bluuebunny/crossref_metadata_2025 huggingface dataset:
DSP
Tools
Authors: Paterson‐Stephens Iain
Published: August 2008

In this section, a number of issues are considered relating to the range of software tools that may be used during the design and development of DSP‐based applications. Software tools that could be used include algorithm design and visualization packages such as MATLAB and Simulink that help the designer to understand and tackle a signal‐processing problem. Other software tools can then be used to help move a theoretical design that exists only in simulation across to a target device for integration into a real‐world signal processing system; to verify and optimize the operation of the final working DSP system.
Principles of
DSP
Hardware Design
Authors: Paterson‐Stephens Iain
Published: August 2008

When designing DSP hardware to suit a particular application, a number of issues must be considered regarding the algorithms to be used, interfacing requirements, and system architecture. The performance of the required algorithms will be greatly affected by the processing demands of the complete DSP system and it is important to take a holistic approach when setting out the design strategy at the start. This section outlines some of the initial steps and gives an overview of the tools and techniques that can be used to ease the development of new DSP hardware. Information about testing and evaluation of the DSP system design and its real‐time performance is also presented.
Nature and Scope ofAITechniques
Authors: Abraham Ajith
Published: August 2008

The field of computational intelligence (artificial intelligence) has evolved with the objective of developing machines that can think like humans. As evident, the ultimate achievement in this field would be to mimic or exceed human cognitive capabilities including reasoning, understanding, learning, and so on. Computational intelligence includes neural networks, fuzzy inference systems, global optimization algorithms, probabilistic computing, swarm intelligence and so on. This article introduces the fundamental aspects of the key components of modern computational intelligence.
Artificial Neural Networks
Authors: Abraham Ajith
Published: August 2008

Artificial neural networks are useful tools that have been applied successfully in a broad range of signal‐processing problems. From a signal‐processing perspective, their ability to adapt continuously to new data allows them to track changes in a signal over time, and their ability to learn from arbitrary, noisy data permits them to solve problems that cannot be handled adequately with some of the conventional statistical techniques. This chapter presents the fundamental principles of neural network modeling and illustrates some of the most commonly used neural network architectures for practical problem solving.
Rule‐Based Expert Systems
Authors: Abraham Ajith
Published: August 2008

The success of intelligent signal processing systems lies in their capabilities of logical reasoning, decision making, adaptation, self‐organization and communication in different modalities: speech, image, language, and so on. This article describes how rule‐based expert systems could be useful for signal processing tasks. Heuristic problem solving is introduced, which is followed by some fundamental aspects of conventional rule‐based systems and fuzzy expert systems. The design of a fuzzy expert system for a forecast problem is also illustrated.
Evolutionary Computation
Authors: Abraham Ajith
Published: August 2008

Evolutionary computation offers practical advantages to the researcher facing difficult optimization problems. These advantages are multifold, including the simplicity of the approach, its robust response to changing circumstance, its flexibility, and many other facets.

The evolutionary algorithm can be applied to problems where heuristic solutions are not available or generally lead to unsatisfactory results. As a result, evolutionary algorithms have recently received increased interest, particularly with regard to the manner in which they may be applied for practical problem solving.
Knowledge‐Based Systems
Authors: Hofmann Dietrich
Published: August 2008

An innovative paradigm in measurement engineering is the application of the knowledge‐based Web working between innovative enterprises, universities, and research organizations to support Internet metrology. The aim of the article is to discuss the new knowledge‐based methods, which are mature for application in everyday measurements and what they are able to do. A key feature is the new understanding concerning simple and complex measurements and the elaboration and standardization of not only metrological but also particular and objective virtual measuring standards. Practical examples for knowledge‐based legal metrology and knowledge‐based industrial metrology are given.
Quantizing Theory Relevant to
DAS
Authors: Wöstenkühler Gerd
Published: August 2008

Analog‐to‐digital (A/D) conversion in its basic conceptual form is a two‐step process:
quantizing
and
coding
. Quantizing is the process of transforming a continuous analog signal into a set of discrete output states. Coding is the process of assigning a digital code word to each of the output states. Some of the early A/D converters were appropriately called quantizing encoders. This article describes the quantizer of a data acquisition system (DAS).
Sampling Theory Relevant to
DAS
Authors: Wöstenkühler Gerd
Published: August 2008

An analog‐to‐digital (A/D) converter requires a small, but significant, amount of time to perform the quantizing and coding operations. The time required to make the conversion depends on several factors: the converter resolution, the conversion technique, and the speed of the components employed in the converter. The conversion speed required for a particular application depends on the time variation of the signal to be converted and on the accuracy desired.
Coding for Data Converters
Authors: Wöstenkühler Gerd
Published: August 2008

