Think and Answer Assignments: Minicase IV Household Wireless page....

Q)Your sister is building a new two story house which measures 50 feet long by 30 feet wide and wants to network her family’s three computers together. She and her husband are both consultants and work out of their home in the evenings and a few days a month.  Each has a separate office with a computer, plus a laptop from the office that they occasionally use. The kids also have a computer in their playroom. They have several options for networking their home:

a) Wire the two offices and playroom with Ethernet cat5e and put in a 100Base-T switch.

b) Install one Wi-Fi access point ($85) and put Wi-Fi cards in the three computers (the laptops already have Wi-Fi)

c) Any combination of these options

There are many possible solutions to this problem.  What would you recommend, considering their current hardware configuration as well as potential expansion? Justify your recommendation.           

Sol:

The best possible solution is to go for installation of Wi-Fi access points followed by installation of Wi-Fi cards for the desktop computers. Anyways laptops will definitely have Wi-Fi inbuilt so there is no need for separate installation of the cards in laptops. The reason behind this is looking at the future definitely the desktops are getting replaced by laptops. Also laptops are portable, which means we can carry them any where we need but if they are connected to some network cables then we will not be able to access the network wherever we carry the laptops. Also in case of desktops if we place it in 1st floor but tomorrow we need it in the last floor then there is need to work on the network connectivity in it only labor is involved in shifting but network connectivity is always there since it is independent of the location within the office campus or two story house limits. Hence the recommendation here is to go for Wi-Fi connection.

Write-Ups Assignment Help: What is a little-know secret to the profitability of Amazon.com?

The below are few of the topics on which the write-ups of 300 to 500 words are expected:

1) What is a little-know secret to the profitability of Amazon.com?

2) Which of these characterized the strategies is the early days (and somewhat, still today) of electronic commerce?

3)Q)“Words carry the message. They would carry the same meanings with or without paragraphing. Therefore, paragraphing has no effect on communication.” Discuss your view of this statement and provide an example which supports your analysis. 

4)What is access matrix? For what purpose is access matrix used in general purpose OS?

4)Many people feel that the American government is out of touch with its public. Look at the branches of government and analyze this statement. 

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Write-Ups Assignment Help: JIT logistics/supply chain management for what...

Q) JIT logistics/supply chain management for what (now defunct) America automaker.

Sol:

JUST-IN-TIME LOGISTICS SUPPORT IS USED FOR THE AUTOMOBILE INDUSTRY since JIT drastically reduces the investment as well as also the total cost of the operation. In the early 1970s the United States automobile industry realized that the advantage of adopting the JIT would bring the US automakers where they were carrying $775 worth of the work in the process inventory for each of the car they built, but the Japanese carried only $150 of the amount. The only very existence of the Unites states auto industry which depended on the adopting of the JIT philosophy. Very efficient way of transportation methods were one of the critical to the effective JIT process.

Key issues of the transportation before the JIT include plant locations, were the role of the transportation along with the deregulation as well as the transportation regulation. The placement of the plants also changed as a solution of the implementation of the JIT.

Homework Help: What is the speed of the block when the spring has been compressed...

A block with a mass of 0.148kg is traveling at 8.4m/s on a horizontal,frictionless surface when it hits a spring with a spring constant of 722 N/m. What is the compression of the spring when the block has slowed to 3.9 m/s?What is the speed of the block when the spring has been compressed by 0.049m?

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Physics Homework Help: Compare the kinetic energy of an...

Q) Compare the kinetic energy of an 900 kg car travelling at 30 m/s, and a 1,800 kg car at the same speed.

 Sol:

Kinetic energy is given by, KE = 1/2mv²

Where ‘m’ is the mass, ‘v’ is the velocity.

Case1:

Given m=900kg, v=30m/s

(KE) ₁= 0.5*900*30²=405000Joules

Case2:

Given m=1800kg,v=30m/s

(KE) ₂= 0.5*1800*30²=810000Joules

Therefore, (KE) ₂ = 2(KE) ₁

Homework Help: What is the gauge pressure in the tire after a ride on a hot day when the tire....

The tire on a bicycle is filled with air to a gauge pressure of 647 kPa at 20◦C. What is the gauge pressure in the tire after a ride on a hot day when the tire air tempera- ture is 69◦C? (Assume constant volume and a constant atmospheric pressure of 101.3 kPa.)
Answer in units of kPa.

Sol:
Here the formulae used is:

P1V1=n1RT1
P2V2=n2RT2

Where P1=po+pg
P1=101.3kPa + 647kPa= 748.3kPa
n1=n2
also given that V1=V2.
Hence, P1/T1=nR/V=P2/T2
P1/P2=T1/T2
or
P2=(P1*T2)/T1 = (748.3 *(273+69))/(273+20)
P2=748.3kPa(342K/293K)= 748.3kPa * (1.167)=873.44kPa

SQL Homework Help: Could you write the SQL commands that would implement this profile...

#User profiles
Your company has hired several new people for a new department project in your regions. This department will have some different requirements from regular works, and the DBA wants to ensure that the new hires will not be getting stepped on by current users in the database and vise versa. To help insulate the new hires, it has been decided to create a specific profile for them. The profile name will be NEWREG1 and it will need to have the following properties:

* After three login attempts, the account should be locked.
* The password should expire after 30 days.
* The same password should not be reused again for at 31 days.
* The account should have a grace period of five days to change an expired password.
* Each user can have 3 concurrent sessions open.

Could you write the SQL commands that would implement this profile. Next, write the query that would list the profile, the profile resource name, and the limit value for the new profile.

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Assignment Help: Derive an expression for link utilization...

Q) Derive an expression for link utilization U of a data link that uses the sliding-window flow control and returns an ACK for every OTHER frame received. Assume error free transmission. Link length is d, propagation velocity is v, frame size is L, and window size is W.

