微型飞行器结构的发展及关键技术

微型飞行器从概念的出现到现在的研究与发展,已经经历了很多,出现了各式各样的微型飞行器。介绍了当前微型飞行器所涉及的主要结构及其特点,同时对微型飞行器需要突破的技术和方向进行了阐述。     

微扑翼飞行器的尺度律研究与仿生设计

通过分析飞行动物扑翼飞行中的各种物理参量对飞行特性的影响,得出了能为微扑翼飞行器设计所利用的规律。根据几何相似原理,利用基于量纲的尺度分析从本质上揭示了扑翼飞行中各种物理参量之间的相互联系。分析发现,几何尺度对微扑翼飞行器在翼展、翼面积、翼载荷、展弦比和扑翼频率等总体设计参数的影响趋势和对飞行动物相应物理量的影响趋势一致,但在具体量值上有所差异。根据扑翼飞行动物统计分析得到的尺度律设计并制作出了实际可飞的微扑翼飞行器。     

仿生微扑翼飞行器的翅翼设计与优化

提出了微扑翼机构翅翼的共振激励放大驱动机理及其对翅翼的振动模态要求,并依据该机理用有限元方法研究了微扑翼飞行器的仿生翼设计和优化问题。通过对3种仿昆虫翅翼的模态分析,总结出能够满足共振激励要求的翅翼外型和翅脉布局,建立了参数化的自定义仿生翼模型。在此基础上,以翅翼的展弦比和翅脉关键点的坐标为主要参数,使用有限元优化方法,对仿生翅翼的模态优化进行了初步探讨。文中的建模、分析方法和结论对微扑翼飞行器的分析、设计和应用提供了一定的理论依据。     

The influence of kinematics of blades on the flow structure in deep dynamic stall

This study considers the effect of kinematics on the aerodynamic loads and flow structure around moving blades of micro air vehicles (MAVs) in deep dynamic     

房间空调器能效限定中欧标准法规对比研究

以欧盟EEC362和中国国家标准GB12021.3设定的房间空调器能效限定值为主题,以单风道房间空调器和双风道房间空调器为研究对象,展示了这两种房间空调器准入中国和欧洲市场的时间表,并分析了这对于制冷空调行业的政策导向作用。研究表明,制定房间空调器能效限定值和能效等级等相关政策时,不仅要保证获得健康舒适的环境,提升单机设备的能效比,而且要考虑全球变暖指数(GWP)、产品升级速度等因素,使付出的环境成本最低化。     

Influence of thermal insulation and wind velocity on the SMA actuator for morphing applications

This paper presents the modeling and simulation of shape memory alloy (SMA) wire actuators for morphing micro air vehicles (MAVs) when exposed to high-velocity wind during flight. The specific operating conditions include thermal insulation, varying convective heat-transfer coefficients due to wind velocity, aerodynamic loads, and operation from MAV battery. Application-oriented modeling parameters were determined from a flyable morphing MAV. The simulation could dynamically generate the morphing angle as a function of the electrical input pulse duty cycle. The model showed that compared with 10 % duty cycle, a 25 % duty cycle achieves an energy saving of 33 % and an increase in actuation speed of 3.7 times. Further, increasing the duty cycle has a negligible improvement in energy saving, but the actuation rate is increased by 15.8 times. The SIMULINK® model, which was validated through the ground test, would help in the design of SMA actuators and controllers for aerospace vehicles and automobiles.

     

焊接电弧光谱的分布特征

在试验的基础上,给出了焊接电弧光谱的频域及空间分布的测试结果,分析了焊接电弧光谱的结构。通过分析得出了ＴＩＧ焊电弧光谱空间分布的差异性和ＭＩＧ焊电弧光谱空间分布的相似性,着重指出ＭＩＧ焊电弧光谱与熔滴过渡之间存在密切关系。此外,还对焊接电弧光谱特征的应用提出了方向。     

制造加工约束下连续体拓扑优化的数值实现

针对两类常见的制造加工约束即对称性和重复性下的连续体拓扑优化问题,提出了将敏度值在每轮优化前的修正方法,该方法简单且易于编程实现,实现了对称性或重复性约束条件下连续体拓扑优化设计,通过数值算例对不同制造加工约束下的拓扑结果进行了分析对比,结果表明,研究方法具有可行性和有效性。     

Vibration of circular plate with multiple eccentric circular perforations by the Rayleigh-Ritz method

The free vibration of a circular plate with multiple perforations is analyzed by using the Rayleigh-Ritz method. Admissible functions are assumed to be separable functions of radial and tangential coordinates. Trigonometric functions are assumed in the circumferential direction. The radial shape functions are the boundary characteristic orthogonal polynomials generated following the Gram-Schmidt recurrence scheme. The assumed functions are used to estimate the kinetic and the potential energies of the plate depending on the number and the position of the perforations. The eigenvalues, representing the dimensionless natural frequencies, are compared with the results obtained using Bessel functions, where the exact solution is available. Moreover, the eigenvectors, which are the unknown coefficients of the Rayleigh-Ritz method, are used to present the mode shapes of the plate. To validate the analytical results of the plates with multiple perforations, experimental investigations are also performed. Two unique case studies that are not addressed in the existing literature are considered. The results of the Rayleigh-Ritz method are found to be in good agreement with those from the experiments. Although the method presented can be employed in the vibration analysis of plates with different boundary conditions and shapes of the perforations, circular perforations that are free on the edges are studied in this paper. The results are presented in terms of dimensionless frequencies and mode shapes.     

