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# Electrical Engineering

### Controllable and observable systems

A dc motor has a transfer function (see attachment). Determine whether the system is controllable or observable.

### Magnetically suspended steel ball

A magnetically suspended steel ball can be described by the linear equation as shown in the attachment. The state variables are x1 = position, and x2 = velocity, and both are measurable. Select a feedback format so that the system is critically damped and the settling time (2% criterion) is 2 seconds. Solve for k1 and k2.

### Z-Transforms for Discrete-Time Signals

1. Compute the s-Transform for the discrete-time signal x[n] = (0.5)(^n)nu[n]. 2. Compute the z-Transform for the discrete-time signal x[n] = (0.25)(^-n)u[n-2]. 3. For the discrete-time signal x[n] with the z-Transform X(z) = z/(8z^2 - 2z - 1) find the z-Transofmr, V(z) for the signal v[n] = e^(3n)x[n].

### Frequency Response and Response Curve

The frequency response for a process of the for G(s)= (Ks) / ((s + a)(s^2 + 20s + 100)) is shown in the attachment. Determine K and a by examining the frequency response curve. See the attached file.

### Full Wave Center Tap Bridge Rectifier

In the attached image, how is VDC across the load resistor found? The practice test has an answer of 28.24 ignoring the ripple voltage. VDC across the resister is Vout right? So, Vsecondary - the voltage drop in the diode = Vout = VDC So, if the secondary winding has 40voltage - .7V drop in the top resistor, that's 39.3V

### Digital signal processing problem

The problem(2-61) is from the third edition of digital signal processing(proakis+manolakis) 2-61 an audio signal s(t)generated by a loud speaker is reflected at two different walls with reflection coefficients r1 and r2. the signal x(t) recorded by amicrophone close to the loud speaker, after sampling is;

### Input/Output Difference Equations

Please see the attached file for full problem description. These are multiple-choice questions; I only need the correct answers for the three equations Find the input/output differential equations for the circuit above when: 1) y(t) = vR(t) 2) y(t) = i(t) 3) y(t) = vC(t)

### How many T-1 lines are needed to make up one OC12 line? Need to see the calculated out to understand this

How many T-1 lines are needed to make up one OC12 line? Need to see the calculated out to understand this

### Time division multiplexing and Frequency division multiplexing

What's the difference between Time division multiplexing and Frequency division multiplexing

### Common emitter amplifer

The parameters of the transistor are Beta=100 and Va=100V. Find the DC voltages at the base and emittter terminals. See attachment for circuit.

### Bias Stable Transisor Design Problem

Please help with the following problem. The DC load line and Q point of the circuit are shown next to the circuit. For the transistor, Beta=120. Find Re, R1, and R2 such that the circuit is bias stable. Is it valid for me to do a KVL around the C-E loop using ic=4.8ma and vce=6v (ie=ic (b+1/b)) to find RE? And then get

### Average current and average voltage

A full-wave bridge rectifier circuit with a 1-kohms load operates from a 120-V (rms) 60-Hz household supply through a 10-to-1 step-down transformer having a single secondary winding. It uses four diodes, each of which can be modeled to have a 0.7-V drop for any current. What is the fraction of a cycle that each diode conducts? W

### Signal Processing

See attachment for better symbol representation. 1. Find and sketch the spectrum of the following signal. x(t) = cos(t) + cos (2t)*cos(3t) (Express the trigonometric functions in terms of complex exponentials using one of Euler's formulae, then perform the arithmetic (multiplication) and then express x(t) in terms of sep

### Use algebraic manipulation to find the expression.

Use algebraic manipulation to find the expression f(x1, x2, x3) = SUM m(1,2,3,4,5,6,7). A. f = x1 + x2 + x3 B. f = x1x2x3 C. f = x1x3 + x2 D. f = x2 + xbar1 + x3

### Shannon's expansion to derive an implementation of a function

For the function, use Shannon's expansion to derive an implementation using a 2-to-1 multiplexer and any other necessary gates. Please see the attached MS Word file for the full function.

