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Friday, 6 December 2013

Industrial automation and robotics-model question paper for B.E/B.Tech/M.E/M.Tech


1(a) Differentiate between absolute and relative humidity. (4 Marks)
(b) Write short notes on application of hydraulics in automation. (4 Marks)
(c) Draw a neat sketch of pneumatic system and explain its components. (6 Marks)
(d) With the help of neat sketch, explain the working of vane pump. (6 Marks)
2(a) What is FRL unit in pneumatic systems? (4 Marks)
(b) Differentiate between dead weight and spring-loaded accumulators. (6 Marks)
(c) List down the reasons for using filter in hydraulics and pneumatics. (4 Marks)
(d) With the aid of sketches, explain the constructional features of a hydraulic cylinder. (6 Marks)
3(a) Sketch a shuttle valve and explain the working. (6 Marks)
(b) What are servo valves? Explain the construction and working of various types of servo valves with the help of neat sketches. (8 Marks)
(c) Explain cracking pressure and pressure override. (4 Marks)
(d) Differentiate between spool and seat valves. (4 Marks)
4 (a) List the basic types of hydraulic circuits. (4 Marks)
(b) Differentiate between throttle in and throttle out speed control circuit in pneumatics with help of a neat sketch. (6 Marks)
(c) Draw pressure reduction circuit and explain its working. (6 Marks)
(d) Explain the function of quick exhaust valve with the help of a neat sketch. (4 Marks)
5 (a) Discuss the step-wise procedure for design of pneumatic logic circuit for give sequence of operation. Illustrate the procedure by taking any simple example. (8 Marks)
(b) Explain the importance of position step diagram. (4 Marks)
(c) What is Coanda effect? Describe with diagram. (4 Marks)
(d) Describe the working of any fluidic device. (4 Marks)
6 (a) Discuss the various types of sensors used for position or displacement measurement. (4 Marks)
(b) Write a short note on thermocouple. (4 Marks)
(c) Explain the architecture of a programmable logic controller with the help of a neat sketch. (8 Marks)
(d) Describe any one type of job rotating devices. (4 Marks)
7 (a) What is robotic joint? Distinguish between prismatic and revolute joints. (6 Marks)
(b) Classify robots based on their geometry. (4 Marks)
(c) Briefly explain the various components of an industrial robot. State the main function of each of the components. (6 Marks)
(d) How is robotic vision sensed? What are the component systems used in most common vision based applications? (4 Marks)
8(a) Differentiate between contact and noncontact sensors in robots with the help of examples. Describe the construction and working principle of one contact and one noncontact type of sensor. (8 Marks)
(b) Explain the working principle of an end effector with the help of neat sketch and give its important applications. (4 Marks)
(c) What is meant by teach pendant programming of robots? (4 Marks)
(d) Prepare list of any four industrial operations that can be performed by robot. (4 Marks)

