NLS EQUATION OF INTERNAL WAVES IN WEAKLY STRATIFIED OCEAN   总被引：1，自引：0，他引：1  

徐肇廷  楼顺里  田纪伟 《中国海洋湖沼学报》1996,14(2):121-127

The NLS (Non-Linear Schr(?)dinger) equation of internal waves in a wekly stratified ocean is der-ived in phase coordnates in terms of the RPM (Reductive Perturbation Method). It was shown thatwhen AB>0 there exist modulation forms of envelope soliton and dn, and tha when AB<0 there arethree modulation forms dark soliton, sn and cn. Only if K~2>B/A(?) . the side-band perturbation is stable,otherwise unstable. For the stable side-band perturbation there ekisis a modulation form of MdV soliton.  相似文献   

The observation and simulation of diurnal surface thermal contrast in an Alaskan alpine pass     

Prof. Dr. Anthony Brazel  Dr. Samuel I. Outcalt 《Theoretical and Applied Climatology》1973,21(2-3):157-174

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超速电脑X光扫描机     

吴中辉 《CT理论与应用研究》1993,(1)

香港山顶地区的明德医院于1990年12月开始使用超速电脑CT 扫描机。这是除美国和日本外在亚太地区首家唯一装备有此种扫描机的医院。Imatron 超速CT 扫描机是目前使用电子射束技术的最先进的诊断成像系统。超速CT 扫描机完全放弃了传统的机械旋转探测器或X 射线管组合,既克服了广泛使用的常规CT 扫描机在扫描速度上的难关,又解决了X 射线管的热散失问题。  相似文献   

Assessment of Ground-Water Flow and Chemical Transport in a Tidally Influenced Aquifer Using Geostatistical Filtering and Hydrocarbon Fingerprinting   总被引：1，自引：0，他引：1  

Samuel A. Marquis  Jr.  Eric A. Smith 《Ground water》1994,32(2):190-199

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Isotopic composition of cellulose from aquatic organisms     

Michael J. DeNiro  Samuel Epstein 《Geochimica et cosmochimica acta》1981,45(10):1885-1894

The stable isotopic ratios of oxygen, carbon and the non-exchangeable carbon-bound hydrogen of cellulose from marine plants (algae and higher vascular forms) and animals (tunicates) collected in their natural habitats and from freshwater vascular plants grown in the laboratory under controlled conditions were determined.The δ¹⁸Ovalues of cellulose from all the plants and animals were 27 ±3% more positive than the δ¹⁸O values of the waters in which the organisms grew. Temperature had little or no influence on this relationship for three species of freshwater vascular plants that were analyzed. The relationship between the δ¹⁸O values of cellulose and the water used in its synthesis is probably established by the isotopic fractionation that occurs during the hydration of carbonyl groups of the intermediates involved in cellulose synthesis.The δD values of the non-exchangeable hydrogen of cellulose (determined by analyzing cellulose nitrate) from different organisms that grew in the same environment differed by large amounts. This difference ranged up to 200‰ for different species of algae collected at a single site: the corresponding difference for different species of tunicates and vascular plants was 60 and 20‰ respectively. The δD values of cellulose nitrate from different species of freshwater vascular plants grown in water of constant temperature and isotopic composition differed by as much as 60‰ The relationship between the δD values of the carbon-bound hydrogen of cellulose and the water used in its synthesis displayed a significant temperature dependence for four species of freshwater vascular plants that were analyzed. The δD values of cellulose nitrate prepared from different parts of one of the plants grown under constant conditions differed by 40‰ Hydrogen isotopic fractionation during cellulose synthesis appears to be more variable among different species and displays a larger temperature dependence than was suggested by previous studies.  相似文献   

Hydrogen and carbon isotopes of petroleum and related organic matter     

Hsueh-Wen Yeh  Samuel Epstein 《Geochimica et cosmochimica acta》1981,45(5):753-762

$\text{D}\text{H}$ and ${}^{13}\text{C}{}^{12}\text{C}$ ratios were measured for 114 petroleum samples and for several samples of related organic matter. δD of crude oil ranges from ?85 to ?181‰, except for one distillate (?250‰) from the Kenai gas field; δ¹³C of crude oil ranges from ?23.3 to ?32.5‰, Variation in δD and δ¹³C values of compound-grouped fractions of a crude oil is small, 3 and 1.1%., respectively, and the difference in δD and δ¹³C between oil and coeval wax is slight. Gas fractions are 53–70 and 22.6–23.2‰ depleted in D and ¹³C, respectively, relative to the coexisting oil fractions.The δD and δ¹³C values of the crude oils appear to be largely determined by the isotopic compositions of their organic precursors. The contribution of terrestrial organic debris to the organic precursors of most marine crude oils may be significant.  相似文献   

Evaluating System for Ground-Water Contamination Hazards Due to Gas-Well Drilling on the Glaciated Appalachian Plateau     

Samuel S. Harrison 《Ground water》1983,21(6):689-700

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Geotechnical properties of an attapulgite clay shale in northwestern nigeria     

Samuel Akinlabi Ola 《Engineering Geology》1982,19(1):1-13

The paper gives a brief review of the geology of the Iullemmeden Basin of northwestern Nigeria and how the stratigraphic sequence produces complex geotechnical problems. Mineralogical analysis showed the clay shale to be predominantly attapulgite. Detailed geotechnical properties of the clay showed the liquid limit to be greater than 200% and it depended significantly on treatment before testing. Very low maximum dry densities of 1137 kg/m³ (71 pcf), a high optimum moisture content of 41%, and a high compression index of 0.23 were obtained. The results presented also indicated that the attapulgite has very critical potential volume change. Results of the shear strength characteristics showed the effective cohesion to be zero in all the tests and a loss of strength of about 50% occurred as a result of decrease in the rate of strain.  相似文献   

A reexamination of cellulose carbon-bound hydrogen δD measurements and some factors affecting plant-water D/H relationships     

Crayton J Yapp  Samuel Epstein 《Geochimica et cosmochimica acta》1982,46(6):955-965

The method of Epstein et al. (1976) for analysis of D/H ratios of cellulose carbon-bound hydrogen has been modified. This modified “renitration” method yields δD values which are in agreement with those obtained by the sodium chlorite delignification method. Comparison of results obtained by the renitration method with the published results of Epstein et al. (1976) indicate some differences in the δD values of individual samples. However, the overall plant-water δD relationship determined by Epstein et al., is not greatly changed upon redetermination by the renitration method. Additional data from a variety of plants representing a wide geographical range reveal that relative humidity is an important variable in determining the δD value of cellulose C-H hydrogen on this inter-regional scale. The role of relative humidity can be reasonably explained by a leaf water model that assumes an isotopic steady-state during transpiration. These results reaffirm the conclusion of Epstein et al., that the δD variations of the source water are the dominant control of the δD variations of cellulose C-H hydrogen from naturally grown plants. Thus, there is an expectation that these cellulose δD variations can have climate significance.  相似文献   

Introduction of Gerald J. Wasserburg for the V. M. Goldschmidt Medal 1978     

Samuel Epstein 《Geochimica et cosmochimica acta》1979,43(3):439-440

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