一种新颖的软件可控Cache优化方法

由于Cache污染问题,传统的仅由硬件控制的Cache替换策略不能得到令人满意的Cache利用率。随着软件可控Cache机制的出现,编译器开始可以直接控制Cache替换,改善Cache行为。本文证明了一个Cache提示优化定理,并依该定理提出了一个由编译器辅助控制的Cache替换策略:最优Cache划分(OCP)。OCPCache替换策略简化了Cache行为和Cache失效分析方法。实验结果表明OCPCache替换策略能有效地降低Cache失效率。     

基于SRAM和STT-RAM的混合指令Cache设计

随着工艺尺寸减小,传统基于SRAM的片上Cache的漏电流功耗成指数增长,阻碍了片上Cache容量的增加。基于牺牲者Cache的原理,利用SRAM写速度快,STT-RAM的非易失性、高密度、极低漏电流功耗等特性设计了一种基于SRAM和STT-RAM的混合型指令Cache。通过实验证明,该混合型指令Cache与传统基于SRAM的指令Cache相比,在不增加指令Cache面积的情况下,增加了指令Cache容量,并显著提高了指令Cache的命中率。     

CMP中基于目录的协作Cache设计方案

片上多处理器中二级Cache的设计和管理是影响其性能的关键因素之一。在私有二级Cache的基础上,提出一种基于集中式一致性目录的协作Cache设计方案,通过有效地管理片上存储资源来优化处理器的性能,从而使该协作Cache具有平均访存延迟小、Cache缺失率低、可扩展性好等优点。实验结果显示,与共享二级Cache设计相比,协作Cache可以将4核处理器的吞吐量平均提高13.5%,而其硬件开销约为8.1%。     

片上多核Cache资源管理机制研究

随着片上多核成为处理器发展的主流和片上Cache资源的持续增长,Cache资源的管理已成为片上多核的关键问题。介绍了片上多核Cache资源管理的研究进展,依据研究内容将Cache资源的管理分为Cache划分和Cache共享两类。对Cache划分,探讨了其主要组成部分和一般形式,分析和比较了典型的片上多核Cache划分机制。对Cache共享,给出了其主要研究内容,并介绍和比较了几种主流的片上多核Cache共享机制。通过分析,认为软硬件协同管理的页划分应是未来片上多核Cache划分机制的研究重点;而片上多核Cache共享机制的研究则应从目标应用的Cache行为特征着手。     

一个由编译器控制的Cache替换策略

由于Cache拓染问题，传统的仅由硬件控制的Cache替换箫略不能得到令人满意的Cache利用率。为解决该问题，EPIC引入了Cache提示以辅助控制Cache替换。文章提出了一个由编译器辅助挖制的Cache替换策略：最优Cache划分（OCP）。OCP Cache替换策略简化了Cache行为和Cache失效分析方法。实验结果表明，OCP Cache替换箫略能有效地降低Cache失效率。     

面向WCET估计的Cache分析研究综述

实时系统时间分析的首要任务是估计程序的最坏情况执行时间(worst-case execution time,简称WCET).程序的WCET 通常受到硬件体系结构的影响,Cache则是其中最为突出的因素之一.对面向WCET计算的Cache分析研究进行了综述,介绍了经典Cache分析框架与Cache分析核心技术,并从循环结构分析、数据Cache分析、多级Cache分析、多核共享Cache分析、非LRU替换策略分析等角度介绍了Cache分析在不同维度上的研究问题与主要挑战,总结了现有技术的优缺点,展望了Cache分析研究的未来发展方向.     

多核处理机系统Cache管理技术研究现状

多核处理器的Cache结构设计和管理是微处理器设计领域的重要问题。当前主流的商用微处理器均采用共享最后一级Cache的系统结构,而片上最后一级Cache的性能通常对处理器的性能影响较大,因此共享Cache的管理问题成为当前研究热点。本文首先介绍当前主流多核处理器及其设计问题,然后介绍了共享Cache管理的三项重要技术:线程调度、NUCA和Cache划分,最后给出多核处理器Cache管理技术的发展方向。     

Cache结构的低功耗可重构技术研究

在分析Cache性能的基础上介绍了当前低功耗Cache的设计方法,提出了一种可重构Cache模型和动态可重构算法。Cache模型能够在程序运行过程中改变相联度和大小,动态可重构算法能够在运行时针对不同的应用程序对可重构Cache进行配置。通过对Cache的动态配置,不仅可以提高Cache命中率,还能够有效降低处理器的功耗。     

一种嵌入式系统的滑动Cache机制设计

为了提高嵌入式系统中Cache的使用效率,针对不同类型的应用程序对指令和数据Cache的容量实时需求不同,提出一种滑动Cache组织方案.均衡考虑指令和数据Cache需求,动态地调整一级Cache的容量和配置.采用滑动Cache结构,不但降低了一级Cache的动态和静态泄漏功耗,而且还降低了整个处理器的动态功耗.模拟仿真结果表明,该方案在有效降低Cache功耗的同时能够提高Cache的综合性能.     

