FEM

IV B.Tech. I Semester Regular Examinations, November, 2011

MOBILE COMPUTING (Common to Computer Science & Engineering, Information Technology and Electronics &

Computer Engineering)

Time: 3 Hours Max Marks: 80

Answer any FIVE Questions

All Questions carry equal marks

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1. a) Explain the applications of Mobile Communications.

b) How is synchronization achieved in GSM? Who is responsible for synchronization

and why is it so important?

2. a) How are guard spaces realized between users in CDMA?

b) Define the problem of hidden and exposed terminals. What happens in the case of

such terminals if aloha, slotted aloha, reservation Aloha, or MACA is used?

3. a) What are general problems of mobile IP regarding security and support of QoS?

b) How can DHCP be used for mobility and support of Mobile IP?

4. a) Explain indirect – TCP.

b) Why is timeout freezing required in case of mobile nodes? What are the modifications

made in data link and TCP layers to enforce time-out freezing?

5. a) What are the advantages of hoarding data at the mobile device?

b) Explain query-processing architecture for processing a query using distributed

databases.

6. a) Explain hybrid data-delivery mechanism.

b) Explain other alternative methods of selective tuning and indexing techniques.

7. a) Why is routing in multi-hop ad-hoc networks complicated, what are the special

challenges?

b) How does dynamic source routing handle routing? What is the motivation behind

dynamic source routing compared to other routing algorithms from fixed networks.

8. a) Explain the functions of link manager in Bluetooth.

b) Describe J2ME features.

Code No: N0523 Set No.1 R07

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1. a) What are the limitations of mobile and wireless devices?

b) How is localization, location update, roaming etc., done in GSM and reflected in

the databases? What are typical roaming scenarios?

2. a) Explain the term interference in the space, time, frequency and code domain.

What are counter measures in SDMA, TDMA, FDMA and CDMA systems.

b) Which of the MAC schemes can give hard guarantees related to bandwidth and

access delay?

3. a) What could be quick ‘solutions’ and why don’t they work?

b) List the entities of mobile IP and describe data transfer from a mobile node to a

fixed node and vice-versa. Why and where is encapsulation needed?

4. a) Explain snooping TCP.

b) Describe slow start of congestion control. How can fast recovery take place in

the congestion avoidance phase?

5. a) Explain client-server computing with adaptation.

b) Why does a mobile device take QoS issues into account while computing?

List the object models for application adaptation for the QoS constraints.

6. a) Explain the reasons for communication asymmetry in mobile network. Give

examples of asymmetric communication architecture for data dissemination.

b) Explain index-based method of selective tuning and indexing techniques.

7. a) How does the symmetry of wireless links influence the routing algorithms proposed.

b) What are the differences between AODV and the standard distance vector algorithm?

Why are extensions needed?

8. a) Explain the MAC layer of Bluetooth.

b) Describe the wireless application environment (WAE) logical model.


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1. a) Explain the architecture of mobile computing.

b) What are the functions or authentication and encryption in GSM? How is system

security maintained?

2. a) Who performs the MAC algorithm for SDMA? What could be possible roles of

mobile stations, base stations and planning from the network provider?

b) How are guard spaces realized between users in CDMA?

3. Explain how tunneling works in general and especially for mobile IP using IP-in-IP,

minimal and generic routing encapsulation respectively. Discuss the advantages and

disadvantages of these three methods.

4. a) Explain congestion control in traditional TCP.

b) Describe transaction oriented TCP. How does the integration of connection

establishment, data transfer, and close functions into one help in transmitting and

receiving at the TCP nodes.

5. a) Explain about context-aware computing.

b) Explain the situations in which a database can crash. How does a database recover

using recovery manager? What is the role of logged entries in updating transactions?

6. a) Describe pull-based data-delivery mechanism? What are the advantages and

disadvantages of pull-based data-delivery?

b) Explain the following selective tuning and indexing techniques.

(i) Flexible indexing method (ii) Distributed index based method

7. a) What are the benefits of location information for routing in ad-hoc networks, which

problems arise?

b) What are the security threats to a MANET? Why a MANET faces greater security

threats than a fixed infrastructure network?

8. a) Explain wireless session protocol.

b) Explain different user scenarios of Bluetooth.


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1. a) What are the limitations of a GSM cell in terms of diameter and capacity (voice, data)

for the traditional GSM, HSCSD, GPRS? How can the capacity be increased?

b) What are the reasons for the delays in the GSM system for packet data traffic?

Distinguish between circuit switched and packet-oriented transmission.

2. a) What is the reason for the failure of MAC schemes in wireless networks? What is

done in wired networks to avoid this effect?

b) Explain about FDMA.

3. a) What is IP packet delivery? Explain it.

b) What is reverse tunneling? What additional routes do packets take if reverse tunneling

is required?

4. a) Compare the different types of transmission errors that can occur in wireless and wired

networks. What additional role does mobility play?

b) Explain mobile TCP. How does a supervisory host send TCP packets to the mobile

node and to a fixed TCP connection? Give the advantages and disadvantages of

mobile TCP.

5. a) Explain about power-aware computing.

b) Explain stateless and stateful cache invalidation mechanisms.

6. a) Describe push-based data-delivery mechanism. What are the advantages and

disadvantages of push-based data dissemination?


i) Directory method ii) Hash-based method

7. a) Describe the properties of MANETs.

b) Explain the dynamic source routing algorithm in MANETs.

8. a) Explain the functions of radio and baseband sublayers in Bluetooth.

b) Explain wireless transaction protocol.


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ELECTRONIC MEASUREMENTS AND INSTRUMENTATION (Electronics & Communication Engineering)




*******

1. a) Explain the terms Fidelity, Lag and Dynamic error as used for indicating instruments.

b) A PMMC instrument with a full scale deflection of 100 µA and an internal resistance

of 2000 Ω is available. It is to be converted into 0-5V, 0-10V, 0-25V, and 0-50V

multi range voltmeter using individual multiplier resistors for each range. Calculate

the values of the individual resistors.

2. a) Draw the diagram of a sine to square- wave conversion circuit using diode clipping

and explain its operation.

b) Draw a simple circuit for frequency modulating an RF signal generator and explain

its operation.

3. What is a wave analyzer? Explain the working of

i) Frequency selective ii) Heterodyne type wave analyzers.

4. a) Sketch the focusing section of a CRT and Show the equipotential lines and their

effect on electron beam.

b) Sketch the construction of a dual-beam oscilloscope and explain its operation.

5. a) Describe the procedure of frequency and time period measurement using

Lissajou figures.

b) Explain how the Time period is measured using a frequency counters.

6. a) Explain the sources of errors in a Wheatstone bridge.

b) Draw the circuit diagram of a Schearing bridge and explain its operation and

derive the equations for unknown variables.

Code No: M0421 Set No.1

R07

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7. a) Explain the principle of operation of a i) Thermocouple and ii) Sensistor.

b) With a neat diagram explain the operation of a LVDT.

8. a) Explain briefly about various pressure sensing elements.

b) What are the important factors that decide the configuration and sub system of

a DAS?


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1. a) Explain the different types of errors that may occur in measurements.

Describe their sources and precautions to minimize them.

b) A PMMC instrument with a full scale deflection of 100 µA and an internal resistance

of 1000 Ω is available. It is to be converted into a 0-5V, 0-10V, 0-25V, and 0-50V

multi range voltmeter using series-connected resistors. Calculate the values of the

multiplier resistors.

2. a) Explain the important specifications for sine/square wave generators and

Function generators.

b) Sketch the circuit and explain with waveforms an op-amp a stable multi vibrator

for use as a square-wave generator.

3. a) State and explain total harmonic distortion?

b) With a neat sketch explain the operation of a fundamental suppression harmonic

distortion analyzer.

