MEMS扫描镜光学性能的圆片级自动检测系统设计

为快速准确地检测出一张硅片上数百个MEMS扫描镜的良品与次品,设计了一种自动测量系统.选用高精度二维位置敏感探测器(PSD)设备,设计其后置硬件电路并编写数据采集的程序.结合经典三角法测量角度的原理搭建自动检测系统,在室温和正常光照条件下,完成了MEMS扫描镜光学性能圆片级自动检测的实验.结果表明:该系统能够快速准确地同时对扫描镜的两个轴进行检测并给出结果.     

扫描电化学显微镜检测电路的研制

采用恒电位仪和仪用放大器设计了一个微电流检测电路,可以有效地将微电流放大输出为模数转换器能够识别的电压信号。该电路性能稳定,非线性误差为±2.4%,也可以应用于其他微电流检测领域。     

Manufacture of a micro-sized piezoelectric ceramic structure using a sacrificial polymer mold insert

There have been technical limitations to manufacture microstructures due to difficulty of demolding during replication process of high aspect ratio microstructure in mass production technologies. In the present study, the fabrication of a novel sacrificial micro mold insert and powder injection molding process using such a micro mold insert is proposed and developed. It utilizes a synchrotron radiation to fabricate the shape of polymer based sacrificial mold inserts and then these mold inserts were exposed at X-ray once more to adjust its solubility. This second X-ray exposure facilitates dissolving of mold inserts instead of demolding process which have difficulties like pattern collapses or defects in case of precise replication process. In this manner, severe problems of demolding process in conventional mass production technologies can be efficiently overcome. To verify the usefulness of the proposed technique, polymer based micro mold inserts with several tens of micrometer sized structure for piezoelectric sensor applications were fabricated using X-ray micromachining process radiated synchrotron. The solubility of mold inserts were optimized by the second X-ray exposure without an X-ray mask and then subsequent powder injection molding process was utilized with a piezoelectric based material. Finally, piezoelectric ceramics with micrometer-scale and high aspect ratio of 5 were successfully fabricated, verifying that the present sacrificial mold system is useful for the precise replication process such as the fabrication of microstructure with high aspect ratio or complicated structure.     

Design and performance evaluation considerations of a multimediamedical database

Multimedia information management and communications systems for medical applications have been undergoing design and development. The aim of these activities has been the development of distributed computer systems providing storage, processing, and communication services required by the medical community. One of the main critical issues of such systems is the handling of multimedia information (i.e., text, images, graphics, and voice) in a uniform way and the fast access to images through the network. We present the design architecture and concepts used in our multimedia database system, along with its performance evaluation. The evaluation focuses on the response times of a multimedia medical database server, as seen by remote workstations for various retrieval and image transfer requests. For this purpose, a queueing network model was developed and simulated. Communications between the workstations and the database server are governed by the client-server model using TCP/IP and appropriate application protocols on a 10 Mb/s Ethernet LAN     

Design and performance analysis of a distributed Java VirtualMachine

This paper introduces DISK, a distributed Java Virtual Machine for networks of heterogenous workstations. Several research issues are addressed. A novelty of the system is its object-based, multiple-writer memory consistency protocol (OMW). The correctness of the protocol and its Java compliance is demonstrated by comparing the nonoperational definitions of release consistency, the consistency model implemented by OMW, with the Java Virtual Machine memory consistency model (JVMC), as defined in the Java Virtual Machine Specification. An analytical performance model was developed to study and compare the design trade-offs between OMW and the lazy invalidate release consistency (LI) protocols as a function of the number of processors, network characteristics, and application types. The DISK system has been implemented and running on a network of 16 Pentium III computers interconnected by a 100 Mbps Ethernet network. Experiments performed with two applications: parallel matrix multiplication and traveling salesman problem confirm the analytical model     

Fabrication and performance of 2-D compound X-ray refractive lenses

Due to the weak refraction of X-rays in matter, a focusing or deflection of X-ray using conventional refractive optics was not feasible. However, since compound X-ray refractive lens (CXRL) with consecutive holes array was proposed, it becomes currently a noticeable issue in X-ray optics. In this paper, we report on fabrication and performance test of two types of PMMA (polymethyl methacrylate) CXRLs. Firstly, one dimensional refractive X-ray lenses of parabolic and circular shape is fabricated by LIGA process. Based on the results, we conduct a fabrication of 2-D CXRLs. Here we suggest a LIGA-self align method which doesn’t need a special align equipment and is simpler method than conventional one. Through performance tests, we show experimentally that CXRLs are novel optical components for the hard X-ray range of about 8 keV and that they have possibilities to apply the X-ray optics for micro-focusing, imaging, and lithography.     