多核处理器可重构Cache功耗计算方法的研究

多核动态可重构Cache是解决Cache功耗困扰的一个重要方法。现有Cache功耗模拟器并不能很好地支持多核动态可重构Cache功耗研究,通过对多核动态可重构Cache的功耗模型进行研究,找到了计算可重构Cache的方法和思路,应用CACTI来分别构建各个组成结构的Cache功耗模型,以较为准确地测算可重构Cache的功耗。在Simics模拟器下构建动态可重构Cache,运行测试程序,对比传统的体系结构,可重构Cache的功耗能够得到10.4%的降低。同时,实验中发现功耗的降低不仅仅是动态可重构Cache贡献的,而是由系统综合产生的,因此在低功耗设计中,要综合考虑整体系统的功耗和性能,避免片面地考虑Cache结构而导致整体功耗的提高。     

Modeling of electromagnetic fields in rectangular waveguides by coupled finite–infinite elements

The paper describes the 3D infinite element for modeling of stationary harmonic electromagnetic fields in waveguides. The proposed approximation is a straightforward modification of the analogous approach developed for analysis of scattering problems in unbounded 2D and 3D domains [Comp. Meth. Appl. Mech. Engrg. 188 (2000) 625; Int. J. Num. Meth. Engrg. 57 (2003) 899]. Exponential shape functions in the longitudinal direction are used similarly as in [Comp. Meth. Appl. Mech. Engrg. 140 (1997) 221]. However, arbitrary order of approximation in the tangential direction may be selected due to compatibility with the hp-adaptive edge FE element discretization for Maxwell’s equations in bounded domains reported in [Comp. Meth. Appl. Mech. Engrg. 152 (1998) 103; Int. J. Num. Meth. Engrg. 53 (2002) 147; Comp. Meth. Appl. Mech. Engrg. 169 (1999) 331].     

Node-pancyclicity and edge-pancyclicity of hypercube variants

Twisted cubes, crossed cubes, Möbius cubes, and locally twisted cubes are some of the widely studied hypercube variants. The 4-pancyclicity of twisted cubes, crossed cubes, Möbius cubes, locally twisted cubes and the 4-edge-pancyclicity of twisted cubes, crossed cubes, Möbius cubes are proven in [C.P. Chang, J.N. Wang, L.H. Hsu, Topological properties of twisted cube, Inform. Sci. 113 (1999) 147-167; C.P. Chang, T.Y. Sung, L.H. Hsu, Edge congestion and topological properties of crossed cubes, IEEE Trans. Parall. Distr. 11 (1) (2000) 64-80; J. Fan, Hamilton-connectivity and cycle embedding of the Möbius cubes, Inform. Process. Lett. 82 (2002) 113-117; X. Yang, G.M. Megson, D.J. Evans, Locally twisted cubes are 4-pancyclic, Appl. Math. Lett. 17 (2004) 919-925; J. Fan, N. Yu, X. Jia, X. Lin, Embedding of cycles in twisted cubes with edge-pancyclic, Algorithmica, submitted for publication; J. Fan, X. Lin, X. Jia, Node-pancyclic and edge-pancyclic of crossed cubes, Inform. Process. Lett. 93 (2005) 133-138; M. Xu, J.M. Xu, Edge-pancyclicity of Möbius cubes, Inform. Process. Lett. 96 (2005) 136-140], respectively. It should be noted that 4-edge-pancyclicity implies 4-node-pancyclicity which further implies 4-pancyclicity. In this paper, we outline an approach to prove the 4-edge-pancyclicity of some hypercube variants and we prove in particular that Möbius cubes and locally twisted cubes are 4-edge-pancyclic.     

