In this exercise we will utilize the tables for superheated water vapor, (D-3). All graphs should be generated using plotting software, e.g. Excel, MatLab, etc. (If you use NIST, do NOT utilize the built-in plotting software to generate your graphs.) Plot the specific internal energy and the specific enthalpy Vs T(K) at 1 bar. (Use a reasonable number of available temperature values but include the maximum and minimum values.) The lower limit of the ordinate should be 2500kJ/kg and the lower limit of the abscissa should be 300K. Observe the nature of the relationships and based on these calculate the ratio of specific heats, gamma. Plot the compressibility factor as a function of temperature for 1 bar and 120 bar and comment on the significance of intermolecular forces. The compressibility factor of a gas is 0.94152 when the temperature, pressure and specific volume are -50 degree F, 30atm and 0.018317m^3/kg, respectively. Which gas is it?

(a) If you want to extrude a Y-shaped profile, what is the maximum allowable branch length you can obtain if you use a 4” billet? The Y-shaped profile has a design that contains three equal length of branches, 30° angle between the top two branches, and a wall thickness of 4 mm throughout.

(b) If the Y-shaped profile is extruded from “easy” aluminum alloys with an exiting speed of 60 m/min, how long does it take to finish one extrusion process using a 6 feet long billet? (Hint: Make assumptions on when extrusion starts and stops.)

Consider 6.9 kg of austenite containing 0.40 wt% C, cooled to below 727˚C (1341˚F).

(a) What is the proeutectoid phase?
(b) How many kilograms each of total ferrite and cementite form?
(c) How many kilograms each of pearlite and the proeutectoid phase form?

See Animated Figure 9.24

At the beginning of the compression process of an air standard Otto cycle, p1 = 1 bar, T1 = 300 K. The maximum temperature in the cycle is 2250 K and the compression ratio is 9.8. The engine has 4 cylinders and an engine displacement of Vd = 2.6 L. Determine per cylinder:

a) the volume at state 1. (IN LITERS) I have tried 2.8L 0.945 L and 0.789 L but i keep getting it wrong.

b) the air mass per cycle.

c) the heat addition per cycle, in kJ.

d) the heat rejection per cycle, in kJ.

e) the net work per cycle, in kJ.

f) the thermal efficiency.

g) the mean effective pressure, in bar.

h) Develop a full exergy accounting per cycle, in kJ. Let T0 = 300 K, p0 = 1 bar. i) Devise and evaluate the exergetic efficiency for the cycle.

A 4-cy wheel loader will be used to load trucks from a quarry stockpile of uniform aggregates (1" and over in size). The haul distance will be negligible. The aggregate has a loose unite weight of 2,750 lb/cy. Estimate the loader production in tons based on a 50 min-hour efficiency factor. Use a conservative cycle time and fill factor.

A string of length L = 1 is held fixed at both ends. The string is initially deformed into a shape given by u(x, t = 0) = sin^2(πx) and released. Assume a value of c2 = 1. Find the solution u(x, t) for the vibration of the string by separation of variables.

If the bond stiffness and bond length of the carbon to carbon bond are 90 N/M and 154 pm respectively estimate the youngs modulus of diamond. B) The structure of thermoplastics also contain many carbon to carbon bonds, but the elastic moduli of thermo =plastics are commmonly two orders of magnitude lower than that of diamond. Why?

Practice for Matlab. You can create own f(x).

a. Write code to find and plot a root using the modified secant method

b. Find the roots using the roots command - identify and plot root of interest

c. Use polyder and roots to find and plot the minimum value

d. use fminbnd to find and plot minimum value

Thank you!

