Institute of Science and Technology

A theoretical and experimental study has been made of silicon Schottky diodes in which the metal and semiconductor are separated by a thin interfacial film. A generalized approach is taken towards the interface states which considers their communication with both the metal and the semiconductor. Diodes were fabricated with interfacial films ranging from 8 to 26 Å in thickness, and their characteristics are related to this model. The effects of reduced transmission coefficients together with fixed charge in the film are investigated. The interpretation of the current-voltage characteristics and the validity of the C−2-V method in the determination of diffusion potentials are discussed.

Journal Article International Production and the Multinational Enterprise Get access International Production and the Multinational Enterprise. By John H. DUNNING. London: George Allen and Unwin, 1981. Pp. vii+ 439. £20.00 hard­back, £8.95 paperback.) Fred Burton Fred Burton University of Manchester Institute of Science and Technology Search for other works by this author on: Oxford Academic Google Scholar The Economic Journal, Volume 92, Issue 366, 1 June 1982, Pages 434–435, https://doi.org/10.2307/2232466 Published: 01 June 1982

The Dommel-Tinney approach to the calculation of optimal power-system load flows has proved to be very powerful and general. This paper extends the problem formulation and solution scheme by incorporating exact outage-contingency constraints into the method, to give an optimal steady-state-secure system operating point. The controllable system quantities in the base-case problem (e.g. generated MW, controlled voltage magnitudes, transformer taps) are optimised within their limits according to some defined objective, so that no limit-violations on other quantities (e. g. generator MVAR and current loadings, transmission-circuit loadings, load-bus voltage magnitudes, angular displacements) occur in either the base-case or contingency-case system operating conditions.

This paper describes a simple, very reliable and extremely fast load-flow solution method with a wide range of practical application. It is attractive for accurate or approximate off-and on-line routine and contingency calculations for networks of any size, and can be implemented efficiently on computers with restrictive core-store capacities. The method is a development on other recent work employing the MW-Θ/ MVAR-V decoupling principle, and its precise algorithmic form has been determined by extensive numerical studies. The paper gives details of the method's performance on a series of practical problems of up to 1080 buses. A solution to within 0.01 MW/MVAR maximum bus mismatches is normally obtained in 4 to 7 iterations, each iteration being equal in speed to 1½ Gauss-Seidel iterations or 1/5th of a Newton iteration. Correlations of general interest between the power-mismatch convergence criterion and actual solution accuracy are obtained.

Summary The notion of a limit cycle, which can only exist in a non-linear system, plays the key role in the modelling of cyclical data. We have shown that the class of threshold autoregressive models is general enough to capture this notion, a definition of which in discrete time is proposed. The threshold value has an interesting interpretation. Simulation results are presented which demonstrate that this new class of models exhibits some well-known features of non-linear vibrations. Detailed analyses of several real data sets are discussed.

A great deal of research has been conducted over recent years in the field of occupational stress and its relationship to physical and mental illness. This paper attempts to provide a framework for examining this work, with the dual objectives of broadening the existing psychological literature with the extensive medical data available and also highlighting the research gaps in this area. By emphasizing the medical evidence it is hoped that we may encourage greater interdisciplinary work in the growing field of stress at work.

Abstract The morphology of porous anodic oxide films formed on aluminium in phosphoric acid electrolytes at constant current density or voltage, and under changing electrical or electrolytic conditions, has been studied quantitatively by electron microscopy. Replicas from film sections and from both film interfaces have been prepared, as well as transmission micrographs of thin films, produced under accurately defined conditions. During formation at constant current density, pore initiation occurs by the merging of locally thickening oxide regions, which seem related to the substructure of the substrate, and the consequent concentration of current into the residual thin areas. The pores grow in diameter and change in number until the steady-state morphology is established. The film barrier layer thickness has been measured directly for the first time. The steady-state barrier-layer thickness, cell diameter and pore diameter are all observed to be directly proportional to the formation voltage. It becomes evident that the barrier-layer thickness, decided largely by an equilibrium established between oxide formation in the barrier-layer and field-assisted dissolution (probably thermally enhanced) at the pore bases, determines the cell and pore sizes by a simple geometrical mechanism. Anion incorporation into the film and its hydrogen-bonded structure play secondary roles to these factors in determining the actual film morphology, although not its subsequent properties. A consequence of the mechanism is that, at constant current density, relatively non-aggressive electrolytes give thicker barrier layers, larger cells and larger pores next to the barrier layer than aggressive media, although subsequent pore widening at the outer surface of the film by simple chemical dissolution is more severe in aggressive electrolytes.

