47《认识小数练习题》
数学四年级第七单元认识小数第一课时习题1、读出下面的小数。
2、看图填上适合的分数或小数。
3、把下面各图中涂色的部分用分数和小数表示出来。
福禄克型万用表使用说明
福禄克FLUKE115型数字万用表的使用方法 一、万用表的作用： 二、万用表又称多用表、三用表、复用表，是一种多功能、多量程的测量仪表，一般的数字万用表可以测量交、直流电压、交、直流电流、频率、电阻、电容、二极管、三极管等。 三、使用数安万用表的注意事项： 1、对测量交流电30V以上、直流电60V以上时，应格外小心，防止触电事故。 2、测量时应正确使用接线端、开关档位和量程。 3、测量电阻、通断性、二极管或电容器以前，应切断电路电源，并把所有的高压电容器放电。 4、仪表有手动（Range）和自动(Auto)两种量程：开机时数字万用表自动进入(Auto)自动量程，仪表会根据被测量值的大小，由大到小自动判断，选择合适的量程，但测量时较长；也可以通过按“Range”键，手动选择量程，测量时间短，精度高。 四、数字万用表各按键注解
四、如何使用数字万用表 1、交流电压的测量（AC ～ 0.06—600V ）： 首先将红表笔插进“V Ω ”孔内，黑表笔插进“com ”孔内，再将旋钮打至交流“V～”档，在已知电压大小的情况下，通过“RANGE ”按键选择合适的量程，在未知电压大小情况下可以直接用“Auto ”自动档，保持接触稳定，便可以直接从显示屏上读取交流电压的数值。还可以通过“MIN MAX ”按键，测量出交流电的最小值、最大值、平均值。交流电 MAX MIN 最大值、最小值、平 HOLD 读数锁定 V ～交流电压、频率档 OFF 关机 V--直流电压档 A--直流电流档 负极黑色插孔 测量电流正极红色插孔 线路通断蜂呜档??? 黄色第二功能键 Ω电阻测量档 mv —直流毫伏电压档 背光灯开关 RANGE 测量量程调节 二极管、-‖-电容测量档 V Ω电压、电阻、二极管、电容 A ～交流电流、频率测量档 V ～交流电压、频率
第47期轮机英语
47期轮机英语考试题目 一单项选择题 A1.The___ engine is used for alternators and some times for main propulsion provide a propeller of between 90 to 120 rpm. A.four-stroke B.two-stroke. C.slow speed D.reversible B2.The abbreviation”MIP”stands for____, A.middle indicating pressure B.mean indicated pressure C.mean pitch D.middle indicated power D3.The cetane number of a diesel fuel oil indicates its____. A.viscosity B.acid content C.heating value D.ignition quality C4.In a two-stroke engine the camshaft rotates at___the enging rotational speed. A.half B.twice C.the same speed as D.four times D5.A diesel enging is similar to a gasoline engine except that the former has no ____. A.cross-head B.cylinder C.connecting rod D.spark plug C6.It is easier to replace a dry cylinder liner than a wet one because____. A.of the thin wall thickedss B.honing makes it easier to maintain the desired oil film C.water seals are not required D.it fits more loosely due to a decrease in heat transfer through the composite wall D7.A main bearing consists of two shells which are secured by means of studs and____. A.tie rods B.though bolts C.lead wires D.bearing caps C8.However fast or slow the combustion rate,it is still a____between carbon,hydrogen,sulph and oxygen that releases heat. A.physical deformation B.state exchange C.chemical reaction D.coalescence A9.During the fuel injection period,fuel pressure must exceed cylinder gas pressure to____. A.ensure penetration and distribution of the fuel in the combustion chamber B.ensure the needle valves is flushed clean duringeach injection C.prevent combustion gas blowback into the open needle valve Dprevent reflected pressure waves when the neddle valve close. B10.In a diesel engine lube oil system ,which of the following parts should be lubricated first? A.Camshaft bearings B.Main bearings C.Piston crowns D.Cylinder walls B11.In a diesel engine closed freshwater cooling system,the amount of coolant flowing through the heat exchanger is controlled by the _____, A.suction pressure regulator B.thermostatic bypass valve C.sea water temperature D.water level in the expansion tank
轮机大管轮英语真题48期
中华人民共和国海事局 2009年第5期海船船员适任证书全国统考试题(总第48期) 科目：轮机英语试卷代号：803 适用对象：无限、近洋航区3000KW及以上船舶大管轮 （本试卷卷面总分100分，及格分为70分，考试时间为100分钟） 答题说明：请选择一个最合适的答案，并将该答案按答题卡要求，在其相应位置上用2B铅笔涂黑。第1题至82题，每题1分，第83题至94题，每题1.5分。 一、单项选择题： 1. The reason why more and more of the large merchant vessels are being powered by medium-speed diesel engines is . A. they operate between 150 and 450 rpm B. they are connected to the propeller by gearing C. their smaller size and weight D. they can be connected directly to the propeller without gearing 2. The closing of the exhaust valves used on a modern, large, low-speed, main propulsion diesel engine may be directly provided by . A. large conical springs B. compressed air pressure C. hydraulic pressure D. exhaust gas pressure 3. One of the factors limiting the amount of toad which can be put on a modem marine diesel engine is the . A. governor sensitivity B. exhaust temperature C. fuel injection pressure D. speed of the cam shaft 4. The desirable properties or a marine fuel oil should inc lude . A. high flash point and high viscosity B. low flash point and high viscosity C. low heating value and high sulphur content D. high heating value and low sulphur content 5. As the plunger