bluuebunny/crossref_metadata_2025 huggingface dataset:
Cognition of Physical and Built Environments
Authors: Golledge Reginald G.
Published: November 2020

Environmental knowledge is acquired by interacting with, or experiencing, different environments. The interaction may be direct and active, as would be the case when a person lives in, travels through, or otherwise physically experiences a particular environment. Interaction may also take place, however, by accessing different sources of information including such things as photos, slides, movies, videos, paintings, or other visual representations, as well as haptically perceived information such as might be acquired from tactual maps, table models, or different types of sensing devices. Information abstracted from these many sources is stored in long-term memory as part of a general knowledge structure. As the need arises, such information is processed to provide knowledge of location, distribution, pattern, dispersion, connectivity, configuration, and other properties, which assist in preparing travel plans and activating movement. There are of course many “environments,” and it makes little sense to refer to “the environment.” Even the “physical” environment encompasses the markedly dissimilar worlds of landforms, marine, surface and groundwater domains, vegetation, atmosphere, weather, and climate. Add to that the complexities of other external realities such as the built and transformed landscapes of human occupance, and it makes even less sense to regard them as one. Often these domains compete with each other via invasion and succession procedures (e.g., the invasion of agricultural land by urban uses; the successful invasion of inner city residential areas by expansion of commerce, business, and industry; the invasion of natural grasslands by domestic plants and animals), while at other times they exist in harmony. Perhaps the one common feature is that they are assumed to exist independently of mind—that is, they are “external” to mind. Assuming this to be so, the concept of “environmental cognition” can be examined. In this chapter, we will first discuss the basic spatial elements or components that allow both differentiation and clustering of phenomena found in large- and small-scale environments. This is followed by discussion of the components of an environmental knowledge structure, highlighting both individual and integrated components of knowledge, and emphasizing spatial characteristics.
Beyond Rationality: Clarity-Based Decision Making
Authors: Kaplan Stephen
Published: November 2020

The study of how people make decisions has long been dominated by the economic man or rationality model. In recent years researchers have extended the study of decision making into the spatial context. Given the pervasive role of the rationality model it was not surprising to see reliance on it in this new domain as well (Golledge & Timmermans, 1987; Timmermans, this volume). There are, however, at least two reasons why one might have hoped for a broader perspective. First, given its obvious kinship to the area of environmental cognition, research on spatial decision making could have reflected the concern for cognitive structure central to the wayfinding literature. Second, the rationality model has increasingly been the subject of searching questions and criticism. Cracks have been appearing in the once near-monolithic support for this model. A number of psychologists have been quite articulate about what they see as serious deficiencies in this approach (Einhorn & Hogarth, 1985; Herrnstein & Mazur, 1987; Kruglanski & Ajzen, 1983; Simon, 1957; Wallach & Wallach, 1983). Even economists have expressed serious reservations (Bell & Kristol, 1981; Earl, 1983a; Eichner, 1983; Kuttner, 1985; Lutz, 1987). Decision theorists have not been insensitive to these concerns; many modifications have been proposed (see Jungermann, 1983, for an extensive review). If there is a consensus among them, it is far from obvious. In the absence of such a consensus, many stalwart investigators (including economists and planners) continue within the comfortable and familiar confines of the classical framework. In the discussion that follows, the term “rationality” will be used to refer to the classical rationality position that still endures in many quarters, and that still serves as a center of gravity for the multitude of dissatisfied revisionists. In its simplest form, the position can be summarized as stating that people have perfect knowledge and that they strive to maximize their gains. A most interesting analysis of the increasingly obvious inadequacy of the rationality model and of how planners are coping with this state of affairs is provided by E.R. Alexander (1984). The picture he paints is essentially one of a paradigm decline, with heroic efforts on the part of practitioners to carry on nonetheless.
Developmental Perspectives on Decision Making and Action in Environments
Authors: Hart Roger A. , Conn Michael K.
Published: November 2020

The task we have been set is to review developmental theory concerning how individuals act in real-world environments. To simplify this difficult task we have emphasized the developmental span of childhood, the area of our professional expertise. Before proceeding with the review, a few comments regarding the framework of this book and, within it, the definition of our task will enable us to illuminate some of the assumptions inherent in the structure of this volume and to explain how this has affected our conceptualization of the problem. The stated goal of this book is to look at the separate areas of human relatedness to the environment that are recognized by “most research in environmental psychology”: environmental cognition, environmental appraisal and decision making, and action in environments (see Table 1.1 in Chapter 1 of this volume). We agree that although such a separation of cognition and evaluation from action is a reflection of the dominant tendency of research, it is true of only some theories. To accept this division and to discuss primarily action would prevent us from emphasizing those theorists who have argued that human relatedness to the environment must be thought of holistically and dynamically. Consequently, although we have tried to emphasize action, this chapter actually deals simultaneously with cognition and appraisal. The question of why more integrative and holistic theories have been largely ignored is itself important. We argue that the answer lies in a fear by psychologists of such research because it cannot easily meet the traditional tenets of what constitutes good theory—building through experimental research design. A second problem in the task definition is the use of the word “space.” We should not simply be addressing “spatial decisions and actions” but environmental decisions and actions. In the field of environmental psychology the terms “space” and “environment” are commonly used synonymously. We think of space as just one characteristic of objects in the environment. Unfortunately, space is the characteristic that most environmental cognition research has addressed. This is somewhat understandable, for environmental psychology finds its distinctiveness in the study of the large-scale environment in which space (spatial relatedness) is the most distinguishing variable.
A Closing Word
Authors: Bonner Thomas Neville
Published: November 2020

