摘要:

ABSTRACTGraticules are known for the calculation of the magnetic field of homogeneously magnetized “two‐dimensional” structures. For bodies whose lateral dimensions are comparable with the dimensions of the cross section and/or the distance between the point of observation and the structure, these graticules allow an approximative computation of the field in the plane of symmetry only. The degree of approximation can be improved by means of end corrections, but the amount of work involved increases rapidly. Moreover, even with end corrections the applicability of the graticules is still restricted to cases of rather simple geometry.In this paper, a set of graticules is proposed which already incorporates all end corrections. The set consists of three graticules, and it can be shown that at any point of observation lying outside the body each graticule needs be applied once only in order to calculate any component of the magnetic field produced by a homogeneously magnetized cylinder of arbitrary cross section, finite lateral extension and arbitrary spatial orientation.Curves and tables have been prepared, which allow the construction of the graticules under consideration. The application is illustrated by a hypothetical example. Possibilities for further improvements of the method are disc

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1964.tb01895.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

ABSTRACTUsing optimum filter theory as a starting point, we describe a method for the design of practical multi‐trace seismic data processing systems. We assume the inputs to be the superposition of signal, coherent noise, and incoherent noise. The signal and coherent noise moveouts are described statistically by their probability densities. Our approach is to split the system into two stages. The first stage achieves optimum noise suppression but distorts the signal. The signal distortion is reduced in the second stage by an optimum finite memory inverse filter.The system that is obtained using our method of design depends upon the form of the probability density functions. We show two examples, ghost suppression and velocity filtering. In ghost suppression we choose a model with moveouts known exactly, which corresponds to delta functions for the probability densities. In velocity filtering the signal and coherent noise moveouts are equally probable within non‐overlapping ranges.The resulting system in each case is both simple and effective. In ghost suppression a simple shift and subtract cancels the coherent noise. The signal distortion is reduced by an inverse filter. The velocity filter system consists of differentiated moving averages applied to each trace, followed by a 90° phase shift and a low pass fi

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1964.tb01896.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractThe paper deals with quantitative seismic measurements near underwater explosions. The blastings were carried out in an artificial small pond, the records were taken in adits, situated vertically below the charge. The range of charges extended from one detonator to 200 g of Ammon‐Gelit explosive.Conventional seismic scaling by comparing amplitude and size of charge does not yield a simple power law, the exponent being larger for smaller charges and vice versa. This result is due to the different frequency‐spectra of the seismic pulses, as shown by harmonic analysis. In contrast to this, the seismic energy as calculated from the records is directly proportional to the size of charge over the whole range.During the Lago Lagorai experiments in 1962 some quantitative seismic measurements near the shot point were also carried out. The relevant results are compared with the preceding ones and some differences are discussed.Some conclusions can be drawn:1The normal methodes, investigating the amplitude only, gives in many cases no clear description; this is especially true for nearby measurements with widely varying frequencies. Therefore it is suggested to extend conventional seismic scaling by including information on the frequency‐spectrum and the kinetic energy of the seismic signal.2In order to get clear experimental data for theoretical investigations, it is necessary to extend the recording over a half‐space, i.e. in adits or boreholes.3Influences of shape and size of the lake, in which the shots are fired, should be taken into accou

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1964.tb01897.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

ABSTRACTA graphical method of interpreting refraction data is presented based upon wave front construction in which different overburden velocity distributions can be used. The wave fronts are constructed with the aid of an Isochron Chart. By using two or more Isochron Charts, the effect of velocity variations above the refractor of interest can be allowed for.

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1964.tb01898.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

ABSTRACTBy this method an approximation of gravity‐anomaly of an inhomogeneous mass with any form is calculated. The mass is inbedded in a homogeneous medium. The density of the medium differs from the density‐distribution of the m

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1964.tb01899.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

Book Review in this Article:H. Israeland A. Krebs, Nuclear Radiation in GeophysicsB. A. Tkhostov, Initial Rock Pressures in Oil and Gas DepositsJohn S. Steinhartand Robert P. Meyer, Explosion Studies of Continental Structure

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1964.tb01900.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY