Challenging Engineering Problems with Detailed Answers

Problem III (20pts): Signals, Systems, Fourier Transforms, and Duality Properties sinan) Given tvo sine-pulses, (t) = sinc(21) and x()=sine) with sinett) 1. (Apts) Sketch the time domain waveforms of these two sine-pulse signals and mark your axes 2 2. (4pts) Using FT property to find and sketch the frequency domain spectra of h(t) and c() as functions of Hertz frequency f = i.e. H(S)= ? vs. f and X(t) = ? vs. / in Hz, and mark your axes. 3. (6pts) Now, the steady-state response of a LTI system, y(t) is the convolution of two sinc-pulses, i.e. y()= x(1) h(t). Find and simplify the expression of y(t) = ? 4. (6pts) For a new LTI system with a switched choice of input and impulse response, say h(t) = sinc() and X(t) = sinc(21), what happens to the detailed expression of the output y(t) = ? in terms of its relationship to input x(1) = -sinc(21)? 2
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Given the following code, org ooh ; istart at program location 0000h MainProgram Movf numb1,0 addwf numb2,0 movwf answ goto $end ;place Ist number in w register ;add 2nd number store in w reg ;store result ;trap program (jump same line) ;end of source program 1. What is the status of the C and Z flag if the following Hex numbers are given under numb1 and num2: b. Numb1 =82 and numb2 =22 c. Numb1 =67 and numb2 =99 [3] 2. Draw the add routine flowchart. [4] 3. List four oscillator modes and give the frequency range for each mode [4] 4. Show by means of a diagram how a crystal can be connected to the PIC to ensure oscillation. Show typical values. [4] 5. Show by means of a diagram how an external (manual) reset switch can be connected to the PIC microcontroller. [3] 6. Show by means of a diagram how an RC circuit can be connected to the PIC to ensure oscillation. Also show the recommended resistor and capacitor value ranges. [3] 7. Explain under which conditions an external power-on reset circuit connected to the master clear (MCLR) pin of the PIC16F877A, will be required. [3] 8. Explain what the Brown-Out Reset protection circuit of the PIC16F877A microcontroller is used for and describe how it operates. [5]
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G (s): 10 (s +0) s(st) (s2+45+ 16) bode chart a) draw a b) Check stability of closed-loopsystem .
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for three phase bridge controlled rectifier, f i/p = 50 HZ1) Draw the load voltage and current.2) Draw the switching pulse sequence.3) Draw the i/p circuit for one phase.4) Drive the d.c and r.m.s values of load voltage.5) Discuss your graphs.6) find the o/p frequency.
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(a) Convert the hexadecimal number (FAFA.B)16 into decimal number. (4 marks) (b) Solve the following subtraction in 2s complement form and verify its decimal solution.01100101 11101000 (c) Boolean expression is given as: A + B[AC + (B + C)D](i) Simplify the expression into its simplest Sum-of-Product(SOP) form. (ii) Draw the logic diagram of the expression obtained in part (c)(i).(iii) Provide the Canonical Product-of-Sum(POS) form.(iv) Draw the logic diagram of the expression obtained in part (c)(iii).(4 marks)(6 marks) (3 marks) (4 marks) (4 marks)(Total: 25 marks)
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(b) A 3 phase 6 pole star connected induction machine operates from a 1G,0 V (phase voltage) and 60 Hz supply. Given the equivalent circuit parameters shown in Table Q4b, and assuming the friction and windage loss is negligible, calculate the following parameters when operating at a speed of 116G6 rpm: The slip. (ii) (iii) The mechanical power (W). The torque (Nm). (iv) The Input Power (W). (v) The no load current (A). D I don't Ale
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E. Refer to Figure 5. The single-phase "exact"-equivalent circuit of a practical transformer has the following equivalent circuit parameters: N p/N s=2400 V/240 V,R p=14.1,X p= 31.2,R s=78.5 m,X s=120.5 m,R C=156k,X M=172k. The load is a resistor with a value of R L=1.95. The source voltage is 240030 V. 26. Determine the Thevenin impedance "seen" by the source. 27. Determine the source current I I. 28. Determine the voltage E P. 29. Determine the voltage V L. 30. Determine the complex power delivered by the source. 31. Determine the RMS value of the transformer's magnetizing current. 32. Determine the core loss of the transformer. 33. Determine the copper losses of the transformer. 34. Determine the transformer's efficiency. 35 . Determine the transformer's voltage regulation using R Las the full load condition.