Data acquisition systems convert the analog value of signals into a digital representation which can only be realized with a step function. Each step is characterized with a unique binary combination. For further processing, the codes for all steps of the data converter have to be known. On the basis of the application and the amplitude range used, different codes are suitable. This article describes the commonly used codes in data acquisition systems.
Amplifiers and Filters for
DAS
Authors: Wöstenkühler Gerd
Published: August 2008

In data acquisition systems, the analog signals have to be adjusted to suit the amplitude range and sampling frequency needed by the converter employed. The analog signal, therefore, has to be conditioned with amplifiers and filters. This article gives an overview about different suitable amplifiers and filters used in data acquisition systems.
Digital‐to‐Analog (
D
/
A
) Converters
Authors: Wöstenkühler Gerd
Published: August 2008

Very elementary elements of data acquisition systems are digital‐to‐analog (D/A) converters. They convert a digital signal into a corresponding analog value and they are used to control the analog values of a process. This D/A function is also utilized in some analog‐to‐digital (A/D) converters (
see also
Analog‐to‐Digital (A/D) Converters
). This article describes some realizations and the typical behavior of some often used D/A circuits.
Analog‐to‐Digital (
A
/
D
) Converters
Authors: Wöstenkühler Gerd
Published: August 2008

Elementary components of a data acquisition system are analog‐to‐digital converters (ADC). Several different circuits have been developed. On the basis of the required speed, only a few types of the ADC are normally used. This article describes the nonintegrating types of ADC circuits used for medium‐ and high‐speed applications in contrast to the integrating types for low‐speed applications (
see also
Integrating Type A/D Converters
).
Integrating Type
A
/
D
Converters
Authors: Wöstenkühler Gerd
Published: August 2008

Elementary components of a data acquisition system are analog‐to‐digital converters (ADC). Several possible circuits have been developed. On the basis of the necessary speed only a few types of the ADC are typically used. This article describes the integrating types of ADC circuits for low‐speed applications in contrast to the nonintegrating types for medium and high‐speed applications (
see also
Analog‐to‐Digital (A/D) Converters
).
Analog Multiplexers
Authors: Wöstenkühler Gerd
Published: August 2008

A main task of a data acquisition system is the conversion of several analog input signals into their digital representations. A central component is the analog‐to‐digital converter (ADC). On the basis of the price of the ADC, it is recommended to multiplex one converter into several input signals. With this method, one ADC can convert 4, 8, or 16 analog channels using the time sharing principle.
Sample‐Hold Circuits
Authors: Wöstenkühler Gerd
Published: August 2008

A data acquisition system (DAS) converts between analog information and digital information. A sample‐hold circuit can be used to improve the uncertainty at analog‐to‐digital (A/D) conversion based on changes of the input voltage and the conversion time. Another application is its utilization as an output filter at digital‐to‐analog (D/A) conversion where it stores the analog information as long as it will be updated by the next converted value. This article describes some often used sample‐hold circuits and general characteristics.
Principles ofMEMSActuators
Authors: Bryzek Janusz
Published: August 2008

As the sophistication level of MEMS devices increased, the electromechanical systems on a chip started demanding equally sophisticated integrated on‐chip actuators. The first devices to include actuators were closed‐loop sensors to enhance the measurement accuracy. With time, complex mechanical systems on a chip were developed. Five basic control actuators were designed for MEMS devices: electrostatic, magnetic, piezoelectric, thermal, and optical. These are discussed.
Designing and Building Software for Measuring Systems
Authors: Kasser Joseph E.
Published: August 2008

Most measuring systems require a software system to support their operation and application. This article deals with setting up a software project element. It introduces the whole process by which a functional need is converted into a software program and discusses the steps and methods needed for sound development.
Smart Sensor System Features
Authors: Sydenham Peter H.
Published: August 2008

Smart sensors have been in use for some time, yet they still are not well defined in terms of what constitutes the smart aspect. This article discusses the basic ideas and implementations needed to develop and appreciate the conceptual design of truly smart, ‘fit and forget’ sensors.
Overview of Electrical and Electronic Technique
Authors: Sydenham Peter H.
Published: August 2008

An introduction to the nature and scope of electronic systems is given in the context of their place in measuring systems. After an account of the historical development, the systematic nature of electronic systems is explained. The literature of electronic systems is reviewed. The nature of signals in the electrical regime is covered.
Basic Electronic Components
Authors: Sydenham Peter H.
Published: August 2008

Electronic systems are built using a range of basic kinds of components. The nature of these is discussed, starting with conductors and insulators. Semiconductors are then covered. The differences between passive and active elements are explained. A large range of special parts are needed to complete electronic systems; these supplementary components complete this article.
Electronic System Building Blocks
Authors: Sydenham Peter H.
Published: August 2008

