Bücher veröffentlicht von Springer London

As software is very complex, we can only test a limited range of the possible states of the software in a reasonable time frame. In 1972, Dijkstra [1] claimed that 'program testing can be used to show the pres- ence of bugs, but never their absence' to persuade us that a testing approach alone is not acceptable. This frequently quoted statement represented our knowledge about software testing at that time, and after over 25 years intensive practice, experiment and research, although software testing has been developed into a validation and ver- ification technique indispensable to software engineering discipline, Dijkstra's state- ment is still valid. To gain confidence in the safety of software based systems we must therefore assess both the product and the process of its development. Testing is one of the main ways of assessing the product, but it must be seen, together with process assessment, in the context of an overall safety case. This book provides guidance on how to make best use of the limited resources available for testing and to maximise the contribution that testing of the product makes to the safety case. 1.1 Context The safety assurance of software based systems is a complex task as most fail- ures stem from design errors committed by humans. To provide safety assur- on the integrity of the system and put ance, evidence needs to be gathered forward as an argued case (the safety case) that the system is adequately safe.

The Internet contains so much information and data for astronomers that just finding what you want is a daunting task, and downloading can take hours of computer and telephone time.

Database theory is now in a mature state, and this book addresses important extensions of the relational database model such as deductive, temporal and object-oriented databases. It provides an overview of database modelling with the Entity-Relationship (ER) model and the relational model providing the pivot on which the material revolves. The main body of the book focuses on the primary achievements of relational database theory, including query languages, integrity constraints, database design, comput able queries and concurrency control. The most important extensions of the relational model are covered in separate chapters. This book will be useful to third year computer science undergraduates and postgraduates studying database theory, and will also be of interest to researchers and database practitioners who would like to know more about the ideas underlying relational dat abase management systems and the problems that confront database researchers.

but when we state that A 'equals' B , as well having to know what we mean by A and B we also have know what we mean by 'equals'. This section explores the role of observers; how different types of observ- er see different things as being equal, and how we can produce algo- rithms to decide on such equalities. It also explores how we go about writing specifications to which we may compare our SCCS designs. * The final section is the one which the students like best. Once enough of SCCS is grasped to decide upon the component parts of a design, the 'turning the handle' steps of composition and check- ing that the design meets its specification are both error-prone and tedious. This section introduces the concurrency work bench, which shoulders most of the burden. How you use the book is up to you; I'm not even going to suggest path- ways. Individual readers know what knowledge they seek, and course leaders know which concepts they are trying to impart and in what order.

Almost all amateur astronomers want to take photographs of the night sky. For all but the simplest star-trail pictures, this involves machinery - a telescope drive - to track the stars, essential to compensate for the rotation of the earth. The task becomes even more complicated when photographing very small or very faint objects that require high magnification or very long exposure times.Amateurs have many options according to their requirements, technical ability, and budget. Astrophotography for Amateurs looks at all the possibilities, including normal ("e;wet"e;) photography, CCD imaging, and modern techniques of computer enhancement. There are sections about photographing different classes of astronomical object from the Moon to faint nebulae, as well as a thorough look at the equipment needed.

Java is an object oriented language which allows you to create interactive Web pages, or to write applications which will run on any computer. Visual J++ gives you access to the power of Java with all the benefits of a modern visual development environment, for fast programming, and debugging. If you are new to Java or are an existing Java programmer who wants to switch to Visual J++, this book gives you all the essential information you need using lots of examples. Topics covered in this book include: the Java language, polymorphism, inheritance and encapsulation, graphics and animation, handling events, using files, exception handling, abstract windowing toolkit, the Java applet wizard and the resource wizards, debugging, and project management. Essential Visual J++ 6.0 fast is designed for professional developers or students who need to learn the maximum in the minimum time and to develop applications fast.

Many amateur astronomers make their own instruments, either because of financial considerations or because they are just interested. Amateur Telescope Making offers a variety of designs for telescopes, mounts and drives which are suitable for the home-constructor. The designs range from simple to advanced, but all are within the range of a moderately well-equipped home workshop. The book not only tells the reader what he can construct, but also what it is sensible to construct given what time is available commercially. Thus each chapter begins with reasons for undertaking the project, then looks at theoretical consideration before finishing with practical instructions and advice. An indication is given as to the skills required for the various projects. Appendices list reputable sources of (mail order) materials and components. The telescopes and mounts range from "e;shoestring"e; (very cheap) instruments to specialist devices that are unavailable commercially.

