ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Gaussian packets in the computation of seismic wavefields (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 99 (1989), S. 0 
    Details
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: A method of computing synthetic seismograms by means of the three-parametric summation of Gaussian packets over space is proposed. The expansion of the wavefield specified in terms of a complex-valued amplitude and a phase function into Gaussian packets is very similar to the expansion into Gaussian beams, with the additional summation over points along the rays. Initial conditions for the wavefield, for which the initial directions of the rays are time independent (e.g. the point source), are assumed. The summation is performed in the frequency domain. The synthetic seismograms are then evaluated by the Fast Fourier transform for any source time function. The method should not require a substantial increase of the computational time with respect to the ray and Gaussian beam methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-246X.1989.tb01699.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    3-D network ray tracing (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 116 (1994), S. 0 
    Details
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: An efficient algorithm of the network shortest path calculation of rays and traveltimes of the first arrivals is described. The traveltime error of such computations is estimated. The rough estimate of the relative traveltime error is evaluated locally at all network nodes prior to network ray tracing, and is minimized by means of a proper choice of the sizes of forward stars. In this way, the structure of the network is adjusted for a particular model and for a particular computer memory. After network ray tracing, the error estimate is refined and the absolute error bounds of the calculated traveltimes are evaluated. The method and its accuracy are demonstrated on numerical examples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-246X.1994.tb03293.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Accuracy of elastic finite differences in smooth media (1996)
    Springer
    Pure and applied geophysics 148 (1996), S. 39-76 
    Details
    ISSN: 1420-9136
    Keywords: Seismic waves ; finite differences of the 2nd and 4th order ; 2-D and 3-D seismic modeling ; accuracy ; elasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The accuracy of finite-difference schemes of the 2nd and 4th order in 2-D and 3-D regular rectangular grids is studied. The method of designing the schemes and estimating their accuracy is proposed. The paper is devoted to the point schemes, expressed in terms of the discretized (point) values of the wave field and material parameters. Only the common schemes applicable in smooth parts of seismic models, outside structural interfaces, are taken into account. Finite differences at structural interfaces are studied elsewhere. The inaccuracy of finite-difference schemes is governed, above all, by the error in the phase velocity, caused by discretization. This error is estimated for several finite-difference schemes. It is explicitly dependent on the direction of propagation and on wave polarization. The maximum phase-velocity error over all directions of propagation enables the accuracy of the individual schemes to be appreciated in order to select the best one. The proposed approach is general and applicable to other finite-difference schemes, for example, of the 6th and higher orders.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00882054
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Grid travel-time tracing: Second-order method for the first arrivals in smooth media (1996)
    Springer
    Pure and applied geophysics 148 (1996), S. 539-563 
    Details
    ISSN: 1420-9136
    Keywords: Seismic waves ; first-arrival travel times ; slowness vectors ; ray tracing ; accuracy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A new computational scheme for calculating the first-arrival travel times on a rectangular grid of points is proposed. The new proposed method is of second-order accuracy. This means that the error of the calculated travel time is proportional to the second power of the grid spacing. The method should be sufficiently accurate for all applications in smooth seismic models. On the other hand, the method is not, in its present form, proposed for models with structural interfaces which make the method unstable and generate travel-time errors of the first order. Equations are also presented for the appropriate evaluation of the errors of calculated travel times to check their accuracy, and the proposed method is compared with other numerical methods. The method is developed, described and demonstrated in 2-D, but may also be extended to 3-D models and to general models with structural interfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00874578
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Preface (1996)
    Springer
    Pure and applied geophysics 148 (1996), S. 1-1 
    Details
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00882051
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Preface (1996)
    Springer
    Pure and applied geophysics 148 (1996), S. 343-343 
    Details
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00874571
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Arrival-time residuals and hypocentre mislocation (1996)
    Springer
    Pure and applied geophysics 148 (1996), S. 337-342 
    Details
    ISSN: 1420-9136
    Keywords: Hypocentre determination ; seismic model ; accuracy ; arrival-time residuals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract It is shown that the arrival-time residuals and hypocentre mislocation are two mutually independent consequences of the inaccurate seismic model and inaccurately measured arrival times. The minimum residuals resulting from the kinematic hypocentre determination contain no information on the accuracy in determining the hypocentre position.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00882066
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    The relation between Gaussian beams and Maslov asymptotic theory (1984)
    Springer
    Studia geophysica et geodaetica 28 (1984), S. 237-247 
    Details
    ISSN: 1573-1626
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Description / Table of Contents: Summary The application of Maslov asymptotic theory in a general 3-D mixed subspace of 6-D complex phase space is proposed to obtain the integral superpositions of Gaussian packets and beams. The ray method and the superposition of plane waves (Maslov method of Chapman and Drummond [7]) are special limiting cases of the above mentioned approach. The same high-frequency asymptotic expansion formulae for seismic body waves were derived previously in [8] using the Gaussian beam method.
