bluuebunny/crossref_metadata_2025 huggingface dataset:
Crises of the late devonian: the kellwasser and hangenberg events
Authors: Hallam A , Wignall P B
Published: November 2023

Between the Late Ordovician and the next great mass extinction in the Late Devonian the world’s marine fauna was afflicted by numerous lesser extinction events. Between them, Kaljo et al. (1996) and Walliser (1996) document over 24 bio-events in this interval. These minor extinctions are beyond the scope of this book but, by the Late Devonian the events were increasing in magnitude to such an extent that the crisis at the Frasnian-Famennian (F-F) boundary is widely regarded as one of the big five mass extinctions of the Phanerozoic. The subsequent end-Famennian or Devonian-Carboniferous (D-C) event has also been termed a mass extinction. The Devonian crises have been named by House (1985); the F-F and D-C examples were named the Kellwasser and Hangenberg events respectively, after characteristic black shale horizons in German sections. There are also grounds for considering an earlier mid-Givetian Taghanic event as a mass extinction.
Food and reproduction in the tropics
Authors: Simmons Robert E
Published: November 2023

A traditional view of both food resources and reproduction in tropical regions is that the environment is aseasonal, and food such as seeds, insects, or rodents do not peak and trough in the same boom and bust manner as found in the temperate climes. The aseasonal nature of tropical environments is certainly true, and as a northerner accustomed to long cold winters followed by a predictable burst of activity in the boreal spring, it came as a surprise to me to find a general lack of seasons in subtropical Africa. It was replaced by a cycle based on rainfall, not temperature. For example, large parts of Africa experience two distinct rain seasons each year, which are followed by a flush of resources as large as, and in the case of seeding plants and flying insects, often larger than, the flush of resources found in temperate regions.
Designing new habitats: general principles
Authors: Gilbert Oliver L , Anderson Penny
Published: November 2023

Long before seeds are sown or plants selected, successful habitat creation depends on the careful consideration of several basic factors. These factors can be grouped into several general topics. Site context is important and relates to the nature of the adjacent habitats and how the site functions in the wider ecological landscape. The next relevant consideration is the location of a site, how it is to be managed, and its potential use by people. Of critical concern are the nutrient status and nature of the soils or water in, or on, which the plants are to be established. Evaluation and analysis of these permits the selection of suitable objectives for the new habitat. Once objectives have been set, the design process has to consider questions of shape, scale, habitat type, species, and implementation (see Fig. 2.1). This chapter deals with these allimportant considerations.
The coast
Authors: Gilbert Oliver L , Anderson Penny
Published: November 2023

In a major habitat creation initiative English Nature has committed itself to trying to reverse the recent substantial and the predicted future loss of coastal habitats. As part of this strategy, a goal has been set to maintain coastal habitats equivalent to their distribution and total area in 1992 (English Nature 1992). This crisis is the consequence of centuries of ‘coastal squeeze’, which results from a combination of development or intensive agriculture pushing seawards (land claim) and the landward movement of the high-water mark due to erosion or rising sea level. Coastal protection schemes employing static structures (e.g. sea walls, groynes) also contribute to coastal squeeze by disrupting natural processes (e.g. longshore drift).
Getting it right
Authors: Gilbert Oliver L , Anderson Penny
Published: November 2023

We have constantly emphasized that habitat creation should never be regarded as a substitute for preserving the better semi-natural habitats. Its role is to improve our environment by helping to offset losses that have already occurred due to agriculture, urbanization, construction, and other destructive land uses. Despite criticism (Sutherland and Gibson 1988) habitat creation is an approach that is here to stay. Already it is central to government policies such as the Natural Areas Programme, Countryside Stewardship, Tir Cymen, Environmentally Sensitive Areas, and long-term set-aside, as well as being practised regularly by Local Authorities and landscaping firms.
Phylogenetic relationships of the pulmonate gastropods from rrna sequences, and tempo and age of the stylommatophoran radiation
Authors: Tillier Simon , Masselot Monique , Tillier Annie
Published: November 2023

As shown by the recent review of Bieler (1992), the phylogeny of opisthobranch and pulmonate gastropods is rather confused. Their fossil record is rather poor when compared with that of prosobranchs: some marine opisthobranch-like shells are known from the Carboniferous (Acteonina, Toumaisian, ca. 340 MY BP); but the first fossils, similar to members of the recent order Cephalaspidea, which may be attributed without doubt to the opisthobranchs are Upper Triassic, ca. 200 MY BP. From that time marine opisthobranch taxa regularly occur through the fossil record (Zilch, 1959-1960; Bandel, 1993). Similarly pulmonate gastropods, which include marine, freshwater and terrestrial taxa, have been supposed to have primitive terrestrial representatives in the Upper Carboniferous, ca. 320 MY BP, followed by a long gap until freshwater, marine and terrestrial forms appear in the fossil record in the Upper Jurassic, ca.
Malagasy Heron Ardea humbloti Milne-Edwards … Grandidier
Authors: Kushlan James A , Hancock James A
Published: November 2023

