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161.
This paper presents an efficient methodology for computing constant‐ductility inelastic response spectra. The computation of constant‐ductility spectra involves numerical root‐finding algorithms to find the strongest structure providing a desired ductility response. Smooth inelastic structural behavior is modeled using a first‐order nonlinear differential equation and the transient structural response is solved using an implicit algorithm requiring Newton iterations at each time step. For structural models with smooth hysteretic behavior (not piece‐wise linear), a simple root‐finding method involving a combination of hyperbolic fits, linear interpolation, and Newton's method converges upon the highest strength (conservative) solution with a small number of iterations. The effect of the hysteretic smoothness on the occurrence of multiple roots is examined for two near‐fault and two far‐fault earthquake records, and for two measures of ductility and for normalized hysteretic energy. The results indicate how the smoothness of the hysteretic behavior affects ductility demand and constant‐ductility response spectra. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
162.
E.?S.?KazakEmail author E.?G.?Kalitina N.?A.?Kharitonova G.?A.?Chelnokov E.?V.?Elovskii I.?V.?Bragin 《Moscow University Geology Bulletin》2018,73(3):287-294
This paper reports the results of the experimental determination of the coefficient of sorption of rare-earth elements and yttrium (REY) under conditions of acidic pH using several strains of heterotrophic bacteria (Microbacterium sp., Curtobacterium sp., Bacillus subtilis, Pseudomonas putida, and Bacillus pumilis) that are widespread in natural and technogenic waters of the Far East (Russia). Insignificant fractionation between heavy and light rare-earth elements, negative cerium and dysprosium anomalies, and a positive europium anomaly were revealed. The selectivity of REY biosorption by gram-positive and gram-negative bacteria, as well as inertia of the biosorption process under more acidic conditions of the medium, were shown. 相似文献
163.
O. V. Ilyina N. S. Tychkov A. M. Agashev A. V. Golovin A. E. Izokh O. A. Kozmenko N. P. Pokhilenko 《Doklady Earth Sciences》2016,467(2):408-411
The results of the first study of the PGE distribution in deformed lherzolites of the Udachnaya kimberlite pipe (Yakutia) are presented here. The complex character of evolution of the PGE composition in the Deformed lherzolites is assumed to be the result of silicate metasomatism. At the first stage, growth in the amount of clinopyroxene and garnet in the rock is accompanied by a decrease in the concentration of the compatible PGE (Os, Ir). During the final stage, the rock is enriched with incompatible PGE (Pt, Pd) and Re possible due to precipitation of submicron-sized particles of sulfides in the interstitial space of these mantle rocks. 相似文献
164.
M.?B.?BellEmail author L.?W.?Avery J.?M.?MacLeod J.?P.?Vallée 《Astrophysics and Space Science》2011,333(2):377-388
Sensitive spectral observations made in two frequency bands near 6.0 and 17.6 GHz are described for Orion and W51. Using frequency
switching we were able to achieve a dynamic range in excess of 10,000 without fitting sinusoidal or polynomial baselines.
This enabled us to detect lines as weak as T
A
∼1 mK in these strong continuum sources. Hydrogen recombination lines with Δn as high as 25 have been detected in Orion. In the Orion data, where the lines are stronger, we have also detected a systematic
shift in the line center frequencies proportional to linewidth that cannot be explained by normal optical depth effects. 相似文献
165.
166.
Study of the material composition of Fe-Mn crusts from submarine rises in the central part of the Sea of Japan, with modern
precision methods applied, has yielded a high (up to 854 g/t) concentration of gallium contained in sorbed form. The new data
obtained have allowed a new genetic type of gallium deposits—hydrothermal-sedimentary—to be distinguished. 相似文献
167.
The population and distribution of carbon-oxidizing and sulfate-reducing bacteria in the soils of the Mozhaisk Reservoir are studied. 相似文献
168.
