Determine which of the properties listed in Problem 1.27 hold and which do not
hold for each of the following discrete-time systems. Justify your answers. In each
example, y[n] denotes the system output and x[n] is the system input.
(a) y[n] = x[ -n] (b) y[n] = x[n- 2] - 2x[n- 8]
(c) y[n] = nx[n] (d) y[n] = 8v{x[n - I]}
{
x[n], n ~ 1 { x[n], n ~ 1
(e) y[n] = 0, n = 0 (f) y[n] = 0, n = 0
x[n + 1], n ~ -1 x[n], n ~ - 1
(g) y[n] = x[4n + 1

Ahouse has the following electrical appliance usage (1) single 40w lamp used for 4 hours per day (2) single 60w fan used for 12 hours per day (3) single 200w refrigerator that runs 24 hours per day with compressor run 12 hours and off 12 hours find the solar power inverter size in watt with correction factor of 1.25.

Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?

Coiled springs ought to be very strong and stiff. si3n4 is a strong, stiff material. would you select this material for a spring? explain.