1. Làm thế nào để đảm bảo tính khả thi của văn bản hành chính ?

Moist air enters a duct at 10 oC, 70% relative humidity, and a volumetric flow rate of 150 m3/min. The mixture is heated as it f

AleksAgata [21]

70% of the chances you a car be a because if you see or 40° 51 5030 minutes and to 70% can be ignored to kinetic energy

7 0

3 years ago

Consider a cubic crystal with the lattice constant a. Complete the parts (a)-(c) below. (a) Sketch the crystallographic planes w

Anna [14]

Answer:

(a) See attachment

(b) The two planes are parallel because the intercepts for plane [220] are X = 0,5 and Y = 0,5 and for plane [110] are X = 1 and Y = 1. When the planes are drawn, they keep the same slope in a 2D plane.

(c) $d = \frac{a}{\sqrt{h^{2} + k^{2} + l^{2}}} = \frac{1}{\sqrt{2}} = 0,707$

Explanation:

(a) To determine the intercepts for an specific set of Miller indices, the reciprocal intercepts are taken as follows:

For [110]

$X = \frac{1}{1} = 1; Y = \frac{1}{1} = 1; Z = \frac{1}{0} = \inf.$

For [220]

$X = \frac{1}{2} = 0,5;Y = \frac{1}{2} = 0,5;Z = \frac{1}{0} = \inf.$

The drawn of the planes is shown in the attachments.

(b) Considering the planes as two sets of 2D straight lines with no intersection to Z axis, then the slope for these two sets are:

For (1,1):

$K_1 = \frac{1}{1} = 1$

For (0.5, 0.5):

$K_2 = \frac{0.5}{0.5} = 1$

As shown above, the slopes are exactly equal, then, the two straight lines are considered parallel and for instance, the two planes are parallel also.

(c) To calculate the d-spacing between these two planes, the distance is calculated as follows:

The Miller indices are already given in the statement. Then, the distance is:

$\frac{1}{d^{2}} = \frac{h^{2} + k^{2} + l^{2}}{a^{2}}$

$d = \frac{a}{\sqrt{h^{2} + k^{2} + l^{2}}} = \frac{1}{\sqrt{2}} = 0,707$

7 0

3 years ago

In a production turning operation, the foreman has decreed that a single pass must be completed on the cylindrical workpiece in

stellarik [79]

Answer:

V = 125.7m/min

Explanation:

Given:

L = 400 mm ≈ 0.4m

D = 150 mm ≈ 0.15m

T = 5 minutes

F = 0.30mm ≈ 0.0003m

To calculate the cutting speed, let's use the formula :

$T = \frac{pi* D * L}{V*F}$

We are to find the speed, V. Let's make it the subject.

$V = \frac{pi* D * L}{F*T}$

Substituting values we have:

$V = \frac{pi* 0.4 * 0.15}{0.0003*5}$

V = 125.68 m/min ≈ 125.7 m/min

Therefore, V = 125.7m/min

7 0

3 years ago

A heat engine uses fuel of energy content 43.1 MJ/kg and produces 17.4 kW of useful power. The heat rejection rate (through the

solmaris [256]

Answer:

a)27.9%

b) $\dot{m}=3.06 \frac{Kg}{h}$

Explanation:

Given that

Fuel energy content = 73.1 MJ/kg

Useful power = 17.4 KW

Heat rejection rate = 44.8 KW

From first law of thermodynamics

Heat addition rate =Heat rejection rate + Power out put

Now by putting the values in the above formula

Heat addition rate = 44.8 + 17.4

Heat addition rate =62.2 KW

We know that efficiency is given as follows

$\eta =\dfrac{power\ out\ put}{Heat\ addition\ rate}$

So

$\eta =\dfrac{17.4}{62.2}$

$\eta =0.279$

So the efficiency is 27.9%.

Now to find usage rate of fuel

Lets take usage rate is $\dot{m}$

Fuel energy content x usage rate of fuel = Heat addition rate

Now by putting the values

$73100\times \dfrac{\dot{m}}{3600}=62.2$

$\dot{m}=3.06 \frac{Kg}{h}$

7 0

3 years ago

For a metal that has an electrical conductivity of 6.1 × 107 (Ω∙m)–1, what is the resistance of a wire that is 4.3 mm in diamete

kotegsom [21]

Answer: (C) 9.14 . 10⁻³ Ω

Explanation:

The resistance of a resistor, is proportional to his length and inversely proportional to his area, being the proportionality constant a property of the material, called resistivity.

The resistivity is defined as the inverse of the electrical conductivity, which depends on the number of charge carriers and the mobility of these carriers, which is different for each material.

So, we can calculate the resistance as follows:

R = 1/σ . L / A, where:

σ = electrical conductivity, l= length of the wire , A = wire cross-section (assumed circular).

Replacing by the values, we can calculate R as follows:

R = 1/6.1. 10⁷ (Ω.m) . 8.1 m. / π (0.0043)² m / 4 = 9.14 . 10⁻³ Ω

7 0

3 years ago