Extracting Behavioral Data from Physical Descriptions of MEMS for Simulation

The work described here deals with the problems of modeling and simulation for MEMS devices. The eventual goal is to produce a top-down MEMS design system similar to today's powerful VLSI design systems. In this work a fixed fabrication process (MUMPS) and a fixed layout tool (L-Edit) are chosen. Thus our efforts are concentrated on reliable simulation of designs and eventual comparison with actual fabricated parts. The cantilever beam is chosen as an example of how extraction from a physical layout may be modeled and interfaced with various simulators.     

S－域行为描述的模拟集成电路综合方法

本文提出了一种通用的、从Ｓ－域传输函数入手进行模拟集成电路结构级综合的方法，并详细地讨论了提高电路性能和合格率的电路技巧。此外，本文还给出了生成物理版图的一点建议，本文采用该方法完成了切比雪夫滤波器的综合，ＳＰＩＣＥ模拟结果表明该方法是可行的。     

Extracting Sea Ice Data from Satellite SAR Imagery

With the prospect of operational satellite SAR's by the end of the decade, there is a clear need to develop automated algorithms for the extraction of geophysical data about sea ice from highresolution radar imagery. To this end, we have developed techniques for distinguishing ice from open water and for resolving the details of deformation within areas 100 km square imaged by Seasat SAR. The classification of ice and open water is based on the creation of a second band of image data consisting of the local variance of the original brightness, the first band being a local average brightness. In the space of these two variables, ice and open water are separated into two distinct clusters. The deformation is found on a 3.4-km mesh by local cross correlations of the brightness. The strategy is to find a coarse displacement field with a highly averaged image, and to proceed through a hierarchy of images with increasing resolution, improving the accuracy of the displacements at each step. Comparison with manually determined displacement shows room for improvement in regions of high deformation by using smaller areas for cross correlation. The concentration and deformation data are used together to determine localized regions of the scene where open water is produced or lost.     

Finding and Extracting Data Records from Web Pages

Many HTML pages are generated by software programs by querying some underlying databases and then filling in a template with the data. In these situations the metainformation about the data structure is lost, so automated software programs cannot process these data in such powerful manners as information from databases. We propose a set of novel techniques for detecting structured records in a web page and extracting the data values that constitute them. Our method needs only an input page. It starts by identifying the data region of interest in the page. Then it is partitioned into records by using a clustering method that groups similar subtrees in the DOM tree of the page. Finally, the attributes of the data records are extracted by using a method based on multiple string alignment. We have tested our techniques with a high number of real web sources, obtaining high precision and recall values.     

一种从采样数据中提取信号频率的方法

首先，提出了一种从采样数据中提取信号频率的方法；其次，通过相对误差计算公式给出了此种方法的相对误差，且在matlab环境下验证了此种算法并给出了仿真结果，对从采样数据中提取信号频率的研究有一定的参考意义。     

Physical Modeling of MEMS Variable Inductor

In this study, we propose a new equivalent circuit model of variable inductors. We have proposed variable inductors with metal plate moving with a microelectromechanical system (MEMS) actuator. The proposed model consists of a conventional single-pi model, networks for silicon substrate and metal plate flowing eddy current, and coupling coefficients between these networks. The model is verified by fitting with measured data. Error in inductance and value is less than plusmn5%.     

MEMS湿度传感器信号采集与数字化处理研究

MEMS（微电子机械系统）湿度传感器是利用标准的CMOS技术加上MEMS的后处理技术制造,以其体积小、响应快等优点受到越来越多的重视,介绍了本实验室研制的MEMS压阻式湿度传感器的测试原理、硬件电路的设计和传输函数模型的建立,以及软件设计和封装设计,最后给出了样机的测试结果。     

Extracting High-Level Information from Location Data: The W4 Diary Example

Services for mobile and pervasive computing should extensively exploit contextual information both to adapt to user needs and to enable autonomic behavior. To fulfill this idea it is important to provide two key tools: a model supporting context-data representation and manipulation, and a set of algorithms relying on the model to perform application tasks. Following these lines, we first describe the W4 context model showing how it can represent a simple yet effective framework to enable flexible and general-purpose management of contextual information. In particular, we show the model suitability in describing user-centric situations, e.g., describing situations in terms of where a user is located and what he is doing. Then, we illustrate a set of algorithms to semantically enrich W4 represented data and to extract relevant information from it. In particular, starting from W4 data, such algorithms are able to identify the places that matter to the user and to describe them semantically. Overall, we show how the context-model and the algorithms allow to create an high-level, semantic and context-aware diary-based service. This service meaningfully collects and classifies the user whereabouts and the places that the user visited.

基于ACIS的MEMS工艺几何仿真的关键算法

针对微机械系统(MEMS)工艺几何仿真提出了一种算法,该算法通过设置实体模型上表面的实体和高度两个属性,解决了MEMS工艺几何仿真中产生的多个实体模型之间相对位置定义的问题。该算法在工艺几何仿真系统中的实现表明,使用此算法后,系统运行稳定可靠,仿真速度快。     

Hierarchical Mixed-Domain Circuit Simulation, Synthesis and Extraction Methodology for MEMS

Emerging results for mixed-domain circuit simulation, a component-level synthesis strategy, and a layout extractor is presented for use in design of microelectromechanical systems (MEMS). The mixed-domain circuit representation is based on Kirchhoffian network theory. Micromechanical and electromechanical components may be partitioned hierarchically into low-level reusable elements. The MEMS component-level synthesis approach uses optimization to generate microstructure layout that meets specified performance criteria. A feature-recognition based extractor for verification translates layout geometry into the mixed-domain circuit representation. A common MEMS component, the integrated microresonator, demonstrates the use of these tools. Lumped-parameter MEMS simulation of the resonant frequency matches finite-element analysis to 1% and fabricated resonators match to within 4% of the synthesized performance. Based on this initial work, a hierarchical structured design methodology for integrated microsystems that is compatible with standard VLSI design is proposed.     

