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The meat box temperature control circuit, as used in the ship service refrigeration system, is an example of ______.
A.two position control
B.single speed floating control
C.proportional(比例) control
D.reset control
参考答案
更多 “ The meat box temperature control circuit, as used in the ship service refrigeration system, is an example of ______.A.two position controlB.single speed floating controlC.proportional(比例) controlD.reset control ” 相关考题
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For (71) service, we need a virtual-circuit subnet. Let us see how that works. The idea behind virtual circuits is to avoid having to choose a new (72) for every packet sent. Instead, when a connection is established, a route from the (73)machine to the destination machine is chosen as part of the connection setup and stored in tables inside the (74) That route is used for all traffic flowing over the connection, exactly the same way that the telephone system works. When the connection is released, the virtual circuit is also terminated. With connection-oriented service, each packet carries an (75) telling which virtual circuit it belongs to.A．connectionlessB．connection-orientedC．datagramD．telegram
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The expansion valve used in a refrigeration system regulates theA.superheat of the gas leaving the compressorB.back pressure in the evaporatorC.temperature in the refrigerated spaceD.degree of superheat of the gas leaving the evaporator
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第一组An automatic system usually consists of a control system and an information system. A control system is a system which measures the condition of some entity and, with the information, governs the state of a variable; i.e., speed, temperature, pressure, position, etc. The open-loop system is the simplest form. a control system may assume. It is distinguished from the closed-loop system by the lack of an input which measures the state of the controlled variable; such an input is called a feedback. In modern ships the open-loop system has practically disappeared and the closed-loop system which operates with a feed-back is extensively used. An information system serves the parallel function of monitoring system or plant performance. The monitoring function may serve a number of purposes; specifically it may indicate values of controlled variables to guide remote control operations, warn of off-limit conditions and provide record of performance. In many cases a visual and audible alarm may be provided to warn of off-limit conditions on board ship and, associated with this, the important variables will be recorded on demand. The automatic control system can be more sophisticated by incorporating digital-processing equipment, that is, a computer. This computer is usually fed with signals from all sensors. It scans the values of the sensors and generates alarm signals for off-limit conditions, acting as a super-supervisor. Sometimes, it can even make necessary and take the necessary action to optimize performance without human intervention.The closed-loop system differs from the open-loop system byA.the lack of a feedbackB.the presence of a feed backC.the lack of a computerD.the presence of a computer
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The part of the shipboard electrical system used to control the distribution of power to the branch circuits, is the ______.A.bridge control panelB.disconnect linksC.main switchboardD.governor relay box
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The sensing line for the low pressure cutout switch to a refrigeration system is located ______.A.in the chill box(冰箱)B.before the receiverC.on the suction side of the compressorD.on the discharge side of the compressor
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An increase in the heat load to a refrigeration system will cause ______.A.the suction pressure to decreaseB.the suction temperature to increaseC.increased ice formation on the evaporator coilD.excessive short cycling of the compressor
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Excessive circulation of the lubricating oil with the refrigerant in a refrigeration system will cause______.A.carbon deposits on the compressor suction valvesB.the evaporator temperature to increaseC.rapid corrosion of the thermal expansion valveD.no operating problems
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单选题In a direct expansion type multi-box refrigeration system, the compressor is set up to cycle on and off by the（）A
pressurestatB
high pressure cutoutC
solenoid valveD
low pressure cutout switch
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单选题（）on board ship are used to control and distribute the electrical energy generated by generators.A
GovernorsB
AlternatorsC
BlackboardsD
Switchboards
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单选题A re-heater, as used in an air conditioning system, is designed to control the （）A
chilled water temperatureB
dew point temperatureC
primary air temperatureD
dry bulb temperature
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单选题For (1) service, we need a virtual-circuit subnet. Let us see how that works. The idea behind virtual circuits is to avoid having to choose a new (2) for every packet sent. Instead,when a connection is established, a route from the(3) machine to the destination machine is chosen as part of the connection setup and stored in tables inside the (4) . That route is used for all traffic flowing over the connection, exactly the same way that the telephone system works.When the connection is released, the virtual circuit is also terminated. With connection-oriented service, each packet carries an (5) telling which virtual circuit it belongs to.
