Modularized simulation for lot delivery time forecast in automatic material handling systems of 300 mm semiconductor manufacturing

The more accurate the forecast is to lot delivery time, the more effective it is in fab scheduling. In fab operations, scheduling is the major impact factor of tools capacity allocation, tools utilization control and bottleneck management. However, there is no effective method to estimate delivery time in 300 mm automatic material handling systems (AMHS) operation. Computer simulations are authentic, but they are either too complex to model fab operations as well as the whole AMHS, or too time-consuming to simulate with a full-scaled fab model. This paper proposes an analytic methodology to estimate the loop-to-loop delivery time for differentiated lots in a 300 mm AMHS environment. Combining simulation and statistics techniques, we develop a modularized simulation method (MSM) for delivery time forecast of priority lots. Numerical experiments based on data from a local 300 mm manufacturing fab are conducted. Simulation demonstrates that the MSM has credible results in estimating lot delivery times. The time differences between MSM and simulation for both priority lots and regular lots are 0.2 s and 0.1 s, respectively. Using the MSM method to forecast AMHS delivery time is a great contribution for streamlining shop floor operations, such as scheduling and dispatching, for eliminating time delays in the 300 mm automatic environment.     

Two-machine flowshop scheduling to minimize mean flow time under simple linear deterioration

A real industrial production phenomenon, referred to as deteriorating jobs, has drawn increasing attention. However, most research on this issue considers only single-machine problems. Motivated by this limitation, this paper considers a simple linear deterioration model in a two-machine flowshop where the objective is to minimize the mean flow time. Several dominance rules and three lower bounds are proposed to speed up the search for an optimal solution, and several heuristic algorithms are provided to derive near-optimal solutions. In addition, a computational experiment is conducted to evaluate their performances. Results indicate that the algorithms perform well, and a combined heuristic algorithm is recommended for practitioners.     

Effect of conversion of functional layout to a cellular layout on the queue time performance: some new insights

Transition from a functional system to a cellular system involves partitioning the machine and part populations. Partitioning the machine population degrades the queue time performance. This paper investigates whether splitting the part population into part families can offset the effect of partitioning the machine population on queue time. Queue times are obtained for both cellular and functional systems through queueing theory for single stage production and by simulation for multistage production under identical factor settings of process time, setup time, batch size and part arrival. Unlike past research, this study identifies certain situations where a cellular system without getting benefits in factor settings outperforms a functional system.     

特种制造业准时制用户驱动生产系统研究

通过对特种制造业基于准时制的用户驱动型制造系统的研究，提出了适应于客户驱动的以模块化设计、另部件标准化、系列化为基础；以合作供应为主要管理要素的准时生产运行管理模型，给出基于准时制的用户驱动型制造系统在特种制造行业——电梯制造业中的应用。     

Estimation of the mean caliper: A new simple approach

Morphometric measurements are commonly carried out on structures the shape of which approximates that of a sphere. We calculated some stereological data of eosinophil granules by using digitized planimetry, performed on transmission electronmicrographs. By using a new approach for mean caliper (D) estimation and extrapolating an approximate granule axial ratio, we were able to calculate the granule density size. We deduced from a numerical analysis for various sphere sizes distributions from which an underestimation of not more than 4% may be contributed to D in most cases, assuming that the diameter coefficient of variation is less than 35%. The methodology we propose for mean ellipsoid caliper estimation seems to be useful in cases in which the disector method is not suitable.     

Time evaluation for the steady state condition of the weight before the measurements

The temperature difference between the weight and its surrounding is an important parameter in the evaluation of the waiting time required by the weights to reach a steady state condition before starting a measurement, because the thermal gradients cause the thermal convection effect on the mass during the weighing process. In this study, investigation of both theoretical and experimental applications were carried out to evaluate the steady state condition of the weight before the calibration. Two kinds of unsteady state heat conduction equation were introduced, theoretical calculation results were compared to experimental results, and comparisons were very satisfactory for a 20 g weight. Then theoretical calculations were extended for different initial temperatures and for different weights. It was realized that the steady state condition of the waiting time was less dependent on initial temperature, but greatly dependent on the sizes of the weights.     