4. a) Discuss the screen of a CRT and the factors affecting the brightness of the display.

b) Draw the block diagram of a basic oscilloscope and explain the functions of each

block.

5. a) Describe briefly about various probes used in CROs.

b) Explain how the frequency is measured using a frequency counter.

6. a) Explain the principle and working of a Q-meter.

b) Draw the circuit diagram of Maxwell’s bridge explain its operation and derive

the equations for unknown variables.


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7. a) Define gauge factor of a strain gauge and derive the expression for it.

b) Explain the working principle of a i) Thermistor and ii) RTD.

8. a) Explain the working principle of a capacitive pressure transducer.

b) Explain how an LVDT can be used to measure the pressure


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ELECTRONIC MEASUREMENTS AND INSTRUMENTATION

(Electronics & Communication Engineering)




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1. a) Explain the significance of the number of significant figures in a stated quantity

with examples.

b) Differentiate between a series type ohmmeter and a shunt type ohmmeter

2. With a block diagram explain the working of a function generator producing

sine, square and triangle waveforms.

3. a) Explain the important applications of a spectrum analyzer.

b) Explain the operation of a digital spectrum analyzer.

4. a) Explain blanking and unblanking in an oscilloscope, and discuss the need for

blanking.

b) Explain about various time delay lines used in vertical deflection section of a

CRO.

5. a) Explain how the frequency ratio of two unknown signals is measured using a

frequency counter

b) With a block diagram explain the operation of a sampling oscilloscope.

6. a) Draw the circuit diagram of a Wien bridge, explain its working and derive the

equation for frequency.

b) Explain the sources of errors and their minimizing methods in a Q-meter.

7. a) Describe the operation of a piezo-electric transducer.

b) Explain the principle of operation of a i) Thermocouple and ii) Sensistor.

8. a) Explain how an LVDT can be used to measure the displacement.

b) Draw the block diagram of a standard DAS and explain function of each block.


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1. a) What are the effects of using a voltmeter of low sensitivity? Explain with an

example.

b) Explain the working principle of a true RMS meter.

2. a) Draw a basic block diagram and waveforms for a sweep frequency generator

and explain it briefly.

b) With a block diagram explain the operation of random noise generator.

3. a) Explain with the help of block diagram the operation of a Spectrum Analyzer.

b) Explain the following terms associated with Spectrum Analyzer:

i) Sensitivity

ii) Dynamic Range

iii) Harmonic Mixing

4. a) Describe the function of each of the following oscilloscope controls

i) Focus ii) Astigmatism iii) Intensity iv) Sweep

b) Draw the block diagram of a basic horizontal deflection section and explain

each and every block.

5. a) With a block diagram explain the operation of a digital storage oscilloscope.

b) Discuss the adjustment of oscilloscope probes, and show the various waveforms

that can occur when adjusting a probe.

6. a) Draw the circuit diagram of Anderson Bridge explain it and derive the equations

for unknown variables.

b) What are the limitations of a Wheatstone bridge circuit?

7. a) With proper examples differentiate between active and passive transducers.

b) Explain the construction and working of strain gauge.

8. a) Explain the working principle of a capacitive pressure transducer.

b) What are the various configurations used in a DAS?

Code No: M0421 Set No.4 R07

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IV B.Tech I Semester Regular Examinations, November, 2011

NEURAL NETWORKS AND FUZZY LOGIC

(Common to Electrical & Electronics Engineering, Aeronautical Engineering and Instrumentation & Control Engineering) Time: 3 hours Max. Marks: 80



*****

1. a) Explain in detail about the spiking neuron model in detail.

b) Describe in detail about the historical developments to neural networks. [8+8]

2. a) Describe in detail about different learning strategies of artificial neural

networks.

b) Discuss in detail about ANN architectures in detail. [8+8]

3. a) Discuss and explain about perceptron convergence theorem.

b) Describe about the limitations and applications of perceptron models. [8+8]

4. a) “The choice of learning coefficient is a tricky task in back propagation algorithm”.

Support your answer.

b) Describe in detail about generalized delta rule. [8+8]

5. a) Give and explain about BAM stability algorithm.

b) Discuss about storage and recall algorithms in BAM training networks. [8+8]

6. a) Why fuzzy set theory is effective to tackle the problem of uncertainty? Explain.

b) Give and explain the properties of crisp sets. With a neat sketch of Venn diagrams,

discuss about the operation of crisp sets. [8+8]

7. Let 1, 2 , 3 three fuzzy sets as shown in figure 1, 2, 3. Find the aggregated fuzzy

set of 1, 2 , 3 and find the defuzzification using centroid method. [16]

Set No.1 R07 Code No. N0221

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Figure:1

Figure:2

Figure:3

8. a) Explain briefly about the process identification with reference to the feed forward

and plant inverse identification.

b) Explain different types of faults and its diagnosis using ANN. [8+8]


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1. a) Explain in detail about Hodgkin-Huxley neuron model.

b) Describe in detail about the potential applications of artificial neural networks. [8+8]

2. a) Explain what is supervised and unsupervised learning with example.

b) Explain different neuron activation functions and also compare them. [8+8]

3. a) Explain different perceptron models in detail.

b) Explain in detail about training algorithm of continuous perceptron networks. [8+8]

4. a) Explain the selection of number of hidden nodes, sigmoid gain, local minima and

learning coefficient in back propagation network.

b) State and explain in detail about kolmogorov theorem. [8+8]

5. a) Discuss in detail about hebbian learning .

b) Discuss about BAM energy function and give proof of BAM stability theorem. [8+8]

6. a) Let A=(x1,0.2),(x2,0.7),(x3,0.4) and B=(y1,0.5),(y2,0.6) be two fuzzy sets

defined on the universe of discourse X=x1,x2,x3 and Y=y1,y2,y3 respectively.

Find the Cartesian product of the A and B and fuzzy relation R.

b) Write the mathematical expression of the membership function and sketch of the

membership function. [8+8]

7. a) What is called De-fuzzification? Mention its types.

b) Explain about development of rule base and decision making system. [8+8]

8. a) Design and develop a pressure process control by FLC model. Formulate necessary

Membership functions and required fuzzy rules for the application.

b) Describe about application of neural network in fault diagnosis. [8+8]


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1. a) “An IF neuron model is considered as a special case of spiking neuron model”.

Justify your answer.

b) What are the three basic elements of a neuronal model? [8+8]

2. a) Explain in detail about activation and synaptic neural dynamics.

b) Clearly discuss different architectures of artificial neural networks. [8+8]

3. a) Discuss about training algorithms of discrete and continuous perceptron networks.

b) Explain in detail about multi-category perceptron networks. [8+8]

4. a) Give and explain about the architecture and algorithm of back propagation

network.

b) Explain about credit assignment problem in detail. [8+8]

5. a) Discuss about the following

i) Hamming distance

ii) Association rules

iii) Associative matrix

iv) Content addressable memories

b) Explain in detail about memory based learning algorithms. [8+8]

6. a) Let R,S be defined on the sets 1, 3, 5 × 1,3,5. Let R: (x, y)/y = x + 2,

S: (x, y)/x < y/. Using max min composition find

i) RoS

ii) SoR.

b) Discuss the measure of fuzziness and dissonance. [8+8]

7. a) Write about Fuzzy synthesis evaluation and Fuzzy ordering.

b) Explain MOM method for defuzzification with an example. [8+8]

8. a) Explain the application of fuzzy logic used in temperature controller of oven.

b) What are the limitations of specialized on-line learning control architecture? [8+8]


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*****

1. a) Give a brief account on biological and artificial neural networks.

b) Describe in detail about the characteristics of artificial neural networks. [8+8]

2. a) Explain Widrow-Hoff and delta learning rule in detail.

