bluuebunny/crossref_metadata_2025 huggingface dataset:
Flying primates: crashed, or crashed through?
Authors: Pettigrew John D
Published: November 2023

The flying primate hypothesis originated from the finding that megabats shared a number of advanced visual pathway characters with primates that were not found in any other mammalian order, nor in microbats. This hypothesis indicates that primates, colugos and megabats share a common ancestor with each other more recent than any shared with microbats. The hypothesis has found increasing support from other sources of evidence. Examples reviewed here include further derived brain features, both visual and non-visual, immunological studies of serum proteins with monoclonal antibodies and analysis of restriction sites and protein sequences (globins and cx-crystallin). DNA sequence data, while supporting the colugo-primate association, have been used to reject a primate-megabat connection, even though the total evidence for a colugo-megabat link is better than the generally accepted evidence for a colugo-primate link, and even though DNA sequence data and protein sequence data on the same genes give conflicting phylogenies. A resolution to this conflict is suggested by a bias in all the published DNA sequence data on bats. The shared substitutions claimed in support of bat monophyly are mostly of adenine (A) or thymine (T), in the same direction as the bias that exists in the overall base composition of DNA from metabolically-active, volant organisms. If the AT content of DNA is taken into account by using the NZ algorithm, the much-vaunted claims for bat monophyly based on DNA sequences are not supported. It is more parsimonious to assume that the AT bias responsible for the claimed association arose independently in the two lines of flying mammals.
MS/MS studies of tropane alkaloids: detection and determination of structure
Authors: Lawson* G , Ostah* N , Woolley† J G
Published: November 2023

Naturally occurring tropane alkaloids are a principal source of sympathomimetic amine drugs. Detection oftropane alkaloids in plant roots normally requires a lengthy extraction procedure followed by GC or GC-MS analysis (Robins et al. 1994). Alternatively, MS/MS techniques may be used as a fast analytical method for the determination of natural products (McClusky et al. 1978; Unger and Cooks 1979). This analysis, using MS/MS data from authentic compounds, means that tropane alkaloids in plant root samples can be identified without prior work-up, with consequent time saving and the use of much smaller sample sizes.
Lineage selection and transplantation of mouse ES cell-derived neural precursors
Authors: Schmandt Tanja , Glaser Tamara , Brüstle Oliver
Published: November 2023

Embryonic stem (ES) cells have become an indispensable experimental resource for studying cellular and molecular processes of cell differentiation under controlled conditions in vitro. Furthermore, their capacities to proliferate indefinitely and to differentiate into all somatic cell types make them a precious donor source for cell replacement strategies. The success of ES cell-based applications will critically depend on the availability of: (i) protocols for controlled in vitro differentiation; and (ii) assay systems for validating the functional performance of ES cell-derived somatic cells – the two key aspects covered in this chapter. The protocols described here are concerned specifically with mouse ES (mES) cells, which remain a paradigmatic model system for the development of novel differentiation strategies.
Lattice sums, the Madelung constant, and Paul Ewald
Authors: Templeton David H
Published: November 2023

Who was Paul Ewald? Several answers come to mind. Those who knew him as a person will think first of the man himself, whom they loved, respected, and admired. Then they will remember his scientific achievements or his leadership as a teacher, and editor and organizer of international crystallography. ‘The Ewald sphere’ may be the first response from many crystallographers if asked what they associate with his name. Those more familiar with his work will cite his dynamical theory of diffraction as his monument in science.
Multiple diffraction of X-rays and the phase problem
Authors: Colella R
Published: November 2023

In this chapter we will discuss a particular aspect of dynamical theory, namely, the use of multiple diffraction of X-rays in crystals for a solution of the phase problem. This subject, multiple Bragg scattering, a situation in which more than one set of crystallographic planes satisfy Bragg’s law simultaneously, was an area of diffraction theory in which Paul Ewald applied himself during the last years of his professional life.
Ideal Distributions
Authors: Shmueli Uri , Weiss George H
Published: November 2023

In our explicit calculation of the asymptotic form of the pdfs for the magnitude of the structure factor in space groups Pl and PI we showed that the characteristic function for the equal-atom case approaches a pure or modified Gaussian form when the number of atoms in the unit cell is large. In this section we show that the Gaussian limiting form is to be expected under more general circumstances than the equal-atom case for the two space groups analysed in Chapter 2. Indeed, the Gaussian limit is nearly always the starting point for investigations of both intensity statistics and direct methods in the crystallographic literature. In the mathematical literature the circle of ideas related to this Gaussian behaviour is known as the central limit theorem (e.g. Cramer 1946; Feller 1971). This theorem first appeared with specific reference to crystallographic applications in a paper by Wilson (1949). The results of this investigation are generally referred to as the ‘Wilson statistics’, and have had a great influence on the further development of crystallographic statistics including direct methods. Since the central limit theorem plays such an important role in crystallography it is useful to discuss some of the more elementary ideas behind this much used tool.
Fourier Representations of Pdfs in Direct Methods of Phase Determination
Authors: Shmueli Uri , Weiss George H
Published: November 2023

