基于信号可信度的压缩感知协作频谱检测算法

压缩感知为认知无线电的宽频谱感知提供了一种新的方法和思路。基于压缩感知的原理,提出了一种多认知用户协作场景下,基于信号可信度的协作频谱检测算法。该算法根据不同认知用户接收信号的优劣判定用户感知结果的可信度,并利用正交匹配协作追踪算法获得认知区域内的频谱占用情况。仿真结果表明,该算法在不同信噪比范围下其检测性能均优于传统算法,以较小的复杂度代价改善了检测性能。     

基于动态阈值的可信度加权协作频谱感知

为了提升受阴影衰落等因素影响下的协作频谱感知性能, 采取了一种改进的基于动态阈值和可信度相结合的协作频谱感知方法。该方法利用各认知用户的检测信噪比对检测可信度较低的认知用户进行过滤, 各认知用户根据检测信噪比设定一个适合自身的动态阈值进行能量感知, 融合中心结合各单节点感知结果和分配的传输可信度作出最终判决。仿真结果表明, 在检测信道和传输信道均受到阴影衰落等因素严重影响下, 与单纯的动态阈值协作感知和传统的可信任度协作感知方法相比, 该方法能获得较高的检测概率。     

基于噪声不确定性的双门限协作频谱感知算法

传统的双门限协作频谱感知算法忽略了两门限之间认知用户的本地感知信息,而利用这部分信息可以进一步提高认知无线电系统的感知性能。为此,在等增益合并的基础上,提出一种顺序自适应分步合并算法。两门限之间的认知用户根据接收信噪比分步上传本地感知信息,融合中心自适应地调整参与协作的认知用户数,以减小系统的上传数据开销。推导在Rayleigh衰落信道条件下,认知用户上传数据的平均比特数以及全局检测概率的闭式表达式。理论分析和仿真结果表明,该算法能以较小的数据开销获得较优的协作感知性能。     

基于BP神经网络的协作频谱感知技术

认知无线电技术可以利用主用户未使用的频谱资源来有效地提高频谱利用率。单用户感知技术虽然简单但可靠性较低,协作频谱感知技术可以显著地提高频谱感知的性能。现有的大部分协作感知都是在假设各认知用户的信噪比相同的前提下进行研究。然而在实际环境中,由于每个认知用户所处的环境不同,其信噪比不同,对融合中心判决的影响也不同。如何在提升检测性能的同时提升系统的能量效率是关键问题。提出一种基于BP(Back Propagation)神经网络的协作频谱感知技术,它利用频谱环境的历史信息,通过BP神经网络提高频谱感知性能。仿真结果表明,该算法可以在保证协作感知性能的同时减少参与协作的认知用户数,从而减少能量消耗。     

基于Agent的协作频谱感知算法

为了提高认知无线电频谱感知技术的性能, 提出一种新的基于Agent的协作频谱感知算法。该算法在本地检测中使用多门限能量检测,同时将认知节点估计的信噪比的值发送到Agent控制中心,在控制中心根据每一个认知节点发送的信噪比的值和该节点与发射机的距离进行权衡,选取可靠性和有效性较高的认知节点参与判决融合。仿真结果表明,该算法能够很好地提高认知无线电网络的协作频谱感知能力,同时在一定程度上减少了原有协作感知算法中参与感知节点的数目。     

基于信任度加权的合作频谱感知算法

为进一步提高认知无线电频谱感知性能,提出一种基于信任度加权的软合并感知算法TWCS(trustweighted cooperation sensing)。该算法首先定义一个模糊型指数信任度函数,对两认知用户间的信任程度进行量化处理,并通过信任度矩阵度量各认知用户测得数据的综合信任程度,以合理分配测得数据在融合过程中所占权重。仿真结果表明,与最大比合并和信噪比加权合并等算法相比,TWCS算法不仅具有更强的可靠性,而且使系统整体感知性能得到了较大提高。     

认知无线电网络中基于信任度的频谱感知技术

提出了一种在认知无线网络控制信道带宽受限条件下基于信任度的双门限协同频谱感知算法。首先每个认知用户基于双检测门限独立进行频谱感知,但只有部分可靠的认知用户通过控制信道向认知无线网络基站发送本地感知结果。当所有的用户都不可靠时,选取信任度最高的认知用户发送本地感知结果进行判决。理论分析和仿真表明,同常规能量检测算法相比较,该算法能够在控制信道带宽受限条件下,以较少的网络开销获得更好的频谱感知性能。     

基于权值自适应优化的协作频谱认知算法

提出一种基于权值自适应优化的协作频谱认知算法。根据各协作认知节点的信噪比分配合适的权值向量,反映对检测统计量的贡献大小。基于最小均方误差原则,权值向量可根据实际的各节点信噪比向量进行自适应优化,从而提高认知网络中存在低信噪比节点时的检测性能。仿真结果表明,与传统协作算法相比,该算法无论在节点高信噪比或低信噪比条件下均有更优的检测性能,且收敛速度较快。     

认知无线电网络多用户智能协作频谱感知算法

认知无线电网络中,单用户频谱感知容易受到阴影效应、多径衰落及隐蔽终端等不利因素的影响,造成感知结果的误判.为了提高系统的检测性能,并减少感知花销,提出了多用户智能协作频谱感知算法.各个认知用户根据估计信噪比自适应选择不同的感知策略,当估计信噪比高于选择阈值时采用双门限能量感知,低于选择阈值时则采用循环平稳特征检测,并在同一个感知周期内只进行一种较优的感知策略,从而在不明显增加计算复杂度的情况下,克服了能量感知在低信噪比条件下鲁棒性差的缺点,实现了智能检测.仿真结果表明,智能协作频谱感知有效提高了系统检测概率,缩短了平均感知时间,有较好的鲁棒性.     

基于多融合准则的双门限协作频谱感知算法

认知无线网络中,现有协作频谱感知技术未考虑根据感知用户的可靠性程度,对其判决结果采用不同的融合策略。针对上述问题,提出了一种新的基于多融合准则的双门限协作频谱感知算法。该算法以双门限协作检测为基础,根据感知用户判决结果的可靠程度不同,采用AND准则和OR准则相结合的判决方法,对参与感知的用户判决结果进行分类融合。理论分析和仿真结果表明,该算法与协作频谱感知算法相比,能够显著改善认知无线网络的频谱感知性能。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

基于QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

基于AD9626的模拟信号采集存储卡设计

自然界的绝大部分信号都是以模拟的形式存在,因此模拟信号的采集转换存储在数字时代十分关键。文章讨论了在雷达信号处理领域基于AD9626的AD采集存储卡的设计原理、硬件结构和程序设计与芯片配置等问题,为今后相关领域的研究提供了可参考的方案。     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

A human-computer interface for non-computer specialists

The COM teleconferencing system was designed to be easy to use for both beginners and people with much computer experience. A number of design choices in organizing the human-computer interface were considered very carefully. These design problems are not unique for teleconferencing applications, but will appear in many other developments of human-computer interfaces for non-computer specialists. This report discusses naming conventions, menu format, user commands, help facility and the treatment of ‘type ahead’ from the users.