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1.
介绍了强电磁脉冲作用下光纤中热量的计算方法,分析了雷电及核电磁脉冲在光纤中由克尔效应及法拉第效应产生的极化面旋转现象,最后阐述了含金属构件的光缆遭受雷电时的感应电压的计算方法。  相似文献   

2.
选择性激光烧结聚苯乙烯粉末成形温度场的数值模拟研究   总被引:7,自引:1,他引:6  
本文以聚苯乙烯材料为例,对SLS成形三维瞬态温度场的分布变化进行数值模拟计算。计算模型中,考虑了材料的热物性参数随温度变化的情况和激光光强分布不均匀的因素。计算结果表明:烧结过程可以分为两个阶段:第一阶段是光照期的热量输入加热阶段,在该阶段内,光照表面的温度迅速升高,使材料处于过热状态,甚至超过材料的分解点,这一阶段完成粉末表面的致密化,但粉床内部的致密效果不是特别明显;第二阶段是光照结束之后的热量传输阶段,在该阶段内,表面材料吸收的热量向四周扩散,一部分通过对流和辐射换热方式散失到周围环境中,另一部分通过热传导的方式向粉床内部传输,促进粉床内部的烧结,这一阶段粉床内部的致密程度显著提高。  相似文献   

3.
大功率LED的热量分析与设计   总被引:2,自引:0,他引:2  
房华  李阳 《现代显示》2007,18(9):67-70
本文分析了大功率LED光源热的产生、传导,依据热阻基本公式推导出比较完整的热阻计算公式和测试方法,并讨论了计算、测试热阻对大功率LED封装设计的实践意义和应用产品的热量处理。  相似文献   

4.
传统的集中分配热量只是按面积收费,这种热量收费制度存在其不合理性。目前国家积极推行的分户热计量收费方式,把每户用热量单独计量并按实际用热量计费,使上述问题得到了有效的解决。为此本文设计并实现了一种基于C8051F340单片机的分户热计量表,并根据以住户供水流量和供暖过程中的温差为依据计算得出住户用热量,具有很强的实践意义。  相似文献   

5.
随着社会的发展,人们越来越注重自己的健康,跑步成为一种方便而又有效的锻炼方式。但是如何知道自己跑了多少步,多远的路程?计步器可以帮助人们实时掌握锻炼情况。它的主要功能是检测步数,通过步数和步幅可计算行走的路程。步幅信息可通过行走固定的距离如20m来计算或是直接输入,高级的计步器还可以计算人体消耗的热量。  相似文献   

6.
推导了微测辐射热计热隔离结构的热量模型,对系统热响应时间和响应率之间的关系进行了分析,在满足系统响应要求下对热隔离结构的热量参数的确定进行了理论分析和探讨,热量参数曲线图提供了直观的参考,并结合实际提出了优化热量参数的方案。  相似文献   

7.
运用数值方法计算方舱内的热负荷和冷负荷来选定空调器,从而使方舱内工作人员和设备处于舒适的状态。分析方舱传热模型,采用有限元技术分析方舱在太阳辐射热量、舱外壁对流换热量和空调状态下舱内壁对流换热量作用下稳态温度场分布情况,从而验证数值计算结果的正确性。计算空调出现故障时,为了不影响设备的工作的可靠性和稳定性,分析出合理的空调维修时间。  相似文献   

8.
大功率器件IGBT散热分析   总被引:2,自引:0,他引:2  
在实际应用过程中,大功率器件IGBT可能因其产生大量的热量而损坏。所以,我们要进行散热计算,计算出最大的散热器到环境温度的热阻,设计成适用的散热器,把热量传导到外部环境,确保大功率器件安全可靠的工作。  相似文献   

