宇航元器件搭载试验研究与实践

元器件搭载是国内外航天器,特别是新技术试验卫星中的一类重要试验项目,也是推动元器件成熟和宇航应用的重要手段。从元器件搭载试验验证体制、天地联合验证方法、试验组织、试验结论发布和应用等方面,对元器件搭载试验提出了总体策略,对搭载试验任务内容和要求进行了分析,总结了元器件搭载试验的实践。研究工作对我国宇航元器件搭载试验相关工作具有较高的参考价值。     

交通枢纽设备备件管理信息系统的设计及实现

备件管理是企业管理的重要方面,提高备件管理水平是提高企业竞争力的有效途径。本文研究了交通枢纽管理信息系统的设计和实现。系统包括备件管理、备件申请、备件比价、备件出库及入库、库存预警等功能,为备件管理工作提供了一个高效率的手段,使工作水平上了一个新台阶。     

The Effectiveness of ``On-Board' Maintenance

``On-board' maintenance for offensive weapons systems and its relationship to the allocation of spare parts is discussed. A method for the selection of ``on-board' spare parts is given and an expression for the increase in subsystem reliability through ``on-board' repairs is derived. The concepts of effective reliability, combat effectiveness, and criticality of spare parts are examined. Curves obtained from a hypothetical but realistic maintenance situation show the given relationships between the criticality and the weight and volume of spare parts. These relationships provide a basis for decision on the allocation of spare parts for improving combat effectiveness through ``on-board' maintenance.     

(s,Q) Spare Parts Provisioning Strategy for Periodically Replaced Systems

A joint preventive maintenance and spare parts provisioning strategy is suggested for a failure prone system. Replacements are carried-out at failure, if spare parts are available, and at spare parts replenishment delivery instants. Spare parts are provisioned according to an (s, Q) control policy. The ordering parameters, and preventive maintenance interval are derived from a mathematical model which aims at maximizing the system's availability under a budget constraint. The model takes into account the system lifetime distribution, the preventive and corrective maintenance costs and durations, as well as the total spare parts inventory management cost. Unlike classical inventory management models, the s-expected total cost is derived using the system lifetime distribution. Because each demand for spare parts is triggered by failure, the probabilities of shortage, and surplus will be evaluated based on the system failure distribution rather than the demand distribution during the lead-time. Numerical results have been obtained for an illustrative example.     

基于几何特征的飞机部位识别跟踪算法

针对复杂天气情况下形状可辨的飞机,提出了一种对飞机部位的识别跟踪算法。该算法利用飞机的几何特征,通过数学形态学的原理,在存有噪声干扰的运动图像中简单快速有效地识别出所需目标的重要部位,自动获取其跟踪模板,通过相关匹配技术实现对飞机重要部位的稳定跟踪。给出了应用该算法的具体步骤,并通过实验证明了该算法的有效性。     

基于最小二乘支持向量机的飞机备件多元分类

飞机后续备件配置直接关系到装备的战备完好率和寿命周期费用，对备件的正确分类是进行备件配置决策的前提。支持向量机是采用结构风险最小化原则代替传统统计学中的基于大样本的经验风险最小化原则的新型机器学习方法，具有出色的学习分类能力和推广能力。研究了新型支持向量机算法-最小二乘支持向量机，设计了基于多元分类的最小二乘支持向量机，在此基础上，建立了飞机备件多元分类模型，并对某机型的备件进行了分类。结果表明，基于最小二乘支持向量机的飞机备件多元分类方法是有效、可行的。     

Static shape and vibration control of flexible payloads with applications to robotic assembly

This paper addresses the simultaneous control of vibration and static shape deformation of arbitrarily shaped thin-walled flexible payloads. During robotic assembly of these thin-walled parts, gravity and inertial forces acting on the parts may induce both static shape deformation and vibrations in the part sufficiently large that accurate and high speed assembly of these parts is hindered. Static deformations, which arise due to deformation of the part caused by its own weight under the influence of gravity, lead to misalignment of mating points of the parts. Unwanted vibrations, arising from inertial forces acting on the thin-walled parts as they are positioned for assembly, must damp out before parts can be mated, further hindering the process. In this work, a smart gripper with actuated contact points to grasp the flexible thin-walled parts is proposed to solve this problem. The smart gripper is capable of both part reshaping and active damping of unwanted vibrations of the part. It is fixed to a robotic manipulator and is comprised of multiple linearly actuated fingers with laser-based noncontact proximity sensors, and associated signal processing and controllers. In this paper, a simultaneous vibration and static shape controller is developed. The proposed controller is a composite modal controller in conjunction with a quasi-static modal filter and a bias Kalman filter, which is synthesized based on the reduced-order dynamic model of the flexible payload. A near industrial practice demonstration of the feasibility of the proposed approach is carried out using a proof-of-concept smart gripper to manipulate an automotive fender. Experimental results indicate that unwanted vibrations are successfully damped out, allowing faster cycle times for an assembly process, and static shape deformations are corrected, allowing accurate positioning of parts for assembly.     

通用报表系统的设计与实现

报表的打印输出是各种应用系统中不可缺少的部分,但是由于这些模块的专用性,我们则不可能把一个应用系统中的这一模块不加修改地移到另一个应用系统中直接使用。针对这一现状,本文主要介绍笔者在IBM—PC/XT(及其兼容机)上开发的一个通用报表软件“TYBB”的设计思想和实现方法。     

含旋转部件的动态目标ISAR成像及微多普勒特征提取

含旋转部件的动态目标ISAR成像中,受旋转部件微多普勒调制影响,导致目标成像质量下降,给目标识别带来巨大困难。抑制或消除旋转部件回波是处理带有旋转部件目标ISAR成像的重要内容。现有的算法在处理旋转部件时采用了单个旋转点的假设,虽然取得了较好的效果,但是对实测数据分离效果不明显。为此,本文基于含旋转部件目标主体和旋转部件回波的特点,采用时频分析的方法,实现目标主体与旋转部件回波的分离。对旋转部件信号作单独分析,能更好地获得旋转部件的微动特征参数。仿真和实测数据的结果表明了该方法的有效性。     

SolidWorks二次开发在机械零件设计中的应用与研究

本文分析了机器零件的结构设计,并以SolidWorks在联轴器的结构设计中的应用为例,介绍SolidWorks软件系统在机器零件设计过程中的具体运用.     

基于复数经验模式分解的非旋转对称空间进动目标回波分离及成像研究

对于非旋转对称的弹道中段目标逆合成孔径雷达成像而言,非旋转对称部件回波分量的存在会严重影响目标主体的成像质量。该文通过建立非旋转对称弹道中段目标的回波模型,分析了导弹主体和导弹非旋转对称部件的回波分量的微多普勒差异,提出了基于复数经验模式分解的非旋转对称部件回波分离方法,利用复数经验模式分解的自适应特性,可以有效地分离和重构主体及非旋转对称部件回波分量。仿真结果表明,利用该文提出的方法可显著提高导弹主体部分的成像质量。     

High Reliability Electronic Parts as Justified System Cost Elements

The planned use of premium electronic parts in a forthcoming system is a logical means for assuring failure-free operation comensurate with the best state-of-the-art. However, an over-all analysis of the value of premium parts must show the net worth of improved system performance to more than offset the added initial parts cost. These costs may be in higher procurement costs, added test and evaluation, or more intangible investments. At the outset, a system-production strategy must establish the best level of investment in such features, based upon a conviction that the ``impact' upon reliability improvement will justify the added initial costs. This paper treats the difficult problem of evaluating the system reliability ``impact' introduced by increased parts reliability. The necessity for an early investment strategy will limit the level of analytical sophistication available for predicting reliability. Thus, it is useful to examine the validity of reliability ``parts population analyses' as first-order justifications for investing in high reliability parts for complex electronic systems.     

No-reference image quality assessment using statistical characterization in the shearlet domain

Image and video quality measurements are crucial for many applications, such as acquisition, compression, transmission, enhancement, and reproduction. Nowadays, no-reference (NR) image quality assessment (IQA) methods have drawn extensive attention because it does not rely on any information of original images. However, most of the conventional NR-IQA methods are designed only for one or a set of predefined specific image distortion types, which are unlikely to generalize for evaluating image/video distorted with other types of distortions. In order to estimate a wide range of image distortions, in this paper, we present an efficient general-purpose NR-IQA algorithm which is based on a new multiscale directional transform (shearlet transform) with a strong ability to localize distributed discontinuities. This is mainly based on distorted natural image that leads to significant variation in the spread discontinuities in all directions. Thus, the statistical property of the distorted image is significantly different from that of natural images in fine scale shearlet coefficients, which are referred to as ‘distorted parts’. However, some ‘natural parts’ are reserved in coarse scale shearlet coefficients. The algorithm relies on utilizing the natural parts to predict the natural behavior of distorted parts. The predicted parts act as ‘reference’ and the difference between the reference and distorted parts is used as an indicator to predict the image quality. In order to achieve this goal, we modify the general sparse autoencoder to serve as a predictor to get the predicted parts from natural parts. By translating the NR-IQA problem into classification problem, the predicted parts and distorted parts are utilized to form features and the differences between them are identified by softmax classifier. The resulting algorithm, which we name SHeArlet based No-reference Image quality Assessment (SHANIA), is tested on several database (LIVE, Multiply Distorted LIVE and TID2008) and shown to be suitable for many common distortions, consistent with subjective assessment and comparable to full-reference IQA methods and state-of-the-art general purpose NR-IQA algorithms.     