Moving down into the operational level of electronic systems leads to a description of the basic building blocks used to form analog and digital electronic systems. Linear units are first discussed leading to amplifiers. Digital systems are then covered starting with logic gates and then the various conditionally stable units. The features of digital systems are also described.
Electronic Systems Design
Authors: Sydenham Peter H.
Published: August 2008

Given that a basic set of building blocks exists for creating electronic systems, this article explains how they are used to build the more complex operations needed in measurement systems.
Limits of Detection in Electronic Systems
Authors: Sydenham Peter H.
Published: August 2008

Signal detection systems suffer from limiting conditions that are a physical outcome of the physics of their operation. This article provides an introduction to those limiting conditions existing in electronic components and systems.
Embedded Systems
Authors: Wilmshurst Timothy
Published: August 2008

Embedded Systems have wide application in the field of measurement and instrumentation, enabling as they do the automation of a measurement process, calculation of intermediate data and results, interface with other computer‐based systems, and data logging. The embedded system is generally designed around one or more microcomputers, usually taking the form of microcontrollers. Their design therefore incorporates, inter alia, aspects of hardware, software, interfacing, and data acquisition.
Principles of Fine Mechanics—Kinematic and Elastic Designs
Authors: Sydenham Peter H.
Published: August 2008

Many measurement systems require mechanical mechanisms in instrumentation. The fundamental purpose of the physical set up is to control motion. The importance of specifications and the problems that can arise are discussed. The two alternative design methods for creating fine mechanisms—kinematic and elastic—are introduced.
Kinematical Regime—Rotary Motion
Authors: Sydenham Peter H.
Published: August 2008

Kinematic design principles are used in the design of fine mechanical instrumentation. Within that class of mechanism, this material covers mechanisms that transfer rotary motion—couplings, gears, cams, and flexible drives.
Elastic Regime of Design—Design Principles
Authors: Sydenham Peter H.
Published: August 2008

Flexure elements deliberately make use of the elasticity of materials in the control of motion in fine mechanical systems. Their design basis is covered first, followed by descriptions of the various forms. An extensive literature listing is provided.
Error Sources in Fine Mechanics
Authors: Sydenham Peter H.
Published: August 2008

Despite the fact that many measurement solutions are now implemented in the electronic regime, there is still need for fine mechanical components that perform well. Their design knowledge reached a peak of interest around the 1950s. Since then, the topic of errors in fine mechanics has found little publication interest. This article provides an introduction to the errors and how to control them in the mechanical aspect of the design and application of measuring systems.
Principles of Fine Mechanics—Systems Considerations
Authors: Sydenham Peter H.
Published: August 2008

Mechanical parts of instruments need special attention for their design is different to that of electrical systems. This article covers the wear‐true principle and how to decide the best size for the instrument. The systems aspects of static and dynamics are introduced, leading to modeling mechanical systems.
Optical Materials
Authors: Chu Pak L.
Published: August 2008

Many measuring instruments make use of optical elements. This article deals with the basic materials commonly used to form optical elements, the building blocks of optical systems. (The term ‘optical’ is used frequently to describe the wavelength bandwidth including the outer bands of ultraviolet and infrared.) The basic glasses, abrasives for working glass, tools for shaping elements, and materials for holding elements during shaping, polishing, and cleaning are covered here. The properties of optical elements are outlined. Optical elements formed from these materials are covered in
Optical Elements
. Sources and detectors are discussed in
Light Sources and Detectors
. For the testing of optical systems,
see
Testing Optical and Other Radiation Systems
.
Optical Elements
Authors: Chu Pak L.
Published: August 2008

This article describes the basic optical elements encountered in optical systems. Emphasis is on the principle of operation of each kind of element. All topics are treated in terms of the ray theory of light, not the more comprehensive and complicated wave theory. Here, the optical fiber is treated as a light transmission component: coherent and incoherent fiber bundles are discussed. The GRIN lens, as an imaging device, is also included.
Light Sources and Detectors
Authors: Jonasz Miroslaw
Published: August 2008

A light source supplies radiative power whose spatial, temporal, and/or spectral distribution is modified by an optical instrument. The modified radiative power is then converted by a light detector into an electrical signal permitting further analog or digital processing. Basic parameters and key features of light sources and detectors are reviewed in this section.
Testing Optical and Other Radiation Systems
Authors: Cormier Alan J.
Published: August 2008

A wide range of optical instrumentation exists; however, the task of testing such instruments may in general be reduced to one of evaluating emitted wavefront form and image quality, where imaging is intended. Considered here are the test equipment commonly used to perform these tasks and the principles upon which key test methods are based, namely, interference, diffraction, and the optical transfer function. We also review typical limitations associated with the use of such test equipment and the need for regular calibration.
Uses and Benefits of
MEMS
Authors: Bryzek Janusz
Published: August 2008