Impact of Earth radiation pressure on GPS position estimates 总被引:2,自引:8,他引:2
C. J. Rodriguez-Solano U. Hugentobler P. Steigenberger S. Lutz 《Journal of Geodesy》2012,86(5):309-317
GPS satellite orbits available from the International GNSS Service (IGS) show a consistent radial bias of up to several cm
and a particular pattern in the Satellite Laser Ranging (SLR) residuals, which are suggested to be related to radiation pressure
mismodeling. In addition, orbit-related frequencies were identified in geodetic time series such as apparent geocenter motion
and station displacements derived from GPS tracking data. A potential solution to these discrepancies is the inclusion of
Earth radiation pressure (visible and infrared) modeling in the orbit determination process. This is currently not yet considered
by all analysis centers contributing to the IGS final orbits. The acceleration, accounting for Earth radiation and satellite
models, is introduced in this paper in the computation of a global GPS network (around 200 IGS sites) adopting the analysis
strategies from the Center for Orbit Determination in Europe (CODE). Two solutions covering 9 years (2000–2008) with and without
Earth radiation pressure were computed and form the basis for this study. In previous studies, it has been shown that Earth
radiation pressure has a non-negligible effect on the GPS orbits, mainly in the radial component. In this paper, the effect
on the along-track and cross-track components is studied in more detail. Also in this paper, it is shown that Earth radiation
pressure leads to a change in the estimates of GPS ground station positions, which is systematic over large regions of the
Earth. This observed “deformation” of the Earth is towards North–South and with large scale patterns that repeat six times
per GPS draconitic year (350 days), reaching a magnitude of up to 1 mm. The impact of Earth radiation pressure on the geocenter
and length of day estimates was also investigated, but the effect is found to be less significant as compared to the orbits
and position estimates. 相似文献
169.
Models of surface energy balance and snow metamorphism are utilized to predict the energy and meltwater fluxes at an Arctic site in the forest–tundra transition zone of north-western Canada. The surface energy balance during the melt period is modelled using an hourly bulk aerodynamic approach. Once a snowcover becomes patchy, advection from the bare patches to the snow-covered areas results in a large spatial variation in basin snowmelt. In order to illustrate the importance of small-scale, horizontal advection, a simple parameterization scheme using sensible heat fluxes from snow free areas was tested. This scheme estimates the maximum horizontal advection of sensible heat from the bare patches to the snow-covered areas. Calculated melt was routed through the measured snowcover in each landscape type using a variable flow path, meltwater percolation model. This allowed the determination of the spatial variability in the timing and magnitude of meltwater release for runoff. Model results indicate that the initial release of meltwater first occurred on the shallow upland tundra sites, but meltwater release did not occur until nearly two weeks later on the deep drift snowcovers. During these early periods of melt, not all meltwater is available for runoff. Instead, there is a period when some snowpacks are only partially contributing to runoff, and the spatial variation of runoff contribution corresponds to landscape type. Comparisons of melt with and without advection suggests that advection is an important process controlling the timing of basin snowmelt. 相似文献
170.
Summary Much literature has reported on the concept of increased surface temperature variability during cool periods, although analyses
on temperature records have rendered inconsistent results. In addition, temperature variability during transition periods
has been rarely investigated. This study examines temperature variability during wintertime cooling (1947–1977) and warming
(1978–1992) periods for the conterminous United States to determine both whether temperature variability is different during
warming or cooling periods, and whether the change in variability is supported by midtropospheric circulation conditions.
Our results indicate that regions with high temperature variability are mostly found below the troughs in the midtropospheric
pressure fields. The direction of change in temperature variability corresponding to cooling or warming conditions, however,
varied spatially. For the southeastern and northeastern United States, winter temperatures were more variable during the cooling
period than during the warming period, while the northern and central Great Plains had greater temperature variability during
the warming period than the cooling period. Similar spatial patterns are also found for the changes in the variability of
geopotential height fields. Such spatial patterns in the temperature and height variability during warming and cooling periods
may be related to the dominant midtropospheric circulation patterns, such as the different phases of the Pacific-North American
teleconnection pattern, and the El Ni?o/Southern Oscillation events. It is concluded that the response of interannual temperature
variability to climatic changes is determined by the variation in circulation patterns, and therefore, not spatially uniform.
Received September 26, 1996 Revised April 2, 1998 相似文献