On a cold day during the winter when the relative humidity is ?=70%?=70%, your friend claims that the outside air feels very dry. On a hot day during the summer, the relative humidity is the same, but your friend complains that the air feels very humid. Assuming that your friend isn't just crazy, what explains these statements? Hint: Your discussion should involve relative humidity and the humidity ratio.

When a hydrocarbon burns with 300% of theoretical air, is the adiabatic flame temperature higher than, lower than, or equal to the adiabatic flame temperature when it burns with 100% of theoretical air? Why? Note: You must correctly explain your reasoning to receive credit for this problem.

James would like to invest some money every year-end for 17 years in a money market account earning 5% per year, and then begin to withdraw money from the account to finance his son’s education for 4 years. James thinks that his son should have $35,000 for the first year of college at the start of the 19^th year, and would like to increase that amount by 4% every year to compensate for inflation. How much will James’ first deposit be if he plans to increase the annual deposit by $450? Using Excel formula's. (See 7.15)

First Deposit:

A Carnot engine operates on air between high and low pressures of 3 MPa and 100 kPa with a low temperature of 20°C. For a compression ratio of 15, calculate

the thermal efficiency?,

the MEP?

, and the work output?

A symmetrical wedge with a 12 degree included angle is placed in an air flow which the mach number is 2.3 and the pressure is 60 kPa. If the centerline of the wedge is at an angle of 4 degrees to the direction of the flow, find the pressure difference between the two surfaces of the wedge.

2. What products (at least three different) of biomedical engineering do you expect to encounter in the near future

It is required to lift a skip whose load total is 1kN. Two simple lifting jacks are available both having an effort piston diameter of 10mm and a load piston diameter of 70mm and the load is to be distributed equally between the two.

Calculate:

a) the force ratio and movement ratio of each jack.

b) the pressure within the hydraulic fluid.

I am designing a gas heater and a heat exchanger for a swimming pool. As I am starting with my calculations for the heat exchanger, one of the values that I do not have is the exit temp of the water that enters the swimming pool after the water is heated in the heat exchanger. I know that I need to do a control volume equation to work this out, but I do not know where to go from there. I know that the swimming pool will have some losses like: loss of heat by conduction to the surface that surrounds the pool, loss of heat by evaporation of the water, losses by convection on the free surface of the water. Also just to give more clarity regarding the concept: water will be pumped out of the swimming, sent through a filter, sent through a heat exchanger, and sent back to the swimming pool, what flow rate of water, at what temp, will increase the temp of the swimming pool in a period of time?

If the weight of the contents in a vessel is measured and the density of the material is known, fill in the blanks to describe what steps are required to determine level. Find the ____________________ by dividing weight by ____________________, and then find the ____________________ by dividing ____________________ by the ____________________ of the vessel.

Fill in the blanks?

1. Identify 7-10 primary functions of a common laptop computer.
2. Identify 7-10 primary parts/components of a common laptop computer.
3. Allocate the functions in (a) to the parts/components in (b).

this is related to systems engineering

Discuss the crystal structure of martensite and how this affects its mechanical properties. Identify the advantages and disadvantages of this material, and suitable practical applications. (500 words

1.Explain how hot rolling can be used to manipulate the mechanical properties of metals, with respect to grain structure. (500 words)

Groover/Introduction to Manufacturing Processes

Casting Case Study: Kevin Working in Detroit

Kevin was very excited about his new engineering job near Detroit. He was finally going to be able to contribute to the next generation of automobile design for one of the world’s largest carmakers. Even better, his first project was in development of a new-model hydrogen-fueled sports car. The assignment involved product and process design for three large frame-type structural components for the front half of the car.

Since the parts would eventually be needed in fairly high volume, Kevin figured a net shape process such as casting would be the only economical approach for production. Although cast iron is definitely the best structural material for casting, the demands of the part required the strength and toughness of steel. Kevin’s boss agreed and told Kevin to get started on completing the remaining design details for the parts and getting the plans for production rolling.

As for production, the parts would be cast at their usual foundry, located over the border in Canada. Both to save costs and to maintain control over the geometry, Kevin and his colleagues decided to produce the original patterns for the castings for later shipment to the foundry. They decided to have each pattern machined out of aluminum. One of the key decisions Kevin had to make involved the shrinkage allowance. The direction and uniformity of shrinkage in a casting often depends on the geometry and part features, though in this case he decided they could use a linear shrink rate in all directions.

Kevin’s last task for the new parts was to get an estimate of production cost. For the casting, Kevin consulted the foundry and they told him that the cost mainly depended on two quantities: the heat energy (and thus time) needed to melt the material for each part and the cycle time needed for solidification of each part in the mold. For the first part design, Kevin computed a 3.5 minute melting time based on the heat properties of steel and a 1000 kW electric-arc furnace which operates at 80% efficiency (i.e, 20% of the heat energy from the furnace is lost to the environment). Solidification trials on a simple 2-inch diameter, 4-inch long cylinder took 4.0 minutes, so Kevin calculated a 16 minute time for solidification of his first part based on its volume and surface area.

Question 1

GO TO THE TEXT: Chapter 10 (Groover/Introduction to Manufacturing Processes)

a) What are “no-bake” molds, and how do they compare to green sand molds? How are the expanded polystyrene foam patterns made for the lost foam casting process?

b) Which sand casting defects are due to the release of gases or from moisture in the sand molds?

c) Why is steel so much harder to cast than cast iron?

d) What typical tolerances can Kevin and his colleagues expect out of the sand casting process on their large, steel parts?

e) Although Section 10.3.3 in the textbook shows a more complicated picture of shrinkage, it is still common for practical casting operations to assume a consistent linear shrink rate. If Kevin’s part design calls for a length of 38 mm and a width of 22 mm, calculate the length and width for the pattern to accommodate a linear shrinkage value of 1.8%.

f) Use values from Table 4.1 and 4.2 and equation 10.1 to estimate the part volume corresponding to Kevin’s computation of 3.5 minutes for melting time. Assume the specific heat of the liquid metal steel is 20% smaller than that of the solid, and the heat of fusion is 120 J/g.   The steel melts at 1530ºC and is to be poured at 100ºC higher.

g) Use the part volume from Question 11 and the Solidification time method in Section 10.3.2 (with the results of Kevin’s solidification trials) to estimate the surface area for Kevin’s part corresponding to his 16-minute calculation.

Answer must be typed and presented clearly..

Engineers makes the quality of life easy, discuss.