The role of probabilistic relationships in direct methods of phase determination has been of major importance in crystallographic practice during the past four decades. It has been documented in the crystallographic literature, mainly in Acta Crystallographica and in a number of books and monographs. The extension from pdfs of the magnitude of a single structure factor, of importance in intensity statistics, to the joint pdfs of several structure factors, on which direct methods of sign and phase determination are based was first discussed in the well-known monograph of Hauptman and Karle (1953b). A number of joint pdfs are further developed in the papers of Vand and Pepinsky (1953), Woolfson (1954), Cochran and Woolfson (1955) and Cochran (1955), and in many subsequent publications by Karle and Hauptman. An early and very clear exposition of corrections to Gaussian approximations of joint pdfs of several centrosymmetric structure factors was presented by Klug (1958) and both the centrosymmetric and non-centrosymmetric cases, using the Edgeworth expansion, are treated in two detailed papers by Naya, Nitta and Oda (1964,1965). Gaussian approximations to the joint pdfs of three structure factors were summarized by Woolfson (1961) and Karle and Karle (1966), who also proposed multisolution techniques that rendered the solution of the phase problem for crystals of small and medium-sized molecules a practical proposition.
The Fundamental Approach
Authors: McComb W D
Published: November 2023

Superficially the background material presented in this chapter may seem very similar to the topics covered in Chapter 1. That is, we begin with the Navier-Stokes equations and use the Reynolds averaging procedure to formulate the statistical approach. Then (just as in Chapter 1) we are concerned with the mean square excitation of fluctuations, with energy balances, and with the moment closure problem. We shall also consider the use of both dimensional methods and approximate models, and conclude by considering some representative experimental results. However, there will be two important differences of emphasis. First of all, our main interest will be in the underlying structure of the turbulence. That is, we shall consider the correlation of velocities at two or more points (and times). The foundations of this approach were laid by Taylor (1935) in a paper which also introduced the concepts of statistical homogeneity and isotropy: a step which took turbulence theory into the realm of physics, rather than engineering. In a subsequent paper (Taylor 1938a) the introduction of the energy spectrum in wavenumber (i.e. the Fourier transform of the two-point correlation in space) virtually completed this process, and, as we shall see, the calculation of this spectrum provides a major goal for fundamental turbulence theory.
Some Recent Developments In The Study Of Turbulence
Authors: McComb W D
Published: November 2023

This chapter is somewhat miscellaneous in character and is intended to serve two purposes. The first of these is to cover certain topics which would not easily fit into the main part of the book, yet which are important. The sections on anemometry, data processing, and engineering models are the main topics in this category. The second purpose is to try to give the reader a broad picture of what the rest of the book is about. That is, certain sections of this chapter should act as both an introduction to and an overview of more detailed and advanced treatments later in the book. For example, the section on renormalized perturbation methods is mainly descriptive, using only rather simple mathematics to explain the general method.
Numerical Simulation Of Turbulence
Authors: McComb W D
Published: November 2023

In recent times, the rapid growth in both size and speed of digital computers has tended to change our perception of the turbulence problem. Twenty or so years ago, the clear aim-shared by engineers and theorists alike-was to derive transport equations by averaging the Navier-Stokes equation. Nowadays, the possibility of computers becoming powerful enough to simulate some flows of engineering interest leads us to consider a simplified form of the turbulence problem: in broad terms, can we use fundamental approaches to reduce the number of degrees of freedom? That is, can we reduce the size of the task for numerical simulation? It is because we must now consider questions of this kind that we include here a short treatment of numerical simulation (in itself, a large and important subject) as a coda to our treatment of the statistical theory of turbulence. In doing this, we shall have three broad purposes in mind.
Coherent Structures
Authors: McComb W D
Published: November 2023

Organizing a logical account of a fashionable and fast-growing subject, like the study of coherent structures (or recognizable ‘deterministic’ patterns) in turbulent flows, is not without its difficulties. To begin with, quite a variety of such structures has now been identified, and, although different structures can appear to be very different phenomena, clearly they must all be facets of the same basic phenomenon, if only at the level that they are all solutions of the Navier-Stokes equation! At the present time, the safest way of tackling the problem of taxonomy, it seems to us, is to make a subdivision of the subject into very broad generic classes. For instance, a division into flows without solid boundaries--where coherent structure emerges rather easily as an organized vortex pattern-and flows with solid boundaries-where the coherent structure is not so easily seen, and requires a good deal of careful elucidation-seems likely to prove helpful, if only because such a division has tended to reflect different schools of activity.
In Situ Survey by Wave Propagation
Authors: Ishihara Kenji
Published: November 2023

