The Shadow Function for Rough Surfaces

For many remote sensing applications it is beneficial to know how the amount of shadows on a surface depends on illumination. Many natural surfaces (planetary surfaces being an example) may be successfully described by a fractal model. While the fractal shadowing function can be easily calculated experimentally, to date no rigorous analytical model of self-shadowing on a fractal surface exists. In this paper we offer an integral form of the shadowing function for fractal surfaces with different fractal and roughness parameters. The analysis is based on working out the covariance matrix for an arbitrarily long sequence of heights in a fractal profile.Svetlana Barsky received her BSc degree in Mathematics and Applied Mathematics from Novosibirsk State University, Russia, in 1992, and her MSc and PhD degrees from the University of Surrey, UK, in 1999 and 2003 respectively. Since then she has been working as a research fellow at the Centre for Vision, Speech and Signal Processing of the School of Electronics and Physical Sciecnes of Surrey University.Maria Petrou studied Physics at the Aristotle University of Thessaloniki, Greece, Applied Mathematics in Cambridge and she did her PhD in the Institute of Astronomy in Cambridge, UK. She has been working on image processing and computer vision since 1986. She has been the Professor of Image Analysis since 1998 and leads a group of 20 researchers on this topic in Surrey University. She has published more than 250 scientific papers, on Astronomy, Remote Sensing, Computer Vision, Machine Learning, Colour analysis, Industrial Inspection, Medical Signal and Image Processing. She has co-authored a book “Image Processing: the fundamentals” published by John Wiley in 1999 and reprinted in 2000 and 2003, and numerous book chapters. She is a Fellow of the Royal Academy of Engineering, Fellow of IEE and Fellow of IAPR. She has served as the Chairman of the Technical Committee for Remote Sensing of IAPR, the Chairman of the British Machine Vision Association (BMVA), as an Associate Editor of IEEE Transactions on Image Processing, as the Newsletter Editor of IAPR and is currently the treasurer of IAPR and an Honorary Editor of IEE Electronics Letters. A full list of publications and other details can be found in     

Verification of Mondex electronic purses with KIV: from transactions to a security protocol

The Mondex case study about the specification and refinement of an electronic purse as defined in the Oxford Technical Monograph PRG-126 has recently been proposed as a challenge for formal system-supported verification. In this paper we report on two results. First, on the successful verification of the full case study using the KIV specification and verification system. We demonstrate that even though the hand-made proofs were elaborated to an enormous level of detail we still could find small errors in the underlying data refinement theory, as well as the formal proofs of the case study. Second, the original Mondex case study verifies functional correctness assuming a suitable security protocol. We extend the case study here with a refinement to a suitable security protocol that uses symmetric cryptography to achieve the necessary properties of the security-relevant messages. The definition is based on a generic framework for defining such protocols based on abstract state machines (ASMs). We prove the refinement using a forward simulation. J. C. P. Woodcock     

A metamodel for modeling system features and their refinement, constraint and interaction relationships

This paper presents a metamodel for modeling system features and relationships between features. The underlying idea of this metamodel is to employ features as first-class entities in the problem space of software and to improve the customization of software by explicitly specifying both static and dynamic dependencies between system features. In this metamodel, features are organized as hierarchy structures by the refinement relationships, static dependencies between features are specified by the constraint relationships, and dynamic dependencies between features are captured by the interaction relationships. A first-order logic based method is proposed to formalize constraints and to verify constraints and customization. This paper also presents a framework for interaction classification, and an informal mapping between interactions and constraints through constraint semantics. Hong Mei received the BSc and MSc degrees in computer science from the Nanjing University of Aeronautics and Astronautics (NUAA), China, in 1984 and 1987, respectively, and the PhD degree in computer science from the Shanghai Jiao Tong University in 1992. He is currently a professor of Computer Science at the Peking University, China. His current research interests include Software Engineering and Software Engineering Environment, Software Reuse and Software Component Technology, Distributed Object Technology, and Programming Language. He has published more than 100 technical papers. Wei Zhang received the BSc in Engineering Thermophysics and the MSc in Computer Science from the Nanjing University of Aeronautics and Astronautics (NUAA), China, in 1999 and 2002, respectively. He is currently a PhD student at the School of Electronics Engineering and Computer Science of the Peking University, China. His research interests include feature-oriented requirements modeling, feature-driven software architecture design and feature-oriented software reuse. Haiyan Zhao received both the BSc and the MSc degree in Computer Science from the Peking Univeristy, China, and the Ph.D degree in Information Engineering from the University of Tokyo, Japan. She is currently an associate professor of Computer Science at the Peking University, China. Her research interests include Software Reuse, Domain Engineering, Domain Specific Languange and Program Transformation.     

