非等概率条件下多货叉结构堆垛机作业周期研究

基于非等概率条件下多货叉结构堆垛机的存取策略、多货叉结构堆垛机作业周期的数学模型、自动化立体仓库货架的长高比和堆垛机作业速度对堆垛机作业周期影响对多货叉结构堆垛机的作业周期及仓库的出入库能力进行研究,并得出结论。     

自动化立体仓库双梭堆垛机作业时间及系统吞吐性能

分析了堆垛机作业时间的影响因素及系统吞吐性能;建立了多种情况下双梭堆垛机作业时间期望和方差的数学模型以及多种情况下双梭堆垛机自动存取系统的作业周期数学模型。     

烟丝原料立体仓库堆垛机出入库作业优化研究

为了提高烟丝原料立体仓库堆垛机的作业效率,解决多台堆垛机作业不均衡问题,提出了以各堆垛机作业时间总和最小与作业时间均衡为目标的出入库作业优化模型.在该模型中,用出入库优化作业的规则替代原有作业规则.为了寻求最佳的出入库货位序列,该模型通过构建货位坐标系,采用堆垛机在全速和减速运行状态下联合作业和单作业两种模式的作业时间计算方法,提高了出入库的作业效率.在相同参数下,对一个具体烟丝立体仓库实例进行了作业优化前后的比较.结果表明,通过采用优化作业方法,作业效率每小时可以提高82个烟包,各堆垛机的作业不均衡性大为减小.     

非等概率条件下自动化立体仓库出入库周期计算

在非等概率条件下,建立计算堆垛机平均单作业周期和平均复合作业周期的数学模型,利用C＋＋语言编制了计算自动化立体仓库堆垛机作业周期的程序,并在Visual C＋＋6．0编辑器上调试通过,实现了非等概率条件下堆垛机作业周期的求解。     

转弯堆垛机效率分析与验证

转弯堆垛机在自动化立体仓库系统中的应用越来越广泛,但对其效率方面的研究还比较少。首先是在各个货位存取概率一样的情况下分析转弯堆垛机复合作业过程;然后结合转弯堆垛机的运动特性等得到其效率计算模型,代入运动参数计算出作业效率;最后通过AutoMod仿真软件对计算出的作业效率进行验证,结果表明:利用公式推导计算得到的作业效率值与通过AutoMod仿真得到的作业效率值基本能够吻合,可以通过本计算模型去计算转弯堆垛机的单一作业效率和复合作业效率。     

基于粒子群算法的立体仓库系统堆垛机作业路线优化

运用粒子群算法优化立体仓库系统堆垛机作业路线。实际应用证明,该算法用于自动化立体仓库系统堆垛机作业路线优化是有效可行的。     

基于遗传算法的巷道堆垛式立体车库路径优化

为减少巷道堆垛式立体车库堆垛机运行距离,提高立体车库整体运行效率,提出了一种基于遗传算法的堆垛机路径优化方案。通过对立体车库的结构特点以及车辆存取过程的分析,建立堆垛机复合作业模式和单一作业模式的数学模型,以最短路径为目标,利用改进的遗传算法对堆垛机的存取车序列进行优化,并与传统的存取车作业方式进行对比,结果表明遗传算法可以明显减少堆垛机的运行距离,得到更加合理的存取车路径,为立体车库选择合理的调度策略提供理论参考。     

基于四自由度的铝锭堆垛机械手的结构设计与运动学分析

针对传统的铝锭堆垛作业方式存在的问题,研制了一种具有搬运与堆垛功能的机械手。根据堆垛作业的需要,建立了四自由度铝锭堆垛机械手的运动系统,给出了其结构设计方案,采用D-H方法建立了机械手的运动学方程,并讨论了该机械手的运动学问题,为机械手的动力学分析、控制及轨迹规划的研究提供了可靠的依据。     