When a body wave comes across an interface of two media with different stiffnesses, the direction of its propagation is deflected in accordance with Snell’s law as illustrated in Fig. 5.1. If the angle of incidence ψ1 is smaller than a critical angle ψc, the wave is refracted and propagates in the second medium with an angle ψ2 which is larger than ψ1 (where we have assumed that the wave travels faster in the second medium). If the incident wave encounters the interface with an angle larger than ψc, the wave is reflected into the first medium with the same angle ψR to the vertical, as illustrated in Fig. 5.2.
Strain Dependency of Modulus and Damping
Authors: Ishihara Kenji
Published: November 2023

It is well known that the deformation characteristics of soil are highly nonlinear and this is manifested in the shear modulus and damping ratio which vary significantly with the amplitude of shear strain under cyclic loading.
Effect of Loading Speed and Stiffness Degradation of Cohesive Soils
Authors: Ishihara Kenji
Published: November 2023

The tendency of soils to dilate or to contract during drained shear and pore water pressure changes during undrained shear does not come out in the infinitesimal or small strain ranges. The effect of the dilatancy begins to manifest itself as the magnitude of shear strain increases above the level of about 10-3 as indicated in Section 1.3. It should be remembered that the major changes in soil properties due to cyclic loading such as degradation in stiffness of saturated soils or hardening of dry and partially saturated soils can occur as a consequence of the dilatancy effect being manifested during cyclic loading. Thus the effect of load repetition as described in Section 1.2.2 begins to crop up when the strain induced in soils grow above the level of 10-3. This effect is alternatively called cyclic degradation.
Analysis of Liquefaction
Authors: Ishihara Kenji
Published: November 2023

The cyclic shear stress induced at any point within a level ground during an earthquake due to upward propagation of shear waves can be assessed by means of a simple procedure proposed by Seed and Idriss (1971). If a soil column to a depth z is assumed to move horizontally as shown in Fig. 2.4 and if the peak horizontal acceleration on the ground surface is amax, the maximum shear stress πmax acting at the bottom of the soil column is given by,
Heat Transfer By Conduction And Convection
Authors: Lawton B , Klingenberg G
Published: November 2023

Temperature is usually thought of as the degree of hotness of a material. When a spatial temperature difference occurs, heat flows from the hot region (heat source) to the cool region (heat sink) until the temperature difference is eliminated. The hot region loses energy and the cool region gains energy so it is useful to think of heat transfer as energy transfer by virtue of a temperature difference. This process does not occur instantly but requires a certain time, and so heat transfer is the study of the relationships between energy, temperature, spatial coordinates, time, and the properties of the materials involved.
Radiation And Radiation Transport
Authors: Lawton B , Klingenberg G
Published: November 2023

This chapter covers the fundamental definitions and laws of thermal radiation, elementary spectroscopy, radiation transport, absorption and scattering by particles. and radiation transport in the presence of scattering particles. [t is useful in defining the notation more closely hut may be omitted by readers who are already famili.ir with radiation theory. Its main value is, perhaps, to engineers whose first degree concentrates typically on radiation exchange between surfaces and often ignores the absorption, emission, and catering of radiation passing through a gap .
Large-Volume Anvils
Authors: Eremets M I
Published: November 2023

After consideration of the anvil system in general, we deal with particular anvil apparatus. Nowadays the diamond cell has become the most popular anvil apparatus. It will be considered separately (Chapter 3) and the rest of this book is devoted to a large extent to different applications of a DAC. However, a DAC has a significant drawback - a very small working volume. In this chapter, the anvil apparatus having a working volume orders of magnitude larger than for a DAC is considered. Complicated and cumbersome apparatus such as multianvil presses or ‘belt’ are not considered, because they are well documented and are not convenient for experimental applications. Instead, the main attention will be devoted to apparatus of the Bridgman type.
Pressure Measurement
Authors: Eremets M I
Published: November 2023

The pressure scale is well established only in the range to about 2.6 GP a where pressure is obviously defined as the ratio of load applied to a piston to the cross-sectional area of the piston. Different approaches to constructing an absolute pressure scale in the mega bar region are described in this chapter. Attention is mainly devoted to practical pressure scales, and in the first place the ruby scale. Features of pressure determination at low and high temperatures are discussed in the corresponding chapters. Examples of different pressure gauges for measurements under appropriate conditions are scattered through the book.
Brillouin Scattering
Authors: Eremets M I
Published: November 2023