Design and verification of fault tolerant systems with CSP

Summary By means of an example, we present a formal method based on CSP to design fault tolerant systems. This method combines algebraic and assertional techniques to achieve complete formal verification of the fault tolerant system's correctness properties. Verification steps are executed in parallel with top-down design, so that correctness proofs can be clearly structured and their completeness easily checked. In this way formal verification is applicable not only to small examples but to reasonably large systems. Jan Peleska was born in 1958 in Hamburg, received his Diploma in Mathematics from the University of Hamburg in 1981 and a Ph.D. in Mathematics in 1982. From 1981 to 1984 he worked in research and software development projects in the field of accoustics. Since 1984 he has been working with Philips and DST in Kiel in the field of distributed information systems. Peleska's current research interests include fault tolerant systems, distributed database systems and formal design and verification methods.     

Efficient detection of a class of stable properties

Summary We present a general protocol for detecting whether a property holds in a distributed system, where the property is a member of a class of stable properties we call thelocally stable properties. Our protocol is based on a decentralized method for constructing a maximal subset of the local states that are mutually consistent, which in turn is based on a weakened version of vector time stamps. The structure of our protocol lends itself to refinement, and we demonstrate its utility by deriving some specialized property-detection protocols, including two previously-known protocols that are known to be efficient. Laura Sabel received the BSE degree from Princeton University in 1989 and the MS degree in Computer Science from Cornell University in 1992. She is currently a PhD student in the Department of Computer Science at Cornell University. Her research interests include fault-tolerance and distributed systems. she is the recipient of an AT&T PhD Scholarship. Keith Marzullo received his Ph.D. degree in electrical engineering from Stanford University in 1984. He is an associate professor in the Computer Science and Engineering Department at the University of California, San Diego. His research interests are in the area of fault-tolerance in both asynchronous and real-time distributed systems. He has consulted on several projects including the IBM Air Traffic Control System, and is an associate editor for IEEE Transactions on Software Engineering.This work was supported by the Defense Advanced Research Projects Agency (DoD) under NASA Ames grant number NAG 2-593, and by grants from IBM and Siemens. The views, opinions, and findings contained in this report are those of the authors and should not be construed as an official Department of Defense position, policy, or decision. An earlier version of this paper appears in theProceedings of the 5th International Workshop on Distributed Systems, October 1991, Springer-Verlag LNCS Vol. 579This author is also supported by an AT&T PhD Scholarship     

CYCLON: Inexpensive Membership Management for Unstructured P2P Overlays

Unstructured overlays form an important class of peer-to-peer networks, notably when content-based searching is at stake. The construction of these overlays, which is essentially a membership management issue, is crucial. Ideally, the resulting overlays should have low diameter and be resilient to massive node failures, which are both characteristic properties of random graphs. In addition, they should be able to deal with a high node churn (i.e., expect high-frequency membership changes). Inexpensive membership management while retaining random-graph properties is therefore important. In this paper, we describe a novel gossip-based membership management protocol that meets these requirements. Our protocol is shown to construct graphs that have low diameter, low clustering, highly symmetric node degrees, and that are highly resilient to massive node failures. Moreover, we show that the protocol is highly reactive to restoring randomness when a large number of nodes fail.Spyros Voulgaris is a PhD student in the Computer Systems department at the Vrije Universiteit Amsterdam. He received his MSc degree from the University of Michigan, Ann Arbor, and his BSc degree from the University of Patras, Greece. His research involves peer-to-peer systems, epidemic protocols, and ad-hoc networks. He is a scholarship recipient of the Greek State Scholarships Foundation (IKY) and the Alexander Onassis Foundation.Daniela Gavidia is a PhD student in the Computer Systems group at the Vrije Universiteit Amsterdam. She received her MSc degree from the Universiteit van Amsterdam. Her research interests include peer-to-peer systems and ad-hoc networks. Her recent work focuses on information dissemination in ad-hoc environments.Maarten van Steen is professor of Computer Science at the Vrije Universiteit Amsterdam. His research concentrates on large-scale distributed systems, notably content delivery networks and peer-to-peer systems. He is senior member of the IEEE and member of the ACM.     

