A Petri Net Method for Schedulability and Scheduling Problems in Single-Arm Cluster Tools With Wafer Residency Time Constraints

With wafer residency time constraints for some wafer fabrication processes, such as low pressure chemical–vapor deposition, the schedulability and scheduling problems are still open. This paper aims to solve both problems. A Petri net (PN) model is developed for the system. This model describes when the robot should wait and a robot wait is modeled as an event in an explicit way. Thus, to schedule a single-arm cluster tool with wafer residency time constraint is to decide how long a robot wait should be. Based on this model, for the first time, we present the necessary and sufficient conditions under which a single-arm cluster tool with residency time constraints is schedulable, which can be checked analytically. Meanwhile, a closed form scheduling algorithm is developed to find an optimal periodic schedule if it is schedulable. Also, a simple method is presented for the implementation of the periodic schedule for steady state, which is not seen in any previous work.      

Short-Term Schedulability Analysis of Multiple Distiller Crude Oil Operations in Refinery With Oil Residency Time Constraint

Because of the complexity of a short-term scheduling problem for crude oil operations, some constraints are ignored in modeling the system by the existing approaches, leading to an infeasible solution. To avoid this, the short-term scheduling problem can be studied in control theory perspective by viewing an operation decision in the schedule as a control. With this idea, this paper conducts the schedulability analysis for systems with two and more than two distillers, and the schedulability conditions are presented with the help of Petri net theory. It shows that the number of charging tanks and their capacity, the amount of crude oil of different types in the charging tanks, the oil transportation rate of the pipeline, and the production rate of the system affect the safeness of the system. It also presents the conditions under which the system can reach its maximal production rate. With the safeness conditions and proved results presented in this paper, if a refining schedule is realizable, a feasible detailed schedule for the refining schedule can be easily obtained by creating the operation decisions for the schedule one by one. In the schedule obtained, the starting time of each operation decision can be at any continuous time point, and the schedule is certainly feasible, which overcomes the difficulty faced by techniques that are based on mathematical programming methods.     

时域分析在SAW滤波器芯片测试中的应用

针对晶圆上的芯片在测试中由于一些附加响应信号而导致测试结果与实际器件之间存在的差异，提出时域分析法。利用频域与时域之间相互交换的关系，在时域下通过时间滤波，有选择地保留或扣除一些信号响应，再由傅里叶反变换回到领域测试，这可有效地消除或抑制附加响应对结果的影响，提高芯片测试结果的准确度和可信度，文中同时给出实验过程与比较结果。     

Tools for Performance Analysis and Design of Space–Time Block Codes

Space-time block codes (STBCs) have attracted recent interest due to their ability to take advantage of both space and time diversity to reliably transmit data over a wireless fading channel. In many cases, their design is based on asymptotically tight performance criteria, such as the worst-case pairwise error probability (PEP) or the union bound. However, these quantities fail to give an accurate performance picture, especially at low signal-to-noise ratio, because the classical union bound is known to be loose in this case. This paper develops tighter performance criteria for STBCs which yield considerably better bounds. First, the union bound is developed as the average of the exact PEPs. By noting that some of the terms in the bound are redundant, a second bound is obtained by expurgation. Since this still yields a loose bound, a tighter bound, denoted as the progressive union bound (PUB), is obtained. Because the PUB cannot be computed in closed form, in its most general case, and to avoid computing a high-dimensional numerical integration, its saddlepoint approximation is developed. In addition to the significant improvement of the PUB analysis over other bounding methods, it is also shown that codes designed to optimize the PUB can perform better than those obtained by the looser criteria     

3-D Structure Design and Reliability Analysis of Wafer Level Package With Stress Buffer Mechanism