Antenna theory and design- model question paper for B.E/B.Tech



1(a) Write a note on directivity and gain of antennas. (4 Marks)
(b) What is a monopole? (4 Marks)
(c) Small loop antennas have considerable ohmic resistance. Explain. Mention some applications of Small loop antennas. (8 Marks)
(d) A 2m long dipole made of 6.35 mm diameter aluminium is operated at 500 kHz. Assuming current is uniform and triangular, determine its radiation frequency. (4 Marks)
2 (a) What is an isotropic radiator? (4 Marks)
(b) What are HP and BWFN? Show that HP is roughly one half of the corresponding BWFN value for long, uniformly excited linear arrays. (6 Marks)
(c) What is a beam forming network? (4 Marks)
(d) An interferometer is constructed from five collinear half-wave dipoles spaced two wavelengths apart. Sketch the polar plot of the complete array pattern. (6 Marks)
3 (a) Construct the linear, polar plot of the pattern factor for a broadside cosine-tapered line source that is three wavelengths long. (8 Marks)
(b) What are straight wire diploes? (4 Marks)
(c) The simplistic beauty of the Yagi is revealed by lengthening the parasite. Explain. (4 Marks)
(d) Design an optimum directivity vee dipole to have a directivity of 6 dB. (4 Marks)
4 (a) Differentiate between normal mode helix antenna and axial mode helix antenna. (6 Marks)
(b) A sinuous antenna is more complicated than the spiral antenna. Explain why? (4 Marks)
(c) Derive optimum pyramidal horn design equation. (6 Marks)
(d) Show that the directivity-beamwidth product for a uniform phase rectangular aperture with cosine amplitude taper in the H-plane and uniform amplitude in the E-plane is 35230 square degrees. (4 Marks)
5 (a) Explain Woodward-Lawson sampling method. (6 Marks)
(b) Explain Dolph-Chebyshev linear array method of antenna synthesis. (6 Marks)
(c) What is radar equation? Define radar cross section. (4 Marks)
(d) Calculate the antenna factor of a matched antenna operating at 30 MHz with a gain of 3 dB and terminated with a 50 Ω resistor. (4 Marks)
6 (a) Derive Pocklington’s integral equation. (8 Marks)
(b) Explain why delta gap model is known as slice generator. (4 Marks)
(c) What are compressed matrices? (4 Marks)
(d) Sketch a wire grid model for a square plate 1λ1λ. If pulse expansion functions are to be used, how many unknowns will your model have? (4 Marks)
7 (a) What is FD-TD approach? Explain with the help of a flowchart. (8 Marks)
(b) Write a detailed note on Vivaldi slotline array. (8 Marks)
(c) Can numerical dispersion occur in a non-dispersive medium? (4 Marks)
8 (a) Explain the postulates of Keller’s theory. (4 Marks)
(b) Explain the PTD formulation for surfaces with perfectly cutting edges. (6 Marks)
(c) Using physical optics, show that the radar cross section of a flat rectangular plate at normal incidence is σ = 4π (A22) where A is the area of the plate. (6 Marks)
(d) Write a note on the importance of GTD method in antenna and scattering problems. (4 Marks)

Op-amps and linear integrated circuits- model question paper for B.E/B.Tech



1(a) How do multiple lead or lag networks interact to form an overall system response? (4 Marks)
(b) Mention the advantages of using an active load. (4 Marks)
(c)What is a mask and how is it used in the construction of IC op amps? What are the advantages of monolithic IC construction? (8 Marks)
(d) A noninverting amplifier has a midband voltage gain of 18 dB and a single-lag network at 200 kHz. What are the gain and phase values at 30 kHz, 200 kHz and 1 MHz? (4 Marks)
2(a) Explain the term sacrifice factor. (4 Marks)
(b) Explain the terms virtual ground and floating load. (6 Marks)
(c) What form pof feedback is used for the inverting current amplifier? (4 Marks)
(d) Design a simple differential amplifier with an input impedance of 10 kΩ per leg and a voltage gain of 26 dB. (6 Marks)
3 (a) Mention the advantages and disadvantages of noncompensated op-amps. (6 Marks)
(b)  What is the cause for DC offset voltage? (4 Marks)
(c) Write a note on the effect of slew rate on pulse signals. (6 Marks)
(d) Determine the upper break frequency for a noninverting amplifier with a gain of 20 dB while using 741 op amp. (4 Marks)
4 (a) Explain how a Norton amplifier achieves input differencing. (6 Marks)
(b) Utilizing the LM3900, design an inverting amplifier with a gain of 12 dB, an input impedance of at least 100 kΩ, and a lower break frequency not greater than 25 Hz. (8 Marks)
(c) What is a Schmitt trigger? (4 Marks)
(d) Mention the advantages of active rectifiers against passive rectifiers. (4 Marks)
5 (a) What is the function of a pass transistor? (6 Marks)
(b) Explain the term thermal resistance. (4 Marks)
(c) Explain the correlation between the output current demand and the pulse width modulator used in switching regulators. (6 Marks)
(d) Design a +12 V regulator using the LM 317. The output current capability should be atleast 900 mA. (4 Marks)
6 (a)What is the function of the capacitor in the basic integrator and differentiator? (4 Marks)
(b) Using a neat sketch, explain the operation of Wien bridge op amp oscillator. (8 Marks)
(c) Explain the difference between astable and monostable operation of a timer. (4 Marks)
(d) Assuming an accurate 50 kHz oscillator as a source, generate a stable 400 kHz square wave using a PLL. (4 Marks)
7 (a) What are the four main types of filters. (4 Marks)
(b) Explain the operation of adjustable bass equalizer. (6 Marks)
(c) Explain different filter alignment types. (6 Marks)
(d) A band-pass filter has upper and lower break frequencies of 9.5 kHz and 8 kHz. Determine the centre frequency and Q of the filter. (4 Marks)
8 (a) Explain the terms quantization and Nyquist frequency. (6 Marks)
(b) Differentiate between integral nonlinearity and differential nonlinearity. (6 Marks)
(c) What is the purpose of a track-and-hold amplifier? (4 Marks)
(d) A certain system uses a 12-bit word to represent the input signal. If the maximum peak-to-peak signal is set for 2 V, determine the resolution of the system and its dynamic range. (4 Marks)