MEMS technology dates back to the discovery of the piezoresistive effect in silicon at Bell Labs in early 1950s, as a by‐product of the semiconductor research. Though this technology evolved slower than the general semiconductor industry, as of 2004, several of its applications have created the expected multibillion‐dollar market. The forecast for the next decade points to many other applications based on MEMS technology that will grow by billions of dollars. This article characterizes key applications of MEMS devices in measurement and instrumentation applications.
Human Factors Engineering
Authors: Beagley Nicholas I.
Published: August 2008

The human is an essential component of most systems whether it is in the completion of a central function required for system success, or as a customer of a system's output. Human Factors provides the supporting science required to ensure the safe, effective, and efficient participation of people in achieving the objectives of a system. A wide range of methods have been developed to help researchers understand the capabilities of the human in conjunction with their tasks and environment in support of the design of efficient systems.
Human—Machine Interface
Authors: Beagley Nicholas I.
Published: August 2008

Interaction with our surroundings is an interactive loop in which sensory information is processed by our nervous system as the basis of actions in which we influence the world around us. Our ability to influence the world is enhanced by our ability, through human evolution, to develop tools. These mechanical devices are an extension of the physical world and we rely on the same cycle of sensory processing and control to direct the operation of machines. Human Factors is concerned with the interface between the human and the machine in the context of the intended task and associated environment. Recognition of the functional capabilities of the human senses and their translation into control actions is central to the appropriate design of suitable human–machine interfaces.
The Domains of Human Factors Integration
Authors: Beagley Nicholas I.
Published: August 2008

The true value of Human Factors lies in its ability to influence systems design for the better. Tools and techniques have been developed to support systems design to account for Human Factors issues. Adoption of these methods by systems design programs varies greatly. With consumer products, Human Factors tools are used to increase the chance of consumer acceptance and hence product success. In large‐scale government procurements, user acceptance is also one of the many considerations. Recognition of the importance of Human Factors Integration has led to the development of the US MANPRINT and the UK Human Factors Integration (HFI) defense procurement policies designed to ensure that these issues are raised and appropriately mitigated throughout the process of system procurement.
Design Methodology
Authors: Beagley Nicholas I.
Published: August 2008

To be successful in the design of human/systems, the design process must recognize a users inability to completely specify the precise details of a requirement at the start of a design program and the role of prototyping and iterative user testing for the refinement of a concept toward a design that is fit for a purpose. Several strategies exist to account for the capabilities of the user and variations within a target population. Techniques for exploring concepts at their earliest stage and for evaluating potential designs within a representative context offer a vital contribution to the challenges of human/system integration that face the designer.
Signals and Signal‐to‐Noise Ratio
Authors: Burdett Richard
Published: August 2008

In signal‐to‐noise ratio improvement, it is necessary to define the basic entities of signal and noise. This article does that and lists the commonly used methods for SNR improvement for the various kinds of commonly encountered signals.
Noise Matching and Preamplifier Selection
Authors: Burdett Richard
Published: August 2008

Setting up the input stage of a signal enhancement system is discussed in terms of transformer and amplifier designs. Models with various alternatives are provided. The effect of cable capacitance is covered.
Input Connections; Grounding and Shielding
Authors: Burdett Richard
Published: August 2008

The effect of the grounding of input stages of sensitive signal extraction systems is discussed in terms of ground loops. Reduction mechanisms that assist design input stages are provided.
Bandwidth Reduction of Baseband
DC
Signals
Authors: Burdett Richard
Published: August 2008

Where the wanted signal is at a low frequency, the noise present can be effectively reduced by limiting the bandwidth of the signal. This article uses the photomultiplier sensor as an example showing how bandwidth limiting operates. It also introduces the photomultiplier as the most effective detector of radiant energy.
Amplitude Modulated Signals: The Lock‐in Amplifier
Authors: Burdett Richard
Published: August 2008

By modulating signals that are accompanied by significant noise, it is possible to use synchronous detection to recover the signal. This gives a very narrow bandwidth, thereby significantly increasing the measured signal‐to‐noise ratio. This article deals with this detection method, as commonly implemented by an instrument called a
lock‐in amplifier
.
Grounding and Shielding
Authors: Fowler Kim R.
Published: August 2008

Grounding and shielding aids electromagnetic compatibility (EMC) by reducing or eliminating electromagnetic interference (EMI) between electronic circuits. Grounding and shielding applies to components, subsystems, or separate instruments. Grounding provides reference for signals and safety for people. This discussion assists determination of the paths of current flow in ground structures and the selection of the appropriate grounding scheme. Shielding reduces or eliminates EMI. It also covers sources of noise and mechanisms of noise coupling; these determine shielding and filtering needs.
EMC
and
EMI
Authors: Fowler Kim R.
Published: August 2008

