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Consider three nodes, A, B and C, that adopt the slotted ALOHA protocol to contend for a channel. Suppose node A has more data than node B, and node B has more data than node C to be transmitted. Denote by pA, pB, pC the retransmission probability of nodes A, B, and C respectively, assuming that pA >= pB and pB >= pC. a. Calculate the average throughput of node A (i.e. probability of successful transmission for a given slot). What is the total efficiency of the protocol with these three nodes? (10 points) b. If pA = 3pB and pB=3pC, is node A’s average throughput nine times as large as that of node C? Why or why not? Justify your answer. If not, how can you choose pA and pC to make that happen? (10 points) c. In general, suppose there are N nodes, among the N nodes, there are x nodes with retransmission probability p, and y nodes with retransmission probability q, and the rest z nodes with retransmission probability r, where N=x+y+z and p+q+r=1. Provide expressions to compute the average throughput of any node with retransmission probability p, q or r, respectively. What is the overall throughput of the N nodes? (4 points)

Problem 1 Derive the complex and trigonometric FS representation of the following periodic signal z(t). x(1) 1 ALA M -3 -2 1 2 3 4 51

 

Given Yn+1 2n + Yn 1 = 0. with constant, determine when the solution will oscillate. y = 0 = 1 None of the available options 1

 

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?????? 32 ?What is the average signal rate if NRZ-I is used with a transfer rate of 20 Kbps KBaud 10 A KBaud 20 B KBaud 40 © None of the above D

A recent paper on Island Biogeography, Whittaker et al. (2017) Island Biogeography: Taking the long view of nature's laboratories. Science 357 eaam8326], revisited many concepts in this sub-field of Biogeography. Provide one explanation for why island species are more vulnerable to extinction compared to mainland species A 600- 500 - 400- Type Number of extinctions 300- Islands Mainland 200- 100- 0 All Birds Plants Invertebrates Taxon

Chlorophyll concentration in the ocean observed from satellite imagery (image below) is a proxy for: Chlorophyll concentration (mg C m2) 64.00 P Reyes 10.00 r Monterey Bay Big Sur Region 1.00 -125 124 -1 0.10 0.01 Select one: O a. Ocean temperature b. Phytoplankton c. Krill d. Dolphins

The active element of a certain laser is made of a glass rod 31.0 cm long and 1.20 cm in diameter. Assume the average coefficient of linear expansion of the glass is equal to 9.00 x 10-6 (°C) 1. The temperature of the rod increases by 60.0°C. (a) What is the increase in its length? cm (b) What is the increase in its diameter? cm (c) What is the increase in its volume? cm3 Need Help? Read it Master it

**)] 9 Q3. (6 Marks) A circular steel diaphragm is used for design of pressure transducer. The natural frequency (f) and the pressure (P) function of deflection (y) of the diaphragm center are given by: II. 10.21 Et? na? V121-v2p 16Et ? -0.488 3R* (1 - v?) 7 Where P = pressure, a = radius of the diaphragm = 76 mm t = thickness of the diaphragm = 2.7 mm E = Young'smodulus = 1.9x1091 Pa, v = Poisson's ratio = 0.26, p = density of the diaphragm = 6x10 Kg/m a. Calculate the natural frequency fof the pressure transducer, and then deduce the range of frequency in which can be used this transducer. b. What would be the maximum operating pressure difference that could be applied if the maximum deflection at the center is restricted to = 0.14. c. What is the effect of larger diaphragm diameter on the maximum pressure and natu frequency? E Q3. (6 marks) For a circular diaphragm of the type and loading shown in figure below, the maximum normal stress occurs in the radial direction at the outer boundary, expressed as follows: P. Greatest linear deflection occurs at the center and is equal to Yu-Go )-v) 3 Pa 16 Er diaphragm type strainage where P-pressure, a-t-radius of the diaphragm, t-thickness of the diaphragm pressure pickup E-Young's modulus, vPoisson's ratio. For a-6,35 mm, E-20.68x10 Pa, and v=0.2, and for a design stress of 6.2x10 Pa, what maximum deflection may be expected if P-3x10° Pa?

[16] Malathion is a pesticide (mol wt. 330Da) as cuboid shape of dimension (0.8 x 1.0 1.2 nm 3). Assuming its monolayer compact packing, what is the maximum adsorbed mass in mg per m2 area? What value of OFn/n will you observe in QCM experiment, if the adsorbed mass follows Sauerbrey equation? If there is solvent adsorbed on the surface along with the pesticide, how will you propose to determine weight of water in the adsorption layer?

Q7 A biased differential protection scheme employed for a 25 MVA 69 kV/13.8 kV transformer is shown in Figure 27. (a) Assess the sensitivity of the relays when the transformer is operating under normal condition Assume the pickup current of the relay is 200 mA (6) Devise and draw the CTs configuration if the relays maloperated. Show that the relay is not maloperated after reconfiguration of CTs arrangement. Assume both CT1 and CT2 have the following ratios. CT2=250:5 A CT1=721.68:5 A UU A 0 woon A B AR un B ww c WIN W ? RC 000 100 I RC mer 1 RC 000 w OC oc SOC Biased Differential Relays Figure Q7