Brillouin scattering is the inelastic interaction of light with acoustic phonons which results in a shift in the frequency of scattered radiation. This effect is similar to Raman scattering, but information is obtained abont acoustic branches of the phonon spectrum. Velocities of elastic waves, the complete set of elastic constants of materials, and much information in combination with other measurements can be obtained. An important feature of Brillouin scattering is the sensitivity to anisotropy of even cubic crystals where the dielectric constant is scalar and Raman and IR absorption are also isotropic. Selection rules allow always at least one mode to be observed, in contrast to Raman scattering and IR absorption, which fail, for example, in the case of rare-gas crystals. Brillouin scattering is one of the few techniques for obtaining some information about the phonon spectrum in these materials, as well as elastic and relaxation properties of viscoelastic liquids and amorphous materials.
Magnetic Studies Under Pressure
Authors: Eremets M I
Published: November 2023

Magnetism is an extensive field of solid-state physics. Here again, as in other fields, pressure is a powerful parameter, which allows the distance between magnetic moments to be changed and may cause a variety of magnetic transitions and other phenomena. A very effective method is to study the critical temperature and field of superconductors under pressure - Tc(P) and Hc(P) - to test different theories describing of superconductivity. Tc, in particular, can be determined by recording the change in magnetic moment due to repulsion of a magnetic flux in the superconductive state.
Technology of reactive ion etching
Authors: Handa S
Published: November 2023

The original meaning of ‘etching’ is ‘to eat’; the process of removing something from an object. Moreover, it is impressive that another original meaning of it is ‘to feed’. In fact, reactive ion etching (RIE) consists of two processes; ‘to eat’ and ‘to feed’. The physical process of etching is to remove particles from a solid surface by the colliding energy of ions which is converted into thermal, chemical, or kinetic energy. The mechanisms of etching can be classified by forms of energy exchange: chemical and physical. The etched pattern can be classified into two types: anisotropic (directional) etching and isotropic (indirectional) etching. When thermal and chemical energies are transformed in the reaction, then indirectional etching will be processed. Liquid chemical etching is a typical example of indirectional etching.
Introduction To Velocity Measurements
Authors: Bruun H H
Published: November 2023

To explain the concepts and principles of practical velocity measurements by hot-wire anemometry (HWA), consider the case of a hot-wire probe containing one or more sensors placed in a fluid flow. The purpose of the sensors is to provide information related to the velocity vector at the centre point of the hot-wire element(s). For the discussion contained in Chapters 3 to 6, the flow will be assumed to be isothermal and the density p will be assumed to be constant. The velocity field will be described by the velocity vector, V, at the point of the sensing element(s), where Vis a function of time for a turbulent flow. The direct output voltage from the anemometer is denoted by E, with indices of 1, 2, etc., in the case of a multi-sensor probe.
Numerical Techniques And Computer Applications
Authors: Guthrie R I L
Published: November 2023

Numerical methods for solving differential equations have become a very powerful weapon in the armoury of the practising engineer, following the widespread availability of high-speed digital computers since the early l 960s. Prior to that time, realistic solutions to commonplace engineering problems involving heat, mass, or momentum transfer were not easily obtained, except in those particular cases in which the boundary conditions were ‘well set’ and analytical solutions were available. Some of these, such as the error function solutions and series solutions have already been presented in preceding chapters.
Computation of 3-D Rotation
Authors: Kanatani Kenichi
Published: November 2023

This chapter focuses on 3-D rotations. A 3-D rotation is represented by a rotation matrix-an orthogonal matrix of determinant 1. We first review how a rotation matrix is expressed in terms of its axis and angle of rotation. Then, we discuss the problem of computing the rotation which best maps a given set of vectors to another set of vectors. This problem is analytically solved by three different methods—polar decomposition, singular value decomposition, and quaternion representation. These techniques are applied to two problems. One is orthogonality fitting—fitting three mutually orthogonal lines to three not necessarily orthogonal orientations. The other is orthogonal frame reconstruction-reconstructing an orthonormal system of vectors from its projection. This problem is formulated as a mapping from what we call a degenerate matrix to a rotation matrix. In order to solve this problem, we present a computational procedure called optimal resolution, which will play a crucial role in 3-D motion analysis (Chapter 6). Finally, we discuss numerical optimization techniques involving 3-D rotations.
Analysis of Optical Flow
Authors: Kanatani Kenichi
Published: November 2023

If the motion of objects (or the camera) is very small, the corresponding image motion defines an optical flow. Since the displacement of each image point is small (theoretically infinitesimal), it appears that computations based on optical flow are unstable and sensitively affected by image noise. However, the use of optical flow has the advantage that the flow is detected densely (usually at each pixel) over the entire frame by straightforward operations, whereas matching feature points over multiple frames for a finite motion is a very difficult task. Hence, it is expected that a reliable 3-D interpretation can be obtained from optical flow by optimization over the entire frame. As in the case of finite motion, we begin with planar surface motion and derive an analytical solution. Planar surface optical flow is easily determined by two methods—the flow-based approach and the contour-based approach. We then go on to general optical flow and present a robust analytical procedure. This procedure is almost identical to that for finite motion-all we need to solve is the epipolar equation written in terms of the essential parameters and the twisted optical flow. In order to ensure robustness in the presence of noise, the problem is also formulated in the form of optimization in two different ways. Finally, the critical surface that yields ambiguous 3-D interpretations is discussed.
Statistical Analysis of Geometric Computation, 2
Authors: Kanatani Kenichi
Published: November 2023