引信MEMS延时保险机构性能仿真分析

引信保险机构是否具有延时功能以区分后坐跌落和发射两种不同环境是引信保险机构的关键性能指标之一。基于MEMS制造工艺,结合引信安保机构安全性能的设计准则,提出了一种具有延时解保功能的MEMS引信保险机构。采用动力学仿真软件对后坐机构在跌落(15 000g和20 000g两种情况,300μs)和发射(10 000g,10ms)两种环境下的运动和动态特性进行仿真,并分析其结果曲线。结果表明,该保险机构在垂直跌落情况下(最不利的情况)不会解保,在发射后坐力的作用下则可安全解除保险,证明了该MEMS引信保险机构具有延时解保功能并且可以有效区分跌落和发射两种不同环境。     

MEMS镍平面弹簧非线性力学性能仿真及研究

工程应用中,平面微弹簧存在弹性系数的非线性现象且难以被忽略,弹簧结构的几何非线性是引起这种现象的主要原因。针对特定形状的弹簧运用Ansys软件进行了非线性有限元静力学仿真,计算出弹簧弹性力F与弹性形变x之间的对应关系,并与采用MEMS微细加工技术制得弹簧样品实测实验结果比较,相对误差低于3.2%,验证了分析模型的可靠性。而后设计了5种不同平面形状的微弹簧,仿真计算它们的力学性能曲线,以及改变弹簧臂宽度厚度后的力学性能曲线,分别进行比较以讨论影响非线性的主要因素,为弹簧的设计工作提供参考依据。     

RF MEMS开关失效因素的COMSOL仿真

针对RF MEMS开关的可靠性问题,利用有限元软件COMSOL,对悬臂式RF MEMS开关周围的电场分布,开关上的电荷分布和本征频率进行了分析;并研究了在静电场和结构力场耦合作用下悬臂梁的内应力情况,找出开关损坏的可能部位,探索RF MEMS失效的机理,为悬臂式RF MEMS开关的优化改进提供理论依据。     

一种MEMS热驱动可变电容的分析模拟

文中设计并分析了一个MEMS热驱动可变电容,它的下极板固定于衬底,上极板通过热致动器驱动。热致动器由冷臂和热臂组成,一端通过锚点固定于衬底,一端连接在电容器上极板。热驱动器通过电压驱动使MEMS电容器上极板上下运动。文中作者使用有限元方法模拟了150～300μm加热臂长在0～4 V电压条件下的电容变化值和温度变化,有限元模拟结果表明其电容变化率最大可达10倍。     

低压驱动RF MEMS开关设计与模拟

RF MEMS开关存在驱动电压高、开关时间长等问题,利用ANSYS对电容式开关加以改进,设计扭转臂杠杆与打孔电容膜相结合的新型开关。通过静电耦合与模态分析的仿真,可以在理论上改善RF MEMS开关的射频性能,并有工艺的可行性。     

终端式MEMS微波功率传感器的结构模拟

在工艺流程以及材料选择的基础上,用Coventorware和HFSS对间接加热终端式MEMS微波功率传感器进行了模拟与设计。模拟结果包括共面波导(CPW)与终端电阻上的温度分布,以及热电堆的接近对CPW性能的影响。确定了热偶对数为50,热电堆与CPW之间的距离为50μm,并选择了GaAs和Au作为热电偶的两臂,TaN作终端电阻。     

高阶兰姆波MEMS声表面波谐振器仿真研究

以有限元法为基础,对高阶兰姆波型微机电系统(MEMS)声表面波谐振器进行了仿真。研究了压电材料及其厚度、Si基底厚度对高阶兰姆波声速的影响规律,结果表明,AlN压电薄膜器件的高阶兰姆波的声速比ZnO和LiNbO3器件更大。压电材料较薄时传播兰姆波,太厚时则传播瑞利波。高阶兰姆波的声速随着硅基底厚度增加而逐渐降低,并趋于一个稳定值。在此基础上,提出了在电极上方加载一层压电薄膜来提高兰姆波声速的器件结构,仿真结果表明,通过增加一层AlN薄膜,可提高高阶兰姆波的声速,进而提高器件的谐振频率。     

一种开环流水线A/D转换器的系统仿真

介绍了一种开环(Open-Loop)流水线结构的A/D转换器的行为级仿真.通过对系统结构的分析,对影响系统性能的主要参数以及非线性因素进行了深入研究,提出了对系统的主要模块进行数学建模和仿真方法.搭建了测试平台,对一个8位、250MHz采样频率的开环流水线结构A/D转换器进行了理想情况仿真,验证了系统结构,并通过对加入非理想因素后的系统仿真,得出一组满足实际系统设计要求的性能指标.     

基于分形理论的MEMS光开关微镜分析与模拟

微镜是微电子机械系统(MEMS)光开关的关键结构,镜表面粗糙度对微镜反射率、插入损耗等特性影响重大.给出了用扫描隧道显微镜测量的一组微镜的表面形貌,进而将分形理论应用在微镜表面的分析上,同时一种三维的Weierstrass-Mandelbrot(W-M)函数被用以模拟各种不同的表面形貌.结果对比表明,这种W-M函数可用于微镜表面的建模和形貌分析.