With the present trend of multifunction and minimizing of size, the conventional electronic package type no longer meets the requirement of the new-generation products. Consequently, new type packaging, based on the wafer level packages (WLPs) and chip scale packages (CSPs) technology are being developed to achieve these requirements, as well as long term reliability. Novel wafer-level chip scale packages (WLCSP) with a stress buffer layer and bubble-like plate (Fig. 1) are proposed in this research to improve the solder joint fatigue life. The thermal stress caused by the coefficient of thermal expansion mismatch can be significantly reduced, and the reliability of the WLP could be substantially enhanced by this new design. In order to realize the relationship of the solder joint fatigue life, stress buffer layer and bubble-like plate, a finite element parametric analysis applying software ANSYS is utilized. In additions, the methodology based on the finite element method (FEM) used in the study has been verified by the relative experiments in our previous researches. The design parameters include the thickness of the stress buffer layer, thickness, bending angle and standoff height of the different types of bubble-like plate. The results of the FEM analysis reveal that the stress buffer layer and bubble-like plate can relax the thermal stresses of solder joints and enhance the package reliability. Besides, the peeling stress between stress buffer layer and two different types of bubble-like plates is discussed, and the stress state of the leadframe is also analyzed in this research. Furthermore, the findings of this research can be used as the guideline for advanced WLCSP design     

Passivity Analysis of Neural Networks With Time Delay

The passivity conditions for delayed neural networks (DNNs) are considered in this paper. We firstly derive the passivity condition for DNNs without uncertainties, and then extend the result to the case with time-varying parametric uncertainties. The proposed approach is based on a Lyapunov–Krasovskii functional construction. The passivity conditions are presented in terms of linear matrix inequalities, which can be easily solved by using the effective interior-point algorithm. Numerical examples are also given to demonstrate the effectiveness of the theoretical results.     

HgCdTe薄片中表面电阻的变化对其总电阻的影响

讨论了 HgCdTe 薄片当其厚度在20μm 左右时,表面与体内导电性质不同所出现的ρ-T 关系曲线,并与正常情况下的ρ-T 关系曲线比较。解释了某些 HgCdTe 薄片电阻率反常的原因。     

晶圆针测技术的异常问题分析与研究

在晶圆探针测试当中,常会由于测试环境或是针测机台参数的改变,使得针痕不正常偏移并打出开窗区,造成测试时的误宰,因而造成公司的损失。文章将就晶圆针测中,由于温度变化所造成的不正常针痕偏移进行分析与研究。     

厚膜电阻器短时过负载破坏性试验阻值变化趋势分析

该文介绍了厚膜片式电阻器短时过载试验时,按不同幅度施加高于规定的试验电压后,电阻阻值变化的情况。结果表明：电阻在过负载的情况下逐步施加不同倍数的额定电压,电阻值将逐渐变小;当施加的电压继续升高,电流开始向绝缘电阻减小的地方集中,所引起的热量将导致电阻体发生破坏,电阻值上升,直至开路。这对分析及预防电阻器在混合电路中发生阻值异常提供帮助。     

Discrete-Time Analysis of Integrated Voice/Data Multiplexers With and Without Speech Activity Detectors

Discrete-time analysis of two schemes for multiplexing voice and data is presented. In each scheme voice and data are multiplexed using the movable boundary frame allocation scheme. In the first scheme, speech activity detectors (SAD's) are not used, and hence, the variations in the voice traffic are only due to the on/off characteristics of voice. In the second scheme, SAD's are employed so that talker silences can he utilized for transmission of additional voice and/or data. In this scheme, the multiplexer performs digital speech interpolation as well as movable boundary frame allocation. The performance measures considered are probability of loss for voice calls, probability of speech clipping, speech packet rejection ratio, and the expected data message delay. In the case of the multiplexer with SAD, a tradeoff exists between data message delay and speech interpolation advantage. Some numerical examples are presented which illustrate the performance of the two multiplexers.     

