QuRiNet: A wide-area wireless mesh testbed for research and experimental evaluations

Research in wireless mesh networks has been growing in recent years. Many testbeds have been created to study networking protocols in wireless mesh networks. In this work, we describe QuRiNet, an outdoor wide-area wireless mesh network deployed in a natural reserve. QuRiNet comprises of over 30 wireless nodes, spread over 2000 acres of wilderness. QuRiNet provides the backbone infrastructure for transporting ecological and environmental data from the natural reserve to the on-campus laboratories. Mesh nodes in QuRiNet are powered by solar energy, and comprise of multiple radios per node. Physical link distances in QuRiNet range from hundreds to thousands of meters. A parallel goal of deploying QuRiNet is to create a novel platform for advanced research in wireless mesh networks. In this report, we share our experiences in the deployment and maintenance of QuRiNet in its unique setting. We also describe various research efforts that have been leveraging the QuRiNet testbed. Several interesting measurement results are reported, along with the impact of various network configurations and technological variations on the functionality of the testbed. QuRiNet has been used for a variety of experimental studies including: channel assignment, network monitoring, and mobility studies. Current and future study plans include experimental evaluations of various security and reliability research.     

基于改善AMOLED TFT均匀性和稳定性像素补偿电路

有机发光二极管显示器(OLED)正越来越多地用于中小尺寸的显示,但在大尺寸方面进展缓慢,因为在有源大尺寸方面对OLED的稳定性和均匀性要求较高,需要设计像素补偿电路。各研究机构提出了像素补偿电路用于改善OLED的均匀性和稳定性等问题,文中对目前采用有源OLED的α-Si TFT和p-Si TFT的各种像素补偿电路进行了分析。分析结果表明,文中设计方案取得了一定的效果,但尚存不足。     

基于USB 2.0总线的高速红外场景数字注入接口设计

提出了一种基于USB 2.0总线的高速红外场景数字注入接口的实现方案,解决了目标检测研究中真实红外图像、红外测试图像获取问题,可用于信号处理系统的仿真测试和性能评价,并对该方案进行了硬件实现,编写了相应的驱动程序、回放程序.     

A universal matrix solver for integral-equation-based problems

A new method has been developed for compressing the matrices that occur in most integral-equation-based computer programs. This method is easy to interface with existing computer programs, and allows them to run significantly faster and with significantly less memory. This method applies not only to electromagnetic and acoustic computation, but also to most programs involving a Green's function or any integral equation with a kernel having some smoothness properties. Our numerical computations, running on a high-end personal computer, have achieved compression ratios of fifty times, and compressed inversion of the matrices fifty times faster than by previous methods. For larger problems, solved on high-performance computers, these ratios would improve to about one thousand to one for larger moment method problems.     

Adaptive Antennas and Receivers (Weiner, M.M., Ed.; 2005) [Reviews and Abstracts]

This book provides an introduction to recent research and applications of adaptive antennas and receivers. It lays heavy emphasis on methods of dealing with non-homogeneous statistical environments, which are frequently encountered in practice and are not well treated by conventional approaches. A major component of the work reported in this book is based on computer analysis and simulations. Many of the authors have made copies of their programs and algorithm implementations available for the use of the reader. Those programs that care currently available for downloading from the publisher's Web page are described in an appendix at the end of the book. The book also provides extensive references and several appendices. The book's primary value is as a reference for those who are trying to validate, extend, or apply adaptive system technology to real-world conditions.     

Engineering Entrepreneurship: does entrepreneurship have a role in engineering education?

Many engineering programs have recently added courses and material on "engineering entrepreneurship". These programs represent a diverse understanding of what engineering students should receive in the way of instruction in the area of entrepreneurship. This paper examines various definitions of engineering entrepreneurship, and also examines the pedagogical justification for including entrepreneurship in engineering education. The authors use as a context the engineering programs at The University of Texas at Austin, particularly the Department of Mechanical Engineering. The paper examines educational objectives and criteria discussed in documents produced by the National Science Foundation, the American Society of Mechanical Engineering International, the Accreditation Board for Engineering and Technology, and other sources, to develop one approach for entrepreneurship education.     