On local convergence of a Newton-type method in Banach space

In this study we are concerned with the local convergence of a Newton-type method introduced by us [I.K. Argyros and D. Chen, On the midpoint iterative method for solving nonlinear equations in Banach spaces, Appl. Math. Lett. 5 (1992), pp. 7–9.] for approximating a solution of a nonlinear equation in a Banach space setting. This method has also been studied by Homeier [H.H.H. Homeier, A modified Newton method for rootfinding with cubic convergence, J. Comput. Appl. Math. 157 (2003), pp. 227–230.] and Özban [A.Y. Özban, Some new variants of Newton's method, Appl. Math. Lett. 17 (2004), pp. 677–682.] in real or complex space. The benefits of using this method over other methods using the same information have been explained in [I.K. Argyros, Computational theory of iterative methods, in Studies in Computational Mathematics, Vol. 15, C.K. Chui and L. Wuytack, eds., Elsevier Science Inc., New York, USA, 2007.; I.K. Argyros and D. Chen, On the midpoint iterative method for solving nonlinear equations in Banach spaces, Appl. Math. Lett. 5 (1992), pp. 7–9.; H.H.H. Homeier, A modified Newton method for rootfinding with cubic convergence, J. Comput. Appl. Math. 157 (2003), pp. 227–230.; A.Y. Özban, Some new variants of Newton's method, Appl. Math. Lett. 17 (2004), pp. 677–682.]. Here, we give the convergence radii for this method under a type of weak Lipschitz conditions proven to be fruitful by Wang in the case of Newton's method [X. Wang, Convergence of Newton's method and inverse function in Banach space, Math. Comput. 68 (1999), pp. 169–186 and X. Wang, Convergence of Newton's method and uniqueness of the solution of equations in Banach space, IMA J. Numer. Anal. 20 (2000), pp. 123–134.]. Numerical examples are also provided.     

An improved convergence analysis for the Newton–Kantorovich method using recurrence relations

We generate a sequence using the Newton–Kantorovich method in order to approximate a locally unique solution of an operator equation on a Banach space under Hölder continuity conditions. Using recurrence relations, Hölder as well as centre-Hölder continuity assumptions on the operator involved, we provide a semilocal convergence analysis with the following advantages over the elegant work by Hernánde? in (The Newton method for operators with Hölder continuous first derivative, J. Optim. Theory Appl. 109(3) (2001), pp. 631–648.) (under the same computational cost): finer error bounds on the distances involved, and a more precise information on the location of the solution. Our results also compare favourably with recent and relevant ones in (I.K. Argyros, Concerning the “terra incognita” between convergence regions of two Newton methods, Nonlinear Anal. 62 (2005), pp. 179–194; I.K. Argyros, Computational Theory of Iterative Methods, in Studies in Computational Mathematics, Vol. 15, C.K. Chui and L. Wuytack, eds., Elsevier Publ. Co., New York, USA, 2007; I.K. Argyros, On the gap between the semilocal convergence domain of two Newton methods, Appl. Math. 34(2) (2007), pp. 193–204; I.K. Argyros, On the convergence region of Newton's method under Hölder continuity conditions, submitted for publication; I.K. Argyros, Estimates on majorizing sequences in the Newton–Kantorovich method, submitted for publication; F. Cianciaruso and E. DePascale, Newton–Kantorovich approximations when the derivative is Hölderian: Old and new results, Numer. Funct. Anal. Optim. 24 (2003), pp. 713–723; F. Cianciaruso and E. DePascale, Estimates of majorizing sequences in the Newton–Kantorovich method, Numer. Funct. Anal. Optim. 27(5–6) (2006), pp. 529–538; F. Cianciaruso and E. DePascale, Estimates of majorizing sequences in the Newton–Kanorovich method: A further improvement, J. Math. Anal. Appl. 322 (2006), pp. 329–335; N.T. Demidovich, P.P. Zabreiko, and Ju.V. Lysenko, Some remarks on the Newton–Kantorovich mehtod for nonlinear equations with Hölder continuous linearizations, Izv. Akad. Nauk Belorus 3 (1993), pp. 22–26 (in Russian). (E. DePascale and P.P. Zabreiko, The convergence of the Newton–Kantorovich method under Vertgeim conditions, A new improvement, Z. Anal. Anwendvugen 17 (1998), pp. 271–280.) and (L.V. Kantorovich and G.P. Akilov, Functional Analysis in Normed Spaces, Pergamon Press, Oxford, 1982; J.V. Lysenko, Conditions for the convergence of the Newton–Kantorovich method for nonlinear equations with Hölder linearizations, Dokl. Akad. Nauk BSSR 38 (1994), pp. 20–24 (in Russian); B.A. Vertgeim, On some methods for the approximate solution of nonlinear functional equations in Banach spaces, Uspekhi Mat. Nauk 12 (1957), pp. 166–169 (in Russian); Amer. Math. Soc. Transl. 16 (1960), pp. 378–382. (English Trans.).)     