Electromagnetic compatibility (EMC) and electromagnetic interference (EMI) deal with how electronic circuits interfere with one another. These interferences may exist between components, subsystems, or separate instruments. The discussion that follows provides the basis for EMC and EMI; these basic principles include: reciprocity, current follows the path of lowest impedance, diagnostic impedance, noise‐coupling mechanisms, electrostatic discharge, and diagnostic clues. These basic principles are then used in
Grounding and Shielding
, as a foundation for particular forms of grounding and shielding.
Boxcar and Signal Averagers
Authors: Burdett Richard
Published: August 2008

By averaging the repetitive signal with its noise, and if the signal is stationary in nature, then the noise being random tends toward zero. This is the averaging method of signal‐to‐noise ratio improvement that is described in this article.
Correlators in Signal Extraction
Authors: Burdett Richard
Published: August 2008

Correlation signal analysis is a method of detecting any similarity between two time‐varying signals. By matching the patterns of two sets of the same signal, it is possible to recover a signal buried in extraneous noise. The method of autocorrelation is also explained.
Photon Counting
Authors: Burdett Richard
Published: August 2008

One of the most sensitive detectors is the photomultiplier tube (PMT). This article introduces its concept, basic theory and application in low signal level detection.
Pulse Height Discrimination, Ratemeters and Pileup
Authors: Burdett Richard
Published: August 2008

In pulse counting systems, it is possible to separate out the different pulse heights, allowing signal extraction from a noisy situation. Related to this are the issues of pulse rate counting and pulse pileup effects with high‐intensity signals. This article discusses the use of photomultipliers to outline the elements of pulse height discrimination, rate counting, and pileup.
The Family of Signal Recovery Methods
Authors: Burdett Richard
Published: August 2008

There exist many methods for extracting detector signals buried in noise. A chart is present of the family of signal recovery methods. This chart assists selection of the appropriate method for a given application.
Types of Paper Standards and their Purpose
Authors: Eren Halit
Published: August 2008

Published standards play a fundamental role in shaping the efficiency of domestic and global economies. These statements, for measuring systems, provide textual and illustrative information on the ‘what’ and ‘how to’ of measurements. This article introduces the general form and nature, the methods of obtaining them, and their use in supporting the designs. A case study of the development of a standard is provided.
Internet Calibration
Authors: Dudley Richard A.
Published: August 2008

The Internet has changed the way we work from everyday electronic mail conversations to the remote monitoring of instrumentation in industrial environments. Combining Internet technology with specialist software and instrumentation has allowed the realization of Internet‐based calibration of measurement systems. This article explores some of the current systems, future possibilities, and drivers for their development.
Calibration Interval
Authors: Sydenham Peter H.
Published: August 2008

Calibration of measuring instruments is needed at appropriate intervals. This section deals with how to decide the calibration interval that is appropriate.
Accelerated Testing
Authors: O'Connor Patrick D. T.
Published: August 2008

This module explains the rationale of accelerated stress testing during development and manufacturing. It describes the methods used and the benefits that can be attained in product reliability and durability, costs, and timescale.
Automatic Test Systems
Authors: O'Connor Patrick D. T.
Published: August 2008

This module describes the uses and technologies (hardware, software) of an automated test. It also describes the applications of the automated test in modern engineering development, production, and service.
Test Facilities
Authors: O'Connor Patrick D. T.
Published: August 2008

This article provides a brief overview of the types of facilities that are available for testing materials, components, and systems.
Reliability and Maintainability
Authors: O'Connor Patrick D. T.
Published: August 2008

This article describes the concepts of reliability and maintainability. It includes the basic mathematical concepts, causes of failure, methods of design analysis, and test and data analysis. The related concepts of manufacturing quality and safety are discussed briefly.
Safety Organization
Authors: Sydenham Peter H.
Published: August 2008

An introduction to the general issues of safety of systems is provided. Safety and how the concept varies are defined. To create a background for appreciating the elements of safety planning, developing a sound safety culture and the responsibility for it is given. The roles of management and communication are covered.
Safety Analysis Methods
Authors: Sydenham Peter H.
Published: August 2008

Safety is very much a subjective system issue but analysis using formal thinking will assist improvement in a logical, modeled and recorded manner. This article defines basic definitions, outlines the relevant standards and safety assessment methods including Work Safety Assessment, Failure Mode and Effects Analysis, Failure Mode and Effects and Criticality Analysis, Fault Tree Analysis, and Hazard and Operability Analysis.
Assessing and Demonstrating Safety
Authors: Sydenham Peter H.
Published: August 2008