Engineering education: A perspective and some current problems

Many forces contribute to the rapid changes that have taken place in engineering education; among the current forces are the continuing electronics revolution and the new energy revolution. The most dramatic of the changes since World War II has been the shift from an undergraduate enterprise to one with equal emphasis on graduate study. Of the many problems facing engineering education, it is suggested that special attention be given to the curriculum, to the graduate degrees be given, and to interdisciplinary programs.     

Radar remote sensing of the clear atmosphere—Review and applications

This is a review of clear-air radar with special emphasis on applications. The history of radio scattering from turbulence-induced refractive-index fluctuations is discussed along with current research programs using clear-air radars. Applications involving wind measurement are presently being implemented and the first operational use of clear-air radar will be to improve weather prediction. Eventually, the same clear-air radar system used to observe the weather will be used for optimum routing of aircraft for fuel economy and to estimate transport of pollutants in acid rain studies. Clear-air radar also can potentially be used as an airport hazard monitor for wind shear and wingtip vortices. A new application for clear-air radar is monitoring the presence and height of refractive layers aloft to predict anomalous propagation and estimate unusual radar coverage. Because insects are often detected by clear-air radars, we have included insects as clear-air targets and discuss the use of radar to study insects and birds.     

Ionospheric studies and sounding at the CRIRP

The studies and research which have been carried out for ionospheric sounding at the CRIRP (China Research Institute of Radiowave Propagation) are briefly described. Also described are major results, including the setup and programs of the observation network. Finally, the future, developing plans of the CRIRP are described     

Sensor networks: evolution, opportunities, and challenges

Wireless microsensor networks have been identified as one of the most important technologies for the 21st century. This paper traces the history of research in sensor networks over the past three decades, including two important programs of the Defense Advanced Research Projects Agency (DARPA) spanning this period: the Distributed Sensor Networks (DSN) and the Sensor Information Technology (SensIT) programs. Technology trends that impact the development of sensor networks are reviewed, and new applications such as infrastructure security, habitat monitoring, and traffic control are presented. Technical challenges in sensor network development include network discovery, control and routing, collaborative signal and information processing, tasking and querying, and security. The paper concludes by presenting some recent research results in sensor network algorithms, including localized algorithms and directed diffusion, distributed tracking in wireless ad hoc networks, and distributed classification using local agents.     

Symbolic Polynomial Maximization Over Convex Sets and Its Application to Memory Requirement Estimation

Memory requirement estimation is an important issue in the development of embedded systems, since memory directly influences performance, cost and power consumption. It is therefore crucial to have tools that automatically compute accurate estimates of the memory requirements of programs to better control the development process and avoid some catastrophic execution exceptions. Many important memory issues can be expressed as the problem of maximizing a parametric polynomial defined over a parametric convex domain. Bernstein expansion is a technique that has been used to compute upper bounds on polynomials defined over intervals and parametric “boxes”. In this paper, we propose an extension of this theory to more general parametric convex domains and illustrate its applicability to the resolution of memory issues with several application examples.      

SeSFJava harness: service and assertion checking for protocol implementations

Many formal specification languages and associated tools have been developed for network protocols. Ultimately, formal language specifications have to be compiled into a conventional programming language and this involves manual intervention (even with automated tools). This manual work is often error prone because the programmer is not familiar with the formal language. So our goal is to verify and test the ultimate implementation of a network protocol, rather than an abstract representation of it. We present a framework, called services and systems framework (SeSF), in which implementations and services are defined by programs in conventional languages, and mechanically tested against each other. SeSF is a markup language that can be integrated with any conventional language. We integrate SeSF into Java, resulting in what we call SeSFJava. We present a service-and-assertion checking harness for SeSFJava, called SeSFJava harness, in which distributed SeSFJava programs can be executed, and the execution checked against services and any other correctness assertions. The harness can test the final implementation of a concurrent system. We present an application to a data transfer service and sliding window protocol implementation. SeSFJava and the harness has been used in networking courses to specify and test transmission control protocol-like transport protocols and service.     