A note on variable threshold concept lattices: Threshold-based operators are reducible to classical concept-forming operators

The present paper deals with formal concept analysis of data with fuzzy attributes. We clarify several points of a new approach of [S.Q. Fan, W.X. Zhang, Variable threshold concept lattice, Inf. Sci., accepted for publication] which is based on using thresholds in concept-forming operators. We show that the extent- and intent-forming operators from [S.Q. Fan, W.X. Zhang, Inf. Sci., accepted for publication] can be defined in terms of basic fuzzy set operations and the original operators as introduced and studied e.g. in [R. Belohlavek, Fuzzy Galois connections, Math. Logic Quarterly 45 (4) (1999) 497-504; R. Belohlavek, Concept lattices and order in fuzzy logic, Ann. Pure Appl. Logic 128 (2004) 277-298; S. Pollandt, Fuzzy Begriffe, Springer-Verlag, Berlin/Heidelberg, 1997]. As a consequence, main properties of the new operators from [S.Q. Fan, W.X. Zhang, Inf. Sci., accepted for publication], including the properties studied in [S.Q. Fan, W.X. Zhang, Inf. Sci., accepted for publication], can be obtained as consequences of the original operators from [R. Belohlavek, 1999; R. Belohlavek, 2004; S. Pollandt, 1997].     

Applications of Euclidean constructions to computer graphics

This paper presents an interactive graphics system called L.E.G.O. The purpose of L.E.G.O. is to model two- and three-dimensional objects using Euclidean geometry constructions. L.E.G.O. has a layered structure which makes it convenient to use, both for the experienced programmer and the novice. The programs may be written in a compiled language (C), written interactively in an interpreted language (LISP) or developed using a graphical interface in a multiple-window environment. Applications of L.E.G.O. include computer-assisted instruction of geometry and computer graphics, geometric modeling, and kinematic analysis. The use of imperative constructions and the powerful interface based on the idea of graphical programming are the most distinctive features of the system.     

Generation of templates for low-resolution text recognition using a hypothesis graph

We propose a recognition method of character-string images captured by portable digital cameras. A challenging task in character-string recognition is the segmentation of characters. In the proposed method, a hypothesis graph is used for recognition-based segmentation of the character-string images. The hypothesis graph is constructed by the subspace method, using eigenvectors as conditionally elastic templates. To obtain these templates, a generation-based approach is introduced in the training stage. Various templates are generated to cope with low-resolution. We have experimentally proved that the proposed scheme achieves high recognition performance even for low-resolution character-string images. The text was submitted by the authors in English. Hiroyuki Ishida. Received his B.S. and M.S. degrees from the Department of Information Engineering and from the Graduate School of Information Science, respectively, at Nagoya University. He is currently pursuing a Ph.D. in Information Science at Nagoya University. Ichiro Ide. Received his B.S. degree from the Department of Electronic Engineering, his M.S. degree from the Department of Information Engineering, and his Ph.D. from the Department of Electrical Engineering at the University of Tokyo. He is currently an Associate Professor in the Graduate School of Information Science at Nagoya University. Tomokazu Takahashi. Received his B.S. degree from the Department of Information Engineering at Ibaraki University, and his M.S. and Ph.D. from the Graduate School of Science and Engineering at Ibaraki University. His research interests include computer graphics and image recognition. Hiroshi Murase. Received his B.S., M.S., and Ph.D. degrees from the Graduate School of Electrical Engineering at Nagoya University. He is currently a Professor in the Graduate School of Information Science at Nagoya University. He received the Ministry Award from the Ministry of Education, Culture, Sports, Science and Technology in Japan in 2003. He is a Fellow of the IEEE.     

Correction to “Antiwindup Design With Guaranteed Regions of Stability: An LMI-Based Approach”

In the footnote of J.M. Gomes da Silva, Jr. and S. Tarbouriech (see ibid., vol.50, no.1, p.110, 2005), we have stated that the value of 61.29 obtained by Y.Y. Cao et al. (2002) was apparently incorrect. In fact, the different values come from the fact that the example considered by Y.Y. Cao is slightly different from the one by J.M. Gomes da Silva, Jr. and S. Tarbouriech (2005). Hence, the result presented by Y.Y. Cao is indeed correct and we apologize to the authors for the misunderstanding     