Synopsis A method of analysis is described for determining the factor of safety of an embankment against failure on a cylindrical slip surface. The analysis is in terms of effectivce stress and leads to two equa-tions of equilibrium, the first in respect of forces and the second in respect of moments. Using this method of analysis, the factors affecting the accuracy of Bishop's simplified method have been investigated. Charts have been obtained for three different values of the pore pressure coefficient (r u ) which identify the position of the critical slip circle. A set of stability charts is also given. On décrit une méthode d'analyse pour déterminer le facteur de sécurité d'un remblai contre la rupture sur une surface de glissement cylindrique. L'analyse est faite d'après la contrainte effective ett amène à deux équations d'équilibre, la première se rapportant aux forces et la deuxième aux moments. En utilisant cette méthod d'analyse, on a étudié les facteurs qui affectent la précision de la méthode simplifiée de Bishop. On est arrivé à des diagram-mes pour les trois valeurs différentes de coefficient de pression interstitielle (r u ) quiidentifient la position du cercle de glissement critique. On donne aussi un groupe de diagrammes de stabilité.

Cracks on the concrete surface are one of the earliest indications of degradation of the structure which is critical for the maintenance as well the continuous exposure will lead to the severe damage to the environment. Manual inspection is the acclaimed method for the crack inspection. In the manual inspection, the sketch of the crack is prepared manually, and the conditions of the irregularities are noted. Since the manual approach completely depends on the specialist’s knowledge and experience, it lacks objectivity in the quantitative analysis. So, automatic image-based crack detection is proposed as a replacement. Literature presents different techniques to automatically identify the crack and its depth using image processing techniques. In this research, a detailed survey is conducted to identify the research challenges and the achievements till in this field. Accordingly, 50 research papers are taken related to crack detection, and those research papers are reviewed. Based on the review, analysis is provided based on the image processing techniques, objectives, accuracy level, error level, and the image data sets. Finally, we present the various research issues which can be useful for the researchers to accomplish further research on the crack detection. Keywords: Crack detection, Image processing, Median filter, Segmentation, Feature extraction