The design of S-boxes by simulated annealing

Substitution boxes (S-boxes) are important components in many modern-day symmetric key ciphers. Their study has attracted a great deal of attention over many years. The emergence of a variety of cryptosystem attacks has shown that substitutions must be designed with great care. Some general criteria such as high non-linearity and low autocorrelation have been proposed (providing some protection against attacks such as linear cryptanalysis and differential cryptanalysis). The design of appropriate S-boxes is a difficult task; several criteria must be traded off and the design space is huge. There has been little application of evolutionary search to the development of S-boxes. In this paper we show how a cost function that has found excellent single-out put Boolean functions can be generalised to provide improved results for small S-boxes. John A. Clark: He is Professor of Critical Systems at the University of York, where he leads the software testing, security and cryptography work. Much of this has been concerned with the application of meta-heuristic search. Jeremy L. Jacob: He has a BSc. in Mathematics from the University of Hull, England, M.Sc. and D. Phil. in Computation from the University of Oxford, England and now works for the Univerity of York. His research interests include modelling secure systems and software engineering practices for secure systems. Susan Stepney: She is Professor of computer Science at the University of York, and leads the Non-Standard Computation research group there. She is a member of the ACM, Fellow of the British Computer Society, and moderator of the UKCRC Grand Challenge in Non-Classical Computation. Her main research interests include novel applications of nature-inspired computation, modelling self-organising complex systems and designing and reasoning about emergent properties.     

Statistical methods for detecting latent periodicity patterns in biological sequences: The case of small-size samples

An original spectral-statistical approach for detecting latent periodicity in biological sequences is proposed. This approach can be applied under conditions of limited statistical sample. It allows one to avoid redundancy and instability when identifying the latent periodicity structure. The optimality of the periodicity-pattern-size estimates obtained for approximate tandem repeats on the basis of the spectral-statistical approach is demonstrated in practical examples. Maria Borisovna Chaley was born in 1963 and graduated from the Moscow Institute of Physics and Technology in 1988 (M.Sc.). She received her PhD in biophysics in 1993 and became a docent in bioinformatics in 2003. At the present time, she is a senior research fellow at the Institute of Mathematical Biology Problems of the Russian Academy of Sciences. Her research interests include bioinformatics, genetic text analysis, and molecular evolution. She is the author of over 40 research publications, including 14 journal articles. Nafisa Nailovna Nazipova was born in 1960 and graduated from the Department of Computational Mathematics and Cybernetics of Lenin Kazan State University in 1982 (MSc.). She received her PhD in physics and mathematics (mathematic modeling, numerical methods, and program complexes) in 2002. At the present time, she is the head of the bioinformatics laboratory at the Institute of Mathematical Biology Problems of the Russian Academy of Sciences. Her research interests include bioinformatics and the structural and functional organization of genetic sequences. She is the author of over 35 research publications, including 9 papers in refereed journals and 2 book chapters. Vladimir Andreyevich Kutyrkin was born in 1952 and graduated from the Department of Mechanics and Mathematics of Lomonosov Moscow State University in 1974 (MSc.). He received his PhD in physics and mathematics in 1995. At the present time, he is a docent of Bauman Moscow State Technical University. His research interests include applied mathematical statistics, computational and discrete mathematics, and bioinformatics. He is the author of over 20 research publications, including 11 journal papers.     

