacturer’s catalogue.

(b) Design a journal bearing for a centrifugal pump running at 1440 rpm, diameter of journal is 10 cm and the load on each bearing is 2000 kg. The factor ZN/P may be taken as 2800 for centrifugal pump bearings.

UNIT III

6. (a) State the factors for deciding the coefficient of friction between belt and pulley.

(b) A V-belt drive is required for a 700 kW, 1750 rpm electric motor, which drives a centrifugal pump running at 1200 rpm for a service of 24 hrs per day. From space considerations the centre distance should not be greater than 1.2 m.

Determine :

(i) Belt specification

(ii) Number of belts

(iii) Pulley diameters.

Or

(DME 322) 4

7. A compressor is to be actuated from 10 kW electric motor. The speed of the motor is 1000 rpm and the compressor speed being 350 rpm. The minimum centre distance is 500 mm. The compressor operates 16 hrs per day. Design a suitable chain.

UNIT IV

8. Design a pair of spur gear with 20 full-depth involute teeth consisting of a teeth Pinion meshing with a 50 teeth gear. The pinion shaft is connected to a 22.5 kW, l450 rpm electric motor. The starting torque of the motor can be taken as 150% of the rated torque. The material of the pinion is plain carbon steel Fe 410 (Sut = 410 N/mm2), while the gear is made of grey cast iron FG 200 (Sut = 200 N/mm2). The factor of safety is 1.5.

Or

9. Explain the following :

(a) How will you decide the directions of three components of resultant tooth force in bevel gears?

(b) A pair of worm gear is designed as 3/60/10/6. The worm rotates at 1440 rpm and the normal pressure angle is 20 . Determine the coefficient of friction and the efficiency of worm gears.

———————–––

(DME 323)


(Examination at the end of Third year)


Paper III — MECHANICAL VIBRATIONS



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

1. (a) Explain Beats phenomenon?

(b) Equivalent stiffness of spring.

(c) Differentiate between coulomb damping and

viscous damping

(d) Explain forced vibrations with constant

harmonic excitation.

(e) Vibration isolation.

(f) Eigen values and Eigen vectors.

(g) Importance of principal mode of vibration.

(DME 323) 2

UNIT I

2. A body is subjected to two harmonic motions as given below :

6/cos151 tX

3/cos82 tX

What extra harmonic motion should be given to the body to bring it to static equilibrium?

Or

3. A homogeneous solid cylinder of mass m is linked by a spring of constant k and is resting on an inclined plane as shown in Fig. If it rolls without, slipping, find out its frequency of oscillation.

UNIT II

4. (a) Explain Torsional vibration.

(b) Explain logarithmic decrement.

Or

(DME 323) 3

5. In the design of a shock absorber, it is required that the overshoot is 10% of initial displacement when released from rest. Determine 1 , itf is made equal to 0.5 1 . What will be the overshoot?

UNIT III

6. A machine having a mass of 100 kg and supported on springs of total stiffness 7.84 105N/m has an unbalanced rotating element which results in a disturbing force of 392 N at a speed of 3000 rpm. Assuming a damping factor of = 0.20, determine

(a) The amplitude of motion due to unbalance,

(b) The transmissibility, and

(c) The transmitted force

Or

7. (a) Explain centrifugal pendulum absorber with a neat sketch.

(b) Explain viscous damped.

UNIT IV

8. A three rotor system of Fig. has the following physical constants.

21 90.4 mkgJ ; 2

2 80.9 mkgJ ; 2

3 86.6 mkgJ

(DME 323) 4

radmNkt /1016.2 51 ;

radmNkt /1078.0 52 ;

Find the natural frequencies of the system and the corresponding mode shapes.

Or

9. Explain the following:

(a) Raleigh Ritz method

(b) Free vibration equation of motion of multi degree freedom system.

——————

(DME 324)

B. Tech. DEGREE EXAMINATION, DECEMBER 2011.

(Examination at the end of Third Year Fourth Semester)


Paper IV — BASIC ELECTRONICS AND MICROPROCESSORS


Answer Question No. 1 compulsorily.