b) Give in detail about classification taxonomy of artificial neural networks. [8+8]

3. a) Illustrate the training and classification of continuous perception with an example.

b) Describe in detail about the limitations of perceptron model. [8+8]

4. a) Explain in detail how to decide the number of hidden layer neurons, input layer

neurons and output layer neurons in back propagation network.

b) Discuss in detail about learning difficulties and improvements of back propagation

algorithm. [8+8]

5. a) Describe in detail about the architecture of BAM.

b) Explain in detail about the storage and recall algorithms of Hopfield networks. [8+8]

6. a) What are the parameters to be considered for the design of membership function?

b) Write about classical set theory and classical sets. [8+8]

7. Let X=a,b,c,d Y=1,2,3,4

And = (a,0)(b,0.8)(c,0.6)(d,1)

= (1,0.2)(2,1)(3,0.8)(4,0)

=(1,0)(2,0.4)(3,1)(4,0.8)

Determine the implication relations

i) IF x is THEN y is

ii) IF x is THEN y is ELSE y is . [8+8]

8. a) Discuss about application of neural networks in load forecasting.

b) Describe the application of fuzzy logic in automobile cruise control. [8+8]


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FINITE ELEMENT METHODS

Time: 3 hours


1. Consider the following condition2 2, , 2 . = 0xx yy xy zz xz yzx y xyσ σ ε σ ε ε= = = − = =

Determine whether the compatibility equations are satisfied.

2. Find the nodal displacements in the tapered one

load of 4000 N. The cross

5 cm at the right end. Further the member experiences a temperature increase of 25

Use three 25 cm elements to idealize the member. Assume E= 2x107 N/cm

α= 6 x 10-6

cm/cm-0C.

3. Derive the equilibrium equations for t

the principle of minimum potential energy and indicate briefly the various steps involved

in your finite element derivation.

Code No. M0322


FINITE ELEMENT METHODS (Mechanical Engineering)

Max. Marks: 80



*****

onsider the following condition

, , 2 . = 0xx yy xy zz xz yzx y xyσ σ ε σ ε ε= = = − = =


Find the nodal displacements in the tapered one-dimensional member subjected to an end

The cross-sectional area decreases linearly from 10 cm 2 at the left end to

the right end. Further the member experiences a temperature increase of 25

Use three 25 cm elements to idealize the member. Assume E= 2x107 N/cm

the equilibrium equations for the beam-spring system shown in Figure


in your finite element derivation.

Set No.1R07

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Max. Marks: 80

dimensional member subjected to an end

0 cm 2 at the left end to

the right end. Further the member experiences a temperature increase of 25 0C.

Use three 25 cm elements to idealize the member. Assume E= 2x107 N/cm2, ν= 0.3 and

ring system shown in Figure. Start from


Set No.1

4. Find the stresses in the plate shown in Figure.

E= 205 GPa, ν=0.3, t=10 mm.

5. An axisymmetric ring element is shown

i) Derive the matrix [B].

ii) Derive the matrix

iii) Derive the element stiffness matrix, [K ].

6. Using a 2 X 2 rule, evaluate the integral

A x2

+ xy2) dx dy

By Gaussian quadrature, where A denotes the region shown in Figure.

Code No. M0322

the plate shown in Figure. Using one triangular membrane element.

=0.3, t=10 mm.

An axisymmetric ring element is shown in Figure.

Derive the matrix [B].

e matrix [D], for steel with E=206850 x 106 N/mm

2 and

Derive the element stiffness matrix, [K ].

2 rule, evaluate the integral


Set No.1R07

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one triangular membrane element.

and ν= 0.33.

Set No.1

7. Consider a pin fin having a diameter of

temperature is 110 °C. The ambient temperature is 4

= 21.35W/ m K

. Assume that the tip of the fin is insulated.

model, determine the temperature distribution and heat loss in the fin. (by hand

calculations).

8. Consider axial vibration of th

Develop the global stiffness and mass matrices.

By hand calculations, deter

inverse iteration algorithm.

Code No. M0322

having a diameter of 0.0079375m. and length of 0.127m

temperature is 110 °C. The ambient temperature is 40 0C and h

= 14.76

. Assume that the tip of the fin is insulated. Using a two


Consider axial vibration of the steel bar shown in Figure.

Develop the global stiffness and mass matrices.

By hand calculations, determine the lowest natural frequency and mode shape using the

inverse iteration algorithm.

Set No.1R07

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0.0079375m. and length of 0.127m. At the

= 14.76W/ m2

K Take k

Using a two-element


mine the lowest natural frequency and mode shape using the

Set No.1



Time: 3 hours


1. Consider the following condition2 2, , 2 . = 0xx yy xy zz xz yzx y xyσ σ ε σ ε ε= = = − = =


2. The stepped bar shown in Figure.

elements 1 and 2 are given by 2 and 1 in.

20x689x106 Pa, respectively.

i) Derive the stiffness matrices and the load vectors of the two elements.

ii) Derive the assembled

displacement of node C.

iii) Find the stresses induced in elements 1 and 2.

Assume the value of α for elements 1 and 2 to be 15 x 10

respectively.

3. The stepped bar shown in

Young's modulus of elements 1, 2, and a are given by 1

and 10 x 106 x 6895pa, respectively. If the cross

are given by 0.0058 , 0.00258,and 0.000645 m

Code No. M0322



Max. Marks: 80



*****

condition

, , 2 . = 0xx yy xy zz xz yzx y xyσ σ ε σ ε ε= = = − = =


stepped bar shown in Figure. is heated by 60 0C The cross-sectional areas of

elements 1 and 2 are given by 2 and 1 in. 2 and the Young's modulus by 30

, respectively.

Derive the stiffness matrices and the load vectors of the two elements.

Derive the assembled equilibrium equations of the system and find the

displacement of node C.

Find the stresses induced in elements 1 and 2.

α for elements 1 and 2 to be 15 x 10-6

and 10 x 10-6

stepped bar shown in Figure. is subjected to an axial load of 444.8 N

ments 1, 2, and a are given by 10 x 106 x 6895, 20 x 106

, respectively. If the cross-sectional areas of elements 1, 2, and 3

0.0058 , 0.00258,and 0.000645 m2. Respectively, determine the following:

Set No.2R07

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Max. Marks: 80

sectional areas of

30x689x106 and

Derive the stiffness matrices and the load vectors of the two elements.

equilibrium equations of the system and find the

per 0F

ubjected to an axial load of 444.8 N at node 2. The

, 20 x 106 x 6895,

sectional areas of elements 1, 2, and 3

. Respectively, determine the following:

Set No.2

i) Displacements of nodes 2 and 3.

ii) Stresses in elements 1. 2. and 3.

iii) Reactions at nodes 1 and 4.

4. Find the stresses in the plate shown in Figure.

5. A hexagonal plate with a circular hole is subjected to a uniform pressure on the inside

surface as shown in Figure

300- segment of the plate can be considered for the finit

Indicate a procedure for incorporating the boundary conditions along the X

Code No. M0322

Displacements of nodes 2 and 3.

Stresses in elements 1. 2. and 3.

Reactions at nodes 1 and 4.

the plate shown in Figure. Using two triangular membrane elements.

A hexagonal plate with a circular hole is subjected to a uniform pressure on the inside

surface as shown in Figure (a). Due to the symmetry of the geometry and the load,

segment of the plate can be considered for the finite element analysis [Figure

Indicate a procedure for incorporating the boundary conditions along the X

Set No.R07

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two triangular membrane elements.

A hexagonal plate with a circular hole is subjected to a uniform pressure on the inside

(a). Due to the symmetry of the geometry and the load, only a

e element analysis [Figure (b)]

Indicate a procedure for incorporating the boundary conditions along the X-and s-axes.

