检索结果-南通市图书馆

The attenuation anisotropy of mudstones and shales in subsurface formations

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2005年第11期48卷 1882-1890页

作者： SHI Ge1 & DENG Jixin1,2.1. The Key labratory of Orogenic Belts and Crustal Evolution, School of Earth and Space sciences, Peking {2., beijing 100871, china 2. Geophysical Prospecting Key lab (CNPC), {2. of Petroleum, beijing 102.49, china The Key labratory of Orogenic Belts and Crustal Evolution School of Earth and Space Sciences Peking University Beijing China Geophysical Prospecting Key lab (CNPC) University of Petroleum Beijing China

We have measured the relationships in the laboratorial condition between the at-tenuation in three samples of mudstones and shales as well as two samples of layered sand-stones and the alteration in direction, confining pressure and pore fluid. The relative contributions of different attenuation mechanisms are also discussed. Studies show that the attenuation in dry and saturated samples is strongly related to pressure and direction. The attenuation coefficient of P-wave propagating parallel to bedding (PH ) is less than that of P-wave propagating vertical to bedding (PV ), while the attenuation coefficient of S-wave both propagating and vibrating parallel to bedding (SH ) and that of S-wave propagating vertical to bedding while vibrating parallel to bedding (SV1) are less than that of S-wave propagating parallel to bedding while vibrating verti-cal to bedding (SV ). Under oil saturated conditions, the Biot flow attenuation acts as the domi-nant mechanism for waves propagating parallel to bedding, while the frame anelastic attenuation and squirt flow attenuation seem to play important roles in condition of propagation vertical to bedding.

关键词： mudstone, shale, attenuation, anisotropy, attenuation mechanism

A new transient stability margin based on dynamic security region and its applications

在线全文

学校读者我要写书评

暂无评论

Science china(Technological {2.) 2008年第6期51卷 751-760页

作者： XUE AnCheng1, 2.& MEI ShengWei1 1 State Key lab of Power Systems, Department of Electrical Engineering, Tsinghua university, {2. 100084, china 2.Key lab of Systems and Control, Institute of Systems Science, Chinese Academy of sciences, {2. 100190, china State Key lab of Power Systems Department of Electrical Engineering Tsinghua University Beijing China Key lab of Systems and Control Institute of Systems Science Chinese Academy of Sciences Beijing China

A new transient stability margin is proposed based on a new expression of dynamic security region (DSR) which is developed from the existing expression of DSR. Applications of the DSR based transient stability margin to contingency ranking and screening are discussed. Simulations in the 10-machine 39-bus New England system are performed to show the effectiveness of the proposed DSR based tran-sient stability margin.

关键词： dynamic security region (DSR) transient stability margin contingency screening

An eSnake model for medical image segmentation

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2005年第5期15卷 424-429页

作者： Lv Hongyu1, YUAN Kehong2. BAO Shanglian1, ZU Donglin1 and DUAN Chaijie1*(1. The Research center for Tumor Diagnosis and Therapeutical Physics & beijing Key {2.oratory of Medical Physics and Engineering, beijing 100871, china 2. Key {2.oratory of Pure and Applied Mathematics, School of Mathematical sciences, Peking university, beijing 100871, china) beijing Key lab. of Med. Phys. and Eng. Res. Ctr. for Tumor Diagnosis and Therapeutical Phys. Beijing 100871 China Key lab. of Pure and Applied Math. Sch. of Math. Sci. Peking Univ. Beijing 100871 China

A novel scheme of external force for detecting the object boundary of medical image based on Snakes (active contours) is introduced in the paper. In our new method, an electrostatic field on a template plane above the original image plane is designed to form the map of the external force. Compared with the method of Gradient Vector Flow (GVF), our approach has clear physical meanings. It has stronger ability to conform to boundary concavities, is simple to implement, and reliable for shape segmenting. Additionally, our method has larger capture range for the external force and is useful for medical image preprocessing in various applications. Finally, by adding the balloon force to the electrostatic field model, our Snake is able to represent long tube-like shapes or shapes with significant protrusions or bifurcations, and it has the specialty to prevent Snake leaking from large gaps on image edge by using a two-stage segmentation technique introduced in this paper. The test of our models proves that our methods are robust, precise in medical image segmentation.

