bluuebunny/crossref_metadata_2025 huggingface dataset:
Parameter Sensitivity and Saturation Effects in Indirect Field Orientation
Authors: Novotny D W , Lipo T A
Published: November 2023

The overall effect of this detuning is to incorrectly calculate the rotor field angle. In general, this causes the actual stator current components to be incorrect with the result that: (1) the flux level is not properly maintained, (2) the resulting steady state torque is not the commanded value, and (3) the torque response is not instantaneous.
The space-phasor model of a.c. machines
Authors: Vas Peter
Published: November 2023

As discussed in Chapter 1, the principles of the various forms of vector control and direct torque control of a.c. machines can be well understood by comparing the production of electromagnetic torque in d.c. and a.c. machines. However, for this purpose first the space phasors of various quantities (m.m.f.s, currents, flux linkages, etc.) will be introduced by utilizing physical and mathematical considerations. With the help of these, it is possible to formulate the space-phasor models of a.c. machines and to give a detailed explanation of the fundamental principles involved in vector-controlled and direct-torque-controlled machines.
Self-commissioning
Authors: Vas Peter
Published: November 2023

All the instantaneous torque-controlled drives (vector drives, direct-torque controlled drives) described in previous chapters use various machine parameters. On-line estimation of some of the machine parameters has been described in various sections, but in the present chapter different techniques are briefly described, which are suitable for the estimation of machine parameters by using simple tests prior to starting the drive system. It should be noted that a recent book (Vas 1993) discusses many types of parameter estimation and identification schemes. Furthermore, it is important to note that various modern industrial drives now incorporate self-commissioning techniques. In general, two main methods exist for self-commissioning: Self-commissioning without identification. In this case, no signals are measured and there are two main approaches. It is a great advantage that the computational effort is minimal, but it is a disadvantage that the parameters cannot be absolutely correct.
Intelligent Control Power Electronic Systems
Authors: Dote Yasuhiko , Hoft Richard G
Published: November 2023

This book describes intelligent control and its use in power electronic systems, specifically AC motor drives and uninterruptable power supply (UPS) systems. The book covers both the fundamentals of the subject and its practical applications. From the Foreword by Lotfi A. Zadeh, Director of Berkeley Soft Computing Center, California: ‘What is unusual about [this book] is that it starts with a description of more or less classical control techniques; moves on to modern control and state space techniques; addresses in detail the complex issues arising in the analysis and design of robust control; takes up digital signal processing controllers; and finally, presents a very insightful exposition of soft computing techniques and their application to advanced control of AC drives and UPS systems.’
Vector control
Authors: Dote Yasuhiko , Hoft Richard G
Published: November 2023

The origin of vector control dates from the 1970s with the work of Professor Leonhard [1] and his student Blaschke [2]. An earlier dissertation described work of a similar nature by Hasse [3] who was a student of Professor Joetten at TH Darmstadt. Originally the approach was referred to as ‘field oriented control’. However, in this text the term vector control is used, which is presently the most popular term, particularly in Japan where the greatest numbers of commercial products using this control technique were first produced. The vector control concept had its roots in very early work by Blondel [4], Doherty and Nickle [5], Park [6], and Kron [7]. During most of the past 25 years much additional work has been done [8–-14] which has greatly expanded our knowledge of vector control throughout the world.
Finite Element Methods in Electrical Power Engineering
Authors: Reece A B J , Preston T W
Published: November 2023

This book is designed to give the theoretical foundation needed by the new user of finite elements in electrical power engineering, and shows how the equipment designer can benefit from finite element analysis. It is divided into three parts; theory, modelling,and application of the finite element method. The first part outlines relevant electromagnetics, including treatment of boundaries, saturation and permanent magnets. It also shows how the finite element equations can be formulated. The presentation throughout is aimed at giving the reader a physical understanding of the process. The second part deals with special aspects of finite element modelling of engineering problems, including problem formulation, data generation and post processing and emphasises the importance of engineering judgement. The final part is an assembly of 'real' magnetic and electric field problems solved by finite elements, including application to turbine generators, permanent magnet machines, switched reluctance drives, induction motors, transformers and bushings.
Formulation of electromagnetic equations in finite element terms
Authors: Reece A B J , Preston T W
Published: November 2023

As its name implies, the finite element scheme transforms a problem of complicated form in a continuous region into one in which the region is discretised and an approximate (though good) solution is obtained for the field quantity at the discretised points (the nodes). The nodes are linked to form elements of the selected shape. It will be evident that by suitable choice of element shape complicated geometries can be represented well, and that, in principle, each element can have different properties: with incorporation of suitable solution algorithms, the properties can be non-linear. Thus a large set of algebraic equations has to be derived, in a way to be described, to replace the governing partial differential equation.
Treatment of non-linear materials
Authors: Reece A B J , Preston T W
Published: November 2023