The Malagasy Heron is identified by its dark colour, black head and chin and very large, yellow bill. It is distinguished from the Grey Heron by its being larger, darker, with less contrast, and having a decidedly heavier bill. Interestingly, local people apparently do not distinguish between the two species although they do look quite different.
White-faced Heron Egretta novaehollandiae
Authors: Kushlan James A , Hancock James A
Published: November 2023

The Tricolored Heron is a medium egret that feeds in open shallow coastal waters for small fish. Its long bill and neck are a characteristic feature of fish-eating herons. Its wide repertoire of passive and active feeding behaviours allows it to find, run down if necessary, and capture these fish. Mangrove swamps, coastal lagoons, and other open shorelines provide feeding habitat. It is a surprisingly solitary bird, gathering in small groups when food is very abundant.
Capped Heron Pilherodius pileatus
Authors: Kushlan James A , Hancock James A
Published: November 2023

However, its ecology is rather distinctive, being sedentary and appearing to maintain family groups. Its calls and exuberant behaviour at the roost are unusual among herons. Furthermore, the prolonged dependence of young on adults is decidedly un- heron-like. Explanations may be the need to teach foraging, but such dependence in other species suggests a saturated habitat and maybe young birds face difficulty in establishing their own territory. Given the difference of this family life to that of most herons, the species is likely to also show unique demography and social structure.
Javan Pond-Heron Ardeola speciosa
Authors: Kushlan James A , Hancock James A
Published: November 2023

rice fields and other artificial habitats. The use of these are now likely critical to population stability. The loss of fish pond habitat led to a decrease of herons in Hong Kong (Young 1998). The management of occupied wetlands, including artificial environments occupied by the birds, is a critical conservation measure for the long-term stability of the populations. Eggs and birds are taken for food in China (Parish and Melville 1985). However, range expansion continues despite these losses. Hunting and other human use need to be evaluated.
Malagasy Pond-Heron Ardeola idea
Authors: Kushlan James A , Hancock James A
Published: November 2023

Walking slowly in shallow water or on the edge of the water. It feeds in the open, and is typically a bird of rice fields over much of its range. It is seen frequently and easily, and can be very numerous. It likely consumes a wider array of prey than is now known, and probably occupies a more diverse habitat. It is a successful species, benefitting from its association with agriculture.
Yellow-crowned Night-Heron Nyctinassa violaceus
Authors: Kushlan James A , Hancock James A
Published: November 2023

and success, and seasonal movements. Its breeding distribution needs to be understood in more precise detail. The Rufous-bellied Heron, like other Ardeola, appears to be a tropical reed bed heron. Many observations suggest that its habitat use is rather more complex though. It is a colonial nester, joining other herons in mixed colonies during the local high water period. It relies on quiet stalking techniques, as do the other pond herons. However, much more must be known to understand this species.
Japanese Night-Heron Gorsachius goisagi
Authors: Kushlan James A , Hancock James A
Published: November 2023

and irrigation systems. When rediscovered, the birds were in demand for the market in the area they are found, and their rarity did not provided much protection. The only hope for the species is for its welfare to become a concern of the local human population, its nesting sites be completely protected from disturbance, and feeding sites secured. The only successful conservation for this species will be that provided by and in cooperation with the local people.
Australasian Bittern Botaurus poiciloptilus
Authors: Kushlan James A , Hancock James A
Published: November 2023

population is even more at threat, given its rapid decline over the past several decades. Conservation action in its remaining known locations in South Africa and Zambia is essential. There have been important advances in our under- standing of the biology and conservation needs of this species. Studies should continue on the breeding, habitat needs, and demography of this species especially outside western Europe, where most information is from. Surveys are needed to determine the status and distribution of nesting of Eurasian Bitterns in southern Africa and wintering birds in northern Africa.
Streaked Bittern Ixobrychus involucris
Authors: Kushlan James A , Hancock James A
Published: November 2023

but overall has a broad diet of whatever it can encounter in the marsh. It has the potential for being adaptable in that its favoured habitat is also one that responds well to human hydrological alteration and it is able to use more open and even human-created habitats. It none the less occurs primarily in inaccessible situations, and its biology remains very much unknown.
Least Bittern Ixobrychus exilis
Authors: Kushlan James A , Hancock James A
Published: November 2023

Other names: Nitlin, Gaulin in English; Avetorillo Panamericano, Garcilla, Garcita, Martinetito, Mira- sol Menudo, Gallito, Alcaravancito, Garza Enana, Ardeola in Spanish; Socoívermelho in Portuguese; Petit blongios, Blongios minute, Kio jaune, Crabier, Mang lanmé, Martinet in French; Amerikanische Zwergdommel in German. Subspecies: Ixobrychus exilis erythromelas Vieillot, 1817: Paraguay; Ixobrychus exilis bogotensis Chap- man, 1914: Suba marshes, Bogota, Colombia; Ixobrychus exilis pullus van Rossem, 1930: Tobari Bay, Sonora, Mexico; Ixobrychus exilis peruvianus Bond, 1955: Vegueta, Lima, Peru.
Little Bittern Ixobrychus minutus
Authors: Kushlan James A , Hancock James A
Published: November 2023

wave action, abandonment, and predation, including mink (Mustela), wrens (Cistothorus), snakes, raccoons (Procyon), crows (Corvis), turtles, and raptors. Nothing is known about the population biology or demography of this species. Conservation of this species requires protection and management of its marsh habitat. Water impoundments and wetland construction for various purposes increase the potential habitat for the species as it often nests in cattail marshes created by human activities (Post 1998, Gibbs et al. 1992a, Horstman et al. 1998).
Yellow Bittern Ixobrychus sinensis
Authors: Kushlan James A , Hancock James A
Published: November 2023