自动化立体仓库堆垛机拣选作业调度研究

将堆垛机拣选作业调度归纳为旅行商问题，并从遗传算法角度，研究了求解堆垛机拣选作业调度最优路径的具体方法。经过仿真试验验证，这一方法完全可行。     

非等概率条件下转弯型堆垛机平均作业循环周期的计算

转弯型堆垛机是自动化立体仓库中实现货物自动存取的关键设备。本文首先分析了转弯型堆垛机不同的作业情形,推导出非等概率条件下转弯型堆垛机单一作业和复合作业的循环周期计算公式,提出使用遍历算法求解平均作业循环周期方法,并探讨了按照ABC分类优化货位的方案,最后对华南理工大学仓储实验室的数据进行了相关的实例分析与研究。研究成果为企业自动化立体仓库的运营规划和高效管理提供了决策依据。     

热声制冷机板叠性能指标数值计算与遗传算法优化

板叠是驻波热声热机的重要部件,直接影响热声热机的效率。针对驻波热声制冷机,构造了一个板叠性能指标的数值计算方法及其优化设计方法。分析基于短板叠近似理论的计算方法的局限,构造迭代数值方法同时求解制冷量、压力、体积流率、平均温度分布以及温度梯度等参数,从而计算出板叠性能指标;基于该迭代方法探讨了热声板叠长度、宽度、位置、阻塞率以及温差等与板叠性能指标之间的关系;以板叠长度、宽度、位置、阻塞率为优化设计变量,板叠性能指标为优化目标,利用遗传算法,对驻波热声制冷机板叠进行了优化设计。与基于短板叠近似理论的方法相比,由于考虑了更多的实际因素,该方法数值计算结果更为准确,优化设计结果更容易被接受。     

基于PLC的铝锭堆垛机器人控制系统的设计

结合铝锭的堆垛作业,采用S40MA型PC机,设计了铝锭堆垛机械手模型的控制系统,确定了I/O点分配及控制系统总图,并给出了总梯形图。这种技术同样适用于其它工业机器人控制系统。     

Issues related to the modeling of solid oxide fuel cell stacks

This work involves a method for modeling the flow distribution in the stack of a solid oxide fuel cell. Towards this end, a three dimensional modeling of the flow through a Solid Oxide Fuel Cell (SOFC) stack was carried out using the CFD analysis. This paper examines the efficacy of using cold flow analysis to describe the flow through a SOFC stack. It brings out the relative importance of temperature effect and the mass transfer effect on the SOFC manifold design. Another feature of this study is to utilize statistical tools to ascertain the extent of uniform flow through a stack. The results showed that the cold flow analysis of flow through SOFC might not lead to correct manifold designs. The results of the numerical calculations also indicated that the mass transfer across membrane was essential to correctly describe the cathode flow, while only temperature effects were sufficient to describe the anode flow in a SOFC.     

Mechanisms of accelerated degradation in the front cells of PEMFC stacks and some mitigation strategies

The accelerated degradation in the front ceils of a polymer electrolyte membrane fuel cell（PEMFC） stack seriously reduces the reliability and durability of the whole stack. Most researches only focus on the size and configuration of the gas intake manifold, which may lead to the maldistribution of flow and pressure. In order to find out the mechanisms of the accelerated degradation in the front cells, an extensive program of experimental and simulation work is initiated and the results are reported. It is found that after long-term lifetime tests the accelerated degradation in the front cells occurs in all three fuel cell stacks with different flow-fields under the U-type feed configuration. Compared with the rear cells of the stack, the voltage of the front cells is much lower at the same current densities and the membrane electrode assembly（MEA） has smaller active area, more catalyst particle agglomeration and higher ohmic impedance. For further investigation, a series of three dimensional isothermal numerical models are built to investigate the degradation mechanisms based on the experimental data. The simulation results reveal that the dry working condition of the membrane and the effect of high-speed gas scouting the MEA are the main causes of the accelerated degradation in the front cells of a PEM fuel cell stack under the U-type feed configuration. Several mitigation strategies that would mitigate these phenomena are presented： removing cells that have failed and replacing them with those of the same aging condition as the average of the stack; choosing a Z-type feed pattern instead of a U-type one; putting several air flow-field plates without MEA in the front of the stack; or exchanging the gas inlet and outlet alternately at a certain interval. This paper specifies the causes of the accelerated degradation in the front cells and provides the mitigation strategies.     