近似镜像网页检测算法的研究与评价

当前在WWW上有众多的近似镜像web页面,如何快速准确地发现这些内容上相似的网页已经成为提高搜索引擎服务质量的关键技术之一.为基于关键词匹配的搜索引擎系统提出了5种近似镜像网页检测算法,并利用“天网”系统对这5种算法进行了实际评测.另外还将它们与现有的方法进行了对比分析.本文所论述的近似镜像检测算法已成功地被用于消除“天网”系统的重复网页,同时也可广泛应用于数字化图书馆的搭建.     

GUI-system for computer assisted programming of industrial robots

During the last few years the interest in methods of assisting programming within FMS has been growing. It is the outcome of the development in the Flexible Manufacturing System (FMS) field, especially in the automobile and machine building industries. Industrial robots and CNC-machines are basic elements of FMS (EFMS). The robot work space with the EFMS is called the scene (SC). Many scientists and robot manufacturers started developing the off/on-line computer systems for IR programming some time ago. These programs facilitate the tests of robots programs and the detection of semantic errors in their program and possible collisions with FMS objects before starting the production in FMS. In the Institute of Machine Technology the first stage of the SPMT-R computer off-line programming system for IRb-ASEA industrial robot has been completed, then the development of GUI version of the system began.     

北大重离子所离子注入工作现况

北京大学初步建成能量直至兆电子伏级的离子加速器——离子注入设备系统。本文总结了北大重离子物理所离子束应用组几年来开展离子注入研究的工作,包括:开发应用微机计算离子射程分布的SARIS、TRION、MACA程序,其中后者可适用于高剂量注入动态靶;实验研究了MeV硼离子注入硅的分布,提出了多能注入形成平台载流子分布的实用方法;在离子注入高分子材料研究中观测到了增强氧化和C=C双键形成等现象,研究了光刻胶的离子束曝光特性;系统研究了应用离子束混熔技术在低碳钢表面形成的Al和Al合金镀层,大大提高了基体钢的耐腐蚀能力。     

面向对象软件的回归测试策略研究

面向对象软件测试已成为软件工程领域的一个重要研究课题.目前已提出的回归测试策略大都是针对结构化程序的,对面向对象软件的回归测试策略研究得很少.文章在分析面向对象程序设计语言对软件测试影响的基础上,讨论了面向对象软件测试的测试策略,重点研究了基于类的回归测试策略.     

飞秒激光与晶体和玻璃的相互作用

总结了飞秒激光与晶体和玻璃相互作用产生的新现象,如光致折射率改变、光致晶体相变、光还原稀土离子及光致发光等.并分析了它们可能的应用.同时简要的介绍了各种现象产生的机理,展望了飞秒激光与其它物质相互作用可能的研究方向及可能出现的新现象.指出了进行这些研究时可能采用的新方法.     

Managing end‐to‐end quality of service in multiple heterogeneous wireless networks

Supporting quality of service (QoS) in wireless networks has been a very rich and interesting area of research. Many significant advances have been made in supporting QoS in single wireless networks. However, the support for QoS across multiple heterogeneous wireless networks will be required in future wireless networks. In connections spanning multiple wireless networks, end‐to‐end QoS will depend on several factors such as mobility patterns, connection patterns, and the QoS policies in each of the networks. In this paper, we present an architecture for multiple heterogeneous wireless networks, several QoS schemes, a simulation model and several interesting results. The simulation model can evaluate the QoS performance under a variety of network configurations, user and mobility types, and network resources. Our results show that end‐to‐end QoS depends on several factors, including system utilization, mobility levels, and the individual QoS schemes implemented in individual networks. We also show how the QoS ideas presented in this paper can be used by wireless carriers for improved QoS support and management. Copyright © 2006 John Wiley & Sons, Ltd.