The Australian population is considered to be uncommon, but rather appears to be concentrated seasonally in a few highly suitable breeding sites. It has declined and had to shift its distribution due to past hydrological changes in its rivers (Maddock 2000). It is classified as Endangered in Victoria (NRE 2000), where it represents only 0.7% of bird observations in the state since 1970 (Scientific Advisory Committee 1997). Management and conservation of these river systems are critical to the species in Australia.
Cinnamon Bittern Ixobrychus cinnamomeus
Authors: Kushlan James A , Hancock James A
Published: November 2023

China. Mostly there is little information available. It is considered to be in the Category Data Deficient by HSG (Hafner et al. 2000). The principal conservation need for this species is for clarification of the breeding distribution and the identification of potentially important areas for their protection. Surveys of known and potential breeding sites should be undertaken and reported, especially in east Russia and east and south China (Hafner et al. 2000). So little is known about the biology of this species that studies of its basic biology are urgently needed.
The theoretical basis of NMR
Authors: Gadian David G
Published: November 2023

In order to understand how radiation is absorbed by matter, we need to recognize firstly that radiation is quantized and secondly that atoms and molecules can only have certain discrete energy levels. These are concepts that are outside the realm of classical physics, and therefore a rigorous treatment of any spectroscopic technique requires the use of the branch of physics that is termed quantum mechanics. However, certain aspects of NMR can be understood surprisingly adequately and clearly in terms of classical physics. For this reason descriptions of NMR theory frequently contain a mixture of quantum mechanical and classical treatments, depending on which provides the simpler or more helpful picture of what is happening. In this chapter, we shall first give a brief quantum mechanical description of the basic properties of atomic nuclei, explaining how magnetic nuclei interact with applied magnetic fields. The treatment that is presented here is intended to be comprehensible to readers with no prior knowledge of quantum mechanics; however, some of the results that are given will have to be taken on trust, for the theory on which they are based is beyond the scope of a book of this type. We shall then proceed to describe NMR in terms of the classical model that is particularly well suited to explaining many of the practical aspects of NMR, such as the effects of radiofrequency pulses. The latter part of the chapter is concerned with the Fourier transform, which plays a critical role in NMR imaging and spectroscopy.
Instrument design and operation
Authors: Gadian David G
Published: November 2023

In this chapter we discuss each of these units and the ways in which they interact with each other. In addition, an explanation is given of some of the common operational procedures that are involved in obtaining images or spectra. For simplicity, many of the procedures are introduced in terms of the acquisition of spectra. However, we have seen that imaging and spectroscopy have many features in common; both NMR approaches involve the collection and display of signals as a function of frequency, the main technical difference being that in spectroscopy the frequency encodes for chemistry, whereas in imaging the use of linear field gradients causes the frequency to encode for space. Therefore most of the procedures that are described are equally applicable to the acquisition of images.
Lattice-dynamical interpretation of crystallographic thermal parameters
Authors: Gramaccioli Carlo M
Published: November 2023

In usual crystallographic calculations, the effect of atomic motion on the structure factor FH is considered in the so-called temperature factor , τj(H):where H is a reciprocal-lattice vector, denoting a reflection, and rj a directlattice vector, denoting the position of thej-th atom. The temperature factor is the Fourier transform of the probability density function (pdf) of an atom around its mean position. If the pdf is isotropic and the distribution Gaussian, then (see Chapter 6, Section 6.7, and Chapter 8, Section 8.2):Such isotropic temperature factors were used in early crystal structure determinations. Here the most critical approximation is the assumption that the pdf is the same in all directions. This is actually the case for some of the simplest structures, where the atoms are located in special positions of high symmetry, and which were the first to be determined (for instance, NaCl-type compounds, or simple metals, oxides, etc.). However, already in the first electron-density maps of structures where atoms are not in highly symmetrical positions, the peaks typically appeared as flat or elongated, suggesting strongly anisotropic thermal motion.
Structural substituent effects in benzene derivatives
Authors: Domenicano Aldo
Published: November 2023