Soft magnetic materials are those for which the width of the magnetisation loop is small and remanence can, to a first approximation, be neglected. Examples are the electrical sheet steels. Hard magnetic materials are those with a wide loop, operating in the second (or even third) quadrant and hence behaving as permanent magnets.
Derived quantities
Authors: Reece A B J , Preston T W
Published: November 2023

A quantity frequently needed by designers is the total electromagnetic force (or torque) on an object (e.g. an actuator armature or machine stator /rotor). Less frequently there may be a need for the force distribution acting on a coil or surface so that stresses on a component or the electromagnetically induced vibrational and acoustic behaviour of a device may be evaluated. Calculation of electromagnetic forces and particularly force distributions raises serious philosophical arguments as discussed, for example, by Carpenter (1959) and Carter (1962). These aspects wi11, as far as possible, be avoided here.
Post-processing
Authors: Reece A B J , Preston T W
Published: November 2023

It may be thought that the purpose of post-processing is self-evident: deriving whatever extra information is needed over and above that provided directly by the solution (usually potentials, energy and with some programs, additional quantities requested in the control data). However, it is worth reviewing some purposes which may be overlooked in the rush to get useable numerical data.
Selection of hardware
Authors: Reece A B J , Preston T W
Published: November 2023

Though hardware selection is not strictly an aspect of modelling, this chapter is provided because hardware, as well as software, influences what investigations are possible. The authors realise that they are entering dangerous ground in attempting to make any comment on selection of hardware and software for the fol1owing reasons:
Extensions for steady-state machine problems
Authors: Reece A B J , Preston T W
Published: November 2023

It will have been noted that the finite element equations are formulated in terms of applied scalar magnetic potentials or applied current densities. Thus when currents are known, the flux density distributions and flux linkages can be determined: in time-varying problems, the voltages induced in windings are also available. However, in the induction motor, for example, it is the applied voltage which is known, and the need is usually to compute the resulting currents and flux densities etc., for a given slip. With some approximations, discussed later, the rotor can be regarded as stationary, and slip dealt with by exciting the stator winding at slip fiequency, whilst calculating the induced voltage in the stator winding from the flux linkage and supply fiequency.
Time stepping for steady-state and transient problems
Authors: Reece A B J , Preston T W
Published: November 2023

The theory presented so far has dealt with magnetostatic conditions and cases where the excitation source (current or voltage) varies sinusoidally with time. It allows many problems to be tackled but there are deficiencies, even for steady-state cases. As pointed out in Section I 0.1, the assumption that voltage, current and field qmrntities all vary sinusoidally with time in a device with saturation implies that only a single value of permeability can be ascribed to each element, despite the variations of flux density throughout the time cycle. Additiona11y, second-order effects of motion are excluded.
Steady-state performance of large turbine generators: open circuit and load excitation and reactances
Authors: Reece A B J , Preston T W
Published: November 2023

Calculation of the open-circuit curve is, in principle, one of the simplest applications of the finite element method. There is no stator current and flux distributions and induced voltages can be calculated for the required range of field currents. In a large generator, three-dimensional effects are small and hence a two-dimensional model should give good results if approximate allowance is made for variations in the axial direction. As only fundamental frequency voltages are required, it is permissible to make calculations for a fixed rotor position relative to the stator slotting.
Turbine-generator transient parameters by simulated frequency response testing
Authors: Reece A B J , Preston T W
Published: November 2023

The Standstill Variable Frequency Injection Test which gives operational impedances as a function of stator frequency has been described in Section 10.4.1. A method of simulating this test using a two-dimensional finite element model has been outlined in Section 10.4.2 and the principles of modelling have been presented. The approximations necessary to allow a two-dimensional treatment and the question of rotor permeability are discussed there, as is the problem of discretisation appropriate to the wide frequency range of induced rotor current. This chapter takes the particular example of a 350 MW turbine generator and shows an approach which has been successful in predicting operational impedances and stator-field transfer functions. It compares calculated and test curves and briefly outlines how functional expressions can be derived for the impedances and hence how the various transient reactances and time constants may be derived.
Electric-field analysis in power transformers
Authors: Reece A B J , Preston T W
Published: November 2023

Chapter 20 gave examples of the use of the finite element method to determine the magnetic-field distribution in power transformers. However, magnetic design is only one aspect of the designer’s problem: a knowledge of the distribution and magnitude of the electric field is vitally important in producing a safe and economic design, and finite element analysis has an important role here. With transmission voltages up to 400 kV (r.m.s.) line and associated winding test voltages of 630 kV r.m.s. power frequency and 1425 kV pk lightning impulse the problems of configuring the high voltage (HV) winding, leads, stress control rings and bushings become apparent. On those rare occasions when something goes wrong, the consequences can be very serious. Figure 21. l indicates the severe damage that can be caused by a HV flashover, in this case between the corona shield at the coil end of the HV bushing and a neutral lead. The insulation on the lead has been severely ruptured under impulse test conditions and as a result a costly repair was needed.
Inverse Scattering Transform And N-Soliton Solutions
Authors: Hasegawa Akira , Kodama Yuji
Published: November 2023

In this chapter, we outline the method of inverse scattering transform (IST) for the nonlinear Schrodinger equation and its integrable higher order equation given in the form,

The term with c:/3, is the first integrable hierarchy of the NLS equation, and we call (4.0.1) the higher order nonlinear Schrodinger equation, the HNLS equation (Kodama 1985).

We then give the formula of the N-soliton solutions and their fundamental properties.

Before we discuss the IST method, we briefly summarize the well-known Fourier transform for solving the initial value problem of a linear equation. The reader will then find a similarity between these methods. In fact, the IST method is sometimes called the nonlinear Fourier transform.
Interaction Between Solitons In The Same Channel
Authors: Hasegawa Akira , Kodama Yuji
Published: November 2023

In order to increase the bit rate of a communication system, it is desirable to place solitons close to each other. However, because of the nonlinearity of the system, solitons mutually interact, leading to deterioration of the information-carrying capacity of the fibre. Chu and Desem (1983) showed that soliton interaction can lead to a significant reduction in the transmission rate by as much as tenfold. Blow and Doran (1983) showed that the inclusion of fibre loss leads to further increase of soliton interaction because of increased soliton width by the effect of loss. Georges and Favre (1991) also discussed an influence of amplifier noise-induced jitter on soliton interaction, and they found that the noise disturbs the soliton phase difference which modifies the soliton interaction.
Interaction Between Solitons In Different Channels
Authors: Hasegawa Akira , Kodama Yuji
Published: November 2023

In the previous chapter, we considered the interaction between solitons in the same channel where we assumed small (or zero) frequency differences between solitons, i.e. !AB! « 1 in (9.2.8). In this chapter, we first consider in Section 10.l interactions of solitons in different channels such as a case of the wavelength division multiplexing (WDM) with finite frequency separation. For an all-optical system, the WDM is well facilitated. However, in a soliton system with lumped amplifiers as discussed in Chapter 7, interaction of solitons between different channels may give rise to a change in frequencies of the solitons, and results in time displacements. This shift of soliton frequency is caused mainly in the following two processes.
Other Applications Of Optical Solitons
Authors: Hasegawa Akira , Kodama Yuji
Published: November 2023

In addition to its application to optical communication systems, the soliton phenomenon can be used for many other purposes. In this chapter we present some of these examples.
Spatial Solitons, Stability, And Chaos
Authors: Hasegawa Akira , Kodama Yuji
Published: November 2023

The concept of an envelope soliton was originally initiated by the discovery of self-focusing phenomena in a dielectric fibre (Chiao et al. 1964). However the generation and transmission of optical solitons have been so successful that the soliton concept has become much more popular than self-focusing. As a result the stably self-focused light beams are now often called spatial solitons.
Dark Solitons
Authors: Hasegawa Akira , Kodama Yuji
Published: November 2023

In the wavelength range shorter than the zero group dispersion point where k!’ is positive, the soliton solution does not exist. However, even in this range of wavelengths, the portion without light, which is produced by chopping a continuous light wave, is known to form a soliton. Such a soliton solution is often called a dark soliton. Dark solitons also appear in space called spatial dark solitons. Spatial dark solitons have interesting applications in the switching and guiding of light beams. We present here. the theoretical and experimental properties of a dark soliton both in time and space.
Time-Domain Electrodynamics of Continuous Media
Authors: Shyartsburg A B
Published: November 2023

This chapter is devoted to nonstationary propagation of nonsinusoidal electromagnetic fields in media with plasma-like dispersion, such as solid and gaseous plasmas, ionic crystals, and waveguide systems. The parameters of these media, widely used in optoelectronics and radiophysics, are considered here to be time-independent, whereas the propagating electromagnetic fields may possess significant nonstationary distortions due to dispersion and absorption. Unlike the usual approach associated with Fourier expansions of travelling plane waves and parameters of the medium, we shall operate directly, with time-domain Maxwell equations.
Time-Domain Optics of Transients in Dispersive and Absorbing Media
Authors: Shyartsburg A B
Published: November 2023

This chapter is devoted to an analysis of reflection, refraction and absorption phenomena in the processes of interaction of ultrashort arbitrarily shaped localized waveforms with dispersive and lossy media.
Plane Algebraic Projective Invariants
Authors: Rothwell Charles A
Published: November 2023