Despite all the changes in undergraduate medical education after World War II, especially in its core of scientific training, it actually had shifted only slightly in essential ways by the end of the twentieth century. If a student from an earlier era sat down in the classrooms and clinics of the 1990s—although doubtless overwhelmed by the new knowledge and technology—he or she would still find much that was familiar in the teaching methods, curriculum, conduct of clinics, bedside training, laboratory instruction, and educational preparation of fellow students. “The medicine of 1900,” writes William Bynum, “[is] closer to us almost a century later than it was to the medicine of 1790.” The historic differences among nations in teaching methods, too, though less striking than in earlier times, were still visible in the characteristic responses of medical educators and students to the social and scientific changes. Alone among the professions, education for medicine had come to combine a long period of theoretical study with an intensely practical experience in the observation, handling, and treatment of patients. The resulting tension and shifting balance between academic study and clinical training, between theory and practice, between medicine as art and medicine as science, has been the perpetual condition of medical pedagogy since the Enlightenment. That a different balance was struck at different times in different nations because of differing social and political circum- stances is the underlying theme of this book. In the first half of this century, if a boundless faith in science and the ultimate rationality of medicine came to dominate nearly everywhere, that faith has been overwhelmed in our own time by postmodern doubts about human progress and the explanatory powers of science. But the pendulum will doubtless swing again. In any case, for most educators and students, the ideal remains what it has been for most of the period covered in this book—a unity of systematic academic study, especially in the sciences, with hands-on experience to create a physician who thinks critically, can solve problems, possesses a wide knowledge of underlying disease processes, and is skilled at applying what has been learned to real-life situations.
Standard States
Authors: Anderson Greg M. , Crerar David A.
Published: November 2020

At this point we have introduced the activity as a ratio of fugacities (Chapter 11). The fugacity of a constituent, in turn, we saw was a quantity very much like a vapor pressure or partial pressure, which is directly linked to the Gibbs free energy of that constituent, such that a ratio of fugacities leads directly to a difference in free energies. The fugacity was introduced as a means of dealing with gases and gaseous solutions, and it is measured by measuring gas volumes or densities. Nevertheless, there is nothing restricting its use to gaseous constituents, and we suggested that it is very useful to regard the fugacity as a state variable; as a property of any constituent of any system, solid, liquid, or gas, whether equilibrated with a gas or not, and whether measurable or not. This leads to the easiest approach to understanding activities. The activity of a constituent is the ratio of the fugacity of that constituent to its fugacity in some other state, which we called a reference state. We then showed through consideration of the Lewis Fugacity Rule, which is an extension of Dalton's Law, that for ideal solutions of condensed phases, the activity of a constituent equals its mole fraction, if the reference state is the pure constituent at the same P and T. Deviations from ideal behaviour are then conveniently handled by introducing Henryan and Raoultian activity coefficients. The utility of these relations would be quite sufficient for retaining the activity in our collection of thermodynamic parameters, but in fact the activity can be applied to a much wider range of conditions, simply by varying the choice of reference state. We now examine the various possible choices of this reference state, and the resulting equations and applications. In the most general sense, the fugacity and activity concepts satisfy the need to relate system compositions to free energy changes. That a single parameter, the activity, can do this for essentially any system is a tribute to its tremendous versatility.
Simple Mind Machines
Authors: Gelernter David
Published: November 2020

