Visual LISP环境下蜗杆传动CAD系统的开发

在AutoCAD 2004的二次开发环境Visual LISP中实现了普通蜗杆传动CAD系统的二次开，包括交互式用户界面，SLD文件实现的传动设计参数曲线图及数据表，Visual LISP驱动程序。可实现传动系统的初步设计计算，齿面接触强度和齿根弯曲强度的校核，蜗轮蜗杆结构尺寸数据报表的生成。该CAD系统界面直观友好，用户操作符合工程设计习惯，提高了蜗杆传动设计的准确性和效率。     

圆柱齿轮传动参数化设计系统的开发

在AutoCAD的二次开发环境Visual LISP中,研究并开发了外啮合圆柱齿轮传动设计系统。系统以最新版《机械设计手册》为依据,采用DCL定义对话框,创建交互式用户界面,运用Visual LISP程序驱动对话框界面,完成设计数据的动态获取和反馈,从而实现渐开线圆柱齿轮的传动设计,包括：设计计算、强度校核和零件的参数化绘图。系统界面友好、设计流程符合工程设计习惯,能有效提高设计效率,减少重复性工作。     

需求单元链接管理的一种新方法

在研发处理较小需求单元的需求管理工具过程中,研发人员面临着如何管理这些单元之间链接的难题。本文首先说明了若干个需求单元及其链接将会构成一个有向图;然后,为了管理这些链接,在介绍了直接操纵数据库法、关联矩阵法、三元组表法等三种方法的基础上,本文提出并实现了把链接作为需求单元属性的新方法;随后详细分析了这四种方法的优缺点;最后讨论了链接使用的方式。经实验证明,新方法和直接操纵数据库法两者的速度差别在105 以上。     

AutoCAD ARX数据库编程方法

本文介绍了一种在AutoCAD ARX程序中使用外部数据库的方法。由于采用了ODBC技术，该方法可以适用于Visual FoxPro,Access,SQL Server等多种数据库。为开发在AutoCAD环境下工作的数据库管理系统提供了有益的研究成果。     

一种新的链接归并排序算法

将链接技术引入归并排序 ,提出了一种以链接技术和归并算法为基础的新排序算法—链接归并排序算法 (以下简称为“链接归并排序”) ,给出了该排序算法的描述、时间复杂度分析及用C语言编写程序进行算法比较的实验结果 .算法分析和实验结果都表明 :链接归并排序方法和待排序数据分布无关 ,其时间复杂度仅为O(N ) ;而且在处理大规模“汇总”一类排序问题时 ,链接归并排序速度明显优于FlashSort、ProportionSplitSort、2 -路重复的K路归并排序和直接K路归并排序等算法。     

基于VB的矩形花键拉刀设计系统的实现

传统的拉刀设计方法效率低，利用计算机设计程序可以使其实现自动化，快速、准确。介绍了基于Visual Basic6．0环境下矩形花键拉刀设计程序，剖析了其中主要的功能模块。该程序可对拉刀的结构参数进行设计计算，并利用AutoCAD集成的VBA开发工具自动绘制出矩形花键拉刀图纸。结果表明其完全满足工程实践要求。     

纤维丝束可铺放性分析技术

通过对复合材料及其先进制造技术进行分析,结合铺放工艺性,提出基于三角网格的复合材料丝束可铺放性分析技术。在现有丝束基准路径和等距路径规划方法中融入分析机制,并系统分析丝束中心线转弯半径和角度偏差等指标。通过分析结果建立分区机制,将原铺层面进行区域划分,并独立进行丝束几何规划,提高制品质量。结合CATIA二次开发工具CAA在Microsoft Visual Studio 2005平台上实现丝束几何生成与分析功能,并对分析结果与分区结果的正确性进行验证。此研究为复合材料先进制造技术的发展提供了重要思路。     

基于DELMIA的飞机货物可装载性平台设计

现阶段国内航空货运时间周期中95%要用在航空货运站,尤其是收货时对于特殊尺寸的货物能否装入窄体客机货舱的判断耗时较多。为了解决这一问题,在Visual Studio环境下,利用基于V5 Automation的DELMIA软件二次开发技术,建立了数据库,设计了货物可装载性判别应用平台,利用折半查找法实现货物数据与货舱装载...     