    Notes: Резюме Прuложенuе aсuмnmоmuческоŭ mеорuu Мaсловa к общему mрехмерному смещaнному nо¶rt;nросmрaнсmву щесmuмерного фaзового nросmрaнсmвa nре¶rt;ложено ¶rt;ля nолученuя uнmегрaльных суnерnозuцuŭ Гaуссовых naкеmов u nучков. Суnерnозuцuя nлоскuх волн u лучевоŭ меmо¶rt; являюmся сnецuaльнымu nре¶rt;ельнымu случaямu nре¶rt;ложенного nо¶rt;хо¶rt;a. Те же сaмые высокочaсmоmные aсuмnmоmuческuе формулы былu рaньще nолучены меmо¶rt;ом Гaуссовых nучков [8].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01589606
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Hermite-Gaussian beams in inhomogeneous elastic media (1983)
    Springer
    Studia geophysica et geodaetica 27 (1983), S. 354-365 
    Details
    ISSN: 1573-1626
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Резюме Эрмum-Гaуссевы nучкu в mрехмерноŭ уnру оŭ нео¶rt;норо¶rt;ноŭ сре¶rt;е nолучены кaк aсuмnmоmuческuе высокочaсmоmоные решенuя урaвненuŭ ¶rt;вuженuя уnру оŭ сре¶rt;ы, сосре¶rt;оmоченные в окресmносmu лучеŭ Р u S волн. Урaвненuя ¶rt;вuженuя уnру оŭ сре¶rt;ы в эmом случaе nрuво¶rt;um к naрaболuческому урaвненuю (ур. Шре¶rt;uн ерa). Посmроены явные вырaженuя ¶rt;ля nолноŭ сuсmемы лuнеŭно-незaвuсuмых решенuŭ naрaболuческо о урaвненuя. Прu выво¶rt;е uсnользуеmся меmо¶rt; оnерamоров рож¶rt;енuя u унuчmоженuя, uзвесmныŭ uз квaнmовоŭ мехaнuкu.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01636182
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Optimization of the shape of Gaussian beams of a fixed length (1989)
    Springer
    Studia geophysica et geodaetica 33 (1989), S. 146-163 
    Details
    ISSN: 1573-1626
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Description / Table of Contents: Summary The procedure of choosing the shape of Gaussian beams in order to minimize a given object function of a certain kind is proposed. The general form of the object function enables both the average square of the quadratic variation of the phase and the average square of the beamwidth to be minimized along the central ray. The error of the transformation of the Gaussian beams at the structural interfaces may also be taken into account. Most of the hitherto published suggestions of how to choose the shape of Gaussian beams are special cases of the described procedure. The aim of this paper is not to propose the object function to be minimized, but only to describe the minimization of a given object function. The minimization assumes the a priori known lengths of the central rays of the Gaussian beams (i.e. the lengths of the beams are not free parameters in the minimization procedure).
    Notes: Резюме Пре¶rt;лaгaеmся меmо¶rt;uкa оnре¶rt;еленuя формыгaуссевых nучков, в коmороŭ мuнuмuзuруеmся ¶rt;aннaя целевaя функцuя. Точныŭ вu¶rt; целевоŭ функцuu не оnре¶rt;еляеmся, меmо¶rt;uку возможно nрuменumь ¶rt;ля шuрокого клaссa целевых функцuŭ. Общuŭ вu¶rt; целевоŭ функцuu nозволяеm, нanрuмер, мuнuмuзuровamь в¶rt;оль ценmрaльного лучa сре¶rt;нuŭ квa¶rt;рam квa¶rt;рamuчных uзмененuŭ комnлексного эŭконaлaгaуссевого nучкa u сре¶rt;нuŭ квa¶rt;рam шuрuныгaуссевого nучкa. Пре¶rt;лaгaемaя меmо¶rt;uкa nозволяеm ¶rt;aже учесmь ошuбку, вознuкaющую nрu nерехо¶rt;егaуссевого nучкa через сmрукmурaльнуюгрaнuцу рaз¶rt;елa. В меmо¶rt;uке nре¶rt;nолaгaеmся, чmо ¶rt;лuнaгaуссевого nучкa anрuорно зa¶rt;aннaя. Эmо знaчum, чmо ¶rt;лuнaгaуссевого nучкa не являеmся свобо¶rt;ным naрaмеmром в nроце¶rt;уре мuнuмuзaцuu. Большuнсmво nре¶rt;ложенных в сеŭсмологuческоŭ лumерamуре меmо¶rt;ов ¶rt;ля оnре¶rt;еленuя формыгaуссевых nучков являеmся чaсmным случaем nре¶rt;лaгaемоŭ меmо¶rt;uкu.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01646581
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...