Phase-space transport in cuspy triaxial potentials: can they be used to construct self-consistent equilibria?     

Christos Siopis  Henry E. Kandrup 《Monthly notices of the Royal Astronomical Society》2000,319(1):43-62

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High-Resolution Seismic Reflection Evidence for Middle Holocene Environmental Change, Owasco Lake, New York   总被引：2，自引：0，他引：2  

Henry T. Mullins  John D. Halfman 《Quaternary Research》2001,55(3):322

Approximately 70 km of new decimeter-resolution seismic reflection profile data from Owasco Lake, New York define a middle Holocene (4600 ¹⁴C yr B.P.) erosion surface in the north end of the lake at water depths as great as 26 m. Beneath the lake, post-glacial sediments are up to 9 m thick and represent about 10% of the total sediment fill. Early to middle Holocene sediments, 6 m thick, contain biogenic gas at the south end of the basin and a large (4 km×300 m×15 m) subaqueous slide deposit along the east-central portion of the lake. Late Holocene sediments are thinner or absent, particularly at the north end of the lake. The middle Holocene erosion surface may have been produced by a drop in lake level. Alternatively, it may represent a change in climate during the transition between the relatively warm Holocene hypsithermal and cool neoglacial. At this time (4600 ¹⁴C yr B.P.) circulation in Owasco Lake appears to have evolved from sluggish to active. The increased circulation, which persists today, probably resulted from atmospheric cold fronts with strong southwesterly winds that piled up water at the north end of the lake. The increased water circulation may have been ultimately driven by decreasing insolation, which produced an increased pole-to-equator thermal gradient and, thus, stronger global winds that began at the transition between the hypsithermal and neoglacial.  相似文献   

Induced stresses and fault potential in eastern Canada due to a realistic load: a preliminary analysis   总被引：1，自引：0，他引：1  

Patrick Wu  Henry S. Hasegawa 《Geophysical Journal International》1996,127(1):215-229

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基于小波统计特性的遥感图像像素与特征联合最优融合方法   总被引：8，自引：0，他引：8  

肖刚  敬忠良  HenryLeung  王淑 《遥感学报》2005,9(4):381-386

遥感影像的IHS融合方法由于匹配误差导致光谱畸变和退化,而小波变换在变换域具有良好的分频特性,小波系数的统计特性反映了遥感影像的边缘、线和区域等显著特征。提出了基于小波统计特性的遥感影像的像素和特征联合最优融合方法,在IHS空间,对强度分量I的高频部分利用多分辨率小波融合方法进行影像的高频细节特征融合,低频部分选取光谱信息和空间分辨率评价指标作为融合权系数求优指标,进行像素级最优融合,实验结果证明了该方法的有效性。  相似文献   

F-OH exchange equilibria between mica-amphibole mineral pairs     

Henry R. Westrich 《Contributions to Mineralogy and Petrology》1982,78(3):318-323

Fluoride-hydroxyl exchange equilibria between phlogopite-pargasite and phlogopite-tremolite mineral pairs were experimentally determined at 1,173K, 500 bars and 1,073–1,173 K, 500 bars respectively. The distribution of fluorine between phlogopite and pargasite was found to favor phlogopite slightly, G _ex ^. (1,173 K)=–1.71 kJ anion^–1, while in the case of phlogopite-tremolite, fluorine was preferentially incorporated in the mica, G _ex ^. (1,073)=– 5.67 kJ anion^–1 and G _ex ^. (1,173K)=–5.84 kJ anion^–1. These results have yielded new values of entropy and Gibbs energy of formation for fluortremolite, S _f =–2,293.4±16.0JK^–1 mol^–1 and G _f = –11,779.3±25.0 kJ mol^–1, respectively. In addition, F-OH mineral exchange equilibria support a recent molten oxide calorimetric value for the Gibbs energy of fluorphlogopite, G _f =–6,014.0±7.0 kJ mol^–1, which is approximately 40 kJ mol^–1 more exothermic than the tabulated value.This work performed in part at Sandia National Laboratories supported by the U.S. Department of Energy, DOE, under contract number DE-AC04-76DP00789  相似文献   

Iron metal production in silicate melts through the direct reduction of Fe(II) by Ti(III), Cr(II), and Eu(II)     

Henry D. Schreiber  G.Bryan Balazs  Andrew P. Shaffer  P.Lynne Jamison 《Geochimica et cosmochimica acta》1982,46(10):1891-1901

The production of metallic iron in silicate melts by the chemical reactions, 2Ti³⁺_(melt) + Fe²⁺_(melt) → 2Ti⁴⁺_(melt) + Fe⁰_(crystal)2Cr²⁺_(melt) + Fe²⁺_(melt) → 2Cr³⁺_(melt) + Fe⁰_(crystal)2Eu²⁺_(melt)+ Fe²⁺_(melt) → 2Eu³⁺_(melt) + Fe⁰_(crystal) has been demonstrated under experimental conditions in a simplified basaltic liquid, Such reactions may occur in lunar basalts and other reduced systems, and, thus, may aid in the understanding of the reduced nature of lunar basalts. The reactions were studied in a glass-forming Na-Ca-Mg-Al-silicate composition at a melt temperature of 1250°C and an imposed oxygen fugacity at the C/CO buffer (1 atm total pressure). Microtitrations of individually-doped samples were used in the quantitative assessment of their redox ratios and for the calibration of visible and near-infrared spectral absorptions. These spectral absorptions were then applied to the evaluation of the mutual redox interactions in dual-doped samples.  相似文献   

