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
    The use of interplanetary scintillation maps in the prediction of geomagnetic activity (1996)
    Springer
    Annales geophysicae 14 (1996), S. 131-138 
    Details
    ISSN: 0992-7689
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Interplanetary scintillation (IPS), the twinkling of small angular diameter radio sources, arises from the interaction of the signal with small-scale plasma irregularities in the solar wind. The technique may be used to sense remotely the near-Earth heliosphere and has potential for tracking large-scale interplanetary disturbances from close to the Sun to the Earth. Such observations might be useful within routine geomagnetic forecasts, and we use data from the Mullard Radio Astronomy Observatory to test this suggestion. A forecast was based on the visual evaluation of each daily map. If an IPS event was observed then we proposed that any associated geomagnetic activity would occur either on that day, or during the following two days. We consider the success of these forecasts in predicting days when either an SSC/SI or an Ap value exceeding 30 were recorded. The identification of IPS events is necessarily subjective and so two observers compiled independent events lists, and the results were compared. Approximately half of the IPS events in each list were followed by a geomagnetic signature but comparison of the two lists showed that different days were being chosen. We also found that the forecasts had very high false alarm rates. Since IPS is sensitive to a volume we did not expect all events to be associated with a geomagnetic signature. However, the technique failed to forecast a large proportion of geomagnetic events and the association between IPS events and geomagnetic activity is not much better than would be expected by chance. Comparing the IPS forecasts with forecasts of Ap released by the Space Environment Services Center (SESC) we found that SESC correctly predicted a similar proportion of days when Ap\geq30, but that the performance was significantly better than would be expected by chance, and had a much lower false alarm rate. We conclude that these IPS data cannot be used alone to produce reliable geomagnetic activity forecasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-996-0131-6
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The use of various interplanetary scintillation indices within geomagnetic forecasts (1996)
    Springer
    Annales geophysicae 14 (1996), S. 139-148 
    Details
    ISSN: 0992-7689
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Interplanetary scintillation (IPS), the twinkling of small angular diameter radio sources, is caused by the interaction of the signal with small-scale plasma irregularities in the solar wind. The technique may be used to sense remotely the near-Earth heliosphere and observations of a sufficiently large number of sources may be used to track large-scale disturbances as they propagate from close to the Sun to the Earth. Therefore, such observations have potential for use within geomagnetic forecasts. We use daily data from the Mullard Radio Astronomy Observatory, made available through the World Data Centre, to test the success of geomagnetic forecasts based on IPS observations. The approach discussed here was based on the reduction of the information in a map to a single number or series of numbers. The advantages of an index of this nature are that it may be produced routinely and that it could ideally forecast both the occurrence and intensity of geomagnetic activity. We start from an index that has already been described in the literature, INDEX35. On the basis of visual examination of the data in a full skymap format modifications were made to the way in which the index was calculated. It was hoped that these would lead to an improvement in its forecasting ability. Here we assess the forecasting potential of the index using the value of the correlation coefficient between daily Ap and the IPS index, with IPS leading by 1 day. We also compare the forecast based on the IPS index with forecasts of Ap currently released by the Space Environment Services Center (SESC). Although we find that the maximum improvement achieved is small, and does not represent a significant advance in forecasting ability, the IPS forecasts at this phase of the solar cycle are of a similar quality to those made by SESC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-996-0139-y
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Development and applications of a plasma waveguide for intense laser pulses (1996)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 2149-2155 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The demonstration of optical guiding of high-intensity laser pulses in a plasma fiber waveguide [C. G. Durfee III and H. M. Milchberg, Phys. Rev. Lett. 71, 2409 (1993)] has opened the way to new advances in the development of nonlinear optics-based short-wavelength light sources, soft x-ray lasers, and compact laser-driven charged particle accelerators, and offers a new practical realm in which to study, control, and apply nonperturbative laser–matter interactions at ultrahigh intensity. An overview of selected experimental and theoretical results and their applications is presented. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871668
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    57Fe Mössbauer spectroscopic investigation of complex magnetic structures in Ga, Sc, and In substituted M-type hexagonal ferrites (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 5229-5230 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Investigation of preliminary evidence that Ga, Sc, and In influence the bulk and dynamic magnetic properties of hexagonal ferrites by means other than those supported in existing models has been undertaken. In SrFe12−xMxO19 (M=Ga, In) and BaFe12−xScxO19, the predominant 12k sublattice exhibits a remarkable splitting into two distinct subpatterns, 12k1 and 12k2: At x=0.3, hyperfine fields, Heff for 12k1 are 411, 408, and 405 kOe, respectively, and for 12k2 are 358, 339, and 311 kOe, respectively. The 12k1 hyperfine field values are virtually unchanged from that of the pure hexagonal ferrites and are independent of substitution level. Contrastingly, the abruptness of the drop in the 12k2 hyperfine field and its dependence on the nature of the substituting cation are remarkable. The relative intensity of the 12k2 component correlates with the concentration of nonmagnetic species on the 2b and 4f2 sites and with the magnetic anisotropy. Scandium seems to have a more profound influence on the magnetic structure and interactions than indium or gallium. Further, at technically significant substitution levels, Heff of the different sublattices exhibit broad and overlapping distributions of values far removed from their distinctiveness in the pure hexaferrites. Thus, the net magnetization of Ga, Sc, and In-doped hexaferrites results from a complex interplay of magnetic dilution on the 2b site, enhancement of the magnetization through substitutions on the 4f2 site, and a complex influence from the substitution-induced 12k2 sublattice. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369952