In this chapter, the techniques of statistical analysis established in Chapter 9 are applied to some of the most fundamental problems of machine vision. First, the reliability of focal length calibration is evaluated in statistical terms. We derive an optimal scheme for maximizing the reliability of the computed focal length and compute its confidence interval. Then, the error behaviours involved in 3-D motion estimation and conic fitting are analysed in detail. In each problem, the least-squares solution is shown to be statistically biased. We construct an unbiased estimation scheme and give numerical examples to demonstrate its effectiveness. Finally, a hypothesizing and testing approach is presented for making judgements concerning edge groupings, vanishing points, focuses of expansion, and vanishing lines. It is shown that the “credibility” of a given configuration can be computed by regarding “edges” as atomic elements and applying the X  2-test, which allows us to compare the credibilities of different configurations on the same basis.
d,q Modelling of Induction and Synchronous Machines
Authors: Novotny D W , Lipo T A
Published: November 2023

The induction motor is truly the workhorse of the industrial world. Until recently, however, they were limited only to driving loads which required nearly constant speed (or at best several discrete speeds) since the efficiency of the motor suffered drastically as the speed was lowered below the rated speed. With the advent of variable frequency power supplies this problem has been largely overcome. However, costs associated with the inverter have thus far prevented across the board replacement of de motors by ac induction motor drives. Analysis of induction machines is typically presented by means of the so called per phase equivalent circuit. However, this model proves inadequate when applied to dynamic conditions as encountered in a variable frequency drive.
Principles of Vector Control and Field Orientation
Authors: Novotny D W , Lipo T A
Published: November 2023

In this chapter the basic concepts of torque control and field orientation are introduced based on steady state considerations for both synchronous and induction machines. A basic set of three requirements which enable direct control of machine torque production is developed and used to illustrate the type of controller needed in both types of ac machines. These controllers are generally referred to as vector controllers because they control both the amplitude and phase of the ac excitation. The vector control of currents and voltages results in control of the spatial orientation of the electromagnetic fields in the machine and has led to the term field orientation [l,2,3]. Usually, this term is reserved for controllers which maintain a 90° spatial orientation between critical field components and hence we will adopt the term field angle control or simply angle control for systems which depart from the 90” orientation. The dynamic performance of the systems outlined in this chapter is considered in later chapters.
Effects of magnetic saturation
Authors: Vas Peter
Published: November 2023

In this chapter the effects of main flux saturation the equations required for the various implementations of vector control (e.g. rotor-flux-oriented control, magnetizing-flux-oriented control, stator-flux-oriented control) are discussed for both smooth-air-gap and salient-pole machines. However, only the derivation and a brief description of the required equations is given, since these can be applied similarly to the corresponding equations derived in Chapters 3 and 4, which, however, are only valid under linear magnetic conditions. It will be shown that as a result of saturation, the linear equations are modified and to obtain the required decoupling between the flux- and torque-producing currents of the machine under consideration, it is these equations which have to be considered when the machine operates under saturated conditions.
Artificial-intelligence-based steady-state and transient analysis of electrical machines and drives; Al-based estimators
Authors: Vas Peter
Published: November 2023

Traditionally mathematical-model-based analysis techniques have always been used for the steady-state and transient analysis of electrical machines. There are many techniques, but they mainly differ in their complexity and the many assumptions used. One of the most popular techniques relies on space-vector theory and is extensively used worldwide, and it is this technique which has also been extensively used in the present book for the development of various high performance, instantaneous torque-controlled drives.
Robust control techniques
Authors: Dote Yasuhiko , Hoft Richard G
Published: November 2023

Servo control is the technology for controlling position, speed, acceleration, and force in physical space and time. The servo-rigidity of a servo-motor driving system will be presented first (robust), and then the servo-rigidity considering mechanical errors will be described. The structure of servo-control theory is presented in Table 4.1.
Robust UPS control
Authors: Dote Yasuhiko , Hoft Richard G
Published: November 2023

This chapter describes a novel method of robust (i.e., insensitive to system parameter variations and load current changes) and fast digital control for an uninterruptible power supply (UPS) with a three-phase PWM inverter [8]. Here we have proposed a method by which characteristics better than those of conventional methods are obtained using a rather simpler algorithm. The adopted method has been proved by experiments and found to offer a total harmonic distortion of 0.62% of the output voltage waveform at the full nonlinear load. The analysis shows that the method exhibits sufficient stability. Three features of the method are: (a) a capacitor current observer and a disturbance observer for stabilization and robustness respectively are used to compensate the time lag by the computation and the disturbances in a minor loop of the capacitor current through an inductor-capacitor filter of the inverter; (b) new models of the inverter and the disturbances are established to simplify these observers; (c) the output voltage control loop can be designed easily and exactly because the minor loop realizes a rapid and robust control of the current.
DSP controllers
Authors: Dote Yasuhiko , Hoft Richard G
Published: November 2023

