系统维修性分配方法的研究

提出一种按系统复杂度的维修性分配方法,并对用该法将多个同类产品组成的串联分系统的平均修复时间ＭＴＴＲ分配至单个产品的使用条件进行讨论。论证了在分系统中同类产品同时发生故障的概率极小的情况下该分系统的寿命分布规律及其对分配方法的影响,建立了必要的约束条件,并举例进行了误差比较。     

Magnetic fine structures in coronal loops

The formation of magnetic fine structures and associated electric currents is considered in the context of the coronal heating problem. The penetration of field-aligned electric currents into the lower atmosphere is discussed. It is argued that currents strong enough to heat the corona can persist only for short periods of time. The formation of thin current sheets is discussed. It is argued that photospheric magnetic structures (flux tubes) play an important role in the generation of coronal currents.     

Observational Tests of the Picture of Disk Accretion

In this chapter, I present a summary of observational tests of the basic picture of disk accretion. An emphasis is placed on tests relevant to black holes, but many of the fundamental results are drawn from studies of other classes of systems. Evidence is discussed for the basic structures of accretion flows. The cases of systems with and without accretion disks are discussed, as is the evidence that disks actually form. Also discussed are the hot spots where accretion streams impact the disks, and the boundary layers in the inner parts of systems where the accretors are not black holes. The nature of slow, large amplitude variability is discussed. It is shown that some of the key predictions of the classical thermal-viscous ionization instability model for producing outbursts are in excellent agreement with observational results. It is also show that there are systems whose outbursts are extremely difficult to explain without invoking variations in the rate of mass transfer from the donor star into the outer accretion disk, or tidally induced variations in the mass transfer rates. Finally, I briefly discuss recent quasar microlensing measurements which give truly independent constraints on the inner accretion geometry around black holes.     

Design of a Correlator for Real-Time Video Comparisons

The problem of locating a reference image within a larger image using a correlation technique is discussed. Although the particular application discussed is that of locating a reference image obtained from one video sensor or a photograph, within the larger field of view obtained from a second video sensor in real time (i.e., at the TV field rate), the results are general and useful for a number of applications. The tradeoffs necessary to obtain real time correlat are discussed and their effect on correlation accuracy is given.     

多种新编程技术在风洞实验测控系统中的实现

结合烟台某学院风洞实验软件的研制和开发这一实例 ,详细阐述了开放式软件框架 ,虚拟仪器仪表 ,组件结构的软件编程思想 ,信号动态时间历程的显示等多种新技术在风洞实验测控软件和数据处理软件中的应用情况 ,并论述了这些新技术为风洞实验软件的研制和开发带来的诸多优越性。     

High efficiency dynamic radioisotope power systems for spaceexploration-a status report

Background on the space exploration program is discussed, and the currently identified NASA exploration missions are contrasted with the missions that were being planned a year ago. Developments in high-efficiency dynamic radioisotope power systems are discussed: and Brayton and Stirling power conversion cycles are compared for the missions planned for the next decade. Issues related to the use of high-efficiency radioisotope (HER) power systems are identified. It is noted that HER power systems are approximately three times as efficient as current radioisotope thermoelectric generators(RTGs) and are therefore significantly cheaper. Additionally, the world's supply of ²³⁸Pu is extremely limited. Currently discussed missions would cut deeply into this supply if powered by RTGs     

Advanced Development of ESG Strapdown Navigation Systems

The fundamental problem of inertial navigation, double integration of acceleration to obtain position, is defined and discussed. Mechanizations of both space-stable and local-vertical platform systems are exhibited. The synthesis problem for an electrically suspended gyro (ESG) strapdown system is defined and discussed: readout, readout errors due to vehicle motion, synchronization of readout with system computer, alignment, correction and calibration for mass unbalance drift, and digital mechanization. Alignment, calibration, and acceleration measurement are also discussed. Sources of error involved in the electronic gimbaling including those peculiar to strapdown configuration are discussed and compared to mechanically gimbaled systems. Advanced developments required in the component and systems areas are listed, and it is shown that such development will lead to reduced complexity, higher accuracy, and increased reliability and utility for inertial systems.     

异构数据库集成的研究与实现

对异构数据库集成做了详细的研究并提出了具体的实现方法。通过分析比较了目前已有的集成方案,本文提出集成异构数据库可以有四个步骤,分别是用控制表变化法提取有效数据、用XML定义传输数据格式、用JMS传输数据、用全局数据模式集成数据来实现。     

支持复杂产品研发的WBS

讨论了系统工程与项目管理的区别和联系,指出系统工程与项目管理融合是复杂产品研发项目的要求.提出一种与这种要求相适应的WBS(工作结构分解)模型--PDA-WBS模型,讨论了该模型的特点,并提出了适应系统工程特点的:DWBS模板;最后介绍PDA-WBS模型的软件实现.     

