A brief overview of Prestressed concrete investment in Korea and percentage of application

no more than 500words

A brief overview of Prestressed concrete investment in North America and percentage of application

no more than 500words

An expansion valve in a refrigeration cycle throttles R134a from 1.2MPa saturated liquid to 0.32MPa. What is the specific volume at the exit of the expansion valve in unit of m3/kg. Round the result to 4 decimal places.

Design a speed-increasing gear train with a speed ratio of SPR defined below:

Speed ration = 13

The gear train does not need to be reverted. Specify the appropriate numbers of teeth to minimize the gearbox size while avoiding the interference problem in the teeth. Perform the analysis subject to the following constraints:

A) Use a 20° pressure angle and match SPR exactly.

B) Use a 25° pressure angle and match SPR exactly.

C) Use a 20° pressure angle and for a speed ratio within 1% of SPR.

An ideal vapor compression refrigeration cycle using r134a as the refrigerant is being used to cool a house. It provides 3 refrigeration tons ≈ 10.5kW of cooling (heat removal from the house air). The refrigerant in the evaporator operates at 400kPa while in the condenser it is at 1000kPa. Treat the surroundings as a thermal reservoir at 33◦C and the air in the house as a thermal reservoir at 19◦C. All reservoirs are at 100kPa.

1. What is the COPr of this cycle?

2. How fast is exergy destroyed (kJ/s) in each process (evaporator, condenser, throttle, compressor)?

3. Which process has the lowest second law efficiency?

4. What is the rate of exergy destruction (kJ/s) for the cycle?

Consider the flow of a liquid metal past a flat plate (Pr << 1). We have shown that for a constant wall teemperature, T_o, the Nusselt number is given by Nu = 0.564*(Re^1/2)*(Pr^1/2). Show that if the surface is not a constant temperature, but is instead providing a constant heat flux, that the Nusselt number becomes Nu = 0.886*(Re^1/2)*(Pr^1/2). Start with the following expression for the temperature profile within a semi-infinite body with a constant heat flux boundary condition T - T_o = (q_s / k)[ ((4*alpha*t) / pi)^1/2 * exp(-x^2 / (4*alpha*t)) - x*erfc( x / (4*alpha*t)^1/2 ) ].

Explain how confinement affects detonation properties, specifically in non-ideal high explosives.(Using Annual Review of Fluid Mechanics
High Explosive Detonation–Confiner Interactions for reference).

examine the structure of the materials management processes for these types of items. Specifically, address the following:

What are some necessary considerations when designing a materials management process for bulk and long-lead time items?

How should a project schedule deal with these types of items?

Steam enters an adiabatic turbine at 500C and 4.0MPa and 80m/s. The steam leaves the turbine as saturated liquid-vapor mixture at 30kPa, quality of 92% and 50m/s. The mass flow rate of steam through the turbine is 12kg/s.

(10 pts) Determine change in kinetic energy

(10 pts) Determine the rate of work (power) done by the steam in the turbine, in kW (neglect potential energy change).

(10 pts) Determine the flow area at the entrance to the turbine, in m². (Hint: use mass flow rate definition).

A tube with a diameter of 6.45 mm was placed in a liquid with a density of 998 kg / m3 and it was observed that the liquid increased by 1.44 mm in the tube. Find the surface tension of the fluid [N / m] by taking the contact angle 15 ° between the liquid and the tube surface.

Steam is compressed by an adiabatic compressor from 3 bar and 160°C to 10 bar and 350°C at a rate of 1.30 kg/s. The power input to the compressor is

You drop a 2 kg rock from the edge of a cliff. How much kinetic energy does the rock have when it has dropped 5 meters down? What speed does it have? [Enter your result for KE in the first answer box and your result for the speed in the second one.]

The following true stresses produce the corresponding true plastic strains for a brass alloy:

What true stress is necessary to produce a true plastic strain of 0.25?

11. Draw a schematic of a swash plate axial piston pump with inclined pistons. Explain briefly its function and give an expression for its geometric volume.