9.
为适应新一代的有源相控阵雷达构建开放式的阵面系统,实现可重构、可扩展功能,本文采用“多级模块化”思想设计了一种高集成度立体数字子阵。针对该子阵尺寸小、热量大,热源分散特点,分析热量传递中的热阻,采用两相流均热板对子阵散热进行了设计和计算,对样机进行了热测试和验证,根据测试结果对子阵热传递的热阻和子阵结构进行了优化设计。优化后的子阵验证了大功率电源背板分区设计及多层多通道微波信号垂直互联等关键技术,实现了子阵轻薄化和立体高效散热。  相似文献   

10.
针对土壤热物性参数与热泵运行模式对地埋管换热量的影响进行分析,通过非稳态数值计算方法求解U型垂直埋管周围非稳态温度场的方法,提出按全年运行模拟的平均值作为地埋管每延米换热量的计算方法。并根据模拟结果,确定影响地埋管单位换热量的主要因素。为类似地源热泵系统的优化设计提供一定的参考。  相似文献   

11.
DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.  相似文献   

12.
This paper describes the design and implementation of a hybrid intelligent surveillance system that consists of an embedded system and a personal computer (PC)-based system. The embedded system performs some of the image processing tasks and sends the processed data to the PC. The PC tracks persons and recognizes two-person interactions by using a grayscale side view image sequence captured by a stationary camera. Based on our previous research, we explored the optimum division of tasks between the embedded system and the PC, simulated the embedded system using dataflow models in Ptolemy, and prototyped the embedded system in real-time hardware and software using a 16-bit CISC microprocessor. This embedded system processes one 320 × 240 frame in 89 ms, which yields one-third of the rate of 30 Hz video system. In addition, the real-time embedded system prototype uses 5.7 K bytes of program memory, 854 K bytes of internal data memory and 2 M bytes external DRAM. Koichi Sato is a Ph.D. student in the Department of Electrical and Computer Engineering at The University of Texas at Austin. He earned his B.S. in University of Tokyo, Japan in 1993. He worked for Automotive Development Center in Mitsubishi Electric Corporation where he was involved in lane and automobile recognition in vehicle video processing products such as automatic cruise control and drowsiness detection systems. He enrolled in the current University at 1998 and received an M.S in 2000. In his Master's thesis he worked on human tracking and human interaction recognition. His current work includes velocity extraction using the TSV transform, object tracking, and 3D object reconstruction. Brian L. Evans is a tenured Associate Professor in the Department of Electrical and Computer Engineering at The University of Texas at Austin. His research and teaching efforts are in embedded real-time signal and image processing systems. In signal processing, his research group is focused on the design and real-time software implementation of ADSL and VDSL transceivers, for high-speed Internet access. In image processing, his group is focused on the design and real-time software implementation of high-quality halftoning for desktop printers, smart image acquisition for digital still cameras, and 3-D sonar imaging systems. In signal and image processing, Dr. Evans has published over 100 refereed conference and journal papers. Dr. Evans is the primary architect of the Signals and Systems Pack for Mathematica, which has been on the market since October 1995. He was a key contributor to UC Berkeley's Ptolemy Classic electronic design automation environment for embedded systems, which has been successfully commercialized by Agilent and Cadence. His BSEECS (1987) degree is from the Rose-Hulman Institute of Technology, and his MSEE (1988) and PhDEE (1993) degrees are from the Georgia Institute of Technology. From 1993 to 1996, he was a post-doctoral researcher in the Ptolemy project at UC Berkeley. He is a member of the Design and Implementation of Signal Processing Systems Technical Committee of the IEEE Signal Processing Society, and a Senior Member of the IEEE. He is the recipient of a 1997 National Science Foundation CAREER Award. J.K. Aggarwal has served on the faculty of The University of Texas at Austin College of Engineering since 1964 and is currently Cullen Professor of Electrical and Computer Engineering and Director of the Computer and Vision Research Center. His research interests include computer vision and pattern recognition focusing on human motion. A Fellow of IEEE since 1976 and IAPR since 1998, he received the Senior Research Award of the American Society of Engineering Education in 1992, the 1996 Technical Achievement Award of the IEEE Computer Society and the graduate teaching award at The University of Texas at Austin in 1992. He has served as Chairman of the IEEE Computer Society Technical Committee on Pattern Analysis and Machine Intelligence (1987--1989); Director of the NATO Advanced Research Workshop on Multisensor Fusion for Computer Vision, Grenoble, France (1989); Chairman of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition (1993), and President of the International Association for Pattern Recognition (1992--1994). He is a Life Fellow of IEEE and Golden Core member of IEEE Computer Society. He has authored and edited a number of books, chapters, proceedings of conferences, and papers.  相似文献   

