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3 years ago

10

Why is it important to have knowledge on abbreviations, sign and symbols in masonry servicing job in the construction business s

ector?

1 answer:

marta [7]3 years ago

5 0

Maybe To know short cuts on the long run. And it is a way of coding

You might be interested in

An automotive fuel cell consumes fuel at a rate of 28m3/h and delivers 80kW of power to the wheels. If the hydrogen fuel has a h

EastWind [94]

Answer:

The efficiency of this fuel cell is 80.69 percent.

Explanation:

From Physics we define the efficiency of the automotive fuel cell ( $\eta$ ), dimensionless, as:

$\eta = \frac{\dot W_{out}}{\dot W_{in}}$ (Eq. 1)

Where:

$\dot W_{in}$ - Maximum power possible from hydrogen flow, measured in kilowatts.

$\dot W_{out}$ - Output power of the automotive fuel cell, measured in kilowatts.

The maximum power possible from hydrogen flow is:

$\dot W_{in} = \dot V\cdot \rho \cdot L_{c}$ (Eq. 2)

Where:

$\dot V$ - Volume flow rate, measured in cubic meters per second.

$\rho$ - Density of hydrogen, measured in kilograms per cubic meter.

$L_{c}$ - Heating value of hydrogen, measured in kilojoules per kilogram.

If we know that $\dot V = \frac{28}{3600}\,\frac{m^{3}}{s}$ , $\rho = 0.0899\,\frac{kg}{m^{3}}$ , $L_{c} = 141790\,\frac{kJ}{kg}$ and $\dot W_{out} = 80\,kW$ , then the efficiency of this fuel cell is:

(Eq. 1)

$\dot W_{in} = \left(\frac{28}{3600}\,\frac{m^{3}}{s}\right)\cdot \left(0.0899\,\frac{kg}{m^{3}} \right)\cdot \left(141790\,\frac{kJ}{kg} \right)$

$\dot W_{in} = 99.143\,kW$

(Eq. 2)

$\eta = \frac{80\,kW}{99.143\,kW}$

$\eta = 0.807$

The efficiency of this fuel cell is 80.69 percent.

3 0

3 years ago

Let m be an integer in the set {0,1,2,3,4,5,6,7,8, 9}, and consider the following problem: determine m by asking 3-way questions

kupik [55]

Answer:

Take any algorithm if that algorithm solves this problem it can be represented as a ternary decision tree. Therefore each question has at most three answers.

There are ten possible verdicts, the height of such kind of tree should satisfy

ℎ >= ⌈log3(10)⌉ = 3

Hence no such algorithm can ask less than three questions in the worst case.

---

b)

Each and every internal node represents a question asking whether m belongs to one of three possible subset of {0, 1, 2, 3, 4, 5, 6, 7, 8, 9} or not

For example 0123|456|789 represented the questionDoes “m: belongs to {0, 1, 2, 3}, to {4, 5, 6}, or to {7, 8, 9}?"

Verdicts are placed in brackets "[ ]"

Explanation:

decision tree is attached below

5 0

3 years ago

2.11 Consider a 400 mm × 400 mm window in an aircraft. For a temperature difference of 90°C from the inner to the outer surface

alexandr402 [8]

Answer:

The heat loss rate through one of the windows made of polycarbonate is 252W. If the window is made of aerogel, the heat loss rate is 16.8W. If the window is made of soda-lime glass, the heat loss rate is 1190.4W.

The cost associated with the heat loss through the windows for an 8-hour flight is:

For aerogel windows: $17.472 (most efficient)

For polycarbonate windows: $262.08

For soda-lime glass windows: $1,238.016 (least efficient)

Explanation:

To calculate the heat loss rate through the window, we can use a model of heat transmission by conduction throw flat wall. Using unidimensional Fourier law:

$\frac{dQ}{dt}=\dot Q =-kS\nabla \vec{T}$

In this case:

$\dot Q =k\frac{S}{L} \Delta T$

If we replace the data provided by the problem we get the heat loss rate through one of the windows of each material (we only have to change the thermal conductivities).

To obtain the thermal conductivity of the soda-lime glass we use the graphic attached to this answer (In this case for soda-lime glass k₃₀₀=0.992w/m·K).

To calculate the cost associated with the heat loss through the windows for an 8-hour flight we use this formula (using the heat loss rate calculated in each case):

$Cost=C_{hc}\cdot \dot Q \cdot t \cdot n=1\frac{\$}{Kwh} \cdot \dot Q \cdot 8h \cdot 130$

6 0

3 years ago

"Water is flowing in a metal pipe. The pipe OD (outside diameter) is 61 cm. The pipe length is 120 m. The pipe wall thickness is

Katarina [22]

Answer:

Total wight =640.7927 KN

Explanation:

Given that

do= 61 cm

L =120

t= 0.9 cm

That is why inner diameter of the pipe

di= 61 - 2 x 0.9 cm

di=59.2 cm

Water density ,ρ = 1 kg/L = 1000 kg/m³

Weight of the pipe ,wt = 2500 N/m

wt = 2500 x 120 N = 300,000 N

The wight of the water

wt ' = ρ V g

$wt'=1000\times \dfrac{\pi}{4}\times (0.61^2-0.0592^2)\times 9.81\times 120 N$

wt'=340792.47 N

That is why total wight

Total wight = wt + wt'

Total wight =300,000+ 340792.47 N

Total wight =640,792.47 N

Total wight =640.7927 KN

7 0

4 years ago

Omplete the following program: [0.5 X 4 = 2]

borishaifa [10]

I’m confused on this one

4 0

3 years ago