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1

Digitale Medien

Formation of secondary iron-sulphur phases during the growth of polycrystalline iron pyrite (FeS2) thin films by MOCVD (1998)

Thomas, B. ; Cibik, T. ; Höpfner, C. ; [weitere]

Springer

Journal of materials science 9 (1998), S. 61-64

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ISSN: 1573-482X

Quelle: Springer Online Journal Archives 1860-2000

Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Maschinenbau

Notizen: Abstract Thin films of iron pyrite (FeS2) have been prepared on glass and glassy carbon substrates by low pressure metal organic chemical vapour deposition (LP-MOCVD) using iron pentacarbonyl (Fe(CO)5) and di-tert.-butyldisulphide (TBDS) as precursors. The TBDS partial pressure was varied from 1 to 100 Pa for different iron pentacarbonyl partial pressures (0.25, 0.5 and 1 Pa) while all other parameters were maintained constant. It was found that there is a critical TBDS-partial pressure of about 30 Pa for a deposition temperature of 475 °C, where a drastic change in the layer properties occurs. Below this TBDS partial pressure pyrrhotite type phases (Fe1-xS) will be formed although there is a sulphur precursor excess in the gas phase. If the layers contain pyrrhotite, the electrical properties of the FeSx-films are changed significantly. The occurrence of the pyrrhotite phases does not depend on the growth rate, hence it is not controlled kinetically. Therefore, the sulphur pressure above the growing pyrite film is the important parameter controlling the solid phase. The present investigation shows that, in order to prepare pyrite thin films of good electronic quality, one has to take care to avoid the secondary sulphur-iron phases even in very small concentrations.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1008943203807

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2

Digitale Medien

Preface (1995)

Chen, Kang Ping ; Gatski, Thomas B.

Springer

Theoretical and computational fluid dynamics 7 (1995), S. 425-425

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ISSN: 1432-2250

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau , Physik

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00418139

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3

Digitale Medien

Dedication (1995)

Chen, Kang Ping ; Gatski, Thomas B.

Springer

Theoretical and computational fluid dynamics 7 (1995), S. 427-428

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ISSN: 1432-2250

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau , Physik

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00418140

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4

Digitale Medien

Predicting Noninertial Effects with Linear and Nonlinear Eddy-Viscosity, and Algebraic Stress Models (1998)

Jongen, Thibauld ; Machiels, Luc ; Gatski, Thomas B.

Springer

Flow, turbulence and combustion 60 (1998), S. 215-234

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ISSN: 1573-1987

Schlagwort(e): nonlinear eddy-viscosity model ; algebraic ; noninertial effects

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau

Notizen: Abstract Three types of turbulence models which account for rotational effects in noninertial frames of reference are evaluated for the case of incompressible, fully developed rotating turbulent channel flow. The different types of models are a Coroiolis-modified eddy-viscosity model, a realizable nonlinear eddy-viscosity model, and an algebraic stress model which accounts for dissipation rate anisotropies. A direct numerical simulation of a rotating channel flow is used for the validation of the turbulence models. This simulation differs from previous studies in that significantly higher rotation numbers are investigated. Flows at these higher rotation numbers are characterized by a relaminarization on the cyclonic or suction side of the channel, and a linear velocity profile on the anticyclonic or pressure side of the channel. The predictive performance of the three types of models are examined in detail, and formulation deficiencies are identified which cause poor predictive performance for some of the models. Criteria are identified which allow for accurate prediction of such flows by algebraic stress models and their corresponding Reynolds stress formulations.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009947620019

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5

Digitale Medien

The policy implementation process (1973)

Smith, Thomas B.

Springer

Policy sciences 4 (1973), S. 197-209

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ISSN: 1573-0891

Quelle: Springer Online Journal Archives 1860-2000

Thema: Politikwissenschaft , Wirtschaftswissenschaften

Notizen: Abstract There is an implicit assumption in most policy studies that once a policy has been formulated the policy will be implemented. This assumption is invalid for policies formulated in many Third World nations and for types of policies in Western societies. Third World governments tend to formulate broad, sweeping policies, and governmental bureaucracies often lack the capacity for implementation. Interest groups, opposition parties, and affected individuals and groups often attempt to influence the implementation of policy rather than the formulation of policy. A model of the policy implementation process is presented. Policy implementation is seen as a tension generating force in society. Tensions are generated between and within four components of the implementing process: idealized policy, implementing organization, target group, and environmental factors. The tensions result in transaction patterns which may or may not match the expectations of outcome of the policy formulators. The transaction patterns may become crystallized into institutions. Both the transaction patterns and the institutions may generate tensions which, by feedback to the policymakers and implementors, may support or reject further implementation of the policy. By application of the model, policymakers can attempt to minimize disruptive tensions which can result in the failure of policy outcomes to match policy expectations.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01405732

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6

Digitale Medien

Policy roles: an analysis of policy formulators and policy implementors (1973)

Smith, Thomas B.

