Space product assurance - verification and approval of automatic machine wave soldering 航天產品保險.自動機械波焊的檢定和驗收
The content of the investigation concerns basic concepts in mechanics , dc circuit and mechanical waves 內容涉及動力學、直流電路和機械波中的基本概念。
Ultrasonic is a kind of mechanical wave that frequency is upper 20khz . ultrasonic may be generated by many ultrasonic transducers 超聲波是頻率高于20khz的機械波,它可由多種能量轉換器轉變而成。
Ultrasound is a kind of high frequency mechanical wave which can effectively improve mass transfer and heat transfer , change physical - chemistry phase equilibrium , fasten chemistry reaction rate 超聲波是一種高頻機械波,利用超聲振動、超聲空化能有效強化傳質、傳熱,改變物理化學相平衡,加快化學反應速率。
Mechanics course mainly includes the description of movement of objects , the instantaneous effect of strength , spatial build - up effect of strength , temporal build - up effect of strength , nonindividual body mechanics , mechanical wave and sound , relativity , inalterability and covariability and mechanics foundation of the theory of relativity 力學主要內容包括物體運動的描述,力的瞬時效應,力的空間累積效應,力的時間累積效應,連續體力學,機械波和聲,相對性、不變性與協變性和相對論力學基礎等。
The research shows that students misunderstand the relation between force and motion . gravity and action / reaction ; that in dc circuit , students of different age groups have the belief of " consumption of current " , " clashing currents " and " the battery as a constant current generator " ; that in understanding the concepts of electricity students lack th e knowledge of relating the micro with the macro ; and that students have serious difficulties in understanding the propagation of mechanics wave , the speed of wave and superposition , and do not make a distinction between the initial conditions and the medium properties of the system 具體表現在:學生對力和運動的關系、重力和平衡、作用力與反作用力存在一些誤解;對直流電路,不同年齡的學生不同程度地存在電流消耗、碰撞電流、恒定電流源等觀念,而且對電學概念的理解缺乏宏觀與微觀的聯系;學生在機械波的傳播、波速、波的疊加上存在嚴重的困難,對于機械波的傳播學生不能區分初始條件和媒質特性,并錯誤地將動力學某些觀念與機械波進行類比。