Modeling and real time simulation of an HVDC inverter feeding a weak AC system based on commutation failure study

This paper presents modeling and study of 12-pulse HVDC (High Voltage Direct Current) based on real time simulation where the HVDC inverter is connected to a weak AC system. In goal to study the dynamic performance of the HVDC link, two serious kind of disturbance are applied at HVDC converters where the first one is the single phase to ground AC fault and the second one is the DC link to ground fault. The study is based on two different mode of analysis, which the first is to test the performance of the DC control and the second is focalized to study the effect of the protection function on the system behavior. This real time simulation considers the strength of the AC system to witch is connected and his relativity with the capacity of the DC link. The results obtained are validated by means of RT-lab platform using digital Real time simulator Hypersim (OP-5600), the results carried out show the effect of the DC control and the influence of the protection function to reduce the probability of commutation failures and also for helping inverter to take out from commutation failure even while the DC control fails to eliminate them.     

Scheduling of FMSs with information delays: A simulation study

Practitioners and academicians throughout the world recognize the crucial role played by flexibility within manufacturing organizations, especially those engaged in small batch manufacture. However, although the concept of flexibility has begun to attract increased attention, its interaction with information integration and automation has not captured due attention. For example, it almost always has been assumed that a real-time control mechanism is available for exploiting routing flexibility on the shop floor. While this may be true for FMSs, it generally is not so for the vast majority of conventional manufacturing systems with varying levels of information integration and automation. The lack of a fully integrated and automated control mechanism within such semi-automated flexible manufacturing systems (SAFMSs) would eventually cause delays in the availability of shop status information. In this paper, we study the impact that defined modes of information delay have on the performance of a hypothetical SAFMS through detailed simulation experiments. Given that the level of routing flexibility is a controllable design parameter, our interest is in determining the impact that information delays have on decisions pertaining to the selection of appropriate levels of routing flexibility. To highlight the impact of information delays within the SAFMS, the Taguchi experimental design procedure is adopted as a performance evaluation and analysis vehicle, using makespan as a measure of performance. Simulation results indicate the presence of a system specific tolerance limit, operation below which minimizes performance loss.     

机构运动方案仿真系统的研究

分析了仿真在机构运动方案设计过程中的意义和发展过程 ,仿真将成为机械设计系统中不可缺少的有力工具。结合虚拟现实技术 ,提出了一个基于数据库和 3D图形库的机构运动方案仿真系统的基本结构。它能实现对复杂设计方案的三维实时生成和运动仿真控制 ,完成对机构的运动分析和干涉检查。系统具有面向对象的思想和开放的结构 ,扩充方便     

单轴燃气轮机建模与仿真研究

本文分析了几种现在公认的燃气轮机模型的特点,评述了当前燃气轮机建模研究的进展,并指出了它的发展方向.     

The two-stage assembly flowshop scheduling problem with bicriteria of makespan and mean completion time

In this paper, we address the two-stage assembly flowshop scheduling problem with a weighted sum of makespan and mean completion time criteria, known as bicriteria. Since the problem is NP-hard, we propose heuristics to solve the problem. Specifically, we propose three heuristics; simulated annealing (SA), ant colony optimization (ACO), and self-adaptive differential evolution (SDE). We have conducted computational experiments to compare the performance of the proposed heuristics. It is statistically shown that both SA and SDE perform better than ACO. Moreover, the experiments reveal that SA, in general, performs better than SDE, while SA consumes less CPU time than both SDE and ACO. Therefore, SA is shown to be the best heuristic for the problem.     

时域波形再现技术在汽车道路模拟中的应用

时域波形再现技术是一种获得整车在实测道路上的载荷时间历程的方法,对于汽车的可靠性研究和汽车零部件的疲劳寿命设计具有重要作用,通过对传统试验手段的对比,介绍了时域波形再现技术的原理和工作流程,并对其中的关键技术——系统识别和目标模拟进行了简要介绍。     

Computer simulation and experimental study of machining deflection due to original residual stress of aerospace thin-walled parts

Aerospace thin-walled parts have a complex structure and high accuracy. Factors such as original residual stress, fixing, and machining may make low-rigidity parts deform easily, which is difficult for traditional craftwork to forecast and control. Especially in machining big aerospace parts, original residual stress has a great effect on machining deflection. In this paper finite element model of original residual stress is established to analyze the corresponding deflection by machining aerospace thin-walled parts. Simulation results are validated consistent with experimental results approximately. At last the paper puts forward the corresponding mend methods to control the deflection caused by original residual stress during the actual machining process.     