Set No.2

6. Figure shows a four-node quadrilateral. The

the figure. The element displacement vector q is given as

q= [0, 0, 0.20, 0, 0.15, 0.10, 0, 0.05]

Find the following:

i) The x-, y-coordinates of a point

by ξ= 0.5 and η= 0.5 and

ii) The u, v displacements of the point

7. Heat is entering into a large plate at the rate of q

mm thick. Tue outside surface of the plate is maintained at a

Using two finite elements, solve for the vector of nodal temperatures T thermal

conductivity k = 1.0 W/m

8. Determine all natural frequencies of the simply su

results obtained using a one

Code No. M322

node quadrilateral. The (x, y) coordinates of each node are given

the figure. The element displacement vector q is given as

q= [0, 0, 0.20, 0, 0.15, 0.10, 0, 0.05] T

coordinates of a point P whose location in the master element is given

η= 0.5 and

displacements of the point P.

Heat is entering into a large plate at the rate of qo = -300 W/m2 as in Fig

mm thick. Tue outside surface of the plate is maintained at a temperature of 10°C.

sing two finite elements, solve for the vector of nodal temperatures T thermal

1.0 W/m 0C.

Determine all natural frequencies of the simply supported beam shown in Fig

a one-element model

Set No.R07

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coordinates of each node are given in

in the master element is given

as in Fig.The plate is 25

temperature of 10°C.

sing two finite elements, solve for the vector of nodal temperatures T thermal

pported beam shown in Fig. Compare the

Set No.2



Time: 3 hours

All Questions

1. Consider the following state of strain

1 2 3 4 5 6, , , , 0xx yy zz yz xy zx

c x c c x c y c c yε ε ε ε ε ε= = = + + = = =

where ci, i= 1.2 . . . . . 6 are constants. Determine whether the compatibility equations are

satisfied.

2. Loads of magnitude 44.8 and 89.6

is supported by two cables as shown in Figure

areas of 1 and 2 in. 2 and Young's modulus of 30 x 106

respectively, determine the fol

i) The finite element equilibrium equations of the system by modeling each cable as

a bar element.

ii) The boundary conditions of the system.

iii) The nodal displacements of the system.

3. A three-span beam is shown in

Code No. M0322



Max. Marks: 80



*****

r the following state of strain

1 2 3 4 5 6, , , , 0xx yy zz yz xy zx

c x c c x c y c c yε ε ε ε ε ε= = = + + = = =

1.2 . . . . . 6 are constants. Determine whether the compatibility equations are

Loads of magnitude 44.8 and 89.6 N are applied at points C and D of a rigid bar AB that

o cables as shown in Figure. If cables 1 and 2 have cross

areas of 1 and 2 in. 2 and Young's modulus of 30 x 106 x 6895 and 20 x 106

respectively, determine the following:

The finite element equilibrium equations of the system by modeling each cable as

The boundary conditions of the system.

The nodal displacements of the system.

span beam is shown in Figure. Determine the deflection at the point B.

Set No.R07

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Max. Marks: 80

1.2 . . . . . 6 are constants. Determine whether the compatibility equations are

are applied at points C and D of a rigid bar AB that

. If cables 1 and 2 have cross-sectional

and 20 x 106 x 6895pa,

The finite element equilibrium equations of the system by modeling each cable as

at the point B.

Set No.3

4. Find the coordinate transformation matrix for the triangular membra

Figure.

5. If the face 23 of the element shown in Figure

200x689 Pa determine the corresponding load vector.

6. Using a 2 X 2 rule, evaluate the integral

A x2

+ xy2) dx dy

By Gaussian quadrature, where A denot

Code No. M0322

Find the coordinate transformation matrix for the triangular membrane element shown in

he element shown in Figure is subjected to a uniform pressure of

determine the corresponding load vector.

2 rule, evaluate the integral


Set No.R07

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ne element shown in

is subjected to a uniform pressure of

Set No.3

7. A steel shaft, with elliptic cross section

by an angle of θ = 20 (Figure

maximum shear stress and the torque (M

ellipse using linear triangular finite elements.

the following exact solution:

8. Determine all natural frequencies of the simply su

results obtained using a two

Code No. M0322

A steel shaft, with elliptic cross section (a=5 cm and b=3 cm) and length 1 m, is twisted

(Figure). Assuming the shear modulus as G = 80 GPa, determine the

maximum shear stress and the torque (Mz) in the shaft by modeling one-quarter

near triangular finite elements. Compare the finite element solution with

the following exact solution:

Determine all natural frequencies of the simply supported beam shown in Fig

a two-element model.

Set No.R07

3 of 3

and length 1 m, is twisted

). Assuming the shear modulus as G = 80 GPa, determine the

quarter of the

Compare the finite element solution with

pported beam shown in Fig. Compare the

Set No.3



Time: 3 hours


1. Determine whether the following displacement represents a feasible deformation state in

a solid body:

Where a is a constant.

2. If a vertical force of 4000 N along the z direction and a bending moment of 1000 N

the xz plane are developed at point A during a metal

developed in the machine too

3. Find the deflection at the load and the slopes at the ends

shown in Figure. Consider the shaft to be simply supported at bearings

Code No. M0322



Max. Marks: 80



*****

Determine whether the following displacement represents a feasible deformation state in

If a vertical force of 4000 N along the z direction and a bending moment of 1000 N

plane are developed at point A during a metal-cutting operation, find the stresses

developed in the machine tool structure shown in Figure.

Find the deflection at the load and the slopes at the ends for the steel shaft

. Consider the shaft to be simply supported at bearings A

Set No.R07

1 of 3


Max. Marks: 80

Determine whether the following displacement represents a feasible deformation state in

If a vertical force of 4000 N along the z direction and a bending moment of 1000 N-m in

cutting operation, find the stresses

for the steel shaft

A and B.

Set No.4

4. The plate shown in Figure

coefficient of expansion of the material as

mm.

5. If the element shown in Figure

temperature of 500F determine the corresponding load vector. Assume a value of

x 106 per

0F.

6. The Cartesian (global) coordinates of the corners of a triangular element are given by

(-2,-1), (2, 4), and (4, 1).

and L3. Determine the values of L1, L2, and L3 at the point, (x, y) = (0, 0).

Code No. M0322

The plate shown in Figure is heated by 500C Determine the load vector. Assume the

coefficient of expansion of the material as α= 12 x 10-6

per0C. E= 205 GPa,

he element shown in Figure is subjected to an initial strain, due to an increase in

F determine the corresponding load vector. Assume a value of

The Cartesian (global) coordinates of the corners of a triangular element are given by

1), (2, 4), and (4, 1). Find expressions for the natural (triangular) coordinates L1, L2,


Set No.4R07

2of 3

C Determine the load vector. Assume the

E= 205 GPa, ν=0.3, t=10

to an increase in

F determine the corresponding load vector. Assume a value of α = 6.5

The Cartesian (global) coordinates of the corners of a triangular element are given by

Find expressions for the natural (triangular) coordinates L1, L2,


Set No.4

7. Consider the torsion of a uniform shaf

element method, determine the stresses in the elements and the torque oil the shaft for the

following data:

Length= 1 m, G=80GPa. θ

8. By hand calculations, determine the natural frequencies

characteristic polynomial technique.

Code No. M0322

Consider the torsion of a uniform shaft with an I-section (Figure). Using the finite


Length= 1 m, G=80GPa. θ=10

By hand calculations, determine the natural frequencies for the rod in figure

characteristic polynomial technique.

Set No.4R07

3 of 3

). Using the finite


for the rod in figure using the

Set No.4

IV B.Tech. I Semester Supplementary Examinations, November, 2011






*******

1. a) Explain the applications of Mobile Communications.

b) How is synchronization achieved in GSM? Who is responsible for synchronization

and why is it so important?

2. a) How are guard spaces realized between users in CDMA?

b) Define the problem of hidden and exposed terminals. What happens in the case of

such terminals if aloha, slotted aloha, reservation Aloha, or MACA is used?

3. a) What are general problems of mobile IP regarding security and support of QoS?

b) How can DHCP be used for mobility and support of Mobile IP?

4. a) Explain indirect – TCP.

b) Why is timeout freezing required in case of mobile nodes? What are the modifications

made in data link and TCP layers to enforce time-out freezing?

5. a) What are the advantages of hoarding data at the mobile device?

b) Explain query-processing architecture for processing a query using distributed

databases.

6. a) Explain hybrid data-delivery mechanism.

b) Explain other alternative methods of selective tuning and indexing techniques.

7. a) Why is routing in multi-hop ad-hoc networks complicated, what are the special

challenges?

b) How does dynamic source routing handle routing? What is the motivation behind

dynamic source routing compared to other routing algorithms from fixed networks.

8. a) Explain the functions of link manager in Bluetooth.

b) Describe J2ME features.


1 of 1







*******

1. a) What are the limitations of mobile and wireless devices?

b) How is localization, location update, roaming etc., done in GSM and reflected in

the databases? What are typical roaming scenarios?

2. a) Explain the term interference in the space, time, frequency and code domain.

What are counter measures in SDMA, TDMA, FDMA and CDMA systems.

b) Which of the MAC schemes can give hard guarantees related to bandwidth and

access delay?

3. a) What could be quick ‘solutions’ and why don’t they work?

b) List the entities of mobile IP and describe data transfer from a mobile node to a

fixed node and vice-versa. Why and where is encapsulation needed?

4. a) Explain snooping TCP.

b) Describe slow start of congestion control. How can fast recovery take place in

the congestion avoidance phase?

5. a) Explain client-server computing with adaptation.

b) Why does a mobile device take QoS issues into account while computing?

List the object models for application adaptation for the QoS constraints.

6. a) Explain the reasons for communication asymmetry in mobile network. Give

examples of asymmetric communication architecture for data dissemination.

b) Explain index-based method of selective tuning and indexing techniques.

7. a) How does the symmetry of wireless links influence the routing algorithms proposed.

b) What are the differences between AODV and the standard distance vector algorithm?

Why are extensions needed?

8. a) Explain the MAC layer of Bluetooth.

b) Describe the wireless application environment (WAE) logical model.


1 of 1







*******

1. a) Explain the architecture of mobile computing.

b) What are the functions or authentication and encryption in GSM? How is system

security maintained?

2. a) Who performs the MAC algorithm for SDMA? What could be possible roles of

mobile stations, base stations and planning from the network provider?

b) How are guard spaces realized between users in CDMA?

3. Explain how tunneling works in general and especially for mobile IP using IP-in-IP,

minimal and generic routing encapsulation respectively. Discuss the advantages and

disadvantages of these three methods.

4. a) Explain congestion control in traditional TCP.

b) Describe transaction oriented TCP. How does the integration of connection

establishment, data transfer, and close functions into one help in transmitting and

receiving at the TCP nodes.

5. a) Explain about context-aware computing.

b) Explain the situations in which a database can crash. How does a database recover

using recovery manager? What is the role of logged entries in updating transactions?

6. a) Describe pull-based data-delivery mechanism? What are the advantages and

disadvantages of pull-based data-delivery?


(i) Flexible indexing method (ii) Distributed index based method

7. a) What are the benefits of location information for routing in ad-hoc networks, which

problems arise?

b) What are the security threats to a MANET? Why a MANET faces greater security

threats than a fixed infrastructure network?

8. a) Explain wireless session protocol.

b) Explain different user scenarios of Bluetooth.


1 of 1







*******

1. a) What are the limitations of a GSM cell in terms of diameter and capacity (voice, data)

for the traditional GSM, HSCSD, GPRS? How can the capacity be increased?

b) What are the reasons for the delays in the GSM system for packet data traffic?

Distinguish between circuit switched and packet-oriented transmission.

2. a) What is the reason for the failure of MAC schemes in wireless networks? What is

done in wired networks to avoid this effect?

b) Explain about FDMA.

3. a) What is IP packet delivery? Explain it.

b) What is reverse tunneling? What additional routes do packets take if reverse tunneling

is required?

4. a) Compare the different types of transmission errors that can occur in wireless and wired

networks. What additional role does mobility play?

b) Explain mobile TCP. How does a supervisory host send TCP packets to the mobile

node and to a fixed TCP connection? Give the advantages and disadvantages of

mobile TCP.

5. a) Explain about power-aware computing.

b) Explain stateless and stateful cache invalidation mechanisms.

6. a) Describe push-based data-delivery mechanism. What are the advantages and

disadvantages of push-based data dissemination?


i) Directory method ii) Hash-based method

7. a) Describe the properties of MANETs.

b) Explain the dynamic source routing algorithm in MANETs.

8. a) Explain the functions of radio and baseband sublayers in Bluetooth.

b) Explain wireless transaction protocol.


1 of 1

Code No: N0302/R05 Set No. 1

IV B.Tech I Semester Supplementary Examinations, November 2011CAD-CAM

( Common to Mechanical Engineering, Metallurgy & Material Technology,Production Engineering and Aeronautical Engineering)

Time: 3 hours Max Marks: 80Answer any FIVE Questions

All Questions carry equal marks⋆ ⋆ ⋆ ⋆ ⋆

1. A computer display system has a resolution of 800 horizontal x 600 vertical pixels.If the screen aspect ratio is 4: 3, show how a square box of 400 pixels can be drawn.

[16]

2. Derive the relationship between a point and its scaled counterpart p* if P is scaleduniformly about a given point Q which is not the origin. [16]

3. Find the normal vector to a cubic spline curve at any of its points. [16]

4. How do you plan for a drawing in AutoCAD. [16]

5. A turning operation is to be performed on an NC lathe. Cutting speed = 2.5 m/sec,feed = 0.2 mm/rev, and depth = 4.0 mm. Work piece diameter = 100 mm and itslength = 400 mm. Determine

(a) the rotational speed of the work bar.

(b) the feed rate,

(c) the metal removal rate and

(d) the time to travel from one end of the part to the other. [16]

6. The following table lists the weekly quantities and routings of ten parts that arebeing considered for cellular manufacturing in a machine shop. Parts are identifiedby letters and machines are identified numerically. For the data given,

(a) develop the part machine incidence matrix, and

(b) apply the rank order clustering technique to the part-machine incidence matrixto identify logical part families and machine groups. [16]

Part Weekly Quantity Machine routingA 50 3 → 2 → 7B 20 6 → 1C 75 6 → 5D 10 6 → 5 → 1E 12 3 → 2 → 7 → 4

7. Explain the typical performance reports of FMS. [16]

1 of 2


8. Why are not the JIT concepts implemented in Indian and Western foreign Indus-tries? Explain. [16]

⋆ ⋆ ⋆ ⋆ ⋆

2 of 2






1. What are the three modeling modes offered by CAD/CAM systems? What do theydo? [16]

2. A point P lies originally at the position (√

2, 0). Find its coordinates if it is rotated450 clockwise about the origin. If it is given a subsequent rotation of 450, what willits coordinates be?

3. (a) What are the limitations found in the general wire frame modeling systems?Explain with an example.

(b) What is the best kind of modeling system? Explain with suitable sketches.

(c) What are the various three-dimensional construction methods suitable for me-chanical engineering applications? [16]

4. Explain the concept of layers in AutoCAD. [16]

5. The top surface of a large cast iron plate is to be face milled. The area to bemachined is 400-mm wide and 700-mm long. The insert type face milling cutterhas eight teeth and is 100 mm in diameter. Define the origin of the axis system atthe lower left corner of the part with the long side parallel to the x-axis. Write theAPT geometry and motion statements for this job. [16]

6. A GT machine cell contains three machines Machine 1 feeds machine 2, which is thekey machine in the cell. Machine 2 feeds machine 3. The cell is set up to producea family of five parts (A, B, C, D, and E). The operation times for each part ateach machine are given in the table below. The products are to be produced in theratios 4 : 3 : 2 : 2 : 1, respectively.

(a) If 35 hrs /week are worked, determine how many of each product will be madeby the cell

(b) What is the utilization of each machine in the cell? [16]

Part Operation time (min)Machine 1 Machine 2 Machine 3

A 4 15 10B 15 18 7C 26 20 15D 15 20 10E 8 16 10

1 of 2


7. A flexible machining system consists of two machining workstations and a load/unloadstation. Station 1 is the load/unload station. Station 2 performs milling operationsand consists of two servers (two identical CNC milling machines). Station 3 hasone server that performs drilling (one CNC drill press). The stations are connectedby a part handling system that has four work carriers. The mean transport timeis 3.0 min. The FMS produces two parts, A and B. The part mix fractions andprocess routings for the two parts are presented in the table below. Determine,

(a) maximum production rate of the FMS,

(b) corresponding production rates of each product,

(c) utilization of each station and

(d) number of busy servers at each station. [16]

Part Part Mix Operation Description Station Process time (min)A 04. 1 Load 1 4

2 Mill 2 303 Drill 3 104 Unload 4 2

B 0.6 1 Load 1 42 Mill 2 403 Drill 3 154 Unload 1 2

8. How does Lean Manufacturing make a mass production system flexible? [16]

⋆ ⋆ ⋆ ⋆ ⋆

2 of 2






1. What are the three modeling modes offered by CAD/CAM systems? What do theydo? [16]

2. Prove that the multiplication of transformation matrices for the following sequenceof operations is commutative.

(a) Two successive rotations

(b) Two successive translations

(c) Two successive scalings. [16]

3. Given a point Q and a parametric curve in the Cartesian space, find the closestpoint P on the curve to Q. Hint: Find P such that (Q - P) is perpendicular to thetangent vector. [16]

4. Find the geometric modifiers available on your CAD/CAM system. What is theirsyntax? How do you use them? What is the default modifier? [16]

5. (a) What is meant by tool off set compensation? Discuss its importance.

(b) What are the characteristics of ATC? How do they differ from Turrets? [8+8]

6. (a) What factors must be considered while selecting a classification and codingsystem?

(b) Discuss the advantages and the limitations of OPITZ code system. [8+8]

7. Describe the following operational issues related to FMS.

(a) Scheduling and dispatching

(b) Machine loading. [8+8]

8. Discuss how Lean production differs from Job shop production system. [16]

⋆ ⋆ ⋆ ⋆ ⋆

1 of 1






1. CAD/CAM systems have one of the following orientations for MCS: XY planehorizontal or XY plane vertical. Sketch each system in 3D space. [16]

2. Calculate the transformed (rotation of 300) coordinates of the following. A rectangleof size 25 mm X 40 mm. [16]

3. Given a point Q and a parametric curve in the Cartesian space, find the closestpoint P on the curve to Q. Hint: Find P such that (Q - P) is perpendicular to thetangent vector. [16]

4. Three point sets in E2 define three valid polygonal solids S1, S2 and S3. The threesolids are bounded by three boundary sets bS 1, bS2 and bS3 given by their comerpoints as: bS1 := (2, 2), (5, 2), (5, 5), (2, 5), bS2 = (3, 3), (7, 3), (7, 6), (3, 6) andbS3 = (4, 1), (6, 1), (6, 4), (4, 4). Find S1 ∪ S2 ∪ S3, S1 ∩ S2 ∩ S3 and S1 - S2 - S3.

[16]

5. (a) Discuss

i. Geometric statements and

ii. Cutter motion statements used in APT.

(b) Name any two CAM packages. How do you generate NC part program in suchpackages? [8+8]

6. Discuss the advantages of GT in Manufacturing. [16]

7. Describe the following operational issues related to FMS.

(a) Scheduling and dispatching

(b) Machine loading. [8+8]

8. Describe hardware configuration of CIM with the help of a sketch. [16]

⋆ ⋆ ⋆ ⋆ ⋆

1 of 1

Code No: M0202/R05 Set No. 1

IV B.Tech I Semester Supplementary Examinations, Nov 2011POWER SYSTEM ANALYSIS

(Electrical & Electronic Engineering)Time: 3 hours Max Marks: 80

Answer any FIVE QuestionsAll Questions carry equal marks

? ? ? ? ?

1. For the given network shown in figure 1d connections form:

(a) Graph

(b) Tree

(c) Co-tree

(d) Cut-set. [16]

Figure 1d

2. Form the Zbus for the given network connections: [16]

Self MutualBus code (element) Impedence Bus code Impedence

1-2 (1) 0.61-3 0.5 1-2 (1) 0.13-4 0.5

1-2 (2) 0.4 1-2 (1) 0.22-4 0.2

3. Explain briefly the method of dealing with voltage controlled buses in load flowstudies. Explain with G-S method. [16]

4. Explain step-by-step algorithm of N-R (Polar form) algorithm including P-V buses.[16]

5. (a) What are the advantages of p.u system.

1 of 2


(b) For the network shown in figure 5b draw p.u impedance diagram. [10+6]

Figure 5b

6. (a) The voltages across a 3 phase unbalanced load are Vab = 300 V6 0; Vbc = 3006 -900; Vca = 800 6 1430 respectively. Determine the sequence components ofvoltages.

(b) Symmetrical components of unbalanced 3 phase currents are I0 = 3 6 -300; I1= 5 6 900; and I2 = 4 6 300. Obtain original unbalanced phasors. [8+8]

7. A 50 Hz synchronous generator with H = 2.5 MJ / MVA supplies power to infinitebus as shown in figure 7. Derive an expression for power delivered to infinite busand plot power angle curve. [16]

Figure 7

8. (a) Explain the methods of improving transient stability.

(b) A 50 Hz synchronous generator with inertia constant H = 4 MT/MVA and x′d

equal to 0.15 pu feeds 1.0 pu power to an infinite bus at 0.8 pf lagging. Via anetwork with an equivalent reactance of 0.3 pu. A 3 phase fault is sustainedfor 100 milli seconds at the terminals. Plot swing curve through t = 0.25 secs.

[8+8]

? ? ? ? ?

2 of 2





? ? ? ? ?

1. Form the network matrices Zloop using non-singular transformation for the networkconnections: [16]

element p-r1 1-2 (1)2 1-2(2)3 1-34 2-45 3-5

SelfBus code Impedence

1-2 0.61-3 0.53-4 0.5

1-2(2) 0.42-4 0.2

MutualBus code Impedence

1-2(1) 0.11-2(1) 0.2

2. The bus impedance matrix for the network connection is found to be (G-Ground):There is a line outage and the line from bus 1 to 2 is removed. Using the methodof building algorithm determine the new bus impedance matrix. [16]

Element Bus code impedance1 1-G j0.22 1-2 j0.53 1-3 j0.24 1-4 j0.35 2-G j0.36 2-4 j0.67 3-4 j0.1

1 2 3 41 0.150 0.075 0.140 0.135

Zbus = 2 0.075 0.1875 0.090 0.09753 0.140 0.090 0.2533 0.2104 0.135 0.0975 0.210 0.2475

3. Why direct simulation of load flow is not possible? and mention data required forload flow solution? [16]

4. With the help of flow chart explain the computational procedure used for load flowusing Fast Decoupled method. [16]

1 of 2


5. (a) Prove that Base impedance =KV 2

LL(Base)

MVA3−φ(Base)

(b) Obtain pu impedance diagram of the power system of figure 5b. Choose basequantities in generagor circuit.

