摘要:

Sediment patterns on the ocean floor of the continental shelf can be studied using ultrasonic sonar systems, in which the geophysical patterns are mapped on a permanent paper record. Housed within a streamlined fish-like towed body, a transmitter sends an ultrasonic acoustic beam towards the sea bed, illuminating a path of the sea floor of width 1 km parallel to the track of the ship. The strength of the echo reverberation signals increases progressively through the sediment series soft mud, sands, cobbles, rocks and corals, so some measure of sediment identification is possible.

ISSN:0010-7514    

DOI:10.1080/00107516808205816

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Technological progress has required the development of new or improved materials which in turn have necessitated new techniques for their fabrication. The physicist has contributed largely to the successful application of the newer processes such as hydrostatic forming which offers significant advantages in the cold extrusion, upsetting, bulging, etc., of the more difficult and brittle materials, explosive forming which permits the economical production of large and complex shapes, and electrohydraulic and magnetic forming which can facilitate the manufacture of small but complex parts from sheet and tube. The rapid acceleration, by the sudden expansion of gases, of the moving parts of more conventional type machines has been exploited in a number of forming applications. The scope and limitations of these processes are briefly indicated. The application of ultrasonic vibration is said to facilitate the forming of certain metals by reducing the frictional forces and this aspect is receiving increasing attention.

ISSN:0010-7514    

DOI:10.1080/00107516808205817

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The properties of a thin film which cause its magnetic behaviour to differ from that of bulk material are first explained. The hysteresis loops are shown to be characteristic of a uniaxial magnetic anisotropy, and the origin of that anisotropy is briefly discussed. Deviations from the theoretically ideal behaviour of a uniaxial film are explained in terms of inhomogeneity of film structure. Some of the different kinds of domain walls observed in films are described and illustrated. The thickness dependence of the saturation magnetization is shown to be relevant to the theory of ferromagnetism in metals, and resonance phenomena are discussed in the same light. Finally the preparation of magnetic films and their practical applications are considered.

ISSN:0010-7514    

DOI:10.1080/00107516808205818

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107516808205819

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107516808205820

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107516808205821

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Niels Bohr, The Man and the Scientist. By Ruth Moore. (Hodder & Stoughton, 1967.) [Pp.xi+436.] 42s.

ISSN:0010-7514    

DOI:10.1080/00107516808205822

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107516808205823

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor