机械臂运动路径设计问题

针对机械臂运动的逆问题,提出了无障碍空间的牛顿迭代算法.并对牛顿迭代法进行了改进,建立了有障碍空间中避碰问题的一般模型,并对问题进行了求解.对于求出的机械臂指尖的姿态,先采用最大步长调整,再对剩余部分采用一次微调的方法生成指令序列,使生成的序列尽可能的短.针对具体问题①,给出了达到目标点的一个指令序列,步数为89步,精度为0.179mm;对于问题②,离散化裂纹,应用大步长调整的牛顿迭代法,给出了一个运动序列,实现了避碰焊接,各点的平均精度达到0.188mm,并对最低点附近在1mm误差范围内不可达到的区域进行了讨论,用解析和仿真的方法证明和验证了最低点不可达;对于问题③,改进了避碰问题的一般模型和算法,用试探法实现了四个焊接点的无碰焊接,并对圆台内表面在1mm误差范围内不可焊接的区域进行了分析.     

面向对象的BESⅢ探测器模拟系统

BESⅢ探测器的模拟软件包BOOST, 是基于Geant4开发的面向对象的模拟软件. BOOST全面地模拟了BESⅢ探测器的物质和几何结构, 给出了粒子在各个子探测器中的击中信息, 以ASCII码文件的形式输出原始数据和MC truth信息可供重建软件开发和物理分析使用, 初步结果显示BOOST的模拟是合理的.     

机械臂运动路径设计问题

主要运用最优化的思想对机械臂运动路径的设计问题进行了讨论.首先利用空间几何知识,得出了机械臂末端的空间位置与各关节角度间的关系,然后就不同问题进行具体分析后分别建立了最优化模型并设计了相应算法,根据模型和算法并采用逐步缩小搜索范围等方法对各个问题进行了求解.最后,从提高机械臂灵活性和扩大其适用范围方面提出了改进建议.     

On the Influence of the Indices of Normalizers of Sylow Subgroups on the Structure of a Finite p-Soluble Group

We study the dependence of the structure of finite p-soluble groups on the indices of normalizers of Sylow subgroups. We obtain estimates for the p-length of these groups, and for small values of indices we find the nilpotent length of a soluble group.     

Upper Bounds on List Star Chromatic Index of Sparse Graphs

A star k-edge-coloring is a proper k-edge-coloring such that every connected bicolored subgraph is a path of length at most 3.The star chromatic indexχ'_st(G)of a graph G is the smallest integer k such that G has a star k-edge-coloring.The list star chromatic index ch'st(G)is defined analogously.The star edge coloring problem is known to be NP-complete,and it is even hard to obtain tight upper bound as it is unknown whether the star chromatic index for complete graph is linear or super linear.In this paper,we study,in contrast,the best linear upper bound for sparse graph classes.We show that for everyε>0 there exists a constant c(ε)such that if mad(G)<8/3-ε,then■and the coefficient 3/2 ofΔis the best possible.The proof applies a newly developed coloring extension method by assigning color sets with different sizes.     

石墨烯吸附Al2Cl6分子的第一性原理与Monte Carlo研究

采用第一性原理与蒙特卡罗方法研究Al₂Cl₆气体分子在石墨烯表面的吸附性能与光电性质，结果表明：(1)石墨烯对Al₂Cl₆气体分子具有较强的物理吸附作用，两个Al原子的连线与石墨烯平面近乎平行且两个Al原子处于紧靠顶位的桥位位置时最稳定；(2)温度升高不利于Al₂Cl₆气体分子吸附并存在阶跃式降低，气体逸度增加有利于吸附并存在阶跃式升高，Al₂Cl₆气体分子插入石墨/双层石墨烯/多层石墨烯宜将温度维持在AlCl₃沸点附近，并增加气体的压力；(3)Al₂Cl₆的吸附对石墨烯的电子结构进行了调控，但没有明显改变石墨烯费米能级附近的态密度以及“赝能隙”;(4)Al₂Cl₆的吸附对体系光学参数的影响十分明显，静态介电常数提高近5倍，使体系屏蔽效应有较大增强，在长波波段的吸收性能、反射性能及光电导也有了明显提升.     