moves upwards in the barrel, injection will commence once the plunger bas the spill ports and the pressure builds up. A. opened up B. closed off C. lined up D. taken off 6. In an auxiliary diesel engine bypass type lubricating oil system, the main lube oil pump forces . A. all of the oil used by the engine through a filter B. some of the oil used by the engine through a filter C. some of the oil used by the engine through a centrifuge D. all of the oil used by the engine through a centrifuge 7. Because the circulating water is in a closed loop, is installed to cater for expansion and contraction of the water at different conditions of operation. A. an expansion joint B. a drain tank C. a head tank D. a contraction tank 8. The high air velocity leaving the compressor of an exhaust gas turbocharger is converted to pressure in the . A. inlet nozzle ring B. turbine wheel blade C. diffuser passages D. inlet volute 9. is usually driven by the engine camshaft and supplies pilot air to the cylinder air start valve. A. An air receiver B. An operating valve C. An automatic valve D. An air distributor 10. Diesel engines driving alternators operating in parallel must maintain a set frequency regardless of load changes. The governor characteristic used to accomplish this is known as . A. actuation B. sensitivity C. compensation D. promptness 11. By comparing the exhaust gas temperature of each cylinder, the operator can determine if the load is balanced throughout the engine. The device most commonly used is a . A. tachometer B. pyrometer C. dynamometer D. calorimeter 12. When the ship is going to enter into the harbor, ____. A. change from heavy fuel oil to diesel oil for main engine B. pumping out bilge water C. change sea chest from high level one to lower level one D. test emergency generator 13. If the jacket water temperature rises rapidly above normal in a diesel engine, you should first . A. place standby cooler in operation B. reduce engine toad C. check thermostatic valve D. clean sea water strainer 14. Air cocks, usually positioned at the in a circulating system, is used to get rid of the air in the system. A. bending joint B. expansion tank C. weld D. the highest point 15. Which of the following conditions could contribute to the cracking of a diesel engine cylinder head? A. Leaking seal ring B. Insufficient heat transfer from the exhaust valves C. Blocked cooling water passages to the head D. Excessive scavenging air provided to the engine 16. of an engine crankshaft can be detected by measuring deflections of' crank webs for each unit of the engine. A. Misalignment B. Length C. Strength D. Stresses 17. can be a direct cause of faulty operation of diesel engine fuel injection nozzles. A. Excessive fuel nozzle holder cooling B. Sediment in the fuel supply C. Distortion of the fuel spray pattern D. Improper atomization of the fuel 18. When fuel is injected late into a diesel engine cylinder . A. the exhaust will be clear B. fuel consumption will be low C. all the fuel will be burned at top dead center D. fuel consumption will be high 19. A large change in ambient temperature, or using an oil of a viscosity different than the one recommended by the manufacturer in a mechanical hydraulic governor, will result m the need to adjust the . A. pilot valve opening B. compensating needle valve C. compensating spring tension D. accumulator spring tension 20. Which of the following factors tends to increase scale formation on the saltwater side of a heat exchanger used in a diesel engine cooling water system? A. Baffle plates that have been bent during prior removal. B. Leaks m the cooler tube nest. C. Operating the engine while maintaining a high sea water outlet temperature. D. A punctured sea water strainer supplying cooling water to the heat exchanger. 21. If the scavenge fire is of a more major nature, if there is a risk of the fire extending or if the scavenge trunk is adjacent to the crankcase with risk of a hot spot developing it sometimes becomes necessary to the engine. A. stop B. start C. speed up D. slow down 22. In an operating diesel engine, which of the following conditions is an indication of a leaking air starting valve?
