一个实用的WIN95启动界面

本文通过用简单的方法修改ＭＳＤＯＳ．ＳＹＳ和重新配置ＡＵＴＯＥＸＥＣ．ＢＡＴ文件。     

用于省内公路干线网规划研究的启发式模型

本文阐述了一种将运量在运输线路上的配置和投资在项目上的分配相结合的启发式方法的模型。文章对这种方法的原理与应用进行了研究探讨。     

规则回转体自动铺丝轨迹规划与丝束增减

为满足自动铺丝轨迹的满铺覆性要求，针对现阶段自动铺丝轨迹规划存在的不足，提出了不同的丝束增减算法。首先讨论纤维铺放方向的确定和中心轨迹数量的计算，设计不同铺放方向轨迹的生成算法。然后以丝束重叠系数为重要参数，对于纤维局部堆积和空缺问题提出单侧纤维裁剪算法和双侧纤维裁剪算法，并对裁剪后的重叠区域和间隙区域进行面积求解，使得纤维丝束均匀覆于芯模表面。最后基于CATIA CAA二次开发平台，将上述算法集成到纤维铺放CAD系统中，通过运动仿真系统验证算法的正确性。利用提出的丝束增减算法，实现了间隙/重叠区的均匀分布，尽量降低了富树脂区等相关缺陷的聚集对性能的不良影响。     

Investigations into sensing characteristics of circular thin-plate electrostatic sensors for gas path monitoring

Circular thin-plate electrostatic sensors are promising in gas path monitoring due to their advantages of non-intrusiveness and easy installation. The spatial sensitivity and filtering effect are two important performance parameters. In this paper, an analytically mathematical model of induced charge on a circular thin-plate electrode is first derived. Then the spatial sensitivity and filtering effect of the circular electrostatic sensor are investigated by numerical calculations. Finally,experimental studies are performed to testify the theoretical results. Both theoretical and experimental results demonstrate that circular thin-plate electrostatic sensors act as a low-pass filter in the spatial frequency domain, and both the spatial filtering effect and the temporal frequency response characteristics depend strongly on the spatial position and velocity of the charged particle. These conclusions can provide guidelines for the optimal design of circular thin-plate electrostatic sensors.     

GEnx和Trent1000发动机流路与承力机匣对比分析

为了更好地了解大涵道比发动机的双转子布局和三转子布局的设计特点,选取了波音787客机的两款备选发动机GEnx和Trent1000作为对象开展对比分析.通过对两款发动机的内涵流路、承力机匣和转子支承3方面的设计特点对比分析,发现通过引入中压转子使得三转子布局的中压和高压转子的叶片机都获得了更有利的转速与结构尺寸;三转子布局在承力机匣和中、低压涡轮轴等结构比双转子发动机的设计更复杂;两种布局都无法解决风扇和低压涡轮最佳工作转速的矛盾.     

多轴加工刀轨最优行距计算方法研究

以五轴加工为例,对多轴加工行距提出了一套刀轨最优行距计算方法。该方法通过推导五轴加工刀具运动刃口回转面包络方程,计算相邻轨迹刀具包络面的交线,即残余凸台的顶尖线,进一步计算该线到加工曲面的距离,从而得到最大残余高度值,由此判断当前行距的优劣,据此进行进一步的搜索,最终得到最优的行距。     

准分子激光矫正屈光不正的原理及其实现

研究了准分子激光治疗屈光不正的原理及其实现方法，介绍了准分子激光治疗屈光不正的原理及其种类。在初始角膜模型假设的基础上，提出了能够用于近视、远视和散光等屈光手术的数学模型，计算出切削量和切削的层数，并给出了相应的算法框图。就准分子激光角膜切削机理和“飞点扫描”等关键技术进行了研究。研究成果直接用于准分子激光眼科治疗机，并给出了准分子激光眼科治疗机的原理框图。实验和临床数据表明。取得了满意的手术效果。     

比例与非比例加载下30CrMnSiA钢多轴高周疲劳失效分析

为了分析比例与非比例加载下,30CrMnSiA钢的多轴高周疲劳的失效规律。通过对30CrMnSiA钢材料开展比例与非比例(δ=90°)加载下的多轴高周疲劳试验,研究了应力幅比和相位差对疲劳寿命、断口特征及裂纹起裂角度的影响。试验结果表明,对于比例与非比例加载,随着应力幅比的增大,多轴疲劳寿命逐渐增加。对疲劳断口分析发现,裂纹萌生于试件表面,断口有明显的疲劳源区、扩展区和瞬断区,不同加载路径下的试件断口形式有明显差异。通过对起裂角度的分析发现,应力幅比大于0.25时表面裂纹有明显的第Ⅰ阶段向第Ⅱ阶段的转变,且第Ⅰ阶段沿着接近最大剪应力幅值平面方向扩展,第Ⅱ阶段沿着接近最大正应力平面方向扩展。此外,对典型试件的疲劳断口及表面扩展路径进行了分析,研究表明多轴疲劳试验试件裂纹的特征比值在0.3~0.5之间,且裂纹沿深度方向扩展至300 μm时占总寿命的85%以上。      

Cutting path-dependent machinability of SiCp/Al composite under multi-step ultra-precision diamond cutting

Particle-tool interactions, which govern the synergetic deformation of SiC particle reinforced Al matrix composites under mechanical machining, strongly depend on the geometry of particle position residing on cutting path. In the present work, we investigate the influence of cutting path on the machinability of a SiCp/Al composite in multi-step ultra-precision diamond cutting by combining finite element simulations with experimental observations and characterization. Be consistent with experimentally characterized microstructures, the simulated SiCp/Al composite is considered to be composed of randomly distributed polygonally-shaped SiC particles with a volume fraction of 25vol%. A multi-step cutting strategy with depths of cut ranging from 2 to 10 μm is adopted to achieve an ultimate depth of cut of 10 μm. Intrinsic material parameters and extrinsic cutting conditions utilized in finite element simulations of SiCp/Al cutting are consistent with those used in corresponding experiments. Simulation results reveal different particle-tool interactions and failure modes of SiC particles, as well as their correlations with machining force evolution, residual stress distribution and machined surface topography. A detailed comparison between numerical simulation results and experimental data of multi-step diamond cutting of SiCp/Al composite reveals a substantial impact of the number of cutting steps on particle-tool interactions and machined surface quality. These findings provide guidelines for achieving high surface finish of SiCp/Al composites by ultra-precision diamond cutting.     

结合跳点引导的无人机随机搜索避撞决策方法

针对无人机在城市空域环境和密集交通流下的避撞决策问题，提出马尔科夫决策过程（MDP）和蒙特卡洛树搜索（MCTS）算法对该问题进行建模求解。蒙特卡洛树搜索算法在求解过程中为保证实时性而使其搜索深度受限，容易陷入局部最优，导致在含有静态障碍的场景中无法实现避撞的同时保证全局航迹最优。因此结合跳点搜索算法在全局规划上的优势，建立离散路径点引导无人机并改进奖励函数来权衡飞行路线，在进行动态避撞的同时实现对静态障碍的全局避撞。经过多个实验场景仿真，其结果表明改进后的算法均能在不同场景中获得更好的性能表现。特别是在凹形限飞区空域仿真模型中，改进后的算法相对于原始的蒙特卡洛树搜索算法，其冲突概率降低了36%并且飞行时间缩短47.8%。