This chapter provides a sufficient level of theoretical background material in projective geometry and algebraic invariant theory for the understanding of the planar algebraic invariant shape descriptions used in LEWIS!. Algebraic invariants are just one example of how indexing functions can be computed for real shapes and so this chapter paves the way for Chapter 4 to achieve its goal, namely to prove by experiment that indexing is one of the key steps to producing an efficient recognition algorithm.
Projective Invariants of Smooth Plane Curves: LEWIS2
Authors: Rothwell Charles A
Published: November 2023

Invariants can also be computed for planar objects that contain more general plane curves than lines and conics. The subsequent discussion develops a process for forming invariant signatures for a class of smooth plane curves. These signatures provide a projectively invariant shape description from which indexes can be computed. Consequently, the process can be used within the LEWIS invariant indexing architecture for recognizing planar objects with boundaries consisting of higher-degree curves than lines or conics. The actual recognition system discussed in this chapter is called LEWIS2, and although a different system from LEWIS1, it shares many common processes.
Invariants for 3D Objects
Authors: Rothwell Charles A
Published: November 2023

So far we have been able to demonstrate that index-based recognition systems can be built around invariant shape descriptors. The previous chapters have been dedicated to proving this. The LEWIS architecture has been used successfully to recognize two different object classes using either algebraic invariants or a canonical frame construction. In fact, as a result of building the systems we were able in the last chapter to formulate a list of criteria that all shape descriptors should possess. Nevertheless, it should be borne in mind that the object classes used in the systems so far are very limited; it has been demonstrated only that planar objects can be recognized reliably. There is a real concern that the scope of the available invariant descriptors should be broadened.
Echoes of Hope-Jones
Authors: Woodward Philip
Published: November 2023

Froment’s escapement looked simple enough to make if only I could lay hands on an electromagnet. It occurred to me that my electric razor might contain something of the kind and on taking it apart I found just what was needed. It worked perfectly from a low voltage battery with only one drawback - the noise made as the armature snapped hard up against the iron core of the magnet every two seconds. I thought of trying to cushion this with something soft, but any such expedient would make the stroke an uncertain quantity. This would be as bad as a variable force and would invalidate the whole scheme, so the noise would have to be tolerated. Erroneously, I persuaded myself that we would all get used to it, even to the point of missing it when it stopped.
Harrison and congreve
Authors: Woodward Philip
Published: November 2023

My two electrical clocks had used ratchet wheels to measure out the intervals of one minute between impulses. Could not such a system be used in an all-mechanical clock? In ignorance of horological history I thought this a novel concept, though Congreve had patented such a clock in 1808 and found it a home in Buckingham Palace. I shall return to Congreve later in the chapter. A far more significant figure was John Harrison, now chiefly remembered for his practical proof that timepieces could work accurately enough to solve the problem of finding the longitude at sea. My particular interest was in his socalled grasshopper escapement, which had been invented in about 1722. I wanted to learn all I could from this. If the idea underlying so smooth and silent an escapement could somehow be adapted to infrequent impulsing, I might succeed in making a clock with jumping minutes and no clicks. That was my aim.
Going without gears
Authors: Woodward Philip
Published: November 2023

In response to a few turns of the winding key once a week, the escape wheel of an ordinary mechanical clock has to make at least ten thousand turns. That ratio, about a thousand to one, could be achieved with a single gear mesh by using a wheel 20 feet in diameter engaging with a quarter inch pinion, though none but an eccentric designer of sculptural skeleton clocks would consider such a possibility. It never ceases to surprise me that the same ratio can be achieved in three meshes using gears only 2.5 inches in diameter with three of the same quarter inch pinions. It is of course the multiplicative property of gear ratios that makes a cascade of gears so effective, and there is the added advantage that intermediate arbors can be made to turn at the correct speeds for driving hour and minute hands. In a traditional regulator clock this is just what happens; the second, minute and hour hands are all on arbors of the power train.
The phase circle
Authors: Woodward Philip
Published: November 2023

It is of little consequence that the sinusoidal driving forces discussed in the previous chapter are never encountered in mechanical clockwork. Any repeating pattern of force applied to a simple high Q resonator at or near its resonant frequency looks to it like a sinusoid; it can hardly tell the difference, and reacts just as it would to a sinusoid. This little known fact makes the calculation of escapement error in practical situations relatively straightforward.
Aiming too high
Authors: Woodward Philip
Published: November 2023