万用表使用说明书
2 3 4 1 A mA μA com V 400mA 10A FUSED CA T1000V CA T Ⅱ600V 万用表使用说明书 1、表笔端子功能叙述： 1、适用于1至10安培的交流和直流电电流测量的输入端子。 2、适用于至400毫安的交流和直流电微安或毫 安测量的输入端子。 3、适用于所有测式的公共端子 4、适用于电压、电阻、 通断性、二极管、电容 测量的输入端子。 2、显示屏功能说明：（见下图） 数显区域 ℃% n μF mAV DC AC Mk Ω Hz Atuo Range HOL 已选用通断性 已选用相对 测量模式 已启用数据保持模式 已选中温度 已选中负载物质循环 已选中二极管测式 电容 电流、电压 直流或交流电压、电流 已选中频率 已选中欧母档 m\M\K----十倍数前缀 已选中自动量程 电池电量不足，应立即更换
1、电表有手动及自动量程两个选择。在自动量程模式内，电表会 为检测到的输入选择最佳量程。当电表在自动量程模式时，会显示Auto Range。手动量程操作如下： （一）每按一次Range键，会递增一个量程。当达到最高量程时电表会回到最低量程； （二）要退出手动量程模式，按住Range两秒钟。 2、Hold键的使用：当按下时表示保存当前读数；再按一下表示 回复正常操作。 3、测量交流和直流电压： 若要最大程度减少包含交流和直流电压元件的未知电压产生不正确读数，首先要选择电表上的交流电压功能，特另记下产生正确测量结果所需的交流电量程。然后，手动选择直流电功能，其直流电量程应等于或高于先前记下的交流电量程。
（一）转动旋转开关，选择交流电或直流电； （二）将红色表笔插入写有V字样的端子中，将黑色表笔插入COM 端子中。 （三）将表笔正确接触到想要的电路测试点，测量其电压。 4、测量交流或直流电流 方法同交流或直流电压的测量方法相同。不同的是将红色表笔插入到A、mA或μA端子孔中，以选择你要的量程。转动旋转开关选择交流直流。测量过程中断开待测的电路路径，然后用表笔正确在断口处。 5、测量电阻及通断性 在测量电阻或电路的通断性时，为避免受到电击或造成电表的 损坏，请确保电路的电源已关闭，并将所有电容器放电。 （一）将旋转开关打到欧母档即Ω位置； （二）将红色表笔插到测式电压的红色表笔端子孔中；
三管轮轮机英语大证考试真题41期
中华人民共和国海事局 2006年第3期海船船员适任证书全国统考试题(总第41期) 科目：轮机英语试卷代号：805 适用对象：无限、近洋航区3000KW及以上船舶二/三管轮 （本试卷卷面总分100分，及格分为70分，考试时间为100分钟） 答题说明：请选择一个最合适的答案，并将该答案按答题卡要求，在其相应位置上用2B铅笔涂黑。第1题至74题，每题1分，第75题至78题，每题1.5分,第79题至80题, 每题10分。 一、单项选择题 1. A diesel engine is similar to a gasoline engine except that the former has no ______. A. cross-head B. spark plug C. connecting rod D. cylinder 2. A diesel engine which is rated for normal operation at a crankshaft speed of 800 RPM, is commonly classed as a ______. A. slow-speed diesel B. medium-speed diesel C. high-speed diesel D. constant-speed diesel 3.Which of the diesel engine components listed increases air density and helps to improve engine operating efficiency? A. Impeller B. Compressor C. After-cooler D. Exhaust diffuser 4.For a given size engine, the two-stroke/cycle diesel engine will deliver more power than a four- stroke/cycle diesel engine because ______. A. it has a longer power stroke B. more air gets into the cylinder each stroke C. it develops twice as many power strokes at the same speed D. higher combustion pressure is developed 5.The intake valves in a diesel engine are reseated by ______. A. cam followers B. push rods C. combustion gases D. valve springs 6.According to the way the energy of the exhaust gases is utilized, pressure-charging can be divided into two main systems, namely, the constant-pressure system and ______. A. the pulse-phase system B. the pulse Doppler system C. the pulse system D. the pulse interval system 7.An over-speed safety device is usually fitted to a generator engine for______in the event of over- speed. A. cutting power off the engine B. increasing the fuel pump setting C. braking the crankshaft D. stabilizing the ship speed 8.What preventative maintenance should be done frequently to diesel engine starting air receivers? A. Drain the accumulated moisture. B. Test the relief valves. C. Watch the temperature to prevent fluctuations in pressure. D. Clean the interior to remove oil and foreign matter. 