Circuitry

post has three assignments

1. In a p+np bipolar transistor circuit, grounded base circuit, a=0.99. The input circuit has a battery voltage of 1 V. Assume the input diode turns on at 0.6V(i.e. no IE until 0.6V, after that the diode current increases vertically without resistance).The series resistance in the input circuit is 100 ohm. The output circuit has a battery voltage of 40 V, and a load resistance in the output is 1k ohm.
Draw the dc Q conditions for both input and output. What is the DC Q point current and voltage in the output collector-base circuit? Draw a load line curve for the input and output. Show the intersection points for both.
2. In the above transistor, if Wb=1 micrometer, and the doping in the base is 2E17/cm3, and base and collector are equally doped, at what battery voltage in the CB circuit will the device break down? The Avalanche field is 5E5 V/cm.
3. In the transistor of #2, if I reduce the base and collector doping to 1E16/cm3, at what battery voltage in the CB circuit will the transistor break down?
4. In problem 1, now I overdrive the transistor by reducing series resistance in the inputcircuit. [That drives more current in the input and therefore in the output circuit]. Assume that saturation occurs when Vcb flips sign and become +0 .4V. What must the new series resistance in the input circuit be to achieve this? Assume that until then, a=0.99.
5. MOSFET amplifier. n channel. VT=1V. VGS=3 V. Z/L=40. Mobility=500 cm2/V-s. Cox=3.45E-7 F/cm2. Battery voltage in the output circuit= 40 V. RG (in the gate circuit)=100 ohm. RL in the output circuit =2k. A small ac voltage is in the input circuit.
i) Draw the dc and ac equivalent circuits
ii) Draw the I-V curve on the output. Show the value of the saturation knee- point. Show the load line and intersection(Q) point. Calculate the Q point values for current(IDS) and voltage(VDS)
iii) Calculate trans-conductance gm.
iv) Calculate the amplification factor.

6. Now I use the MOSFET of #5 as a logic gate – inverter. Assume that the I-V curve only has two regions-linear from 0V to knee point for saturation, and then saturation I value(two straightlines). Using this approximation, draw IDS vs. VDS curves (to scale) for values of VGS increasing by 1 V from 0V. A family of curves will result- 5 in all. Label each one with the VGS value. What is the value of the output voltage when the MOSFET is used as an inverter with VGS= 4V? What is the current?

2:Science and the Environment

Water Science and the Environment

Stream stage and flow, rating curve; soil porosity and water content
Problem 1. Creating own rating curve from field measurements of flow and water level.
Flow velocities were measured using the floater method during different water levels. The following
measurements were obtained: travel time (t), of the floater over distance L (from which the
water velocity can be computedusing this formula: v = L/t*0.85; the constant 0.85 converts surface
velocity that was measured to average velocity in water profile), water depth (d), and water
width (w) (from depth and width the cross-sectional area can be computed: A = d*w), and water
level (h)(stream stage). All measurements were made on a number of segments at the same point
in the stream (see diagram for details). In this exercise we use these measurements to compute the
total flow rate of the stream, and then relate this total flow rate to the water stage. Several flow
rate – water stage points can be used to define the rating curve.
The data are here:
Date segment depth, d width, w distance, L time, t
i ft ft ft s
Point #1 1 0.79 1.6 15 56
06-Aug-16 2 0.82 1.6 15 64
Stage: 1.09 ft 3 0.85 1.6 15 30
4 1.02 1.6 15 33
5 1.05 1.6 15 19
6 1.05 1.6 15 20
7 1.15 1.6 15 20
8 1.02 1.6 15 24
9 1.08 1.6 15 23
10 1.08 1.6 15 25
Point #2 1 0.33 1.64 15 25
07-Aug-16 2 0.49 1.64 15 12
Stage: 1.21 ft 3 1.02 1.64 15 18
4 1.02 1.64 15 24
5 0.98 1.64 15 19
6 1.08 1.64 15 19
7 1.31 1.64 15 10
8 1.31 1.64 15 12
9 1.35 1.64 15 12
10 1.18 1.64 15 14
11 0.89 1.64 15 10
12 0.85 1.64 15 14
13 0.66 1.64 15 26
14 0.46 1.64 15 28
Point #3 1 1.15 1.64 15 11.3
11-Aug-16 2 2.10 1.64 15 6.3
Stage: 1.50 ft 3 2.03 1.64 15 8.1
4 2.20 1.64 15 7.1
5 2.23 1.64 15 5.4
6 2.07 1.64 15 7.5
7 1.84 1.64 15 7.4
8 1.21 1.64 15 8.3
9 1.05 1.64 15 11.2
Point #4 1 0.92 3.28 15 31
12-Aug-16 2 1.20 3.28 15 13
Stage: 1.19 ft 3 1.29 3.28 15 10
Required:
(a) Compute flow rate in each segment in the table. Each line should have its own flow rate. Then
add up segments withing each point; this will be total flow rate at that time. Make a table
showing flow rates and river stage; you should have six entries, one for each point.
(b) Plot the data and fit a line (put stage on the horizontal axis and flow rate on the vertical axis).
This is your rating curve for the Sabino Creek. You will be asked to compare this with USGS
rating curve in Problem 2.
Problem 2. Reconstructing (reverse engineering) rating curve from USGS data on water
level and flow rate.
Use USGS stream gauge data to reconstruct the rating curve for the Sabino Creek.
The data are here: http://waterdata.usgs.gov/az/nwis/uv?site_no=09484000
Required:
(a) Download data for time period between 10 January 2017 and 30 January 2017 (this period
includes the highest flow rate in the past several years). Plot water level (on x axis) vs. flow
rate (on y axis).
(b) Fit a line through the data; this is the rating curve. What function best approximates the data?
(c) Compare with your rating curve from Problem 1. How similar or different are the two?
Explain briefly.
4 1.22 3.28 15 12
5 1.21 3.28 15 13
Point #5 1 0.95 2.95 15 33
15-Aug-16 2 0.98 2.95 15 35
Stage: 1.06 ft 3 0.92 2.95 15 32
4 0.56 2.95 15 62
Point #6 1 1.61 3.28 15 18
08-Sep-16 2 1.67 3.28 15 10
Stage: 1.36 ft 3 1.87 3.28 15 9
4 1.80 3.28 15 9
5 1.67 3.28 15 12
Extra credit: 25%
Problem 3. Soil properties and water content.
A soil sample was collected using a tube 5 cm long and 5 cm in diameter. The wet soil sample
weighs 165.9 g. After oven drying the mass of the sample was 151.2 g. The soil grains are made
of mineral quartz with grain density of 2.65 g/cm3
.
(a) Compute the volumetric soil water content (volume of water divided by volume of sample),
the wet bulk density of the soil (mass of wet soil divided by volume), and the dry bulk density.
(b) Compute the porosity of the sample (volume of pores divided by total v

3: Academy Awards Attestation Planning

Design an attestation plan for the annual voting procedures of the Academy of Motion Pictures in selecting the Academy Award winners. The Academy currently engages PricewaterhouseCoopers (hereafter PwC) to provide this attestation. To begin your research, I suggest that you familiarize yourselves with the actual voting procedures utilized by the Academy and PwC.
Then, research the procedures performed by PwC. I searched the firm’s website, www.pwc.com, for Academy Awards and found several relevant documents.
Based on the Academy’s voting procedures, identify the process-level risks and the related controls. Then, relate each of PwC’s main procedures to these process-level risks and/or control and describe them as either control tests, analytical procedures, or substantive tests.
Finally, try to identify weaknesses in the Academy’s and/or PwC’s procedures, and recommend improvements.
Your presentation should address the following issues:
1. Describe the Academy’s voting procedures
a. After nominees are announced Ballots are sent to each member of the academy (Can either vote electronically or with a paper ballot the choice is up to each individual academy member.)
b. A small group of PWC employees count each vote by hand at a secret location
c. When voting with a paper ballot the academy member puts the ballot in an envelope that’s indicated with security codes
d. PWC makes sure each ballot they receive is legitimate by matching the code on it to its corresponding voting member
e. The voting takes place in multiple rooms with security and biometric locks as well as alarms set up to call LAPD if doors are left open for too long
f. Once the ballots are counted they are filed away for a few years and then shredded
g. The best picture is calculated slightly different than the others. It uses preferential voting with the members ranking the nominees. After figuring out which nominee received the least amount of votes that one is taken out. They then look at which movie the voters who favorite was eliminated put second and the process starts over again. This goes on until there are two movies left. The one with the most votes in that round eventually wins
h. Winner cards and envelopes are created for each nominee, these are then given to another person who puts the correct winner card in the envelope and shreds the other ones. The winners are then put in a briefcase.
i. Two members of PWC travel to the awards with winner cards in two separate briefcases. To ensure security the two take a different route to the awards
j. The two never leave the briefcases and stand back stage with an LAPD escort and they hand the winner envelopes to the presenters right before they walk on stage.
What are the process-level risks inherent in the procedures?
. The risk of false ballot
a. The risk the ballots and winner cards are tampered with or replaced
b. The risk the ballots or winner cards are stolen
Does the Academy have controls in place to address these risks? (The PWC attestation is a control, but assume this control is not in operation. If you cannot identify any controls, you will obviously need to increase your substantive testing.)
a. Ballot security codes corresponding to the academy members is a control over the risk of false ballot
b. The security measures taken in the place of counting are controls over the risk of ballots and winner cards being tampered with or replaced
c. Shredding the unused winner cards is a control over the risk of ballots and winner cards being tampered with or replaced
d. The two separate brief cases and taking them on separate routes is a control over the risk of the ballots and winner cards being tampered with replaced or stolen
e. The LAPD security and only giving the card right before the presenter goes on stage is a control over the tampered with or replaced ballots as well as the cards being stolen
Does PwC rely on these controls? What control tests do they perform? Do you recommend additional control tests?
Answer:
How do PwC’s attest procedures assess the uncontrolled risks? Identify the specific substantive tests that they perform. Do you recommend additional substantive tests?
Answer:

Academy Awards