Why This Book, Why Now? It is now widely recognized that in the development of IT systems, the technology­ driven focus of the past has been eclipsed by a concern for user satisfaction and user productivity. It is well known that usability engineering helps make systems easier to use and more relevant to business needs. The benefits of producing usable computer systems have been proven in careful dollar or pound calculations and any computer user who has interacted with a system designed for usability will enthuse about the benefits and refuse to go back to the bad old days. More and more organizations are starting to take usability seriously. Along with Microsoft and Apple and other IT organizations, we now find banks, insur­ ance companies, multi-national pharmaceuticals and many other non-IT corpora­ tions starting to "do something about usability". It seems as if there is plenty of material explaining how to do it. HCI (Human Computer Interaction - or CHI, Computer Human Interaction in the USA) has been studied in academia for several years and there are a range of books on usability engineering for practi­ tioners from systems engineering and user interface design to usability evaluation. However, as many practitioners have found, although you do need to understand the theories and be familiar with the techniques, applying them in a commercial context is not a straightforward matter.

"e;l hope that people all around the world never forget what a wonderful thing it is to lie on your back and look up at the stars"e; Pete Seeger What is the fascination that constellations hold for people? There are probably as many different answers to that question as there are people. For many, though, the constella- tions are the stepping-off point into the fabulous, mind-bending discoveries and concepts of modern astronomy. For others it is their long and intriguing history that beckons. For some people the constellations provide the means for navigation and orientation over the surface of the Earth, and of course there are the millions who place some faith in horo- scopes. But for most people the patterns in the sky are a beautiful part of their environ- ment to be treasured alongside the forests, fields and rivers that make life worth living. However just as we are losing our green environment to pollution, so we are losing our sky. The glow from cities across the world swamps the stars in the night sky. Astronomers have had to retreat to remote mountain tops to escape that light pollution. The rest of us must make do with what is available. From the centre of a city, or any other brightly lit area, probably no stars at all will be visible even on the clearest of nights. From the suburbs, the brighter stars should normally be seen.

System design has conventionally been the province of engineers, and the approaches taken to the design of systems have conventionally led to formal specification of the system. The past decade or two has seen the rise of another approach, that of human-computer interaction (HCI). Given the number of incidents and accidents which are attributed to 'human error', it is sensible to develop an approach to system design which views humans as an essential element in the system. Thus, an important aspect of designing systems is the study of the interaction between humans and the technology that they use. In terms of bringing computers and computing to a wide audience, the 1980s were the boom years. The first personal computer (PC) was launched onto the market in February 1978, and since then, PCs have become a common-place feature of our homes, offices, schools, retail outlets, hospitals, banks, etc. Within Western society today, there are very few organisations that have not been infiltrated by computer technology, and few individuals who have not had experience of computers. However, the increase in use of computers has not been matched with a corresponding spread of training of users; much of the human-computer interaction research has sought to design systems which do not require special training, i. e. which people can simply walk up to and use. Not surprisingly, this has resulted in a number of difficulties; some of which have yet to be satisfactorily resolved.

This book addresses issues concerning the engineering of system prod- ucts that make use of computing technology. These systems may be prod- ucts in their own right, for example a computer, or they may be the computerised control systems inside larger products, such as factory automation systems, transportation systems and vehicles, and personal appliances such as portable telephones. In using the term engineering the authors have in mind a development process that operates in an integrated sequence of steps, employing defined techniques that have some scientific basis. Furthermore we expect the operation of the stages to be subject to controls and standards that result in a product fit for its intended purpose, both in the hands of its users and as a business venture. Thus the process must take account of a wide range of requirements relating to function, cost, size, reliabili- ty and so on. It is more difficult to define the meaning of computing technology. These days this involves much more than computers and software. For example, many tasks that might be performed by software running in a general purpose computer can also be performed directly by the basic technology used to construct a computer, namely digital hardware. However, hardware need not always be digital; we live in an analogue world, hence analogue signals appear on the boundaries of our systems and it can sometimes be advantageous to allow them to penetrate further.

PREFACE The FORTRAN programming language was designed in the 1950s and standardized in 1966. That version of the language was later called FORTRAN 66. FORTRAN 66 quickly developed into the most important programming language for the development of engineering and scientific applications. In 1978, the language was redesigned and standardized again and called FORTRAN 77. However, this FORTRAN version was not yet a modern language as far as software engineering and programming methodology were concerned. In 1991, a new version of the language was standardized. Its name is Fortran 90. This version is a powerful tool, in fact it is closer to the state of the art of high level problem oriented programming languages than other famous languages that are used for the same area of application. The next revision of the language is planned for 1995; it will be a minor revision of Fortran 90. The next major language revision is planned for the year 2000. This "e;Fortran90 Language Guide"e; is a comprehensible description of the com- plete Fortran 90 programming language as it is defined in the standard docu- ment [1]. It is already in accordance with the two corrigenda [2] [3] of the standard document. The standard document is a reference book for compiler writers and those experts who already know all about Fortran 90, but it is use- less for beginners and rather impractical even for experienced programmers.