The purpose of this chapter is to show how the availability of accurate geometrical information on a class of related molecules − the substituted derivatives of benzene − has fostered new lines of structural research. It would have been possible to select some other example, but this one has at least two merits. First, it refers to a fundamental class of organic molecules; second, it involves important contributions from most of the techniques of structure determination described in this book. †Substituting a hydrogen atom with a functional group causes a perturbation in the valence electron distribution of a molecule. This affects a number of chemical and physical properties. Changes occur in, e.g. reaction rates, equilibrium constants, dipole moment, spectral parameters, and, last but not least, molecular geometry.
Radiation used in crystallography
Authors: Aslanov L A , Fetisov G V
Published: November 2023

The radiation generally used in diffraction experiments and referred to as X-rays consists of electromagnetic radiation having wavelengths of between 0.7 and 2.3 angstrom. Such electromagnetic waves are called gamma-rays if they are emitted by radioactive materials and X-rays if they are generated by accelerated (or retarded) charged particles. According to the laws of electrodynamics, a charge moving with acceleration (or retardation) must generate electromagnetic waves. In practice, electromagnetic radiation with the wavelength of X-rays is usually both generated by accelerated (or retarded) electrons driven at high speed and due to the radioactive decay of atoms.
Auxiliary methods
Authors: Aslanov L A , Fetisov G V
Published: November 2023

Both single-crystal and powder X-ray crystallography use a number of auxiliary methods for crystal structure determination under abnormal conditions, such as low and high temperature, high pressure, external field action (e.g. electric field, magnetic field, laser irradiation etc.) and a combination of all sorts of external influences to investigate their impact on crystal structures and charge densities. Sometimes low-temperature measurements are used for reducing the crystal lattice vibrations to avoid ambiguity of the charge density maps and disorder of the atomic positions or for increasing resolution of crystal structure analyses. Auxiliary methods also allow experimenters to investigate crystals under conditions similar to those existing in technical devices (electronics, optical instruments, etc.) where the materials are used and to find out the relationship between the crystal structure and its properties under operating conditions.
Flow Boiling: Onset of Nucleation and Heat Transfer
Authors: Whalley P B
Published: November 2023

From Fig. 16.2 it can be seen that there is a large increase in wall temperature when dry out occurs: this increase may be many hundreds of degrees. Also, before dry out occurs the difference between wall temperature and the saturation temperature is gradually decreasing. Therefore, the boiling heat transfer coefficient is increasing; this is a consequence of the liquid film in annular flow becoming thinner as the quality increases. One convenient way of expressing the heat transfer coefficient variation along the tube is to plot it against the thermodynamic quality, as in Fig. 16.3. In this figure, lines 1, 2, and 3 represent different heat fluxes. At the highest heat flux, curve 1, burnout occurs before is equal to zero. At a lower heat flux, curve 2, burnout occurs after xT = 0. In the region of positive quality nucleate boiling occurs, and this ceases at burnout. At the lowest heat flux, curve 3, there are five distinct regions.
The Planar Serial Robot-arm
Authors: Davidson Joseph K , Hunt Kenneth H
Published: November 2023

A robot can broadly be described as a versatile and programmable machine for controlled manipulation of objects. Its end-effector, namely the member most remote from the base-frame, is partly a tool that may take many forms, for instance that of a gripper, a welding device, or a routing cutter. Several writers, for example, Craig (1989) and Rosheim (1989), take end-effector as the generic name for the tool itself that is attached to a tool-plate of a robot; yet the entire assembly that comprises tool-plate and tool is not necessarily excluded from the meaning. In this book we identify end-effector with the rigid body that carries the tool, a meaning that is implied by the above writers and is consistent with other sources, for example, Huang and Waldron (1989) and Agrawal and Roth (1992).
Describing the Screw
Authors: Davidson Joseph K , Hunt Kenneth H
Published: November 2023

We defer until Chapter 3 the full analytical treatment of the screw. In this section the reader is introduced to the role of the screw in mechanics. In introducing the screw we start with static equilibrium, and then, in §2.1.2, we develop the kinematic analogy.
Spatial Serial Robot-arms
Authors: Davidson Joseph K , Hunt Kenneth H
Published: November 2023

The purpose of this chapter is to discuss the instantaneous kinematics, workspace, and driving-force requirements for spatial six-actuator (and five-actuator) arms that provide the end-effector with either the full six or five freedoms. For each robot analysed, we identify the special configurations and provide the typical practical information about the behaviour of the actuators as the end-effector of the robot is guided at finite and reasonably uniform speed along a path that passes close to a special configuration. But we give additional understanding about, and distinctions between, special configurations by identifying both transitory and full-cycle displacements of certain actuated joints when the robot remains right at the special configuration and while the end-effector is held stationary.
Redundant Robotic Systems
Authors: Davidson Joseph K , Hunt Kenneth H
Published: November 2023

A robot is said to be ‘redundant’ when it has a superabundance of actuated joints with respect to the task it is required to perform. In Chapter 7, we described methods for finding the finite number of distinct assembly-configurations that are available in a six-actuator serial arm when the location of its end-effector body is held fixed; except when an assembly-configuration is special, there can be no transitory movement at any actuatable joint. But when a seventh actuatable joint is embodied in the arm, a one-parameter family of assembly-configurations is available for choice.
General Introduction to the Circuit Modelling of Multiconductor Lines
Authors: FachÉ Niels , Olyslager Frank , De Zutter Daniël
Published: November 2023

