一种新型四阶S型轨迹规划算法的研究与应用北大核心CSCD

提出了一种四阶S型运动轨迹规划的新方法,根据给定参数计算得到最大速度三阶导数作用时间,最大加加速度作用时间和最大加速度作用的时间,通过循环计算的方式得到加速阶段所运动的距离与速度,以加速阶段所达到的速度作为最大速度计算得到最大速度作用的时间.此时,由浮点型转整型数据所产生的误差也可以在其最大速度的匀速阶段得到补偿,最后,减速阶段的数据由S曲线加减速控制中速度曲线的对称性得到.该算法在基于倍福PLC的三动子运料平台中进行了验证,实验表明,提出的S型运动轨迹规划算法在不用过多保存曲线数据的情况下也能获得平滑的速度和加速度,有效地提高了系统的柔性,同时简化了算法的实现,大大地节省了PLC的资源.     

立方准晶压电材料的半空间问题北大核心CSCD

考虑了立方准晶压电材料的半空间问题.给出了反平面机械载荷和面内电载荷作用下立方准晶压电材料弹性问题的控制方程,结合半无限区域表面边界条件,利用算子理论和复变函数方法获得了立方准晶压电材料半空间问题一般解的表达式.基于一般解得到了集中线力作用下,半空间问题的声子场和相位子场的位移、应力以及电位移的解析表达式.     

模糊度量空间的强嵌入北大核心CSCD

本文定义了George和Veeramani意义下的模糊度量空间的强嵌入,证明了可强嵌入的模糊度量空间能够粗嵌入到Hilbert空间.另外还证明了强嵌入在模糊度量空间的粗范畴下是不变的,并给出了模糊度量空间强嵌入的一些等价刻画.     

模空间上的多线性乘子估计北大核心CSCD

给出了模空间上多线性乘子新的估计,改进了已知结论,并把所得结果应用于微分方程非线性项的估计.     

时间周期的离散SIS模型的传播动力学北大核心CSCD

该文研究了一类具有时间周期的空间离散多种群SIS模型的传播力学.首先,借助周期单调半流的传播速度与行波理论,证明了渐近传播速度c*的存在性.其次,利用比较原理,证得了渐近传播速度即为单调周期行波解的最小波速.     

偏序偏度量空间中有理分式型广义弱压缩的公共不动点结果北大核心CSCD

在偏序完备偏度量空间中研究了四个映射的公共不动点问题,对满足某种带有理分式项的广义弱压缩条件的四个映射得到了一些公共不动点结果.证明了公共不动点唯一的一个充分条件,并给出一个例子予以说明.最后讨论了在同伦问题中的一个应用.     

非参数空间滞后模型的广义矩估计北大核心CSCD

放松了参数空间滞后模型中自变量的影响为已知的线性或非线性形式假设,考虑一类非内生自变量为随机变量的非参数空间滞后模型,构建了该模型的广义矩估计法,导出了其估计量的渐近性质,用Monte Carlo模拟方法考察了估计量的小样本表现.此外还将所提出的估计方法应用于估算我国各省市全要素生产率增长率.     

加权复合算子在两类函数空间之间的序有界性北大核心CSCD

本文首先研究了加权复合算子W_(Φ,φ)(f):=Φfoφ的Hilbert-Schmidt性质与序有界性的对应关系.接着利用加权Dirichlet空间D^(q)_(β)(0相似文献   

Banach空间上变分不等式问题的新投影算法北大核心CSCD

本文在Banach空间上提出一种关于伪单调变分不等式问题的新算法.在对参数强加适当的条件下,我们证明由算法生成的序列强收敛到变分不等式的一个元素,所得结果推广和提高了很多最新结果.     

基于白噪声的网络传染病模型动力学分析北大核心CSCD

该文基于确定性网络传染病模型,建立了白噪声影响下的随机网络传染病模型,证明了模型全局解的存在唯一性,利用随机微分方程理论得到了传染病随机灭绝和随机持久的充分条件.结果表明,白噪声对网络传染病传播动力学有很大的影响,白噪声能有效抑制传染病的传播,大的白噪声甚至能让原本持久的传染病变得灭绝.最后,通过数值模拟验证了理论结果.     

Trajectory Modeling of Robot Manipulators in the Presence of Obstacles

This paper presents two different strategies for the problem of the optimal trajectory planning of robot manipulators in the presence of fixed obstacles. The first strategy is related to the situation where the trajectory must pass through a given number of points. The second strategy corresponds to the case where only the initial and final points are given. The optimal traveling time and the minimum mechanical energy of the actuators are considered together to build a multiobjective function. The trajectories are defined using spline functions and are obtained through offline computation for online operation. Sequential unconstrained minimization techniques (SUMT) have been used for the optimization. The obstacles are considered as three-dimensional objects sharing the same workspace performed by the robot. The obstacle avoidance is expressed in terms of the distances between potentially colliding parts. Simulation results are presented and show the efficiency of the general methodology used in this paper.     

超布朗运动:质量过程的极限行为及值空间的扩张

本文给出了超布朗运动的质量过程在不灭绝条件下的极限分布的拉普拉斯变换的具体形式,并得出了在较一般的分支特征下使其值空间从M_F（R^d）扩张到M_P（R^d）的一个充分条件．     

Global State Space Approach for the Efficient Numerical Solution of State-Constrained Trajectory Optimization Problems

A new approach based on a global state space form is introduced for solving trajectory optimization problems with state inequality constraints via indirect methods. The use of minimal coordinates on a boundary arc of the state constraint eliminates severe problems, which occur for standard methods and are due to the appearance of differential-algebraic boundary-value problems. Together with a hybrid approach and a careful treatment of some interior-point conditions, we obtain an efficient and reliable solution method.     

Dynamic Reaction of a Composite Anisotropic Space with Tunnel Holes to the Action of Concentrated Shear Forces

An antiplane stationary dynamic problem of elasticity theory for a two-component anisotropic (orthotropic) space is considered, where one component of the pair is weakened by tunnel holes of arbitrary cross section. The space is subjected to the action of time-dependent harmonic shear forces concentrated along some line and shear stresses applied to the surfaces of the holes. To solve the problem, the fundamental solution for a composite space without holes is preliminarily constructed. Using integral representations for displacements in the composite space with holes, the boundary problem of elasticity theory is reduced to an integral equation of second kind, which is solved numerically by the method of quadratures.     

On the Complete Convergence of Moving Average Process with Banach Space Valued Random Elements

Let {Y _i ;−∞<i<∞} be a doubly infinite sequence of independent random elements taking values in a separable real Banach space and stochastically dominated by a random variable X. Let {a _i ;−∞<i<∞} be an absolutely summable sequence of real numbers and set V _i =∑ _k=−∞^∞ a _i+k Y _i ,i≥1. In this paper, we derive that if and E|X| ^μ log  ^ρ |X|<0, for some μ (0<μ<2, μ≠1) and ρ>0 then for all ε>0. This work was partially supported by the Korean Research Foundation Grant funded by the Korean Government (KRF-2006-353-C00006, KRF-2006-251-C00026).     

弹性薄板和薄扁壳及其在半空间上接触问题解的唯一性证明

用Laplace方程的第一种内边界问题不可能有两个不同的解这一定理,证明了弹性薄板和薄扁壳及其在半空间上接触问题解的唯一性问题。第二类内边界问题唯一性也得到证明。