计算涡轮叶片结构可靠度的自适应重要抽样法

为直接准确地计算系统结构可靠度，提出了自适应重要抽样方法，由极限状态面失效区确定的最初抽样区开始，用与随机变量联合概率密度函数成比例的抽样密度，自适应递增调整抽样，使抽样区稍大于失效区，以减少安全区的追加抽样，提高抽样效率，并将其应用于航空发动机涡轮叶片的结构可靠性分析，在获得相同的准确计算结果时，所需计算量显著减少。     

军用机场净空要求的理论分析

西方对机场净空区范围内不同区域净空要求的影响因素作了深入的分析，初步提出了各区域净空要求确定的原理与方法，为科学地制订机场净空规格提供理论依据。     

一种基于GPS和GIS技术的野外搜寻系统

本文介绍了一种利用ＧＰＳ和ＧＩＳ技术的新型便携式野外搜寻系统。该系统可在搜寻中心和搜寻目标之间建立通讯链路，以便实时传输搜寻目标的定位信息，帮助搜寻人员迅速而准确地完成搜寻任务     

基于分区模型的液氢贮箱地面温度与压力分布研究

针对传统商用软件计算液氢贮箱热分层时的计算量大且耗时长等问题,运用分区模型方法将地面液氢贮箱内部空间分为过热区、饱和区和过冷区3块区域,并离散气相/液相区的质量与能量守恒方程和热力学方程,在确定初始条件便求解液氢贮箱内温度与压力分布。对比分区模型与Fluent计算结果可知,该方法在大幅降低计算资源情况下,可获得液氢贮箱内温度与压力的精确分布,为后续流体混合计算提供初始条件。     

直升机回避区飞行试验技术研究

直升机在一定高度和速度范围内,当无动力或临界发动机失效后,即使旋翼自转或剩余发动机工作,飞行员也来不及操纵和调整直升机飞行状态,直升机会以较大的下降率触地,危及飞行安全.为避免出现上述情况,应确定直升机"回避区"(高度-速度曲线).本文介绍了"回避区"飞行试验技术现状和回避区飞行试验技术的重要性,提出了进行回避区飞行试验的程序和内容.     

扭矩扳子示值超差的调整

扭矩扳子在各企业中应用广泛。其结构并不复杂，但由于其中的弹簧弹力很大，不掌握方法，调整示值时，不但浪费时间，还容易弹出零件伤人。而一般资料中或出厂说明中又很少说明示值超差的调整及装卸方法。为此，我们将在实践中摸索出来的调整方法介绍给大家，以供参考。当示值超差时先不要急于卸开内部。首先将力矩动标尺（即套简5），见附图，调整到手柄一端，以使有限长度的螺丝刀能接触到螺钉2，同时也会使板子中弹簧处于弹力最小状态，然后，用一长杆螺丝刀插入柄后部六方孔中至调整螺钉2，适当调整螺钉2至示值合格。如果调不动或调不好…     

1m外腔He—Ne激光器毛细管调整技巧

在“微小光功率计量标准”中使用的是1m长外腔式He－Ne气体激光器。该激光器毛细管内径只有φ2．1～φ2．4mm，长度为1m，共有4个支撑点，要求1m长4个支撑点直线偏差很小。该激光器在长时间使用中，激光器每次点燃，实际是对激光器加热，关闭时又使激光器冷却，热膨冷缩会破坏毛细管的直度区，或腔体的变化，最终都会使激光器不出激光。由于失调而不出激光是1种常见情况，失调引起不出光可通过调整来恢复。采用同时调整毛细管4个支撑点，该方法的缺点要同时调整8个自由度，这样调整起来就要求有一定的经验，根据衍射图形的变化，作相应调整…     

