数据链抗干扰性能分析

美军联合战术信息分发系统(JTIDS)采用扩频、MSK调制和跳频的组合调制体制以及RS编码、交织多层纠检错编码体系,使系统具有很强的抗干扰性能.以JTIDS为背景,研究数据链通信系统的结构以及采用的抗干扰体制,分析该系统在不同信道环境和人为干扰方式下的符号误码率,并运用SIMULINK通信仿真平台对该系统在高斯白噪声及部分频带干扰情况下的抗干扰性能进行了仿真,对仿真结果进行了分析.     

Link-16数据链抗干扰性能分析与仿真

在部队通信服务问题的研究中,数据链仿真是数据链武器装备论证的重要研究内容和方法,对军队数据链建设具有重要意义.以美军现役战术数据链Link-16为背景,比较分析了数据链系统的四类信息传输方式,为提高抗干扰性能,介绍了主要的抗干扰技术.利用Simulink软件对数据链系统建立了链路仿真平台,重点构建了直序扩频模块和跳频模块,对在加性高斯白噪声和莱斯衰落影响下的信号传输进行了仿真并进行了抗干扰性能分析.通过仿真与分析可以看出,RS编码、直序扩频、跳频等技术保证了Link-16数据链的高抗干扰性能,使其满足军用通信要求.     

DS-BPSK方案下的UWB非相干接收方法

分析了采用DS-BPSK调制方式的UWB通信系统非相干接收方案,并研究了一种以差分能量检测非相干接收方式为基础的非相干接收处理算法,在此基础上进行了非相干接收方式下DS-BPSK UWB系统的性能分析,并利用Matlab进行了仿真.仿真结果表明:本文所讨论的非相干接收算法对同步误差不敏感,可以很好地适用于不能精确同步的通信场合.     

自适应跳频技术在提高数据链抗干扰性能中的应用

跳频技术是扩频通信中的一种抗干扰的实用技术。自适应跳频技术是建立在自动信道质量分析基础上的一种技术,该技术能使跳频通信过程自动避开被干扰的跳频频率点,并以最小的发射功率、最低的被截获概率,达到在无干扰的跳频信道上长时间保持优质的通信。本文介绍这种自适应跳频通信基本原理和关键技术以及在提高数据链抗干扰性能中的应用,并通过计算机仿真论证了其优越性能。     

JTIDS系统仿真与性能分析

JTIDS是美国C^3I系统的重要组成部分,具有很强的抗随机噪声和人为干扰的能力。我周边地区已装配该系统,故研究该系统的性能以及干扰方式迫在眉睫。该文简要说明了JTIDS的工作方式,从JTIDS系统的数据模型人手,完成了包括RS编码、交织编码、软扩频、MSK调制、跳频、跳时在内的整个JTIDS系统仿真。通过蒙特卡罗仿真分别得到了该系统在不同噪声环境下的误码率图,为进一步研究和干扰JTIDS系统提供了依据和数据源。     

移动网络通信节点抗干扰方法的研究与仿真

研究移动网络抗干扰性能.目前移动通信系统均采用小区制结构,以同频复用方式来提高频率利用率,每隔一定的距离,小区可重复使用同一频率.随着小区分裂,同频复用系数增加时,当同频干扰的增加时,会直接影响到通信质量.提出了移动网络节点属性自学习的抗干扰方法,及时获取节点的状态并调整不同类别的参数,对节点的由于干扰造成的时变动态性进行准确分析,构建动态推理区域,不同节点采用Gossip传输自身的采样信息,解决同频干扰问题.仿真结果表明,上述方法可改进抗干扰性能,解决了节点随机性特征产生的干扰.     

一种新型无人机数据链抗压制干扰技术的研究

从提高无人机数据链的抗干扰性能出发,在研究跳频扩频(FHSS)、跳频正交频分复用(FH-OFDM)基础上,结合正交码时分多子信道扩谱调制(OC-TDMSCSSM)提出了一种单一正交码跳频正交频分复用(SOCFH-OFDM)新的抗干扰方案,建立了数学模型,推导了抗干扰性能误码率公式.仿真结果表明,在莱斯信道下,当误码率达到10-5时,系统的抗宽带干扰和抗窄带干扰性能均比OC-TDMSC-SSM系统要高出1.5 dB左右.     

跳频通信系统抗干扰性能仿真研究

跳频通信系统与常规定频通信系统相比具有较强的抗干扰能力。文中在介绍跳频通信基本原理的基础上,分析了在宽带阻塞干扰和部分频带干扰这两种常见干扰下的跳频通信系统的抗干扰性能,并借助计算机仿真工具MATLAB/Simulink搭建仿真模型,得到了在两种干扰下的误码率-信噪比曲线,从而验证了理论分析的结果。     

跳频通信系统抗干扰性能仿真研究

跳频通信系统与常规定频通信系统相比具有较强的抗干扰能力。文中在介绍跳频通信基本原理的基础上，分析了在宽带阻塞干扰和部分频带干扰这两种常见干扰下的跳频通信系统的抗干扰性能，并借助计算机仿真工具MATLAB／Simulink搭建仿真模型，得到了在两种干扰下的误码率-信噪比曲线，从而验证了理论分析的结果。     

JTIDS信号的高效信道化接收及检测方法

根据联合战术信息分发系统（Joint Tactical Information Distribution System,JTIDS）信号的特点,提出一种基于多相滤波的JTIDS信号接收方法。该接收模型具有全概率接收JTIDS信号的特点,而且所需计算复杂度低。在信号接收后,通过能量检测对输出信号进行脉冲宽度检测,判断信号是否为JTIDS信号。仿真结果表明该方法在信噪比为正时具有较好的性能。     

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.     

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.     

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     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

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。