Point-to-point and collision avoidance control of the motion of an autonomous bicycle

This work deals with the stabilization and collision avoidance control of a riderless bicycle (see Figure 1). It is assumed here that the bicycle is controlled by a pedalling torque, a directional torque, and by a rotor mounted on the crossbar that generates a tilting torque.Given two points r_A, r_B, and a circular obstacle in the horizontal plane. Also, given a time interval [0, t_f], where 0 < t_f < ∞. It is shown here that by applying a kind of inverse dynamics control, the motion of the bicycle is stabilized while simultaneously controlling its speed and direction in such a manner that the point of contact between the bicycle's rear wheel and the horizontal plane will be able, during [0, t_f], to move from r_A to r_B without hitting the obstacle.     

一种求解圆形下料问题的快速算法

本文研究圆形件优化排样算法,目的是提高材料利用率。本文提出了一种新的放置算法(圆弧搜索算法,ASA),与文献中算法相比,ASA在较短的时间内产生了可以和排样领域著名的法国学者Hifi在SCI和EI检索刊物中提出的较复杂方法GA-BH在利用率方面相媲美的效果;对随机生成例题的计算结果表明,本文算法的计算时间可以满足一般实践应用的要求,所得排样方案的材料利用率较高。     

Slope stability analyses on a low-cost microcomputer

A slope stability program for use on a low-cost microcomputer is described. The program is general in that it includes circular and noncircular slip surface analyses, different soil strata, a watertable, and external loading. The graphics facilities available on the machine are used extensively to produce an interactive program which is easy to understand and run.     

Application of the chebyshev-fourier pseudospectral method to the eigenvalue analysis of circular mindlin plates with free boundary conditions

An eigenvalue analysis of the circular Mindlin plates with free boundary conditions is presented. The analysis is based on the Chebyshev-Fourier pseudospectral method. Even though the eigenvalues of lower vibration modes tend to convergence more slowly than those of higher vibration modes, the eigenvalues converge for sufficiently fine pseudospectral grid resolutions. The eigenvalues of the axisymmetric modes are computed separately. Numerical results are provided for different grid resolutions and for different thickness-to-radius ratios.     

圆形槽波导中径向盘对阻抗的影响

应用时域有限差分法(FDTD)计算圆形槽波导中径向盘直径、厚度、位置对输入阻抗的影响。用非均匀网格和三角形网格来近似计算圆形槽波导的圆弧形金属边界附近的场值,用细网格计算径向盘中的场值,用完全匹配层(PML)模拟圆形槽波导的开放边界。最后由电压和电流的离散傅立叶变换的比值得到随径向盘直径、厚度、位置变化的输入阻抗。     

小型多馈源宽频微带天线分析与设计

本文着重研究了提高轴比带宽的方法。从多馈源实现圆极化的机理出发,从理论上分析证明了采用多馈源技术可有效展宽轴比带宽。在小型微带贴片天线上,设计馈电网络,采用探针馈电,为贴片提供等幅、相位相差90°的激励,形成圆极化。仿真及实测结果表明,这种天线与单馈点天线相比,展宽了轴比带宽,提高了低仰角不圆度指标。     

An analytic solution for a fault tree with circular logics in which the systems are linearly interrelated

A circular logic or a logical loop is defined as the infinite circulation of supporting relations due to their mutual dependencies among the systems in the fault tree analysis. While many methods to break the circular logic have been developed and used in the fault tree quantification codes, the general solution for a circular logic is not generally known as yet. This paper presents an analytic solution for circular logics in which the systems are linearly interrelated with each other. To formulate the analytic solution, the relations among systems in the fault tree structure are described by the Boolean equations. The solution is, then, obtained from the successive substitutions of the Boolean equations, which is equivalent to the attaching processes of interrelated system's fault tree to a given fault tree. The solution for three interrelated systems and their independent fault tree structures are given as an example.     

Delamination in elastic shear deformable circular layers

This work extends the analytical solution of an interface crack in straight layered structures to circular layered structures. A small segment at the vicinity of an interface crack tip in a circular laminated beam is analyzed by a novel shear deformable bi-layered circular beam theory. Two concentrated forces are found existing at the crack tip due to the requirement of the equilibrium condition. Closed-form solution of the total energy release rate of the interface crack is obtained as the half of the product of the concentrated forces and the corresponding displacement gradient discontinuities at the crack tip. Closed-form expressions of the mode I and II components of the energy release rate are also obtained by global and local methods. Numerical verifications are conducted by analyzing the interlaminar delamination of a circular beam with an edged crack and comparing with the baseline results obtained through finite element analysis. Excellent agreements between the present method and finite element analysis on the predictions of total energy release rate and mode partition verify the accuracy and efficiency of the present solution.     

改进的基因拷贝数变异检测算法

cnvPartition算法在单核苷酸多态性数据上运算时间复杂度较高。为此,提出一种改进的基因拷贝数变异(CNV)检测算法。将二元分割与cnvPartition算法相结合,优先查找显著变异断点,再检测出隐藏性变异断点。实验结果表明,该算法在位点数增加时,最高可提高50%的检测速度,利于检测出小片段的CNV变异。