摘要:

The constancy of the laws of physics is an essential ingredient in the development of science and is implicitly assumed in the application of physics to the interpretation of astronomy and geology. This article reviews the present status of the tests of the temporal invariance of the basic interactions of physics. It reaches the conclusion that experimental tests are consistent with no time variation of the gravitational constant, but points to a fundamental difficulty in interpreting such results. The most precise tests of the temporal variation of the electromagnetic interaction together with the strong and weak nuclear forces are supplied by an analysis of neutron capture cross-sections in the spontaneous fossil nuclear reactor established in Gabon two thousand million years ago.

ISSN:0010-7514    

DOI:10.1080/00107518308210695

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

High-speed photography has the great advantage of giving direct visual information about transient processes. For this reason, it is finding increasing application for solving a range of industrial and scientific problems. This article reviews the techniques of high-speed photography and describes a range of applications. There are various types of high-speed camera which can operate in different speed, or framing rate, ranges. These are discussed in terms of increasing framing rate in frames per second (f.p.s.) which illustrates the techniques and also the historical development of the subject. The applications illustrated include studies of fracture, impact, erosion, explosive initiation and laser-induced damage.

ISSN:0010-7514    

DOI:10.1080/00107518308210696

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The field of laser processing has expanded rapidly in recent years to become one of the most prolific areas of research in applied physics. This is mainly due to the novel conditions presented by typical laser treatments which have allowed previously unexplored regimes of material processing to be readily achieved. This paper will review the present status of research in the area of laser processing of silicon in its different forms and under various conditions which offer the prospect of important advances in microelectronics fabrication, and crystal growth in general. The principal features of the more common modes of laser processing will be described, in conjuction with the widely accepted interpretations of their associated kinetics. The present controversy regarding the behaviour of silicon under intense laser excitation has stimulated much theoretical interest in the subject, and this has additionally helped to bring about a better understanding of many related physical phenomena.

ISSN:0010-7514    

DOI:10.1080/00107518308210697

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The concept of effective mass may be used to describe the motion of a nucleon in the nuclear field, at both positive and negative energies. The anomaly around the Fermi energy associated with an energy-dependent effective mass is due to increased absorption in that region. The overall energy dependence of the single-particle potential is associated with the momentum dependence of the Hartree-Fock field. The phenomenological determination of the effective mass from analyses of elastic scattering and other data is described.

ISSN:0010-7514    

DOI:10.1080/00107518308210698

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107518308210699

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107518308210700

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107518308210701

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107518308210702

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107518308210703

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Ion Implantation Techniques. Fourth International Conference, Berchtesgaden, September 1982. Edited by H. Ryssel and H. Glawischnig. (Springer-Verlag, 1982.) [Pp. xii + 372.] DM 72; $c.30-10. Scope: Conference Proceedings. Level: For specialists and postgraduates.

ISSN:0010-7514    

DOI:10.1080/00107518308210704

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor