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Drupady [299]
3 years ago
6

Explain the purpose of the checkpoint mechanism. How often should checkpoints be performed?How does the frequency of checkpoints

affect:
System performance when no failure occurs?
The time it takes to recover from a system crash?
The time it takes to recover from a disk crash?
Engineering
1 answer:
Olegator [25]3 years ago
3 0

Explanation:

Answer:

1) Check point mechanism is a system, point or mechanism within the database management system that allows for data, information, transactions and general logs passed through the system be retrieved and stored into a separate storage system and talking about how often the check point should be performed, it is advised that checkpoint should be done as often as possible because the more often the checkpoints is done, the lower the probability that obsolete data will be updated or retrieved during the checkpoint process.

How does the frequency of check point affects system performance when no failure occurs?

Answer: When failure does not occur, the process of checkpoint mechanism have only succeeded in accruing unnecessary cost of performing the process which at this time would have been necessary.

How does the frequency of check point affects the time it takes to recover from a system crash ?

Answer: It is important to note that the purpose of a check point mechanism in the first place is for us to be able to recover our data in the database before a time when the database became corrupt. So if we constantly run the process of check point mechanism, it will drastically reduce the time it takes to recover from a system crash because we would have previously detected obsolete data and updated the system before the crash.

How does the frequency of check point affects the time it takes to recover from a disk crash?

Answer: This can also be related to the same time of recovery as that of the system crash.  We can substitute the answer for time to recover from a system crash for that of a disc crash also. The only difference here is that it applies to a disc.

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SCORPION-xisa [38]

Answer:

F_{thrust} ≅ 111 KN

Explanation:

Given that;

A medium-sized jet has a 3.8-mm-diameter i.e diameter (d) = 3.8

mass = 85,000 kg

drag co-efficient (C) = 0.37

(velocity (v)= 230 m/s

density (ρ) = 1.0 kg/m³

To calculate the thrust; we need to determine the relation of the drag force; which is given as:

F_{drag} = \frac{1}{2} × CρAv²

where;

ρ = density of air wind.

C = drag co-efficient

A = Area of the jet

v = velocity of the jet

From the question, we can deduce that the jet is in motion with a constant speed; as such: the net force acting on the jet in the air = 0

SO, F_{drag}-F_{thrust} = 0

We can as well say:

F_{drag}= F_{thrust}

We can now replace F_{thrust} with F_{drag} in the above equation.

Therefore, F_{thrust} = \frac{1}{2} × CρAv²

The A which stands as the area of the jet is given by the formula:

A=\frac{\pi d^2}{4}

We can now have a new equation after substituting our A into the previous equation as:

F_{thrust} = \frac{1}{2} × Cρ (\frac{\pi d^2}{4})v^2

Substituting our data from above; we have:

F_{thrust} = \frac{1}{2} × (0.37)(1.0kg/m^3)(\frac{\pi(3.8m)^2 }{4})(230m/s)^2

F_{thrust} = \frac{1}{8}   (0.37)(1.0kg/m^3)({\pi(3.8m)^2 })(230m/s)^2

F_{thrust} = 110,990N

F_{thrust}  in N (newton) to KN (kilo-newton) will be:

F_{thrust} = (110,990N)*\frac{1KN}{1,000N}

F_{thrust} = 110.990 KN

F_{thrust} ≅ 111 KN

In conclusion, the jet engine needed to provide 111 KN thrust in order to cruise at 230 m/s at an altitude where the air density is 1.0 kg/m³.

5 0
3 years ago
Tech a says that the weight of the flywheel smoothest out the engines power pulses. Tech B says that the flexplate and torque co
lakkis [162]

Answer:

both statement is correct

Explanation:

Flywheel engine uses to reduce fluctuations.

And                                                                

FlexPlate is a metal disk that connects the output from the engine to the input of the torque converter. This will replace the flywheel

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4 0
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mafiozo [28]

Answer:

\frac{2}{16}  = \frac{4}{32} in thirty seconds.

Explanation:

one thirty second is one part out of 32 equal section . It is used to describe amounts accurately.

\frac{2}{16} can be easily expressed as \frac{4}{32}

3 0
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sertanlavr [38]
The answer would be:
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pickupchik [31]

Answer:

b). Occurs at the outer surface of the shaft

Explanation:

We know from shear stress and torque relationship, we know that

\frac{T}{J}= \frac{\tau }{r}

where, T = torque

            J = polar moment of inertia of shaft

            τ = torsional shear stress

             r = raduis of the shaft

Therefore from the above relation we see that

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Thus torsional shear stress, τ is directly proportional to the radius,r of the shaft.

When r= 0, then τ = 0

and when r = R , τ is maximum

Thus, torsional shear stress is maximum at the outer surface of the shaft.

4 0
4 years ago
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