1. Wastewater from Taman Cenderawasih is treated through a bio tower. These are the data related to the bio tower:

Compute:

1. Ratio of recycled flow to the influent flow
2. Hydraulic loading (m³/m².min)
3. Volume of the medium needed

6.11 Perpetrators of Air Pollutants and CO2 (15 pts)What and how are top three perpetrators of our environment on air pollutants and greenhouse gases? Use a typical coal-fired power plant as example to delineate and environmental impacts in US and the world.

DOT wants to install a traffic signal at a dangerous intersection on US-51. The traffic signal will cost $450,000. Based on historical data, it will eliminate, on average, one fatal accident every 10 years, but will cause 5 additional minor accidents every year. The standard cost assigned to fatal accidents is $12,300,000 and the cost assigned to minor accidents is $160,000 each. At an interest rate of 4% per year, does the B/C ratio justify the cost of the signal? Assume a useful life of 30 years for the traffic signal.

a. Design a concrete mix for construction of a water tank using ACI Committee 211.1-year 1991. The specified design strength of concrete is 30 MPa at 28 days. Standard deviation can be taken as 4 MPa. The specific gravity of fine aggregate and coarse aggregate are 2.65 and 2.7 respectively. The dry rodded bulk density of the coarse aggregate is 1600 kg/m3 and the fineness modulus of fine aggregate is 2.80. Ordinary Portland cement (Type I) will be used. A slump of
50 mm is necessary. Coarse aggregate is found to be absorptive to the extent of 1% and free surface moisture in the sand is found to be 2 percent. Assume any other essential data.
b. If slump value increase to 100 mm, design concrete mixing using the same data.
Compare and discuss the result.

What is an “Alimak lift”?

The pressure drop per unit length of a pipe, dl/dp , for steady, incompressible viscous flow through a straight horizontal pipe depends on the average velocity, V, density of fluid, p, fluid viscosity, µ, pipe diameter, D, and the roughness height, ks. Determine the dimensionless groups that can be used to correlate the data.

Annual emissions of CO₂, CH₄ and N₂O in the USA are estimated to be 6,000 MtCO₂/yr, 36 MtCH₄/yr and 1.75 MtN₂O/yr.

1. What are the impacts of these gases emitted from the USA over a 100-year time horizon?
2. Find the total equivalent CO₂ emissions.

For bending only, determine the lightest-weight W-shape
to carry a uniform dead load of 4.5 kip/ft plus the
beam self-weight and a live load of 3.5 kip/ft on a simple
span of 24 ft. Consider only the limit state of yielding and
use A992 steel. Design by (a) LRFD

At the end of a sporting event, vehicles begin leaving a parking lot at λ(t) = 12 − 0.25t and vehicles are processed at μ(t) = 2.5 + 0.5t [t is in minutes and λ(t) and μ(t) are in vehicles per minute]. Assuming D/D/1 queuing, determine the total vehicle delay, longest queue, and the wait time of the 50th vehicle to arrive assuming first-in-first-out and D/D/1 queuing.

Answer:  total delay=1016.15 veh-min, Delay 50th veh=5.64 min, Max Q=60.167 veh

What do you believe is a reasonable availability or utilization rate (the percentage of your time that is charged to billable projects) is for a staff engineer one month after the engineer starts working for the company after just graduating from college?

1. 6 Months?
2. 1 Year?
3. Explain the reasoning for your responses

A factory disposes 1.1 m³/s of treated industrial wastewater into a river. The wastewater has an ultimate biochemical oxygen demand of 25 mg/L and dissolved oxygen of 2 mg/L. Just upstream of the wastewater outfall, the river has a flow rate of 10 m³/s, ultimate biochemical oxygen demand of 6 mg/L, and oxygen deficit of 2 mg/L. At the river temperature, the saturation concentration of dissolved oxygen is 9 mg/L. The deoxygenation coefficient is 0.19 d^-1 and reaeration coefficient is 0.11 d^-1. The velocity of the river is 0.4 m/s.

(a) What is the ultimate biochemical oxygen demand (mg/l) immediately downstream of the outfall?

(b) What is the dissolved oxygen (mg/L) immediately downstream of the outfall?

(c) What is the oxygen deficit (mg/L) 97 km downstream of the discharge point?

(d) What is the maximum oxygen deficit (mg/l) along the river, and where does it occur (km)?

A rectangular beam of base b = 50 mm and height h = 25 mm is bent into a curved beam of 100 mm radius (R), and is subjected to a bending moment M of 500 N-m. Determine: The largest tensile and compressive stresses, how do the above values compare with the ones for straight beam?

5. Name the two types of fatigue cracking and the critical pavement locations.

Type:                              Critical location:    

Type:                                Critical location:

6. Name the causes typically associated with both types of fatigue cracking.

First Type:                             Causes:

Second Type:                         Causes:          

7. Name the type of loading typically used in the laboratory for evaluating:

Thin pavements        :          

Thick pavements       :          

8. In a typical conventional asphalt concrete pavement, keeping all other factors constant, (FILL IN THE BLANKS)

1. Increasing the HMA thickness typically                        fatigue cracking.

2. Increasing the HMA modulus typically                         fatigue cracking.

3. Increasing the wheel load typically                                fatigue cracking.

4. Increasing the tire pressure typically                             fatigue cracking.

17. List three computer programs that may be used to calculate pavement responses in flexible pavements.

18. In terms of fatigue cracking, a damage index, D, of 1.0 means that the roadway

19. List the three types of distortion.

20. __   ___           and __ _     __ are two mechanisms that cause rutting.