Wednesday, 4 December 2013

Fiber-optic communication systems-Model question paper for B.E/B.Tech



1(a) Write a note on fiber birefringence. (4 Marks)
(b) Differentiate between stimulated Brillouin scattering and stimulated Raman scattering. (8 Marks)
(c) What is the necessity of cabling of fibers? (4 Marks)
(d) Assume that a digital communication system can be operated at a bit rate of up to 1% of the carrier frequency. How many audio channels at 64 kb/s can be transmitted over a microwave carrier at 5 GHz and an optical carrier at 1.55 mm. (4 Marks)
2 (a) Explain the double heterostructure geometry of Burrus type LED. (8 Marks)
(b) Write a note on vertical-cavity surface-emitting lasers. (4 Marks)
(c) Explain the terms extinction ratio and modulation bandwidth. (4 Marks)
(d) The threshold current of a semiconductor laser doubles when the operating temperature is increased by 500C. What is the characteristic temperature of the laser? (4 Marks)
3 (a) Explain the working of avalanche photodiodes. Mention some applications. (8 Marks)
(b)Explain in brief different noise mechanisms in an optical receiver. (4 Marks)
(c) Explain the term timing jitter. (4 Marks)
(d) Determine the responsivity of a p-i-n photodiode at 1.3 and 1.55mm if the quantum efficiency is 80%. Why is the photodiode more responsive at 1.55mm? (4 Marks)
4 (a) What are loss-limited lightwave systems and dispersion-limited lightwave systems. (6 Marks)
(b) Prove that for a Gaussian optical pulse, the rise time Tr and the 3-dB optical bandwidth Δf are related by Tr Δf = 0.316. (6 Marks)
(c)Write a note on prechirp technique. (4 Marks)
(d) What is the dispersion-limited transmission distance for a 1.55 mm lightwave system making use of direct modulation at 10 Gb/s? Assume that frequency chirping broadens the Gaussian-shape pulse spectrum by a factor of 6 from its transform-limited width. Use D=17 ps/(km-nm) for fiber dispersion. (4 Marks)
5 (a) Write a note on pulse amplification in semiconductor optical amplifiers. (4 Marks)
(b) Explain how stimulated Raman scattering is used in Raman amplifiers. (6 Marks)
(c) Write a note on distributed EDFAs. (6 Marks)
(d) The Lorentzian gain profile of an optical amplifier has a FWHM of 1 THz. Calculate the amplifier bandwidths when it is operated to provide 20- and 30-dB gain. Gain saturation is neglected. (4 Marks)
6 (a) What is wavelength division multiplexing? (4 Marks)
(b) Differentiate between direct-sequence encoding and spectral encoding. (6 Marks)
(c)Design an add-drop filter by using a single fiber coupler and two fiber gratings. (6 Marks)
(d) Explain how stimulated Raman scattering can cause crosstalk in multichannel lightwave systems. (4 Marks)
7 (a) What are dark solitons? (4 Marks)
(b) Explain lumped and distributed amplification schemes for compensation of fiber losses in soliton communication systems. (6 Marks)
(c) Write a note on system design issues in high speed soliton systems. (6 Marks)
(d) What is amplified spontaneous emission? (4 Marks)
8 (a) Explain homodyne and heterodyne detection techniques. (6 Marks)
(b) What are modulation formats? Draw ASK, PSK and FSK modulation formats for a specific bit pattern. (6 Marks)
(c)Draw Bit-error-rate curves for various modulation formats. (4 Marks)
(d) A 1.55 mm DFB laser is used for the FSK modulation at 100 MB/s with a tone spacing of 300 MHz. The modulation efficiency is 500 MHz/mA and the differential quantum efficiency equals 50% at the bias level of 3 mW. Estimate the power change associated with FSK by assuming that the two facets emit equal powers. (4 Marks)