关键词： image segmentation eSnake external force electrostatic field balloon force.

Petrogenesis of Songshugou dunite body in the Qinling orogenic belt, Central china: Constraints from geochemistry and melt inclusions

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china Earth sciences 2005年第8期48卷 1146-1157页

作者： SU Li1,2. SONG Shuguang3 & ZHOU Dingwu1 1. Key laboratory of Continental Dynamics of the Ministry of Education, Department of Geology, Northwestern university, Xi’an 710069, {2. 2. The Geological lab center, {2. university of Geosciences (beijing), beijing 100083, {2. 3. Key laboratory of Orogenic Belts of the Ministry of Education, Department of Geology, Peking university, beijing 100871, {2. Key laboratory of Continental Dynamics of the Ministry of Education Department of Geology Northwestern University Xi’an China The Geological lab {2. China University of Geosciences (Beijing)Beijing China Key laboratory of Orogenic Belts of the Ministry of Education Department of Geology Peking University Beijing China

The Songshugou dunite body, which occupies an area of about 2. km2. is the largest ultramafic massif in the eastern Qinling orogenic belt, Central china. The major compo-nent of this body is dunitic rocks including mylonitic dunite and coarse-grained dunite; they oc-cupy about 95 vol% of the total body. Petrography, mineral composition, major and trace ele-ments and primitive melt inclusions have been investigated in this paper; all revealed that this dunite body is the product of melt-rock interaction by porous percolation flow. In comparison with dunite sills or veins in harzburgite from the basal part of Oman ophiolite, this dunite body is characterized by lower contents of Al2.3, CaO and HREE but higher content of highly incom-patible elements and Zr and Hf. The LREE enriched patterns and primitive mantle normalized spidergrams of trace elements are also different from the Oman dunite. Combining with melt in-clusions observed in olivines, we conclude that this dunite body is the product of large- scale porous percolation flow of high-MgO melts within depleted mantle peridotites. The high-MgO magma, in essence, was most probably produced at the hot head of an upwelling mantle plume. The occurrence of the Songshugou dunite body is closely associated with the activity of mantle super-plume in Neo-Proterozoic era in the Yangtze Craton.

关键词： Songshugou dunite body, geochemistry, melt inclusion, mantle plume, Qinling orogenic belt.

Differential retardation of organic matter maturation by overpressure

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2004年第9期47卷 783-793页

作者： HAO Fang1,2. JIANG Jianqun1, ZOU Huayao1, FANG Yong1 & ZENG Zhiping2.1. Key lab for Hydrocarbon Accumulation Mechanism in the Ministry of Education, Petroleum university, {2. 102.49, china 2. Department of Petroleum Geology, china university of Geosciences, Wuhan 430074, china Key lab for Hydrocarbon Accumulation Mechanism in the Ministry of Education Petroleum University Beijing China Department of Petroleum Geology China University of Geosciences Wuhan China

The thermal evolution of organic matter (OM) is composed of a series of reactions that are paralell and successive with each other. Different reactions have different activation energy, different rates of product concentration variation, and different volume expansion effects, and therefore have different responses to overpressure, which determines the differential retardation of different OM maturation reactions and maturity parameters. Based upon comprehensive studies on the OM maturation in different pressure systems in the Yinggehai, Qiongdongnan and Bohai Bay basins, 4 hierarchies of overpressure retardation have been recognized. (1) OM maturation in all aspects has been retarded by overpressure. (2. The thermal evolution of hydrocarbons and thermal degradation of hydrogen-rich kerogens has been retarded, but the thermal evolution of hydrogen-poor kerogen components has not been affected by overpressure. As a result, vitrinite reflectance has not been retarded. (3) The thermal cracking of hydrocarbons has been retarded, yet overpressure has had little or no effect on thermal degradation of kerogens. (4) Overpressure has no detectable effect on all aspects of OM maturation. The hierarchy that overpressure has retarded all aspects of OM maturation is the combined result of early overpressure (overpressure began to develop when the source rock was still immature) and the protracted maintenances of closed fluid system. Any case that overpressure had developed too late, or overpressure was too small to reach the threshold values, or overpressured fluid had been frequently released, could give rise to the occurrence of state 4 that overpressure had no detectable effect on all aspects of OM maturation. It seems that in many basins, overpressure retardation of hierarchies 2.and 3 developed where the most commonly used maturity parameter, vitrinite reflectance, had not been affected. In theses cases, multiple parameters must be used to distinguish overpressure retardati