Most of this chapter is based on Dr. Slivinsky’s work [l]. Implementation issues are described by using the TMS32010; however, they are applicable to the TMS320C25. The recent rapid and revolutionary progress in microelectronics has made it possible to allow a control design using advanced control techniques (which has become a well-developed discipline during the last few decades) for the implementation of digital servo-motor control (DSMC). Microprocessors, such as the TMS320C25 digital signal processor, are increasingly being used to implement algorithms for the control of robust and optimal fast dynamic systems. The major factors contributing to this trend are the availability and lower costs of digital signal processors.
Summary
Authors: Dote Yasuhiko , Hoft Richard G
Published: November 2023

The main parts of this book are Chapters 5 and 6 where a robust AC drive control system and a robust UPS control system are described. These were practically designed, implemented, and tested, and are working well. The reasons the system works well in practice are as follows: By knowing the controlled objects well, suitable mathematical models are derived, which express the main system behavior. Robust and simple control algorithms are applied. Here, approximate zeroing control with an equivalent disturbance observer and prediction control described in Chapter 4 are utilized. Robust control systems are intensitive to external disturbances and parameter variations. Therefore controllers are easily tuned since practicing engineers do not have to identify system parameters. Simple control is essential not only for controller design engineers but also for practicing engineers, since it is understandable and low cost.
Diffraction Phenomena By Static And Dynamic Volume Gratings
Authors: Solymar L , Webb D J , Grunnet-Jepsen A
Published: November 2023

Diffraction gratings have a long and distinguished history. They have been used for a century and a half on account of their abilities to resolve the various spectral components of light. What are they? Any periodic structure will act as a diffraction grating. Up to quite recently they were produced mechanically by ruling grooves on a surface. Nowadays the holographic variety, produced by the interference of two waves, is more in vogue. Holographic gratings can also be divided into two big families: thin gratings and thick or volume gratings. A thin grating is produced for example by exposing and etching a photoresist. The aim there is to achieve a surface modulation. Our interest is in the other variety. Volume gratings, as the name implies, represent a periodic variation in some property of a chunk of material. Most often it is the dielectric constant which undergoes periodic variation. The technique of producing such a grating is illumination by an interference pattern followed by some processing. It needs to be mentioned how ever that not all volume gratings are man-made. Nature also provides them in the form of single-crystal materials in which the atoms follow a regular pattern. They diffract electromagnetic waves of rather short wavelength which are in the X-ray region. The discipline is known as X-ray crystallography.
How Light Influences Material Properties
Authors: Solymar L , Webb D J , Grunnet-Jepsen A
Published: November 2023

Our aim, as mentioned before, is to give a general overview of the whole field in this chapter, an overview which contains not only the basic physics but also the basic equations. We shall, of course, consider only those effects and those terms which are necessary for developing a ‘feel’ for photorefractive phenomena.
General Introduction
Authors: Solymar L , Webb D J , Grunnet-Jepsen A
Published: November 2023

The main aim in this Part is to provide a comprehensive coverage of the literature, describe the various models, offer experimental evidence, and try to describe the great variety of phenomena which belong to the photorefractive family.
A History Of The Photorefractive Effect
Authors: Solymar L , Webb D J , Grunnet-Jepsen A
Published: November 2023

A book written on a mature subject in the applied physical sciences should, by custom, have a historical review that should be objective, describe briefly and concisely all the major advances, name the people who made the advances, and, possibly, evaluate the state of the art.
The Field Equations For Two-Wave Mixing
Authors: Solymar L , Webb D J , Grunnet-Jepsen A
Published: November 2023

The field equations have already been introduced in Chapter 3 in a simple scalar form. It was hinted there that a more complex treatment is required in order to explain some of the more interesting phenomena observed in experiments on photorefractive materials; that treatment is the subject of this chapter. In addition to looking in more detail at the field equations, we shall also take the opportunity to review the comparisons that have been made between theoretical predictions and experimental results. This will help to differentiate between those situations where simple theory provides a good description and those where more effort is needed if quantitative agreement is required.
Six Topics In Search Of A Chapter
Authors: Solymar L , Webb D J , Grunnet-Jepsen A
Published: November 2023

In a well-organized book every topic finds a chapter. Unfortunately, this is not the case in the present one. However hard we have tried, some of the topics consistently refused to fit into any of the chapters written so far. The natural solution was to put these ‘anomalous’ topics into one chapter in spite of their diversity. Their common feature is that in some sense they depart from the norm.
Image Amplification And Image Processing
Authors: Solymar L , Webb D J , Grunnet-Jepsen A
Published: November 2023

First of all it is important to examine in general terms why there is interest in optical signal processing. The capacity of our electronic processing systems con tinues to increase at such a rate that the average scientist can have on their desk today a small PC with a processing power comparable to the departmental main frame of scarcely ten years ago. To date, this rapid increase in performance shows few signs of abating; nevertheless there are many signal processing applications where the speed of current electronic devices still leaves much to be desired. Typical are those applications where the data is in a parallel format such as an image and those where an operation is to be carried out simultaneously on a whole set of data.
Other Applications
Authors: Solymar L , Webb D J , Grunnet-Jepsen A
Published: November 2023

For reasons of space we have had to limit our coverage of the applications of photorefractives, and in the previous chapters we have tried to choose areas of activity that we feel are of continuing interest today. Nevertheless, there are a host of other applications that we have not yet touched upon and we hope to make amends for that here with a brief summary of other applications. The fact that we have relegated a subject to this section does not mean that it is somehow less worthy than the preceding chapters, or that these are applications that are less likely to be commercialized. Far from it, because the first topic concerns what is to our knowledge so far the only commercialized photorefractive product (excluding the crystals themselves, which can sometimes change hands for quite large sums of money!).
Effects Of Higher Order Terms
Authors: Hasegawa Akira , Kodama Yuji
Published: November 2023

In the application of solitons to a long-distance communication system, various higher order terms discussed in Chapter 3 become important, and one should study the effect of these terms on soliton solutions. The higher-order terms in the envelope equation derived in Chapter 3 are of the order of smaller than 10-4. Hence the effect of the higher-order terms on the transmission appears at distances longer than 104z0. For a soliton with a subpicosecond pulse, however, the relative spectral width c: becomes larger than 10-3, and the effect of higher-order terms can become important. We then employ the perturbation methods developed in Chapter 5 to analyse the NLS equation including the higher order terms which may be expressed as (5.2.1), i.e.
Introduction
Authors: Rothwell Charles A
Published: November 2023

From the point of view of computer implementations, object recognition was first studied by Roberts (106) in the early 1960s. Although the methods and the generality of the tasks have changed considerably since then, the goal is still the same: The goal of an object recognition system is to take either a single image or a sequence of images of a scene and determine both the identities and locations of objects that are present. Steadily, the aspirations of recognition researchers have developed so that now the objective is considered to be the ability to recognize three dimensional objects from an arbitrary three-dimensional viewpoint. Essentially, recognition can be formulated as a search problem and as such has to be guided in a controlled manner. This monograph investigates a number of the search issues.
Conclusions
Authors: Rothwell Charles A
Published: November 2023

This book has considered one approach to object recognition, that is, a breakdown of the process into selection, indexing and finally correspondence. In particular, we have studied the importance of using invariant indexes for the efficient hypothesizing of the presence of objects in scenes. The approach has centred around the LEWIS recognition architecture; two different implementations of the architecture have demonstrated that planar objects can be recognized efficiently using invariant indexing. This has, however, thrown open a number of issues that have been mentioned briefly through the course of this book, but in practice remain as issues for further research. These are considered in more detail in the following discussion.
Theory and practice
Authors: Woodward Philip
Published: November 2023

Early clocks which measured the burning of candles or the flow of water or sand had no chance of rivalling the accuracy to be obtained by counting vibrations. Without any natural rhythm, continuous flow is unlikely to remain constant to closer than about 1%, which is a quarter of an hour a day. The same might be said of the time taken for a child to slide down a banister rail at a speed dependent solely upon friction, which is surely the most variable of all mechanical forces. That eye-catching clock invented by Sir William Congreve, in which a ball rolls down a zig-zag groove in a tilted metal plate, works on much the same principle, though the friction is rolling rather than sliding. By contrast, the beat of a high quality resonator is virtually independent of friction, being determined by the interplay of two more stable qualities, inertia and elasticity. These are the fundamental characteristics that make all types of vibration possible, from a bowl of jelly to a quartz crystal.
Choosing an escapement
Authors: Woodward Philip
Published: November 2023

The number of different ways of maintaining a pendulum in oscillation is legion, and over the centuries many schemes have been tried - so many, indeed, that it would hardly be practicable even to list them, still less to place them in an order of merit, so I shall describe only those that are relevant to my story. First there are one or two matters of terminology. It is in the nature of mechanics that a pendulum should be maintained by a succession of little pushes rather than a continuous drive. A force acting through a given distance supplies a pulse of energy, known in mechanical horology as an impulse, which is unfortunate. To the academic mathematician, an impulse is defined as a force acting for a certain length of time, giving rise to a change of momentum, which is a different concept altogether. We must simply put up with this misuse of terms, which is hallowed by tradition.
Nonlinear Physics And Chaos
Authors: Lauterborn Werner , Parlitz Ulrich
Published: November 2023

