In: Mechanical Engineering
Q] What are the advantages and disadvantages of acceptance sampling over 100% inspection? Under what conditions should acceptance sampling be preferred over 100% inspection?
Subject - Materials Management
In: Mechanical Engineering
3. One mole of air is compressed isothermally at 300K from one
atmosphere to fifteen atmospheres.
a) Calculate the amount of work required in the compression.
b) How much heat must be added or removed from the gas to maintain
its temperature at 300K.
c) Does the enthalpy of the gas change? If so, how much?
d) Does the entropy of the gas change? If so, how
much?
DATA: You may assume that air is an ideal gas with a constant
volume heat capacity of 5/2R
In: Mechanical Engineering
Liquid penetrant testing is a suitable method for almost any material. What can not be inspected by liquid penetrant testing method?
Explain why pre-cleaning is the most important step
Imagine a part that contains fatigue cracks which are detectable under no load using liquid penetrant technique. Would they still be detectable under tensile and compressive loads and why?
List the main human factors that affect the probability of detection in liquid penetrant testing.
What control measures should be considered in developer thickness layer?
List the advantages and disadvantages of the various developer types.
Additionally there are 10 marks given for organisation and presentation. You will be expected to show evidence of research and well balanced arguments supported by academic literature relevant to the problem (in addition to the learning package material). Note that that the marking scheme gives an indication of the expected length of each section. Explanations and descriptions should reflect this balance between sections and sub-sections.
In: Mechanical Engineering
A nozzle is is designed to achieve M=4 under expanded exit flow conditions. For the given total pressure and total temperature, calcuate:
a) exit Mach
b)mach at which normal shock occurs in the model
In: Mechanical Engineering
13.3 Why are clear objectives and standards needed in the appraisal process?
In: Mechanical Engineering
13.2 Why do supervisors appraise their employees? What in the process will benefit supervisors? What will benefit their employees?
In: Mechanical Engineering
In a surface condenser a section of the tubes near to
the air pump suction is
screened off so that the air is cooled to a temperature below that
of the condensate, separate extraction
pumps being provided to deal with air and condensate respectively.
5448 kg of steam are condensed
per hour and the air leakage is 4.54 kg/h. The temperature of the
exhaust steam is 31°C, the temperature
of the condensate is 27°C, and the temperature at the air pump
suction is 21.1°C. Assuming a constant
vacuum throughout the condenser, find
() The mass of steam condensed per hour in the air cooler;
(i) The volume of air in m3/h to be dealt with by the air
pump;
(ii) The percentage reduction in necessary air pump capacity
following the cooling of the air..
In: Mechanical Engineering
15.3 What does the Wagner Act prohibit?
In: Mechanical Engineering
Why are the parts manufactured using powder metallurgy of near net shape? For mixtures of dissimilar metal powders, explain how (a) blending/mixing, and (b) compaction are carried out before sintering. Explain how (i) blending/mixing and (ii) compaction steps influence the (a) sintering step and (b) porosity development in the processed part.
In: Mechanical Engineering
Define the phenomenon of Springback in sheetmetal forming, and provide a detailed explanation of the methods used to compensate for springback in finished sheetmetal products.
In: Mechanical Engineering
In: Mechanical Engineering
For each of the following pairs of polymers, plot and label schematic stress-strain curves on the same
graph [i.e. make separate plots for parts (a), (b) and (c)].
(a) Polychloroprene rubber having a number-average molecular weight of 100,000 g/mol and 15% of available sites cross-linked; liner polypropylene having a number-average molecular weight of 150,000 g/mol.
In: Mechanical Engineering
Consider a converging-diverging nozzle with an exit-to-throat area of 3. The inlet reservoir pressure is 1 atm and the exit pressure is 0.5 atm.
(a) For this pressure ratio a normal shock will stand somewhere inside the divergent portion of nozzle. Calculate the location of shock (A/At =?).
(b) back pressure if the flow were isentropic throughout.
In: Mechanical Engineering
In a combined cycle of gas turbine, can a steam turbine drive the same generator driven by the gas turbine? Or it must drives a separate generator?
Also, is there any gas power station that uses a gas other than natural gas? Please give an example. Also, is there a gas power station that uses synthesis gas?
In: Mechanical Engineering