How does inserting parts to form subassemblies save time in documenting designs?

In class, we learned that ”most” of the sun’s radiation happens in the band 0.2 ? ? ? 3µm, and Stephen asked what ”most” means. What proportion of solar radiation (for a black body sun) falls in the above wavelength range. Similarly, what proportion of the Earth’s radiation (black body Earth at 290K) occurs in the wavelength band 4 ? ? ? 40µm? What wavelength range contains the middle 95% of the sun’s radiation?

For the solidification of pure gold, calculate the critical radius (r*) and the activation freeenergy (\Delta G?G*). Assume homogeneous nucleation conditions. The values of the latent heat of fusion and the surface free energy are -1.16x109 J/m3 and 0.132 J/m2, respectively. The degree of supercooling is 230 K and the melting point of gold is 1064 oC.

what is the enthalpy value of steam at 1.9 MP and 290 C?

Oxygen is contained in a piston-cylinder system initially at a temperature of 40 ^oC and a pressure of 150 kPa. The piston is 1 m in diameter and initially 20 cm above the base of the cylinder. Heat is added at constant pressure until the piston has moved 30 cm, so it's now at 50 cm.

I found the mass of the system to be 0.2898 kg, and T2 = 783K.

a) Using the table of properties of oxygen as an ideal gas, calculate the heat added to the system per unit mass, in kJ/kg

b) Repeat this calculation assuming that the specific heat as a function of temperature is linear over this range of temperatures (ie, assuming the change in temperature is "small")

c) Repeat this calculation without this assumption (ie, direct integration of empirical relation)

Refrigerant 134a enters an insulated compressor operating at steady state as saturated vapor at -20^oC with a volumetric flow rate of 0.18 m³/s. Refrigerant exits at 9 bar, 70^oC. Changes in kinetic and potential energy from inlet to exit can be ignored.

Determine the volumetric flow rate at the exit, in m³/s, and the compressor power, in kW.

The following design and operating data were taken for a large industrial centrifugal water pump:

Required water flow rate varies from 500 m3/h to 700 m3/h. For the pump to deliver 550 m3/h, the flowrate has been reduced by partially closing the delivery valve. Motor efficiency is 93%.

a. Calculate the pump operating efficiency (the ratio of pumping power to operating pump input power delivered TO THE MOTOR.

b. Pump operating efficiency is low because of the partial valve closing to control the flowrate. What would be the best way to improve pump operating efficiency?

c. The ratio of two pump volumetric flowrates would be equal to the ratio of two pump shaft speeds to what power? The ratio of two pump operating heads would be equal to the ratio of two pump shaft speeds to what power? The ratio of two pump operating powers would be equal to the ratio of two pump shaft speeds to what power?

d. Suppose the pump energy improvement idea suggested in part b. was used for the pump. From the relations in part c., calculate the pump speed required to give a volumetric flowrate 550 m3/h. That is, (550 m3/h / design flowrate) = (RPM to deliver 550 m3/h / design RPM). From this, calculate the pumping power needed to deliver 550 m3/h using the design pumping power ratio. The difference in the operating values of the pumping power (124 kW and the pumping power with the new energy efficiency feature) is the energy savings.

Machine X costs $248,751 and has annual operating and maintenance costs of $9,980. Machine Y costs $264,500 and has annual operating and maintenance cost of $5,120. Both machines are Class 39, which specifies a CCA rate of 25%. The company needs the machines for 11 years, and at the end of year 11 machine X can be sold for $12,257 and machine Y can be sold for 13,033. The Company's MARR is 10%, and its marginal tax rate is 35%. Do an after-tax analysis to determine which machine should be chosen.

There is a vapor compression type refrigeration cycle using the refrigerant HFC 134 a. In the condenser, it is isostatically cooled, the condensation temperature is 50 ° C., and the condenser outlet is the compressed liquid at 45 ° C. In the evaporator, it is isothermally heated, the evaporation temperature is 10 ° C. and the outlet of the evaporator is heated steam at 15 ° C. When the expansion valve performs isenthalpic expansion, and the adiabatic efficiency of the compressor is 0.70, answer the following questions.

(a) Calculate the specific enthalpy of the compressor outlet temperature, specific enthalpy, condenser outlet and evaporator outlet.
(b) Obtain the cooling operation coefficient of this system.
(c) Obtain the circulation amount of the refrigerant necessary for obtaining the cooling effect of 3.0 kW in this system.

Answer:
(a) Compressor outlet: 68 ° C, 445 [kJ / kg], condenser outlet: 264 [kJ / kg]
Evaporator outlet: 409 [kJ / kg] (b) 4.03 (c) 0.021 [kg / s]

Consider a double wedge airfoil with a maximum thickness of 5% chord at angle of attack = 0 degrees.

a. Determine the approximate chord wise location (x/c) of the maximum thickness that producesthe minimum drag coefficient (cd) at Mach numbers of 2, 4 and 6. [Hint: you do not need to investigate locations ahead of 0.4c]. Include a composite plot of drag coefficient vs location of (t/c) max for each Mach number in your report.

b. Repeat this analysis for an airfoil with 10% maximum thickness. Include the calculated values on your composite plot of part I.a.

c. Discuss what your results say about the effects of Mach number and thickness on minimum drag coefficient.

Write a brief note about the type of fits and tolerances in machine elements subject under mechanical engineering

Part 1. Select an object from your everyday life that GD&T could be applied to. Attach a graphic image of it (a photograph, a scanned sketch or a computer generated drawing) in JPEG format here.

Part 2. Identify two primary functions of this part (e.g. must assemble to other part(s), smooth rolling, must not wobble when placed on a flat surface). Briefly describe the functions (maximum of 200 words).

Part 3. Assign a minimum of two geometric tolerances (including at least one that requires the use of datums) to the part to ensure that the part will successfully achieve its two primary functions. Assign datums as necessary. Create a sketch or drawing to show where the datums and tolerances will be applied. Assign values for the tolerances, however you will not be marked on the magnitude of the tolerances.

Part 4. Briefly describe (maximum of 150 words) how the part would be inspected to verify that it meets the geometric tolerances.

Q4. Explain the concept of kinematic coefficients? Why do we need to “square” and “cube” the angular velocities, in order to obtain time derivatives using the second order and third order kinematic coefficients, respectively?

The velocity profile for a steady laminar flow in a circular pipe of radius R given be u=u0( 1- r^2/R^2). if the fluid density varies with radial distance r from the centerline as p=p0 ( 1+ r/R)^1/4 where p0 is the fluid density at the pipe center, obtain a relation for the bulk fluid density in the tube.

A request has been received from an external customer for recommendations for linear position control sensors to be used in an explosive environment. For this reason unsafe electrical contacts must be avoided. The sensors will be installed in locations that are hazardous to access except when the plant is shut down annually for maintenance. The span required is 5 cm. The sensor case must not permit any ingress of dust or of water.

State what type of position sensors you would recommend and give your reasons. Sketch both the recommended sensor and circuit, and explain its operation. Comment on how signal conditioning requirements can now be met. Identify the durability required in respect of dust and water ingress.