A suggested process for assessing system safety is explained. Its seven stages progressively analyze the level of risk, starting with hazard identification and ending with a demonstration of system safety on the basis of ALARP (as low as reasonably practical).
Kinematical Regime—Fasteners, Bearings
Authors: Sydenham Peter H.
Published: August 2008

Methods for holding two members together in fine mechanical instrument parts are called
fasteners
. Discussed here are permanent and detachable joints, and instrument bearings, also called
supports
or
pivots
.
Introduction to the Legal Process
Authors: Sweet Christopher
Published: August 2008

The sorts of legal issues that arise in measurement systems can be many and varied. This article provides an introduction to the issues involved and explains what to look for and how to reduce legal risk.
Testing Electronic Systems
Authors: O'Connor Patrick D. T.
Published: August 2008

This article describes the technologies (hardware, software) and methods for testing electronic systems (including components). It describes the applications of manual and automatic test equipment in modern electronic engineering development, production, and service.
Fuzzy Approaches for Measurement
Authors: Benoit Eric , Foulloy Laurent , Mauris Gilles
Published: August 2008

Since it appeared in Zadeh's (1965) seminal paper, fuzzy subsets theory has been effectively applied in many domains. This article presents the different approaches used in the measurement domain. It first defines fuzzy sensors as the application of fuzzy subset theory to measurement. Numerical and linguistic versions of fuzzy subsets for measurement are then presented before discussions of rule‐based fusion and interpolation fusion of information.
Scheduling Systems
Authors: Michta Emil
Published: August 2008

Application of the scheduling theory to the design of a distributed, real‐time networked measurement–control system is presented. Review of the priority‐based scheduling theory for the fixed priority assignment, system and task models, and application example are outlined. Emphasis is given to the processor and network utilization‐based test and to the task's worst‐case response time analysis. The same analysis approaches for task scheduling on single processor node and message scheduling across the network will be used. During the designing stage, scheduling of resources is decoupled and scheduling of each node and network is analyzed independently.
Electrical Bridge Circuits—Basic Information
Authors: Warsza Zygmunt L.
Published: August 2008

The principle of the voltage and current balance states of electrical circuits, applied in measurement is discussed. The Wheatstone bridge and a review of its 170‐year‐long history of development of different versions and their applications is presented. Bridge classifications are covered. A description of the bridge as a two‐port device represented by matrix
Z
parameters and their increments from the balance state is provided. This is a unified, universal, and useful tool for analysis of bridge properties and their two‐port application in various circuits of measurement systems.
Unbalanced
DC
Bridges
Authors: Warsza Zygmunt L.
Published: August 2008

Equivalent circuits for linear passive and reciprocal four‐terminal networks (4T) are developed. For a particular case, a detailed discussion is given on the resistance bridge working as the type X twoport of variable parameters. Relations of its impedance matrix elements as functions of bridge resistances in the balance state and of their increments are shown in Tables 1(a) and 1(b). The product of bridge terminal resistances completes the bridge balance condition. General linearity conditions of terminal parameters depending on large‐scale changes of arm resistances are formulated. Bridge output signals and terminal resistances of any mode of DC supply and load as functions of its

Z
R

matrixelements. Some properties and relations of the unbalanced DC bridge are presented below in a generalized and an original way.
Ultrasonic Instrumentation Principles
Authors: Lynnworth Lawrence C.
Published: August 2008

Ultrasonic principles are the basis for sensing solutions that work in many difficult applications. Early uses in the 1960s and 1970s did not always provide enough measurement performance to be practical in industrial processes. Today, system performance can be predicted by computer models and monitored with self‐testing diagnostics. Sophisticated constructions make use of microprocessor‐based electronic circuitry. Ultrasonic process control equipment is mature, robust, and metrologically acceptable, and is often the technology and product of choice that can be used in the harshest of environments.
Ultrasonic Instrumentation Design
Authors: Lynnworth Lawrence C.
Published: August 2008

Ultrasonic instrumentation design combines one or more electroacoustic transducers, means for making ultrasonic propagation and/or noise measurements, and means for interpreting such measurements so that the sought characteristic can be determined accurately, quickly, easily, and without significant interference from parameters other than the one of major interest. Ideally, one strives to make the measurement while disturbing the medium's boundaries or the medium itself as little as possible. Judicious choice of wave mode, frequency, coupling, path, and other parameters often leads to a satisfactory solution. But sometimes the medium or its enclosure, or other environmental restrictions, preclude obtaining a totally adequate solution. The present sensor and measurement examples are from industry (process control, NDT). Different, but sometimes analogous examples, may be found in the medical ultrasound literature. High‐power ultrasonics as used in cleaning, welding, and sonochemistry form a different part of ultrasonic instrumentation design and are beyond this section's scope.
Humans in the Real World
Authors: McGhee Joseph
Published: August 2008