In the end it was to prove fortunate that my first attempt at a free pendulum ended in failure, for otherwise I would not have been spurred on to make W5. W4 was a compact wall clock, about the size of a Vienna regulator, but with two pendulums of different lengths swinging side by side. The shorter pendulum, a half-second slave, operated a pair of count wheels and took impulse every fifteen seconds. The longer one was the master, which swung freely for four minutes before receiving an impulse, during which time it had made 173 full vibrations. I took some pleasure in choosing that prime number, but almost any other number would have done equally well, for if there is no contact with the free pendulum between impulses, it can hardly matter how many swings it has made. Nothing in the mechanism depends on the particular number, though it must of course be an integer. The bob could be raised to give 174 vibrations in the four minutes and work equally well without any other adjustment. When details of W4 were prematurely published (Woodward 1974), an unwise step in any branch of research, the irrelevance of the master pendulum’s frequency did indeed puzzle some readers, though not for long.
ws
Authors: Woodward Philip
Published: November 2023

The Shortt clock was a product of the electromechanical age, which preceded the electronic revolution by a century. In 1920 the pendulum still held sway, but the electromagnet offered possibilities of control undreamed of in pure mechanics. Without such stimulus, the Shortt clock would never have evolved. However, with the benefit of hindsight, it struck me as an interesting challenge to see what might have been possible without making any use of electricity at all. The Shortt clock uses electricity to rewind the remontoire escapements of its free pendulum and its slave, which are both mechanical tasks.
Clockwork with a difference
Authors: Woodward Philip
Published: November 2023

The 1860s saw the appearance of two most unusual regulator clocks, one in New England and one in Scotland. Both clocks were new to me until recently, both were eye-openers and I can think of no more pleasant way to finish this book than by giving a brief description of each. Their inventors were William Bond of Messrs Bond and Son, Boston, Massachusetts, and Lord Kelvin (then Sir William Thomson) of the University of Glasgow. By the merest chance, only three clocks of each type were made.
How steam locomotives really work
Authors: Semmens P W B , Goldfinch A J
Published: November 2023

Steam locomotives were developed in the early part of the 19th Century, initially by Trevithick, and then most successfully by George Stephenson, whose engine Locomotion inaugurated the famous Stockton and Darlington Railway in 1825. For the next 150 years, steam locomotives were further developed and refined, until the advent of new electrical technology superseded them. Although British Railways operated its last main-line steam locomotives in 1968, there is still immense interest in the large numbers of locomotives which have been privately preserved, and which run on heritage railways and in various parts of the world. This book describes the anatomy and physiology of the steam train, to enable all train enthusiasts to understand the workings of the various types of engines in use. It covers the design of the engine, the process of converting fuel into mechanical tractive effort to haul passenger and freight trains, and the function and design of the various components of the engine. The authors also outline the reasons behind the safe and efficient operation and maintenance of steam locomotives. Although the steam locomotive originated in the UK, there were parallel lines of development in North America and in various other European countries, many of which introduced their own individual features. These are dealt with in the book, which will appeal to railway enthusiasts throughout the world.
Isotopic enrichment of uranium
Authors: Upson P C
Published: November 2023

Early interest was of course focused on enrichment to much higher levels, when isotope separation became a necessary and key stage of the development programme for nuclear weapons (the Manhattan project). Early in the Second World War, parallel development was carried out on several different processes, including gas centrifuges and gaseous diffusion, but also on other techniques such as electromagnetic separation, thermal diffusion and chemical processes. In fact, the electromagnetic method was used early in the US programme, but as it proved suitable only for very small throughputs, it has not been used commercially. It operates on the same principle as a mass spectrometer; a stream of uranium ions, passed through a transverse magnetic field, separates into different isotopes as the ions follow trajectories depending on their charge-to-mass ratio. The process is now used only for small quantities of special isotopes for medical or other research purposes.
Disposal of fuel or solid wastes
Authors: Richardson S , Curd, P , Kelly E J
Published: November 2023

Every industry produces waste, some of it highly dangerous. For example certain heavy metals and chlorinated hydrocarbons are toxic, remain so indefinitely, and need to be kept from the human environment effectively for ever. Although radioactive materials and the associated potential dangers are in principle different, decaying through time, the half-lives of some nuclides are so long that similar precautions may be needed. Others are short lived, or present in such low concentrations as to present little hazard, and precautions may then be relaxed accordingly.
Time Domain Wave-Splitting Green’S Function Approaches
Authors: He Sailing , Strom Staffan , Weston Vaughan H
Published: November 2023

The scattering kernels introduced in Chapter 1 and determined by means of the imbedding approach provide a framework for solving direct and inverse scattering problems, but the full wave propagation problem, i.e., including the determination of the field inside the scattering region, is not solved by the scattering kernels. However, during recent years the time domain wave-splitting approach has been extended to include the determination of the fields inside the inhomogeneous region. This extension, called the Green’s functions approach, is one of the main themes of the presentation in the rest of this book. The term Green’s functions refers to the regular parts of the split components of the fundamental solution. These regular parts are determined by the initial and boundary values of the propagation problem under consideration. Furthermore, the boundary values of the Green’s functions are related to the physical scattering kernels studied in Chapter 1, and thus a close connection with the imbedding approach is established. The system of equations for the Green’s functions is linear (and thus is one order faster to solve numerically than the non-linear imbedding equation for the reflection kernel), and is suitable for parallel processing. Thus it provides an approach to both direct and inverse scattering problems, which has some advantages as compared to the imbedding approach. In particular, in the three-dimensional case the Green’s function approach allows a simpler handling of the singularities (see Chapter 7).
Extensions Of The One-Dimensional Wave-Splitting Approaches
Authors: He Sailing , Strom Staffan , Weston Vaughan H
Published: November 2023

