Experimental determination of the propagation of wireless signals on board a cruise ship

The characterization of the wireless channel on board a cruise ship is considered by means of frequency domain measurements of received power and propagation attenuation. This electromagnetic environment is rather new and is characterized by abundance of reflecting and diffracting elements, so that a significant difference with respect to more common residential and office environments was found. The measurement setup is simple and easy to position and operate; the measurement results were validated by comparison with another independent measurement setup. The results indicate that the power losses for corridors are not a power law of distance, due to scattering; even in large environments such as restaurant halls the presence of reflecting and scattering objects and installations largely affects the received power.     

移动机器人全覆盖路径规划算法研究

针对静态未知环境下移动机器人全覆盖路径规划问题,提出了一种改进优先级蚁群算法.该算法首先通过机器人本体上的传感器构建基于动态栅格法的工作环境;综合考虑栅格属性、机器人转向、邻域栅格距离和未覆盖区域面积大小的基础上构造优先级启发规则,然后利用该规则进行路径全覆盖工作.针对机器人工作过程中出现的死锁问题,文章提出采用蚁群算...     

机器人导航路径的动态细化分工花授粉算法规划

为了减少机器人点对点工作路径长度,提出了个体动态细化分工花授粉算法的路径规划方法.以花授粉算法为基础,将花粉按照适应度划分为精英个体、优等个体、差等个体,并对个体进行动态细化分工.精英个体引领进化方向,优等个体使用改进搜索方式进行寻优,差等个体使用柯西变异逃出局部最优,由此提出了个体动态细化分工花授粉算法.使用个体动态...     

运动链拓扑胚图的同构判断

平面并联机构基于胚图的综合方法中,拓扑胚图的同构判断是关键的环节。针对不含二元杆的运动链拓扑胚图,解决它们之间的同构判断问题。运动链的拓扑胚图与拓扑图相比有着独特的个性,由于在支链上没有二元点,所以图的顶点之间的关系主要是顶点之间的相对位置。根据拓扑胚图的特性,从关于图的邻接矩阵的经典理论出发,建立图的任意顶点之间的路径数矩阵,将路径数矩阵的元素按照一定规则排列成路径数组。论证了拓扑胚图同构的条件。在度序列和一阶路径数组相等的前提下,利用二阶路径数组来判断拓扑胚图是否同构。举实例说明判断过程及具体应用。拓扑胚图同构判断问题的解决不仅为基于胚图的型综合奠定了基础,而且对于某些运动链拓扑图的同构判断也具有普遍意义。     

基于改进蚁群算法的移动机器人路径规划研究

为了提高机器人路径规划算法的收敛速度和收敛精度,提出了基于改进遗传算法的机器人路径规划方法。介绍了栅格建模方法,分析了传统蚁群算法原理。提出了蚂蚁相遇策略提高了算法搜索效率,提出了蚂蚁回退策略避免陷入U形陷阱,设置了信息素感应阈值扩大了算法前期的搜索范围,改进了信息素残留方法使蚁群能够记忆最优路径,提出了信息素自适应调整方法,兼顾了算法前期的大范围搜索和后期的快速收敛。经仿真实验验证,相比于传统蚁群算法,改进算法具有更快的收敛速度、更优的规划结果,且改进算法的蚁群轨迹更加集中至最优解附近。     

基于双目视觉的工业机器人运动轨迹准确度检测

针对工业机器人运动轨迹准确度检测困难的问题,提出了一种基于双目视觉理论的检测方法。根据空间解析几何学中点、线和面三者之间的约束关系,建立了基于直线特征匹配的工业机器人运动轨迹位姿视觉检测模型。基于此模型对一种典型六轴工业机器人运动轨迹的位置偏差和姿态偏差进行了测量。测量结果表明采用这种方法的测量系统结构相对简单,能够方便地进行工业机器人动态轨迹准确度的测量。     

Enhancement of the critical heat flux by using heat spreader

Direct immersion cooling has been considered as one of the promising methods to cool high power density chips. A fluorocarbon liquid such as FC-72, which is chemically and electrically compatible with microelectronic components, is known to be a proper coolant for direct immersion cooling. However, boiling in this dielectric fluid is characterized by its small value of the critical heat flux. In this experimental study, we tried to enhance the critical heat flux by increasing the nucleate boiling area in the heat spreader (Conductive Immersion Cooling Module). Heat flux of 2 MW/m² was successfully removed at the heat source temperature below 78°C in FC-72. Some modified boiling curves at high heat flux were obtained from these modules. Also, the concept of conduction path length is very important in enhancing the critical heat flux by increasing the heat spreader surface area where nucleate boiling occurs.     

A Path Interval Generation Algorithm in Sculptured Object Machining

The features of a sculptured object are represented by a set of section curves. A fast algorithm is presented to calculate cutting depths based on the scallop height using these curves. The calculated cutting depth can be used for tool-path generation. This tool-path generation approach is particularly useful for constant z level contouring and high-speed machining.     

基于虚拟现实技术的混凝土泵车智能浇注的研究

对混凝土泵车浇注过程进行了分析研究,提出了混凝土泵车智能浇注方案,以及需要解决的关键技术。重点研究了泵车臂架运动学,轨迹规划以及虚拟环境生成。应用机器人技术、虚拟现实技术和计算机图形学技术,对混凝土泵车智能浇注过程进行了仿真。以OpenGL为图形驱动,采用Visua1 C 6.0编程,给出了仿真结果。     

对称多型腔粗加工刀轨快速生成算法

对具有对称特性的多型腔零件的刀轨规划方法进行了研究，提出了一种新的算法：首先生成其中一个型腔的刀轨，然后通过阵列生成其余刀轨，并对刀轨的进退刀进行处理，从而快速生成完整的、连续的、有序的刀具轨迹。该算法尤其适用于高速加工的刀轨规划，实践表明，可大大提高编程效率．节省加工时间。