This book is organized in two parts. The first part (Chapters l–4) deals with the circuit modelling of muiticonductor waveguides. The second part (Chapters 5–9) deals with the fullwave electromagnetic modelling of some particular subclasses of these waveguides. The present chapter starts with a short general introduction to both problems and is followed by a much more extensive introduction to the circuit modelling problem. An extensive introduction to the electromagnetic field problems treated in this book is given in Chapter 5.
Circuit Description of General Lossy Multiconductor Waveguide Structures
Authors: FachÉ Niels , Olyslager Frank , De Zutter Daniël
Published: November 2023

In the previous chapters the network description of single and coupled multiconductor waveguides was developed in a systematic way highlighting the physical background and the concepts introduced in order to come to a systematic network description.

In Chapter 3 the network description for coupled waveguides was restricted to two coupled lossless waveguides. In the present chapter the network description will be extended to an arbitrary number of coupled multiconductor waveguides and losses will be included as well. As we assume that the reader is familiar with the concepts introduced in the previous chapters we will restrict ourselves to the general outline and the final results of the problem. However, the chapter, and in particular the notation used to indicate field quantities on the one hand and circuit quantities on the other hand, is organized in such a way that the reader should be able to read this chapter independently of the previous ones.
The Basic Models
Authors: Collie John G , Eng F R S F , John R , Phil Thome D
Published: November 2023

In this chapter the two most important models of two-phase gas-liquid flow—the ‘homogeneous’ model and the ‘separated flow’ model-will be discussed. These treatments have been used in engineering design calculations in a number of diverse applications. Such applications often involve high pressures and temperatures and specialized treatments as applied to particular flow patterns may not be possible since the flow pattern or, more likely, the several successive flow patterns, may be unknown. The treatments discussed have therefore been applied to the calculation of pressure drops and density without particular reference to the flow pattern.
Subcooled Boiling Heat Transfer
Authors: Collie John G , Eng F R S F , John R , Phil Thome D
Published: November 2023

After a brief comment concerning heat transfer to a single-phase liquid flowing in a channel, the remainder of this chapter is taken up with the topic of heat transfer to a flowing subcooled liquid under conditions where nucleate boiling takes place at the channel wall. The criteria necessary for the onset of nucleation with forced convection are considered in detail. This is followed by a description of alternative methods for calculating the change of heat transfer rate and surface temperature with the independent variables such as velocity, heat flux, and liquid temperature. Finally, the various possible mechanisms of subcooled boiling are considered.
Critical heat flux in forced convective flow—2. More Complex situations
Authors: Collie John G , Eng F R S F , John R , Phil Thome D
Published: November 2023

In the previous chapter the critical heat flux conditions for water flowing in vertical uniformly heated tubes were discussed. In this chapter the effects on the critical heat flux of (a) non-uniform heating, (b) non-circular geometry, the use of fluids other than water, (d) liquid-vapour mixtures at the channel entrance, and (e) unstable hydrodynamic conditions will be reviewed. In addition the present knowledge regarding the mechanism of the critical heat flux will be discussed. Finally the question or critical heat flux on the outside of horizontal tube bundles in cross flow is addressed.
Introduction
Authors: Marciniak Krzysztof
Published: November 2023

Numerically Controlled (NC) milling machines are very much like the analogous conventional machines, but their construction has been modified to meet the following special NC demands The spindle is used with greater efficiency by keeping it in the cut for most of the time. Wasted, redundant, and non-productive motions and waiting times are reduced or eliminated. The same holds true for the other features of the machine, so drives, gears, ways, screws, and so on are liable to be worn out more quickly. This is the reason why machine construction has to be particularly rigid and the driving mechanisms specially designed to improve accuracy and robustness.
Curve segments
Authors: Marciniak Krzysztof
Published: November 2023

where w;(t) are scalar functions (called basic functions) and 8; are column matrices of coefficients. The coordinates of point P( t) are linear combinations of functions w;(t). For this reason the form (4.1) is sometimes referred to as a linear segment.
Surface patches
Authors: Marciniak Krzysztof
Published: November 2023

We restrict ourselves to the linear methods of surface patch definition. The important property of linearity is that the surface can be represented by a mapping R(u) = R(u1, u2) of the form where a; are coefficients and b1(u) = b1(u1,u2) are scalar bivariate functions, termed basis functions. They usually form a basis of the linear space.
Contouring on 2CL milling machines
Authors: Marciniak Krzysztof
Published: November 2023

On NC milling machines with a control unit of type 2CL a tool moves in such a way that the direction of the rotation axis is constant. This kinematic constraint means that a tool movement may be uniquely defined by the movement of an arbitrarily chosen point on its axis of rotation. In addition, on 2CL milling machines movements are restricted to flat trajectories in mutually parallel planes (Fig. 10.1). Rapid movements do not conform to this restriction and may be used to move a cutter to the next parallel plane. The contouring trajectory consists of machining movements in mutually parallel planes and rapid changes of machining planes. The tool trajectory is then similar to the contours on maps.
Plane stress and plane strain
Authors: Mohr G A
Published: November 2023