关键词： overpressure, organic matter maturation, hydrocarbon generation, differential retardation.

Status of study on biological and toxicological effects of nanoscale materials

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2005年第5期48卷 385-394页

作者： WANG Bing1, FENG Weiyue1, ZHAO Yuliang1, XING Gengmei1, CHAI Zhifang1, WANG Haifang2.& JIA Guang3 1. laboratory for Bio-Environmental Health sciences of Nanoscale Materials (Nanosafety lab), Institute of High Energy Physics, Chi-nese Academy of sciences, beijing 100049, china 2. College of Chemistry and Molecular Engineering, Peking university, beijing 100871, china 3. Department of Occupational and Environmental Health sciences, School of Public Health, Peking university, beijing 100083, china laboratory for Bio-Environmental Health sciences of Nanoscale Materials (Nanosafety lab) Institute of High Energy Physics Chinese Academy of Sciences Beijing China College of Chemistry and Molecular Engineering Peking University Beijing China Department of Occupational and Environmental Health sciences School of Public Health Peking University Beijing China

Because the physical and chemical properties of nanosized materials mostly differ from the existing microsized materials, their potential impacts on human health and the envi-ronment will be topics under the serious discussions in press and in a number of international scientific journals. We analyze and summarize the existing data of the experimental study on the biological activities and adverse effects of nanoscale materials/particles including single wall carbon nanotubes, multi wall carbon nanotubes, titanium oxide and iron powders. Though some biological behaviors of nanoscale materials observed cannot be understood on the basis of the current knowledge, as the existing data are mostly preliminary, it is too early to make some ex-clusive conclusions on biological activities (or the toxicity) of any of nanoscale materials. The experimental techniques, the current topics, and the future research directions for this new re-search field are also discussed.

关键词： nanomaterials, single wall carbon nanotubes, multi wall carbon nanotubes, titanium oxide and iron, biological activity and toxicological effect.

A 12.bit multichannel ADC for pixel detectors in particle physics and nuclear imaging

在线全文

学校读者我要写书评

暂无评论

Science china(Technological {2.) 2010年第5期53卷 1208-1214页

作者： WEI Wei1,2.3,WANG Zheng1,3 & ZHAO JingWei1,3 1 Institute of High Energy Physics,Chinese Academy of sciences,beijing 100049,{2. 2.Graduate university of Chinese Academy of sciences,beijing 100049,{2. 3 Key lab of Nuclear Detection Technology and Nuclear Electronics of Chinese Academy of sciences,beijing 100049,{2. Institute of High Energy Physics Chinese Academy of Sciences Beijing China Graduate university of Chinese Academy of sciences Beijing China Key lab of Nuclear Detection Technology and Nuclear Electronics of Chinese Academy of sciences Beijing China

Modern pixel detectors in nuclear and particle physics experiments and also in nuclear imaging,starve for highly integrated application specified integrated circuit(ASIC),whereas in china the study of ASIC still stays far away from practical *** lack of ASIC strictly limits the research and development of domestic high energy physics field.A 12.bit multichannel ADC designed for high density readout is introduced as a major candidate for solution.A precise model is discussed and the simulation fully agrees with the model,which indicates a key principle of *** is performed according to the given rule,and novel layout techniques are carried *** results in all aspects are also obtained,showing an excellent real performance,which satisfies the practical requirement.