满足约束的Gn连续过渡曲面的构造

在Erich Hartmann提出的由两基曲面线性组合构造G^n连续过渡曲面方法的基础上，针对该方法存在很难找到合适的参数变换的问题，提出了一种基于基曲面局部区域重新参数化构造G^n连续过渡曲面的方法。通过对基曲面上切触线附近区域部分曲面重新参数化，再由重新参数化局部基曲面线性组合构造G^n连续过渡曲面。这样将两基曲面间构造过渡曲面的问题转化为在重新参数化局部基曲面间构造过渡曲面。以构造G^1连续的翼身融合面为例，讨论了满足约束要求条件时G^2连续过渡面的构造方法。即先对基曲面上过渡切触线附近的局部区域进行重新参数化，后通过优化求解来确定比例因子和偏移量、平衡因子和调配因子，使过渡曲面满足前后边条线约束，最后利用线性组合来构造G^2连续的过渡面。约束过渡曲面的形状可通过改变重新参数化基曲面的大小来调整．     

苏霍伊研制的S-80涡桨飞机

S—80是苏霍伊设计局股份公司与卡波企业联合研制的，主要将替换陈旧老化的地方航线飞机L—410和安－28，以及部分雅克－40、安－24和安－26飞机。估计这一飞机的市场需求量超过800架。S—80飞机安装有2台通用电气公司研制的CT7－9B发动机，单台推力为1500马力S－80螺旋桨和发动机进气道都配有防冰系统，机翼前缘、尾翼、水平安定面和机组人员座舱的侧向玻璃均可自动除冰。驾驶与显示系统可保证在飞机设备工作或机组成员操作错误时发出警告信号。无线电救援通信设备可接收记录下失事飞机的信号，确定其方位，将接收的信号转发给搜寻救援…     

超音速风洞喷管壁面型线设计的特征线法

本采用索尔（sauer)法分析了二维喷管喉道区流场，得到了一条合理的初值线。在由特征线法确定初始膨胀区后，根据质量平衡的概念设计超音速风洞喷管壁面型线。本方法可供超音速风洞喷管壁面型线设计时参考。     

Position sensitive multiwire proportional counters for X-ray astronomy

The state of the art of the existing position sensitive multiwire proportional counters (PSMWPC) will be briefly reviewed. In particular taking into account the contribution these detectors have already made to our knowledge of the X-ray sky and the expected future steps that will only be possible with new detector development.Finally a new design of multiwire proportional counter will be described. The new generation of this kind of PSMWPC detectors, when operated with a modulating mask or a single grid rotation modulation collimator or, in the future, with a combination of these two techniques will provide images of the high-energy sky with an angular resolution of l min of arc.     

Track-While-Scan Algorithm in a Clutter Environment

A track-while scan (TWS) algorithm is developed for targets in a clutter environment. The problem has been studied using only the position measurements [1, 5-8], but the simulation results have not been satisfactory. Modern processing techniques (FFT processor) ) in air traffic control and surveillance radar receivers provide both position and radial velocity. The radial velocity measurement may be conveniently used in the target-track correlation process, which will reduce the association ambiguity in the clutter environment. t. In the clear environment the algorithm using the position and radial velocity measurements has been treated in [3, 4]. A TWS algorithm, using both position and radial velocity measurements for targets in a clutter environment, is presented here. The algorithm obtained is nonlinear and adaptive. In order to evaluate the improvement due to radial velocity measurement a simulation has been performed on a digital computer. The algorithm was run with and without radial velocity measurements to compare its performances. An improvement was noted especially when the target path included an accelerated portion.     

缝式处理机匣轴向位置对压气机特性影响的机理研究

文中对轴向倾斜缝处理机匣轴向位置的改变如何影响轴流压气机性能进行研究。试验与数值结果均表明三个轴向位置的机匣处理均扩宽压气机的稳定工作范围,轴向位置不变时扩稳效果最好,轴向位置后移的最差。同时轴向位置前移或后移使压气机等熵效率损害程度降低。通过详细地分析压气机内部流场表明：机匣处理轴向位置后移使叶顶机匣约1/3的轴向弦长宽度无机匣处理,因此不能抑制叶顶泄漏流的发展,后移处理机匣缝的抽吸能力弱,致使扩稳效果差;与处理机匣轴向位置未变的比较,轴向位置前移或后移能够减少了间隙流及二次流带来的流动损失,并使叶顶加功量上升,使压气机转子等熵效率提高。     