The basic constitutive relationships of Chapter 2, the energy-based displacement method of Chapter 3, and some of the interpolation functions of Chapter 5 are used to develop several finite elements for the analysis of plane stress and plane strain. In the first two sections explicit formulations are obtained using Cartesian polynomial interpolations. These provide a useful introduction to two-dimensional finite elements but for higher-order elements interpolation functions expressed in terms of dimensionless coordinates and numerical integration are used in the remainder of the text.
Boundary solution techniques
Authors: Mohr G A
Published: November 2023

The boundary element method is based upon the use of integral equations. To obtain an integral equation solution to the problem of determining the distribution of a function y = y(s) in a domain one begins by expressing the solution in the form and integration by parts is used to force the solution to the boundary. In practice F(x, s) consists of two parts: a forcing function b(x) describing the variation in intensity of some ‘loading’ effect, and a response or influence function G(x, s) which gives the response at s resulting from a point loading at x.
Generalization of constraint techniques and optimization programs
Authors: Mohr G A
Published: November 2023

We have seen the application of constraints to finite element formulations at many points in preceding chapters. Of particular note are the penalty factor, Lagrange multiplier, and basis transformation techniques introduced in Chapter 4 and frequently used subsequently. The present chapter begins by examining the relationships between these methods, giving particular attention to conversion of Lagrange multiplier formulations to obtain equivalent penalty formulations. Application of the latter to integral constraints is then discussed in relation to both variational and weighted residual formulations. Finally, the chapter closes with several programs for the optimization of finite element models of problems in both solids and fluids.
Constraint Methods Applied in Contact Problems with Small Displacements
Authors: Zhong Zhi-Hua
Published: November 2023

Contact problems are characterized by contact constraints which must be imposed on contacting boundaries. To impose the contact constraints, two basic methods are available. These two basic methods are the Lagrange multiplier method and the penalty method (Kikuchi and Oden 1988). Other constraint methods based on the basic methods have also been proposed and applied. For example, a perturbed Lagrangian method is discussed in Simo et al. (1985). In this chapter, alternative constraint methods are introduced and applied in contact problems with small displacements. Basic features of the alternative constraint methods in different applications will be identified. It must be pointed out, however, that the discussions on constraint methods are not exclusive to this chapter. The performance of alternative constraint methods will also be examined in subsequent chapters, for example in Chapters 7 and 9.
Dynamics Of Charged Particles
Authors: Woods L C
Published: November 2023

A plasma is a mixture of positive ions, electrons and neutral particles, electrically neutral over macroscopic volumes, and usually permeated by macroscopic electrical and magnetic fields. In addition to these ‘smoothed’ or averaged electromagnetic fields, which with laboratory plasmas are often imposed from outside the plasma volume, there are the microfields due to the individual particles. The trajectories of the charged particles are thus continuously modified by a range of electromagnetic forces, the average fields acting like body forces and the microfields like collisional forces. The microfields are responsible for the transmission of pressure and viscous forces, for the conduction of particle energy, and for the friction forces between diffusing components of the plasma. Some care is needed in dividing the continuum of electromagnetic forces into their macroscopic and microscopic components, but once this has been achieved, there is little formal distinction between the kinetic theory of neutral gases and the kinetic theory of magnetoplasmas. The most important practical distinction is that in strong magnetic fields, for cross-field transport, the terms second-order in the Knudsen number E dominate the first-order terms. This occurs because the 0(∈) terms are much more strongly suppressed by the magnetic fields than are the O(∈) terms.
Design, Assembly, And Testing Of A Prototype Ultrasonic Motor
Authors: Sashida Toshiiku , Kenjo Takashi
Published: November 2023

We have so far discussed the theoretical aspect of the ultrasonic motor. In this chapter, our subject is the actual assembly and testing of a prototype ultrasonic motor. In Section 3.9 we examined various limiting conditions as factors affecting motor design in general. Here we show some calculation examples and make comparisons with theory based more or less on a complete motor. Design experience with ultrasonic motors, unlike that with electro- magnetic motors, has been very limited and there still remain many unresolved questions about its characteristics. Thus the authors feel that it is unrealistic to present a design theory for the ultrasonic motor in a final and orderly manner, and it is their wish that the material presented in this chapter may serve as a starting point for further research.
Periodic Laminar Regime
Authors: Zdravkovich M M
Published: November 2023

The steady, elongated and closed near-wake becomes unstable whenRe> Reosc, where the subscriptosc stands for oscillation. The transverse oscillation starts at the end of the near-wake and initiates a wave along the trail as shown in Fig. 1.6(a). It has been pointed out in Chapter 2 that the maximum adverse pressure gradient also occurs around the confluence point at the near-wake end. The coincidence of the location of the instability and the adverse pressure gradient indicates their interrelationship.
Transition In Boundary Layers
Authors: Zdravkovich M M
Published: November 2023