Facile way of dynamically tailoring microporous structures in polyvinylidene fluoride films prepared by thermally induced phase separation

Polyvinylidene fluoride (PVDF) films were prepared via thermally induced phase separation (TIPS) using diphenyl carbonate as the diluter in an attempt to disclose the competitive relationship between crystal growth and droplet growth during phase separation process. By varying the quenching temperature different temperature gradient fields were established, which were theoretically evaluated via enthalpy transformation method. The effects of polymer concentration and quenching temperature on evolution of hierarchical morphologies in TIPS films were systematically investigated. According to the morphological characteristics, the cross-sectional morphology of the films with lower polymer concentration (Φ_P = 25%) could be divided into three layers; while that of higher polymer concentration counterpart (Φ_P = 55%) only presented a bi-layered structure. The reason for this could be ascribed to the effect of cooling rate on both crystal growth and droplet growth during TIPS process, which further determined the formation of the hierarchical structure in microporous films. With an increasing quenching temperature, both pore size and porosity of PVDF films increased, accompanied by an improvement on both thermal stability and dynamic mechanical thermal property. The present study could insightfully supply a facile route to fabricate structure-controllable microporous films of crystalline polymers via an appropriate regulation of the TIPS quenching parameters.     

基于线性调频机制的太赫兹无损检测成像技术

基于全固态电子器件和零中频机制，设计了基于调频连续波的太赫兹无损检测成像系统。所提系统的有效频率范围为9.375～13.75 GHz,经24倍频后自由空间中的频率范围为0.225～0.330 THz。采用单个喇叭天线与定向耦合器结合，实现收发一体，并利用光学透镜组对太赫兹波束进行准直聚焦。对准光系统的波束质量进行了优化，提高了系统的信噪比，确保了在现有参数条件下的最佳空间分辨率。同时，采用相位聚焦的方法对系统进行了非线性矫正，使得深度分辨率接近理论分辨率。系统采用直线扫描和旋转扫描组合的方式，实现了柱坐标三维数据的获取。利用所提系统对高压绝缘端子进行了检测评估，并重构了全视角透视图像，实现了目标三维结构在实空间和像空间的孪生对应。此外，所提系统能够准确地显示绝缘端子内部的异常区域，有助于直观地评估被检测目标的内部状态，进而可以进一步满足工业领域无损检测的需求。     

Screening of Minimalist Noncanonical Sites in Duplex DNA and RNA Reveals Context and Motif-Selective Binding by Fluorogenic Base Probes

We hypothesize that programmable hybridization to noncanonical nucleic acid motifs may be achieved by macromolecular display of binders to individual noncanonical pairs (NCPs). As each recognition element may individually have weak binding to an NCP, we developed a semi-rational approach to detect low affinity interactions between selected nitrogenous bases and noncanonical sites in duplex DNA and RNA. A set of fluorogenic probes was synthesized by coupling abiotic (triazines, pyrimidines) and native RNA bases to thiazole orange (TO) dye. This probe library was screened against duplex nucleic acid substrates bearing single abasic, single NCP, and tandem NCP sites. Probe engagement with NCP sites was reported by 100–1000× fluorescence enhancement over background. Binding is strongly context-dependent, reflective of both molecular recognition and stability: less stable motifs are more likely to bind a synthetic probe. Further, DNA and RNA substrates exhibit entirely different abasic and single NCP binding profiles. While probe binding in the abasic and single NCP screens was monotonous, much richer binding profiles were observed with the screen of tandem NCP sites in RNA, in part due to increased steric accessibility. In addition to known binding interactions between the triazine melamine (M) and T/U sites, the NCP screens identified new targeting elements for pyrimidine-rich motifs in single NCPs and 2×2 internal bulges. We anticipate that semi-rational approaches of this type will lead to programmable noncanonical hybridization strategies at the macromolecular level.