Notations for Software Design aims to explain formal specification and design to practitioners in software development, and to set out the ingredients of a sound software design process. It examines COLD-1, which is currently being implemented by Philips in many of its business centres. The fact that it is a wide-spectrum language which supports many styles of specification makes it an excellent basis for the volume. It also examines some widely-used informal techniques, such as Venn diagrams and Petri nets, thus creating a strong link between current and future practice. Rather than proposing new pictorial notations the authors place existing ones into a coherent framework, and explain practical ways of exploiting them in conjunction with COLD-1.

Combustion is very much an interdisciplinary topic, drawing together elements of chemistry, fluid mechanics and heat transfer. It is an ingredient in many undergraduate degree programmes, ranging from a pivotal role in fuel science through to a component part of courses in chemical, process and building services engineering. For many students in those disciplines where combustion in heating plant is an important part of their studies, there are often problems in coming to grips with the basic principles underlying the combustion of hydrocarbon fuels. In particular, the concepts of chemical and related thermodynamic changes can prove difficult to assimilate. The scientific literature dealing with combustion tends to be rather polarised, with a wealth of literature aimed at the specialist reader, but at a basic level the fundamentals of this important process are often treated rather tersely in textbooks on thermodynamics. The objective of this book is to provide an introduction to the basic principles of the combustion of hydrocarbon fuels in heating plant for buildings and industrial processes. In those chapters where practice in problem solving can make a positive contribution to understanding, some numerical problems have been included. Acknowledging the ever-widening use of computers in technical education, a number of algorithms which can be easily coded up for solving numerical problems have been incorporated in the text. These can prove particularly useful in, for example, the calculation of certain fluid properties, either for use in hand calculation or for incorporation into larger programs.

An experienced pathologist, radiologist and clinician combine forces to review the recent literature on coloproctology and give a precis of the results. Their Highlights in Coloproctology are the ideal source for a clinician or researcher who wants a quick overview of the subject. The book highlights the papers that have had an impact on developments in the field and brings the reader up to date with modern references.

As computer technology is used to control critical systems to an increasing degree, it is vital that the methods for developing and understanding these systems are substantially improved. The mathematical and scientific foundations currently used are extremely limited which means that their correctness and reliability cannot be ensured to an acceptable level. Systems engineering needs to become a fully fledged scientific discipline and formal methods, which are characterised by their firm mathematical foundations, are playing a vital role in achieving this transition. This volume is based on the proceedings of the Formal Methods Workshop (FM91), held in Drymen, Scotland, 24-27 September 1991. This was the second workshop sponsored by the Canadian and US governments to address the role of formal methods in the development of digital systems. Traditionally, formal methods have evolved in isolation from more conventional approaches, and one of the aims of this workshop was to emphasise the benefits of integrating the two areas. The workshop concentrated on the themes of quality assurance, design methods and mathematical modelling techniques. Particular emphasis was given to safety and security applications. Among the topics covered in this volume are: what is a formal method?; social research on formal methods; current quality assurance methods and formal methods; a pragmatic approach to validation; integrating methods in practice; composition of descriptions; and topics in large program formal development. Formal Methods in Systems Engineering provides an overview of many of the major approaches to formal methods and the benefits which can result from them. It is relevant to academic and industrial researchers, industrial practitioners and government workers with an interest in certification.

Sexually Transmitted Diseases and AIDS covers all aspects of these diseases with extensive inclusion of dermatological conditions. The multiple choice questions and answers have been compiled by a highly experienced group of clinicians and researchers from two major STD/AIDS centres in the UK. These MCQs aim to help readers learn in an easy, effective and enjoyable way. The book is intended to make them think, to test themselves and check the standard of their knowledge in order to pass exams as well as to improve their clinical practice for their patients. It will be of use to all those in training in sexually transmitted diseases, doctors and nurses alike. The questions have been refined by representatives of these groups to provide interesting questions to test knowledge to different standards, whether to satisfy their own curiosity or their examiners'. It will be particularly helpful to those sitting examinations such as MRCP, MBBS, DipGUM as well as those attending specialist STD or AIDS courses.

In recent years a vast literature has been produced on the feasibility of Artificial Intelligence (AI). The topic most frequently discussed is the concept of intelligence, with efforts to demonstrate that it is or is not transferable to the computer. Only rarely has attention been focused on the concept of the artificial per se in order to clarify what kind, depth and scope of performance (including intelligence) it could support. Apart from the classic book by H.A. Simon, The Sciences of the Artificial, published in 1969, no serious attempt has been made to define a conceptual frame for understanding the intimate nature of intelligent machines independently of its claimed or denied human-like features. The general aim of this book is to discuss, from different points of view, what we are losing and what we are gaining from the artificial, particularly from AI, when we abandon the original anthropomorphic pretension. There is necessarily a need for analysis of the history of AI and the limits of its plausibility in reproducing the human mind. In addition, the papers presented here aim at redefining the epistemology and the possible targets of the AI discipline, raising problems, and proposing solutions, which should be understood as typical of the artificial rather than of an information-based conception of man.