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In a proposed design for an electric automobile, the shaft of a four-pole three-phase induction motor is connected directly to the drive axle; in other words, there is no gear train. The outside diameter of the tires is 20 inches. Instead of a transmission, an electronic converter produces variable-frequency three-phase ac from a 48-V battery. Assuming negligible slip, find the range of frequencies needed for speeds ranging from 5 to70mph. The vehicle, including batteries and occupants, has a mass of1000 kg. The power efficiency of the dc-to-ac converter is 85 percent, and the power efficiency of the motor is 89 percent. a. Find the current taken from the battery as a function of time while accelerating from 0 to 40 mph uniformly (i.e., acceleration is constant) in 10 seconds. Neglect wind load and road friction. b. Repeat assuming that the vehicle is accelerated with constant power.
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The configuration shown in Fig. P9.29 depicts a satellite repeater with two antennas, one pointed towards the antenna of ground station 1 and the other towards the antenna of ground station 2. All antennas are parabolic dishes, antennas A1 and A4 are each 4m in diameter, antennas A2 and A3 are each 2m in diameter, and the distance between the satellite and each of the ground station is 40000km. Upon receiving the signal by its antenna A2, the satellite transponder boosts the power gain by 80dB and then retransmits the signal to A4. The system operates at 10GHz with Pt=1kW. Determine the received power Pr. Assume all antennas to be lossless.
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For protection from electrical hazards and arc flash, always use the proper rubber insulating gloves and ensure they are classified by __________:A. The size and shape of the gloveB. The particular kind of rubber material usedC. The level of voltage and protection they provideD. The weather conditions
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he hybridization of the carbon atom labeled x in the molecule below is 10: HH 1 1 II H-N-C-0-0-H HC-H H A) sp B) sp2 C) sp3 D) sp3dE) sp3d2
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The A-36 steel pipe has a 6061-T6 aluminum core. It issubjected to a tensile force of 200 kN. Determine the averagenormal stress in the aluminum and the steel due to thisloading. The pipe has an outer diameter of 78 mm and aninner diameter of 36mm.
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Consider the following code segment, which traverses two integer arrays of equal length. If any element of arr1 is smaller than the corresponding (i.e., at the same index) element of minArray, the code segment should replace the element of minArray with the corresponding element of arr1. After the code segment executes, minArray should hold the smaller of the two elements originally found at the same indices in arr1 and minArray and arr1 should remain unchanged.for (int c = 0; c < arr1.length; c++){if (arr1[c] < minArray[c]){arr1[c] = minArray[c];}else{minArray[c] = arr1[c];}}Which of the following changes will ensure that the code segment always works as intended?Changing the Boolean expression in line 1 to c Removing lines 58Removing lines 58Swapping the positions of line 5 and line 9Swapping the positions of line 5 and line 9Removing lines 710
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you are a network administrator for a large financial institution. there are several account advisors who are constantly on the road with their windows laptop devices. you want to be able to occasionally check on the health of these laptops, including the ability to receive automated alerts for any unusual activity that may indicate some kind of security breach. which of the following remote management technologies would best help you monitor these laptops?
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the surface of a 50-mm-diameter, thin-walled tube is maintained at 100 oc. in one case, air is in cross flow over the tube with a temperature of 25 oc and a velocity of 30 m/s. in another case, air is in fully developed flow through the tube with a temperature of 25 oc and a mean velocity of 30 m/s. compare the heat flux from the tube to the air for the two cases.
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a polymeric cylinder initially experiences a stress with magnitude (absolute value) of 1.1 mpa when compressed. after 50 days the magnitude of the stress is found to have decreased to 0.52 mpa. determine approximately how long, in days, it will take until the magnitude of the stress reaches 1/10 (one-tenth) of its initial value?
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pet is a commonly used polymer for food and beverage containers. for a pet specimen that experiences cyclic loading with a mean stress of 25 mpa, what is the maximum cyclic tensile stress that the part can experience such that it survives at least 1 million cycles?
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Round-Robin algorithm is particularly useful for time-sharing (interactive) systems, because it provides a good: (a) Response Time (b) Waiting Time (c) Turnaround Time (d) CPU utilization
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a constructor is a method that: group of answer choices with the name classname.constructor. never receives any arguments. performs initialization or setup operations. returns an object of the class.
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you are using the vi editor to manage a text file on a linux system. you want to type new text into the file. when you type, you want the existing text that comes after the cursor to be pushed down.
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when an array is passed to a method: group of answer choices the method has direct access to the original array. a reference to the array is passed. it is passed just as an object. all of the above.
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c assign sizepointer with the address of the larger size. if the sizes are the same, then assign sizepointer with nullptr. ex: if the input is 172 81, then the output is: 172 is the larger size
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Consider the attic of a home located in a hot climate. The floor of the attic is characterized by a width of L1= 10 m while the roof makes an angle of theta=30 degrees from the horizontal direction. The home owner wishes to reduce the heat load tot he home by adhering bright aluminum foil (of emissivity 0.07) onto the surfaces of the attic space. Prior to installation of the foil the surfaces are of emissivity 0.85a) consider installation on the bottom of the attic roof only. Determine the ratio of the radiation heat transfer after to before the installation of the foil.b) installation on the top of the attic floorc) installation on both the roof bottom and floor top
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when resource constraints are added to technical constraints the original project network may change as well as the completion date. t/f
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determine the internal normal force at point c , which is located just to the left of the 60- lb concentrated load. express your answer to three significant figures and include the appropriate units.
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Determine the force created in the hydraulic cylinders EF and AD in order to hold the shovel in equilibrium. The shovel load has a mass of 1.25 Mg and a center of gravity at G. All joints are pin connected.
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Determine the slope and deflection at any distance x from the left end of the beam by the method of integration, the maximum slope, and maximum deflection.The correct answers are the boxed text in the image.
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g raid0 and raid1 differ in which ways: question 34 options: raid0 is used for striping only two drives, raid1 stripes three drives. raid0 stripes data across two or more drives, raid1 mirrors data on one drive to another forming pairs of drives with the same data on them. raid1 requires two additional drives to store ecc data which is not used in raid0. raid0 requires at least two drives to stripe data. raid1 requires at least three drives.
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consider the two different heuristics shown in the table above, for the graph used in the previous questions (shown above as well). answer the following true/false statements - just type t for true and f for false. 'h1' is admissible 'h1' is consistent 'h2' is admissible 'h2' is consistent 'h1' is better (dominating) than 'h2'
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f the hubble plots in figures 2-4 represented three universes that are the same size, which hubble plot belongs to the youngest universe? explain your reasoning
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when passing another motorist, always remember the following: a.) if both centerlines are solid, no passing is allowed. b.) if one centerline is broken, passing is allowed, but only on the side with the broken line. c.) if both centerlines are broken, passing is allowed on both sides. d.) all of the above
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