### Finite State Machine

Finite State Machine A finite state machine (FSM) is either deterministic or non-deterministic. A deterministic FSM (DFSM) is a FSM with at most one transition for each symbol and state. A non-deterministic FSM (NDFSM) is a FSM whose transition function maps input symbols and states to a (possibly empty) set of next states. T

Plot the frequency response and the poles and zeroes in each case. Use a sampling frequency of one rad/sec. Compare the filter frequency responses. (See attachment for full question).

### Subnets

An organization owns the network 200.1.1.0/24 and wants to form subnets for 4 departments, with hosts as follows: A 72 hosts B 35 hosts C 20 hosts D 18 hosts There are 145 hosts in all. a. Give a possible arrangement of subnet masks to make this possible. b. Suggest what the organization might do if department D

### Transmission Delay

A two-port bridge connects on the end of a cable of length X m. to the end of a similar cable of length 3x/2 m. Hosts are attached at various points on the cable system, which operates as a shared-access LAN implementing the CSMA/CD protocol with a minimum frame length of 512 bits. The bridge imparts a delay in forwarding frame

Suppose a router has built up the routing table shown in Table below. The router can deliver packets directly over interfaces 0 and 1, or it can forward packets to routers R2, R3, or R4. Describe what the router does with a packet addressed to each of the following destinations (see Attachment)

### Determine the peak-to-peak ripple current

An Rl load as shown in figure below is controlled by a chopper. If load resistance R=0.25 ohms, inductance L=20 mH, supply voltage Vs=600V, battery voltage E=150V, and chopping frequency F=250 Hz, determine the peak-to-peak ripple current (delta I). See Attached File.

### RMS current ratings of a diode

The waveforms of the current flowing through a diode are shown in the figure below. Determine the RMS current ratings of the diode.

### Derive the expression for the small-signal voltage gain.

The common-emitter circuit has an emitter bypass capacitor. (a) Derive the expression for the small-signal voltage gain Av(s)=Vo(s)/Vi(s). Write the expression in a form similar to that of equation (Av=(-Gm*Rpi*Rc)(Rs+rpi+(1+Beta)Re)*((1+s*taua)/(1+s*taub)). (b) What are the expressions for taua and taub? The circuit is

### Give a brief Hspice Netlist example that explains how to read and understand .hsp files.

Often Netlist is generated by programs such as Cadence. However, on the rare occasions when one has to look at Hspice netlist, one should not be at a complete loss. Give a brief Hspice Netlist example that explains how to read and understand .hsp files.

### Determine, in general, what type of load impedances can be matched using such a circuit.

In the circuit shown (in the attachment) a ZL = 200 + j 100 Ohm load is to be matched to a 40 Ohm line, using a length, l, of lossless transmission line of characteristic impedance, Z1. Find l and Z1. Determine, in general, what type of load impedances can be matched using such a circuit.

### Diode DC Models: calculating current and diode parameters

1) Two identical diodes are connected in series with 100 ohms and a 2 V battery such that each diode is forward biased. Let Io = 10fA; n = 1, T = 25 degrees C. Calculate the loop current if (a) ideal diodes are assumed; (b) VD = 0.6 V for each diode; (c) each diode is represented by a piecewise-linear model that is exact at ID

### Determine the Thevenin equivalent resistance (Rt) of the circuit within the box.

A resistor, R, was connected to a circuit box as shown. The voltage, V, was measured. The resistor was changed and the voltage was measured again. The results are shown in the table. Determine the Thevenin equivalent resistance (Rt) of the circuit within the box. See attached file for full problem description.

### Verifying Voltage Measurement

The circuit shown in the attached figure was built in the laboratory and V0 was measured to be 6.25V. Verify this measurement using the voltage divider principle, whether measured result is consistent with the figure.

### Current through the inductor

A security alarm for an office building door is modeled by the circuit as shown in the attachment. The switch represents the door interlock, and V is the alarm indicator voltage. Find the current through the inductor, iL(t), for t>0. The switch has been closed for a long time at t=0.

### Drawing a Ladder Diagram for a PLC Program

Draw the ladder diagram for the following PLC program. A batch process which involves filling a tank with liquid, mixing the liquid and draining the tank, is automated with a PLC. The specific sequence of events is as follows: When the start push button is pressed, a fill valve V1, opens and lets a liquid into the tank unt