提高液氨泵机械密封使用性能的措施

对液氮泵在使用过程中机械密封的失效现象进行分析研究，参数核算，确定出失效的原因，由此确定出改造措施，在大庆天然气公司的液氮泵上应用，密封性能和使用寿命得到了提高，改善了工作环境，经济效益非常显著。同时也为解决易挥发性介质的密封问题提供了参考。     

工程设计的发展趋势和未来

论述了工程设计的发展趋势。介绍了未来社会环境与需求，现代设计概念与方法学和工程设计管理。     

Mathematical modeling of fluxgate magnetic gradiometers

Issues of designing fluxgate magnetic gradiometers are considered. The areas of application of fluxgate magnetic gradiometers are determined. The structure and layout of a two-component fluxgate magnetic gradiometer are presented. It is assumed that the fluxgates are strictly coaxial in the gradiometer body. Elements of the classical approach to the mathematical modeling of the spatial arrangement of solids are considered. The bases of the gradiometer body and their transformations during spatial displacement of the gradiometer are given. The problems of mathematical modeling of gradiometers are formulated, basic mathematical models of a two-component fluxgate gradiometer are developed, and the mathematical models are analyzed. A computer experiment was performed. Difference signals from the gradiometer fluxgates for the vertical and horizontal position of the gradiometer body are shown graphically as functions of the magnitude and direction of the geomagnetic field strength vector.     

现代航空发动机健康管理技术与应用

介绍当前航空发动机健康管理系统的发展背景以及现状,讨论航空发动机健康管理系统所采用的几种常用的,如流道分析法,滑油以及碎屑分析法、振动分析等方法,并对每种方法都进行了较为详细的讨论。在流道分析法（GPA）中重点介绍了算法实现以及其优缺点,讨论了其局限性。最后,指出了当前航空发动机健康管理系统所应面对的问题和挑战。     

功能梯度硬质合金与金属陶瓷制备技术的研究进展

硬质合金与金属陶瓷的功能梯度化是现代切削加工材料的一个重要发展方向.介绍了制备功能梯度硬质合金与金属陶瓷的若干工艺,阐述了其制备原理,概述了国内外研发与应用现状,提出了目前所需要解决的关键问题.     

The classification of flaws of metal materials synthesized by the selective laser melting method and the capabilities of nondestructive testing methods for their detection

Flaws in metal parts that are typical for the selective laser melting technique are considered. The flaws are divided into four groups by the degree of their danger. The quantitative and qualitative indices of the flaws are given and the causes of their formation are described.     

阻尼减振结构参数特性分析及动态优化

对阻尼减振结构参数的关取特性、阻尼材料的温度－振频效应及结构的断面形式对结构损耗因子的影响进行了分析。提出在变温度、振频状态下，实行参数解耦，把阻尼材料参数拟合成多项式方程，进行参数动态优化的方法。最后对推土机行走系的轮式阻尼减振结构进行了实际应用，进行了结构参数优化和试验，结果表明试验数据与理论分析相吻合。     

基于活动标架法的二自由度机器人操作性能分析

用活动标架法研究了二自由度机器人机构的运动学 ,得出了机器人机构的一些不变量 ,并根据它们定义了机器人的平移体积、旋转体积、可操作性指标和灵活度 ,用这些指标评价机器人的操作性能。并由此得出了机器人产生奇异的条件 ,研究了工作空间曲面和奇异曲面的几何性质 ,计算了它们的法曲率和高斯曲率     

Problems of engineering diagnostics of electron-beam welding

Features of electron-beam welding (EBW), various types of flaws arising in welded joints during EBW, and the factors causing these flaws’ appearance are considered. The effects of beam focusing and the thickness of the welded metals on the shape of a seam are demonstrated. EBW flaws are classified. The difficulties associated with obtaining informative parameters during EBW are analyzed. Radiation and acoustic methods for engineering diagnostics of EBW are considered. New approaches to the construction of systems for diagnostics of EBW are proposed. Experimental results are presented.     

Nonlinear backprojection in reconstruction nondestructive testing methods

Methods of nonlinear backprojection that are suitable for the solution of problems in tomography with small number of views are considered. Their comparison with the classical back-projection methods is performed. Examples of reconstructions are given; the fields in which back-projection methods are successfully applied are enumerated.     

供应链中车辆路径问题的研究进展及前景

车辆路径问题是供应链研究的一项重要内容。本文概述了近年来车辆路径问题的现状;介绍了车辆路径问题主要的几种分类方法;总结了车辆路径问题中几种常见的附加条件。分别介绍了确定车辆路径问题、随机车辆路径问题和模糊车辆路径问题出现的背景及其具体应用场合,讨论并总结了针对这些问题的不同建模方法和算法求解思路,以及这些算法的优点、局限和适用范围。简要介绍了国内该领域的发展现状,并结合供应链应用的需要,指出车辆路径问题的研究发展方向。