应用离屏DC实现窗口无闪烁图像显示技术

基于Microsoft Windows应用程序，当窗口内容不断刷新时总是会产生闪烁现象。特别针对立体图像对窗口显示，要求在屏幕回扫周期内完成窗口图像的切换刷新，必须避免闪烁现象的发生。通过分析Microsoft Windows设备描述表（DC）和WM＿PAINT消息机制，介绍了一种应用离屏DC实现窗口无闪烁图像显示的技术，并给出了基于MFC的实现类。     

涡轮基组合循环发动机燃油系统流动传热耦合仿真软件开发

为避免燃油系统温度压力过高造成燃油系统故障,针对涡轮基组合循环发动机燃油系统流动传热特性进行了联合仿真软件开发研究.根据燃油系统的工作原理、流动传热机理,建立了燃油系统各个元组件的Flowmaster数学模型,采用Visual Basic(VB)语言基于Microsoft Visual Studio(VS)软件平台二次...     

The effect of inlet conditions on the flow and heat transfer in multiple rotating cavity with axial throughflow

This paper discusses experimental results from two different build configurations of a heated multiple rotating cavity test rig.Measurements of heat transfer from the discs and tangential velocities are presented.The test rig is a 70% full scale version of a high pressure compressor stack of an axial gas turbine engine.Of particular interest are the internal cylindrical cavities formed by adjacent discs and the interaction of these with a central axial throughflow of cooling air.Tests were carried out for a range of non-dimensional parameters representative of high pressure compressor internal air system flows(Re up to 5×106 and Rez up to 2×105).Two different builds have been tested.The most significant difference between these two build configurations is the size of the annular gap between the(non-rotating) drive shaft and the bores of the discs.The heat transfer data were obtained from thermocouple measurements of surface temperature and a conduction solution method.The velocity measurements were made using a two component,LDA system.The heat transfer results from the discs show differences between the two builds.This is attributed to the wider annular gap allowing more of the throughflow to penetrate into the cavity.There are also significant differences between the radial distributions of tangential velocity in the two builds of the test rig.For the narrow annular gap,there is an increase of non-dimensional tangential velocity V/Ωr with radial location to solid body rotation V/Ωr=1.For the wider annular gap,the non-dimensional velocities show a decrease with radial location to solid body rotation.      

Research on Auto-detection for Remainder Particles of Aerospace Relay Based on Wavelet Analysis

Aerospace relay is one kind of electronic components which is used widely in national defense system and aerospace system. The existence of remainder particles induces the reliability declining, which has become a severe problem in the development of aerospace relay. Traditional particle impact noise detection (PIND) method for remainder detection is ineffective for small particles, due to its low precision and involvement of subjective factors. An auto-detection method for PIND output signals is proposed in this paper, which is based on direct wavelet de-noising (DWD), cross-correlation analysis (CCA) and homo-filtering (HF), the method enhances the affectiv-ity of PIND test about the small particles. In the end, some practical PIND output signals are analysed, and the validity of this new method is proved.     

Preparation of Highly Dispersed Antimony-doped Tin Oxide Nano-powder via Ion-exchange Hydrolysis of SnCl4 and SbCl3 and Azeotropic Drying

Antimony-doped tin hydroxide colloid precipitates have been synthesized by hydrolysis of SnCl4 and SbCl3 using: (1) an ion-exchange hydrolysis to remove chlorine ions, and (2) isoamyl acetate as an azeotropic solvent to obviate water. The obtained dried powder is of high dispersivity without any need for further grinding. The size and dispersivity of the final particles are investigated with the aid of TG-DTA, BET, XRD and TEM. After having calcined, the antimony-doped tin oxide nanopowder possesses a tetragonal rutile structure with high dispersivity, uniform particles and low hard agglomeration.     

Effects of Mo on the Microstructure and Hydrogen Sorption Properties of Ti-Mo Getters

The effects of Mo on the microstructure evolution, porosity and hydrogen sorption properties of Ti-Mo getters are investigated in this work. The results show that the addition of Mo prolongs the densification process of Ti-Mo getters and results in a significant amount of sintered pores. With the Mo content increasing, the porosity of getters firstly increases reaching the maximum value as it at- tains about 7.5wt.%, and then drops. At the room temperature, the hydrogen sorption property of getters increases progressively with the Mo content increasing, but the tendency is not very clear before its content lies below 2.5wt.%. When the Mo content achieves about 7.5wt.%, the hydrogen sorption property proves to be the best. The discussion is made about the above mentioned phenomena inclusive of hydrogen sorption properties of getters under different activation conditions (from 500-750 ℃).     

