Discuss the effect of (i) grain size and (ii) phases amounts on the mechanical properties of the steel metal

An aircraft is in level flight at airspeed v(t) m/s with thrust T(t) N at cruising altitude. Suppose that at v0 = 250 m/s, the aerodynamic drag experienced by the aircraft at this altitude is:

Fd(v) = 0.25v 2 . (1)

Then, an extremely simplified model relating v(t) to T(t) is:

mv˙(t) + Fd(v(t)) = T(t), (2)

where m = 25000 kg. Assume v(t) is always positive.

Question 1. Linearize (2) at v0 = 250 m/s, and an appropriate nominal thrust T0. That is, create a new linear system model ˙δv + aδv = bδT that is accurate for small perturbations δv(t) = v(t) − v0, δT = T(t) − T0.

Question 2. Suppose we want the aircraft to fly at v0 = 250 m/s. However, precise modelling of drag is very difficult. Suppose in reality the dynamics are slightly different:

mv˙(t) + 0.23v(t) 2 = T(t). (3)

To control v(t) to be close to the reference 250m/s, you try using a proportional controller to control the thrust:

T(t) = T0 + k(v0 − v(t)), (4) with k = 100.

Here T0 is the value calculated in Question 1, but the controller is applied to the true dynamics (3). Find the final final value of v in: (a) open loop (i.e. just apply T(t) = T0), and (b) closed loop (using (4)). You may need to solve a quadratic equation. Recall that v(t) is assumed to be positive. Which one is better?

A 6 inch diameter water main in your town has become very rough due to rust and corrosion. It has been suggested that the flowrate through this pipe can be increased by inserting a smooth plastic liner into the pipe. Although the new diameter will be smaller, the pipe will be smoother. Will such a procedure produce a greater flowrate? List all assumptions and all calculations.

IMPORTANT NOTE: Please have the answer complete, CLEAR and computer generated!!

Air enters a 30-cm-diameter cooling section at 1 atm, 35 C, and 60 percent relative humidity at 120 m/min. The air is cooled by passing it over a cooling coil through which cold water flows. The water experiences a temperature rise of 8 C. The air leaves the cooling section saturated at 20 C.

(a) Determine the rate of heat transfer. Round your answer to the nearest tenth.

     Q_out = _____ kJ/min

(b) Determine the mass flow rate of the water. Round your answer to the nearest hundredth

     m_{cooling water} = _____ kg/min

(c) Determine the exit velocity of the airstream. Round your answer to the nearest ones place.

     V₂ = _____ m/min

Considering only conductive heat losses, calculate the heating load in BTU/H for a home constructed as follows:

walls: 2 inch hardwood planks, plus 1/2 inch lapped wood siding and 1/2 sheetrock (drywall) inside.

roof: flat, 1 inch plywood finished with asbestos shingles, with 3.5 inches fiberglass insulation.

floor: 25/32 inch wood subfloor with 3/4 inch hardwood finish, over unheated crawl space

windows: single pain glass, covering 25% of the wall area

House size is 28 ft x 40 ft x 10 ft high

Assume the home is maintained 40F warmer than outside, and 10F warmer than the crawlspace.

Assume your answer in units of BTU/hr

In a delivery line for carbontetrachloride at the constant flow rate of 4 X 10^(-5) m3/s, the first 1000 mm long section is of 20 mm inside diameter smooth pipe followed by another 1000 mm long section of 50 mm inside diameter smooth pipe as shown in the following figure. Estimate the pressure drop over the entire length of delivery line. Neglect the minor losses due to sudden enlargement of pipe diameter.

Data: For carbon tetrachloride, Viscosity = 10^(-3) Pa.sec and density = 1500 kg/m3 For laminar flow, consider fanning friction factor, f = 16/Re
For transitional-turbulent flow, f = 0.079Re^(-0.25)

Air is compressed adiabatically in a piston–cylinder assembly from 1 bar, 300 K to 4 bar, 600 K. The air can be modeled as an ideal gas and kinetic and potential energy effects are negligible. Determine the amount of entropy produced, in kJ/K per kg of air, for the compression. What is the minimum theoretical work input, in kJ per kg of air, for an adiabatic compression from the given initial state to a final pressure of 4 bar? Note that work is positive into the compressor.

A conduit carrying water vapor has one inlet and two exits. At the inlet, the velocity 25 m/s, the pressure is 4 bar and the temperature is 350 Celsius. The area at the inlet is 0.2 m^2 . At both the exits, the temperature and pressure are 300 Celsius and 3 bar respectively. The volumetric flow rate is identical at the two exits. Assuming steady-state conditions, calculate the volumetric flow rate at the exits.

Three phase voltage is spaced? is it 120 degrees apart?

A three phase 30 hp 460 volt 60 hz, 1770 rpm design B induction motor with class F insulation and service factor of 1.0 is operating at rated shaft load in a 40 degree C environment and has an expected 20 yr life. A maintenance check shows line to line voltages to be 449.2 V, 431.3 V and 462.4 volts. The percent unbalanced voltage for this motor is:

the expected temperature rise equals?

The expected insulation life equals?

the rerating in horsepower equals?

Energy flows out of the system in form of a heat in an internally reversible process. What happened to he entropy of the system? Explain

Energy flows out of the system in form of a heat in an internally reversible process. What happened to he entropy of the system? Explain

Consider the design of a wastewater treatment plant (WWTP) for a community with average
daily and peak hourly wastewater design flows of 7570 m3/day and 18925 m3/day. The raw
sewage has an average of 240 mg/L BOD5 and 270 mg/L of suspended solids.

(a) Assume that the primary sedimentation process removes 55% of the suspended solids and
35% of the BOD5 of the raw sewage. Determine the SS and BOD5 concentrations in the
primary sedimentation effluent flow. (1 mark)

The primary effluent is treated by two parallel trains of the complete-mix activated sludge
process. Assume with the average flow conditions and the performance of primary
sedimentation achieved as above. Given the following parameters required for the activated
sludge process:

· Effluent BOD5 (S): 8 mg/L
· Observed biomass yield (Y): 0.55 kg biomass / kg BOD
· Endogenous decay rate (b) = 0.04 /day
· Solids retention time: 8 days
· MLVSS concentration in the aeration tank: 3000 mg/L
· Waste and recycle solids concentration: 12,000 mg/L

By using the formulas shown in appendix, determine the following:
(b) Aeration tank volume (m3).
(c) Mass flow rate of wasted sludge (kg/day). (1 mark)
(d) Volumetric flow rate of wasted sludge (m3/day). (1 mark)
(e) Return (recycle) flow rate (m3/day).
(f) Volumetric BOD loading to the aeration tank (kg BOD/m3.day). (1 mark)
(g) Food to microorganisms (F/M) ratio for the aeration tank (kg BOD day/kg MLVSS). (1 mark)
(h) Design hydraulic retention time (hr). (1 mark)

1. A plant is located at an altitude where the atmospheric pressure head is 31 ft of water and the vapor pressure is 9.34 psi. The pump is placed 10 ft below the water tank with a total suction pipe length of 25 ft, pipe diameter 3 in., and friction coefficient 0.02. Assuming the given atmospheric pressure in the tank (where z1 = 10 ft and negligible velocity) and if the flowrate provided is 180 gpm, determine the available NPSH (ft). Neglect minor losses. ans 17.4 ft