The Efficiency of Critical Slicing in Fault Localization

In software testing, developing effective debugging strategies is important to guarantee the reliability of software under testing. A heuristic technique is to cause failure and therefore expose faults. Based on this approach mutation testing has been found very useful technique in detecting faults. However, it suffers from two problems with successfully testing programs: (1) requires extensive computing resources and (2) puts heavy demand on human resources. Later, empirical observations suggest that critical slicing based on Statement Deletion (Sdl) mutation operator has been found the most effective technique in reducing effort and the required computing resources in locating the program faults. The second problem of mutation testing may be solved by automating the program testing with the help of software tools. Our study focuses on determining the effectiveness of the critical slicing technique with the help of the Mothra Mutation Testing System in detecting program faults. This paper presents the results showing the performance of Mothra Mutation Testing System through conducting critical slicing testing on a selected suite of programs. Zuhoor Abdullah Al-Khanjari is an assistant professor in the Computer Science Department at Sultan Qaboos University, Sultanate of Oman. She received her BSc in mathematics and computing from Sultan Qaboos University, MSc and PhD in Computer Science (Software Engineering) from the University of Liverpool, UK. Her research interests include software testing, database management, e-learning, human-computer interaction, programming languages, intelligent search engines, and web data mining and development. ~Currently, she is the coordinator of the software engineering research group in the Department of Computer Science, College of Science, Sultan Qaboos University. She is also coordinating a program to develop e-learning based undergraduate teaching in the Department of Computer Science. Currently she is holding the position of assistant dean for postgraduate studies and research in the College of Science, Sultan Qaboos University, Sultanate of Oman. Martin Woodward is a Senior Fellow in the Computer Science Department at the University of Liverpool in the UK. After obtaining BSc and Ph.D. degrees in mathematics from the University of Nottingham, he was employed by the University of Oxford as a Research Assistant on secondment to the UK Atomic Energy Authority at the Culham Laboratory. He has been at the University of Liverpool for many years and initially worked on the so-called ‘Testbed’ project, helping to develop automated tools for software testing which are now marketed successfully by a commercial organisation. His research interests include software testing techniques, the relationship between formal methods and testing, and software visualisation. He has served as Editor of the journal ‘Software Testing, Verification and Reliability’ for the past thirteen years. Haider Ramadhan is an associate professor in the Computer Science Department at Sultan Qaboos University. He received his BS and MS in Computer Science from University of North Carolina, and the PhD in Computer Science and AI from Sussex University. His research interests include visualization of software, systems, and process, system engineering, human-computer interaction, intelligent search engines, and Web data mining and development. Currently, he is the chairman of the Computer Science Department, College of Science, Sultan Qaboos University, Sultanate of Oman. Swamy Kutti (N. S. Kutti) is an associate professor in the Computer Science Department at Sultan Qaboos University. He received his B.E. in Electronics Engineering from the University of Madras, M.E. in Communication Engineering from Indian Institute of Science (Bangalore), and the MSc in Computer Science from Monash University (Australia) and PhD in Computer Science from Deakin University (Australia). His research interests include Real-Time Programming, Programming Languages, Program Testing and Verification, eLearning, and Distributed Operating Systems.     

Call classification using recurrent neural networks, support vector machines and finite state automata

Our objective is spoken-language classification for helpdesk call routing using a scanning understanding and intelligent-system techniques. In particular, we examine simple recurrent networks, support-vector machines and finite-state transducers for their potential in this spoken-language-classification task and we describe an approach to classification of recorded operator-assistance telephone utterances. The main contribution of the paper is a comparison of a variety of techniques in the domain of call routing. Support-vector machines and transducers are shown to have some potential for spoken-language classification, but the performance of the neural networks indicates that a simple recurrent network performs best for helpdesk call routing. Sheila Garfield received a BSc (Hons) in computing from the University of Sunderland in 2000 where, as part of her programme of study, she completed a project associated with aphasic language processing. She received her PhD from the same university, in 2004, for a programme of work connected with hybrid intelligent systems and spoken-language processing. In her PhD thesis, she collaborated with British Telecom and suggested a novel hybrid system for call routing. Her research interests are natural language processing, hybrid systems, intelligent systems. Stefan Wermter holds the Chair in Intelligent Systems and is leading the Intelligent Systems Division at the University of Sunderland, UK. His research interests are intelligent systems, neural networks, cognitive neuroscience, hybrid systems, language processing and learning robots. He has a diploma from the University of Dortmund, Germany, an MSc from the University of Massachusetts, USA, and a PhD in habilitation from the University of Hamburg, Germany, all in Computer Science. He was a Research Scientist at Berkeley, CA, before joining the University of Sunderland. Professor Wermter has written edited, or contributed to 8 books and published about 80 articles on this research area.     

