基于改进HHT的一体化电液作动器故障诊断

介绍了机载变排量变转速一体化电动静液作动器(EHA-VPVM,Electro-Hydrostatic Actuator with Variable Pump displacement and Variable Motor speed)的系统结构,根据EHA-VPVM早期故障信号非平稳、时变等特点,采用一种新的时频分析方法希尔伯特黄变换(HHT,Hilbert-Huang Transform)进行信号分析.针对HHT方法的模态混叠和虚假本征模态函数问题,提出两点改进:通过集合经验模式分解算法抑制模态混叠的发生;采用相关系数法保留真实本征模态函数.对EHA-VPVM工程样机进行早期故障诊断实验,用Hilbert边际谱和HHT谱分析永磁无刷直流电机两种工作状态下的振动信号.实验结果表明:改进HHT方法较好解决了HHT的模态混叠和虚假本征模态函数问题,能准确提取研究对象的早期故障特征,对EHA-VPVM早期故障具有良好的诊断效果.     

严防通话失误确保航空安全

重点讨论了如何防止空地通话失误，确保飞行安全。分三个问题进行研究：１、因空地通话失误造成的特别重大飞行事故；２、当前中国民航空地通话存在的问题；３、空地通话语言一定要标准化。     

一类组合神经网络在协同空战分析中的应用

为了在恶劣、复杂的协同空战环境里帮助飞行员进行更有效的决策，在其指挥级，提出了一类有／无教师组合神经网络－ＰＢ－ＳＯＦＭ网络，并用它来完成目标分析和攻击排序。对于典型的２：４空战，给出了ＢＰ－ＳＯＦＭ网络的结构，并探讨了各个子网的训练和测试方法，及该组合神经网络的使用方法。设计并实现了一个基于ＢＰ－ＳＯＦＭ网络的多机协同空战仿真系统。仿真结果表明，该系统是可行的。     

修正Rodrigues参数在飞行器定姿中的应用(英文)

There are two attitude estimation algorithms based on the different representations of attitude errors when modified Rodrigues parameters are applied to attitude estimation. The first is multiplicative error attitude estimator （MEAE）, whose attitude error is expressed by the modified Rodrigues parameters representing the rotation from the estimated to the true attitude. The second is subtractive error attitude estimator （SEAE）, whose attitude error is expressed by the arithmetic difference between the true and the estimated attitudes. It is proved that the two algorithms are equivalent in the case of small attitude errors. It is possible to describe rotation without encountering singularity by switching between the modified Rodrigues parameters and their shadow parameters. The attitude parameter switching does not bring disturbance to MEAE, but it does to SEAE. This article introduces a modification to eliminate the disturbance on SEAE, and simulation results demonstrate the efficacy of the presented algorithm.     

解流水车间作业排序问题的一种禁止搜索算法

流水车间的作业排序（Ｆｌｏｗｂｓｈｏｐｓｃｈｅｄｕｌｉｎｇ）问题是生产管理与组合优化领域研究的重要课题。禁止搜索（ＴａｂｕＳｅａｒｃｈ）算法对于这类问题具有较强的寻优能力。本文针对流水车间的作业排序问题设计了一种禁止搜索算法的实现形式，通过大量的算例分析表明，该算法具有良好的寻优性与运算效率。     

板坯连铸结晶器内流场计算方程的研究

本文对计算板坯连铸结晶器内流场时常用的不可压缩粘性流体力学中的动量方程的计算问题进行了讨论，提出新的控制方程，并用示例对计算精度进行了比较。     

A viable microbial community in a subglacial volcanic crater lake, Iceland

We describe a viable microbial community in a subglacial lake within the Grímsv?tn volcanic caldera, Iceland. We used a hot water drill to penetrate the 300-m ice shelf and retrieved lake water and volcanic tephra sediments. We also acquired samples of borehole water before and after penetration to the lake, overlying glacial ice and snow, and water from a nearby subaerial geothermal lake for comparative analyses. Lake water is at the freezing point and fresh (total dissolved solids = 260 mg L(-1)). Detectable numbers of cells were found in samples of the lake water column and tephra sediments: 2 x 10(4) ml(-1) and 4 x 10(7) g(-1), respectively. Plate counts document abundant cold-adapted cultivable organisms in the lake water, but not in the borehole (before penetration) or glacial ice. Denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments amplified from genomic DNA extracted from Grímsv?tn samples indicates that the lake community is distinct from the assemblages of organisms in borehole water (before penetration) and the overlying ice and snow. Sequencing of selected DGGE bands revealed that many sequences are highly similar to known psychrophilic organisms or cloned DNA from other cold environments. Significant uptake of 14C-labeled bicarbonate occurred in dark, low-temperature incubations of lake water samples, indicating the presence of autotrophs. Acetylene reduction assays under similar incubation conditions showed no significant nitrogen fixation potential by lake water samples. This may be a consequence of the inhibition of diazotrophy by nitrogen in the lake.     

钛硅共晶合金中硅化物及其对显微硬度的影响

观察了钛硅共晶系合金的微观组织。综合分析了X射线能谱（X－EDS）、透射电子显微镜（TEM）以及X射线衍射（XRD）结果，确认了铸态组织中析出的硅化物本质，并测得该硅化物的显微维氏硬度。结果表明，钛硅共晶合金铸态组织由α-Ti和Ti5Si3两相组成。亚共晶钛硅合金中共晶区比枝晶区具有更高的显微硬度，而共晶和过共晶合金的共晶区显微硬度明显高于亚共晶合金。     

基于XML的Web制造资源数据交换

本文以MS SQL Server2000作为数据资源的服务平台，对制造资源进行深入、细致的分析，从而创建与制造资源相关的所有数据库，并在ⅡS中配置SQLXML支持，创建ⅡS虚拟目录，通过使用XML、XSL、SQL等语言编辑模板并将该摸板保存在所创建的虚拟目录下，以实现与数据库的映射，然后通过HTTP直接实现与服务器数据库的连接，从而实现利用XML在分布式网络上进行制造资源数据的查询、修改、删除以及更新等操作，以实现进行制造资源的全面管理与资源共享。     

航空发动机试车数据采集与处理系统

本文介绍一个以微型计算机为中心的试车数据采集与处理系统。该系统具有稳态和动态采集与处理的双重功能。系统使用高速采集硬件,用PL/M语言编写采集和处理程序,采集速度达5000次/秒以上。稳态压力采集使用自行研制的计算机控制扫描阀,并运用了实时校准技术。温度信号的线性化处理使用变权自动分段多项式拟合法求出的热电偶回归方程。系统硬件采取了一系列抗干扰措施,程序中安排了软件滤波。为保证试车安全,采取了计算机报警。