(15 1 = 15)


(4 15 = 60)

1. (a) What is meant by latching current?

(b) What is meant by forward biasing?

(c) What are the components of filters?

(d) What is meant by CE configuration of transistors?

(e) What is meant by reverse breakdown of zener diode?

(DME 324) 2

(f) Draw the symbol of PNP transistor indicating currents.

(g) Define current gain for CB transistor.

(h) What types of feed back does an oscillator use?

(i) What is meant by piezoelectric effect?

(j) What is the difference between decimal and BCD numbers?

(k) Draw the truth table for NAND logic.

(l) What is a microprocessor?

(m) What is meant by counter?

(n) What is a instructor?

(o) What are various I/O devices?

UNIT I

2. (a) Explain the complete characteristics of P-N junction diodes.

(b) Explain the operations of transistor as amplifier.

Or

3. (a) Explain the effect of filter circuits an output voltage waveforms. Obtain the output voltages with L-C filter.

(b) Explain the performance characteristics of UJT.

(DME 324) 3

UNIT II

4. (a) What is an oscillator? Explain various

components of oscillators.

(b) Explain the working of Colpitt’s oscillator.

Or

5. (a) Explain the principle of operations of

monostable multivibrator.

(b) Explain the working of OP-AMP integrator

circuit.

UNIT III

6. (a) Obtain NOT, AND and OR operating using

only NAND operations.

(b) Design a digital circuit for the logic equation

BABAY .. .

Or

7. (a) Explain the use of multiplexes in

combinational logic circuit design.

(b) Implement a J-K flip-flop using NAND gates.

(DME 324) 4

UNIT IV

8. Explain the internal architecture of 8085 microprocessors.

Or

9. (a) Explain the simple assembly language program development steps.

(b) Explain classifications of instruction set for 8085 microprocessors.

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(DME 325)




Paper V — HEAT TRANSFER


Answer Question No. 1 compulsorily. (15 marks)


1. (a) Define effectiveness and efficiency of the fin. (3)

(b) Write the energy equation for thermal boundary later in forced convection for a flat plate and explain various terms involved. (2)

(c) Describe the mechanism of heat flow by natural convection. (2)

(d) Derive the expression for shape factor of a cylindrical cavity with itself of diameter D and height H. (2)

(e) What are momentum and thermal eddy diffusivities? (2)

(f) How does radiation play an important role in boiling heat transfer? (2)

(g) Why is Planck’s law the basic law of thermal radiation? (2)

UNIT I

2. (a) Derive one dimensional time dependent heat conduction equation with internal heat generation and variable thermal conductivity in a rectangular coordinate system.

(b) A brass rod 100 mm long and 5 mm diameter extends horizontally from a casting at 200°C. The rod is exposed to an environment at 20°C, h = 30 W/m2K. What is the temperature at distance of 25 mm, 50 mm and 100mm from the casting?

Or

3. (a) Derive an expression for heat loss from a fin whose length approaches infinity.

(b) A square plate heater 15 cm 15 cm is inserted between two slabs. Slab A is 2 cm thick (K =50 W/mK) and slab B is 1 cm thick (K=0.2W/mK). The outside heat transfer coefficient on both sides of A and B are 200 and 50 W/m2K respectively. The temperature of the surrounding air is 25°C, if the rating of the heater is 1kW, determine

(i) Maximum temperature of the system

(ii) Outer surface temperature of two slabs.

(DME 325) 2

UNIT II

4. (a) A tomato with diameter D and thermal conductivity K, initially at a uniform

temperature is suddenly dropped into boiling water at T with very large convection

coefficient. Develop a mathematical formulation of the problem for determining the

temperature distribution within the tomato.

(b) Derive Reynolds Colbourn’s analogy for laminar flow over a plate.

Or

5. (a) A 50 mm thick iron plate is initially at 225C. Both surfaces are suddenly exposed to

25°C with a convection coefficient of 500 W/m2k.

(i) Calculate the centre temperature 2 minute after start of exposure

(ii) Calculate the temperature at a depth of 10 mm from the surface 2 minute after

exposure.

