一种新颖组合变换器拓扑研究与应用

基于电源模块并联和串联的思想，提出了一种新颖双管正激组合变换器拓扑，克服了双管正激变换器副边二极管电压应力过高，输出电压和电流脉动大，只能应用于输出中低压场合的缺点，具有副边二极管电压应力低，可靠性高，原边开关管电流应力低，输出电压和电流脉动小，磁芯元件体积小等优点，本文对该新颖组合变换器进行分析，仿真和实验，表明适合应用于输入中，高电压，输出高压，大电流场合，并成功应用于某型飞机6KVA逆变器前级变换器，各项技术指标均符合设计要求。     

加权电压控制多路输出正激变换器的研究

研究了一种经济实用的多路输出DC／DC变换器的输出电压控制方法－加权电压控制，该方法可有效地改善多路输出变换器输出的稳态稳压精度和动态响应性能，对应用加权电压控制的两路输出正激变换器进行直流稳态分析，得出直流稳态等效电路模型和输出电路压数学表达式，分析了加权因子对输出电压的影响，给出了设计加权因子的原则和设计方法，通过样机实验，验证了该方法能够较好地实现多路输出稳压指标。     

快速可重构信息系统的框架研究(英文)

变化和重构是快速可重构信息系统 (RRIS)的两个核心概念 ,RRIS对变化的适应或演化能力使它优于传统信息系统。本文首先提出 RRIS的体系结构 ,然后以 RRIS框架为重点 ,讨论框架的定义、分类及设计 ,研究框架的构成、构成元素 (业务构件 )的设计及构件如何在构架的组织下协调地安插在 CORBA的软总线上 ,实现类似硬件IC的即插即用。构件在框架上即插即用的灵活机制及热点构件 (反映变化 )的灵活运用 ,提高了框架的可扩展性、可定制性 ,从而提高了 RRIS适应变化的可重构性。     

Numerical simulation of effects of the August 11, 1999 solar eclipse in the outer ionosphere

The results of a numerical simulation of such parameters of the topside ionosphere as concentration N _e and temperature T _e of electrons, and concentration n(H⁺) and fluxes along the magnetic field lines Φ(H⁺) of H⁺ ions at an altitude of ～2000 km for the conditions of the August 11, 1999 solar eclipse are presented. The calculations were performed using the Global Self-consistent Model of the Thermosphere, Ionosphere, and Protonosphere of the Earth (GSM TIP). It is shown that during the eclipse, in addition to a region of decreased values of T _e in the Northern Hemisphere and in the magnetically conjugate region in the Southern Hemisphere, regions of electron heating emerge in both hemispheres. Simultaneously, an extended region of decreased values of N _e comes into existence and moves behind the Moon’s shadow. Regions with decreased (down to ～30%) and enhanced (up to ～50%) concentrations of H⁺ ions are detected in the global distribution of these ions.     

Nitrogen fixation on early Mars and other terrestrial planets: experimental demonstration of abiotic fixation reactions to nitrite and nitrate

Understanding the abiotic fixation of nitrogen is critical to understanding planetary evolution and the potential origin of life on terrestrial planets. Nitrogen, an essential biochemical element, is certainly necessary for life as we know it to arise. The loss of atmospheric nitrogen can result in an incapacity to sustain liquid water and impact planetary habitability and hydrological processes that shape the surface. However, our current understanding of how such fixation may occur is almost entirely theoretical. This work experimentally examines the chemistry, in both gas and aqueous phases, that would occur from the formation of NO and CO by the shock heating of a model carbon dioxide/nitrogen atmosphere such as is currently thought to exist on early terrestrial planets. The results show that two pathways exist for the abiotic fixation of nitrogen from the atmosphere into the crust: one via HNO and another via NO(2). Fixation via HNO, which requires liquid water, could represent fixation on a planet with liquid water (and hence would also be a source of nitrogen for the origin of life). The pathway via NO(2) does not require liquid water and shows that fixation could occur even when liquid water has been lost from a planet's surface (for example, continuing to remove nitrogen through NO(2) reaction with ice, adsorbed water, etc.).     

Autoignition of fuel-oxidizer mixtures in microgravity

The paper examines the limitations of quasi-steady autoignition theory in providing information needed for the characterization of autoignition temperature fields. Time-dependent autoignition theory is then utilized to examine the autoignition behavior of a reactive system where both wall catalysis and gas phase kinetic rates are significant. It is found that a diverse range of space-time temperature-composition-pressure histories is possible, depending on the system's thermo-kinetic characteristics.     

New insights into Titan's organic chemistry in the gas and aerosol phases.

Titan, the largest satellite of Saturn, with a dense atmosphere very rich in organics, and many couplings in the various parts of its "geofluid", is a reference for studying prebiotic chemistry on a planetary scale. New data have been obtained from experiments simulating this organic chemistry (gas and aerosol phases), within the right ranges of temperature and a careful avoiding of any chemical contamination. They show a very good agreement with the observational data, demonstrating for the first time the formation of all the organic species already detected in Titan atmosphere including, at last, C4N2, together with many other species not yet detected in Titan. This strongly suggests the presence of more complex organics in Titan's atmosphere and surface, including high molecular weight polyynes and cyanopolyynes. The NASA-ESA Cassini-Huygens mission has been successfully launched in October 1997. The Cassini spacecraft will reach the Saturn system in 2004 and become an orbiter around Saturn, while the Huygens probe will penetrate into Titan's atmosphere. In situ measurements, in particular from Huygens GC-MS and ACP instruments, will provide a detailed analysis of the organics present in the air, aerosols, and surface. This very ambitious mission should yield much information of crucial importance for our knowledge of the complexity of Titan's chemistry, and, more generally for the field of exobiology.     

基于磨粒分析方法的发动机磨损故障智能诊断技术

磨粒是研究磨损状态时最直接、最重要的信息元，通过对滑油中的磨粒进行监测与分析来判断机械设备的磨损情况，可以预防并监测机械设备的磨损故障。本文运用显微形态学方法建立了一套磨粒显微特征描述体系，以提取磨粒信息并进行磨损故障的模式识别；并结合摩擦学理论和人工智能方法，实现对发动机磨损故障的智能诊断和预测。     

含连续／离散变量结构优化中的神经网络与变尺度模拟退火方法

传统的优化方法难于有效地处理含有连续／离散混合变量优化问题，本文介绍了一种改进的变尺度模拟退火方法并与人工神经网络能量函数模型相结合，用于求解含连续／离散设计变量的工程结构优化问题，较好地解决了模拟退火技术用于工程结构优化时选取具有全局性的初始点困难及迭代次数较多的弱点。算例表明，该方法可以使模拟退火算法从局部最优的陷阱中跳出，最后求出整体最优解。