For a base motion system described by:
mx''+ cx'+ kx = cY?b cos ?bt + kY sin ?bt
with m = 100 kg, c = 50 N/m, Y = 0.03 m, and ?b = 3 rad/s, find largest value of the
stiffness k and that makes the transmissibility ratio less than 0.75.
In: Mechanical Engineering
Naphthalene is commonly used as a repellent against
moths to protect clothing during storage. Consider a 1 cm diameter
spherical naphthalene ball hanging in a closet at 25 oC. The
density and vapour pressure of naphthalene at 25 oC are 1100 kg/m3
and 11 Pa, respectively and mass diffusivity of naphthalene in air
at 25 oC is 0.61 x 10-5 m2/s.
a. consider the variation of diameter with time,
determine how long it will take for the naphthalene to sublimate
completely.
b. If instead of being stored in a closet, the
naphthalene is exposed to dry air flowing at a velocity of 2 m/s.
Both the naphthalene and the air were kept at 25 oC. It is observed
that 12 g of naphthalene has sublimated in 15 min. Determine the
mass transfer coefficient and the flux for mass transfer from
naphthalene.
In: Mechanical Engineering
Explain with your own words, how turbulence increases heat transfer.
In: Mechanical Engineering
If a candle is lit in a spacecraft without gravity...
Question 8 options, pick one:
|
a. The candle will light, but not burn very well, as no natural convection flows develop. |
|
|
b. The candle will not light. |
|
|
c. The candle will light and burn better than on Earth, as the natural convection flows are not held down by gravity. |
|
|
d. The candle will light and burn just like on Earth, as natural convection flows are independent of the gravity. |
In: Mechanical Engineering
Materials Science
What are the frequently observed problems of using polymer materials in cars ?
In: Mechanical Engineering
What are designs/devices being used today for finger joint replacements (MCP) *include about 3 or more devices*
1. Description of each device (mechanics involved)
2.FDA class
3. Which current design is the most used today
Please include citations from the information obtained
Thank you
In: Mechanical Engineering
In: Mechanical Engineering
Discuss the steps in producing a clay-based ceramic from slip clay. Be specific and describe all steps and there effect on the micro-structure of the material - in particular why is the original material called slip clay.
In: Mechanical Engineering
In: Mechanical Engineering
An industrial gas turbine operates at an 8.8:1 pressure ratio
and a mass flow of 77 kg/s. The
exhaust temperature is at 437?C and the inlet temperature to the
machine is around 1000?C.
The machine is to be designed for a constant axial velocity of 200
m/s. (This data is based on
the Rolls-Royce Avon, an engine that dates from the 1950s but is
still used as low efficiency
high reliability engine for stationary power such as pipeline
pumping.)
For this gas turbine, draw to scale the meridional view with:
(a) a constant mean radius of 0.4 m.
(b) a constant outer diameter (to minimise cross sectional area) of
1.05 m.
In: Mechanical Engineering
Calculate the MRR in a drilling process that is done with a 2 1 4 - inches radius drill bit, in one piece whose drilling depth is H = 5 3 8 inches and it takes 1/2 hr. Keep in mind that the perforation is not through the workpiece and that the conical tip of the hole has a height of ½ inch.
In: Mechanical Engineering
An industrial gas turbine operates at an 8.8:1 pressure ratio
and a mass flow of 77 kg/s. The
exhaust temperature is at 437?C and the inlet temperature to the
machine is around 1000?C.
The machine is to be designed for a constant axial velocity of 200
m/s. (This data is based on
the Rolls-Royce Avon, an engine that dates from the 1950s but is
still used as low efficiency
high reliability engine for stationary power such as pipeline
pumping.)
For this gas turbine, draw to scale the meridional view with:
(a) a constant mean radius of 0.4 m.
(b) a constant outer diameter (to minimise cross sectional area) of
1.05 m.
In: Mechanical Engineering
Viscoelasticity and the non-linear rheology of polymers are responsible for phenomena such as rod climbing or die swell as well as part of the challenge of processing polymer melts. 1) explain why from a polymer physics point of view polymer melts can have non-Newtonian behaviors that do not scale linearly with molecular weight and 2) explain what one of these two examples are and posit an explanation for it.
In: Mechanical Engineering
1) A four-stroke diesel engine has a piston diameter of 16.5 cm and a stroke of 27 cm. The compression ratio is 14.3, the cut-off 4.23% of the stroke and the mean effective pressure 4.12 bar. The engine speed is 264 rev/min and the fuel consumption is 1.076 kg of oil per hour, having a calorific value of 39150 kJ/kg. Calculate the relative efficiency of the engine 2). A diesel engine has a brake thermal efficiency of 30%. If the calorific value of fuel used in 10000 kcal kg, calculate the brake specific fuel consumption
In: Mechanical Engineering
I am planning on purchasing a new Tractor, There are two machine choices, Tractor A and Tractor B. Tractor A will cost $175,000 and Tractor B will cost $275,000. Due to various uncertainties in manufacturing operations, the useful life of each machine is unknown, but the following probability estimates have been made.
|
Useful life (years) |
Probability |
|
|
Machine A |
Machine B |
|
|
15 |
0.15 |
0.25 |
|
25 |
0.25 |
0.45 |
|
35 |
0.45 |
0.20 |
|
45 |
0.15 |
0.10 |
A. Determine the expected life of each machine.
B. Based on the ratio of purchase cost to expected life, which machine would you recommend?
In: Mechanical Engineering