The total cycle time of an automatied fiber placement (AFP) operation (sheet lamination), used to manufacture a section of the airplane fuselage, is 8 hours and 40 minutes. The setup time before the start of the operation is 10 minutes. After each layer is put down, an inspection stage is performed for 5 minutes. The AFP head requires cleaning cycle of 3 minutes every 7 layers.

a. If the part is made of 20 layers, what is the time required (in minutes) to lay down 1 layer?

b. What is the percentage of down time for this operation?

c. What is the total cycle time (in minutes) for making this part, if the lay down speed was doubled?

A reputable engine company has been making carbureted spark-ignition engines that operate with an equivalence ratio = 1.0 and a compression ratio of 9:1 for years. In order to control emissions, the engines operate with 20% exhaust gas recirculation (EGR) and a three-way catalytic converter. Since the company’s market share is steadily dropping, they consider hiring a MEC graduate to rescue them. The ambitious young engineer proposes a port fuel-injected (PFI) design, which operates lean at 0.7 with a high compression ratio (15:1) and vigorous inlet swirl. The new engine has the spark-plug mounted at the center of the combustion chamber, while the production engine has the spark-plug at the side.

(a) Will the flame development period of the new chamber be shorter, longer, or about the same as the current design?

(b) Will the rate of the combustion of the new chamber be faster, slower, or about the same as the current design?

(c) Sketch the mass fraction burned vs. crank-angle curves for these two combustion chambers when spark-timing is set for maximum brake torque. Clearly label the sparktiming, ignition delay, and overall burn duration for each case.

(d) The engineer claims that the proposed lean-burn engine will have the same octane requirement as the production SI engine. Could this claim be true?

(e) Will the proposed lean-burn engine clearly develop greater power at full load than the current SI engine?

(f) Would there be any additional advantages or disadvantages if the proposed engine were direct-injected, stratified charge, instead of homogeneous, operating at the same overall equivalence ratio?

Discuss the interactions of mechanical engineering with other disciplines at arkansas nuclear

Question 1. Samples of n = 4 items are taken from a process at regular intervals. A normally distributed quality characteristic is measured and x-bar and s values are calculated at each sample. After 50 subgroups have been analyzed, we have

? x?_i = 1,000 and ? s_i = 72

(A) Compute the control limit for the x and s control charts

(B)Assume that all points on both charts plot within the control limits. What are the natural tolerance limits of the process?

(C) if the specifications limits are 19 + 4.0 what are your conclusions regarding the ability of the process to produce items conforming to specifications?

(D) Assuming that if an item exceeds the upper specification limit it can be reworked, and if it is below the lower specification limit it must be scrapped, what percentage scrap and rework is the process now producing?

(E) If the process were centered at u = 19.0, what would be the effect on percentage scrap and rework?

Dislocation in metals

Describe edge dislocation motion in metals from an atomic perspective. Be sure to clearly illustrate the sequence in which bonds are broken and reformed.

Also from an atomic perspective, describe how macroscopic plastic deformation occurs by the motion of dislocations in response to an applied stress. Again, use words and visuals to explain.

how does a compressor can make a recording appear to sound louder.

The convection coefficient for flow over a solid sphere may be determined by submerging the sphere, which is initially at 25 °C, into the flow, which is at 75 °C, and measuring its surface temperature at some time during the transient heating process. If the sphere has a diameter of 0.1 m, a thermal conductivity of 20 W/(m·K), and a thermal diffusivity of 4.0×10-5 m²/s, at what time will a surface temperature of 60 ºC be recorded if the convection coefficient is 300 W/(m²·K)?

a) When deciding if the lumped capacitance method can be used, what is the value of the Biot number?

Bi c= 0.2505 ( correct)

b) When using the one-term approximation for transient 1-D conduction, what is the value of the applicable Biot number? Use Table 5.1.

Bi=??

c) Using the one-term approximation, if Bi in Table 5.1 were equal to 0.5, what would be the value of C1 for this problem?

C1=??

d) Use the one-term approximation method to solve for the Fourier number.
F0=??

e) Solve for the time required for the surface of the sphere to reach 60 ºC, in sec.

t=?? sec