Generator: 20 MVA, 11 KV, X ′′= 0.1 puTransformer: 25 MVA, 11/33 KV, X = 0.1 puLoad: 10 MVA, 33 KV, 0.8 pf lag. [16]

Figure 5b

6. (a) Pabc is 3 phase power in a circuit and P012 is power in the same circuit in termsof symmetrical components. Show that abc = 012.

(b) The line currents in a 3 phase supply to an un balanced load are respectivelyIa = 10 + j20; Ib = 12 - j10; Ic = -3 - j5 Amp. phase sequence is abc. Determinethe sequence components of currents. [8+8]

7. A 275 KV transmission line has following line constants.A = 0.85 6 50, B = 200 6 750

The line delivers 150 MW with |VS| = |VR| = 275KV . Determine synchronizingpower coefficient. [16]

8. A 50 Hz, 500 MVA, 400 KV generator (including transformer) is connected to a400 KV infinite bus bar through on inter connector. The generator has H = 2.5MJ/MVA. Voltage behind transient reactance 420 KV and supplies 460 MW. Thetransfer reactance between generator and bus bar under various conditions arePrefault = 0.5 pu; During fault = 1.0 pu; Post fault = 0.75 pu.Calculate swing curve using ∆T = 0.05 sec, with fault cleared at 0.1 secs. Theperiod of study is 0.2 secs. [16]

? ? ? ? ?

2 of 2





? ? ? ? ?


element p-r1 1-2 (1)2 1-2(2)3 1-34 2-45 3-5


1-2 0.61-3 0.53-4 0.5

1-2(2) 0.42-4 0.2


1-2(1) 0.11-2(1) 0.2

2. Explain modification of the bus impedance matrix for changes in the network.[16]

3. For the power system shown in fig. obtain the voltage at bus 2 at the end of thefirst iteration use G-S method. Line impedances are shown in fig bus 1 is the slackbus with voltage at 1 6 0 Pu. [16]

P2 + jQ2 = (-5.96+j1.46)Pu and |V3| =1.02 Pu. Assume V(0)3 = 1.02 6 00 and V

(0)2

= 1 6 00

1 2 3(0.04+j0.06)Pu (0.02+j0.03)Pu

4. Derive N-R (Polar form) equations and N-R (Rectangular form) equations andexplain difference between these methods. [16]

5. (a) A 3 phase fault through fault impedance Zf = 0.08 occurs at point F on thesystem shown in figure 5. The system is operating at noload and rated voltage.Determine bus voltages and line currents during the fault.

(b) State the assumptions made in short circuit analysis. [10+6]

1 of 2


Figure 5



7. A generator supplies 1.0 pu power to an infinite bus as shown in figure 7. Theterminal voltage and infinite bus voltage are 1.0 pu. All the reactances are on acommon base. Determine steady state stability limit: [16]

(a) when both lines are in

(b) when one line is switched off.

Figure 7

8. (a) Derive swing equation of a single machine connected to infinite bus.

(b) A synchronous generator is feeding 250 MW to a 50 Hz large network over adouble circuit line. The maximum steady state power that can be transmittedover line with both circuits in operation is 500 MW and is 350 MW with anyone of the circuit. A solid 3 phase fault at network-end of one the line causesit to trip. Find critical clearing angle before which circuit breakers have totrip. [8+8]

? ? ? ? ?

2 of 2





? ? ? ? ?


element p-r1 1-2 (1)2 1-2(2)3 1-34 2-45 3-5


1-2 0.61-3 0.53-4 0.5

1-2(2) 0.42-4 0.2


1-2(1) 0.11-2(1) 0.2

2. The bus impedance matrix for the network connection is found to be (G-Ground):There is a line outage and the line from bus 1 to 2 is removed. Using the methodof building algorithm determine the new bus impedance matrix. [16]

Element Bus code impedance1 1-G j0.22 1-2 j0.53 1-3 j0.24 1-4 j0.35 2-G j0.36 2-4 j0.67 3-4 j0.1

1 2 3 41 0.150 0.075 0.140 0.135

Zbus = 2 0.075 0.1875 0.090 0.09753 0.140 0.090 0.2533 0.2104 0.135 0.0975 0.210 0.2475

3. The converged load flow solution is available how do you determine the slack buscomplex power injection and system total loss? [16]

4. With the help of flow chart explain the computational procedure used for load flowusing Fast Decoupled method. [16]

1 of 2


5. (a) A 3 phase fault through fault impedance Zf = 0.08 occurs at point F on thesystem shown in figure 5. The system is operating at noload and rated voltage.Determine bus voltages and line currents during the fault.

(b) State the assumptions made in short circuit analysis. [10+6]

Figure 5



7. A 3 phase 50 Hz transmission line is 200 Km long. The line parameters are r = 0.1ohm /Km; x = 0.25 ohm/km; y = 3 × 10−6 mho / Km. The line is represented bynominal π model. If |VS| = |VR| = 200KV determine steady state stability limit.

[16]

8. A 50 Hz, 500 MVA, 400 KV generator (including transformer) is connected to a400 KV infinite bus bar through on inter connector. The generator has H = 2.5MJ/MVA. Voltage behind transient reactance 420 KV and supplies 460 MW. Thetransfer reactance between generator and bus bar under various conditions arePrefault = 0.5 pu; During fault = 1.0 pu; Post fault = 0.75 pu.Calculate swing curve using ∆T = 0.05 sec, with fault cleared at 0.1 secs. Theperiod of study is 0.2 secs. [16]

? ? ? ? ?

2 of 2


IV B.Tech I Semester Supplementary Examinations, November 2011OPTICAL COMMUNICATIONS

( Common to Electronics & Communication Engineering and Electronics &Telematics)



1. (a) Derive the wave equation for a step index fiber.

(b) Calculate the critical angle, maximum entrance angle and NA for a step indexfiber having a core index of 1.60 and a cladding index of 1.49. Derive theexpressions used. [8+8]

2. (a) A single mode step index fiber with a core refractive index of 1.49 has a criticalbending radius of 10.4 mm when illuminated with light at a wavelength of 1.3µm. If the cut off wavelength for the fiber is 1.15 µm, calculate the relativerefractive index difference.

(b) Compare stimulated Brillouin and stimulated Raman scattering in opticalfiber. [8+8]

3. (a) Explain the theory of material dispersion and find an expression for RMSmaterial dispersion.

(b) A single mode step index fiber has a zero dispersion wavelength of 1.29 µmand exhibits total first order dispersion of 3.5 ps m−1 km−1 at a wavelength of1.32 µm. Determine the total first order dispersion in the fiber at a wavelengthof 1.54 µm. [8+8]

4. (a) List out the advantages of semiconductor laser diodes over LED, when usedfor fiber transmission.

(b) An LED is made with gallium arsenide dopped with aluminium and has anenergy band gap of 1.55 eV. What is its dominant emission wavelength.[8+8]

5. (a) With the help of neat diagrams describe lens coupling mechanisms to improvecoupling efficiency from a fiber optic source.

(b) Differentiate between Lambertian and monochromatic optical sources in termsof power coupling into a single mode fiber.

(c) What is equilibrium numerical aperture? Explain the significance of equilib-rium numerical aperture on source to fiber power coupling. [6+5+5]

6. (a) Describe important specifications of a semiconductor photo diode to be suit-able for fiber optic communications.

(b) Compute the range of quantum efficiency of an InGaAs PIN diode in thewavelength range between 1200 nm and 1600 nm if the responsivity of thediode is specified to be more than 0.6 A/W in the required wavelength region.