we plunge now into the deepest, trickiest, most treacherous and remarkable undersea cavern in the whole coral reef, the question of simulated experience. when we get to the bottom we will be face to face with the fundamental question of artificial intelligence (henceforth AI). we won’t know how to solve it, but we will be shining a flashlight in its face. what does it mean to think? How does thinking work? Not “how does the brain work,” but what does the thinking process consist of, in logical terms? we don’t need to understand lungs to realize that respiration has something to do with grabbing air, letting it soak in somehow and then pushing it out. Thinking is (one suspects) just as basic a physiological process as breathing; how does it work? Presumably it’s not mere random helter skelter scurrying about. There is some system at work, some process, presumably. Even when you are not hard at work solving a math problem, planning a strategy or wracking your brain for the name of someone’s daughter, there is something ticking over in there, as steadily (maybe even as rhythmically) as breathing. what is this process? As usual, we have a particular, concrete problem and a software solution in mind. The problem is crucial to Mirror worlds: How do we make the experience key work? In answering we will (again) be addressing a major problem in the non-Mirror world as well. In the last chapter, I discussed the extraction of information from fastflowing data streams at the source. we turn now to oceans of data that have accumulated in databases. what can we do with this stuff? All those multi-billions of records on file? Here, the focus is different. You don’t worry so much about extracting information fast, as the data values fly by. You focus instead on the problem of comparing many stored incidents or situations. In pursuing this concrete problem, I’ll keep the deep questions and long-term implications at bay, for the most part—but they do have a tendency to wind their tendrils around the subject matter in this chapter. I will be describing a “simulated mind” designed for a well-defined, utilitarian purpose.
Capabilities and Merits of Long-term Bio-optical Moorings
Authors: Marra John
Published: November 2020

There are primarily three ways in which the ocean can be sampled. First, depth profiles of water properties can be collected. The sampling resolution for depth profiles can be very high (<1 m), and time resolution can be good under some circumstances. But since relatively few stations can be completed, geographic coverage is generally poor. Variability in space can be optimized if data can be collected while the ship is underway. In this second sampling mode, water is pumped aboard for sampling, or else sensing instruments are towed behind the ship. This method vastly improves sampling horizontal variability; however, depth resolution is compromised, and measurements cannot be ordered in time. The third method is to place instruments in the ocean, either tethered to moorings or on drifters. While depth resolution is only moderately good (typically, tens of meters), and spatial data nonexistent, this method has the advantage, unobtainable with the other modes, of high resolution in time. While moorings and drifters have been in the repertoire of physical oceanographic sampling for some time, it is only recently that they have been used to sample biological and optical properties of the sea. In this chapter, I discuss the capabilities of this kind of sampling from the point of view of a recent program, the BIOWATT Mooring Experiment in 1987. One of the express purposes of this experiment was to expand the range of variables that can be measured from moored instrumentation. Here, I will show how the time resolution made possible with moored sensors allows the measurement of parameters of phytoplankton production on diurnal time scales, as well as allowing a look at seasonal variability. The BIOWATT Mooring Experiment was a collaboration among a large number of people, all of whom contributed to its success. It was the first deployment of a mooring with a variety of sensors and whose goal was to record the optical, biological, and physical variability over a seasonal cycle. The idea for this type of experiment for BIOWATT originated with Tom Dickey and his (then) graduate student, Dave Siegel.
Water System Evidence of Greek Civilization
Authors: Crouch Dora P.
Published: November 2020

Attention to water supply and drainage is the sine qua non for urbanization, and hence for that human condition we call civilization. In fact, development of water supply, waste removal, and drainage made dense settlement possible. (In this book, drainage is used to mean the leading away from a site of all sorts of water, whether clean or dirty.) In spite of the importance of this factor for human history, relatively little attention has been paid to the history of water management, more to the histories of food supply and of commerce as determiners of urbanization. To compensate for that deficit, this is a study of the relationship between water management and urbanization. Other factors contributing to urbanization are discussed briefly in Chapter 6. Many of the “working conclusions” in this chapter and elsewhere are my inferences from the physical data discovered by archaeologists. Very little written evidence has come down to us from the Greek period. We are in the position of reasoning backward from the answers to the questions—always a risky business (Pierce, 1965, 5.590). This is not an uncommon problem in Greek history. Mortimer Chambers has pointed out in a talk on travelers to ancient Greece, given at the American Institute of Archaeology meeting, San Francisco, 1990, that if we had to rely on Greek literature for evidence, we would never know that they had ever painted any vases! Yet no one is suggesting that we desist from the study of vases because the surviving ancient Greek writings do not discuss them. No—we go to the vases themselves for the strongest evidence. In this chapter the emphasis will be on what had to be discovered and organized so that there could be a complete system of water management for an ancient Greek city. If we try to put ourselves back into pre-Hellenic centuries when the world seemed “new,” and look about with curious eyes and that great tool the inquiring mind, what will we see? What did “the water problem” consist of? Millennia of observation had enabled the ancient peoples to become expert about many aspects of their environment such as the stars, so that by about 5000 years ago the constellations of the zodiac were recognized and named, and the science of astronomy well begun.
Urban Patterns in the Greek Period: Athens, Paestum, Morgantina, Miletus/Priene, and Pergamon as Formal Types
Authors: Crouch Dora P.
Published: November 2020