In this chapter, the one-dimensional wave-splitting approaches described in the previous two chapters are extended and applied to structures which lead to onedimensional problems such as propagation along non-uniform LCRG transmission lines, cases with obliquely incident plane waves, and propagation of plane electromagnetic waves in dispersive media.
Wave-Splittings Combined With Optimization Techniques
Authors: He Sailing , Strom Staffan , Weston Vaughan H
Published: November 2023

Recent developments and applications of various optimization methods have provided efficient tools for obtaining numerical solutions to various types of inverse problems (see, e.g. Frank and Balanis (1987), Kleinman and van den Berg (1990), Chew and Otto (1992), He and Kabanikhin (1995)). Optimization methods can be grouped into two types, namely, global search methods and gradient search methods. Global search methods include simulated annealing (see, e.g. Gamero et al. (1991)), neural network methods (see, e.g. Lu and Berryman (1990)), and genetic algorithms (see, e.g. Weile and Michielssen (1997)). A global search method is based on a stochastic algorithm, and its convergence can be very slow. A gradient search method is usually based on a deterministic algorithm, and it converges rapidly (though it may converge to a local minimum). In this chapter, wave-splittings are combined with gradient search optimization techniques. The procedure of deriving an explicit expression for the gradient of an objective functional through dual functions is described. The conjugate gradient method is used to reconstruct the line parameters, or spatial source distributions on a non-uniform line. The time domain inverse problem of reconstructing the temporal behaviours of a bi-isotropic slab is also considered, and a matrix formalism is introduced to derive an explicit expression for the gradient. A multi-dimensional acoustic inverse problem is also considered, and numerical reconstruction of a two-dimensional density profile is given. The Newton-Kantorovich procedure with a wave-splitting process is applied to a time domain inverse problem for a quasi-linear acoustic wave equation. Finally, a measurement system is described and the measurement data are used to reconstruct the susceptibility kernel of a polar liquid (1-buthanol).
Time-Harmonic Wave-Splitting Approaches
Authors: He Sailing , Strom Staffan , Weston Vaughan H
Published: November 2023

In the previous chapters we have treated time domain wave-splitting approaches and that is the main theme of the present book. However, the time domain results have their frequency domain counterparts, which can be obtained by means of a Fourier transform. One may also develop wave-splitting approaches directly in the frequency domain. The frequency domain treatments are of interest in them selves and they also serve to illustrate additional aspects of the time domain treatments. In view of this, several frequency domain wave-splitting techniques are described in this chapter. Besides direct and inverse scattering problems, some design problems will also be considered in this chapter. A design problem may also be formulated as an inverse problem, in which prescribed scattering data or patterns are used instead of measured scattering data. Relevant design problems are, for example, design of a wide-angled high-pass radome in a given frequency band, a frequency selective anti-reflection coating, etc. There are a few aspects in which a design problem differs from an inverse problem. In an inverse problem, measured (physical) data are used as given data. Usually at least one solution exists if the data are free of noise and the physical model is accurate enough. However, non-uniqueness of the solution can often not be excluded, and in many cases the inverse problem is ill-posed (which means in particular that noise-contaminated data may give an erroneous ‘reconstruction’). In a design problem, exact prescribed data are used, and thus the problems associated with noisy data do not appear. Non-uniqueness may still appear, but that means that several alternative designs are possible, and this is not a problem but rather an advantage. However, the existence of a solution may not be guaranteed in a design problem (in many cases one can only reach an optimal ‘solution’, instead of an exact solution). Another concern in a design problem is the feasibility of the solution obtained, from both a physical and a practical point of view (for instance, the specified data as well as the reconstructed parameters have to obey certain general conditions, which follow from, e.g. passivity and causality).
Three-Dimensional Wave-Splitting For The Scalar Wave And Telegraph Equations
Authors: He Sailing , Strom Staffan , Weston Vaughan H
Published: November 2023

In view of the results presented in Chapters 1–5, and obtained by application of different versions of the one-dimensional time domain wave-splitting approaches, an obvious question is whether these approaches can be extended to the corresponding three-dimensional problems. In Chapters 7 and 8 we present the current status concerning three-dimensional generalizations. The Green’s function approach is emphasized in these chapters. The imbedding approach in the time domain is not given because early investigation (Weston 1990) and subsequent work on the subject indicate that it is not a useful approach to apply in three dimensions.