超声速燃烧数值模拟中的湍流与化学反应相互作用模型

高精度数值模拟有助于理解超声速湍流燃烧中湍流与化学反应的相互作用,可为发动机燃烧室等工程应用设计提供可靠的预测模型。除直接数值模拟外,目前在湍流燃烧应用中使用的大涡模拟和雷诺平均Navier-Stokes模拟均需要借助模型模化发生在湍流小尺度上的流动与化学反应过程对湍流大尺度运动的影响。现有的湍流与化学反应相互作用模型大致可分为:火焰面类模型和概率密度函数类模型,2类模型在不同的应用中各自具有优势和局限性。此外,现有模型大都基于低马赫数燃烧,而超声速燃烧中通常会伴随快速混合、局部熄火和再着火以及激波等复杂过程,这为发展其中的湍流与化学反应相互作用模型提出了更多的挑战。     

适于低轨卫星IP网络的单核共享树组播算法(英文)

为了解决低轨卫星IP网络中现有典型源组播算法的信道资源浪费问题,本文提出了一套单核共享树组播算法,即核心群合并共享树(CCST)和加权核心群合并共享树(w-CCST)算法。CCST 算法包括动态近似中心(DAC)选核方法和核心群合并组播路径构建方法。DAC方法专为周期、规律运动的低轨卫星网络提出,不需要复杂的星上计算。在核心群合并方法中,以核节点作为初始核心群,通过核心群和剩余组成员的最短路径方法逐步扩展直至整棵组播树构建完成,从而使得组播树的树代价最小,大大提高了网络的带宽利用率和组播传输效率。w-CCST 算法中所提出的加权因子可以调整树代价和端到端传播时延之间的折衷程度,因此,可以通过调整加权因子来适度增大树代价、降低端到端传播时延以支持某些端到端时延要求苛刻的实时组播业务。最后,与低轨卫星 IP 网络中典型算法进行了性能比较,仿真结果说明,CCST 算法的平均树代价比其它算法显著降低,w-CCST 算法的平均端到端传播时延小于 CCST 算法。     

Jet Vectoring Control Using a Novel Synthetic Jet Actuator

A primary air jet vectoring control system with a novel synthetic jet actuator (SJA) is presented and simulated numerically. The results show that, in comparison with an existing traditional synthetic jet actuator, which is able to perform the duty of either “push” or “pull”, one novel synthetic jet actuator can fulfill both “push” and “pull” functions to vector the primary jet by shifting a slide block inside it. Therefore, because the new actuator possesses greater efficiency, it has potentiality to replace the existing one in various appli- cations, such as thrust vectoring and the reduction of thermal signature. Moreover, as the novel actuator can fulfill those functions that the existing one can not, it may well be expected to popularize it into more flow control systems.     

Nonlinear Adaptive Slewing Motion Control of Spacecraft Truss Driven by Synchronous V-gimbaled CMG Precession

The slewing motion control of a truss arm driven by a V-gimbaled control-moment-gyro (CMG) is a nonlinear control problem. The V-gimbaled CMG consists of a pair of gyros that must precess synchronously. The moment of inertia of the system, the angular momentum of the gyros and the external disturbances are not exactly known. With the help of feedback linearization and recursive Lyapunov design method, an adaptive nonlinear controller is designed to deal with the unknown items. Performance of the proposed controller is verified by simulation.     

An SOR Implicit Time-accurate Scheme in Calculating Unsteady Flows

A new time-accurate marching scheme for unsteady flow calculations is proposed in the present work. This method is the combination of classical Successive Over-Relaxation (SOR) iteration method and Jacobian matrix diagonally dominant splitting method of LUSGS. One advantage of this algorithm is the second-order accuracy because of no factorization error. Another advantage is the low computational cost because the Jacobian matrices and fluxes are only calculated once in each physical time step. And, the SOR algorithm has better convergence property than Gauss-Seidel. To investigate its accuracy and convergency, several unsteady flow computa- tional tests are carried out by using the proposed SOR algorithm. Roe’s FDS scheme is used to discritize the inviscid flux terms. Un- steady computational results of SOR are compared with the experiment results and those of Gauss-Seidel. Results reveal that the numerical results agree well with the experimental data and the second-order accuracy can be obtained as the Gauss-Seidel for unsteady flow computations. The impact of SOR factor is investigated for unsteady computations by using different SOR factors in this algorithm to simulate each computational test. Different numbers of inner iterations are needed to converge to the same criterion for different SOR factors and optimal choice of SOR factor can improve the computational efficiency greatly.