We report on the population properties of compact binary mergers inferred from gravitational-wave observations of these systems during the first three LIGO-Virgo observing runs. The Gravitational-Wave Transient Catalog 3 (GWTC-3) contains signals consistent with three classes of binary mergers: binary black hole, binary neutron star, and neutron star–black hole mergers. We infer the binary neutron star merger rate to be between 10 and <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mn>1700</a:mn><a:mtext> </a:mtext><a:mtext> </a:mtext><a:msup><a:mrow><a:mi>Gpc</a:mi></a:mrow><a:mrow><a:mo>−</a:mo><a:mn>3</a:mn></a:mrow></a:msup><a:mtext> </a:mtext><a:msup><a:mrow><a:mi>yr</a:mi></a:mrow><a:mrow><a:mo>−</a:mo><a:mn>1</a:mn></a:mrow></a:msup></a:mrow></a:math> and the neutron star–black hole merger rate to be between 7.8 and <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:mn>140</c:mn><c:mtext> </c:mtext><c:mtext> </c:mtext><c:msup><c:mrow><c:mi>Gpc</c:mi></c:mrow><c:mrow><c:mo>−</c:mo><c:mn>3</c:mn></c:mrow></c:msup><c:mtext> </c:mtext><c:msup><c:mrow><c:mi>yr</c:mi></c:mrow><c:mrow><c:mo>−</c:mo><c:mn>1</c:mn></c:mrow></c:msup></c:mrow></c:math>, assuming a constant rate density in the comoving frame and taking the union of 90% credible intervals for methods used in this work. We infer the binary black hole merger rate, allowing for evolution with redshift, to be between 17.9 and <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mrow><e:mn>44</e:mn><e:mtext> </e:mtext><e:mtext> </e:mtext><e:msup><e:mrow><e:mi>Gpc</e:mi></e:mrow><e:mrow><e:mo>−</e:mo><e:mn>3</e:mn></e:mrow></e:msup><e:mtext> </e:mtext><e:msup><e:mrow><e:mi>yr</e:mi></e:mrow><e:mrow><e:mo>−</e:mo><e:mn>1</e:mn></e:mrow></e:msup></e:mrow></e:math> at a fiducial redshift (<g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mi>z</g:mi><g:mo>=</g:mo><g:mn>0.2</g:mn></g:math>). The rate of binary black hole mergers is observed to increase with redshift at a rate proportional to <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mo stretchy="false">(</i:mo><i:mn>1</i:mn><i:mo>+</i:mo><i:mi>z</i:mi><i:msup><i:mo stretchy="false">)</i:mo><i:mi>κ</i:mi></i:msup></i:math> with <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:mi>κ</m:mi><m:mo>=</m:mo><m:mn>2.</m:mn><m:msubsup><m:mn>9</m:mn><m:mrow><m:mo>−</m:mo><m:mn>1.8</m:mn></m:mrow><m:mrow><m:mo>+</m:mo><m:mn>1.7</m:mn></m:mrow></m:msubsup></m:math> for <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mi>z</o:mi><o:mo>≲</o:mo><o:mn>1</o:mn></o:math>. Using both binary neutron star and neutron star–black hole binaries, we obtain a broad, relatively flat neutron star mass distribution extending from <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"><q:msubsup><q:mn>1.2</q:mn><q:mrow><q:mo>−</q:mo><q:mn>0.2</q:mn></q:mrow><q:mrow><q:mo>+</q:mo><q:mn>0.1</q:mn></q:mrow></q:msubsup></q:math> to <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" display="inline"><s:msubsup><s:mn>2.0</s:mn><s:mrow><s:mo>−</s:mo><s:mn>0.3</s:mn></s:mrow><s:mrow><s:mo>+</s:mo><s:mn>0.3</s:mn></s:mrow></s:msubsup><s:msub><s:mi>M</s:mi><s:mo stretchy="false">⊙</s:mo></s:msub></s:math>. We confidently determine that the merger rate as a function of mass sharply declines after the expected maximum neutron star mass, but cannot yet confirm or rule out the existence of a lower mass gap between neutron stars and black holes. We also find the binary black hole mass distribution has localized over- and underdensities relative to a power-law distribution, with peaks emerging at chirp masses of <v:math xmlns:v="http://www.w3.org/1998/Math/MathML" display="inline"><v:msubsup><v:mn>8.3</v:mn><v:mrow><v:mo>−</v:mo><v:mn>0.5</v:mn></v:mrow><v:mrow><v:mo>+</v:mo><v:mn>0.3</v:mn></v:mrow></v:msubsup></v:math> and <x:math xmlns:x="http://www.w3.org/1998/Math/MathML" display="inline"><x:msubsup><x:mn>27.9</x:mn><x:mrow><x:mo>−</x:mo><x:mn>1.8</x:mn></x:mrow><x:mrow><x:mo>+</x:mo><x:mn>1.9</x:mn></x:mrow></x:msubsup><x:msub><x:mi>M</x:mi><x:mo stretchy="false">⊙</x:mo></x:msub></x:math>. While we continue to find that the mass distribution of a binary’s more massive component strongly decreases as a function of primary mass, we observe no evidence of a strongly suppressed merger rate above approximately <ab:math xmlns:ab="http://www.w3.org/1998/Math/MathML" display="inline"><ab:mn>60</ab:mn><ab:msub><ab:mi>M</ab:mi><ab:mo stretchy="false">⊙</ab:mo></ab:msub></ab:math>, which would indicate the presence of a upper mass gap. Observed black hole spins are small, with half of spin magnitudes below <db:math xmlns:db="http://www.w3.org/1998/Math/MathML" display="inline"><db:msub><db:mi>χ</db:mi><db:mi>i</db:mi></db:msub><db:mo>≈</db:mo><db:mn>0.25</db:mn></db:math>. While the majority of spins are preferentially aligned with the orbital angular momentum, we infer evidence of antialigned spins among the binary population. We observe an increase in spin magnitude for systems with more unequal-mass ratio. We also observe evidence of misalignment of spins relative to the orbital angular momentum. Published by the American Physical Society 2023

A review of <i>Quantum Theory of Finite Systems</i>, by J. P. BLAIZOT and<br/>GEORGES RIPKA. (The MIT Press.) [Pp. xviii + 655.1 £44.95.

Research using a refinement of existing measures of mood, the UWIST Mood Adjective Checklist (UMACL), is reviewed. A factor analysis ( N = 388), using a validated criterion for assessing the number of factors to be extracted, confirmed that the UMACL measures dimensions of energetic arousal, tense arousal and hedonic tone. Psychometric properties of UMACL scales were satisfactory. Discriminant validity was established by showing that correlations between UMACL scales and demographic and personality variables were small in magnitude, though of theoretical importance. Significant correlations between the arousal scales and psychophysiological measures of autonomic arousal demonstrate concurrent validity. A series of studies shows that the UMACL scales are sensitive to external ‘stressors’. Specific influences on each of the three principal scales have been found. Certain stressors appear to evoke a more general stress syndrome associated with reduced energetic arousal and hedonic tone, and increased tense arousal.

Molecular dynamics simulations have evolved into a mature technique that can be used effectively to understand macromolecular structure-to-function relationships. Present simulation times are close to biologically relevant ones. Information gathered about the dynamic properties of macromolecules is rich enough to shift the usual paradigm of structural bioinformatics from studying single structures to analyze conformational ensembles. Here, we describe the foundations of molecular dynamics and the improvements made in the direction of getting such ensemble. Specific application of the technique to three main issues (allosteric regulation, docking, and structure refinement) is discussed.

