多核浮点非线性运算协处理器的设计与实现

在载人航天飞船的终端仪器仪表设计中,处理算法中的浮点非线性运算常采用库函数实现,但软件实现非线性函数执行速度慢,限制了浮点算法的应用。为此,针对航天领域处理器不支持非线性函数运算的情况以及浮点算法执行速度慢的问题,提出一种多核并行执行浮点非线性运算处理方法,利用现场可编程门阵列内部并行架构带来的低延迟特性来提高非线性浮点运算的速度。仿真实验结果表明,该方法可计算有限定义域范围内的浮点非线性函数,有效提高浮点运算的执行速度。     

一种微电阻率成像测井仪数字相敏检波新算法

针对微电阻率成像测井仪井下稳定、高效及低功耗设计要求,提出了一种较新颖的数字相敏检波实现算法,主要包括数据的分相累加、公因式乘法、匹配加法以及反正切与平方根运算等.其中,分相累加算法在采集模块FPGA中完成,公因式乘法和匹配加法在处理模块FPGA中完成,反正切和平方根运算在处理模块DSP中完成.通过此种相敏检波算法实现方式,能有效降低系统功耗,并实现地层阻抗的准确测量.     

基于FPGA误差可控的浮点运算加速器研究

浮点运算是高性能计算(HPC)领域的基础运算。在大数据与云计算的背景下,高性能计算平台需要处理的数据量与日俱增,而且浮点数的舍入误差在大规模、长时程的运算中会产生累积,因此,在提升浮点运算性能的同时保证计算结果的可靠性非常重要。利用现场可编程门阵列(FPGA)可编程、低功耗、灵活性强的特点,针对含复杂单项运算的浮点多项式设计一种浮点运算加速器。基于无误差变换的思想,通过计算得出舍入误差值,将其补偿到浮点数值上,从而实现误差可控。采用异步并行的方式实现运算加速,并通过构建CPU-FPGA平台最大化地利用计算资源,保证计算任务执行的高效性。数据测试结果表明:在不限制对称性下的数值相对论模拟运算中,该加速器在200 MHz的主频下可达到91.85 MFLOPs的峰值性能;与Intel i7 6700K CPU运行最大线程数的性能相比,该加速器实现了50.54的加速比,并在该条件下获得了平均53.6%的精确结果百分比以及更低的相对误差,表明其具备较高的可靠性。     

定点DSP C55X实现浮点相关运算

引言 DSP结构可以分为定点和浮点型两种.其中,定点型DSP可以实现整数、小数和特定的指数运算,它具有运算速度快、占用资源少、成本低等特点;灵活地使用定点型DSP进行浮点运算能够提高运算的效率.目前对定点DSP结构支持下的浮点需求也在不断增长,主要原因是: 实现算法的代码往往是采用C/C 编写,如果其中有标准型的浮点数据处理,又必须采用定点DSP器件,那么就需要将浮点算法转换成定点格式进行运算.同时,定点DSP结构下的浮点运算有很强的可行性,因为C语言和汇编语言分别具有可移植性强和运算效率高的特点,因此在定点DSP中结合C语言和汇编语言的混合编程技术将大大提高编程的灵活度,以及运算速度.     

基于RISC-V浮点指令集FPU的研究与设计

针对目前浮点运算软件实现速度慢,不能满足嵌入式处理器实时性要求以及运算种类有限等问题,提出了一种基于RISC-V指令集的浮点处理器,能够执行加法、减法、乘法、除法、平方根、乘累加以及比较运算,完全符合IEEE 754-2008标准。在VCS仿真环境下对浮点处理器进行了功能验证,各模块均能满足正确性要求。将浮点处理器与一款开源处理器核蜂鸟E203集成,使用SMIC 0.18工艺库完成了逻辑综合,并在FPGA上对设计进行了测试。结果表明,该浮点处理器的逻辑门数仅为24 200,吞吐量为150 MFLOPS,与已公开文献的设计方案相比,硬件面积分别减少7%、1.5%。综合运行频率可达100 MHz。     

支持超越函数的浮点运算单元的设计与实现

介绍自主设计的龙腾C2微处理器中浮点运算单元的设计与实现.该处理器与Intel 80486DX4指令系统兼容,支持IEEE 754标准扩展精度的浮点基本函数和超越函数运算.介绍了浮点运算单元的结构,分析了实现超越函数的高精度CORDIC算法的流程,讨论了实现浮点超越函数运算的数据通路和控制通路结构,并给出了仿真结果和精度评估结果.仿真和分析的结果表明,浮点运算单元的设计满足龙腾C2微处理器的设计要求.     

一种高性能四倍精度浮点乘加器的设计与实现

高精度、高性能浮点运算部件是高性能微处理器设计的重要部分。通过对传统双精度浮点乘加运算算法的研究,结合四倍精度浮点数据格式特点,设计并实现一种高性能的四倍精度浮点乘加器(QPFMA),该乘加器支持多种浮点运算,运算延迟为7拍,全流水结构。采用双路加法器改进算法结构,优化头零预测和规格化移位逻辑,减小运算延迟和硬件开销。通过参数化设计验证方法,实现高效的正确性验证。逻辑综合结果表明,基于65 nm工艺,该QPFMA频率可达1.2 GHz,比现有的QPFMA设计运算延迟减少3拍,频率提高约11.63%。     

可重构浮点混合/连续乘-加器的设计与实现

浮点连续乘-加、混合乘-加和三操作数加等浮点算术运算在科学计算领域中应用越来越频繁,为设计一款支持浮点连续乘-加、混合乘-加和三操作数加的多功能浮点运算单元,提出一种可重构浮点混合/连续乘-加器,通过对控制位的配置可以实现多种浮点数据操作。该乘-加器采用8级流水线,可以实现单周期的浮点乘累加,大幅提高数据处理吞吐量,同时支持三操作数加和两操作数和的累加。在Modelsim SE6.6f中对该设计进行仿真验证,结果表明其能够在Xilinx Virtex-6 FPGA上实现,资源消耗2 631个LUT,频率可达250 MHz,结果证明该浮点混合/连续乘-加器具有较大的使用价值。     

处理器中的浮点除法和平方根运算算法

硬件设计中发展了许多除法运算算法,各算法在商收敛性速度、基本硬件单元和数学公式等许多方面均不相同。通过对现在较流行的浮点除法和平方根运算算法进行介绍,分析各浮点除法和平方根运算算法的思路和适合的不同场合,比较各自的优缺点。举例说明LSFT32处理器中浮点除法算法的选择。只有当算法的思路及其特点与运算器的结构相匹配时才能充分发挥速度和规模的优势,所选用的算法才是有意义的。     

处理器中的浮点除法和平方根运算算法

硬件设计中发展了许多除法运算算法，各算法在商收敛性速度、基本硬件单元和数学公式等许多方面均不相同。通过对现在较流行的浮点除法和平方根运算算法进行介绍，分析各浮点除法和平方根运算算法的思路和适合的不同场合，比较各自的优缺点。举例说明LSFT32处理器中浮点除法算法的选择。只有当算法的思路及其特点与运算器的结构相匹配时才能充分发挥速度和规模的优势，所选用的算法才是有意义的。     

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。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.