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
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
相关考题：
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
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
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
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
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
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
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
单选题In a direct expansion type multi-box refrigeration system, the compressor is set up to cycle on and off by the（）ApressurestatBhigh pressure cutoutCsolenoid valveDlow pressure cutout switch
单选题（）on board ship are used to control and distribute the electrical energy generated by generators.AGovernorsBAlternatorsCBlackboardsDSwitchboards
单选题A re-heater, as used in an air conditioning system, is designed to control the （）Achilled water temperatureBdew point temperatureCprimary air temperatureDdry bulb temperature
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（）AsourceBrouteCdestinationDhost
单选题Which of the following statements is correct concerning a typical shipboard multi-coil refrigeration system?（）AThe liquid receiver functions to collect and remove non-condensable gasesBA thermostatic expansion valve is used to control refrigerated space temperatureCRefrigerant temperature in an evaporator is directly related to refrigerant pressureDDehydrators must be used continuously in a refrigeration system
单选题An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.Aoil foaming in the compressorBhigher than normal suction and discharge pressures with a higher box temperatureChigher than normal discharge pressure with a normal box temperatureDthe compressor to run continuously
单选题Thermostatic steam pressure reducing valves are used in the fuel oil service system to control the（）Adouble bottom fuel oil tank temperatureBheater supply steam flowCpressure of the fuel supplied to the burnersDattemperator steam flow in the heater discharge circuit
单选题（） is used for sensing the temperature of the room in the air condition system.AAn expansion valveBAn evaporatorCA thermostatDA condenser
单选题The refrigerant leaves the evaporator of a refrigeration system as a low pressure （）.Asub-cooled liquidBhigh temperature liquidCoil saturated liquidDsuperheated vapor
单选题Moisture in a refrigeration system can cause （）.Afreezing the expansion valve closedBcorrosion of system pipingCimproper temperature regulationDall of the above
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 （）.Acombustion control air systemBsupply air systemCships service air systemDlow pressure deck air system
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?（）AA room thermostat activates an electric heater at each individual chilled air outlet when necessaryBVarying the number of passes the air makes across the coilsCVarying the temperature of the water through the coilsDVarying the quantity of water flowing through the coils
单选题An increase in the heat load to a refrigeration system will cause （）.Athe suction pressure to decreaseBthe suction temperature to increaseCincreased ice formation on the evaporator coilDexcessive short cycling of the compressor
单选题A solenoid valve used in a refrigeration system should be installed （）.Awith the axis of the solenoid horizontal, sensing temperature of the box, and upstream of the thermal expansion valveBupright, sensing temperature of the box, and upstream of the thermal expansion valveCupright, sensing temperature of the box, and downstream of the thermal expansion valveDupright, sensing heat of the tail coil, and upstream of the thermal expansion valve
单选题Which of the listed statements is correct concerning refrigeration systems?（）ADehydrators must be used continuously in a refrigeration systemBA 25 ton refrigeration system has the same cooling effect as melting 25 tons of ice in 24 hoursCA thermostatic expansion valve is used to control refrigerated space temperatureDThe liquid receiver functions to collect and remove non- condensable gases
单选题Compensated flow control or constant flow valves are used in hydraulic systems to（）Acompensate for major leaks in the systemBmaintain the original fluid viscosityCallow for changes in pressure and temperature within the systemDassure constant fluid temperature
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? （）AThere is a steady spotting area under the dockside blockBLoading can be accomplished from a narrow apron without endangering the inboard boomCThe system can be used for working the second deck of a warehouseDThere is more accurate control of cargo drafts required to be stowed in the wings
单选题The meat box temperature control circuit, as used in ship service refrigeration system, is an example of （）Atwo position controlBsignal speed floating controlCproportional controlDreset control
单选题The receiver used in a refrigeration system（）Astores liquid refrigerantBcollects non-condensable gasesCallows refrigerant sub-coolingDprevents compressor surging
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 （）.Acontrol air systemBforced draft air systemCsupply air systemDships service air system