A compact representation of gamma-ray burst time series     

C. A. Young  D. C. Meredith  J. M. Ryan 《Astrophysics and Space Science》1995,231(1-2):119-122

Multiscale edge detection (MSED), using wavelet transform extrema, provides a robust method to compress the information in a transient signal. We apply this to gamma-ray burst (GRB) time series. Multiscale edge detection can be used to quantify the variability, identify structures (e.g. FREDs), and suppress noise. We present preliminary results of MSED applied to BATSE 64ms discsc data.  相似文献   

Active Regions Observed in Extreme Ultraviolet Light by the Coronal Diagnostic Spectrometer on Soho     

A. Fludra  P. Brekke  R. A. Harrison  H. E. Mason  C. D. Pike  W. T. Thompson  P. R. Young 《Solar physics》1997,175(2):487-509

We present observations of five active regions made by the Coronal Diagnostic Spectrometer (CDS) on the Solar and Heliospheric Observatory (SOHO). CDS observes the Sun in the extreme ultraviolet range 150–780 Å. Examples of active region loops seen in spectral lines emitted at various temperatures are shown. Several classes of loops are identified: those that are seen in all temperatures up to 2 x 10⁶ K; loops seen at 10⁶ K but not reaching 1.6 x 10⁶ K; those at temperatures 2– 4 x 10^-5 K and occasionally at 6 x 10^-5 K but not reaching 10⁶ K. An increasing loop size with temperature and the relationship between the cool and hot structures is discussed. CDS observations reveal the existence of loops and other unresolved structures in active regions, at temperatures between 1.5– 4 x 10^-5 K, which do not have counterparts in lines emitted above 8 x 10^-5 K. Bright compact sources only seen in the transition region lines are investigated. These sources can have lifetimes of up to several days and are located in the vicinity of sunspots. We study the variability of active region sources on time scales from 30 sec to several days. We find oscillatory behaviour of Hei and Ov line intensities in an active region on time scales of 5–10 min.  相似文献   

Radiative Transfer in a Turbulent Expanding Molecular Envelope: Application to Mira     

Mercè Crosas  Karl M. Menten  Ken Young  Thomas G. Phillips 《Astrophysics and Space Science》1997,251(1-2):189-192

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Estimating aquifer hydraulic properties using sinusoidal pumping at the Savannah River site,South Carolina,USA   总被引：1，自引：0，他引：1  

Todd?C.?RasmussenEmail author  Kevin?G.?Haborak  Michael?H.?Young 《Hydrogeology Journal》2003,11(4):466-482

A framework for estimating aquifer hydraulic properties using sinusoidal pumping is presented that (1) derives analytical solutions for confined, leaky, and partially penetrating conditions; (2) compares the analytical solutions with a finite element model; (3) establishes a field protocol for conducting sinusoidal aquifer tests; and (4) estimates aquifer parameters using the analytical solutions. The procedure is demonstrated in one surficial and two confined aquifers containing potentially contaminated water in coastal plain sediments at the Savannah River site, a federal nuclear facility. The analytical solutions compare favorably with finite-element solutions, except immediately adjacent to the pumping well where the assumption of zero borehole radius is not valid. Estimated aquifer properties are consistent with previous studies for the two confined aquifers, but are inconsistent for the surficial aquifer; conventional tests yielded estimates of the specific yield—consistent with an unconfined response—while the shorter-duration sinusoidal perturbations yielded estimates of the storativity—consistent with a confined, elastic response. The approach minimizes investigation-derived wastes, a significant concern where contaminated fluids must be disposed of in an environmentally acceptable manner. An additional advantage is the ability to introduce a signal different from background perturbations, thus easing detection.  相似文献   

Environment and development in Australia     

David C. Rich  R. W. Young 《The Australian geographer》1988,19(1):7-8

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Complex P-Wave Seismograms from Simple Earthquake Sources     

A. Douglas  J. B. Young  J. A. Hudson 《Geophysical Journal International》1974,37(1):141-150

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An analysis of P-wave amplitudes recorded by seismological stations in the USSR   总被引：1，自引：1，他引：0  

P. D. Marshall  J. Bingham  J. B. Young 《Geophysical Journal International》1986,84(1):71-91

Summary. Short period P -wave amplitudes at Soviet seismic stations are analysed to determine an amplitude–distance curve in the range 0°–180° from the USSR. Station amplitude terms, corrected for crustal amplification effects, are determined from seismic sources located between 30° and 90°. A relationship between these station terms and regional P_n wave speed and regional heat flow is determined and is found to be in close agreement with similar observations in North America. Station amplitude terms were found to be reasonably uniform across the continental portion of the USSR but the Baikal Rift valley is characterized by very low P -wave amplitudes and is the most significant feature discemible from the P -wave amplitude terms.  相似文献   

Equation for the field lines of an axisymmetric magnetic multipole     

D. M. Willis  L. R. Young 《Geophysical Journal International》1987,89(3):1011-1022

Summary. An exact equation is derived for the magnetic field lines of the general axisymmetric magnetic multipole of arbitrary degree ( n ). This new result has important applications in studies of the possible nature of solarterrestrial physics during geomagnetic polarity reversals. In the limiting case of a magnetic dipole ( n=1 ), the equation for the magnetic field lines of the general axisymmetric magnetic multipole simplifies correctly to the well-known dipolar form, which is used extensively in geomagnetism, magnetospheric physics and cosmic-ray physics as a first-order approximation to the actual configuration of the geomagnetic field.
It is also shown theoretically that suites of similar magnetic field lines of the general axisymmetric multipole attain their maximum radial distances from the origin on a set of circular conical surfaces, with coincident vertices at the centre of the Earth; this set includes the equatorial plane if the degree ( n ) of the multipole is odd. The magnetic field is horizontal everywhere on all these surfaces.
Palaeomagnetic studies have suggested that during some polarity reversals the magnetic field in the inner magnetosphere can be represented approximately either by a single, non-dipolar, low-degree (2 < n < 4), axisymmetric magnetic multipole or by a linear combination of such multipoles. In this situation, the equation for the field lines of an axisymmetric magnetic multipole of low degree (2 < n < 4) would be as fundamental to a proper understanding of magnetospheric, ionospheric and cosmic-ray physics during polarity reversals as is the equation for dipolar field lines in the case of the contemporary geomagnetic field.  相似文献   

Asteroid rotation: IV. 1979 observations     

A.W. Harris  J.W. Young 《Icarus》1983,54(1):59-109

Results of photoelectric lightcurve observations made during 1979 are reported. Of a total of 53 asteroids observed, reliable rotation periods are reported for 22 asteroids for which no previous values are known, 7 periods are reported which are revisions of previously reported values, and for 12 other asteroids periods are suggested which are admittedly of low reliability and those objects should be reobserved. In addition, phase relations are presented for many of the asteroids, fitted to the theoretical phase function of Lumme and Bowell (Astron. J., 86, 1705, 1981). Adopting their formalism, mean absolute magnitudes at zero phase angle, $\text{V}\text{(0°)}$, for 52 asteroids, and values of the multiple scattering parameter, Q, for 22 asteroids are reported. For comparison purposes, the absolute magnitude, V(1,0) and the linear phase coefficient, βv, in the traditional system are computed. In the appendixes (1) the methods of observation and data reduction are discussed, which are recommended to other lightcurve observers in the hope of standardizing reporting practices as much as possible; and (2) a cumulative index of all asteroid rotation data of which the authors are aware is presented.  相似文献   

Military activities and law of the sea     

Elizabeth Young 《Marine Policy》1979,3(3):251

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