The advance of transition to turbulence in free ‘shear layers towards the separation line is impeded in the TrSL3 regime because the separated shear layers are squeezed beyond the separation by the accelerated free stream. This stabilizing effect begins to diminish with risingRe at the beginning of the TrBL state of flow. The perturbed boundary layers adhere longer to the surface and the separation is gradually displaced further downstream. The separated free shear layers become more and more aligned with the adjacent free stream and the aforementioned stabilizing effect is gradually weakened until eventually the transition to turbulence reaches the displaced separation line.
Fully Turbulent State
Authors: Zdravkovich M M
Published: November 2023

The least explored and known is the turbulent or T state of flow. It is eventually reached when all three disturbed flow regions - wake, shear and boundary layers - are ‘fully’ turbulent. The transition in boundary layers moves upstream towards the stagnation region asRe rises in the TrBL4 regime. The advance is fast in the region of the adverse pressure gradient and becomes more and more retarded in the region of the favourable pressure gradient.
Solutions Of The N-S Equations
Authors: Zdravkovich M M
Published: November 2023

The equations of motion of viscous fluid, expressed in a differential form, are a statement of equilibrium of all forces acting on the fluid and the rate of change of momentum. The surface forces are expressed through the stress tensor with pressure and friction forces acting normally and tangentially to the surface, respectively. The relationship between the stress and rate of strain for a Newtonian fluid is linear.
Vortex Models And Stability
Authors: Zdravkovich M M
Published: November 2023

The simplest vortex model is the Helmholtz point-vortex in an irrotational and two-dimensional flow and its counterpart the Biot-Savartline-vortex in an irrotational and three-dimensional flow. The flow around the pointvortex is described in a polar coordinate system by the following velocity potential,w, radial,u, and tangential,v, velocity components
Free Stream Turbulence
Authors: Zdravkovich M M
Published: November 2023

The free stream is usually turbulent in most practical applications. Most research, however, has been carried out in wind/water tunnels with low-level turbulence. A particularly strong effect of very low free stream turbulence is observed in three transition states of flow past cylinders. This means that the experimental data obtained in smooth flows cannot be used for practical flows without correction.
Electromagnetic Waveguides and Transmission Lines
Authors: Olyslager Frank
Published: November 2023

This monograph deals with the theoretical aspects of the circuit modelling of high-frequency electromagnetic structures using the Lorentz reciprocity theorem. This is the first book to cover the generalization from closed structures to open-boundary waveguides and circuit structures. The author has developed a new way to represent a general waveguide by transmission lines: and was awarded the Microwave Prize of the IEEE for this work. The first part of the book discusses the construction of transmission line models for waveguide structures. Then the incidence of external electromagnetic waves on high-frequency structures is studied, and finally the concepts derived in the earlier parts of the book are generalized to reciprocal and non-reciprocal anisotropic, bi-isotropic, and bianisotropic materials.
Transmission Lines For Full-Wave Fields
Authors: Olyslager Frank
Published: November 2023

In the previous chapter it was shown that at low frequencies Maxwell’s equations in electric waveguides can be reduced to transmission line equations. The aim of this chapter is to extend these transmission line equations to all types of isotropic waveguides and to arbitrary frequencies. Before being able to construct these models, it will be instructive to study some properties of general isotropic waveguides.
Weak and weak* convergences in Banach spaces
Authors: Donato Patrizia
Published: November 2023

We recall in this chapter the main properties of weak and weak* convergence in a Banach space. We also detail these notions for the particular case of L  p-spaces.
Rapidly oscillating periodic functions
Authors: Donato Patrizia
Published: November 2023

In this chapter we study a relevant class of periodic oscillating functions, which plays an essential role in homogenization theory. We turn our attention, in particular, to functions of the form where a is a periodic function and where, from now on, ε > 0 takes its values in a sequence which tends to zero. Let us point out that if a is Y-periodic (see Definition 2.1 below), then a  ε is εY-periodic. Moreover, as can be seen in the examples below, the smaller ε is, the more rapid are the oscillations.
Some variational elliptic problems
Authors: Donato Patrizia
Published: November 2023

We study in this chapter some classical elliptic partial differential equations in the framework of weak solutions. The problems we deal with are linear elliptic partial differential equations with different boundary conditions: Dirichlet, Neumann, Robin and periodic conditions. In all these cases, the existence and uniqueness of the solution are obtained by applying the Lax–Milgram theorem. This important theorem is proved in Section 4.2 below.
Homogenization of elliptic equations: the convergence result
Authors: Donato Patrizia
Published: November 2023

In Chapter 5 we have studied the particular cases of the dimension one and of layered materials. As we already mentioned, to study the general TV-dimensional case we need to introduce some auxiliary functions which are solutions of periodic boundary value problems in the reference cell Y.
The multiple-scale method
Authors: Donato Patrizia
Published: November 2023

In this chapter we apply the multiple-scale method to the study of problem (6.1). The method is presented in Section 7.1 and a formal asymptotic expansion for u  ε is obtained. The goal of Section 7.2 is to prove the error estimate stated in Theorem 6.3.
Tartar’s method of oscillating test functions
Authors: Donato Patrizia
Published: November 2023