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HomeWork Help: Count back from the secondary after the last frame? Assume error-free operation..

Q) Assume that the primary HDLC station in NRM has sent six I-frames to a secondary. The primary’s N(S) count was three(011 binary) prior to sending the six frames. If the poll bits are in the sixth frame, what will be the N(R) count back from the secondary after the last frame? Assume error-free operation.

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HomeWork Help: What is the current in the bulb..

Q) A 100 W lightbulb is plugged into a standard 120 V outlet. (a) How much does it
cost per 31-day month to leave the light turned continuously? Assume electrical
energy costs US$0.06/kWh. (b) What is the resistance of the bulb? (c) What is the current in the bulb?

Sol:

First let us find the energy used in 31 days is(in kWh) and then let go for calculating the cost.

a) U = P * t = 0.100kW * 31days * 24hrs/day

       = 74.4kWh

Cost per 31 day month = 74.4kW h * $0.06/kW h

  = $4.464

b) The resistance of the bulb is given by,

P = V²/R

R = V²/P

  = (120V)²/100W

=144Ω

c) The current in the bulb is given by,

P = VI

I = P/V

     = 100W/120V

 = 0.833 A

Assignment Help: How much thermal energy is produced in..

Q) A 1250 W radiant heater is constructed to operate at 115 V. (a) What is the current in
the heater when the unit is operating? (b) What is the resistance of the heating coil? (c)
How much thermal energy is produced in 1.0 h?

Sol:

a) We can calculate the current ‘I’ from the power and voltage.

P = IV

I = P/V

= 1250/115

=10.87A

b) We can calculate the Resistance ‘R’ from the Voltage and power

P = V²/R

R = V²/P

= (115)²/1250

=10.58ohms

c) Thermal energy ‘U’ produced in 1 hr=3600secs is given by,

U = P * t =1250 *3600 = 4.5 *10⁶J

Assignment Help: Calculate the resistivity of the wire material..

Q) A wire 4.00 m long and 6.00 mm in diameter has a resistance of 15.0Ω. A
potential difference of 23.0 V is applied between the ends. (a) What is the current in
the wire? (b) What is the magnitude of the current density? (c) Calculate the resistivity
of the wire material. (d) Attempt to use a Table in the chapter to identify the material.

Sol:

Given that L=4m, r=d/2=3mm, V=23V, I =? , Current density J=? , Resistivity =?

From ohms law, we have V=IR

a) Current I = V/R

          =23/15=1.53A

b) Current density, J = Conductivity*Electric field,......................................................................................................................................

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Assignment Help: Looking for a write-up on Piezoelectric Materials and Devices?

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Homework Help: How many customers are waiting in line..

1)A club has two services desks; one at each entrance of the store. Customer arrives at each desk at the average of one every 6 minutes.

The service rate is 4 minutes per customer;

 The club is not considering consolidating the two service desks into one location staffed by two clerks who will be working at the same rate.

       a)      What is the probability of waiting in line?

       b)     How many customers are waiting in line?

       c)      how much time a customer spend at a service desk?(waiting +service time)

       d)     Do you think the club should consolidate the service desks?

Sol:

λ = Arrival rate=6mins, μ = Service rate=4*2=8mins

   a) The probability of waiting in line is given by,

 Where L_q = Average number waiting in line, S = Number of service channels=2

 

       = 1.125 customers

 

Therefore,  

= 1.125*((2*8/6)-1) =1.185

  b) The number of customers waiting in line, L_q =  1.125 customers.

 

  c) The time spent,

Where Ls= Average number in system (including any being served) given by,

Ls = 1.125+6/8=1.875

Ws = 1.875/6= 0.3125mins

  d) No, the club should not consolidate the service desks, since there is a very good customer sharing taking place between the two service desks.

2) A cafeteria has a coffee urn from which customers serve themselves; arrival at the urn follow a poisson distribution at the rate 3 per minutes. customer’s takes about 15 second to serve themselves; exponential distribution.

a)      How many customers would you expect to see at the on the average at the coffee urn?

b)     How long would you expect it to take to get a cup of coffee?

c)      What percentage of time is the urn being used?

d)     What is the probability that three or more customers are in the cafeteria?

e)      If the cafeteria installs an automatic vendor that dispenses a cup of coffee at a constant of 15 seconds, how does this change your answer to a) and b)?

Sol:

a) The number of customers will be

    

Where λ = Arrival rate=3/min, μ = Service rate=4/min

Ls = 3 customers

b) Waiting time,

 

Where

L_q = 2.25

Wq = 0.75mins

c) Percentage time= Wq/ Ws where

Ws=1

Percentage= 75%

d)           

Where n=3, Pn= 0.14

e)          Ls= 4 at max

Therefore from the above formulae, L_q=3.25

Wq= 1.08mins

The reason why I used all the above formulae is because, these formulae’s are called wait line formulae’s, which is mainly, used to calculate the wait times. It has got four models, Model 1-4. Hence based on the requirements the corresponding models are used. Note that all the formulae’s belonging to same model has to be used in one problem.

Physics Homework: Determine the voltage across the resistor..

Q) A battery has three cells connected in series, each with an internal resistance of 0.024Ω and an emf of 1.80V . This battery is connected to a 15.0Ω resistor.

Determine the voltage across the resistor.

Sol:

Since three cells are connected in series, Hence total internal resistance will be equal to, r= 3*0.024=0.072Ω

The current flowing through the circuit is given by,

I= (EMF/R) + r, where EMF=1.80V, R=15.0Ω, r= 0.072Ω

Therefore I= (1.80/15) + 0.072

           = 0.192A

The voltage across the resistor R=15.0Ω is given by,

V_R = IR

   = 0.192*15

   =2.880V