It is inevitable that the mathematics of the presentation becomes more demanding. An effort is made to bring out, whenever possible and appropriate, analogies with the concepts, methods, and results from the one-dimensional case.
Wave-Splitting Of Maxwell’S Equations In Ir,3 And Applications
Authors: He Sailing , Strom Staffan , Weston Vaughan H
Published: November 2023

In Sections 8.3 and 8.4 the splitting is extended to a medium where ϵ = ϵ (x), μ = μ (x) and to a dispersive medium. For these cases the splitting is strictly mathematical. The splitting is applied to the inverse problem in Section 8.5. Finally in Section 8.6, non-planar wave-splitting is developed for Maxwell’s equations in free space, and the results are applied to obtain a non-planar absorbing boundary condition.
Dielectrics in static fields
Authors: Scaife B K P
Published: November 2023

For a fixed distribution of charges in free space Maxwell’s equations, eqn (1.85).the concept of a point charge is inconsistent with that of a charge distribution.
The implications of the nutrition transition for obesity in the developing world
Authors: Popkin Barry M
Published: November 2023

Dietary and physical activity patterns around the world have shifted at accelerated rates over the past decade. Rapid increases in the globalization of the food supply and food distribution networks, technology related to work and leisure, and the coverage of modern mass media are key global causal factors. Each of these global forces, along with urbanization and other shifts at the local level, underlie the quickening of the rate of change of diet and activity patterns of large subpopulation groups among most countries in the world. The resultant shifts in dietary patterns and away from energy-intense, market-oriented economic and home production-oriented work, travel, and leisure toward increased sedentarianism and lower overall physical activity levels have occurred concurrently.
Population approaches to increasing physical activity among children
and adults
Authors: Salmon Jo , King Abby C
Published: November 2023

Along with the evolution of the technological industry, the last 100 years have seen incredible transitions at the industrial, social, and cultural levels of society. Unlike our ancestors of long ago, however, our current adaptations to changes in our environment may not be as favorable to our survival as a species. Cars and machinery have reduced the need for physical labor both at home and in the workforce. Living in sprawling suburban housing developments that do not make it easy to walk, concerns about traffic and safety from personal crime, being time-poor, and a lack of individual confidence and motivation are all potential contributors to people being more likely to drive their cars rather than walk or bicycle to most destinations.
Population approaches to obesity prevention
Authors: Jeffery Robert W , Linde Jennifer A
Published: November 2023

The body of intervention research directed towards the modification of eating and physical activity behaviors in the population is quite substantial. However, considerably less research has specifically focused on population obesity prevention. The purpose of this chapter is to present a conceptualization of the causes of population obesity, to discuss the implications of this conceptualization for public health interventions, and to review empirical work that has attempted to address obesity treatment and/or prevention in entire populations.
The cost-effectiveness of obesity prevention
Authors: Carter Rob , Moodie Marj
Published: November 2023

The purpose of this chapter is to explore the economics of obesity prevention, particularly the available evidence on the cost-effectiveness of interventions and how the economic credentials for obesity prevention might be developed. The chapter begins with a discussion of the contribution that the discipline of economics can offer to an understanding of obesity prevention, explaining the separate but related tasks of description, prediction, and evaluation. Using these concepts, the chapter then explores what is known about the economics of obesity prevention. First, the depth and quality of the available economic literature on obesity is reviewed, and then Australia is used as a case study to illustrate the application of economic methods to describe the disease burden and to evaluate options for change.
Opportunities to prevent obesity in children within families: an ecological approach
Authors: Davison Kirsten Krahnstoever , Campbell Karen
Published: November 2023

Preventing the development of obesity among children is an international priority. This reflects the fact that rates of obesity among children have reached epidemic proportions in developed (1) and developing (2) countries, that obesity during childhood is associated with negative health and psychological outcomes (3), and that obese children tend to become obese adults (4). As outlined in Chapter 1, eating, physical inactivity, and sedentary behaviors (e.g. TV/video viewing, computer usage, video game playing) are established risk factors for the development of obesity among children and adults.
Drawing possible lessons for obesity prevention and control from the tobacco control experience
Authors: Mercer Shawna L , Khan Laura Kettel , Green Lawrence W , Rosenthal Abby C , Nathan Rose , Husten Corinne G , Dietz William H
Published: November 2023