In order to assess the impact of the delivery and drainage of water on the urban pattern in the ancient Greek world, it is necessary to have clear ideas of what forms their cities took. Thus a brief discussion of urban patterns will be useful. Traditional descriptions of ancient Greek cities characterize them by typical street patterns, usually two major types: the Hippodamean grid of Miletus of the fifth century, and the terraces like the blades of a fan found at Pergamon of the late third and second centuries, called “scenographic urbanism.” Yet a more careful examination of the evidence suggests that for different centuries B.C., there are many more urban types than two. Examples standing for both the repertory of physical patterns and the changes in those patterns over time that we may cite are: 1. 7th century B.C.—Akragas (frontispiece): irregular hill-top site of the archaic period 2. 6th century—Paestum (Fig. 5.IB): “bar and stripes” 3. 5th century—Athens (Fig. 5.1A): organic, focused on central acropolis and agora, similar to Akragas pattern 4. 5th century—Morgantina (Fig. 5.1C): typical West Greek pattern of two flat hills with residential quarters grid platted and lower agora between them 5. 4th and 3rd centuries—Priene (Fig. 51.D): based on prototype grid at Miletus (early 5th century—Fig. 22.4) and refinement of grid as used at Rhodes (mid to late 5th century—Fig. 8.3), an adaption of Hippodamean regularity to a small plateau 6. 3rd and 2nd centuries—Pergamon (Fig. 5.1E): scenographic urbanism, with wedge-shaped terraces It is difficult to classify urban plans solely by pattern or by century. This is because the changes did not go together in any simple fashion. Inspection of the street patterns of ancient Greek cities, and the relation of those patterns to the sites, allows them to be classified into five basic types, which for easy remembrance I name after representative cities of each type: 1. Athens-type. A general rule for cities of a[n ancient] culture states that “the capital city is unlike the others in form.” Athens, a seemingly formless, organic city, is quite unlike the well-regulated cities (many of them colonies) of the other types.
Scale Differences: Akragas and Morgantina
Authors: Crouch Dora P.
Published: November 2020

Can we discern differences in the way water was managed at larger and smaller Greek cities? Let us take two Greek cities in Sicily as case studies, examining them in some detail as to area, population, date, geological situation, and the water system elements known at each. The aim of this exercise is to begin to understand the impact of scale differences on the clusters of water system elements in ancient cities. Useful examples are Akragas—modern Agrigento—and Morgantina (Figs. 15.1, 15.2). Akragas is located on the south coast of Sicily, approximately in the center, and occupies a dramatic site on a hill between two rivers. The earliest settlement—and later the medieval town—were located on the highest peak of the 280-meter hill (Storia della Sicilia, 1979, map 1), but during classical and Hellenistic times the city spread down the hill to the wide and gentle valley to the south, which then rises again to form a ridge that separates that valley from the plain leading to the sea. In the sixth and fifth centuries B.C. a line of temples was built along the lower ridge, forming today the single largest, best preserved, and most impressive group of Greek temples anywhere. These architectural glories were possible because of the size and wealth of the city, the same factors that necessitated and made possible the extensive water system of the city. In contrast, Morgantina was built inland, on a ridge at the juncture of the Catania plain with the plateaus of the center of Sicily. This ridge stands 578 to 656 meters above sea level, higher by 300 to 350 meters than the valleys to the north and south, but lower than the site of the nearest modern town, Aidone (885 meters), about 3 kilometers away. Morgantina began as a prehistoric settlement of migrant tribes from Italy whose king, Merges, gave his name to the city. The earliest Sikel settlement was on Cittadella, the easternmost wedge of the ridge, during the archaic period, no later than the sixth century.
Urban and House Form Constrained by Water Resources—Morgantina
Authors: Crouch Dora P.
Published: November 2020

Although we may think that physical form of a city is mainly the result of cultural preferences interacting with the inherent potential of local materials, there are in fact even more basic constraints that constitute the substratum of every urban form because they are the basis of life itself. These factors are food, water, and the earth that provides them and makes life possible. The urban form makes explicit how the society provides food and water for its members and how they relate to the earth. Intentionally and unintentionally, the forms of the houses, the work places, the public buildings, and the open spaces reflect the people's values and ways of behaving, as well as what they know about their environment and how they manipulate it. We are so accustomed to analyzing modern cities or “primitive” cultures in these terms that to state them is to utter a truism, but in the study of ancient cities these ideas have been applied rarely if at all. One cannot exhaust this broad subject in one chapter, since the formal and technical details are not condensible, nor are the cultural-historic aspects susceptible to terse summary. Rather, we will take one basic constraint—water—and examine it in the light of the evidence from one particular place—Morgantina, Sicily—with just enough comparative material to make the details from Morgantina stand out clearly. This singular analysis will, I hope, suggest how fruitful it would be to study ancient urbanization in terms of the social and architectural results of resource management. The ordinary provisions for urban form and water management as they interrelated at one ordinary site are discussed in this chapter. The desired urban form dictated placement of water system elements, and the water potential was exploited to make possible the kind of physical arrangement preferred by the urban dwellers. In this provincial town, the standard solutions for water management were applied, and the resulting urban form differed from the typical only in the feature of the great steps, which as we have seen, were specifically built to solve a drainage problem. The street patterns of ancient Greek cities are discussed in Chapter 5, Urban Patterns.
Vibrational/Rotational Energy Levels
Authors: Baer Tomas , Hase William L.
Published: November 2020

