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941.
南海神狐海域含水合物层底栖有孔虫群落结构与同位素组成 总被引:1,自引:0,他引:1
为评价水合物甲烷对底栖有孔虫群落结构和同位素的影响,对南海北部神狐海域获取天然气水合物的钻孔BY3岩心,进行底栖有孔虫群落结构和稳定同位素分析,发现含水合物层底栖有孔虫丰度、分异度下降,群落中以内生种占绝对优势,有孔虫破碎率增加;与不含水合物层中的底栖有孔虫相比,含水合物层的底栖有孔虫碳同位素值出现较明显的负偏移。含水合物层中的Uvigerinaspp.、Cibicidesspp.和Oridorsalisspp.的δ13C平均值分别为-1.61‰、-0.79‰和-1.80‰,而在不含水合物层它们的δ13C平均值分别为-0.88‰、-0.27‰和-1.04‰;其中Uvigerinaspp.和Oridorsalisspp.的δ13C最轻值均出现在含水合物层,分别为-1.83‰和-2.29‰。这些说明底栖有孔虫在生长和埋藏过程中可能受到沉积物中甲烷水合物形成和演化的影响。 相似文献
942.
943.
Wynn C. G. Ho † David L. Kaplan ‡ Philip Chang Matthew van Adelsberg Alexander Y. Potekhin 《Monthly notices of the Royal Astronomical Society》2007,375(3):821-830
RX J1856.5−3754 is one of the brightest nearby isolated neutron stars (INSs), and considerable observational resources have been devoted to it. However, current models are unable to satisfactorily explain the data. We show that our latest models of a thin, magnetic, partially ionized hydrogen atmosphere on top of a condensed surface can fit the entire spectrum, from X-rays to optical, of RX J1856.5−3754, within the uncertainties. In our simplest model, the best-fitting parameters are an interstellar column density N H ≈ 1 × 1020 cm−2 and an emitting area with R ∞ ≈ 17 km (assuming a distance to RX J1856.5−3754 of 140 pc), temperature T ∞ ≈ 4.3 × 105 K , gravitational redshift z g ∼ 0.22 , atmospheric hydrogen column y H ≈ 1 g cm−2 , and magnetic field B ≈ (3–4) × 1012 G ; the values for the temperature and magnetic field indicate an effective average over the surface. We also calculate a more realistic model, which accounts for magnetic field and temperature variations over the NS surface as well as general relativistic effects, to determine pulsations; we find that there exist viewing geometries that produce pulsations near the currently observed limits. The origin of the thin atmospheres required to fit the data is an important question, and we briefly discuss mechanisms for producing these atmospheres. Our model thus represents the most self-consistent picture to date for explaining all the observations of RX J1856.5−3754. 相似文献
944.
945.
基于J2EE的数据通用性操作框架的研究与实现 总被引:2,自引:0,他引:2
数据操作是基于J2EE的多级应用开发中常见而又具有通用性的重要一部分,而框架技术的研究可以实现软件开发过程中的重用,提高软件开发效率和质量。通过对国内外成熟的开发框架进行研究,并综合各自的优点形成一套在开发中可以保证数据操作模块具有可重用、可扩展、稳定性好等优势的方案;同时结合电子政务中的一个应用实例给出了数据通用性操作框架技术在企业级开发中的具体实现。 相似文献
946.
Experimental evidence has indicated that the critical state line determined from undrained compression tests is not identical to that determined from undrained extension tests. The purpose of this paper is to investigate a modelling method that accounts for the non‐uniqueness of critical state lines in the compression and the extension testing conditions. Conventional elastic–plastic cap models can predict only a unique critical state line for the compression and the extension tests. A new micromechanical stress–strain model is developed considering explicitly the location of critical state line. The model is then used to simulate undrained triaxial compression and extension tests performed on isotropically consolidated samples with different over‐consolidated ratios. The predictions are compared with experimental results as well as that predicted by models with kinematic hardening of yield surface. All simulations demonstrate that the proposed micromechanical approach is capable of modelling the undrained compression and the undrained extension tests. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
947.
948.
The two-dimensional wavelet transform is a very efficient bandpass filter, which can be used to separate various scales of processes and show their relative phase/location. In this paper, algorithms and techniques for automated detection and tracking of mesoscale features from satellite imagery employing wavelet analysis are developed. The wavelet transform has been applied to satellite images, such as those from synthetic aperture radar (SAR), advanced very-high-resolution radiometer (AVHRR), and coastal zone color scanner (CZCS) for feature extraction. The evolution of mesoscale features such as oil slicks, fronts, eddies, and ship wakes can be tracked by the wavelet analysis using satellite data from repeating paths. Several examples of the wavelet analysis applied to various satellite images demonstrate the feasibility of this technique for coastal monitoring 相似文献
949.
Young-Fo Chang Chien-Chih Chen Chieh-Yu Liang 《Geophysical Journal International》2007,170(1):170-174
The 1999 September 20 Chi-Chi earthquake is the largest seismic event which occurred in the island during the twentieth century. Available seismic data relative to this earthquake are of high quality, and surface ruptures identified as features associated to the Chelungpu fault can be clearly observed at the surface and precisely mapped. We calculated the fractal dimension ( D ) and b value of Gutenberg–Richter law for 6-month aftershocks of the Chi-Chi earthquake for the fault area, and find that the surface ruptures exhibit self-similar geometry only within specific ruler intervals. The D values of the surface ruptures reflect the fault slip and geometry at depth. More importantly, the small-size aftershocks seem more likely to occur within high D value and high b value areas, whereas small D value and small b value areas have a high potential for medium- and large-size aftershocks. 相似文献
950.
内蒙古新上海庙地区是煤田地质勘探的空白区,其地表为干旱、半干旱沙漠及黄土覆盖,属地震条件复杂地区。本次勘探在“三边”工作基础上,优化地震工程设计,共布设地震测线16条。经充分实验,确定了激发参数及接收参数。根据勘探区地震地质条件横向变化大的特点,在处理中始终以三高为中心,以静校正、反褶积为重点,选择最佳处理流程及参数,基本控制了区内主要可采煤层赋存情况,并否定了原断距1700m的区域大断层一沙葱沟断层。 相似文献