Tauberian theorems for statistically convergent double sequences

In [F. Moricz, Tauberian theorems for Cesàro summable double sequences, Studia Math. 110 (1994) 83-96], Moricz has proved some Tauberian theorems for Cesàro summable double sequences and deduced the Tauberian theorems of Landau [E. Landau, Über die Bedeutung einiger neuerer Grenzwertsätze der Herren Hardy and Axer, Prac. Mat.-Fiz. 21 (1910) 97-177] and Hardy [G.H. Hardy, Divergent Series, Univ. Press, Oxford 1956] type. In [J.A. Fridy, M.K. Khan, Statistical extension of some classical Tauberian theorems, Proc. Amer. Math. Soc. 128 (2000) 2347-2355], Fridy and Khan have given statistical extensions of some classical Tauberian theorems. The concept of statistical convergence for double sequences has recently been introduced by Mursaleen and Edely [M. Mursaleen, Osama H. H. Edely, Statistical convergence of double sequences, J. Math. Anal. Appl. 288 (2003) 223-231] and by Moricz [F. Moricz, Statistical convergence of multiple sequences, Arch. Math. 81 (2003) 82-89] independently. In this paper we give some Tauberian theorems for statistically convergent double sequences. We have also provided some examples including an example to Problem 1 of Moricz [F. Moricz, Tauberian theorems for Cesàro summable double sequences, Studia Math. 110 (1994) 83-96].     

Reviews

MARK FRESKO CONSULTANCY. Sources of digital information. British Library R&D Report 6102. London: British Library Research and Development Department, 1994. No ISBN given. No price indicated. 260 pp.

CHRIS CLARE and GORDON STUTELEY. Information systems — strategy to design. London: Chapman and Hall, 1995. ISBN 0 412 576708. £16.99.

POPE, IVAN. Internet UK. Hemel Hempstead: Prentice Hall International, 294 pp. ISBN 013 190950, £19.95. SCHOFIELD, SUE. UK Internet book. Wokingham: Addison‐Wesley, 301 pp. ISBN 0201 42766 4, £19.95.

RIMMER, STEVE. Planet Internet. New York: Windcrest, 1995. ISBN 0 8306 24724. £22.95 (pbk).

JILL H. ELLSWORTH and MATTHEW V. ELLSWORTH. The Internet business book. London: John Wiley & Sons, 1994. $22.95, 376pp. ISBN 0 471058092.

JOHN S. QUARTERMAN and SMOOT CARL‐MITCHELL. The e‐mail companion: communicate effectively via the Internet and other global networks. Addison‐Wesley, 1994. 318 pp. ISBN 0 201 40658 6. $19.95.

McCLURE, C.R., MOEN, W.E. and RYAN, J. Libraries and the Internet/NREN: perspectives, issues and challenges. London: Mecklermedia 1994. $35.00. ISBN 0 89736 824 7. McCLURE, C.R., BERTOT, J.C., and ZWEIZIG, D.L. Public libraries and the Internet: study results, policy issues and recommendations. Washington: National Commission on Libraries and Information Science, 1994. No price or ISBN given.

FRANCES BLOMELEY. Networks and network services: a user's guide. Immediate Publishing, 1994. ISBN 1–89831–00–03. 246 pp. £14.95.

NEIL SMITH (ed) ibraries, networks and Europe: a European networking study. British Library Research and Development Department, 1994. (LIR Series 101) 91 pp. ISBN 0 7123 3295 2. £25. (Distributed by Turpin Distribution Services Ltd, Blackhorse Road, Letchworth, Herts. SG6 1HN).

ALAN BRYANT. Creating successful bulletin board systems. Addison‐Wesley, 1994. ISBN 0–201–62668–3. $39.95.

Directory of electronic journals, newsletters and academic discussion lists. 4th ed. Compiled by Lisabeth A. King and Diane Kovacs, edited by Ann Okerson. Washington, DC: Association of Research Libraries, 1994. 575 pp. ISSN 1057–1337. $54 (paperback), $33 (ARL members).

THE BRITISH LIBRARY and ELECTRONIC PUBLISHING SERVICES LTD. Electronic publishing practice in the UK: LIR Report 95. University Press, Cambridge, 1994. 185 pp. ISBN 0 7123 3280 4. £30.00. (Distributed by Turpin Distribution Services, Blackhorse Road, Letchworth S96 1HN).

INTERNET WORLD'S On Internet 94: an international guide to electronic journals, newsletters, texts, discussion lists, and other resources on the Internet. edited by Tony Abbott with a Preface by Daniel P. Dem. Westport, London: Mecklermedia, 1994. £29.50 $45.00. ISBN 0–88736–929–4.

S. BANG. The Internet unleashed. Indianapolis: SAMS Publishing, 1994. $44.95. ISBN 0 672 30466 X.

GAIL K. DICKINSON, Selection and evaluation of electronic resources. Libraries Unlimited, 1994. ISBN 1 56308 098 2. £22.50.