We begin this chapter with the proof of Theorem 6.1. This is done by using the method introduced by Tartar (1977a, 1978). In Section 8.2 we prove the convergence of the energy associated to problem (6.1). This convergence allows us to show in Section 8.3 a corrector result. Sections 8.4 and 8.5 contain some further convergence properties of the solution u  ε of the model problem (6.1).
The two-scale convergence method
Authors: Donato Patrizia
Published: November 2023

In the first two sections of this chapter, we present the two-scale convergence method and we use it in Section 9.3 to prove again Theorem 6.1. As the multiplescale method, it also takes into account the fact that we have a ‘macroscopic’ scale x and a ‘microscopic’ one x/ε.
Homogenization in linearized elasticity
Authors: Donato Patrizia
Published: November 2023

In this chapter we are interested in the asymptotic behaviour as ε → 0 of the solution of the linearized elasticity system introduced in Section 5.2. We refer to Duvaut (1978), Sanchez-Palencia (1980), Bakhvalov and Panasenko (1989), Oleinik, Shamaev, and Yosifian (1992), Sanchez-Hubert and Sanchez-Palencia (1992) for this subject and to references herein.
Homogenization of the wave equation
Authors: Donato Patrizia
Published: November 2023

In this chapter we are concerned with the asymptotic behaviour as ε → 0 of the solution u  ε = u  ε  (x, t) of the wave equation introduced in Section 5.2 (Example 5.3), namely, where as in the previous chapter, the operators div and ▽ are taken with respect to the space variable x ∈ Ω and ‘ denotes the derivative with respect to the time variable l ∈]0, T[ with T > 0.
General approaches to the non-periodic case
Authors: Donato Patrizia
Published: November 2023

In this chapter we present some results concerning the convergence of the solutions of partial differential equations with non-periodic coefficients. For simplicity, we will only present results concerning the elliptic problems. All the results can be extended to the heat and wave equations, as well as to the linearized elasticity system.
M
Authors: Perrot Pierre
Published: November 2023

Macroscopic state—The state of a system defined by macroscopic quantities: temperature, pressure, volume, composition, etc. The statistical probability of a macroscopic state is given by the number of microscopic states allowing its realization.
N
Authors: Perrot Pierre
Published: November 2023

At equilibrium, if T > 0, the entropy increases with internal energy, whereas if T < 0, it varies inversely. Consider for instance an assembly of moment-carriers in a magnetic field. If every moment is oriented in the reverse direction to the field, the energy of the system is a maximum and its entropy a minimum. This state corresponds to the temperature T = - 0 K. If all the moments are oriented in the direction of the field, the energy of the system is then a minimum and its entropy is also a minimum. This state corresponds to a temperature T = +0 K. Between these two states, the entropy of the system goes through a maximum (directions of moments haphazard), a state corresponding to an infinite temperature.
V
Authors: Perrot Pierre
Published: November 2023

Vacancy—The name given to an unoccupied crystal site. Vacancies are point defects which are thermodynamically stable. In fact, the formation of a vacancy at a site, an endothermic phenomenon (ArH > 0), correspondingly introduces disorder (Ar S > 0). As a consequence, there is an equilibrium vacancy concentration which is calculated by seeking the minimum of the function G =H -TS.
W
Authors: Perrot Pierre
Published: November 2023

Waage, Peter (1833-1900) —Norwegian chemist who, together with Cato Guldberg, expressed the mass action law in a mathematical form in 1864. Wagner, Carl (1901-1977) —German physical chemist and metallurgist, who made an important contribution to the study of defects in crystals and in dilute solutions. He introduced interaction parameters.
Other Functions Defined by Integrals
Authors: Andrews Larry C
Published: November 2023

In addition to the gamma function, there are numerous other special functions whose primary definition involves an integral. Some of these functions were introduced in Chap. 2 along with the gamma function, and in this chapter we consider several others.
Legendre Polynomials and Related Functions
Authors: Andrews Larry C
Published: November 2023

The Legendre polyrwmials are closely associated with physical phen omena for which spherical geometry is important. In particular, these polynomials first arose in the problem of expressing the newtonian potential of a conservative force field in an infinite series involving the distance variables of two points and their included central angle (see Sec. 4.2). Other similar problems dealing with either gravita tional potentials or electrostatic potentials also lead to Legendre polynomials, as do certain steady-state heat conduction problems in spherical solids, and so forth.
Other Orthogonal Polynomials
Authors: Andrews Larry C
Published: November 2023

Sets of orthogonal functions play an extremely important role in analysis, primarily because functions belonging to a very general class can be represented by series of orthogonal functions, called generalized Fourier series.
Blackage and wall proximity
Authors: Zdravkovich M M
Published: November 2023

The walls in wind and water tunnels induce a confining effect on the model that has been termed blockage. The blockage ratio is defined as the ratio of the cylinder diameter to the breadth of the test section, D/B. A convenient classification of blockage effects on circular cylinders is as follows: