One integrated circuit design calls for the diffusion of arsenic into silicon wafers; the background concentration of As in Si is 2.5 × 1020 atoms/m3. The predeposition heat treatment is to be conducted at 1000°C for 45 minutes, with a constant surface concentration of 8 × 1026 As atoms/m3. At a drive-in temperature of 1100°C, determine the diffusion time required for a junction depth of 1.2 μm. For this system, values of Qd and D0 are 4.10 eV and 2.29 × 10−3 m2/s, respectively. (The answer is NOT 49.12hours)

Leaf springs are commonly used in low-cost or high-stiffness vehicle suspensions, e.g. golf cars, light-truck rear axle. Consider a cold-drawn AISI 1040 flat leaf spring subjected to a fluctuating loading condition of maximum and minimum stresses of 420 MPa and 140 MPa respectively for a total of 50,000 cycles. The loading condition of the spring then changes to maximum and minimum stresses of 350 MPa and -200 MPa respectively. Estimate the remaining life of the spring under the new loading condition using Palmgren-Miner cumulative damage theory. Assume that the fully-corrected endurance limit is 200 MPa and Sn is 90% of Sut.

As mechanical engineering explain the reason why an early airbag was a failure, and the reason any system acquisition processes that were not followed that may have contributed to the failure.

(H) Angle conversions. 2.47 deg = A rad.  3.72 rad=B deg. 3.67 rad=C rev.
     3.0300 rad = D deg E min F sec.  Round F to the nearest second. There are 6 answers.

1. Using the equations describing the standard atmosphere, plot the speed of sound (in m/s, ft/s and knots) in the altitude range sea level – 32 km. You can use Matlab or Excel (10 points).


2. An airfoil has a critical Mach number of ??? = 0.65. The wing is swept back at 30°. a) What is the design flight Mach number for this wing? (2 points)

b) What is the design flight speed in knots at an altitude of 30,000 ft? (10 points)


3. A supersonic passenger plane is traveling at an altitude of 60,000 ft. A normal shock forms in front of the nose of the plane. A pitot-static system on the nose (behind the shock) measures the pressure ratio between stagnation pressure and static pressure to be 1.2256. a) Calculate the flight Mach number of the aircraft (12 points).

c) Calculate the required wing sweep for minimum wave drag. (4 points)


3. A fighter jet passes over you at Mach 1.6 at an altitude of h = 10000 m. What is its horizontal distance x from you when you hear the sonic boom? (6 points)

Design an electro-pneumatic circuit to control a double-acting cylinder via a 5/2 way singlesolenoid valve. The on switch is of detent type and when actuated, the piston will repeatedly extend and retract until the switch is released. The length of forward stroke and the speed of forward and return motion should be adjustable via roller-limit switches and flow control valves respectively.

(a) Show pneumatic and electrical circuits for indirect control of the system described above, i.e. each switch in the circuit indirectly controls the output components via a dedicated relay. [15]

(c) Redesign your circuit incorporating non-contact sensing for piston position detection using three-wire capacitive sensors.

Part 2: MATLAB

Exercise 1 (50 pts)

Write a program that tells the user if a city of their choice is in a tropical, temperate, or polar region. Use the cities.txt file provided in the Files section of this class. Your program should read the data in that file, find the city given by the user, and return a text message with the information. If the city is not found, your program should write a message accordingly. To decide which region each city falls into, use the table below.

HINT: If you follow the file reading methods explained in our video tutorial, your data will be in cell format. There are a few functions that could be very useful in this case: strcmp compares two strings (one of which can be in a cell) to see if they match. Also, cell2mat converts a cell array into an ordinary array. Finally, find finds indices and values of any non-zero elements in an array.

See the output examples below:

What city are you interested in? Caracas
Caracas is in a tropical region 

What city are you interested in? Merced
City not found! 

https://catcourses.ucmerced.edu/files/1587454/download?download_frd=1

1.What is the purpose of the diffuser section of a gas turbine engine, and under what principle does it operate?

2.Why do some axial flow gas turbine engines use multiple compressors?

3.What happens in a compressor stall?

4.Why is a variable exhaust nozzle required in an engine equipped with an afterburner?

Q) Explain in brief, the importance of Energy Auditing and Energy Management. With the use of a case study, explain its significance at your workplace?

Air undergoes a polytropic process in a piston–cylinder assembly from p1 = 1 bar, T1 = 295 K to p2 = 7 bar. The air is modeled as an ideal gas and kinetic and potential energy effects are negligible. For a polytropic exponent of 1.4, determine the work and heat transfer, each in kJ per kg of air, (1) assuming constant cv evaluated at 300 K. (2) assuming variable specific heats.

A Copper plate that is 588mm wide and 48 mm thick is to be reduced in a single pass in a two high rolling mill by using a 321mm diameter roll. The coefficient of friction at roll workpiece interface is  0.14 and the roll rotates at 107rpm. The rolling process is performed above the recrystallization temperature of the material and the width of the plate does not change during this operation. What is the minimum final thickness (mm) possible

2. Define a process for finding a job. For what types of endeavor does a well-defined
process enhance performance?

Diagram a process for planning and cooking a family dinner. Does your process re-
semble the generic product development process? Is cooking dinner analogous to amarket-pull, technology-push, platform, process-intensive, customization, high-risk quick-build, or complex system process?

Describe the difference between a substitutional solute atom, an interstitial solute atom, and a vacancy. Discuss whether the stress in the material near the defect will be tensile or compressive

Re-derive the coefficient of pitching moment equation for the aircraft in the previous problem.Note: Use the corresponding free body diagram and build-up method for the derivation.