While tobacco control experts in many developed countries announce remarkable reductions in tobacco consumption, nutrition and physical activity experts in these same countries bemoan the growing epidemic of obesity. Food and physical activity differ substantially from tobacco in that they are essential to life.Whereas the goal with tobacco control is therefore to eliminate all use, obesity control focuses on reducing some behaviors (excessive and unhealthful food intake) and increasing others (physical activity). Moreover, tobacco control involves preventing use of a single product while controlling food intake requires addressing a variety of products, and engaging in sufficient physical activity may require encouraging a range of activities and dedicating a period of time daily.
The potential for policy initiatives to address the obesity epidemic: a legal perspective from the United States
Authors: Fried Ellen J
Published: November 2023

In 2000, two prominent voices in the fields of public health and nutrition advocacy, Marion Nestle and Michael Jacobson, proposed measures to halt the obesity epidemic through the lens of public health policy (1).Halting the obesity epidemic: a public health policy approach chronicled a half century of US government recognition of obesity as a risk factor for chronic health conditions, yet revealed that governmental guidelines regarding diet, activity, and maintenance of healthy weight were both infrequent and, when offered at all, focused primarily on individual behaviors.Worse, the advice was typically banal and by all accounts, ineffective.
The potential of food regulation as a policy instrument for obesity prevention in developing countries
Authors: Lawrence Mark
Published: November 2023

The prevalence of obesity and its non-communicable disease (NCD) complications is increasing rapidly in many developing countries (1-8). Tragically, hunger, malnutrition, and food insecurity persist in developing countries. The coexistence of the acute diseases associated with undernutrition and NCDs associated with overnutrition has been described as the ‘double-burden’ of disease (9). The immediate cause of obesity is a dietary and physical activity behavior pattern resulting in energy intake exceeding energy expenditure. The underlying etiology of obesity is multifaceted, being embedded in environmental determinants rather than an individual’s behavior or genetic make up. The rise in the prevalence of obesity in developing countries is one indicator of the so-called ‘nutrition transition’ which itself is attributed to changes in socioeconomic, demographic, and political circumstances (10). The nutrition transition is characterized by shifts in food consumption patterns away from diets based on traditional indigenous foods towards diets comprising increasing amounts of high fat and energy dense, imported foods (11).
Avian Flight
Authors: Videler John J
Published: November 2023

Bird flight has always intrigued mankind. This book provides an up-to-date account of our existing knowledge on the subject, offering new insights and challenging some established views. A brief history of the science of flight introduces the basic physical principles governing aerial locomotion. This is followed by a treatment of flight-related functional morphology, concentrating on the difference in shape of the arm and hand part of the wings, on the structure and function of tails, and on the shape of the body. The anatomy and mechanical properties of feathers receive special attention. Aerodynamic principles used by birds are explained in theory by simply applying Newton’s laws, and in practice by showing the direction and velocity of the attached flow around an arm wing cross section and of the leading edge vortex flow above a hand wing. The Archaeopteryx fossils remain crucial in our understanding of the evolution of bird flight despite the recent discovery of a range of well-preserved ancient birds. Avian Flight offers a novel insight into the interactions between wings and air which challenges established theories relating to the origin of bird flight. Take-off, flapping flight, gliding and landing are the basic ingredients of bird flight, and birds use a variety of flight styles from hovering to soaring. Flight muscles are the engines that generate the force required to keep the wings and tail in the gliding configuration and perform work during flapping motion. The energy required to fly can be estimated or measured directly, and a comparison of the empirical results provides insights into the trend in metabolic costs of flight of birds varying in shape and mass from hummingbirds to albatrosses. The book will be of interest to biologists, ornithologists, and bird watchers. It will also be of relevance and use to physicists, mathematicians, and engineers involved with aerodynamics.
The bird flight engine
Authors: Videler John J
Published: November 2023

The functional anatomy and biomechanics of the flight apparatus is of great interest if one wants to know how birds fly. The internal proceedings form a challenging problem. A large group of scientists in the USA made a huge concerted effort to solve it during the last 15 years or so. Their names appear in the list of references related to this chapter.
The Origin of Nerves
Authors: Frova Andrea , Marenzana Mariapiera , Mcmanus Jim
Published: November 2023

An account of a demonstration of an anatomical dissection during which a philosopher, in order not to have his faith in Aristotle undermined, refuses to believe what a surgeon is showing him—namely, that nerves originate in the brain and not in the heart. This provides Galileo with the opportunity for an invective against knowledge based on dogma and tradition (ipse dixit), in which his fundamental ideas on the role and methodology of true science emerge.
Almost Free Fall
Authors: Frova Andrea , Marenzana Mariapiera , Mcmanus Jim
Published: November 2023

Using a piece of reductio ad absurdum reasoning which was to become a historical landmark, Galileo proves that, contrary to the Aristotelian conception, all freely falling bodies descend with the same velocity and take equal times to reach the ground. He describes the motion of such bodies as uniformly accelerated. Any divergences in behavior of bodies of different weight and shape falling in media other than a vacuum, he attributes to alterations caused by friction.