As the dimensions of an object reduces, why does the surface forces become more dominant as compared to the body forces? For example a 1 in^3 of SiO2 will drop to the ground when you release it from your habd, but a grain of sand "could" stick to your fingers when released from your hand under the same conditions.

In looking at the thermoelectric effect in silicon crystalline nanowires, why does DECREASING NANOWIRE DIMENSION AND INCREASING WIRE SURFACE ROUGHNESS increase the thermoelectric figure of merit?

Two parts of a machine are held together by eight equally-spaced M6x1.0 grade 5.8 bolts that are unifomly tightened to provide a total inital clamping force of 44 kN. Each bolt has a proof stress of 380 MPa, and a threaded area of 20.1 mm^2. The elasticities are such that the member stiffness is four times as high as the member stiffness.

b) You have determined that assembly procedure can reliably set the initial clamping force to within plus or minus 20% of the nominal value. What do you recommend as a safe working load if you require a factor of safety of 2.5 against any failures?

Problem1. A piston cylinder device containing 0.5 kg of water has initial volume of 0.5L. The device starts and goes through a Carnot cycle and generates 500.3 kJ work. If the maximum temperature that water will reach is 1.5 times the minimum temperature of water and during heat rejection process, water goes from saturated vapor to saturated liquid phase. Find: 1. QH & QL for this cycle (10 points). 2. TH & TL for this cycle (10 points). 3. Maximum and minimum pressures that the cycle will reach (20 points). 4. Show this process on a T-v diagram and label temperature, pressures and specific volumes. (To get full points, your states, and your processes should be accurately placed in relation to isobaric lines and vapor dome) (10 points). 5. The expansion and compression of water in this device are quasi-equilibrium processes, EXPLAIN why this process delivers the highest amount of work (5 points). 6. Find the pressure at remaining state(s) (Bonus 5 points)

R-134a flows in a horizontal 8 mm diameter circular tube. The mass flux is 400 kg/m2s, the entering quality is 0.0, and the existing quality is 0.8. The tube length is 3 m. Assuming a constant saturation temperature of 20°C, plot the variation of hTP as a function of x.

Differentiate continuous and project type production

Consider the TOYCO model given below:

TOYCO Primal:

max z=3x1+2x2+5x3

s.t.

x1 + 2x2 + x3 ? 430 (Operation 1)

3x1 + 2x3 ? 460 (Operation 2)

x1 + 4x2 ? 420 (Opeartion 3 )

x1, x2, x3 ?0

Optimal tableau is given below:

a) Suppose that TOYCO wants to change the capacities of the three operations as bT = [460, 500, 400](the new right-hand-side vector). Use the post optimality analysis to determine the optimum solution.

b) Suppose that TOYCO adds a fourth operation with the operation times of 4, 1, and 2 minutes for product 1, 2, and 3 respectively. Assume that the capacity of the fourth operation is 548 minutes. Determine the new optimal solution for this case.

c) Suppose the objective function is changed to z = 3x1 + 6x2 + x3. If the solution changes, use the post-optimal analysis to find the new solution.

d) Suppose TOYCO wants to produce toy planes. It requires 3,2,4 minutes respectively on operations 1,2, and 3. Determine the optimal solution when the revenue per unit for toy planes is $10.

List and describe the sequence of events for injection molding.

Introduce current technological challenges with respect to the engineering design of vision systems for drones and autonomous vehicles. Also, present the underlying physical and engineering principle of autonomous vision systems. How can the existing drone detector technology be improved further? (For instance, you may relate to class material with emphasis on deep learning, neural network, cognition vision features, neuromorphic vision, bioinspired vision and other.)

How would one machine a typical shaft and shaft sleeve? Describe the sequence of operations. What are the manufacturing process used? Please answer with detail.

b. Conduct an analysis for a gas turbine combustor using Propane, C3H8, you can assume the product outlet temperature is 1500 K and the air inlet temperature is 650 K on a standard day (25 C) and the fuel enters at ambient temperature.

List the parameters that influence temperature during metal cutting, and explain why and how?

A thin airfoil can be approximated as a flat plate. The airfoil is set at an angle of 10° to an air flow with Mach 2, a temperature of –50°C, and a pressure of 50 kPa. Using linearized theory, find the pressures on the upper and lower surfaces of this wing.

A small research vehicle with a length of 4 ft travels at Mach 15 at altitudes of 100,000 and 250,000 ft. Determine whether, at these two altitudes, the missile is in the continuum, slip, transition, or free molecular flow regimes. It can be assumed that at an altitude of 100,000 ft, the pressure, temperature, and viscosity are 22 psf, 340 R, and 96 × 10?7 lbm/ft-s, respectively, whereas at an altitude of 250,000 ft, they are 0.11 psf, 450 R, and 100 × 10?7 lbm/ft-s, respectively

Consider a compressor in which air enters at 1 bar, 27°C and exits at 3.5 bar, 127°C. The work required is 127 kJ/kg of air flowing through the compressor. Heat transfer between the compressor and environment occurs at 27°C.

Determine

(a) the heat transfer, in kJ/kg

(b) the entropy generation rate, in kJ/kg.K, for the compressor as a control volume

(c) the entropy generation rate, in kJ/kg.K, for the compressor and the surrounding environment

(d) the entropy generation rate, in kJ/kg.K, for the environment alone.