模压绝热接头成型过程压力控制研究

论述了模压过程中压力大小、加压方法对固体火箭发动机模压绝热接头成型质量的影响,试验结果表明模压绝热接头较理想的成型压力为2．5～8 MPa。同时合理考虑流胶余量和模具流胶结构,选择恰当的压力,有利于提高成型工艺的可操作性和稳定性。     

低空突防任务下综合飞行/推进系统的建模与仿真

建立了综合飞行／推进系统的数学模型，介绍了飞机全维非线性数学模型和涡轮风扇发动机非线性部件级数学模型的建模及综合方法。对飞机执行地形中随任务时，飞行员调节飞行速度的方法与基于总能量的调节飞行速度的方法进行了比较。结果表明，基于总能量的方法比飞行员直接控制飞行速度能够减小发动机的燃油消耗，降低发动机的磨损，进而可以增加飞机的航程，延长发动机的使用寿命。     

Implementing Aircraft Identification Schemes by Public Key Cryptosystems

The use of public key cryptosystems for identification purposes has already been suggested. The practical aspects of using such systems for aircraft identification are discussed. It is shown that the digital signature property is not mandatory for implementing an identification procedure. It is then shown how public key distribution systems can be used for identification purposes. The technical difficulties in implementing an identification scheme are finally discussed with possible solutions offered.     

Constant-False-Alarm-Rate Processors for Locally Nonstationary Clutter

A technique for designing normalizing processors for locally non-stationary clutter is discussed. The design procedure assumes the logarithm of the clutter power varies as a polynomial with range. When the actual environment matches the design environment, the false-alarm rate is a constant that is independent of the polynomial coefficients. A measure of the relative target detection capability as a function of the number of normalization cells and the degree of the design-environment polynomial is given. The applicability of the processors to non-Rayleigh clutter is discussed.     

口径天线绕射场的研究

介绍口径天线近场绕射计算的卷积积分法 ,该方法可用 FFT实现快速计算 ,故它是比传统的直接积分或球面波展开法更有效的一种计算模式。在此基础上 ,对圆形和矩形口径天线的近场绕射特性进行了研究。由计算结果可见 ,口径天线在观察面上的绕场分布与口径形状、口径尺寸 ( D/λ)和观察面至口径有关。还对减小口径边缘的近场绕射问题进行了分析     

航空发动机燃烧室进行间断喷油的试验研究

 在各种飞行条件下,航空发动机工况的改变是靠供油量的改变来实现的。而供油量的改变则是由于改变了供油压力。当喷嘴面积和流量系数不变的条件下,向燃烧室的喷油量与喷油压差成平方关系。由于飞机的飞行条件变化很大,喷油压力必将发生很大的变化。喷油压力是燃油在燃烧室里雾化的决定因素之一。当喷射压力低时,燃油的雾化质量不好,会导致燃烧效率的下降。     

一种变K_f-Neuber法及疲劳裂纹形成寿命计算

 本文讨论修正Neuber法中疲劳缺口系数K_f可表示为材料性能、理论应力集中系数和局部塑性变形的函数。在此基础上提出了一种变K_f-Neuber法。试验表明此法具有较好的计算精度。     

伽罗瓦联络格的特性

对于任意完备格P,Q,研究Γ(P,Q)是从P到Q所有伽罗瓦联络形成的集合。在逐点序的条件下,Γ(P,Q)是一个完备格。讨论Γ(P,Q)性质中的格理论,特别是Γ(P,Q)和完备格Q在代数模和分配性之间的相互关系。伽罗瓦联络的特性对信息理论研究具有一定的理论意义。     

Design of multi-sensor attitude determination systems

The design of inexpensive multi-sensor attitude determination systems is discussed. The systems discussed fuse information from a triad of solid state rate gyros with an aiding system mechanized using GPS or magnetometers and accelerometers. Euler angle and quaternion-based sensor fusion algorithms are developed. Methods for gain scheduling and estimator pole placement are presented. Using simulation and flight test results, it is shown that quaternion-based algorithms simplify gain scheduling and improve transient response.     

Large-eddy simulation: achievements and challenges

In this paper, the present state of the large-eddy simulation (LES) technique is discussed. Modeling and numerical issues that are under study will be described, and results of state-of-the-art calculations will be presented to highlight the response of the subgrid-scale models to important features of the flow field. Finally, some challenges for research and applications of LES in the near future will be discussed.     

关于跨声速流动问题的多重解

本文讨论了跨声速流小扰动方程Riemann问题的多重解及物理上可实现的解的判别。