未知环境下机器人障碍物检测技术

未知环境下地面的不平坦性和机器人相对障碍物位姿的不确定性会造成障碍物特征提取困难,为了准确检测障碍物特征,采用3维相机获取机器人周围环境的灰度图像和距离信息。在此基础上,提出基于灰度信息和3维信息的"阈值法"进行障碍物区域的提取,并针对3维信息"阈值法"剔除的地面与障碍物过渡区域过多,以及机器人相对斜坡方位的不确定性引起的障碍物特征检测不准确,提出区域的恢复算法和表面法线坡度计算。实验结果表明,所提出的算法具有简单、有效、准确和鲁棒性强的优点。     

保持边缘特征和增强对比度的图像缩放算法

图像的边缘信息和对比度是影响人体视觉的最主要因素。提出一种能够同时保持边缘特征和增强对比度的图像缩放新方法。通过边缘检测算法、边缘梯度增强以及梯度图的低通滤波算法,得到新的梯度图,再通过求解泊松方程得到重建的图像。由于对图像边缘作了特殊处理,从而避免在图像缩放过程中丢失边缘信息。该方法可以同时保持特征以及增加图像的对比度,从而更好地展现图像的细节。实验结果表明,本文方法能应用于一般图像和医学图像的缩放和增强等应用中。     

高校如何构建校园网网络安全体系

如何构建安全的校园网网络体系,是各个校园网建设者需要考虑并实施的一项重要而特殊的工作。为了保证校园网络正常运行,保证学校教学,工作和学习秩序有序进行,本文结合工作实际,针对校园网网络安全体系的建立,提出多种有效且能具体付诸实施的策略,以期解除网络威胁。     

面向多商户的第三方电子券系统设计与实现

电子券正成为商家促销的一种新技术手段.在一个已有的定制化电子券系统的基础上,针对服务于多商户的应用背景,对系统的需求进行了重新梳理和流程优化,给出了改造后的系统架构.同时,还对新系统的权限管理与访问控制问题进行了重点分析和设计,引入基于角色的访问控制模型,使之能支持面向多商户的管理.     

电子政务数据共享模式研究

互联网的广泛应用,改变了社会公众对政府信息需求的观念。加强电子政务数据共享是社会发展的必然要求。为了保证政务信息的有效共享,实现不同部门不同类型数据的转换和重用,提出了一种新的基于公开密钥基础设施体系构造数据共享模式。在新的数据共享模式中,使用电子凭证替代传统的纸质凭证,增加了行政审批事务办理的快捷性、安全性、低碳环保性。为了进一步提高电子凭证的效率,将其与云计算无缝融合。通过对具体应用案例的分析,表明新的数据共享模式具有安全性、可行性和实用性。     

双参数Bézier曲线的升二次扩展

本文以二次Bernstein基函数为例,首次提出了含双参数基函数的新扩展——αβQ—Bern-stein基函数,此类基函数具有新的特点,即基函数的扩展次数一次性升高两次,且包含了二次多项式和带一个参数的三次多项式基函数的所有性质。基于这组基函数定义了αβQ—Bézier曲线,该曲线也含有参数,具有形状可调性,当α与β取某些值时曲线能达到C4连续或在某个端点处C0连续。最后与含两个参数的升一次Bézier曲线进行比较,该曲线具有调节范围广、灵活性更强的优势。     

基于Cortex-M3的多功能楼宇控制系统网关节点设计

针对目前大多公司的楼宇日常办公耗电无法做到智能节能控制,提出了一种基于多功能网关节点的集中控制解决方案。设计中提出利用基于Cortex-M3的LPC1766作为网关节点,并且集成DHT11温湿度传感器,光线传感器和继电器控制电路等。通过RS485和终端节点通讯并且通过以太网与上位机通讯.最终实现远程楼宇节能控制的三层体系解决方案。     

颗粒增强复合材料中的界面层

本文对氧化铝(Al₂O₃)、氟化钙(CaF₂)和玻璃微珠颗粒填充环氧基(E51环氧—胺固化体系)复合材料的密度和动态力学性能进行了研究。结果发现由于颗粒填料表面和环氧基体的相互作用,从填料表面开始形成了一层致密的聚合物界面层。它的性质与本体树脂有明显的差别。把填充复合材料看成由填料、界面层和树脂本体组成的三元体系,从“临界填料含量”概念出发,求得了界面层的密度,界面层的厚度和界面层的体积分数。     

Nonlinear response of electron-phonon interaction inn-type nondegenerate piezoelectric semiconductors

The nonlinear response of the electron-phonon interaction in nondegenerate piezoelectric semiconductors such asn-type InSb in the presence of a dc magnetic fieldB directed along the propagation of acoustic waves has been studied by using a quantum mechanical treatment. The effect of electron scattering in solids has been taken into consideration, so the electron relaxation time cannot be neglected. The nonlinear nature of the energy band is corrected for, using the Heisenberg equation of motion. It is found that the nonlinear response is proportional to a nonlinear longitudinal conductivity tensor _zzz when acoustic waves propagate parallel to the [111] direction for both piezoelectric and deformation-potential couplings. Numerical calculations for _zzz of n-type InSb at low temperatures are presented. Results show that the nonlinear response decreases rapidly with the sound frequency, and decreases slowly with the dc magnetic field and temperature. Therefore, the electron relaxation time and the nonparabolicity of energy bands play important roles for the electron-phonon interaction due to the piezoelectric and deformation-potential couplings in the microwave region.     

Simultaneous analysis and design optimization of nonlinear response

The optimal structural design requiring nonlinear analysis and design sensitivity analysis can be an enormous computational task. It is extremely important to explore ways to reduce the computational effort so that more realistic and larger-scale structures can be optimized. The optimal design process is iterative requiring response analysis of the structure for each design improvement. A recent study has shown that up to 90 percent of the total computational effort is spent in computing the nonlinear response of the structure during the optimal design process. Thus, efficiency of the optimization process for nonlinear structures can be substantially improved if numerical effort for analyzing the structure can be reduced. This paper explores the idea of using design sensitivity coefficients (computed at each iteration to improve design) to predict displacement response of the structure at a changed design. The iterative procedure for nonlinear analysis of the structure is then started from the predicted response. This optimization procedure is called mixed and the original procedure where sensitivity information is not used is called the conventional approach. The numerical procedures for the two approaches are developed and implemented. They are compared on some truss type structures by including both geometric and material nonlinearities. Stress, strain, displacement, and buckling load constraints are imposed. The study shows the mixed method to be numerically stable and efficient.