13.
Towards Mobile Ubiquitous Service Environment   总被引:2,自引:0,他引:2  
In this article we present a perspective on future vision of mobile communications and services which is referred to as Mobile Ubiquitous Service Environment (MUSE). Based on analysis of wireless communications and services, we exploit a conceptual model for MUSE via a top-down approach. The conceptual model consists of three major elements: Terminal Service Environment (TSE), Network Service Environment (NSE) and User Identity (UID). The concept of Always the Best Experience (ABE) is addressed as the hinge in design and development such that the user-centric services could be provided automatically and intelligently in the future diverse wireless world Based on these, we further discuss the issues on design and implementation of architecture of future wireless communication system. Requirements for architecture brought by the new features of MUSE are listed. Moreover, we also address several tradeoffs that should be taken into consideration in design. Finally, the deployment challenges for MUSE, such as reflectiveness of system, security and privacy, as well as peer-to-peer AAA are predicted.Ji Yang received PhD degree on Circuit and System, Bachelor degree on Telecommunication Engineering from Beijing University of Posts and Telecommunications (BUPT) in 2002 and 1993 respectively. Currently, he is an associate professor of BUPT, chief technical supervisor of Wireless Technology Innovation Institute, and vice manager of MTlab of Sino-Germany Software Institute. He leads the research on service and application in Future Forum in China. He also made much contribution to the China Communication Standardization Association (CCSA), including the vision of future Mobile Ubiquitous Service Environment, architecture of future B3G mobile terminal, etc. His research interests include architecture design for mobile ubiquitous networks, theory of self-organization, etc.Zhang Ping is now the professor of Beijing University of Posts and Telecommunications and director of Wireless Technology Innovation (WTI) Institute, BUPT. He has also served on the senior member of C3G Group, China MOST 863 future mobile communication FuTURE project, vice-chairman of China FuTURE Forum, and member of Vision Committee of World Wireless Research Forum(WWRF), he was vice chair of WWRF in 2005. He is also invited as the consultants for many domestic and oversea communication companies. He is very active on the international research activity on Beyond 3G area. He also participated in several European projects such as E2R and MOCCA. Until now, he has published 6 books, around 400 publications in journals and conferences in the area of telecommunications. His main research interests are theory and applications in wireless communication area. He was awarded by government, city of Beijing and Ministry of Information Industry several times for his great contribution to the industry and research activity in China.Hu Zheng is a PH.D candidate in mobile communications engineering in Wireless Technology Innovation Institute (WTI) at Beijing University of Posts and Telecommunications (BUPT). He received B.S degree from Nanjing University of Posts and Telecommunications in 2002, majoring in computer communications engineering. He currently works on serivce aspects of mobile ubiquitous communication system with focus on design and performance evaluation of interaction protocols and services in self-organized service environment.Wang Xu received the B.Tech. degree in electronic engineering from Beijing Polytechnic University (now named as Beijing University of Technology), Beijing, China, in 2002. Now he is working for his Ph.D. degree in Wireless Technology Innovation (WTI) Institute, Beijing University of Posts and Telecommunications (BUPT). His current interests include wireless communications in personal area, ad hoc networks and peer-to-peer system.Li Yinong received the BS degree major in Telecommunication Engineering in 1993 from Beijing University of Posts and Telecommunications, the MS degree and PhD degree major in Telecommunication and Electronic System in 1995 and 2003 from the Beijing University of Posts and Telecommunications. He is currently a lecture of STE (School of Telecommunication Engineering) of BUPT. His main research interests include service modeling, service composition approach, and intelligent service. In BUPT, he has given several lectures to both graduate and undergraduate students such as Information Theory, Speech Recognition, Pattern Recognition and Artificial Intelligence.  相似文献   

