检索结果-南通市图书馆

Adjoint method for the optimum planning of industrial pollutant sources

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2005年第8期48卷 1270-1279页

作者： LIU Feng1,2, HU Fei2 & ZHU Jiang2 1. College of Environmental Sciences, peking university, beijing 100871, China 2. LAPC, institute of Atmospheric Physics, Chinese Academy of Sciences,{3. 100029, China 1. College of Environmental Sciences Peking University 100871 Beijing China 2. LAPC Institute of Atmospheric Physics Chinese Academy of Sciences 100029 Beijing China

The optimum planning of industrial pollutant sources, which optimizes the economic object without violating environmental constraints, is an important and hard task to be conquered. In this paper, an adjoint method is developed to solve the problem. The penalty function is in-troduced to deal with the environmental inequality constraints, and Lagrange function is con-structed to derive the adjoint equation and the gradient of the object function. In this means, the gradient of the object function can be calculated by solving the adjoint equation, and the infor-mation from the gradient is used to make the object function descend and approach to an optimal solution after some iterations. A two-dimensional, simplified model is used for numerical experi-ments. The theoretical derivations are verified by the results of the experiments. Furthermore, the adjoint method is shown to be of excellent convergence and efficiency, which is adaptive to the fast development of air quality numerical models and super computers.

关键词： optimum planning, industrial pollutant sources, adjoint equation, penalty function, gradient.

Simulating the impacts of climate variation and land-cover changes on basin hydrology: A case study of the Suomo basin

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2005年第9期48卷 1501-1509页

作者： CHEN Junfeng1,2, LI Xiubin2 & ZHANG Ming2 1. institute of Remote Sensing & GIS, peking university, beijing 100871, China 2. institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, beijing 100101, China 1. institute of Remote Sensing & GIS Peking University 100871 Beijing China 2. institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences 100101 Beijing Chin

Impacts of land cover changes on watershed hydrology have been a long-term academic concern with acute dispute. But little attention has been paid to such effects on mesoscale river basins, where the society has a closer link to river hydrology. The present study focuses on a mesoscale river basin, the Suomo Basin that is located on the upper reaches of the Yangtze River. Land covers in the basin in the years 1970, 1986 and 1999 were mapped. A lumped hydrologic model, CHARM, and a distributed hydrologic model, SWAT, were used to model the impacts of both land-cover change and climate variation on river runoff during the past four decades. The results show that the contribution of climate variation to the change of runoff regime makes up 60%―80%, while that of land cover changes only 20%.

关键词： climate variation, land-cover changes, Suomo Basin, CHARM model, SWAT model.

Applications of functionalized ionic liquids

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2006年第5期49卷 385-401页

作者： LI Xuehui1, ZHAO Dongbin2,3. FEI Zhaofu2 & WANG Lefu1 1. Department of Chemical Engineering, Guangdong Provincial Laboratory of Green Chemical Technology, South China Uni-versity of Technology, Guangzhou 510641, China 2. Swiss Federal institute of Technology, Lausanne, EPFL, CH-1015 Lausanne, Switzerland 3. PKU Green Chemistry Center, beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, peking university,{3., China 1. Department of Chemical Engineering Guangdong Provincial Laboratory of Green Chemical Technology South China University of Technology Guangzhou 510641 China 2. Lausanne EPFL Swiss Federal Institute of Technology CH-1015 Lausanne Switzerland 3. PKU Green Chemistry Center Beijing National Laboratory for Molecular Sciences College of Chemistry and Molecular Engineering Peking University Beijing 100871 China

Recent developments of the synthesis and applications of functionalized ionic liquids (including dual-functionalized ionic liquids) have been highlighted in this review. Ionic liquids are at-tracting attention as alternative solvents in green chemistry, but as more functionalized ILs are pre-pared, a greater number of applications in increasingly diverse fields are found.

关键词： ionic liquids functionalized ionic liquids dual-functionallzed ionicliquids reaction media asymmetric synthesis nano-materials porous materials lubricants flue-gas desulfurization oil desul-furization

Construction of nonbinary quantum cyclic codes by using graph method

在线全文

学校读者我要写书评

暂无评论

Science in China(Series F) 2005年第6期48卷 693-702页

作者： LIU Tailin1,2,3. WEN Qiaoyan1 & LIU Zihui4 1. School of Science, beijing university of Posts and Telecommunications, beijing 100876, China 2. State Key Laboratory of Integrated Services Network, Xidian university, Xi’an 710071,China 3. Shandong Finance institute, Jinan 250014, China 4. School of Mathematical Sciences, peking university, beijing 100871, China 1. School of Science Beijing University of Posts and Telecommunications 100876 Beijing China 2. State Key Laboratory of Integrated Services Network Xidian University 710071 Xi’an China 3. Shandong Finance institute 250014 Jinan China 4. School of Mathematical Sciences Peking University 100871 Beijing China

Using the graph method proposed by Schlingemann and Werner, this paper introduces a technique to construct nonbinary quantum cyclic codes and provides a specific example. We also construct the quantum codes [[8, 2, 4]... 详细信息

关键词： nonbinary quantum stabilizer codes quantum cyclic codes

A novel compact low-power direct conversion receiver for mobile UHF RFID reader

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2012年第10期55卷 2226-2233页

作者： LIU Shan 1*,WANG Xin'An 1*,SHEN JinPeng 1,WANG Bo 1,YE Tao 2 & HUANG Ru 3.1 Key Laboratory of Integrated Microsystems,peking university Shenzhen Graduate School,Shenzhen 518055,China 2 Hong Kong R&D Centre for Logistics and Supply Chain Management Enabling Technologies,HongKong,China 3.institute of{3.,peking university,beijing 100871,China 1. Key Laboratory of Integrated Microsystems Peking University Shenzhen Graduate School Shenzhen 518055 China 2. Hong Kong R&D Centre for Logistics and Supply Chain Management Enabling Technologies HongKong China 3. institute of microelectronics Peking University Beijing 100871 China

A novel direct conversion receiver with low cost and low power is implemented in a 0.18 μm 1P6M standard CMOS process for a Mobile UHF RFID reader.A highly linear active mixer with low flicker noise and low noise active load is *** efficient and low cost on-chip DC offset voltage canceling scheme is adopted with a high-input-impedance four-input OPAMP to buffer the output of the DC offset canceller(DCOC) *** receiver has a measured input 1 dB compression point of 2 dBm and a sensitivity of 72 dBm in the presence of the large leakage signal from the *** occupying a silicon area of 2.5 mm 2 and consuming 21 mA from a 1.8 V supply,the receiver makes the mobile UHF RFID reader to communicate with a transponder in a distance of 1 m conveniently.

关键词： direct conversion receiver mobile UHF RFID reader low power DCOC active mixer four-input OPAMP

Skara hunanensis a new species of Skaracarida (Crustacea) from Upper Cambrian (Furongian) of Hunan,south China

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 2007年第8期17卷 934-942页

作者： Liu Jie Dong Xiping~(**) (School of Earth and Space Science,peking university,beijing{3.,China) [a]School of Earth and Space Science Peking University Beijing China

The fossils of Orsten-type preservation are as famous as Chengjiang Fauna in the world,but it was not until 2005 that the Orsten-type fossils represented by Skaraearida and Phosphatocopida were first reported to be found in western Hunan,South China. Here,we report the systematic paleontology of all the exquisitely preserved specimens belonging to *** were found at a same horizon of Upper Cambrian (Furongian) in Wangcun section,western Hunan,south China,assigned to a new species Skara huna- nensis *** hunanensis is characterized by small,soft-integumented,marine forms with slender,annulate body;labrum large and ventrocaudally directed;uniramous antennulae;biramous antennae and mandibulae;maxillas and maxillipeds of the same shape;all postantennular limbs join a short cephalic filter *** body has two tagmata:a cephalon with five pairs of well developed ap- pendages and a trunk composed of 11 ring-shaped conical segments.

关键词： Skara hunanensis Skaracarida Crustacea Upper Cambrian Furongian Hunan

Structure and optical properties of the Ge and Sn quantum-dots

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2000年第2期11卷 119-123页

作者： HAN Zhao-Hui ZHAO Zi-Qiang(institute of Heavy Ion Physics, Technical Physics Depariment, peking university,beijing{3.) 北京大学北京 100871

Embedded cluster samples Ge:CaF2 and Sn:CaF2 with different sizes less than 8nm were produced and their optical properties were *** diffraction reveals that the clusters’ structures are crystallites and compared with the bulk Germanium and Stannum, lattice constants expand about 4.7% in the case of Ge:CaF2 and 5.2% of Sn:CaF2. Optical absorption and photoluminescence spectra of these samples show good agreement with the Quantum-Confinement-Effect(QCE) theory. With the decreasing of the cluster’s size, the energy gap broadens and the absorption edge blueshift is observed, and the absorption edge also shifts with the changing of the fraction of Sn and Ge. The XPS results show that in the cluster state,the binding energy becomes higher.

关键词：锗微晶锡微晶半导体 X射线光电子能谱结构光学性质电子衍射氟化钙

Bifurcation stabilization of nonlinear systems by dynamic output feedback with application to rotating stall control

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2012年第1期55卷 200-213页

作者： CHEN PengNian1,QIN HuaShu2,WANG Yong3.HONG YiGuang2 1Department of Mathematics,China Jiliang university,Hangzhou 3.0018,China 2institute of Systems Science,The Chinese Academy of Sciences,beijing 100080,China 3.epartment of Mechanics,{3. university,beijing 100871,China 1. Department of Mathematics China Jiliang University Hangzhou 310018 China2. Institute of Systems Science The Chinese Academy of Sciences Beijing 100080 China3. Department of Mechanics Peking University Beijing 100871 China

The paper deals with the problem of stabilization of stationary bifurcation solutions of nonlinear systems via dynamic output *** is emphasized that the parameter of the system is not directly *** introduce the concepts of uniform observability of the inverse of a function of state and input and N-order-input-to-state bifurcation *** on the concepts,we propose a new method for designing dynamic compensators that guarantee bifurcation stability for the closed-loop *** an example,we apply the general theory to active control of rotating stall in axial flow compressors by designing a stabilizing dynamic compensator for the three-state Moore-Greitzer model with a class of cubic compressor characteristics.

关键词： bifurcation control uniform observability dynamic output feedback rotating stall

Unbounded Solutions of Almost Periodically Forced Pendulum-Type Equations

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2001年第3期17卷 391-396页

作者： Hai HUANG institute of Mathematical Sciences,peking university,{3. 100871.P.R.China E-mail:hhjq@*** institute of Mathematical Sciences Peking University Beijing 100871 P. R. China

In this paper,we prove that the forced pendulum-type equation +Gx（x,t）=p（t）,where G（x,t）∈C1（R2） with 1-periodicity in x satisfies the conditions:sup（x,t）∈R2|Gx（x,t）|t→∞{supx∈R|（Gt（x,t））/t|}=0,possesses infinitely many unbounded solutions on a cylinder S1×R for any almost periodic function p（t） with nonvauishing mean value.

关键词： Pendulum-type equation Instability Unbounded solution Almost periodic