A state-based approach to communicating processes

Communicating processes, which may exhibit nondeterministic behaviour, are specified as state-transition systems. Equivalence and refinement relations are defined in terms of the failures model of processes. Downward and upward simulation are considered as proof methods for refinement. Various operators on processes are defined and their refinement rules established. Mark Josephs joined the Programming Research Group at Oxford University in 1983, upon graduating from London University with a degree in Mathematics. One year later he was awarded the Master's degree in Computation. He received the doctorate in 1986 for his work in functional programming and took up a Visiting Scientist post at IBM Yorktown Heights in their Specification and Design Languages Group. He has now returned to the P.R.G. as a S.E.R.C. Research Officer.     

A machine vision system for quantifying velocity fields in complex rock models

In this paper we describe a machine vision system capable of high-resolution measurement of fluid velocity fields in complex 2D models of rock, providing essential data for the validation of the numerical models which are widely applied in the oil and petroleum industries. Digital models, incorporating the properties of real rock, are first generated, then physically replicated as layers of resin or aluminium (200 mm × 200 mm) encapsulated between transparent plates as a flowcell. This configuration enables the geometry to be permeated with fluid and fluid motion visualised using particle image velocimetry. Fluid velocity fields are then computed using well-tested cross-correlation techniques. Rachel Cassidy is a Research Associate in Geophysics at the University of Ulster. Dr. Cassidy's research interests include percolation theory and its application to fluid flow in fractured rock, the fractal and multifractal properties of natural phenomena and the development of experimental techniques for investigating fluid flow in porous fractured media with realistic structure and exhibiting scale invariance. She is currently involved in the development of molecular tracer techniques for characterising reservoir heterogeneity. Philip Morrow is currently a Senior Lecturer in the School of Computing and Information Engineering at the University of Ulster. Dr. Morrow has a BSc in Applied Mathematics and Computer Science, an MSc in Electronics and a PhD in Parallel Image Processing, all from the Queen's University of Belfast. His main research interests lie in image processing, computer vision and parallel/distributed computing. He has published over 65 research papers in these areas. John McCloskey is Professor of Geophysics and Head of the School of Environmental Sciences at the University of Ulster. Prof. McCloskey's research interests are in the application of ideas of chaos and complexity to a variety of geophysical problems including earthquake dynamics and fluid flow in fractured porous rock. He has published over 100 articles and is a regular contributor to international press on matters connected with earth science.     

多媒体会议系统的发言控制协议研究

在多媒体会议中,参与成员需要协调由谁获得向会议发送数据权力,这就是发言权控制。发言权控制是会议控制的一个重要内容,它直接关系到会议的服务质量。文中通过分析发言权控制的典型交互行为,设计了通用发言权控制协议（GFCP）并采用概率CSP加以形式化描述,验证了协议的逻辑正确性和稳定性,同时,该文还在协议实现框架中讨论了GFCP的公平性和缩放性等问题,给出了相应的解决方案。     

Image enhancement by total variation quasi-solution method

A new method of image restoration based on the quasi-solution method for a compact set of functions with bounded total variation is introduced. Application of this method does not require estimation of the noise level, which is necessary to choose the regularization parameter in the Tikhonov regularization method. The approbation of this method with test images shows its effectiveness for image deringing. The text was submitted by the authors in English. Andrey S. Krylov. Born 1956. Graduated from the Faculty of Computational Mathematics and Cybernetics, Moscow State University (MGU). Received the degree of PhD in 1983. Currently an associate professor and head of the Laboratory of Mathematical Methods of Image Processing at the Faculty of Computational Mathematics and Cybernetics, MGU. His main research interests lie in mathematical methods of multimedia data processing. Vladimir N. Tsibanov. Born 1982. Graduated from the Faculty of Computational Mathematics and Cybernetics, Moscow State University (MGU). He is currently a PhD student at the Faculty of Computational Mathematics and Cybernetics, MGU. His main research interests lie in variational methods in image processing. Alexander M. Denisov. Born 1946. Graduated from the Faculty of Mechanics and Mathematics, Moscow State University (MGU). Received the degrees of PhD in 1972 and doctor of science in 1987. Currently a professor and head of the Chair of Mathematical Physics of the Faculty of Computational Mathematics and Cybernetics, MGU. His main research interests lie in inverse and ill-posed problems in mathematical physics.     

Presenting software engineering results using structured abstracts: a randomised experiment

When conducting a systematic literature review, researchers usually determine the relevance of primary studies on the basis of the title and abstract. However, experience indicates that the abstracts for many software engineering papers are of too poor a quality to be used for this purpose. A solution adopted in other domains is to employ structured abstracts to improve the quality of information provided. This study consists of a formal experiment to investigate whether structured abstracts are more complete and easier to understand than non-structured abstracts for papers that describe software engineering experiments. We constructed structured versions of the abstracts for a random selection of 25 papers describing software engineering experiments. The 64 participants were each presented with one abstract in its original unstructured form and one in a structured form, and for each one were asked to assess its clarity (measured on a scale of 1 to 10) and completeness (measured with a questionnaire that used 18 items). Based on a regression analysis that adjusted for participant, abstract, type of abstract seen first, knowledge of structured abstracts, software engineering role, and preference for conventional or structured abstracts, the use of structured abstracts increased the completeness score by 6.65 (SE 0.37, p < 0.001) and the clarity score by 2.98 (SE 0.23, p < 0.001). 57 participants reported their preferences regarding structured abstracts: 13 (23%) had no preference; 40 (70%) preferred structured abstracts; four preferred conventional abstracts. Many conventional software engineering abstracts omit important information. Our study is consistent with studies from other disciplines and confirms that structured abstracts can improve both information content and readability. Although care must be taken to develop appropriate structures for different types of article, we recommend that Software Engineering journals and conferences adopt structured abstracts.

A refinement calculus for specifications in Hennessy-Milner logic with recursion

This paper is about specification and verification of processes, modelled as CCS-agents. We show, by means of examples that Hennessy-Milner Logic (HML) with recursion is a suitable language for expressing implicit or partial specifications. By extending this specification language withrefinement operators, i.e. operators that describe the internal structure of a system, we obtain a calculus for stepwise refinement of agents from a specification in HML to a realisation in CCS. The method is demonstrated by proving the alternating-bit protocol under weak assumptions about the unreliable media.This paper has also be presented at the BCS-FACS workshop on Specification and Verification of Concurrent Systems, University of Stirling, July 1988, under the title: Hennessy-Milner logic with recursion as a specification language, and a refinement calculus based on it.     

The compositional approach to sequential consistency and lazy caching

Summary. The lazy caching protocol proposed by Afek, Brown and Merritt [ABM93], is explained and formally proven correct by means of compositional methods. The protocol is decomposed into four simple protocols, which are of interest on their own. A top level proof is given that is to a large extent independent of the particular model used for the more detailed proofs and allows for a number of generalizations of the original lazy caching protocol. Detailed proofs of safety and liveness properties are given using CSP and trace logic.     

Can current protocol verification techniques guarantee correctness?

In the past 15 years the alternating-bit protocol has been perhaps the most widely verified protocol, the benchmark of protocol verification techniques; is it really correct? We claim that the answer is negative. The problem is that existing concepts of correctness do not capture an important sense in which a protocol may be incorrect. Specifically, although protocol goals (e.g., delivering messages) may be attained eventually, the time periods to achieve these goals may increase indefinitely. A notion of correctness that allows one to consider the probability of reaching a goal as well as the time or computational effort required to achieve the goal is required. We suggest a novel approach to protocol correctness which unifies functional and performance considerations using a recently proposed probabilistic semantics for programs.     

Specification and analysis of a composition of protocols

A composite protocol constructed from two smaller protocols is formally specified, and a proof of correctness is given. The formal specification of the composite protocol is constructed from the formal specification of the two protocols from which it is composed, and the proof of the composite protocol is an expansion of the correctness proofs of the two smaller protocols.

The composite protocol is a data-compression protocol which combines two wellknown data-compression protocols, achieving further compression.

The protocol processes are specified as a set of actions, each of which has a guard, or Boolean expression. An action may take place only if its guard is true and is an atomic event. Verification is accomplished by proving that the set of states satisfying an invariant is closed.