The temperature dependence of the anisotropic secondary emission of electrons from a single crystal is determined by the relative effect of thermal scattering on the inelastic mean free path for the incident electrons...
The temperature dependence of the anisotropic secondary emission of electrons from a single crystal is determined by the relative effect of thermal scattering on the inelastic mean free path for the incident electrons, and the escape depth for the secondaries. A diffraction model for the anisotropic secondary emission based on the two-beam dynamical theory of Bethe is discussed. This model predicts a temperature dependence for the anisotropy that is qualitatively observed for a (110) surface of a tungsten single crystal. Die Temperaturabhängigkeit der anisotropen Sekundäremission von Einkristall-Oberflächen wird von der Änderung der mittleren freien Weglänge der Primärelektronen und der Diffusionslänge der Sekundärelektronen durch thermische Streuung beeinflußt. Ein Diffusionsmodell für die sekundäre Emission wird mit Hilfe der Betheschen dynamischen Theorie der Elektroneninterferenzen unter der Annahme eines Zweistrahlfalls begründet. Dieses Modell sagt die anisotrope Sekundäremission an (110)-Wolfram-Einkristalloberflächen voraus.
The world is facing major challenges for finding alternate energy sources that can satisfy the increasing demand for energy consumption while preserving the environment. The field of thermoelectrics has long...
详细信息
ISBN:
(数字)9783319963419
ISBN:
(纸本)9783319963396
The world is facing major challenges for finding alternate energy sources that can satisfy the increasing demand for energy consumption while preserving the environment. The field of thermoelectrics has long been recognized as a potential and ideal source of clean energy. However, the relatively low conversion efficiency of thermoelectric devices has prevented their utility on a large scale.;While addressing the need for thermal management in materials, device components, and systems,thermoelectrics provides a fundamental solution to waste heat recovery and temperature control.;This book summarizes the global efforts that have been made to enhance the figure of merit of various thermoelectric materials by choosing appropriate processes and their influence on properties and performance. Because of these advances, today, thermoelectric devices are found in mainstream applications such as automobiles and power generators, as opposed to just a few years ago when they could only be used in niche applications such as in aeronautics, infrared imaging, and space. However, the continued gap between fundamental theoretical results and actual experimental data of figure of merit and performance continues to challenge the commercial applications of thermoelectrics. This book presents both recent achievements and continuing challenges, and represents essential reading for researchers working in this area in universities, industry, and national labs.
The magnetocaloric effect and magnetization behavior have been analyzed in the double-perovskite Ba2FeMoO6 compound with the sintering temperature at 1273, 1373, and 1473 K. Samples were fabricated by conventional sol...
详细信息
作者：
CARRISON, D.A.SMITH, C.O.Donald A. Carrison received a B. S. degree from the University of Illinois and did graduate work in Physics
Mathematics and Engineering at the University of California at Los Angeles. He was a Staff Member in Training at the Oak Ridge School of Reactor Technology prior to joining the Director's Division at the Oak Ridge National Laboratory as a Senior Physicist with a group investigating an advanced reactor concept. Since May of 1957 he has been a member of the senior staff of Aeronutronic Systems Inc. a Ford Motor Co. subsidiary in Glendale Calif. Charles O. Smith received a B.S. in Mech. Eng. from Worcester Polytechnic Institute
a S. M. in Mech. Eng. from Massachusetts Institute of Technology and a Sc.D. in Metallurgy from Massachusetts Institute of Technology. He served in the Navy during World War II in aviation maintenance. He currently holds the rank of Lieutenant Commander USNR and is active in the reserve program of the Office of Naval Research. He has seven years teaching experience at WPI and MIT and was associated with Alcoa Research Laboratories for three and one-half years as a Research Engineer. He currently is Lecturer in Reactor Materials at the Oak Ridge School of Reactor Technology at the Oak Ridge National Laboratory.
We report dramatic improvements in both magnetostriction level and strain derivative of polycrystalline cobalt ferrite as a result of magnetic annealing. Magnetostrictive cobalt ferrite composites have potential for u...
