局部路径规划在无人工程机械作业中的应用

为实现无人工程机械在自主作业过程中自主行驶和自主避障的目的,设计一种适用于无人工程机械自主作业的局部路径规划方法。利用环境感知系统采集环境数据,分析处理后得到环境栅格地图,并根据无人工程机械尺寸对障碍物进行膨胀处理,应用D*算法搜索出一条代价最小的无碰撞安全行驶路径。实验结果表明：该方法能根据周围环境实时规划无人工程机械行驶路径,满足复杂地形环境的路径规划要求。     

低空数码航测技术在山地区域制作1:2000数字线划图的试验研究——以贵阳高新区核心扎佐片区为例

低空航测技术以其灵活、高效、精准和成本低的特点,能够快速获取影像并完成地形图的测绘,目前已成为国内空间数据获取的重要手段。基于低空航测技术的特点,以贵阳高新区核心区的扎佐片区为试验点进行测绘,通过利用GNSS测量方法实施基础控制点平面测量和高程拟合;采用光电测距三角高程测量;采用GNSS RTK作业测量控制点的高程;采用低空数码航测结合数字摄影测量网格系统(DPGrid)等全数字化航测生产技术平台完成了地形测量作业。结果表明,对以山地与高低为主的地区进行航测,完成1:2000地形图的测绘任务中可以凸显低空航测技术优势。     

GIS技术在路灯监控系统中的应用研究

当前路灯监控多数采用传统方式,管理方式陈旧,预警结果不够直观,需要人工判读路灯故障线路,降低了工作效率。本文,在已有的监控系统基础上,结合GIS技术、无线网络技术,构建路灯预警模型,设计可视化路灯监控系统,以地图可视化的形式,直观地展现路灯监控系统的预警结果。实践验证表明,此方案具有较好的可行性与实用性,可实现"以图管灯、以图查灯"服务,做到实时预警、预警定位。     

微极性流体对轴承转子的影响

通过变分原理求解微极性流体润滑的Reynolds方程得到轴承转子的油膜力,以有限宽刚性Jeffcott转子为研究对象,给出了适用于微极性液体润滑剂的广义雷诺方程,用数值积分法研究了不同参数变化下有限宽轴承转子系统的非线性动力学行为。借助分岔图、Poincare映射图、时间历程图和谱分析等分析了系统的运动形态。数值分析结果表明,系统存在着拟周期运动,且在不同的参数下微极性效应越明显,即L0越小N越大系统越稳定。     

集成数据选择器实现组合逻辑函数技巧

用集成数据选择器可以实现任意组合逻辑函数,实现的方法有代数法和卡诺图法,当逻辑函数变量数较多时,代数法求解过程繁琐,而卡诺图法求解过程较简单。本文给出了用卡诺图法实现任意组合逻辑函数（含约束项和不含约束项两种情况）的方法,教学实践证明,这方法学生容易接受和理解,有较好的教学效果。     

Hot Deformation Behavior and Processing Map of Spray Formed M3∶ 2 High Speed Steel

Hot deformation behavior of a new type of M3∶ 2 high speed steel with niobium addition made by spray forming was investigated based on compression tests in the temperature range of 950-1 150 ℃ and strain rate of 0. 001-10 s~(-1). A comprehensive constitutive equation was obtained,which could be used to predict the flow stress at different strains. Processing map was developed on the basis of the flow stress data using the principles of dynamic material model. The results showed that the flow curves were in fair agreement with the dynamic recrystallization model. The flow stresses,which were calculated by the comprehensive constitutive equation,agreed well with the test data at low strain rates( ≤1 s~(-1)). The material constant( α),stress exponent( n) and the hot deformation activation energy( Q_(HW)) of the new steel were 0. 006 15 MPa~(-1),4. 81 and 546 kJ·mol~(-1),respectively. Analysis of the processing map with an observation of microstructures revealed that hot working processes of the steel could be carried out safely in the domain( T = 1 050-1 150 ℃,ε = 0. 01- 0. 1 s~(-1))with about 33% peak efficiency of power dissipation( η). Cracks was expected in two domains at either lower temperatures( 1 000 ℃) or low strain rates( 0. 001 s~(-1)) with different cracking mechanisms. Flow localization occurred when the strain rates exceeded 1 s~(-1) at all testing temperatures.     

Development of a critical heat flux mapping method for fin-structured surfaces

In this study, we performed critical heat flux (CHF) experiments using structured surfaces to validate the parameter effects and understand their physical meanings. Experimental results showed that the CHF has a peak value as the fin geometry changes. Fins with height of 0.5 mm produced the largest CHF, 1.7 MW/m², and fins longer than 2 mm reduced the CHF values. To explain the results, a CHF mapping method was developed describing the liquid supply-side and demand-side limits. The liquid demand-side limit is governed by the heat removal capability, mainly the nucleate boiling, calculated using the hot spot model. We consider three liquid supply-side limits restricting the liquid supply to the heating surface: capillary limit and counter-current flow limitations (CCFLs). The capillary limit is determined by balancing the capillary pressure and viscous dissipation in the liquid film on the fin side. The CCFL in the structure is calculated using the Wallis correlation and the CCFL in the free volume limits the liquid downward flow by the vapor jetting from the heating surface. The CHF map for our experimental results successfully describes the CHF trend of the structured surfaces. As a result, we concluded that CHF mapping method is an effective means of explaining CHF in pool boiling.     

基于超像素分割的深度图像修复算法

为了提高Kinect相机获取的深度图质量,提出了一种基于超像素分割的图像修复算法。 首先对深度图和彩色图分别 进行双边滤波和超像素分割;其次,结合深度图像和彩色图像相似性,记录彩色分割块的位 置,并对应于 深度图中;最后,在每个分割块对应深度区域中,根据丢失像素点在分割块中所占比例,划 分为无空洞区 域、小空洞区域、大空洞区域和全空洞区域4类。采用快速行进算法对小空洞区域进行 修复,利用中 值填补算法进行大空洞区域修复,对全空洞区域利用邻域区间对应彩色图像相似性进行填充 。4种类型中 的无空洞区域无需修复。实验结果表明,本文方法与FMM、Shen和Scheming的方法相比, 平均均方根误差(RMSE) 分别降低了2.958、0.822和0.078,修复 的主观质量也有所提高。     

瞬时频率引导的小波变换轮廓术相位解包裹技术

提出了一种新的用于小波变换轮廓术进行相位解 包裹的质量图建立方法。对受物体形貌调制的变形 条纹图,利用小波变换相位解调技术获得变形条纹的包裹相位与瞬时频率;将瞬时频率与条 纹载频的绝对 差值和相邻像素点之间瞬时频率的变化程度两方面建立质量图,质量图值的大小可表示位 相质量的好坏, 质量图的值越小,相位质量越可靠;再设定阈值,将质量图分为质量好坏两部分,不同 部分分别采用 扫描线算法和洪流相位解包裹法进行位相解包裹。本文方法在提高解包裹处理速度的同时, 还可以更为精确 地检测出噪声、阴影或条纹突变等区域,使相位解包裹精度和效率得到了保证。通过理论分 析、仿真分析、 实物静态和动态实验表明,与现有的质量图引导的洪流相位解包裹法 相比,本文方法解包裹速 度更快,适用于动态测量中大量变形条纹图的相位精确快速解包裹。