面蚀 surface erosion

面蚀 surface erosion


相关考题:

面蚀是土壤侵蚀中最常见的一种形式,根据它发生的地质条件,土地利用现状及其表现的形态差异,又可分为层状面蚀、()、砂砾化面蚀和()。

材料:Spark erosion is caused by a voltage discharge between the main bearing and journal surface. The cause of the potential is the development of a galvanic element between the ship’s hull, sea water, and the propeller shaft/crankshaft.The oil film acts as a dielectric. The puncture voltage in the bearing depends on the thickness of the oil film. With increasing engine ratings, the specific load in the main bearing is increased. his will reduce the oil film thickness, and enable the discharge to take place at a lower voltage level.Since the hydrodynamic oil film thickness varies through a rotation cycle, the discharge will take place at roughly the same instant during each rotation cycle, i.e. when the film thickness is at its minimum. The roughening will accordingly be concentrated in certain areas on the journal surface. In the early stages, the roughened areas can resemble pitting erosion. but later, as the roughness increases, the small craters will scrape off and pick up white metal-hence the silvery white appearance.Therefore, to ensure protection against spark erosion, the potential level must be kept at maximum 80 mV, which is feasible today with a high efficiency earthing device. If an earthing device is installed, its effectiveness must be checked regularly. Spark erosion is only observed in main bearings and main bearing journals.问题:According to the paragraph one, a voltage between the main bearing and journal surface is produced by______.A.propeller rotationB.leakage from M/E electric control unitC.a galvanic elementD.friction between the main bearing and journal surface______engine ratings increase, the hydrodynamic oil film between the main bearing and journal surface is______.A.The lower/thinnerB.The higher/the thickerC.The lower/thickerD.The higher/thinnerWhen will the spark erosion take place on the journal surface during each rotation cycle?A.when the film thickness is at its minimumB.when the film thickness is at its maximumC.when the engine is on its compression strokeD.when the engine is on its exhaust strokeDuring the engine room watch keeping, which equipment must be noted to ensure protection against spark erosion?A.the antifouling plantB.the earthing deviceC.the main engine electric heating coilsD.the shaft generator请帮忙给出每个问题的正确答案和分析,谢谢!

水力侵蚀形式包括( )。A.溅蚀B.面蚀C.沟蚀D.滑坡

涂面水痕损伤又叫涂面蚀痕损伤

齿轮表面抗点蚀能力主要与齿面硬度有关,齿面硬度越高,则抗点蚀能力越高。

侧向侵蚀(lateral erosion)

水力侵蚀形式包括()。A、溅蚀B、面蚀C、沟蚀D、滑坡

侧蚀作用(lateral erosion)

乳牙Ⅱ类洞何种情况下可制备成无台阶形复面洞()A、乳牙接触点较近面时B、乳牙龈缘较近面时C、乳牙龋蚀较近面时D、乳牙龋蚀及龈缘较近面时E、乳牙接触点、龈缘或龋蚀较近面时

磨蚀(erosion)

面蚀分为鳞片面蚀和()。

土壤侵蚀类型 soil erosion type

鳞片状面蚀

沙砾化面蚀

根据面蚀发生的地质条件、土地利用现状的不同及其表现的形态差异,又可以分为层状面蚀、()、()、()

向源侵蚀(up stream erosion)

侵蚀阶地(erosion terrace)

局部侵蚀基准面(local base level of erosion)

面蚀

填空题面蚀是土壤侵蚀中最常见的一种形式,根据它发生的地质条件,土地利用现状及其表现的形态差异,又可分为层状面蚀、()、砂砾化面蚀和()。

填空题面蚀分为鳞片面蚀和()。

名词解释题局部侵蚀基准面(local base level of erosion)

多选题水力侵蚀形式包括()。A溅蚀B面蚀C沟蚀D滑坡

名词解释题侧蚀作用(lateral erosion)

单选题Surface irregularities, such as erosion and pitting on injection pump plungers, will()Aincrease ignition delayBaffect fuel oil meteringCaffect engine performance at low speedDonly disappear due to fuel oil abrasion

名词解释题下蚀作用(bottom erosion)

名词解释题面蚀 surface erosion