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You are asked to design a cyclic modulo-6 synchronous binary counter using J-K flip-flops. The counter starts at 0 and finishes at 5. (a) Construct the state diagram for the counter. (3 marks) (b) Construct the next-state table for the counter. (3 marks) (c) Construct the transition table for the J-K flip-flop. (3 marks) (d) Use K-map to determine the simplest logic functions for each stage of the counter. (9 marks) (e) Draw the logic circuit of the counter using J-K flip-flops and necessary logic gates. (7 marks) (Total: 25 marks)
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An X-Y setup on an oscilloscope is used to capture the in-phase and quadrature signals from a noisy communication system. x) Provide the following: What is the digital signaling technique being employed? What is the bandwidth requirement as compared to BPSK sending data at the same bit rate? What is the energy/bit requirement as compared to BPSK to ensure equivalent BER? y) Discuss the strategy for assigning bit patterns to each symbol that would ensure the overall BER is minimized. Illustrate this concept through assigning bit patterns to each symbol. H 1.00 m 100$ KOD TROV .
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1. a) Develop the equations for the CARRY terms of a 4-bit Look-Ahead-Carry Adder. (6 marks) b) (2 marks) Why is this structure unsuitable for a 16 bit adder ? Develop the structure for the circuit of one (4-bit) digit of a Binary Coded Decimal (BCD) Adder. c) (8 marks) d) When performing 4-bit conversion of Binary to BCD a shift and add 3 process is used if the current 4-bit BCD word is >4. i) Design the hardware necessary to perform this ii) Why is this different to the operation performed in c) above?
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Transfer function of a filter is given as, H(s) = 20s (s + 2)(s+200) i. Determine the filter's gain, cut-off frequency and type of frequency response. ii. Sketch the Bode plot magnitude of the filter.
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1 (a) Convert the hexadecimal number (FAFA.B)16 into decimal number. (4 marks) (b) Solve the following subtraction in 2's complement form and verify its decimal solution. 01100101 - 11101000 (4 marks) (c) Boolean expression is given as: A + B[AC + (B+C)D] (1) Simplify the expression into its simplest Sum-of-Product(SOP) form. (6 marks) (ii) Draw the logic diagram of the expression obtained in part (c)(i). (3 marks) (4 marks) (iii) Provide the Canonical Product-of-Sum(POS) form. (iv) Draw the logic diagram of the expression obtained in part (c)(ii).
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The FM signal you should generate is X3(t) = cos(211 x 105t + kf Scos(4t x 104t)). The value of depends on the modulation index, and the modulation index is 0.3What is the value of ? Provide the details of your calculation.
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The president of South Africa Mr.C.Ramaphosa and Minister of Energy Mr.Gwede Mantashe released a media statement that they have bought a compensator system to solve the loadsheding pandemic and the Eskom CEO tasked you to realize and implement the compensator G (s) to keep in order save your job and his job. G(s)= s+5.015s+0.5/s
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(b) Draw a diagram showing a star-connected source supplying a delta-connected load. Show clearly labelled phase voltages, line voltages, phase currents and line currents.