Emphasizing the interrelation and interaction between humans and machines lays a firm foundation for proposing an overall model describing these aspects of measurement systems. It also allows an evaluation and comparison of the human sensing and machine sensing systems. A human and information machine model is proposed so that this crucial and central measurement link becomes clear. The two problems of measurement, namely direct and inferential measurement are described.
Organization of Instrument Science
Authors: McGhee Joseph
Published: August 2008

Instrument science is defined. This provides the justifying basis for considering ways in which it may be organized and systematized. The methods to be used in organizing instrument science, and particularly the orders of classification, are considered.
Substructure of Human–Machine Systems
Authors: McGhee Joseph
Published: August 2008

A boundary perspective of human–machine systems is described. It is shown that the main impact on these systems are resources, information, and contaminants or influence effects. This view is emphasized by a system model called an
information/energy tetrahedron
. Subsequently, it is shown that human–machine systems have a substructure consisting of a management system, a support system, a process system, and a measurement system.
Setting the System Boundaries
Authors: McGhee Joseph
Published: August 2008

The ‘whole‐life‐whole‐system’ approach of the systems engineering method is used to propose a boundary perspective of measurement systems. Extrinsic and intrinsic boundaries are proposed to separate impacts from outside a measurement system from internally arising effects. The important subdivision of measurement technology is used as a topical context to illustrate the application of the boundary view of measurement systems. Finally, the influences on a real system are described.
Hierarchical Aspects of Measurement Systems
Authors: McGhee Joseph
Published: August 2008

A measurement system can be considered as part of a systems hierarchy. Using a classification of the physical and life sciences allows the classification of measurement systems as one of the four information machines. The secondary functions of acquisition, communication, and distribution always supported by computation are described by functional features. Formal data measurement components in the form of analog, analog‐to‐digital, and digital elements are described and classified. A boundary view of the four information machines highlights the similarity between measuring, calculating, and communicating machines and the highlighting of the difference between them and the controlling machine.
Typical Measurement Systems Architectures
Authors: McGhee Joseph
Published: August 2008

A generalized architecture of a measurement system is given. Since microcontrollers/microprocessors/computers are widely applied, a typical structure of a microprocessor‐based instrumentation system with the various possibilities at the data acquisition end of these systems is considered. The importance of measuring instrumentation is emphasized through the descriptions of the typical instrumentation structures used in systems in diverse applications such as process control systems, petroleum/gas process systems and supervisory control and data acquisition systems.
Principles of Sensor Science
Authors: McGhee Joseph
Published: August 2008

The contributory disciplines of sensor science are briefly outlined. It is shown how systems engineering with its tools of reticulation and recursion play a central role in sensor science. Classification in sensor science is emphasized as a primary tool in the analysis of sensor systems as information machines for measurement. Brief outlines of holistic design, maintenance engineering, and sensor modeling are provided. The distinction between parametric and nonparametric models is described. The relevance of materials science, knowledge engineering, and artificial intelligence are highlighted.
Structure and Energy in Sensor Systems
Authors: McGhee Joseph
Published: August 2008

This article first describes the application of the systems engineering boundary perspective to sensor systems, which provides the basis for explaining the terminology and definitions for sensors and transducers as well as their representation using the energy/signal notation. Classification of sensors by information and energy is explained together with various schemes of energy classification. Spatial modeling of transducers is introduced and described for two‐dimensional and three‐dimensional representations. The three‐dimensional space used is called the
transducer space
. The article concludes with a description of the sensor effect tetrahedron and its application to modulating and self‐supporting cross‐converting sensors. The tetrahedron spatial model includes in its scheme of description the possible energy forms of contaminating/interfering sources. It is an important extension of the other spatial methods of modeling sensors.
Signal/Energy Matrix Modeling
Authors: McGhee Joseph
Published: August 2008

The signal conversion and energy flow in sensors and transducers can be modeled using the ideas of a signal/energy matrix. The principles of these models are described in this article using mercury in a glass thermometer and a digital thermometer. Case studies to illustrate the methods further deal with two different methods of shaft torque measurement and two different methods of level measurement.
Ideal Digital Filter Approximation
Authors: McGhee Joseph
Published: August 2008

Filters process signals to extract and enhance features. Originally, they were implemented in analog form, but now they are often built in a digital manner. This article covers the types of digital filter, their response in the time and frequency domains, and how they approximate the ideal case.
General Performance of the Digital Filter
Authors: McGhee Joseph
Published: August 2008

This article introduces the general characteristics of digital filters, how they are realized, the role of poles and zeros in design, and the impulse response of digital filters.
Low‐, High‐, and Band‐Pass Digital Filters
Authors: McGhee Joseph
Published: August 2008