Springer

Policy sciences 4 (1973), S. 297-307

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ISSN: 1573-0891

Quelle: Springer Online Journal Archives 1860-2000

Thema: Politikwissenschaft , Wirtschaftswissenschaften

Notizen: Abstract This paper presents an empirical analysis of individuals in policy formulating and policy implementing roles. Data for the comparison are from interviews with a random sample of 119 New Zealand middle-level public administrators from 27 government departments. The individuals in the policy formulating roles were slightly younger; however, those in the formulating and implementing roles varied little from each other in terms of social background, educational attainment and career patterns. Few differences were evident in regard to job satisfaction, decisional authority, and hierarchical relations. Significant differences between policy formulators and policy implementors were discovered in terms of work load, career aspirations, and awareness of political influences in governmental policymaking. From the evidence of this study, the New Zealand administrative system does not allocate policy formulating roles to individuals different from those who implement policies. Differences between formulators and implementors in the New Zealand system appear to stem from the nature of the work of the two policy roles.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01435126

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7

Digitale Medien

Perimeter Exploration of Linear Chains of Circles (1995)

Surowiec, Charles M. ; Jones, Thomas B.

Weinheim : Wiley-Blackwell

Particle and Particle Systems Characterization 12 (1995), S. 257-263

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ISSN: 0934-0866

Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Maschinenbau , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Perimeter data, obtained from structured walks performed upon straight chains of circles and displayed in Richardson plots, reveal two distinct classes of discontinuities: textural and structural. Textural discontinuities contain information about the surface features of the profile, while structural discontinuities reveal the profile's overall shape. The origins of both types of discontinuities have easy explanations. The highly predictable behavior of the structural discontinuities serves as the basis of a newly proposed method of analysis for perimeter data. The number of structural discontinuities is equal to N, the number of circles in the chain; furthermore, the value of the step size \documentclass{article}\pagestyle{empty}\begin{document}$ \underline {\lambda} $\end{document} * associated with the first structural discontinuity is inversely related to N. These properties seem is be retained when the circles slightly intersect and also when the circles vary in diameter. Analysis of the structural discontinuities may provide a new method suitable for automated examination of chain-like agglomerate particles.

Zusätzliches Material: 10 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/ppsc.19950120508

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8

Digitale Medien

A new approach to chemical characterization of polymer surfaces (1995)

Lloyd, Thomas B. ; Ferretti, Kathleen E. ; Lagow, Joyce

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 58 (1995), S. 291-296

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ISSN: 0021-8995

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: The “three-liquid” contact angle procedure of Good et al. was applied to polymer films of varying Lewis acidic and basic nature to test the procedure. Surface energy parameters with the units of mJ/m2 are determined for the surfaces. These are γLWs (Lifshitz-van der Waals or apolar), γ+s (acidic), and γ-s (basic). Very little has yet been published on this new method, and this study found it to be promising. More research on the procedure is warranted. The study included films of basic polymethylmethacrylate (PMMA), and predominately acidic chlorinated polyvinylchloride (CPVC) and polyvinylfluoride (PVF) as well as the series: polyethylene (PE) and PE copolymerized with 1.8% and 7.0% acrylic acid. In some of the experiments receding contact angles were measured, and the surface energy parameters determined in order to cast more light on the mechanism of contact angle hysteresis. © 1995 John Wiley & Sons, Inc.

Zusätzliches Material: 6 Tab.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/app.1995.070580208

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9

Digitale Medien

Numerical calculations of three-dimensional turbulent vortex breakdown (1995)

Spall, Robert E. ; Gatski, Thomas B.

Chichester : Wiley-Blackwell

International Journal for Numerical Methods in Fluids 20 (1995), S. 307-318

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ISSN: 0271-2091

Schlagwort(e): vortex breakdown ; turbulence ; computational fluid dynamics ; Engineering ; Engineering General

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Maschinenbau

Notizen: Numerical solutions to the three-dimensional, unsteady, incompressible Reynolds-averaged Navier-Stokes equations have been obtained for bubble-type vortex breakdown. Two different turbulence models were employed: (1) standard K-ε and (2) an explicit, regularized algebraic Reynolds stress model. Results are computed at a Reynolds number of 10,000. The algebraic Reynolds stress model produced a breakdown bubble with a larger length-to-diameter ratio than did the K-ε model. Breakdown also occurred at lower levels of adverse pressure gradient for the algebraic stress model than for the K-ε model. In each case single-cell breakdown structures resulted. This is contrasted with numerical calculations for laminar breakdown which reveal the existence of complex multicell bubble breakdown structures.

Zusätzliches Material: 7 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/fld.1650200404

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