The first step in a unimolecular reaction is the excitation of the reactant molecule’s energy levels. Thus, a complete description of the unimolecular reaction requires an understanding of such levels. In this chapter molecular vibrational/rotational levels are considered. The chapter begins with a discussion of the Born-Oppenheimer principle (Eyring, Walter, and Kimball, 1944), which separates electronic motion from vibrational/ rotational motion. This is followed by a discussion of classical molecular Hamiltonians, Hamilton’s equations of motion, and coordinate systems. Hamiltonians for vibrational, rotational, and vibrational/rotational motion are then discussed. The chapter ends with analyses of energy levels for vibrational/rotational motion. The Born-Oppenheimer principle assumes separation of nuclear and electronic motions in a molecule. The justification in this approximation is that motion of the light electrons is much faster than that of the heavier nuclei, so that electronic and nuclear motions are separable.
Potential Energy Surfaces
Authors: Baer Tomas , Hase William L.
Published: November 2020

Properties of potential energy surfaces are integral to understanding the dynamics of unimolecular reactions. As discussed in chapter 2, the concept of a potential energy surface arises from the Born-Oppenheimer approximation, which separates electronic motion from vibrational/rotational motion. Potential energy surfaces are calculated by solving Eq. (2.3) in chapter 2 at fixed values for the nuclear coordinates R. Solving this equation gives electronic energies Eie(R) at the configuration R for the different electronic states of the molecule. Combining Eie(R) with the nuclear repulsive potential energy VNN(R) gives the potential energy surface Vi(R) for electronic state i (Hirst, 1985). Each state is identified by its spin angular momentum and orbital symmetry. Since the electronic density between nuclei is different for each electronic state, each state has its own equilibrium geometry, sets of vibrational frequencies, and bond dissociation energies. To illustrate this effect, vibrational frequencies for the ground singlet state (S0) and first excited singlet state (S1) of H2CO are compared in table 3.1. For a diatomic molecule, potential energy surfaces only depend on the internuclear separation, so that a potential energy curve results instead of a surface. Possible potential energy curves for a diatomic molecule are depicted in figure 3.1. Of particular interest in this figure are the different equilibrium bond lengths and dissociation energies for the different electronic states. The lowest potential curve is referred to as the ground electronic state potential. The primary focus of this chapter is the ground electronic state potential energy surface. In the last section potential energy surfaces are considered for excited electronic states. A unimolecular reactant molecule consisting of N atoms has a multidimensional potential energy surface which depends on 3N-6 independent coordinates. For the smallest nondiatomic reactant, a triatomic molecule, the potential energy surface is four-dimensional (three independent coordinates plus the energy). Since it is difficult, if not impossible, to visualize surfaces with more than three dimensions, methods are used to reduce the dimensionality of the problem in portraying surfaces. In a graphical representation of a surface the potential energy is depicted as a function of two coordinates with constraints placed on the remaining 3N-8 coordinates.
Other Uses of Intensionality
Authors: Ashcroft E. A. , Faustini A. A. , Jaggannathan R. , Wadge W. W.
Published: November 2020

In Chapter 2 we presented what is essentially a creation myth of intensional programming—that far-sighted researchers studied intensional logic and then applied this knowledge by designing a language that embodied intensional principles. In fact, the whole project grew out of a more modest attempt to make fairly conventional Pascal-style programming mathematically acceptable. Indexed sequences were originally added so that programs which, in Pascal, used for-loops and reassignment, could be rewritten as equations involving temporal operators.
The Dynamical Theory of Liquid Crystals
Authors: Beris Antony N. , Edwards Brian J.
Published: November 2020