The features and models of low, high, and band‐pass digital filters are discussed. Analyzing and building a digital band‐pass filter from a pole‐zero plot is outlined.
Finite Infinite Impulse Response (
IIR
) Digital Filters
Authors: McGhee Joseph
Published: August 2008

Continuing the explanation of digital filters, this article deals with the Infinite Impulse Response (IIR) form. These enable very selective passband filters to be designed.
Finite Impulse Response (
FIR
) Digital Filters
Authors: McGhee Joseph
Published: August 2008

Digital filters can take many forms. This article deals with the Finite Impulse Response (FIR) type covering the moving‐average form, the window method of design, and linear‐phase spectrum form. A summary of digital‐filter methods completes the article.
Fundamentals of the Stored Program Digital Computer
Authors: McGhee Joseph
Published: August 2008

The distinction between data and information is emphasized in the module. A common basic architecture for stored program computers is given and explained through its main elements. These consist of the central processing unit, its instruction set, and its memory. Primary and secondary memory is described. The basis of the fetch‐and‐execute sequential operation is described. Macroinstructions and their formats are explained.
Single Address Instruction Microcomputer
Authors: McGhee Joseph
Published: August 2008

The data width and address range of computer buses are considered and explained in this module. This allows computer instruction sets to be considered. Synchronous and asynchronous bus operation with their timing are described. Advantages and disadvantages are detailed.
Internal Operation of the Microprocessor
Authors: McGhee Joseph
Published: August 2008

The internal operation of microprocessors, which is fundamental to all stored program computers, is explained in this module. This operation is based upon FETCHING instructions from memory and EXECUTING them in a strictly timed sequential manner. Control state timing is described and illustrated using the Z80 op‐codes. Register‐to‐register transfer logic, which is the basis of the fetch/execute cycle, is considered in some detail using the notation now widely used in hardware description languages. Once again, the op‐codes of the Z80 processor are used to illustrate: (a) instruction fetch, (b) memory‐to‐register read, (c) write‐from‐a‐register, (d) arithmetic operations and (e) conditional microoperations.
External Operation of the Microprocessor
Authors: McGhee Joseph
Published: August 2008

In this module, the two types of input and output for a microprocessor, together with their programming, are considered. This concerns the requirements and means for effective data transfer. Interrupt generation and handling, using special signals, which are central to proper management of these processes, are shown to be preferable to polled input/output. This is especially true for (i) unsynchronized input/output (ii) randomly occurring input/output and (iii) multiprocessing cases. The various program requirements for the different kinds of interrupt processes including interrupt masking are described. Overcoming the speed limitations associated with processor controlled transfers requires the use of the direct memory access method, which is described.
Memory Management in the Microprocessor
Authors: McGhee Joseph
Published: August 2008

Memory management, one of the most important aspects of computer organization, is described in this module. It is based upon the principles of overlay management as used in microprocessors running under MSDOS. For more complex systems, especially where large programs are involved, it is necessary to use more sophisticated memory management techniques, which apply a combination of hardware and software approaches. All relevant approaches are described in the module. This includes word block transfers from primary to secondary memory, software replacement algorithms, and segmented systems. All of the techniques are described with the aid of suitable diagrams.
Data Acceleration in Computers
Authors: McGhee Joseph
Published: August 2008

To obtain the fastest operation from a given hardware it is useful to use some appropriate methods to accelerate data handling operations. Acceleration can be accomplished at the architectural level by using the methods described in the module. One of the most important techniques described uses cache memory to achieve acceleration because of its locality.

Operation of the cache is described together with memory fetch policies and the various cache mapping schemes.
Microcontroller Systems
Authors: McGhee Joseph
Published: August 2008

Single chip microprocessors are outlined so that microprocessor‐based data acquisition can be described in the module. It is then pointed out that microcontroller units contain all the functions of a microprocessor‐based data acquisition system on a single chip. The Motorola 68HC11A8, which is used as an example of an MCU, is described in some detail. The module continues by describing other special purpose digital processors including bit‐slice devices and elements. The AMD 2901 is used as the means of showing the typical structure of contemporary bit‐slice processors.
IEEE
‐488 Instrumentation Bus
Authors: McGhee Joseph
Published: August 2008

A detailed description of the IEEE‐488 bus is given. This includes information about the mechanical and electrical specifications, general bus format, controllers, talkers and listeners, and bus messages. Bus management and handshake protocols are also described.
Local Area (
LANs
) and Wide Area Networks (
WANs
)
Authors: McGhee Joseph
Published: August 2008

A basic description of local area networks is first given. Token passing and CSMA/CD approaches are introduced. Manufacturing automation protocol and ETHERNET are introduced. The two main standards, the IEEE 802.4 and the PROWAY are described and compared. Optical communication systems for use in LANs are described. Star, bus, and hub topologies are considered. Wide area networks are also introduced to show the outward use of local area networks.