State the Bragg’s law and how it is used for X-ray analysis.

State the advantages of the field-emission electron gun over the tungsten electron gun.

State the functions of electromagnetic lenses in an SEM/EPMA.

If you have a piece of rock sample in dimensions of 10 ´ 10 ´ 10 mm³, briefly state how to prepare it for the EPMA studies.

When your rock sample is prepared, state what information you can get using the EPMA instrument.

Subject: Heat exchanger Lab

Question:

1.1) in heat exchanger analysis, the following quantities are used. Explain what each means and give
a formula for each. Assume the mass flow rates, fluid properties, inlet, temperatures, and length
and diameters of the heat exchanger are known.

a) Overall heat transfer coefficient. UA.

b) A number of transfer units, NTU.

c) Effectiveness, e

1.2) what is the hydraulic diameter and why is it useful for double-pipe heat exchanger analysis?

1. (a) Outline the principles and essential differences between Continuous Cooling Transformation and Isothermal Transformation Diagrams

   (b) Using the TTT diagram for a plain carbon steel with 0.53%wt C, define the nature of the final microstructure (in terms of micro-constituents present and approximate percentages) of small samples (5 x 5 x 5 mm) subjected to the following time-temperature heat treatments.In each case, assume that the specimen was austenitised at 860?C and held at this temperature long enough to achieve a homogeneous austenitic structure prior to cooling.

(i) Rapidly cool to 500^oC, hold for 7s, rapidly cool to 400oC, hold for 103s and water quench to room temperature.

(ii) Rapidly cool to 400^oC, hold for 7s and water quench to room temperature.

(iii) Rapid cooling to room temperature within 1s.

(iv) Rapidly cool to 650^oC, hold for 1h and water quench to room temperature.

(v) Rapidly cool to 400^oC, hold for 1s, followed by water quenching to room temperature.

1. Water at a flow rate of = 0.25 kg/s is cooled from 70 C to 30 c by passing it through a thick-walled tube of internal diameter of Di =50 mm and an external diameter of D = 60 mm. Hot Water is cooled by blowing cold air at T? = 15 C in cross flow over the tube. Velocity of the air over the tube is 20 m/s. Evaluating the water properties at 325 K from Table A.6 and evaluating air properties at a film temperature of 300 K from Table A.4 for outside flow, answer the following questions: Assume the pipe is made out of stainless steel with thermal conductivity of 15W/m/k

(a) What is the Reynolds number of the internal flow? [1]

(b) Using Dittus_Boetler correlation (Eqn 8.60), compute the convective heat transfer coefficient for the internal flow [2]

(c) Using Churchill-Bernstein correlation, compute the convective heat transfer coefficient for the external flow [2]

(c) By doing an energy balance, compute the length of the tube [3]

(d) What is the total heat loss? [1]

In the discussion for fatigue up to this point we have talked about the damaging effect of the number of cycles of loading but we have not discussed about frequency (i.e. how often these loading cycles occur). Which class of materials do you think might be sensitive to the frequency of loading? Provide two physical mechanisms that may affect fatigue life (at least indirectly).

Describe all processes in Otto cycle and Diesel cycle and plot its P-v and T-s diagram respectively

1. How much energy(kJ) is required to vaporize 10 kg of water at 500 kPa?

2. What is the state of water of 150 deg Celcius and 415.7 kPa?

A 150-mm-wide polyamide F-1 flat belt is used to connect a 50-mm-diameter pulley to drive a larger pulley with an angular velocity ratio of 0.5. The center-to-center distance is 2.7 m. The angular speed of the small pulley is 1750 rev/min as it delivers 1.5 kW. The service is such that a service factor Ks of 1.25 is appropriate.

(a) Estimate the centrifugal tension Fc and the torque T.

(b) Estimate the allowable F1, F2, and Fi.

c) Check the friction developmen

An Inertial Measurement Unit (IMU) is an important sensor used in aerial robotics. A typical IMU will contain an accelerometer and a rate gyro. Which of the following information does a robot get from an IMU? (Select all that apply. Choose only quantities that are directly reported by the IMU. Do not include quantities that can be computed from the IMU measurements but cannot be obtained directly. Additional research to find information about IMUs is allowed and encouraged!)

• Position
• Orientation
• Linear velocity
• Angular velocity
• Linear acceleration
• Angular acceleration

Discuss the impact of contemporary robotics locally, regionally and globally

Calculate the expected life of N (# of cycles) in a compression spring with the specifications.

Material: 302 Stainless Steel

End type: closed

Overall Length: 2"

OD: 0.5"

ID: 0.406"

Wire Diameter: 0.047"

Wire Shape: Round

Compressed Lenght: 1.35"

Maximum Load: 3.8 lbs

Rate: 5.85 lbs/in

RoHS: Compliant

a.If you see a white, powdery deposit on a surface, what does it mean to the component?

b.Why does intergranular corrosion reduce the strength of a component and does this

affect airworthiness of an aircraft?

c.What are the problems to detect small, sub-laminar tears on a large aircraft?

a.What are the main types of corrosion concerning aircraft?

b.What is the main difference between corrosion in steel and aluminum?

c.Why is humidity critical for Filiform corrosion?

d.What is meant by stress corrosion and how does it manifest?

a ) The moment of inertia of a rigid body, of mass 40 kg, about an axis through a point at 0.5 m from the mass centre, is 110 kg.m2. What is the moment inertia of the same body about an axis, parallel to the first, at a distance 1.0 m from the mass centre?

[4 marks]

i) A metal hoop, with mass m concentrated along its rim, has radius r, and rolls on a fixed surface without slipping. It has angular velocity ??. What is its kinetic energy? [4 marks]

j) Can a particle (point mass) have angular momentum? Explain your answer.