Consider the schema R = (A, B, C, D, E, G) and the set F of functional dependencies: AB → CD
B → D
DE → B
DEG → AB
AC → DE
R is not in BCNF for many reasons, one of which arises from the functional
dependency AB → CD. Explain why AB → CD shows that R is not in BCNF and then
use the BCNF decomposition algorithm starting with AB → CD to generate a BCNF
decomposition of R. Once that is done, determine whether your result is or is not
dependency preserving, and explain your reasoning.

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?