汽车振动系统的虚拟样机仿真及试验研究

应用面向整体系统的虚拟样机的概念,将研究对象分解为多个子系统,设计车辆行驶的路面特性文件和轮胎特性文件,建立某型空气悬架客车的虚拟样机仿真模型,进行平顺性仿真。结合试验,测试车身上相应位置的加速度值,然后利用编制的计算软件,计算加权加速度均方根值。将理论计算与实车的道路试验进行对比研究表明,仿真结果和实测结果接近,一定程度验证了所建立的多体动力学模型的正确性,对于产品的开发与改进具有一定的指导价值。     

基于Simulink实时工具的小卫星姿控物理仿真

针对小卫星姿态控制系统的设计和研制需要,应用高精度单轴气浮台模拟小卫星在轨运行时的微重力、无摩擦的环境,借助Simulink模块库建立了实时控制系统软件模型,利用反作用飞轮、光纤陀螺、数显表、控制计算机等物理设备快速构建了简化的小卫星姿态控制仿真硬件系统,并进行了姿态控制物理仿真实验,实验结果表明,仿真系统具有较高的姿态指向精度和稳定度,能够达到小卫星姿态控制仿真要求。     

磁流变阻尼器设计及实时控制研究

设计了基于混合工作模式的小型磁流变阻尼器,并分析了其力学特性.针对阻尼器的时间响应要求,设计了一种高精度PWM电流驱动器,采用PI控制算法改善电流响应时间.仿真结果表明,电流响应快,精度高,达到稳态值的95%所需的时间约为0.3毫秒.并通过对实物进行试验,得到相应的关系曲线.     

From natural to biomimetic: The superhydrophobicity and the contact time

The superhydrophobicities and the contact time of lotus leaf and reed leaf were investigated. The results indicated that both lotus leaf and reed leaf have good superhydrophobic properties, and the water contact time was 12.7 and 14.7 ms on the surface of lotus leaf and reed leaf, respectively. Surface structure plays a key role in the different contacting times. Homogeneous distribution of papillae on the surface of lotus leaf was more helpful to reduce the contact time than anisotropic groove‐shape on the surface of reed leaf. Based on the bionics coupling theory, the bionics sample possessing similar lotus‐leaf‐like surface structure on the aluminum alloy was designed and fabricated successfully. The water contact angle was about 153 ± 2°, sliding angle less than 5°, and the water contact time was 13.4 ms on the surface of bionics sample, which presented excellent superhydrophobic property, and achieved the aim of bionic design. Microsc. Res. Tech. 79:712–720, 2016. © 2016 Wiley Periodicals, Inc.     

一类切换模糊PID控制器设计及其仿真

提出了一类高动态性能切换模糊PID控制器设计方法.通过对传统PID控制中比例控制和微分控制作用的分析,结合模糊PID控制器鲁棒性能和自适应性好的优点,设计了一类新的模糊控制器.由于该类控制器先后经历比例控制,微分控制和模糊PID控制的切换,使被控系统不仅具有一般模糊PID控制器的所具有的良好的鲁棒性能和自适应性,而且与一般模糊控制器相比具有更小的超调量和调节时间,是一类动态性能良好的控制器.最后将该控制器应用于一伺服系统进行仿真对比,并给出了Simulink仿真框图.仿真结果说明了该控制器的优越性.     

高线集卷站回转台传动系统的设计及其控制仿真研究

芯棒集卷站回转平台传动系统的稳定运转对整个高速线材生产线至关重要,其精确有效地控制具有非常重要的意义.对高线集卷站回转平台传动系统进行了设计研究,并对其控制系统进行了分析,建立其MATLAB仿真模型,对其进行仿真试验,结果表明了系统的可行性和有效性.