Liquid crystals (LCs) present a state of matter with properties—as the name suggests—intermediate between those of liquids and crystalline solids. Liquid-crystalline materials, as all liquids, cannot support shear stresses at static equilibrium. Their molecules are characterized by an anisotropy in the shape and/or intermolecular forces. Thus, there is the potential for the formation of a separate phase(s), called a “mesophase(s),” where a partial order arises in the molecular orientation and/or location, which extends over macroscopic distances. This partial long-range molecular order, reminiscent of (but not equivalent to) the perfect order of solid crystals, in addition to the material fluidity, is primarily responsible for the many properties which are inherent characteristics of liquid-crystalline phases, such as a rapid response to electric and magnetic fields, anisotropic optical and rheological properties, etc.—see, for examples, the reviews by Stephen and Straley [1974] and Jackson and Shaw [1991], the monographs by de Gennes [1974], Chandrasekhar [1977], and Vertogen and de Jeu [1988], and the edited volumes by Ciferri et al. [1982] and Ciferri [1991]. The variety of the liquid-crystalline macroscopic properties is such that trying to derive a theory capable of describing the principal liquid-crystalline dynamic characteristics can be a very frustrating task if one does not approach the issue in a systematic fashion. Characteristically, the main two theories that have been advanced over the last thirty years for the description of the liquid-crystalline flow behavior—the Leslie/ Ericksen (LE) theory and the Doi theory—are essentially models developed from a set theoretical frame work—continuum mechanics and molecular theory, respectively. Nevertheless, each one of these theories has a limited domain of application. The description of the dynamic liquid-crystalline behavior through the bracket formalism, as seen in this chapter, leads naturally to a single conformation tensor theory with an extended domain of validity. This conformation theory consistently generalizes both previous theories, which can be recovered from it as particular cases. This offers additional evidence that the wealth of inherent information in LCs can only be appropriately handled when pursued in a systematic, fundamental manner.
Physical Ultrasonics of Composites
Authors: Chimenti Dale , Rokhlin Stanislav , Nagy Peter
Published: November 2020

Physical Ultrasonics of Composites is a rigorous introduction to the characterization of composite materials by means of ultrasonic waves. Composites are treated here not simply as uniform media, but as inhomogeneous layered anisotropic media with internal structure characteristic of composite laminates. The objective here is to concentrate on exposing the singular behavior of ultrasonic waves as they interact with layered, anisotropic materials, materials which incorporate those structural elements typical of composite laminates. This book provides a synergistic description of both modeling and experimental methods in addressing wave propagation phenomena and composite property measurements. After a brief review of basic composite mechanics, a thorough treatment of ultrasonics in anisotropic media is presented, along with composite characterization methods. The interaction of ultrasonic waves at interfaces of anisotropic materials is discussed, as are guided waves in composite plates and rods. Waves in layered media are developed from the standpoint of the "Stiffness Matrix", a major advance over the conventional, potentially unstable Transfer Matrix approach. Laminated plates are treated both with the stiffness matrix and using Floquet analysis. The important influence on the received electronic signals in ultrasonic materials characterization from transducer geometry and placement are carefully exposed in a dedicated chapter. Ultrasonic wave interactions are especially susceptible to such influences because ultrasonic transducers are seldom more than a dozen or so wavelengths in diameter. The book ends with a chapter devoted to the emerging field of air-coupled ultrasonics. This new technology has come of age with the development of purpose-built transducers and electronics and is finding ever wider applications, particularly in the characterization of composite laminates.
Air-Coupled Ultrasonics
Authors: Chimenti Dale , Rokhlin Stanislav , Nagy Peter
Published: November 2020

Ultrasonic material characterization or inspection for defects is conventionally performed using either liquid coupling (water, usually) or some type of gel or oil in contact-mode coupling. Mechanical waves can be transmitted only through some sound-supporting medium from their source (a transducer) to the object under study, and back again. Using distilled, degassed water to couple ultrasound to an object under test works quite well and has many technical advantages, including relatively low signal loss over laboratory or shop dimensions at typical frequencies, almost zero toxicity, and low cost. For many applications, the use of water is acceptable and preferred. There are, however, certain testing applications for which water can be a disadvantage. These situations include materials that are sensitive to contact with water, such as uncured graphite-epoxy composites or certain electronics. Large objects, whose total immersion is impractical, or objects for which rapid scanning is required might also be unsuitable for water coupling. Recent technological developments are beginning to permit the judicious replacement of water by a far more ubiquitous sound coupling medium—air. Ultrasonic testing in air has been investigated for more than 30 years, but recently there has been an upsurge in interest and application because of the availability of much more efficient sound-generating devices designed specifically for operation in air. In water- or direct-coupled ultrasonics, one typically employs piezoelectric transducers to generate sound waves because they are well suited to the generation of sound in water or in solids because of their high acoustic impedance. In air, however, we need just the opposite. Air is very compliant, so waves from a high-impedance source couple poorly into air. Much effort has been invested in finding suitable impedance matching materials that will render the familiar piezoelectric probe efficient in air-coupled (A-C) ultrasound. The problem, however, is nearly insurmountable because of the large acoustic impedance difference between air and quartz, for example. Quartz has an acoustic impedance of about 15 MRayl, while air’s impedance is about 425 Rayl, a ratio of about 35,000. The challenge is to find a material with an acoustic impedance that nearly equals the geometric average of these two widely disparate values.
Sinc Approximation
Authors: Kowalski Marek A. , Sikorski Krzystof A. , Stenger Frank
Published: November 2020