1 of 2


Use the necessary physical constants listed. [8+8]Speed of light in vacuum =3 × 108 m/sElectron charge =1.602 × 10−19 CPlanck’s constant =6.6256 × 10−34 J-SBoltzman’s constant =1.38 × 10−23 J/KBand gap energy of InGaAs = 0.73 eV at 300K

7. Write a short note on the following:

(a) System considerations in the design of a fiber optic link.

(b) System rise time calculation with the help of an example. [8+8]

8. (a) How can the maximum achievable transmission distance with a set of activeand passive components in an optical link be calculated? Explain with thehelp of necessary transmission curves.

(b) Describe eye patterns analysis for assessing the performance of a digital fiberoptic link. Is it possible to estimate BER also from eye patterns? [8+8]

⋆ ⋆ ⋆ ⋆ ⋆

2 of 2






1. (a) What are the different types of optical fibers, explain about them in detailwith the necessary figures, graphs and equations?

(b) An optical fiber with core and cladding refractive indices as 1.49 and 1.48respectively is immersed in a fluid. Determine the refractive index of this fluidif the maximum acceptance angle of the immersed fiber is 880. Comment onthe result. [8+8]

2. (a) The mean optical power launched in to an optical fiber link is 1.5 mw and thefiber has an attenuation of 0.5 dB km−1. Determine the maximum possible linklength without repeaters (assuming loss less connectors) when the minimummean optical power level required at the detector is 2 µw.

(b) Briefly describe the following linear scattering losses in optical fiber.

i. Rayleigh scattering

ii. Mie scattering. [8+8]

3. (a) Derive the expression for the pulse dispersion in a parabolic index mediumand in a planar step index wave guide.

(b) For a fiber, material dispersion parameter is 58.8 ps/ nm/ km. The relativespectral width δλ/λ of the source is 0.0012 at the wavelength of 850 nm.Calculate the RMS pulse broadening per km. [8+8]

4. (a) Draw the driving circuit laser transmitter and explain its operation.

(b) A Ga As laser emitting at 800 nm has a 400 µm long cavity with a refractiveindex n = 3.6. If the gain of exceeds the total loss αt throughout the range750 nm < λ < 850 nm, how many modes will exist in the laser, also find thefrequency separation of the modes. [8+8]

5. Write short notes on the following:

(a) Power coupling from a vertical Cavity Surface Emitting Laser (VCSEL) diodeto a single mode fiber.

(b) Radiation patterns in axial and vertical planes from surface emitting LED andedge emitting LED. [8+8]

6. (a) Describe important specifications of a semiconductor photo diode to be suit-able for fiber optic communications.

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(b) Compute the range of quantum efficiency of an InGaAs PIN diode in thewavelength range between 1200 nm and 1600 nm if the responsivity of thediode is specified to be more than 0.6 A/W in the required wavelength region.Use the necessary physical constants listed. [8+8]Speed of light in vacuum =3 × 108 m/sElectron charge =1.602 × 10−19 CPlanck’s constant =6.6256 × 10−34 J-SBoltzman’s constant =1.38 × 10−23 J/KBand gap energy of InGaAs = 0.73 eV at 300K

7. (a) Describe a method to carryout rise time budget analysis for a fiber optic link

(b) Explain the procedure to determine the maximum allowable RZ and NRZ datarates from rise time budget analysis.

(c) Explain the effect of mode mixing factor, q, on modal dispersion induced risetime. [8+4+4]

8. (a) How is excess mode filling during launching of optical power compensatedfor stabilized measurement of attenuation in optical fibers? Suggest possiblemethods.

(b) With at least 4 types of line codes, explain the improvement in quality oftransmission of signals in optical fibers. [8+8]

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1. (a) Briefly explain about the optical fiber construction details and show a figure fortransmission of light rays and discuss about the refractive index distributionwith a graph.

(b) A fiber with parameters n1 = 1.46, n2 = 1.455 and a = 3 µm has to be used assingle mode fiber in a communication system. Determine a suitable operatingwavelength. [8+8]

2. (a) Describe the radiative losses in fibers resulting in absorption.

(b) Explain the mechanisms of dispersion of signals in optical fibers. [8+8]

3. (a) Calculate the insertion loss of the connector when the power in the fiber is100 µw and the output power after the connector is 80 µw.

(b) A multimode graded index fiber exhibits the pulse broadening of 0.2 µs overa distance of 15 Km. Estimate:

i. Optimum bandwidth of fiber

ii. Dispersion per unit length

iii. Bandwidth length product. [8+8]

4. Explain the modulation capability of the laser diode and its temperature effects.How to compensate for variations in temperature? [16]

5. (a) Describe various mechanisms usable to increase power coupling from an LEDinto a single mode fiber. Discuss the intricacies involved.

(b) An LED with circular emitting region of radius 200 µm and an axial radianceof 60 W / cm2- Sr at 100mA drive current is coupled into a step index fiberof 50µm radius and 0.24 numerical aperture.

i. Compute the power coupled into this step index fiber.

ii. Calculate the power coupled from the source specified about into a parabolicindex graded-index fiber of same size as the step index fiber with n1=1.485and ∆ = 0.01. [6+5+5]

6. (a) Differentiate between the photodiode parameters, ’quantum limit’ and ’darkcurrent’.

(b) The quantum efficiency of an In GaAs PIN diode is 80% in the wavelengthrange between 1300 nm and 1600 nm. Compute the range of responsivity ofthe PIN diode in the specified wavelength range. [8+8]

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8. (a) How can the maximum achievable transmission distance with a set of activeand passive components in an optical link be calculated? Explain with thehelp of necessary transmission curves.

(b) Describe eye patterns analysis for assessing the performance of a digital fiberoptic link. Is it possible to estimate BER also from eye patterns? [8+8]

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1. (a) Draw the block schematic of a general communication system and explain thefunctions of each block.

(b) Discuss briefly about the leaky modes and mode coupling losses in the fiberoptic communication. [8+8]

2. (a) Explain the core and cladding losses in an optical fiber and derive the expres-sion for those losses..

(b) Discuss different scattering losses in SiO2 fiber at various operating wave-lengths in detail. [8+8]

3. (a) Write notes on “dispersion shifted fiber and dispersion compensating fiber”.

(b) Explain in detail about the refractive index profile dispersion and dispersionVs bandwidth of the optical fiber. [8+8]

4. (a) A single mode fiber has the following parameters normalized frequency (V)=2.40,core refractive index (n1) = 1.46, core diameter (2a) = 8 µm, numerical aper-ture(NA)=0.1. Estimate the total insertion loss of a fiber joint with a lateralmisalignment of 1 mm and an angular misalignment of 10.

(b) Explain the principle of operation of injected laser diode with a neat diagrams.[8+8]

5. (a) With the help of neat diagrams describe lens coupling mechanisms to improvecoupling efficiency from a fiber optic source.

(b) Differentiate between Lambertian and monochromatic optical sources in termsof power coupling into a single mode fiber.

(c) What is equilibrium numerical aperture? Explain the significance of equilib-rium numerical aperture on source to fiber power coupling. [6+5+5]

6. (a) List out the materials used and the desired features of a photo diode forusability in fiber optic links.

(b) Derive an expression for total mean-square noise signal in a photo detectorand hence the Signal-to-Noise Ratio at the output of a receiver. [8+8]



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8. (a) Is it possible to establish Bi-directional wavelength division multiplexed opticalcommunication link? Justify your answer with relevant equations, diagramsnumerical values and description.

(b) How is the maximum achievable data rate estimated from dispersion measure-ments for RZ and NRZ formats of data?

(c) List out the differences between time domain and frequency domain approachesin measurements of inter modal dispersion. [5+6+5]

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FEM

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