14.
Numerous studies have shown that packet reordering is common, especially in networks where there is high degree of parallelism and different link speeds. Reordering of packets decrease the TCP performance of a network, mainly because it leads to overestimation of the congestion in the network. In this paper, we analyse the performance of networks when reordering of packets occur. We propose a proactive solution that could significantly improve the performance of the network when reordering of packets occurs. We report results of our simulation experiments, which support this claim. Our solution is based on enabling the senders to distinguish between dropped packets and reordered packets. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

15.
This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.  相似文献   

16.
The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.  相似文献   

17.
An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.  相似文献   

18.
In general, there are several many devices that can overload the network and reduce performance. Devices can minimize interference and optimize bandwidth usage by using directional antennas and by avoiding overlapping communication ranges. In addition, devices need to carefully manage their use of resources, such as bandwidth and energy. Bandwidth is limited in wireless personal area networks (WPANs), so devices need to carefully select which data to send and receive. In this paper, an intelligent performance analysis of energy-efficient resource optimization model has been proposed for device-to-device (D2D) communication in fifth-generation (5G) WPAN. The proposed energy-efficient resource allocation in D2D communication is important because it helps reduce energy consumption and extend the lifespan of devices that are communicating with each other. By allocating resources in an efficient manner, communication between two devices can be optimized for maximum efficiency. This helps reduce the amount of energy needed to power the communication, as well as the amount of energy needed to power the device that is communicating with another device. Additionally, efficient resource allocation helps reduce the overall cost of communication, as the use of fewer resources results in a lower overall cost. The proposed efficient resource allocation helps reduce the environmental impact of communication, as less energy is used for communication. The proposed energy-efficient resource allocation model (EERAM) has reached 92.97% of energy allocation, 88.72% of power allocation, 87.79% of bandwidth allocation, 87.93% of spectrum allocation, 88.43% of channel allocation, 25.47% of end-to-end delay, 94.33% of network data speed, and 90.99% of network throughput.  相似文献   

19.
米酵菌酸对小鼠肝和心肌细胞毒性作用的超微结构研究   总被引:4,自引:0,他引:4  
目的:观察米酵菌酸对小鼠肝、心肌细胞毒性作用的超微结构改变,探讨米酵菌酸中毒的机理,方法:小鼠腹腔注射不同剂量的米酵菌酸,2h后取其肝和心肌组织,通过电镜观察其细胞超微结构的改变,结果:电镜下可见肝细胞和心肌细胞的线粒肿胀,内嵴断裂,模糊或消失,基质局部或全部空亮,呈囊泡样变,偶见其中含髓样小体,上述线粒体内嵴和膜结构的病变随米酵菌酸剂量的增加而加重,结论:米酵菌酸对小鼠肝、心肌细胞毒性作用以线粒体的损伤较为突出,因此我们认为,线粒体内膜的破坏造成线粒体的功能障碍,影响细胞呼吸,使细胞缺氧导致小鼠中毒死亡。  相似文献   

20.
真空共晶技术的研究应用   总被引:2,自引:2,他引:0  
共晶焊是微电子组装中的一种重要的焊接工艺,在混合集成工艺技术中有着重要的地位.对共晶的概念以及原理进行了介绍,通过比较传统的镊子共晶与真空共晶,对真空共晶工艺的优越性进行了介绍,并分析了真空共晶焊接的工艺原理和工艺过程,对真空共晶的质量影响因素进行了讨论,提出并且论证了提高共晶质量的措施.还针对共晶过程中缺陷的出现原因进行了讨论.通过实验证明了真空共晶的可行性,并且得到了良好的共晶效果.  相似文献   

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