一种新的Turbo乘积码简化迭代译码算法

针对二维TPC码提出一种新的简化迭代译码算法以及一种新的译码器迭代结构。该算法在Chase迭代软输入软输出译码的基础上,通过简化软输入信息和外信息的计算来降低译码复杂度和系统存储量。仿真结果验证了该算法的正确性和可行性。     

低复杂度的Turbo乘积码迭代译码研究

Turbo乘积码（简称TPC码）的传统迭代译码算法寻找竞争码字难、软信息存储量大。针对这些问题提出一种低复杂度的迭代译码算法,并得出新的译码器迭代结构。该算法在Chase迭代SISO译码的基础上,采用无需寻找竞争码字的相关运算来简化软输出信息的计算,同时用前一个迭代译码单元的软输入信息替换传统算法中信道原始接收信息,然后与当前迭代译码单元的软输出信息直接进行线性叠加后作为下一个迭代译码单元的软输入,从而简化了软输入信息的计算和系统存储量。仿真结果验证了该算法的可行性和有效性。     

基于DMR通信协议的信道编解码研究

为了提高DMR系统基带算法的性能,分析研究了DMR通信协议中的BPTC码和变长BPTC码.针对这两种码,提出了利用和积算法作为软输入软输出译码器,进行迭代译码的新方案.该方案在MATLAB下进行了仿真,并与伴随式译码方案进行了对比分析.BPTC和变长BPTC码的仿真实验结果表明,采用软判决迭代译码的方案在低信噪比和高信噪比时都有更好的编码增益.     

三维TPC编解码器的仿真研究

对三维TPC（Turbo乘积码）编译码的算法及性能进行了仿真。TPC编码的3个子码都采用（16,11）的扩展汉明码,编码码率约为0．32,码字长度为4096。三维TPC译码采用基于Chase2算法的软输入／软输出迭代译码算法。利用matlab进行仿真,采用4次迭代,在AWGN信道中,Eb／N0为3dB时,误码率小于1×10^-6。这种纠错方式适用于带宽宽,功率受限且传榆性能要求高的通信系统中。     

TPC自适应迭代译码方法

提出一种TPC自适应迭代译码算法。从接收到的软信息估算信道的信噪比;根据信噪比选择最优的软译码迭代因子,将迭代因子与软信息送入SISO迭代译码器;检测每次SISO译码器的输出,达到迭代终止条件即结束译码。提出的自适应迭代译码方法大大地增强了译码器的灵活性,动态的选择译码策略,尤其在低噪声信道下有效地降低了译码的功耗。     

高斯白噪声信道下Turbo乘积码应用仿真

本文介绍了一种新型的前向纠错编码方案--Turbo乘积码(TPC).分析了Turbo乘积码的编译码原理.并对高斯白噪声信道下的TPC编译码性能进行了仿真.通过选取不同参数子码组合的性能对比,提出了最优的TPC编译码方案.仿真结果显示,与传统的卷积码和Turbo码相比,Turbo乘积码不仅具有优异的误码率性能,而且可以做到更高的编码效率.     

TPC码译码器硬件仿真的优化设计

介绍一种TPC码迭代译码器的硬件设计方案,基于软判决译码规则,采用完全并行规整的译码结构,使用VHDL硬件描述语言,实现了码率为1/2的(8,4)二维乘积码迭代译码器,并特别通过硬件测试激励来实时测量所设计迭代译码器的误码率情况,提出了优化设计方案,和传统的硬件仿真方法相比大大提高了仿真效率。仿真结果证明该译码器有很大的实用性和灵活性。     

Turbo码的迭代译码方法的优化设计

迭代译码可以提高Turbo码的译码性能,但也是增加译码复杂性、延时及功率损耗的主要原因。在分析Turbo码的迭代译码原理和译码算法的基础上,提出了一种迭代译码的优化设计方法(Turbo-CRC),即利用循环冗余检测码CRC对Turbo译码器硬判决的输出结果进行检测,可以有效地减小平均迭代次数。计算机仿真结果表明在不降低译码性能和不增加系统复杂度的情况下,使用该方法可以有效地减小平均迭代次数和译码延时,尤其是在大信噪比时,效果更好。     

基于外信息绝对值信噪比的迭代停止准则

针对Turbo码译码延时较大的问题进行研究。通过分析译码器输出外信息绝对值信噪比的统计特性,利用译码器输出外信息绝对值信噪比的收敛特性,提出一种新的迭代停止准则,简称为SBAE准则。将新准则与现有的经典迭代停止准则对比,新准则节省了大量存储空间,通过仿真分析新准则下Turbo性能及平均迭代次数,得出结论:新准则在保证译码性能的同时,有效减少了译码的平均迭代次数,加速了Turbo码的译码过程,提高了译码效率,为Turbo码在实时系统中的应用提供一种有效方法。     

一种改进的Turbo codes译码方法

Turbo码是一种目前研究比较多的纠错码,译码端采用了基于软判决信息输入/输出的反馈迭代结构,译码的迭代是其具有优越纠错性能的关键,也是造成其时延的问题所在,该文提出一种自适应选择迭代次数的方法,实验表明该方法能够在译码结果收敛时自动停止迭代,避免大量无谓的计算,同时保证译码的准确性。     

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。     

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.     

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.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.