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Mechanical and propulsion systems prognostics: U.S.


Highcycle fatigue (HCF), involving the premature initiation and/or rapid propagation of cracks to failure due to highfrequency cyclic loading, remains a principal cause of failures in gasturbine propulsion systems.


This requires a further development of current diesel and gasoline engines as well as a careful look to alternatives like fuel cell systems or hybrid propulsion systems.


Increasing shortage on energy resources as well as future emission legislation development increase the pressure to develop more efficient, environmentally friendly propulsion systems for vehicles.


An analysis is made of the optimum motion for three possible propulsion systems: limited exit velocity, limited power, and limited thrust.

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 With the advance of nuclear weapons spacebornes, nuclear propulsion systems and nuclear reactors, the problem of radiation environment becomes more and more important during the last 20 years. Since the electronic devices and systems are quite sensitive to nuclear radiation, they must be well designed and hardened in order to operate and survive in space and near the nuclear reactor or the explosion of a nuclear weapon. So the antinuclear radiation electronics have been formed and developed into... With the advance of nuclear weapons spacebornes, nuclear propulsion systems and nuclear reactors, the problem of radiation environment becomes more and more important during the last 20 years. Since the electronic devices and systems are quite sensitive to nuclear radiation, they must be well designed and hardened in order to operate and survive in space and near the nuclear reactor or the explosion of a nuclear weapon. So the antinuclear radiation electronics have been formed and developed into a new branch of electronics. An outline of so called antinuclear radiation electronics would include three major categories: (1) radiation effects (to make radiation tests and to evaluate the survivabilily); (2) damage mechanism (to study the damage mechanism and to determine the failure modes); (3) nuclear hardening (to make the hardening design and fabrication techniques). An overview of the new speciality is presented in this paper.  本文扼要地介绍抗核辐射电子学这门新兴学科的主要内容及涉及的主要技术和理论问题,并概述了目前的发展状况。  A method for calculating electromagnetic and electromechanical transient process in a PWM inverterinduction motor system using the digital computer has been given. A model as a whole is made up by combining a mathematical model of the inverter with the fundamental differertial equations of the induction motor in a suitable form. Original electrical parameters of the induction motor are its equivalent circuit parameters which can be easily acquired. A series of calculations for a typical system(a... A method for calculating electromagnetic and electromechanical transient process in a PWM inverterinduction motor system using the digital computer has been given. A model as a whole is made up by combining a mathematical model of the inverter with the fundamental differertial equations of the induction motor in a suitable form. Original electrical parameters of the induction motor are its equivalent circuit parameters which can be easily acquired. A series of calculations for a typical system(a propulsion system for a deepsubmergence vehical) has shown that the value resulting from calculation is fairly close to the experimental result. A block diagram and a common program for general PWM inverterinduction motor system have been provided. This method is suitable for a nonPWM inverter system.  本文给出一种用数字机计算PWM逆变器异步机系统电磁和机电暂态过程的方法。用所建立的PWM逆变桥数学模型和变换为适当形式的异步机基本微分方程构成系统的整体模型进行计算。计算所用的原始电参数是便于获得的异步机等效电路参数。对一个典型系统——深潜船推进系统所进行的一系列计算表明,计算结果与实际装置的实验结果相当接近。本文建立了适用于各种逆变器异步机系统的计算方框图和通用计算程序。本方法也适用于不调宽逆变器系统的计算。  For the purpose of saving energy, sails used as wind propulsive device for modern ships are reintroduced. Sailassisted motorships, in which engine is the main propulsion system which the sails provide auxiliary propulsion, have been successfully developed abroad. According to statistical information, 15% energy saving can be obtained due to the use of sails, or calculated in another way, an average power gain of 0.30.4 HP can" be resulted from per m2 sail area. In China, research work in this field... For the purpose of saving energy, sails used as wind propulsive device for modern ships are reintroduced. Sailassisted motorships, in which engine is the main propulsion system which the sails provide auxiliary propulsion, have been successfully developed abroad. According to statistical information, 15% energy saving can be obtained due to the use of sails, or calculated in another way, an average power gain of 0.30.4 HP can" be resulted from per m2 sail area. In China, research work in this field has as well begun and results are being applied to actual ships.This present paper deals with the experimental study on aerodynamic performsnce of circulararc sails. Based on test results, influence of sail form and geometrical parameters on aerodynamic performance is discussed. Available data and diagrams given in this paper will facilitate calculation of thrust lateral force, turning moment and help programing for automatic control of sails so as to optimally utilize wind energy.  为了节能的需要,在现代船舶上采用风帆推进装置的方案又被重新提出。在国外,已成功地发展了机主帆副的船舶(或称风帆助航节能船舶)。据统计,由于利用风帆而得到的节能效果约15％左右,每平方米帆面积平均获得的功率约0.3～0.4马力,我国也已开展这方面的研究工作,并准备用之于实船。 本文结合有关任务,对圆弧型风帆的流体动力性能进行了试验研究,探讨风帆的形式及参数等对空气动力性能的影响。文中给出的资料可供设计风帆时计算推力、横向力及编制风帆自动控制程序之用。   << 更多相关文摘 
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