Climate response to astronomical forcing     

Claes G.H. Rooth  Cesare Emiliani  Henry W. Poor 《Earth and Planetary Science Letters》1978,41(4):387-394

Power spectrum analysis of the oxygen isotopic records of deep-sea cores cannot be directly used for correlation studies with the astronomical forcing functions because of the rapidity of the major deglaciations. The ensuing step change in the isotopic curves, repeated at somewhat irregular intervals, produces, in fact, substantial spectral energy in a wide frequency band that includes the frequencies of the precessional parameters.The isotopic fluctuations within the ramp sections of a composite core curve have been found to be highly correlated with the precessional parameters, indicating a linear response of climate to these parameters and verifying, at the same time, the essential correctness of the time scale adopted.A direct correlation of eccentricity with the major glacial/interglacial cycle is doubtful because some of the eccentricity minima have absolute values of the same order as some of the maxima, while the isotopic amplitude remains essentially constant. In order to test if the major cycle could be related to a terrestrial parameter exhibiting an asymmetric relaxation fluctuation, we have added an asymmetric saw-tooth function to an artificial curve constructed from the precessional parameters on the basis of optimal response amplitude. The curve thus generated reproduces the original isotopic curve with a similarity sufficient to warrant a close search and analysis of the relaxation process.  相似文献   

The early Cenozoic tectonic history of the southeast Pacific     

Henry Stommel 《Earth and Planetary Science Letters》1982,61(1):63-67

It is suggested that the hydrothermal vents of the South Pacific Rise produce a beta-governed circulation at mid-depth, and that perhaps the associated plume of excess³He (Lupton and Craig [1]) points westward because of the dynamics of this circulation rather than as a passive tracer.  相似文献   

An operational method for the real-time monitoring of E. coli numbers in bathing waters     

Lebaron P  Henry A  Lepeuple AS  Pena G  Servais P 《Marine pollution bulletin》2005,50(6):652-659

The aim of this study was to investigate the potential application of the beta-d-glucuronidase (GLUase) activity measurement for the routine detection and quantification of E. coli in marine bathing waters. GLUase activity was measured as the rate of hydrolysis of 4-methylumbelliferyl-beta-d-glucuronide. Culturable E. coli were quantified by the most probable number (MPN) microplate method. Both methods were applied to a large set of seawater samples. Significant correlation was found between the log of GLUase activity and the log of culturable E. coli. The mean coefficient of variation (CV) of the GLUase activity was less than 15% at concentrations around the current standards of International regulations whereas the CV of the microplate method was around 30%. When samples were stored at 4 degrees C and 20 degrees C, the mean CV of the GLUase activity remained below 15% up to 6 hours after sample collection whereas the range of variation of the microplate method varied between 10 and 50%. We concluded that the GLUase activity is an operational, reproducible, simple, very rapid and low cost method for the real-time enumeration of E. coli in bathing waters and should be preferred to the microplate method. The GLUase activity method should be routinely applied to the rapid enumeration of E. coli in recreational waters and recommendations for its application were suggested to water quality managers.  相似文献   

Magnesium self-diffusion in orthoenstatite     

Craig S. Schwandt  Randall T. Cygan  Henry R. Westrich 《Contributions to Mineralogy and Petrology》1998,130(3-4):390-396

Magnesium self-diffusion coefficients were determined experimentally for diffusion parallel to each of the three crystallographic directions in natural orthoenstatite (En₈₈Fs₁₂). Experiments were conducted at 1 atm in CO-CO₂ gas mixing furnaces, which provided oxygen fugacities equivalent to the iron-wüstite buffer. Diffusion of ²⁵Mg was induced in polished samples of oriented orthoenstatite using a film of isotopically enriched ²⁵MgO as the source material. Very short (<0.15 μm) diffusional penetration profiles were measured by ion microprobe depth profiling. The diffusion coefficients determined for four temperatures (900, 850, 800, 750 °C) provide the activation energies, E _a , and frequency factors, D _o, where D = D _o exp (−E _a /RT) for Mg self-diffusion parallel to each crystallographic direction: a-axis, E _a  = 360 ± 52 kJ/mole and D _o = 1.10 × 10⁻⁴ m²/s; b-axis, E _a  = 339 ± 77 kJ/mole and D _o = 6.93 × 10⁻⁶ m²/s and c-axis, E _a  = 265 ± 66 kJ/mole and D _o = 4.34 × 10⁻⁹ m²/s. In this temperature range, any possible anisotropy of cation diffusion is very small, however the activation energy for diffusion parallel to the c-axis (001) is the lowest and the activation energies for diffusion parallel to the a-axis (100) and b-axis (010) are higher. Application of these diffusion results to the silicate phases of the Lowicz mesosiderite meteorite provides cooling rates for the silicate portion of the meteorite (4–11 °C/100 years) that are similar, although slower, to previous estimates. These silicate cooling rates are still several orders of magnitude faster than the cooling rates (0.1 °C/10⁶ years) for the metal portions. Received: 22 January 1997 / Accepted: 2 October 1997  相似文献