基于模糊混合控制的自治水下机器人路径跟踪控制

基于模糊混合控制策略,本文提出了一种用于非线性欠驱动自治水下机器人的鲁棒路径跟踪控制方法.利用Sugeno型模糊推理系统,将PD滑模控制器与非奇异终端滑模控制器光滑连接,构造了模糊混合控制器.它能充分融合这两类控制器的优势,无论系统远离平衡点还是在其附近,都能取得快速收敛的效果.如果,借助于非时间参考量,将该混合控制器用于自治水下机器人路径跟踪控制,将有利于提高它在不确定环境中的跟踪能力.最后,通过仿真计算结果验证了该控制策略的有效性.     

Ti对SiCp/6092铝基复合材料激光焊焊缝组织和性能的影响

采用不同厚度的Ti箔作为填充材料对SiC_p/6092铝基复合材料进行激光焊接,分析不同含量Ti元素对焊缝组织和焊接接头力学性能的影响. 结果表明,Ti箔的加入可以有效改善熔池流动性,从而减少焊缝区的工艺型气孔. 同时,填加Ti箔可以避免激光直接照射在母材上引起的低熔点元素烧损. 在激光的照射下,Ti箔完全熔化并与在热传导作用下部分熔化的母材金属发生冶金反应,Ti元素含量过少时,界面反应得不到有效抑制,焊缝中仍分布有大量的脆性相,Ti元素对焊接接头的力学性能改善不明显;Ti元素含量过多时,Ti元素在熔池中未能扩散开,富余的Ti元素与Al元素反应生成Al₃Ti. 过分长大的Al₃Ti呈片状,将对接头的力学性能不利. 因此,向熔池中加入适量Ti元素有利于改善熔池冶金反应,从而提升接头力学性能,焊接接头的最大抗拉强度可达206 MPa.     

演化信息协助的动态协同随机漂移粒子群优化算法

为了改善随机漂移粒子群算法的群体多样性，通过演化信息的协助，提出动态协同随机漂移粒子群优化（CRDPSO）算法。利用上下文粒子的向量信息，粒子之间的动态协作增加了种群多样性，这有助于提高群体的搜索能力，并使整个群体协同搜索全局最优值。同时在演化过程中的每次迭代，利用二维空间分割树结构来存储算法中的估计解的位置和适应度值，从而实现快速适应度函数逼近。由于适应度函数逼近增强了变异策略，因此变异是自适应且无参数的。通过典型测试函数将CRDPSO算法和差分进化算法（DE）、协方差矩阵适应进化策略算法（CMA-ES）、非重复访问遗传算法（cNrGA）以及三种改进的量子行为粒子群算法（QPSO）进行比较。实验结果表明，不管是对于单峰还是多峰测试函数，CRDPSO的性能均是最优的，证明了该算法的有效性。     

Reflection and Transmission of the Level Step to the Waves in a Linear and Continuous Layer Liquid

1 Introduction Owing to the hot radiation of the sun, the den- sity distribution of water is usually perpendicular in actual oceans and river bayoux. The source of the disturbance will not only produce water waves of a surface mode, but also of an internal mode[1–2]. In layered liquids the internal mode will induce some dynamic water phenomena which are different from those in the single layer liquid[3]. Considering the propagation of waves in deep upheaval terrain, the problem can be simplif…     

Windows CE数据库访问组件的设计与实现

利用Windows CE数据库API接口函数,设计和实现了Windows CE数据库访问组件.提出虚拟系统表的概念,同时结合设计模式的思想,完成对Windows CE数据库的访问管理.在介绍组件模型的基础上,给出了虚拟系统表的具体思路,以及设计模式在隐藏细节方面的应用.     

基于.NET平台的Web系统的构建和实现

针对当今基于.NET平台开发Web系统的主流,为了更有效的发挥.NET平台的优势,提出了在.NET框架下系统结构设计和系统开发过程中应该注意的一些问题,分析了这些问题的原因,并提出了一个可重用的系统框架和一些优化的方法从而实现高效的Web系统和提高系统的整体性能.并结合实际的开发讲述了这些方法的具体的实施过程.通过实际的应用可以证明,提出的系统框架和优化方法是有效的.     

Application of SONQL for real-time learning of robot behaviors

This paper describes the Semi-Online Neural-Q-learning (SONQL) algorithm designed for real-time learning of reactive robot behaviors. The Q-function is generalized by a multilayer neural network allowing the use of continuous states. The algorithm uses a database of the most recent learning samples to accelerate and improve the convergence. Each SONQL algorithm represents an independent, reactive and adaptive state-action mapping, which implements the function of a robot behavior for one degree of freedom (DOF). The generalization capability of the SONQL algorithm was demonstrated by computer simulation with the “mountain–car” benchmark. The SONQL was also investigated by experiment on a mobile robot for a target-following task. Experimental results show that the SONQL is promising for online robot learning.     

A study of axial compression of metallic hemispherical domes

The present paper deals with the experimental and computational analysis of the deformation behaviour of the metallic spherical shells subjected to axial compression. Axial compression of aluminium spherical shells of R/t values ranging from 26 to 45 was performed between two parallel platens. In experiments all the spherical shells were found to collapse in an axisymmetric mode. A finite element computational model of the development of the axisymmetric mode of collapse is also presented. In the proposed finite element model the material of the deforming dome has been idealized as rigid viscoplastic. Experimental and computed results are compared to validate the computational model. Effects of different process parameters on the deformation behaviour of the shells are presented and discussed.     

NUMERICAL SIMULATION OF VISCOUS FLOW AROUND AN APPENDED SUBMARINE MODEL

A multizone/multiblock coupled RANS equation solver is presented to numerically simulate the viscous flow around an appended submarine model at Reynolds number 1. E7. k-ε two equation turbulenc model together with wall function are used. The resulting finite difference equations are solved by SIMPLEC, ADI. The technique of rising up the bottom surface is presented to overcome radial contraction problem in Cartesian coordinate system. Benchmark numerical calculations have been compared with experimental data, the radial distribution of axial velocity on the propeller disk plane is 4. 63%.     

水下爆炸对比格犬损伤试验研究

为研究水下爆炸下水中作战人员的损伤模式和阈值,作者使用试验专用比格犬作为人体替代物,分别开展了克级、千克级TNT水下爆炸试验,直接观察到比格犬在水下爆炸冲击波与气泡脉动作用下的全过程响应,试验结果表明：水下爆炸作用下,含气器官如肺、听器等,遭遇冲击波、气泡、负压等载荷的作用,损伤最为严重,且无论头部是否露出水面,脑部都会产生一定程度的损伤;在同等水下爆炸条件下,潜泳战位比格犬的损伤半径约为泅渡战位的2.5倍;获取了泅渡与潜泳战位比格犬在水下爆炸下的损伤模式和阈值,可为人员水下爆炸冲击伤预测和救治提供参考。