9.Immediately after any diesel engine is started, the engineer should check the ______. A. crankcase pressure B. lube oil pressure C. seawater pressure D. exhaust temperature 10. A controllable pitch propeller on a diesel driven vessel eliminates the need for ______. A. friction clutches B. disconnect clutches C. reversing gears D. reduction gears 11.In motor ship, ______is often used to recover some of the heat carried in the exhaust gases from the main engine. A. an diesel oil heater B. a waste heat boiler C. a fresh water generator D. a donkey boiler 12.An exhaust gas bypass is installed on a waste heat boiler in order to ______. A. bypass exhaust gas at high loads to prevent excessive back pressure B. bypass a portion of the exhaust gas at peak loads for better efficiency C. recycle exhaust gas to the turbocharger D. minimize moisture condensation in the boiler gas passages at low loads 13.Prior to lighting off a cold automatically fired auxiliary boiler, you should ______. A. check and regulate the water level B. close the air cock once fires are lit C. blow down the gage glass D. assure protective steam flow 14.Flame failure in an automatically fired auxiliary boiler can mostly result from a/an ______. A. incorrect electrode setting B. incorrect nozzle position C. clogged fuel nozzle D. broken high tension lead 15.Waterside scale in a fire-tube boiler may cause ______. A. increased heat transfer B. fireside erosion C. high steam demand D. overheated tubes 16.Which of the following will be the advantage of a centrifugal pump as compared with a reciprocating pump? I. Its discharge is continuous; II. It has no internal valves; III. Upon accidental closing of discharge valve, excessive pressure will not build up A. I, II B. II, III C. I, II, III D. II only 17.Why are removable sleeves installed on centrifugal pump shafts? A. They make it easier to replace the pump shaft packing. B. They can be economically replaced as they wear out. C. They can be removed when it is necessary to lighten the weight of the pump. D. They increase the strength of the shaft. 18.If one of the bilge system manifold valves does not properly seat, the ______. A. bilge well connected to that valve, plus the second bilge well being pumped will be completely emptied B. bilge system will lose vacuum and prevent the other bilges from being pumped out C. bilge well aft connected to that valve will siphon(虹吸) its contents to the forward bilge wells D. discharge pressure will be too high. 19.Which of the listed statements is correct concerning the starting of centrifugal pumps? A. They should always be started with the discharge valve closed. B. They should always be started with the discharge valve opened. C. A priming pump is always required to flood the impeller suction. D. They should always be started with the sealing line valves closed. 20.The simplest method to use for determining if a centrifugal pump is operating as designed, is to ______. A. closely observe the pump discharge temperature B. close off the discharge valve, and watch for a rise in pressure C. momentarily close off the suction valve, and watch for a rise in pressure D. use a clamp on ammeter and compare the readings to past records
轮机英语历年真题43期