Sine methods are a new family of self-contained methods of approximation, which have several advantages over classical methods of approximation in the case of the presence of end-point singularities, in the case when we have a semi-infinite or infinite interval of approximation, or in the case of the presence of a boundary layer situation.
Moment Problems
Authors: Kowalski Marek A. , Sikorski Krzystof A. , Stenger Frank
Published: November 2020

In this chapter we present the classical moment problems as they have been mathematically defined. Moment problems are the simplest way to describe inverse problems mathematically. These problems were originally posed with moments being integrals of monomials. Such moment problems are ill-posed, and present considerable computational difficulty. On the other hand, moment problems whose moments are integrals of orthogonal bases can computationally be dealt with much more easily.
Prerequisites
Authors: Smullyan Raymond M
Published: November 2020

As we remarked in the preface, although this volume is a sequel to our earlier volume G.I.T. (Gödel’s Incompleteness Theorems), it can be read independently by those readers familiar with at least one proof of Gödel’s first incompleteness theorem. In this chapter we give the notation, terminology and main results of G.I.T. that are needed for this volume. Readers familiar with G.I.T. can skip this chapter or perhaps glance through it briefly as a refresher. §0. Preliminaries. we assume the reader to be familiar with the basic notions of first-order logic—the logical connectives, quantifiers, terms, formulas, free and bound occurrences of variables, the notion of interpretations (or models), truth under an interpretation, logical validity (truth under all interpretations), provability (in some complete system of first-order logic with identity) and its equivalence to logical validity (Gödel’s completeness theorem). we let S be a system (theory) couched in the language of first-order logic with identity and with predicate and/or function symbols and with names for the natural numbers. A system S is usually presented by taking some standard axiomatization of first-order logic with identity and adding other axioms called the non-logical axioms of S.we associate with each natural number n an expression n̅ of S called the numeral designating n (or the name of n).we could, for example, take 0̅, 1̅, 2̅, . . . ,to be the expressions 0,0', 0",..., as we did in G.I.T. we have our individual variables arranged in some fixed infinite sequence v1, v2,..., vn , . . . . By F(v1, ..., vn) we mean any formula whose free variables are all among v1,... ,vn, and for any (natural) numbers k1,...,kn by F(к̅1 ,... к̅n), we mean the result of substituting the numerals к̅1 ,... к̅n, for all free occurrences of v1,... ,vn in F respectively.
Indexing
Authors: Smullyan Raymond M
Published: November 2020

For the remaining chapters, we will need two basic theorems in recursive function theory—the enumeration theorem of Kleene and Post and the iteration theorem of Kleene. §1. Indexing. we wish to arrange all r.e. sets in an infinite sequence ω0, ω1, . . . ,ωn , . . . (allowing repetitions) in such a way that the relation xÎ ωy is r.e. we shall take the system (Q) as our basic formalism for recursive function theory. we know that (Q) is axiomatizable and that the representable sets of (Q) are precisely the r.e. sets. we define ωi - as the set of all numbers n such that Ei[ n̅ ] is provable in (Q). Equivalently, wi- is the set of all n such that r(i,n) Î P, where r(i,n) is the Gödel number of Ei[ n̅ ] and P is the set of Gödel numbers of the provable formulas of (Q). Since r(x,y) is a recursive function and P is an r.e. set, then the relation r(x,y) Î P is r.e., and this is the relation y Î ωx. Also, every r.e. set A is represented in (Q) by some formula Ei(v1); hence A = ωi. Thus every r.e. set appears in our enumeration. we call i an index of an r.e. set A if A = ωi. we let U(x,y) be the relation x Î ωy , and we see that this relation is r.e. Indexing of r.e. Relations. For each n ³ 2, we also wish to arrange all r.e. relations of degree n an in infinite sequence . . . Ron,R1n , . . . , Rnn , . . . in such a manner that the relation Ryn(x1, . . . ,xn) is an r.e. relation among x1, . . . , xn and y. To this end, it will be convenient to use the indexing of r.e. sets that we already have and to use the recursive pairing function J(x,y) and its associated functions Jn(x1,. . . ,xn) (cf. §4, Chapter 1).
Uniform Gödelization
Authors: Smullyan Raymond M
Published: November 2020

