检索结果-南通市图书馆

Characteristics of energy dissipation in hyperconcentrated flows

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2008年第4期23卷 387-397页

作者： An-ping SHU 1,Qing-quan LIU2.Yu-jun YI 3,and Zhi-dong ZHANG 41 Assoc.Prof.,School of Environment,key laboratory of Water and Sediment Sciences of Ministry of Education,{2. {2. university,{2. 100875,china2.Prof.,Institute of Mechanics,Chinese Academy of Sciences,{2. 100080,china3 Lecturer,Dr.,School of Environment,{2. {2. university,{2. 100875,china4 Graduate student,School of Environment,{2. {2. university,{2. 100875,china [a]Assoc. Prof. School of Environment key laboratory of Water and Sediment Sciences of Ministry of Education beijing normal{2. beijing 100875 china [b]Prof. Institute of Mechanics Chinese Academy of Sciences beijing 100080 china [c]Lecturer Dr. School of Environment beijing normal{2. beijing 100875 china. The project is supported by the National Natural Science Foundation of china (Grant No. 10672.2.) [d]Graduate student School of Environment beijing normal{2. beijing 100875 china

An equilibrium equation for the turbulence energy in sediment-laden flows was derived on the basis of solid–liquid two-phase flow theory. The equation was simplified for two-dimensional, uniform, steady and fully developed turbulent hyperconcentrated flows. An energy efficiency coefficient of suspended-load motion was obtained from the turbulence energy equation, which is defined as the ratio of the sediment suspension energy to the turbulence energy of the sediment-laden flows. laboratory experiments were conducted to investigate the characteristics of energy dissipation in hyperconcentrated flows. A total of 115 experimental runs were carried out, comprising 70 runs with natural sediments and 45 runs with cinder powder. Effects of sediment concentration on sediment suspension energy and flow resistance were analyzed and the relation between the energy efficiency coefficient of suspended-load motion and sediment concentration was established on the basis of experimental data. Furthermore, the characteristics of energy dissipation in hyperconcentrated flows were identified and described. It was found that the high sediment concentration does not increase the energy dissipation; on the contrary, it decreases flow resistance.

关键词： Hyperconcentrated flows Turbulence energy Efficiency coefficient Energy dissipation

An eSnake model for medical image segmentation

在线全文

同方期刊数据库

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. of Medical Physics and Engineering, beijing 100871, china 2. key {2. of Pure and Applied Mathematics, School of Mathematical Sciences, Peking university, beijing 100871, china) The Research Center for Tumor Diagnosis and Therapeutical Physics & beijing key {2. of Medical Physics and Engineering Beijing 100871 China key laboratory of Pure and Applied Mathematics School of Mathematical Sciences Peking University 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.

Holocene climate variation denoted by Barkol Lake sediments in northeastern Xinjiang and its possible linkage to the high and low latitude climates

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 2011年第4期54卷 603-614页

作者： XUE JiBin & ZHONG Wei 1 School of geography,South china{2. university,Guangzhou 510631,china 2.key laboratory of Oasis Ecology(Ministry of Education) ,Xinjiang university,Urumqi 830046,china 3 key laboratory of Western china's Environmental Systems(Ministry of Education) ,Lanzhou university,Lanzhou 730000,china 1. School of geography South China Normal University Guangzhou 510631 China2. Key Laboratory of Oasis Ecology (Ministry of Education) Xinjiang University Urumqi 830046 China3. Key Laboratory of Western China’s Environmental Systems (Ministry of Education) Lanzhou University Lanzhou 730000 China

The climate over the closed inland Barkol Lake,which is located in northeastern Xinjiang Uygur Autonomous Region,is significantly influenced by westerly winds *** improve our understanding of past climate processes in westerly wind influenced regions in northwestern china,a 2.0-cm sediment section was retrieved from this *** taking the carbon reservoir effect into consideration,the chronological sequence of this section was reconstructed based on seven conventional radiocarbon dates of bulk samples,and the bottom age of this section was determined to be about 9400 cal a ***-proxy datasets,includingδ18O car,δ13C car of authigenic carbonate,and total organic carbon were examined using wavelet analysis and singular spectrum analysis *** show that the Holocene in the Barkol Lake region can be divided into four stages:(1) a cold and dry early stage before～8000 cal a BP;(2. a moderately warm and wet middle stage between～8000 and 6000 cal a BP;(3) a warm and dry stage,along with a cooling-wetting tendency from 6000 to 2.00 cal a BP;and(4) a fluctuating cooling and wet stage between 2.00-800 cal a BP,and a drier stage since 800 cal a *** general trend of Holocene climatic changes revealed by Barkol Lake sediments was in agreement with that of adjacent *** infer that climatic changes during the Holocene in the Barkol Lake region were influenced not only by high latitudes,especially the North Atlantic region climate,but also tropical low-latitude processes,such as the El Nio/La Nia-Southern *** study demonstrates that the enhanced activities of ENSO may have played an important role in climatic changes in northeastern Xinjiang during the *** results also suggest that climatic patterns may be temporally different in the northern Xinjiang area in response to the changing predominant control of either the Westerly or the Asian summer monsoon,depending on the contrast of their relative strengths.

关键词： Barkol Lake Holocene climate change tropical processes northern high-latitude climate

Wave coupling between the Tianshan orogen and the deformations in its south and north foreland basins in Cenozoic

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 61-69页

作者： CHEN ShuPing1,2.TANG LiangJie & YU YiXin1,2.1 State key laboratory of Petroleum Resource and Prospecting,{2. {2. of Petroleum,beijing 102.49,{2. 2.Department of Geoscience,{2. {2. of Petroleum,beijing 102.49,{2. china Univ Petr State Key Lab Petr Resource & Prospecting Beijing 102249 Peoples R China china Univ Petr Dept Geosci Beijing 102249 Peoples R China

Attention has been paid to the deformations in the south and north foreland basins of the Tianshan Mountains and their relations to the tectonic movements of the mountains. Based on the seismic data interpretation and field work,the tectonic features,tectonic styles,controlling factors of deformation,deformation time,and their relationships in the three tectonic units were comparably studied. The Ce-nozoic deformations in the two foreland basins were characterized by zonation from south to north,segmentation from west to east,and layering from deep to shallow. The tectonic styles are compres-sive ones,including both basement-involved and cover-detaching. The two foreland basins underwent several times of deformation in Cenozoic and the deformations were transmitted from the Tianshan orogen to the inner basin. The deformation dynamics of the south and north foreland basins of the Tianshan Mountains can be represented by dynamics of orogenic wedges. In terms of the deformations of the wedges with wave-like features,the concept of a wave orogenic wedge was put forward,and a double wave orogenic wedge model was established.

关键词： Tianshan orogen basin-mountain coupling tectonics wave orogenic wedge

Study on Green Residential Space Design

在线全文

学校读者我要写书评

暂无评论

IJLAI Transactions on Science and Engineering

IJLAI Transactions on Science and Engineering 2024年第1期2卷 32-37页

作者： Yu Jiang Shenyang normal university No.2.3 Huanghe North Street Shenyang 110034China

With the ever-changing nature,green ecology has become an international trend of ***,the green ecological design of residential space has become the main melody of people’s *** always implement the concept of ecological and environmental protection in the design process,attach importance to the ecological effect of residential space,carry out reasonable budget and use of environmentally friendly decorative materials,reduce the waste of materials,save money and save resources at the same time,and protect the *** the same time,people began to put their hopes on the residential space design,which made the green residential space design began to *** the bold exploration and practice of designers,the design of green residential space will be endowed with more distinctive characteristics and unique *** from the concept of green design,this paper explores the method of green space design through typical analysis.

关键词： Green Residential space Haze

Propagation characteristics of converted refracted wave and its application in static correction of converted wave

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science china Earth Sciences 2008年第S2期51卷 226-232页

作者： LIU Yang1,2.& WEI XiuCheng3 1 State key laboratory of Petroleum Resource and Prospecting,{2. {2. of Petroleum,beijing 102.49,{2. 2.CNPC Geophysical Exploration key laboratory,{2. {2. of Petroleum,beijing 102.49,{2. 3 Exploration and Production Research Institute,SINOPEC,beijing 100083,{2. china Univ Petr State Key Lab Petr Resource & Prospecting Beijing 102249 Peoples R China china Univ Petr CNPC Geophys Explorat Key Lab Beijing 102249 Peoples R China SINOPEC Explorat & Prod Res Inst Beijing 100083 Peoples R China

Three-component seismic exploration through P-wave source and three-component geophone is an effective technique used in complicated reservoir exploration. In three-component seismic exploration data processing,one of the difficulties is static correction of converted wave. This paper analyzes propagation characteristics of non-converted and converted refracted waves,and discovers a favor-able condition for the formation of converted refracted wave,i.e. the velocity of overlaying medium S wave is much lower than that of underlying medium S wave. In addition,the paper proposes the static correction method of converted wave based on PPS converted refracted wave,and processes the real three-component seismic data with better results of static correction of converted wave.

关键词： PPS converted refracted wave converted wave static correction

Recovery of functions via their irregular sampling values

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1998年第4期43卷 268-271页

作者： FANG Gensun Department of Mathematics, beijing normal university, beijing{2., china Department of Mathematics Lkijing Normal University Beijing China

It is proved that if a function can be completely reconstructed by tempered splines which satisfy the real Kiesz basis condition as the degree of spline goes to infinity, then the function is band limited.

关键词： band limited function cardinal splines irregular sampling.

在线全文

学校读者我要写书评

暂无评论

Saturated models

Chinese Science Bulletin 1998年第7期43卷 562-564页

作者： CHEN Guolong Department of Mathematics, beijing normal university, beijing{2., china Department of Mathematics Beijing Normal University Beijing China

An equivalent description of saturated models is given, and some properties of countable saturated models, almost saturated models and full models are discussed. New proofs of two important theorems of the related doc... 详细信息

关键词： almost saturated model full model power type.

Level Set interface treatment and its application in Euler method

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2010年第2期53卷 227-236页

作者： WU KaiTeng1,2.HAO Li3,WANG Cheng4 & ZHANG Li1,2.1 Numerical Simulation Sichuan Higher School key laboratory,Neijiang {2. {2.,Neijiang 641112.china 2.College of Mathematics and Information Science,Neijiang {2. {2.,Neijiang 641112.china 3 College of Science,beijing {2. of Civil Engineering and Architecture,beijing 100044,china 4 State key laboratory of Explosion Science and Technology,beijing Institute of Technology,beijing 100081,china 1. Numerical Simulation Sichuan Higher School key laboratory Neijiang Normal University Neijiang 641112 China2. College of Mathematics and Information Science Neijiang Normal University Neijiang 641112 China3. College of Science Beijing University of Civil Engineering and Architecture Beijing 100044 China4. State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology Beijing 100081 China

Level Set interface treatment method is introduced into Euler method,which is employed for interface treatment method for multi-materials. Combined with the ghost fluid method,the moving interface is tracked. Fifth-order WENO spatial discretization and third-order TVD Runge-Kutta time discretization methods are used. Shock-wave action on bubble,implosion and velocity field Shock effect bubbles; implosion and velocity field are simulated by means of LS-MMIC3D programmed by C++. Nu-merical results show that the Level Set interface treatment method is effective and feasible for multi-material interface treatment in comparison with the WENO method.

关键词： Euler method Level Set method shock-wave action on bubble implosion numerical simulation