Engineering Answers

1. Explain why is important to identify hazards/dangers at the workplace. 2. Explain the implications if hazards/dangers are ignored in the workplace. 3. Mention common examples of accidents in a chemical plant or processing plant and how can they be avoided. 

The three major steps involved in Mineral Processing namely: Crushing, grinding and flotation. Please discuss the importance of each during mineral processing. 

 Discuss the importance of sustainability in mineral processing industry or business.

Compute the drying power Ea and the relative evaporation Er of an area covered with grass of Z. = 2 cm, and that of an adjacent area covered with trees of Z, = 70cm. Given that wind velocity U = 2.5 m/sec, Tair = 8°C, relative humidity = 0.3, Pair = 1.3 kg/m”, pw = 1000 kg/m”, Patm = 1013mb, Z = 2m, and net radiation Q = 90 W/m². Why the Ed of trees is higher than that of grass?

Complex poles and zeros. Sketch the root locus with respect to K for the equation 1 + KL(s) = 0 and the listed choices for L(s). Be sure to give the asymptotes and the arrival and departure angles at any complex zero or pole. After completing each hand sketch, verify your results using Matlab. Turn in your hand sketches and the Matlab results on the same scales

A slightly compressible oil is flowing in a volumetric, homogeneous reservoir. The oil has a viscosity of 2 cp, compressibility of 5 x 10-5psi -1 and formation volume factor of 1 RB/STB. The reservoir is represented by a three-gridblock system as shown: T The dimensions and the properties of all gridblocks are Ax=200 ft, Ay=100 ft, Az=20 ft, kx= 100 mD, and p=0.20. The initial reservoir pressure is 3,000 psia. The well in gridblock 3 is produced so that the well block pressure is maintained at 1,500 psia for all time >0. All the boundaries are closed. Find the pressure of gridblocks 1 and 2 at t=10 days with the implicit finite difference formulation and the time step At=10 days.

Find inverse Laplace transform of following:

1.F(s)=(S+1) / ((S+2)^2 (S+2S+4)^2 )

A 50 Hz, 885 V/88.5 V transformer is used for stepping down voltage. Its HV winding resistance and reactance are 90 ohms and 85 ohms respectively and its LV winding resistance and reactance are 9 ohms and 8.5 ohms respectively. Its core-loss as measured from the primary side = 6 W. The load connected to it = 6 + j7 ohms.

What is the value of its core-loss resistance in k.ohms when looked from the primary side?

What is its core-loss in W when looked from the secondary side?

What is the magnitude of the current that flows through the given load in A?

What is the power consumed in the load in W?

What is the magnitude of the current that will be flowing into the primary winding in A if the excitation current is neglected?

A 205 V, 19 kW dc shunt motor has a 3 step (3 resistance) starter that restricts the starting armature current between its rated value and some K times this rated value. This motor is 69 % efficient at rated conditions and its field resistance = 205 ohms. The starting resistance in each step is 6 times its armature resistance.

What is the maximum starting armature current in A?

What is total resistance of the starter in Ohms?

What is the back EMF in Volts, when the starter is just put in 2nd step? Assume that the transition from 1st to 2nd step is instantaneous.

What is the back EMF in Volts by the end of the 2nd step?

What is the back EMF of this motor in Volts under rated conditions?

a) Simplify the following Boolean expression using three variable maps

     F(x, y, z) = x y z + x’y’ z + x y’ z’

b)Simplify the following Boolean expression using four variable maps:

       F(w,x, y, z) = Σ(0,1,4,5,6,7,8,9)

A column with one end pinned and another end fixed is made of carbon steel AISI 1020. The column is hollow round bar with internal radius of 20.0 mm, thickness of 3.0 mm and length of 2000.0 mm. Determine a) whether the columns will buckle inelasticity or elastically. (4 marks) b) the buckling stress if the column is subjected with 80N of axial force (8 marks) c) the critical buckling load for the column. (8 marks)