We conclude this volume with some pretty applications of recursion and double recursion theorems and some variants of Shepherdson’s arguments. We obtain a substantial strengthening of Shepherdson’s theorem as well as some new results on uniform incompletability, which we now define. Given a consistent axiomatizable system S, we let Sn be that system whose axioms are those of S together with all formulas whose Godel number is in ωn. [We might refer to Sn as the nth extension of S.] We call S uniformly incompletable if there is a formula H(v1) such that for any n for which Sn is consistent, H(n̅) is an undecidable sentence of Sn. [In a sense, for each n for which Sn is consistent, H(n̅) can be thought of as asserting its oωn non-provability in Sn— or more accurately that it is not provable in Sn before it is refutable in Sn.] Marian Pour-El [1968] proved that every consistent axiomatizable extension of (R) is uniformly incompletable (a part of her argument is a variant of the proof of the Putnam-Smullyan theorem). We have been independently working on this problem along entirely different lines which reveal that such systems possess some interesting properties apparently stronger than uniform incompletability. It is to these stronger properties that we first turn. We shall say that S has the sentential recursion property if for every r.e. relation R(x,y) there is a number h such that x : R(x,h) is represented in S by a formula H(v1) whose Godel number is h. Using the weak recursion theorem, we will prove a result that implies that every consistent axiomatizable extension of (R) has the sentential recursion property.
Intermolecular Effects: II. Constraints along Network Chains
Authors: Erman Burak , Mark James E.
Published: November 2020

In the constrained-junction model presented in chapter 3, intermolecular correlations were assumed to suppress the fluctuations of junctions. According to this model, the elastic free energy of a network varies between the free energies of the phantom and the affine networks. In a second group of models, to be introduced here, there is a constraining action of entanglements along the chains that may further contribute to the elastic free energy, as if they were additional (albeit temporary) junctions. Consequently, the upper bound of the elastic free energy of such networks may exceed that of an affine network. Since the entanglements along the chain contour are explicitly taken into account in the models, they are referred to as the constrained-chain models. The idea of constrained-chain theories originates from the trapped-entanglement concept of Langley, and Graessley, stating that some fraction of the entanglements which are present in the bulk polymer before cross-linking become permanently trapped by the cross-linking and act as additional cross-links. These trapped entanglements, unlike the chemical cross-links, have some freedom, and the two chains forming the entanglement may slide relative to one other. The two chains may therefore be regarded as being attached to each other by means of a fictitious “slip-link,” as is illustrated schematically in figure 4.1. The entangled system of chains representing the real situation is shown in part (a), and the representation of two entangled chains in this system joined together by a sliplink is shown in part (b). The slip-link may move along the chains by a distance a, which is inversely proportional to the severity of the entanglements. A model based on this picture of slip-links was first proposed by Graessley, and a more rigorous treatment of the slip-link model was given by Ball et al. and subsequently simplified by Edwards and Vilgis; section 4.1 describes this latter treatment in detail. In section 4.2, we present the extension of the Flory constrained junction model to the constrained-chain model by including the effects of constraints along chains, following Erman and Monnerie. One of the newest approaches, the diffused-constraints model, is then described briefly in section 4.3.
Model Elastomers
Authors: Erman Burak , Mark James E.
Published: November 2020

Until quite recently, there was relatively little reliable quantitative information on the relationship of stress to structure, primarily because of the uncontrolled manner in which elastomeric networks were generally prepared. Segments close together in space were linked irrespective of their locations along the chain trajectories, thus resulting in a highly random network structure in which the number and locations of the cross-links were essentially unknown. Such a structure is shown in figure 10.1. New synthetic techniques are now available, however, for the preparation of “model” polymer networks of known structure. More specifically, if networks are formed by end linking functionally terminated chains instead of haphazardly joining chain segments at random, then the nature of this very specific chemical reaction provides the desired structural information. Thus, the functionality of the cross links is the same as that of the end-linking agent, and the molecular weight Mc between cross-links and the molecular weight distribution are the same as those of the starting chains prior to their being end-linked. An example is the reaction shown in figure 10.2, in which hydroxyl-terminated chains of poly(dimethylsiloxane) (PDMS) are end-linked using tetraethyl orthosilicate. Characterizing the un-cross-linked chains with respect to molecular weight Mn and molecular weight distribution, and then carrying out the specified reaction to completion, gives elastomers in which the network chains have these characteristics; in particular, a molecular weight Mc between cross-links equal to Mn, a network chain-length distribution equal to that of the starting chains, and cross-links having the functionality of the end-linking agent. It is also possible to use chains having a known number of potential cross-linking sites placed as side chains along the polymer backbone, so long as their distribution is known as well. Because of their known structures, such model elastomers are now the preferred materials for the quantitative characterization of rubberlike elasticity. Such very specific cross-linking reactions have also been shown to be useful in the preparation of liquid-crystalline elastomers. Trifunctional and tetrafunctional PDMS networks prepared in this way have been used to test the molecular theories of rubber elasticity with regard to the increase in non-affineness of the network deformation with increasing elongation.