空白（3）处应选择（）A
sourceB
routeC
destinationD
host
考题
单选题Which of the following statements is correct concerning a typical shipboard multi-coil refrigeration system?（）A
The liquid receiver functions to collect and remove non-condensable gasesB
A thermostatic expansion valve is used to control refrigerated space temperatureC
Refrigerant temperature in an evaporator is directly related to refrigerant pressureD
Dehydrators must be used continuously in a refrigeration system
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单选题An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.A
oil foaming in the compressorB
higher than normal suction and discharge pressures with a higher box temperatureC
higher than normal discharge pressure with a normal box temperatureD
the compressor to run continuously
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单选题Thermostatic steam pressure reducing valves are used in the fuel oil service system to control the（）A
double bottom fuel oil tank temperatureB
heater supply steam flowC
pressure of the fuel supplied to the burnersD
attemperator steam flow in the heater discharge circuit
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单选题（） is used for sensing the temperature of the room in the air condition system.A
An expansion valveB
An evaporatorC
A thermostatD
A condenser
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单选题The refrigerant leaves the evaporator of a refrigeration system as a low pressure （）.A
sub-cooled liquidB
high temperature liquidC
oil saturated liquidD
superheated vapor
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单选题Moisture in a refrigeration system can cause （）.A
freezing the expansion valve closedB
corrosion of system pipingC
improper temperature regulationD
all of the above
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单选题If an air compressor is used to supply compressed air to outlets throughout the engine room and on deck of a vessel, the system is known as the （）.A
combustion control air systemB
supply air systemC
ships service air systemD
low pressure deck air system
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单选题Which of the following methods is normally used to control the temperature of air distributed from individual cooling coils in an air conditioning system using a chilled water circulation system?（）A
A room thermostat activates an electric heater at each individual chilled air outlet when necessaryB
Varying the number of passes the air makes across the coilsC
Varying the temperature of the water through the coilsD
Varying the quantity of water flowing through the coils
考题
单选题An increase in the heat load to a refrigeration system will cause （）.A
the suction pressure to decreaseB
the suction temperature to increaseC
increased ice formation on the evaporator coilD
excessive short cycling of the compressor
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单选题A solenoid valve used in a refrigeration system should be installed （）.A
with the axis of the solenoid horizontal, sensing temperature of the box, and upstream of the thermal expansion valveB
upright, sensing temperature of the box, and upstream of the thermal expansion valveC
upright, sensing temperature of the box, and downstream of the thermal expansion valveD
upright, sensing heat of the tail coil, and upstream of the thermal expansion valve
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单选题Which of the listed statements is correct concerning refrigeration systems?（）A
Dehydrators must be used continuously in a refrigeration systemB
A 25 ton refrigeration system has the same cooling effect as melting 25 tons of ice in 24 hoursC
A thermostatic expansion valve is used to control refrigerated space temperatureD
The liquid receiver functions to collect and remove non- condensable gases
考题
单选题Compensated flow control or constant flow valves are used in hydraulic systems to（）A
compensate for major leaks in the systemB
maintain the original fluid viscosityC
allow for changes in pressure and temperature within the systemD
assure constant fluid temperature
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单选题What is NOT an advantage of the house-fall system when compared to a married-fall system using two of the ship’s booms? （）A
There is a steady spotting area under the dockside blockB
Loading can be accomplished from a narrow apron without endangering the inboard boomC
The system can be used for working the second deck of a warehouseD
There is more accurate control of cargo drafts required to be stowed in the wings
考题
单选题The meat box temperature control circuit, as used in ship service refrigeration system, is an example of （）A
two position controlB
signal speed floating controlC
proportional controlD
reset control
考题
单选题The receiver used in a refrigeration system（）A
stores liquid refrigerantB
collects non-condensable gasesC
allows refrigerant sub-coolingD
prevents compressor surging
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单选题If an air compressor is used to supply air primarily to the combustion control system and other pneumatic controllers, the entire system is known as the （）.A
control air systemB
forced draft air systemC
supply air systemD
ships service air system
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