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1-What is the need of reactive power control in high power transmission system? 2-What is reactive power compensation in transmission line? 3-Describe the application of each of the introduced compensators in load compensation and line compensation. 4-Prove on each line in general that if |Es| = |Er| holds then Is = Ir. 5-A 600mil radial line with a nominal voltage of 400kv has a series reactance of 0.60 / mi and a capacitive parallel suspension of Sus / mi. Assuming that the voltage at the beginning of the line is equal to the nominal voltage, it is desirable: a) Calculate the voltage in the middle of the line in both the case of no load and full load condition. b) If a reactor with Km=1 is installed in the middle of the line, obtain the voltage in the middle of the line and the reactive power at the beginning of the line during no load and full load condition. (Reactive power calculation should be done only in full load condition.) 6- A 400 km, 138 kV, 60 Hz transmission line has the following distributed parameters:/= 0.106 2/km, x = 0.493 2/km, y=j3.36 x 10 S/km. Losses are neglected. IT (a) Compute the nominal equivalent circuit parameters and draw the circuit. Compute the corresponding ABCD parameters. (b) Find the surge impedance and surge impedance loading. (c) The line delivers 40 MW at 132 kV with a power factor of 0.95 lagging. Using the ABCD parameters, compute the sending end voltage, current and angle. Confirm using the nominal equivalent circuit, and the short line equivalent. (d) Draw the approximate voltage profile of this line for the following power delivered: (i) 0 MW, 20 MW, 50 MW, and surge impedance loading. Indicate the methods available to maintain the voltages within the range of 0.95 and 1.05.
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Consider a control loop of unity negative feedback, having a Pl controller feeding the following system's transfer function: 27 (as + 1), that has an open loop pole at -0.5. a) Determine the time constant of this system. (2 marks) b) Draw a diagram to represent the control system. (4 marks) c) Find the closed-loop transfer function. (4 marks) d) It is possible to eliminate the Zero (S term on the numerator of the closed loop transfer function). 1. First draw a newly configured block diagram to show how this is possible. (4 marks) II. Calculate the new transfer function to prove that your configuration does indeed eliminate the zero term. (4 marks) e) Let us assume a specification that includes a step-response overshoot of 10.53% and a rise time of 2.5 seconds. Find the I-P controller's gain values required to get this desired response.
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6 (a) Briefly describe the major difference between HEC and CLP regarding the connection from the transformer room to the main Low Voltage Switch- room. (2 marks) (b) What type of premises require rising main? (2 marks) (c) Electrical load in a building is mainly classified into any one of the three categories. The categories are (1) tenant load, (2) non-essential landlord load or (3) essential landlord load. State any ONE essential landlord load. (2 marks) (d) State any THREE parameters that can be used as a measure of the quality of services of a lift system. (3 marks) (e) List any ONE main type of incoming supply arrangement. (2 marks) (f) In practice, a group of electrical loads is variably connected to an emergency generator. The need for the simultaneous starting of the whole group of loads, particularly under full-load conditions, should be carefully assessed. In the case of motor-loads such simultaneous starting will require an emergency generator with a large kVA rating. Smaller the capacity of an emergency generator results in lower the cost. Suggest a method to reduce the kVA rating of an emergency generator with reasons.
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2. A 600 kVA, 380 V (generated emf), three-phase, star-connected diesel generator with internal reactance j0.03 2, is connected to a load with power factor 0.9 lagging. Determine: (a) the current of the generator under full load condition; and (3 marks) (b) the terminal line voltage of the generator under full load condition.
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Sub Principles of Communication7. What are uniform quantization and non-uniform quantization?
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A load impedance Zz = 25 + 130 is to be matched to a 50 2 line using an L-section matching networks at the frequency f=1 GHz. Find two designs using smith chart (also plot the resulting circuits). Verify that the matching is achieved for both designs. List the drawbacks of matching using L network.
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For a single-phase half-bridge inverter feeding RL load, derive an expression for output current. Also, determine the maximum and minimum values of the load current.
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Within the Discussion Board area, write 400-600 words that respond to the following questions with your thoughts, ideas, and comments. This will be the foundation for future discussions by your classmates. Be substantive and clear, and use examples to reinforce your ideas. Describe in detail the typical components that make up a microcontroller, including their roles, responsibilities and interaction with each other and the outside world. Be specific.
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Training requirements exist at different levels in the context of Environmental Management Systems. Name any two types of the training.
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