(b) Water at 20°C was flowing over a plate of uniform heat flux of 9000 W/m2. The flow

velocity was 200 mm/s. The length of the plate was 1.3 m. Determine the temperature

of the plate.

UNIT III

6. (a) Calculate the cooling capacity by natural convection in air of a heat sink, having four

rectangular thin fins of size 20 mm 25 mm. The fins may be assumed to have a

constant surface temperature of 60°C in ambient air of 20°C. Take fin efficiency as 60%.

(b) Water at 225 kg/h is to be heated from 35°C to 95°C by means of concentric tube heat

exchanger. Oil at 225 kg/h and 210°C with a specific heat of 2095 J/kgK is to be used as

hot fluid. If the overall heat transfer coefficient based on the outer diameter of the

inner tube is 550 W/m2K, determine the length of the heat exchanger, if the outer

diameter is 100 mm.

Or

7. (a) A horizontal 40W fluorescent tube which is 3.8cm in diameter and 120 cm long stands

in still air at 1 atm and 20°C, If the surface temperature is 40°C and radiation is

neglected, what percentage of power is being dissipated by convection.

(b) One tonne window air conditioner removes 3.5 kW heat from a room and in process, it

rejects 4.2 kW heat in an air cooled condenser. The ambient temperature is 30°C, where

as the refrigerant condenser at 45°C. For the condenser, the product of overall heat

transfer coefficient and corresponding area is 350 W/K. Calculate the temperature rise

of air as it flows over the condenser tubes.

(DME 325) 3

UNIT IV

8. (a) Derive an expression for total emissive power of a black body.

(b) Explain why sky is blue in the day and sunset is yellow orange.

Or

9. (a) What is a black body, what are its properties? Why does a cavity with a small hole

behave as a black body?

(b) Two parallel disc 50 mm in diameter are spaced 40 cm apart with one disc directly

above the other disc. One disc is maintained at 500C and the other at 227C. The

emissivities of the discs are 0.2 and 0.4 respectively. The disc is located in a very large

room whose walls are maintained at 67C. Determine the rate of heat loss by radiation

from the inside surface of each disc.

–––––––––––

(DME 326)




Paper VI ENGINEERING METROLOGY


Answer Question No. 1 compulsorily. (7 2 = 14)


1. Write brief note about the following :

(a) Explain the term ‘Accuracy’.

(b) What are the objectives of engineering metrology?

(c) Define least count of vernier Caliper.

(d) What precautions should be taken while using slip gauges?

(e) Define Pitch.

(f) Define Backlash.

(g) Describe any one method of measuring effective diameter of internal threads.

(DME 326) 2

UNIT I

2. (a) What do you understand by fit? What are

types of fits? Draw neat sketches stating the

practical examples of each. (8)

(b) Compare line standard and end standard. (7)

Or

3. (a) Explain the principles of interchangeability

and selective assembly. (7)

(b) Explicate in detail angle gauge and snap

gauge with sketches. (8)

UNIT II

4. (a) What are the sources of errors in

manufacturing of gears? (7)

(b) Explain the 3-2-1 locating concept using

pins,, with suitable sketches. Indicate where

the clamping forces are to be applied. Is this

locating concept limited to rectangular work

pieces. (8)

Or

(DME 326) 3

5. (a) Explicate gear metrology of spur gears with

reference to

(i) Lead

(ii) Pitch. (7)

(b) Define jig and fixture? What is difference

between template jig and indexing jig? (8)

UNIT III

6. (a) Elucidate the effective diameter

measurement by two wire method. (7)

(b) Explain how the straightness error of a lathe

bed is checked using auto-collimator. (8)

Or

7. (a) With help of a neat sketch describe the

principle of working of a mechanical

comparators. (8)

(b) What are the advantages and disadvantages

of electrical comparator? (7)

(DME 326) 4

UNIT IV

8. (a) What are the factors affecting surface roughness? What is the necessary for controlling the surface texture? (7)

(b) Enumerate various alignment tests on milling machine. (8)

Or

9. (a) How surface finish is measured using LASER? (7)

(b) Sketch and explain the constructional features of a bridge types co-ordinate measuring machine. (8)

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