The sorptivity is an easily measured material property which characterizes the tendency of a porous material to absorb and transmit water by capillarity. Its theoretical basis in unsaturated flow theory is reviewed, together with methods of measurement suitable for cement-based materials. Available data on mortars and concretes are included. The dependence of the sorptivity on initial water content, temperature and fluid properties is also described. Other test methods (the initial surface absorption, the Figg water absorption and the Covercrete absorption tests) are discussed in terms of the sorptivity.

Synopsis A method of analysis is described for determining the factor of safety of an embankment against failure on a cylindrical slip surface. The analysis is in terms of effectivce stress and leads to two equa-tions of equilibrium, the first in respect of forces and the second in respect of moments. Using this method of analysis, the factors affecting the accuracy of Bishop's simplified method have been investigated. Charts have been obtained for three different values of the pore pressure coefficient (ru) which identify the position of the critical slip circle. A set of stability charts is also given. On decrit une methode d'analyse pour determiner le facteur de securite d'un remblai contre la rupture sur une surface de glissement cylindrique. L'analyse est faite d'apres la contrainte effective ett amene a deux equations d'equilibre, la premiere se rapportant aux forces et la deuxieme aux moments. En utilisant cette method d'analyse, on a etudie les facteurs qui affectent la precision de la methode sim...

Cognitive Theory and Models of Anxiety: An Introduction. Assessment: An Overview. Cognitive Therapy: Basic Characteristics. Cognitive Therapy: Basic Techniques. Panic Disorder. Hypochondriasis: Health Anxiety. Social Phobia. Generalised Anxiety Disorder. Obsessive-Compulsive Disorder. Future Developments in Cognitive Therapy. Rating Scales. Appendix. References. Index.

The article reconceptualizes the meaning of emancipation in management and organization studies and develops an approach that (a) takes into account recent criticism of its “totalizing” tendencies raised by post structuralists and (b) makes it more sensitive to the particularities of—and thereby more relevant for—management studies. The first part of the article reviews and discusses tendencies in critical theory toward negativism, essentialism, and intellectualism. The second part reformulates the grand enterprise of emancipation into a more modest project, scaled down in terms of scope and ambition. The third part discusses ways of advancing this protect in terms of listening, writing, and reading.

This book originates from graduate courses given in Cambridge and London. It provides a brisk, thorough treatment of the foundations of algebraic number theory, and builds on that to introduce more advanced ideas. Throughout, the authors emphasise the systematic development of techniques for the explicit calculation of the basic invariants, such as rings of integers, class groups, and units. Moreover they combine, at each stage of development, theory with explicit computations and applications, and provide motivation in terms of classical number-theoretic problems. A number of special topics are included that can be treated at this level but can usually only be found in research monographs or original papers, for instance: module theory of Dedekind domains; tame and wild ramifications; Gauss series and Gauss periods; binary quadratic forms; and Brauer relations. This is the only textbook at this level which combines clean, modern algebraic techniques together with a substantial arithmetic content. It will be indispensable for all practising and would-be algebraic number theorists.

This paper summarizes the results of a research project analyzing communication about global warming among those in the fields of science, politics, and the media in Germany between 1975 and 1995. The methodology of discourse analysis has been applied to investigate the changing perceptions of climate change over time and the ways in which it became an important issue on Germany's political agenda. The first part of the paper will briefly introduce the underlying theoretical assumptions and explain the multiple steps by which data covering a period of two decades have been collected and analyzed. In the second part, the paper will provide the reader with the main research results, indicating the usefulness of distinguishing among the separate discourses on climate change in science, politics, and the mass media. The results suggest that there are specific discourse dynamics common to each of the three spheres, as well as some important disparities among them. These findings will be illustrated by a selection of examples typical of the samples analyzed. Finally, the third part of the paper will discuss the broader theoretical and practical implications of these results, which suggest that modern societies must cope not only with environmental risks but also with the risks inherent in communication.

Abstract A new model is proposed to describe the large recoverable extensions which can be observed with high polymers below their glass transition points. The model consists of a Hookean spring in series with an Eyring dashpot and rubber elasticity spring in parallel. Conventional stress-strain curves for cellulose nitrate and cellulose acetate sheet and PVC are compared with those predicted by the model. In this way many of the characteristic features of the stress-strain curves of plastics can be illustrated. Differences between the stress-strain curves of a number of polymers are discussed in terms of the model, and the tendency of a polymer to show necking is related to the ultimate network strain (limiting elongation) under the conditions of the test.