Note: A heated-air curtain design using the Coanda effect to protect optical access windows in high-temperature, condensing, and corrosive stack environments

We present an air knife design for creating a heated air curtain to protect optical infrared access windows in high-temperature, condensing, and corrosive stack environments. The design uses the Coanda effect to turn the air curtain and to attach the air curtain to the window surface. The design was tested and verified on our 24 m stack and used extensively over a 6 yr period on several release stacks. During testing and subsequent use no detrimental changes to access window materials have been noted. This design allows stack monitoring without significantly affecting the stack flow profile or chemical concentration.     

Measuring the surface area of a cell by the method of the spatial grid with a CSLM—a demonstration

The spatial grid is a method for estimating the surface area of particles. A stack of perfectly registered sections is the essential prerequisite for its use. The confocal scanning light microscope provides such a stack by optical sectioning. The spatial grid method is briefly described and applied to an osteocyte lacuna in dry mineralized human mandible. This type of cell was chosen because of its very complex shape. The variance of the area estimate is studied and compared with the results of a simulation.     

一种紧凑型压电叠层直线电机驱动足的优化设计

在使用压电叠层时一般会设计防剪切机构,未设计防剪切机构时需要对驱动足结构进行仿真设计,减小压电叠层所受剪切力。为此,提出在无防剪切机构时电机驱动足的结构优化方法,并对一种紧凑型压电叠层直线压电电机驱动足进行仿真优化。通过优化把横向压电叠层输出端的旋转变形由1.333μm减小至0.061μm,纵向平移变形由1.911μm减小至0.749μm,机构的最大等效应力由253.35MPa减小至189.68MPa,显著改善了压电叠层的工作环境。提出一种并联S形弹簧机构,给出该结构的优化设计方法并进行仿真设计。仿真结果表明:该机构有较大的刚度范围,可以有效降低压电叠层所受剪切力;在相同刚度的情况下,具有弹簧宽度越大最大等效应力越小的特点。     

Assembly Tolerance Stack Analysis for Geometric Characteristics in Form Control – the "Catena" Method

Tolerance stack analysis involving geometric characteristics is usually difficult as it involves numerous rules and conditions. Users need to acquire an adequate knowledge of geometric dimensioning and tolerancing before making any attempt at the computation of tolerance stack analysis problem. Conventional stack form methods are very widely used in tolerance stack analysis, but the computation requires tedious work with numerous rules to remember that often complicate the problem and confuse the user. A need therefore arises to simplify the tolerance stack methodology. This paper presents a straight forward, easy-to-use graphical approach known as the "Catena" method for tolerance stack analysis, involving geometric characteristics in form control – flatness, straightness, circu-larity and cylindricity. Three examples are given to illustrate the effectiveness of the proposed method. No complicated mathematical formulae are required in deriving the solution.     

Estimation of individual feature surface area with the vertical spatial grid

The area of an individual bounded surface (e.g. the boundary of a properly sampled cell) can be estimated from an isotropic uniform random stack of parallel sections, or of non-invasive planar scans, using the well-known spatial grid. A standing problem was to estimate the area of an individual bounded surface with an arbitrary degree of accuracy from a vertical (i.e. not isotropic) stack of sections or scans. A new tool to do this, called the ‘vertical spatial grid’, is presented.     

基于硬件协议栈芯片的高速以太网接口设计

随着现代数据采集系统和测试系统对信息传输速率的更高要求,网络化数据传输成为未来发展的趋势。采用Xilinx公司的XC5VLX50型FPGA和硬件协议栈芯片W5300开发了一种以太网接口,结构简单、易于实现。给出了以太网接口的硬件设计,阐明了硬件协议栈芯片初始化、端口初始化以及数据传输的软件实现;并对读写寄存器时序进行了详细阐述。实验表明该设计能够稳定的进行数据传输,实现了FPGA和上位机之间的通信。