Automated inspection of through hole solder joints utilizing X-rayimaging

Solder joint inspection has traditionally been done by manual inspection. The disadvantage of manual inspection is the large amount of time required and the decrease in efficiency as operator fatigue occurs. This has prompted the development of automated inspection systems to speed up the inspection process and increase efficiency. Automated inspection systems typically use visible light, infrared light or X-rays to illuminate the board. These systems require solder joint position information that is provided either by CAD data or by human entry of the position information. This paper describes a preliminary, automated inspection system that finds the solder joints in an X-ray image and inspects them using an artificial neural network (ANN). The identification of solder joints in the gray-scale image is done using image processing techniques; CAD data or manual registration of the solder joints is not required. The image processing techniques also yield binary maps (i.e., black and white images) showing the locations of ICs and other components, which is useful for other diagnostics     

On near wall measurements of wall bounded flows—The necessity of an accurate determination of the wall position

The present review paper is an account on the experimental determination of the wall position relative to the probe in wall-bounded turbulent flow studies. A thorough review on common measurement techniques as well as correction methods reveals, that there are a number of pitfalls, that—when not accounted for—can lead to wrong conclusions about the wall position and thereby also on the near-wall behaviour of mean and turbulence quantities. Employing the state-of-the-art databases from direct numerical simulations of wall-bounded turbulent flows various indirect methods have been tested and assessed in terms of their robustness and accuracy. It is also demonstrated that accurate measurements reaching the viscous sublayer are necessary in order to ensure a correctly deduced wall position, and dependent quantities as for instance the near-wall scaling of mean (e.g. Reynolds number dependence of the buffer region or the log law constants) and turbulence (e.g. the near-wall peak location of Reynolds stresses) quantities.In experiments using hot-wires near the wall it is well known that heat conduction between the hot-wire and the wall gives errors and mean velocity data from the viscous sublayer can usually not be used to determine the wall position. In this paper we introduce a new method which takes advantage of the similarity of the probability density distributions (pdf) in the near wall region. By using the high velocity data of the pdf, which is shown not to be affected by heat conduction, the heat conduction problem can be circumvented.Extensive appendices are included, describing the history and present knowledge about the scaling of the mean velocity in the near wall and overlap regions in wall bounded turbulent flows.     

引射器轴向位置对PDE的性能影响实验

根据脉冲爆震发动机(PDE)工作特点为其设计了6组不同结构的圆柱型引射器,并针对各种结构引射器,采用力传感器法对不同轴向位置处引射器的增推性能进行了实验研究,实验采用汽油为燃料,空气为氧化剂。实验结果发现,轴向位置对引射器的增推性能有非常明显的影响,当引射器入口正好位于脉冲爆震发动机出口处(0点)或位于下游1/2倍脉冲爆震发动机直径处时,系统会出现一个至少高于35%的推力增益点,但是当引射器入口从该点继续远离发动机出口位置时,推力将会急剧地下降;当引射器从0点逐渐向上游移动时,引射器的推力增益呈先下降后上升再下降的趋势,最高推力增益可达80.5%。     

Optimum Steady State Position, Velocity, and Acceleration Estimation Using Noisy Sampled Position Data

A one-dimensional tracking filter based on the Kalman filtering techniques for tracking of a dynamic target such as an aircraft is discussed. The target is assumed to be moving with constant acceleration and is acted upon by a plant noise which perturbs its constant acceleration motion. The plant noise accounts for maneuvers and/or other random factors. Analytical results for estimating optimum steady state position, velocity, and acceleration of the target are obtained.     

平面扇形可倾瓦推力轴承性能的研究

可倾瓦推力轴承的最佳支承位置决定了该轴承具有最佳的性能。为了准确确定平面扇形可倾瓦推力轴承的最佳支点位置,本文分析了离心力效应,提出了何时考虑离心力效应的判据和出现空穴现象的判据,较系统地给出了处于最佳支点位置的平面扇形可倾瓦推力轴承的性能计算线图。