涡轮部件及螺柱标准件同轴度测量系统的研制

涡轮增压器与变速箱在精密机械制造行业中应用广泛,涡轮部件及螺柱标准件的尺寸准确度是涡轮增压器和变速箱装配精度的一个重要保证,其中同轴度是涡轮部件及螺柱标准件尺寸准确度的一个关键参数,根据涡轮部件及螺柱标准件的同轴度测量需求,研制了一套涡轮部件及螺柱标准件同轴度的测量系统,并基于LabVIEW开发了测量软件。通过实验对螺柱标准件M12的同轴度进行测量并完成测量不确定度评定。实验结果显示四次测量得到的同轴度误差在6.3~6.5 μm,扩展不确定度达2.6 μm,结论表明:研制的同轴度测量系统适用于涡轮部件及螺柱标准件同轴度的高精度测量。     

多级电子备件存储模型

给出了一种基于装备可用度的电子备件存储模型,他能够在备件数量确定的条件下,通过确定最优的两级储备（基层级、中继级）,使装备的使用可用度最大.最后以某电子备件为例,对模型的实用性和有效性进行了验证.     

A novel multiscale nonlinear thresholding method for ultrasonic speckle suppressing

This paper presents a novel speckle suppression method for medical B-scan ultrasonic images. An original image is first separated into two parts with an adaptive filter. These two parts are then transformed into a multiscale wavelet domain and the wavelet coefficients are processed by a soft thresholding method, which is a variation of Donoho's soft thresholding method. The processed coefficients for each part are then transformed back into the space domain. Finally, the denoised image is obtained as the sum of the two processed parts. A computer-simulated image and an in vitro B-scan image of a pig heart have been used to test the performance of this new method. This technique effectively reduces the speckle noise, while preserving the resolvable details. It performs well in comparison to the multiscale thresholding technique without adaptive preprocessing and two other speckle-suppression methods.     

气流纺机框架结构件激光焊接工艺研究

气流纺机框架结构件是某大型纺机厂自行设计的重要零部件且用量较大,该部件由左右两块350×400mm厚3mm激光切割成型A3板之间有一个斜拉连接件三个垂直连接件焊接而成。该框架结构件上装有高速运转纱筒和其他机件,设计要求框架不但有足够的强度而且有较高的尺寸精度和平面度。作者通过对气流纺机框架结合件结构特点和焊接过程热变形温度场、应力场的分析、与原设计焊接方案的焊接结果比较,对原设计焊接方案进行了更改,采取了榫孔焊接方式、选择最佳焊接顺序、预除氧化层和氩气保护措施,用5000WCO2激光器在3000W功率下进行激光连续热传导焊接.在焊接过程中不需要施加任何外力定位,无预应力的影响,因而焊接变形微小,工艺具有较高的稳定性、可靠性。工艺实验在西门子数控五轴四联动激光焊接机床上进行,程序自动化、工作效率高,产品一致性好。激光焊接后的框架结构件平面最大变形小于0.2mm,与原设计焊接方案的实验结果比较,平整度提高5倍以上,焊缝均匀平整、焊缝熔深0.9-1mm,宽度1.75mm,强度达到设计要求。     

Economics Dictates Reliability

The concept of an adequate system is introduced as the lowest total cost system that will do what is expected of it whenever called upon. The minimization of total cost requires that the system use the lowest failure rate parts currently available, that it make full use of these parts and that it have an availability approaching unity. It is suggested that adequate systems are likely to be obtained only if procured on a Total Annual Cost Basis.     

空中微动旋转目标的二维ISAR成像算法

 针对具有高速旋转部件的空中微动目标ISAR回波,本文提出一种基于低调频率匹配滤波的刚体与高速旋转部件回波分离方法.同时针对高速旋转部件的回波特点,提出基于逆-Radon变换的成像算法估计高速旋转散射点图像.最终同时得到微动目标刚体以及旋转部件的聚焦良好的ISAR图像.仿真和实测数据处理结果证明了所提算法的有效性.     

Arm Poses Modeling for Pedestrians with Motion Prior

Arm pose of human, plays an import role for understanding human behaviours. It can directly carry information of people identity, action style, interaction manner, personal habit etc. However the high dynamics of arm parts, especially the movement of forearms and hands, makes that modeling arm parts with high accuracy is challenging. In order to overcome this problem in a specific application, such as modeling arm pose of pedestrians, this paper adopts multiple priors to decrease the uncertainty of arm parts. Firstly, the human structure information, i.e. the prior of human arm parts size, is adopted to remove the impossible arm configuration. Secondly, the prior of arm parts configuration of a specific action is used to constrain the co-occurrence relations of all arm components. Therefore, a Bayesian approach is presented for modeling arm pose to incorporate the multiple priors and the likelihoods from visual observation. This paper proposes an arm model in which its priors can be represented easily. It also describes the priors estimation from the CMU motion dataset by a kernel density estimation, and maximum a posteriori for modeling the parameters of arm parts. Since there are priors for walking style, this method can be directly used for arm pose modeling of pedestrians without pre-training. It is found perform effectively on a HKU campus testing dataset, and also been evaluated on different human sizes and lighting conditions.