全自动硅片下料机碎片分析与优化设计

全自动硅片下料机在生产过程中,容易受到刻蚀工艺机台碎片的影响,出现堵片、流片等问题,从而降低良品率。通过分析工艺机台产生的几种碎片形态,提出了加装碎片检测装置和改造下料机翻转结构的解决方案;该方案能及时检测碎片,并通过优化后的结构处理碎片,提高了设备的稳定性。     

ULSI硅衬底片清洗技术的分析研究

本文阐述了ULSI硅衬底片清洗的重要性,介绍了目前世界上采用的各种清洗方法(湿法、干法、超声、激光等)的概况,并通过理论分析及清洗实验研究找出适用于工业规模应用的硅片清洗液和清洗技术.     

硅片研磨表面状态的改善和研磨液的改进

在硅片研磨过程中,由于应力的积累和剧烈的机械作用,硅片表面损伤严重,碎片率增加.介绍了一种改进的研磨液,不但把剧烈的机械作用转变为比较缓和的化学-机械作用,还能起到其他较好的辅助作用并对其各成分作用,进行了理论分析.硅片表面状态得到了一定程度的改善,提高了生产效率.     

Stability Analysis and Practical Design Procedure of Time Delayed Control Systems With Communication Disturbance Observer

In a research field of network-based control systems (NBCSs), the time delay problem is one of the most significant issues. Efficient stabilization methods of time delayed control systems enable NBCSs to be flexibly applied to many kinds of situations. A novel time delay compensation method based on the concept of network disturbance (ND) and communication disturbance observer (CDOB) has been proposed. The compensation method has the same effectiveness as that of the Smith predictor. In addition, since the method is simple and does not need time delay model or time delay measurement, it can be easily implemented to various applications. However, the design method has not been concerned so far. This paper therefore presents stability analysis and studies a practical design procedure of the time delayed control systems with CDOB. At first, the concept of ND is introduced and the validity of the time delay compensation method is described. Then an analysis about the effects of parameters in control systems on stability is conducted. Characteristics of the effects of parameters on stability come out. Then we study a practical design procedure of the time delayed control systems. The validity of the design procedure is validated by experimental results. In the experiment, we also verify the performance of the system in the case of time-varying delay. Finally, comparative study of the method to the Smith predictor is presented.      

Si/GaAs晶圆片键合热应力及其影响因素分析

分别利用Suhir双金属带热应力分布理论和有限元法研究了Si/GaAs晶圆片键合界面在退火过程中的热应力分布,并将热应力分布理论计算结果与有限元分析结果进行了对比验证,得到了一致的结论.根据计算分析结果,对晶圆片进行了结构热变形分析,并研究了不同因素对键合热应力的影响,提出了减小键合热应力的有效措施.     

A Wavelet-Based Approach for Steady-State Analysis of Nonlinear Circuits With Widely Separated Time Scales

We propose a new wavelet method for steady-state analysis of nonlinear circuits. The new method inherits the robustness of wavelet-based technique in handling very strong nonlinear circuits while offering significant reduction of simulation costs for circuits with widely separated time scales     

演播室集群系统设计与分析

为了应对广播电视集团在未来灵活生产以及创新发展的要求,广播电视总台需要具备相对完善、集中、并具有一定规模的演播室集群.集群系统应当包括多种结构系统,如视频系统、音频系统、通话系统等,保障各系统的设计合理性成为一项重要工作,也是充分发挥出演播室集群系统功能的关键.为此,就重庆广播电视集团融媒体中心新闻大厅演播室集群系统设...     

微量铜-铁对硅片表面污染的初步分析

通过比较微量铜铁单独存在和共存时对p型硅片表面的污染，采用电化学直流极化和交流阻抗技术以及SEM、EDX和AES等现代表面分析技术，对未污染和受污染的硅片表面进行了初步的研究．结果表明，当氢氟酸溶液中同时含有ppb水平（1e－9）的铜铁杂质时，不但铜会沉积在硅片表面上发生铜污染，而且还导致硅片表面的碳污染，并从电化学极化电阻、元素深度分布和空间电荷效应等方面对硅片表面铜与碳污染进行了初步的分析和讨论．