中华人民共和国海事局 2007年第2期海船船员适任证书全国统考试题(总第43期) 科目：轮机英语试卷代号：805 适用对象：无限、近洋航区3000KW及以上船舶二/三管轮 （本试卷卷面总分100分，及格分为70分，考试时间为100分钟） 答题说明：请选择一个最合适的答案，并将该答案按答题卡要求，在其相应位置上用2B铅笔涂黑。第1题至74题，每题1分，第75题至78题，每题1.5分,第79题至80题, 每题10分。 一、单项选择题 1.______ the engines, the diesel engine is ______ used engine on board. A. Between/more commonly B. Among/the most commonly C. Between/not more commonly D. Among/ not the most commonly 2.The average pressure exerted on a piston during each power stroke is termed ______. A. indicated horsepower B. mean effective pressure C. exhaust back pressure D. compression pressure 3.The cetane number rates fuels for diesel engines according to its ______. A. antiknock characteristics B. ignition qualities C. rates of vaporization D. viscosity 4.The time between injection and ignition of the fuel is known as ______. A. turbulence lag B. after burning ratio C. pre-ignition lag D. ignition delay 5.______ controls the fuel oil temperature in order to provide oil at the correct viscosity for combustion. A. The viscosity regulator B. The temperature controller C. The flow meter D. The pressure switch 6.Constant cooling the various components of diesel engine has a number of functions except for ______. A. good lubrication B. low thermal stress C. good mechanical properties D. acid corrosion 7. A device which functions to bring a diesel engine to a full stop to protect it from damage is known as a/an ______. A. torque limiter B. over-speed trip C. over-speed governor D. load limit governor 8.Engine speeds at which resonance can occur are termed ______. A. maximum speeds B. full speeds C. sea speeds D. critical speeds 9.Prolonged operation of a diesel engine with a closed cooling water system at lower than normal designed operating temperatures can ______. A. increase power output B. decrease lube oil viscosity C. eliminate fuel knock D. cause sulfuric acid formation 10.______ on a ship transmits power from the engine to the propeller. A. The automatic control system B. The speed regularly system C. The transmission system D. The compression air system 11.In a _____ boiler the hot gases from the furnace pass through the tubes while the water is on the outside. A. water-tube B. fire-tube C. exhaust gas D. composite 12.The fuel supply system to an automatic auxiliary boiler, will be automatically shutdown if the boiler ______. A.salinity is abnormally B.high steam demand is too high C.feed-water flow is low D.water level is abnormally low 13.The water in a steaming auxiliary boiler should be tested daily for ______. A. dissolved oxygen B. chlorides C. sludge D. dissolved nitrogen 14.Ignition failure in an automatically controlled auxiliary boiler could be caused by ______. A. carbon deposits on the flame scanner B. high fuel oil temperature C. low fuel oil viscosity D. high steam pressure 15.The concentration of total dissolved solids in the water of an auxiliary boiler can increase as a result of ______. A. seawater contamination B. frequent surface blows C. dissolved oxygen de-aeration D. frequent bottom blows
万用表使用方法图解
万用表 万用表是一种多功能、多量程的测量仪表，电子电工技术中时刻离不开它。一般万用表可测量直流电流、直流电压、交流电流、交流电压、电阻和音频电平等，有的还可以测电容量、电感量及半导体的一些参数(如β)等。若按显示方式简单区分，万用表可分为指针万用表和数字万用表。 数字万用表是一种多用途电子测量仪器，针对需要多功能、高分辨率、高精度和自动化测量的用户而设计的产品。它们在具有准和稳的同时，集高速数据采集、自动化测量、任意传感器等多种功能于一身。
二. 数字万用表的使用方法图--电阻的测量 第一步：首先红表笔插入VΩ孔黑表笔插入COM孔 第二步：把旋转开关旋转到电阻的位置。 第三步：万用表的读数就是该电阻的阻值。 注意：量程的选择和转换。量程选小了显示屏上会显示“1.”此时应换用较之大的量程;反之，量程选大了的话，显示屏上会显示一个接近于“0”的数，此时应换用较之小的量程。
第一步：正确插入表笔，首先红表笔插入VΩ孔黑表笔插入COM孔 第二步：把万用表的旋转开关旋转到直流电压的位置。 第三步：用表笔的另一端和电池的正负极相对应。 第四步：读出显示器上的数据。 注意：把旋钮选到比估计值大的量程档，接着把表笔接电源或电池两端;保持接触稳定，数值可以直接从显示屏上读取。
第一步：红表笔插入VΩ孔，黑表笔插入COM孔。 第二步：量程旋钮打到V~适当位置。 第三步：将红黑表笔按如图方式插入到插座的孔内。 第四步：读出显示屏上显示的数据。 注意：测试市电时一定要把档位打到750V位置，测量档位一定要比要测试量的电压高，如不了解要测量的电压是多少伏，先用大的档位量，如量的值太小，再慢慢往小档位换。