复合机控制系统设计

贴纸铝箔是由铝箔和纸料贴合而成,复合机是目前烟箔生产中一类应用很广泛的设备.本论文从复合机的结构和生产工艺流程入手,对复合机系统的控制部分进行分析,阐述了它的控制系统结构模块,研究了它的张力和温度控制.在此基础上设计了以PLC控制系统为下位机,界面监控的触摸屏为上位机,采用MPI网络通讯的监控系统.     

新型太阳追踪传感器的设计与性能测试

太阳能追踪传感器的性能制约着太阳能跟踪装置的精度和跟踪范围。针对传统光筒式传感器测量范围小、稳定性差等缺点,设计了一种改进型光筒传感器。在室内对传感器的测量范围进行了测试,在室外测试了改进传感器的阈值对跟踪装置的影响。将日梭万年历所计算的太阳高度角和方位角作为参考值。经测试,在12:40~14:40这段时间内,两个传感器的跟踪误差都比较小,传统传感器一天内的平均跟踪误差约为改进传感器的2倍。同时改进传感器很好地解决了光筒高度和测量范围相互制约的问题。     

On the performance of the base-stock inventory system under a compound Erlang demand distribution

In this paper, we propose a new method for determining the optimal base-stock level in a single echelon inventory system where the demand is a compound Erlang process and the lead-time is constant. The demand inter-arrival follows an Erlang distribution and the demand size follows a Gamma distribution. The stock is controlled according to a continuous review base-stock policy where unfilled demands are backordered. The optimal base-stock level is derived based on a minimization of the total expected inventory cost. A numerical investigation is conducted to analyze the performance of the inventory system with respect to the different system parameters and also to show the outperformance of the approach that is based on the compound Erlang demand assumption as compared to the classical Newsboy approach. This work allows insights to be gained on stock control related issues for both slow and fast moving stock keeping units.     

Phase-field simulation of impingement and spreading of micro-sized droplet on heterogeneous surface

A numerical investigation on the impingement and spreading of a micro-sized droplet with nonzero impact velocities on a surface with heterogeneous wettability is presented in this paper. The numerical model was implemented through phase-field simulation with finite element formulation. A simple scheme based on interfacial phase-field function gradient was proposed to track the velocity of contact line which was required to specify the dynamic contact angle based on hydrodynamic theory and molecular kinetic approach. For a circular pattern with a higher wettability than the surrounding surface, the impinging droplet final spread diameter decreases with an increasing wettability contrast. The droplet conforms to the circular patterns with smaller diameters up to a threshold, which is dictated by the wettability of the surface surrounding the pattern. Impact velocity of the droplet affects the maximum spread diameter but not the final conformability to a wettability pattern. Impingement and anisotropic spreading of a droplet on a stripe pattern was also demonstrated in a three-dimensional simulation. The high wettability contrast between the inner and outer regions of the stripe pattern confines droplet spreading and elongates the droplet in the direction of the stripe. These simulations demonstrated the conditions for a jetted micro-sized droplet to be confined to a specific area through wettability patterning, which can potentially improve the precision of current inkjet printing technology.     

单总线温度湿度复合传感器的设计

利用集成湿度传感器HiH3610测得相对湿度,用多功能芯片DS2438获得工作电压和温度补偿数据,采用AT89C52单片微机进行误差补偿计算,设计了一种新型单总线温度、湿度复合传感器。并完成了人机接口和PC机通信。该传感器湿度测量范围为0～100%RH,准确度为±2%RH;温度测量范围为-40～125℃,准确度为±0.5℃。     

Design and performance of mid-ranging controllers

Mid-ranging control applications are multivariate and often involve input constraints. Although some strategies have been reported to work well in industry, no systematic comparison has ever been made. The purpose of this report is to compare these schemes to a model-based predictive control (MPC) approach designed specifically for constrained multivariable control problems. The results indicate that although there are special cases where the existing schemes work reasonably well, MPC is best able to solve the problem in the general case.     

