面向复杂地形的四足机器人步态生成方法

为实现四足机器人在凹凸地形上稳定运动并能选择最大步长的目的,提出了基于稳定裕度的步态规划方法。基于研究对象,建立四足机器人的运动学方程及逆运动学方程,将机器人足端的位置映射为各关节的关节变量;提出工作空间矩阵的概念,将所需克服的地形高度反映到工作空间矩阵中,并选择最优步态区域;依据四足机器人的立足点在质心坐标系下的空间坐标,以纵向稳定裕度为约束条件,在工作空间矩阵中计算机器人摆动腿的最大步长并规划机械腿的运动轨迹;针对所提出的方法,分别利用MATLAB和ADAMS进行仿真验证。在MATLAB环境中计算并验证质心的水平投影是否在立足点形成支撑多变形内,而ADAMS平台分析机器人在复杂地形上的位移变化及姿态变化。仿真结果表明机器人的质心始终在支撑多边形内,机器人的躯干姿态基本保持不变且运动速度匀速,所提出的方法能够保证机器人稳定行走,为四足机器人的稳定运动提出依据。     

具有不耐烦顾客和多重工作休假的排队库存系统

研究具有不耐烦顾客和多重工作休假的M/M/1/N排队库存系统模型,分别考虑了系统中库存为零时服务员休假和系统中顾客数为零时服务员休假两种休假方式,基于(s,S)库存策略,运用矩阵迭代方法得到了系统稳态概率分布,并给出系统相关性能指标,进而建立系统平均库存费用函数.通过数值算例对比分析了两种休假方式下的系统主要参数变化对...     

一类时变预警可休假系统解的存在惟一性分析

研究了一类修理工可多重延误休假且带预警装置的简单可修复系统,其中系统的失效率和修理工的延误休假率均与系统的运行时间有关.首先运用概率分析的方法将系统模型表示为一组积-微分方程,然后将系统方程转化为一个Banach空间中的抽象半线性发展方程的初值问题,并利用C_0半群理论讨论了系统解的存在惟一性条件.     

Numerical simulation on magnetic confinement characteristics of internal vortex electrostatic cyclone precipitator under different working voltages

Aiming at improving the capture performance of internal vortex electrostatic cyclone precipitator (ECP), a theoretical model with mechanics-electric-magnetic coupling was established, the collection efficiency of magnetic confinement ECP under different working voltages was simulated, and the influence of magnetic flux intensity on the removal performance of submicron particles was explored. Results show that the number of particles escaped from the cyclone is greatly reduced after the introduction of magnetic field and electric field, indicating that charging effect and magnetic confinement are more conductive to trap submicron particles in the internal vortex ECP. The lower the working voltage is, the worse the charging lifting effect is, but the stronger the magnetic confinement characteristics are. Furthermore, the contributions of charging effect to collection efficiency and magnetic confinement characteristics are more obvious at a weaker magnetic flux density. The research results can provide a practical new idea for the innovative design of ECP.     

水中二氧化碳含量对弱碱性阴树脂工作交换容量影响的研究

弱碱性阴树脂用于水的除盐处理时，其工作交换容量的大小与许多因素有关。本文主要就进水中ＣＯ２含量对弱碱阴树脂工作交换容量的影响进行了研究，得出了弱碱性阴树脂工作交换容量受水中ＣＯ２含量影响的一般规律，这为弱碱性阴树脂的应用提供了依据。     

The M/G/1 queue with disasters and working breakdowns

In this paper, we analyze the M/G/1 queueing system with disasters and working breakdown services. The system consists of a main server and a substitute server, and disasters only occur while the main server is in operation. The occurrence of disasters forces all customers to leave the system and causes the main server to fail. At a failure instant, the main server is sent to the repair shop and the repair period immediately begins. During the repair period, the system is equipped with the substitute server which provides the working breakdown services to arriving customers. After introducing the concept of working breakdown services, we derive the system size distribution and the sojourn time distribution. We also obtain the results of the cycle analysis. In addition, numerical works are given to examine the relation between the sojourn time and the some system parameters.     

A deteriorating system with its repairman having multiple vacations

This paper considers a repairable system with a repairman, who can take multiple vacations. If the system fails and the repairman is on vacation, it will wait for repair until the repairman is available. Assume that the system cannot be repaired “as good as new” after failures. Under these assumptions, using the geometric process and the supplementary variable technique, some important reliability indexes are derived, such as the system reliability, availability, rate of occurrence of failures, etc. According to the renewal reward theorem, the explicit expression of the expected profit per unit time is obtained. Finally, a numerical example is given to illustrate that there exists an optimal replacement policy N∗, which maximizes the value of the expected profit rate after a long time run.     

Second moment relationships for waiting times in queueing systems with poisson input

For theM/G/1 queue there are well-known and simple relationships among the second moments of waiting time under the first-in-first-out, last-in-first-out, and random-order-of-service disciplines. This paper points out that these relationships hold in considerably more general settings. In particular, it is shown that these relationships hold forM/G/1 queues with exceptional first service,M/G/1 queues with server vacations, andM/G/1 queues with static priorities.     

Experimental approach to assess sorptive loss properties of volatile organic compounds in the sampling bag system

In this study, the sorptive loss patterns for volatile organic compounds were evaluated by gaseous standards containing 13 compounds (benzene, toluene, styrene, p‐xylene, methyl ethyl ketone, methyl isobutyl ketone, isobutyl alcohol, butyl acetate, acetaldehyde, propionaldehyde, butyraldehyde, isovaleraldehyde, and valeraldehyde). The gaseous standards, prepared initially at two contrasting concentration levels (40 and 4000 ppb) in a polyester aluminum bag, were measured after two consecutive transfers into empty bags. It indicates that the percent loss patterns, if assessed for all 13 target compounds, are affected most sensitively by the initial concentration levels of samples to yield 2.62 ± 2.22% (at 40 ppb) and 9.57 ± 6.74% (at 4000 ppb). Moreover, the sorptive loss patterns at high concentration samples (4000 ppb) tend to increase in relation with increasing molecular weight of target compounds, although such pattern disappears in low concentration samples (40 ppb). The observed loss patterns, if evaluated in relation to some key parameters like concentration or compound type, suggest the possibility that the sorptive loss of target compounds in storage media can occur in a predictable manner.     

The discrete-time MAP/PH/1 queue with multiple working vacations

We consider a discrete-time single-server queueing model where arrivals are governed by a discrete Markovian arrival process (DMAP), which captures both burstiness and correlation in the interarrival times, and the service times and the vacation duration times are assumed to have a general phase-type distributions. The vacation policy is that of a working vacation policy where the server serves the customers at a lower rate during the vacation period as compared to the rate during the normal busy period. Various performance measures of this queueing system like the stationary queue length distribution, waiting time distribution and the distribution of regular busy period are derived. Through numerical experiments, certain insights are presented based on a comparison of the considered model with an equivalent model with independent arrivals, and the effect of the parameters on the performance measures of this model are analyzed.