详细信息
Rayleigh Scattering From Polystyrene SolutionsBY N. C. FORD, JR., * F. E. KARASZ t AND J. E. M. OWENDepartment of physics and Astronomy and Polymer Science and engineeringprogram, University of Massachusetts, Amherst,...
Rayleigh Scattering From Polystyrene SolutionsBY N. C. FORD, JR., * F. E. KARASZ t AND J. E. M. OWENDepartment of physics and Astronomy and Polymer Science and engineeringprogram, University of Massachusetts, Amherst, Massachusetts, 01002, *** 8th January, 1970A laser homodyne spectrometer has been used to study the power spectrum of light scattered fromdilute polystyrene+2-butanone solutions. From the measurements the translational diffusionconstants for the macromolecules were determined as a function of molecular weight and soluteconcentration. The analysis of the data included an estimation of the unperturbed dimensions of *** recent years laser homodyne spectroscopy has been applied to studies of thespectral distribution in Rayleigh light scattering from polymers in dilute ~olution.l-~The principal quantity that can be obtained from such investigations is the transla-tional diffusion constant, though in special cases the rotational diffusion constant ofanisometric polymers may be determined also.2* Compared to conventionaltechniques, the measurement of diffusion constants from light scattering studies offerscertain inherent advantages : a relatively high precision, rapid measurement times,minimal data analysis and small sample ***, because thesystem is in macroscopic equilibrium, the differential binary diffusion constant D(c)for the system (as distinct from an integral diffusion constant) is obtained *** significance of translational diffusion constants, in common with parametersobtained from other hydrodynamic measurements of macromolecules in dilutesolution, lies in their application to the characterization of such molecules in terms ofmolecular weight or size, and of *** spectroscopy studies have beenlargely confined to studies of the latter parameter, particularly with respect to thechanges in shape concomitant with conformational transitions in biological *** present study, in contrast,
Exact analytical stability criteria are derived for the coupled-core kinetics equations. Four approximate models for describing the time distribution of the coupling neutrons are considered and a theorem proved by Pon...
详细信息
Exact analytical stability criteria are derived for the coupled-core kinetics equations. Four approximate models for describing the time distribution of the coupling neutrons are considered and a theorem proved by Pontryagin is used to establish the asymptotic stability of the systems. The criterion based on the Single Delta Function Model is compared with the one based on the Single Step Function Model.
作者：
SACHS, RMTHE AUTHOR: graduated from the University of Toronto in Engineering Physics in 1948. Prior to graduation
he was active in the Royal Canadian Navy (Reserve) obtaining a commission as a sub-lieutenant (engineer). For the following eighteen years he was intimately involved in aircraft gas turbine engineering with occasional forays into the field of atomic energy industrial gas turbines and vehicular gas turbines. He has at various times specialized as a designer
a stress analyst systems analyst and development engineer. For the past four years
with United Aircraft of Canada Limited Industrial and Marine Division he was first Chief Analytical Engineer and then DDH Program Manager. During most of this time he has been involved with the application of gas turbines to marine propulsion.
Four helicopters carrying destroyers are being built for the Canadian Armed Forces incorporating an advanced all gas turbine COGOG propulsion system supplied by United Aircraft of Canada Limited. The propulsion system...
Four helicopters carrying destroyers are being built for the Canadian Armed Forces incorporating an advanced all gas turbine COGOG propulsion system supplied by United Aircraft of Canada Limited. The propulsion system installation described herein comprises two shaft lines, each with a Pratt & Whitney Aircraft FT4A-2 main engine and a Pratt & Whitney Aircraft FT12A-3 cruise engine, a reduction gearbox, propeller shaft and bearings, and a push rod actuated controllable pitch propeller. The associated ancillary systems, controls and monitoring instrumentation are described with comments on the underlying objectives and design philosophy.
We report first-principles calculations for Fe4Al11-x where 0 ≤ x ≤ 3 and for Fe4Al11-yZny for 0≤ y ≤ 1. We investigate the correlation of the magnetic and vibrational behavior with the density of states at the Fe...
详细信息
暂无评论