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Generation of a plasma waveguide in an elongated, high repetition rate gas jet (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 3064-3066 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We demonstrate a pulsed gas nozzle which can produce uniform, greater than 1-cm-long gas jets with peak equivalent pressures up to several hundred Torr at a distance up to ∼3 mm from the nozzle exit. Time-resolved electron density profiles are presented for 1.2-cm-long uniform plasma waveguides produced in an axicon line focus in this jet at a repetition rate of 10 Hz. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122673
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    A TECHNICAL NOTE. INFLUENCE OF MEAN STRESS ON FATIGUE IN SEVERAL ALUMINIUM ALLOYS UTILIZING Kcmax THRESHOLD PROCEDURES (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 19 (1996), S. 0 
    Details
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Recent interest in the constant Kmax (Kcmax) threshold testing procedure has resulted in a more in-depth study of the influence of Kmax level on fatigue response and ΔKth in aluminium alloys. Under Rc= 0.1 conditions, which cause large amounts of closure, ΔKth levels were typically 2 to 4 Mpam. However, under Kcmax test procedures, associated with no measurable closure at threshold, ΔKth was typically 1 Mpam. A slight Kcmax level effect on ΔKth was observed at high Kmax values for some of the alloys, and was deemed to be a pure mean stress effect, separate from closure arguments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-2695.1996.tb01029.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Methylosinus trichosporium OB3b whole-cell methane monooxygenase activity in a biphasic matrix (1996)
    Springer
    Applied microbiology and biotechnology 45 (1996), S. 658-663 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Reconstituted whole-cell preparations of lyophilized Methylosinus trichosporium OB3b were used to demonstrate soluble methane monooxygenase activity in a two-phase (biphasic) matrix consisting of a buffered aqueous phase and 2,2,4-trimethylpentane (isooctane). The rate of conversion of gaseous propylene to propylene oxide, a non-metabolized liquid, was used as the primary measure of enzyme activity. Appreciable soluble methane monooxygenase activity was detected when the volume of the aqueous phase represented at least 1% of the total volume, although the initial rate of product formation did increase as the volume of the aqueous phase increased. In comparison to the aqueous system, the specific rate and yields in the biphasic system were much less sensitive to increases in the concentrations of formate and protein (the methane monooxygenase). However, there was some evidence that the enzyme system was more stable in the biphasic matrix, since the rate of propylene oxide formation remained linear for an extended period of time. V (app.) in the biphasic system decreased by a factor of 0.6 relative to the same parameter in the aqueous system. Conversely, K m(app.) for propylene was 1.6 times greater in the biphasic system. Hence, the apparent catalytic efficiency in the aqueous system was four times that in the biphasic system, as indicated by a decrease in the corresponding ratios of V (app.) to K m(app.).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530050744
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Broken Gauge Symmetry in Macroscopic Quantum Circuits (1998)
    Springer
    Foundations of physics 28 (1998), S. 485-503 
    Details
    ISSN: 1572-9516
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this paper, we discuss the macroscopic quantum behavior of simple superconducting circuits. Starting from a Lagrangian for electromagnetic field with broken gauge symmetry, we construct a quantum circuit model for a superconducting weak link (SQUID) ring, together with the appropriate canonical commutation relations. We demonstrate that this model can be used to describe macroscopic excitations of the superconducting condensate and the localized charge states found in some ultrasmall-capacitance weak-link devices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018772229718
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Solutions of the Time-Dependent Schrödinger Equation for a Two-State System (1998)
    Springer
    Foundations of physics 28 (1998), S. 1271-1282 
    Details
    ISSN: 1572-9516
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The statistical properties of a single quantum object and an ensemble of independent such objects are considered in detail for two-level systems. Computer simulations of dynamic zero-point quantum fluctuations for a single quantum object are reported and compared with analytic solutions for the ensemble case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018822809439
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    The quantum to classical crossover for a weak link capacitor (1995)
    Springer
    Journal of low temperature physics 101 (1995), S. 1037-1054 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We consider a model weak link, an ultra-small capacitor subject to tunnelling, to ohmic dissipation and fed with an external displacement current. The framework we employ is the new approach of quantum state diffusion, which treats individual open quantum systems as well as being able to generate the conventional ensemble averages. We show how evidence for archetypal quantum behaviour (coherent oscillations) and archetypal classical behaviour (chaos) arises, for weak links whose parameters are related by a rather modest scaling. Interestingly, the quantum behaviour can arise for a weak link with intrinsic parameter values such that it could exhibit chaos, if it were a purely classical device.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00754523
    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...