Measurement Science for Engineers by M. J. Korsten, W. Otthius, F. van der Heijden · ISBN: 1903996589 · Publisher: Elsevier Science & Technology Books · Pub. Date: June 2004 Preface Throughout history, measurement has played a vital part in the development of society, and its significance is still growing with the ongoing advances in tech- nology. The outcome of a measurement may have important implications for the resultant actions. The correct execution of a measurement is, therefore, highly important, making heavy demands not only on the executor's skills but also on the designer's competences to creme measurement systems with the highest possible performance. This book on measurement science is adapted from a course book on measurement and instrumentation, used by undergraduate students in electrical engineering at the University of Twente, The Netherlands. It deals with basic concepts of elec- tronic measurement systems, the functionality of their subparts and the interactions between them. The most important issue of all is the quality of the measurement result. How to design a measurement system or instrument with the highest per- formance under the prevailing conditions. How to get the most of the system in view of its technical limitations. How to minimize interference from the environment. And finally: how to evaluate the measurement result and account for the remaining errors. A course book cannot give the ultimate answer to such questions. Its intention is merely to offer basic knowledge about the physical and instrumentation aspects of measurement science, the availability and characteristics of the major measure- ment tools and how to use them properly. More importantly, the book tries to make students aware of the variety of difficulties they may encounter when setting up and using a measurement system and make them conscious of the fact that a meas- urement result is always error-ridden. Solving such problems is not only a matter of knowledge; experimental skills and experience are even important to arrive at the specified performance. To that end, the course in measurement and instrument- ation of which this book is a consequence, is accompanied by a series of practical exercises, directed to the evaluation of sensor characteristics, signal processing and finally the total measurement system. The organization of the book is as follows. Chapter 1 is an introductory chapter in which concepts of measurement science and the general architecture of a measure- ment system are described. In Chapter 2 some fundamental aspects of measurement science are reviewed: the international system of units, measurement standards and physical quantities and their relations. Measurement errors and uncertainty are discussed extensively in Chapter 3; it includes the basic elements of probability Preface vii theory, methods to analyse and evaluate uncertainty and general techniques to minimize measurement errors. Chapters 4, 5 and 6 deal with signal conditioning and conversion: Chapter 4 is on analogue signal conditioning (amplification, filtering, modulation); Chapter 5 on digital signal conditioning (sampling, multiplexing and digital operations); and Chapter 6 on the conversion from analogue tot digital and vice versa. For each (physical) quantity a multitude of sensing strategies is available. In the next three chapters the major sensing methods are reviewed: in Chapter 7 we discuss the measurement of electrical, magnetic, thermal and optical quantities; in Chapter 8 mechanical quantities and in Chapter 9 chemical quantities. Measurement of multi- dimensional geometry is performed by imaging: the result is some kind of image in some domain. How these images are acquired and can be interpreted are the topics of Chapter 10. Finally, Chapter 11 covers particular aspects of system design and virtual instrumentation. The book is written by a team of authors, all from the Department of Electrical Engineering, University of Twente. Chapters 3 (uncertainty) and 10 (imaging) are authored by F van der Heijden, Chapters 5 (digital signal conditioning) by M Korsten, Chapter 9 (chemical quantities) by W Olthuis and the remainder by P Regtien. V Pop contributed to the section on virtual instruments in Chapter 11. Reading this book requires some basic knowledge of calculus, complex functions, physics and electronics, about equivalent to the first term undergraduate level. As with any course book, this one covers just a selected number of issues from an otherwise wide area. Connection to other relevant literature has been made by adding a short list of books at the end of each chapter, with a short indication of the subject and level. The enthusiastic reader may consult the cited references to the scientific literature for more detailed information on the subjects concerned. Paul P L Regtien University of Twente, The Netherlands April 2004 Foreword Measurement, and the instrumentation by which it is implemented, is the basic tool of natural science and a key enabling technology. Measurement is the essential means by which we acquire scientific and technical knowledge on which modern society and the economy depend. Further, all aspects of technology rely on measurement and could not function effectively without it. Driven by technical progress and by economic and social requirements, meas- urement and its instrumentation are advancing rapidly in capability and range of application. A few examples of the main areas of application illustrate the significance of modem measurement technology. Modem manufacture is based to a substantial extent on the application of measurement and measuring systems. They are an essential component of automation, which both raises productivity and enhances quality. Application of measuring instrumentation has extended from the automatic control of continuous processes to applications in the automation of the manufacture of discrete engineering products, and to more general uses of robotics. Transport, in the air, on the sea, and on land, is to an increasing extent relying on the use of advanced measuring systems for navigation and propulsion management. Instrumentation has an ever-increasing role in providing the security of property from fire and theft. Modem medicine increasingly relies on advanced instrumentation for diagnosis and some aspects of therapy such as intensive care. Finally, we must mention the importance of instrumentation in the safeguarding of the environment. Monitoring of pollution, ranging from the analysis of noxious chemicals to the measurement of noise and the remote sensing from space are two leading areas of application. It should also be added that the design and manufacture of measuring equipment and systems is an important economic activity. Given the central and far-ranging importance of measurement and instrumentation, all engaged in technology require a sound education and training in this field. This is widely recognised. The structure and content of appropriate education in measurement and instrument- ation is the subject of international interest and debate. Professor Paul Regtien, as Chairman of the Technical Committee on Education and Training of the International Measurement Confederation, is spearheading this debate. Some of the principal problems in designing and delivering education in the field are as follows. Firstly, it is generally accepted that education in measurement and instru- mentation should inculcate a well-organised body of basic concepts and principles Foreword ix and that it should also foster a competence to apply that fundamental knowledge in practice through the study of particular measurement equipment and applica- tions. There is continuing discussion conceming the establishment of the nature and scope of the fundamental concepts and principles of the domain and of the framework into which they are organised. There are debates concerning the nature of the discipline; whether it is to be viewed from an information perspective regard- ing measurement as an information acquisition and handling process, or whether to focus on metrological problems of unit, standards, calibration and uncertainty. There is an issue of the autonomy of the domain and of the extent to which it is related to other disciplines; to physical science in respect of sensors and the sensing process, and to information technology in respect of information handling in meas- uring systems. There are issues of the nature of the balance between the teaching of abstract principles and the provision of a survey of practice. Finally, there is a growing recognition that education in measurement and instrumentation must be design-orientated, raising the question of how this influences formal presentation of the subject. The form of education in any technology depends on the nature and level of the competence for which students are being educated. Further it requires a choice from an increasing arsenal of means of teaching: formal presentations, web-based information, laboratories, simulation and teaching machines. While progress in educational tools is fuelling great interest, it is recognised that core of knowledge must be taught through formal structured presentations. Regarding the nature of competence for which technical personnel are being educated trained and developed it is necessary to recognise different levels of com- petence. We may distinguish craftsmen, technicians, technician engineers, and scientific engineers. The names are not agreed in all languages and cultures, but the levels