To be sure, our description of nature is far from being complete. However, we are improving constantly in many directions, one of them being nonlinear physics. Indeed, we have learned that nonlinearity introduces a wealth of genuine phenomena. Among them, chaotic dynamics is the most puzzling and intriguing one. This type of irregular dynamics calls for new methods to cope with and has already set our for applications. The investigations on chaotic dynamics have shed new light on the notions of predictability and determinism - and their relation -, quite fundamental issues. The deterministic dynamics of even simple systems may be notoriously difficult to predict and even impossible in the long run. Such systems abound in nature, and examples can be drawn from almost any scientific discipline (see, for instance, [1-71]). This tutorial and review presents an overview of the achievements and some present research activities in the field of nonlinear dynamics. In particular, questions of embedding data into high-dimensional spaces, of modelling and prediction, noise reduction, detecting determinism in time series, and secure communication via chaotic synchronization are addressed.
Communications By Means Of Low Earth Orbiting Satellites
Authors: Pickholtz Raymond L
Published: November 2023

Many organizations have proposed satellite-based personal communications providing global coverage for voice and data to hand-held subscriber units with a direct link to a satellite. Such systems will offer the ultimate promise of personal communications of allowing communications to the personat any time and in any place, literally, rather than to a physical location.
Cosmic MASERS - A Powerful Tool For Astrophysics
Authors: Moran James M
Published: November 2023

Cosmic masers were discovered accidentally in 1965 by radio astronomers who were trying to map the distribution of gas in molecular clouds by measuring the absorption due to OH molecules against thermal background sources [Weaver et al., 1965, Gundermann, 1965]. The compelling argument for maser emission was that, although the spectral lines had linewidths appropriate for gas at -SO K, their equivalent blackbody brightness temperatures were very much higher.
Environmental radioactivity
Authors: Wilson P D
Published: November 2023

The world environment has always been radioactive, for most of its history probably more so than at present. Nevertheless human actions have redistributed part of that radioactivity and increased exposure to it, as one likely source of occupational hazard that was noted (though not diagnosed) as early as the sixteenth century, in the form of fatal lung cancers among miners.1 Most of the present concern about radioactivity however relates to the artificial component added since the mid-1940s, first from nuclear weapons and later from civil applications.
Management of safety
Authors: Fryer A C , Merry M , Sunman, C , Waterhouse A E
Published: November 2023

This definition emphasises that Safety Culture is about attitudes as well as management structures, policies, and directives. Statements of policy and managerial directives are of little effect if not supported by appropriate attitudes throughout the organisation. Safety Culture is therefore intangible, though it can (and does) lead to tangible effects. It is simpler to consider these two major components of Safety Culture separately, though recognising that they are intimately linked. External influences are also discussed.
Future perspectives
Authors: Wilson P D
Published: November 2023

Such questions have no clear-cut answer and will no doubt be debated for many years. This book however aims to provide some of the factual background, not the debate itself. Previous chapters have dealt chiefly with the current situation, which in many ways demands improvement to meet present difficulties or future challenges. Expectations of what is to come differ widely, but for the present let it be supposed that provision is required to maintain some form of nuclear power well into the next millennium; that fusion meanwhile remains technically or economically impracticable (as appears in fact very likely); and that fossil hydrocarbons can still be used as fuel, albeit to a diminishing extent and at generally increasing prices as they become scarcer.
Feathers for flight
Authors: Videler John J
Published: November 2023

Feathers are the hallmark of birds. Birds are unique among the flying groups of animals because the capacity to fly is exclusively based on the highly complex modified scales. Feathers come in various shapes and sizes and serve a multitude of functions. We are particularly interested in the structure and function of flight-related feathers.
Evolution of bird flight
Authors: Videler John J
Published: November 2023

Palaeontology is a difficult field of research. The ultimate goal is to discover the course of evolutionary processes using fossil evidence. This evidence is, by its nature, always circumstantial because experiments are impossible.
Bird flight modes
Authors: Videler John J
Published: November 2023

A bout of flight behaviour starts with the take-off event followed by a passage through the air over a certain distance and ends with a landing manoeuvre. By analysing repeated flights under controlled conditions the choice of flight strategies of a bird can be detected.
Posthumous Self-Portrait of Galileo Galilei, Philosopher
Authors: Frova Andrea , Marenzana Mariapiera , Mcmanus Jim
Published: November 2023

This self-portrait was never written by Galileo, of course, but it is what the authors of this book believe he would have sketched, had the times allowed him to express himself without formal respects and cautious attitudes. In compiling this autobiography, the authors have drawn widely upon letters written by Galileo and by his correspondents, as well as on biographies and documents of his time.