一种高性能MEMS气体流量传感器设计

使用MEMS技术研制出一种高灵敏度热温差式流量传感器。器件采用热隔离性能良好的衬底挖空结构,且热敏电阻器与热源距离可调,保证了系统的灵敏度和响应速度。同时热敏电阻器、加热电阻器与电桥电阻器集成在传感器片内,提高了系统的稳定性。实验表明:合适的电阻器间距可以获得较高的灵敏度,而在0~20 mL/min的量程范围内系统线性度较好,因此,在生化检测、医疗等领域具有良好的推广前景。     

一种高性能的功放控制器设计

CMOS控制器是射频功放模组的重要单元,它为射频功放提供稳定的偏置点和简单的逻辑控制。采用复用误差放大器和补偿电容的结构,设计出一种高性能的应用于WCDMA手机功放模组的功放控制器。电路采用TSMC 0.25μm标准CMOS工艺实现,芯片尺寸为840μm×440μm。模式切换时间小于1.5μs,1 GHz下的PSRR小于-10 d B。测试结果表明:输出电压均值为2.894 V,标准差为17 m V,温度系数为-370 ppm/℃,良率为94%。     

Analyzing the performance of conformational search programs on compound databases

We have studied the sampling performance of conformational search programs using geometric and energetic criteria. Ideally, a conformational search algorithm should identify the largest possible number of low-energy structures (energy criterion) covering the widest possible range of molecular shapes (geometric criterion). Geometric analysis consisted in comparing the distribution of conformations within the generated ensembles by multidimensional scaling and by analysing the eigenvalue structure of the pairwise coordinate covariance matrices. The energetic comparison was carried out by assessing the energy distribution of conformers after minimizing them all using the same semi-empirical quantum mechanics optimization protocol. The present investigation focused on five conformational search programs: DGEOM, QXP, ROTATE, LMOD and OMEGA. We have applied these methodologies to a maximally diverse 604-compound subset of the LeadQuest library. The program LMOD performs best according to the energetic criterion, whereas a wider range of geometrically diverse conformations is sampled by the other programs, at the cost of higher median conformer energies. In terms of speed, OMEGA is fastest. We recommend the use of LMOD or OMEGA for high-quality conformational search applications.     

Quantitative assessment of effects of visual scanning on concurrent task performance

Much of the research in visual scanning has adopted a single task experimental paradigm. The characteristics of visual scanning in multi-task situations are largely unknown. A quantitative assessment of the effects of visual scanning on concurrent task performance was gained from two experiments. Subjects were required to perform a simulated driving task, which involved a primary pursuit tracking task and a discrete response task. The response task was one of simple information acquisition in the first experiment and of complex information integration in the second. The information acquisition task required subjects to search for a spatial or verbal target. The information integration task required them to search for a spatial or verbal target and then make a rule-based decision by integrating the information carried by current and previous targets. The two types of task involved either spatial or verbal material, whose location was displayed with 4 levels of spatial uncertainty. The results of the two experiments which were: 2 (single/dual task) × 2 (spatial/verbal material) × 4 (levels of uncertainty of target location) revealed unique characteristics of visual scanning in multi-task performance. The effects of visual scanning on task performance and subjective workload were more pronounced in the dual task conditions than in the single. Increases in scanning demand produced greater interference with a concurrent spatial task than with a verbal one when the location uncertainty of visual scanning was sufficiently high. Implications for multi-task human-machine interface design are discussed.     

基于MEMS技术的复合型智能传感器设计

把微机电系统(MEMS)技术的加速度敏感元件和微处理器有机结合,借助智能算法,设计了一种多功能的复合传感器,可同时测量运动物体的的振动、冲击和倾斜角度。试验表明:该传感器能够足够同时精确地检测运动物体的振动、冲击和倾斜角度信息,用于汽车中时,能够及时检测汽车的动态信息与车体的姿态。     

Design and performance evaluation of a portable parallel libraryfor space-time adaptive processing

Space-time adaptive processing (STAP) refers to a class of methods for detecting targets using an array of sensors. Various STAP methods use similar operations on different data or in different orders. We have developed a portable, parallel library of subroutines for prototyping STAP methods. The subroutines work on the IBM SP2 and the Intel Paragon under three different operating systems and three different communication libraries, and can also be configured for other systems. We provide execution-time models for predicting the performance of each subroutine. Using the library routines, we created a parallel version of element-space pre-Doppler processing, three parallel versions of higher-order post-Doppler processing, and two versions of PRI-staggered post-Doppler processing. We implemented a fourth version of higher-order post-Doppler processing, the hybrid method, which uses a combination of fine-grain and coarse-grain parallelism to reduce execution time. The hybrid method can be used to improve performance when a large number of processors is available. Our execution time models generally predict the best method and predict execution times to within 10 percent or better for large test cases