关键词： application specified integrated circuit high density readout Wilkinson ADC multi-channel ADC

The correspondence between the concepts in description logics for contexts and formal concept analysis

在线全文

学校读者我要写书评

暂无评论

Science china(Information sciences) 2012年第5期55卷 1106-1122页

作者： MA Yue 1,2.SUI YueFei 1 & CAO CunGen 1 1 Key laboratory of Intelligent Information Processing,Institute of Computing Technology,Chinese Academy of sciences,{2. 100190,china 2.Graduate university of Chinese Academy of sciences,{2.,china Key laboratory of Intelligent Information Processing Institute of Computing Technology Chinese Academy of Sciences Beijing China Graduate university of Chinese Academy of sciences Beijing China

Formal concept analysis (FCA) and description logic (DL) are meant to be formalizations of concepts.A formal concept in the former consists of its intent and extent,where the intent is the set of all the attributes shared by each object in the extent of the concept,and the extent is the set of all the objects sharing each property in the intent of the concept.A concept in the latter formalization is simply a concept name,the interpretation of which is a subset of a *** consider the correspondence between concepts in both formalizations,a multi-valued formal context must be represented both as a knowledge base and as a model of the DL for contexts,where concepts are decomposed into tuple concepts C,interpreted as a set of tuples and value concepts V,interpreted as a set of attribute-value *** show that there is a difference between the interpretation of concepts R.V /R.C and the Galois connection between the extent/intent of formal concepts in *** to the Galois connection,there should be concepts of the form + R.V and + R.C inter-preted in FCA,and hence the logical language L for DL is extended to be L + together with + as a constructor so that + R.V and + R.C are well-defined ***,according to the interpretation in DL there should be pseudo concepts in FCA so that the interpretation of concepts R.V /R.C is the extent/intent of pseudo *** correspondence between formal concepts and concepts in L +,and between pseudo concepts and concepts in L are presented in this paper.

关键词： description logic formal concept analysis concept attribute/role

Study on attribute characterization for reservoir dynamic monitoring by seismic

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china Earth sciences 2008年第S2期51卷 218-225页

作者： CHEN XiaoHong1,3,LI JingYe2.3 & ZHAO Wei4 1 Key lab of Geophysical Exploration of CNPC,china Petroleum {2.,beijing 102.49,china 2.Basin & Reservoir Research center,china Petroleum {2.,beijing 102.49,china 3 State Key laboratory of Petroleum Resource and Prospecting,china {2. of Petroleum,beijing 102.49,china 4 Research center of CNOOC,beijing 10002.,china Key lab of Geophysical Exploration of CNPC China Petroleum University Beijing China State Key laboratory of Petroleum Resource and Prospecting China University of Petroleum Beijing China Basin & Reservoir Research center China Petroleum University Beijing China Research center of CNOOC Beijing China

Study on characterizing reservoir parameters dynamic variations by time-lapse seismic attributes is the theoretical basis for effectively distinguishing reservoir parameters variations and conducting time-lapse seismic interpretation,and it is also a key step for time-lapse seismic application in real oil fields. Based on the rock physical model of unconsolidated sandstone,the different effects of oil saturation and effective pressure variations on seismic P-wave and S-wave velocities are calculated and analyzed. Using numerical simulation on decoupled wave equations,the responses of seismic amplitude with different offsets to reservoir oil saturation variations are analyzed,pre-stack time-lapse seismic attributes differences for oil saturation and effective pressure variations of P-P wave and P-S converted wave are calculated,and time-lapse seismic AVO (Amplitude Versus Offset) response rules of P-P wave and P-S converted wave to effective pressure and oil saturation variations are compared. The theoretical modeling study shows that it is feasible to distinguish different reservoir parameters dynamic variations by pre-stack time-lapse seismic information,including pre-stack time-lapse seismic attributes and AVO information,which has great potential in improving time-lapse seismic interpreta-tion precision. It also shows that the time-lapse seismic response mechanism study on objective oil fields is especially important in establishing effective time-lapse seismic data process and interpreta-tion scheme.

关键词： time-lapse seismic dynamic monitoring rock physical model pre-stack attribute Amplitude Versus Offset (AVO)