Engineering, 06.05.2020 00:07 aaronk1120
Create a Relational Schema for the following scenario. Include all primary and foreign keys and list any assumptions you make. A research facility has many chemists who work on one or more projects. Attributes of chemists include a unique employee id, a name, rank and email. Each project has one chemist who is given the title of project leader. A chemist may be the leader of several projects. Attributes of a project include a unique project number, start date and description. Each project is assigned to one or more laboratories but each laboratory can house at most one project at any time. Attributes of a laboratory include a building name, room number, capacity and type. The combination of building name and room number is unique. Chemists can borrow equipment from the stockroom. Each time a piece of equipment is borrowed the check-out date is recorded and when it is returned a return date is recorded. The return date is set to 00-00-0000 until the piece of equipment has been returned. Historical data on the equipment is maintained and a chemist can check out the same piece of equipment on multiple dates. Attributes of equipment include a unique serial number, description and cost.
Answers: 1
Engineering, 04.07.2019 18:10, abdirahmansoloman
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?
Answers: 1
Engineering, 06.07.2019 03:20, leapfroggiez
An air-conditioning system consists of a heating section and an evaporative cooler. air enters the heating section at 10°c and 70 percent relative humidity at a rate of 30m^3/min, and it leaves the evaporative cooler at 20°c and 60 percent relatively humidity. if the air conditioning system operates at a total pressure of 98 kpa, determine (a) the temperature and relative humidity of the air when it leaves the heating section, (b) the rate of heat transfer in the heating section, and (c) the rate of water added to air in the evaporative cooler
Answers: 2
Create a Relational Schema for the following scenario. Include all primary and foreign keys and list...
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