检索结果-南通市图书馆

A Nonmonotone Hybrid Method of Conjugate Gradient and Lanczos-type for Solving Nonlinear Systems

在线全文

学校读者我要写书评

暂无评论

Journal of the Operations Research Society of China 2014年第3期2卷 291-305页

作者： Chun-Xia Jia Jue-Yu Wang De-tong zhu Department of Mathematics Shanghai Normal UniversityShanghai 200234China Department of Mathematics Shanghai Normal UniversityGuilin Road 100Shanghai 200234China

In this paper,we construct a new algorithm which combines the conjugate gradient and Lanczos methods for solving nonlinear *** iterative direction can be obtained by solving a quadratic model via conjugate gradient and Lanczos *** the backtracking line search,we will find an acceptable trial step size along this direction which makes the objective function nonmonotonically decreasing and makes the norm of the step size monotonically *** convergence and local superlinear convergence rate of the proposed algorithm are established under some reasonable ***,we present some numerical results to illustrate the effectiveness of the proposed algorithm.

关键词： Nonmonotonic technique Nonlinear systems Lanczos method Conjugate gradient

Synthesis and Crystal Structure of 4-(4-Bromophenyl)- 3,4-dihydro-6-methyl quinolin-2(1H)-one

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

Chinese Journal of Structural Chemistry 2007年第5期26卷 533-536页

作者： YU Chen-Xia zhu Xiao-tong YAO Chang-Sheng TU Shu-Jiang Department of Chemistry Xuzhou Normal University Xuzhou 221116 China Key Laboratory of Biotechnology for Medical Plants of Jiangsu Province Xuzhou 221116 China

The title compound （C16H14BrNO） has been synthesized by the reaction of p-tolylamine, Meldrum’s acid and 4-bromo-benzaldehyde, and its structure was characterized by IR, 1H NMR and X-ray single-crystal diffraction. The crystal belongs to monoclinic, space group P21/n with a = 7.6850（11）, b = 8.3004（11）, c = 21.301（3）A, β = 95.110（2）°, V = 1353.4（3） A^3, Mr = 316.19, Z = 4, Dc = 1.552 g/cm^3, μ（MoKα） = 3.028 mm-1, F（000） = 640, the final R = 0.0345 and wR = 0.0768. X-ray analysis reveals that the atoms of C（1）, C（2）, C（3）, C（4）, C（5） and N（1） form a six-membered ring of boat conformation.

关键词： quinoline crystal structure

Water-soluble ions in hailstones in northern and southwestern China

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2018年第18期63卷 1177-1179页

作者： Xiaofei Li Qinghong Zhang tong zhu Zejun Li Jipei Lin Tian Zou Department of Atmospheric and Oceanic Sciences School of Physics Peking University Beijing 100871 China SKL-ESPC and BIC-ESAT. College of Environmental Sciences and Engineering Peking University Beijing 100871 China National Laboratory for Molecular Sciences Radiochemistry and Radiation Chemistry Key Laboratory of Fundamental Science College of Chemistry and Molecular Engineering Peking University Beijing 100871 China

Natural hailstones were collected and analyzed in the laboratory not only for their physical properties (e.g., structure, density,shape, and air bubbles), but also for their chemical properties(e.g., organic particles, biological particles, and water-soluble ions),which can help a clear understanding on microphysics and development of hailstorms [1–4]. Aerosol particles were carried up from the atmospheric boundary layer to the free atmosphere into

关键词：水溶性冰雹离子中国西南生物粒子物理性质化学性质

Experimental and numerical study on improvement performance by wave parallel flow field in a proton exchange membrane fuel cell

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2022年第5期35卷 90-102页

作者： Zijun Li Shubo Wang Sai Yao Xueke Wang Weiwei Li tong zhu Xiaofeng Xie School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China Institute of Nuclear and New Energy Technology Tsinghua UniversityBeijing 100084China Beijing Institute of Space Launch Technology Beijing 100076China

The performance and operation stability of proton exchange membrane fuel cells(PEMFCs)are closely related to the transportation of reactants and water management in the membrane electrode assembly(MEA)and flow *** this paper,a new three-dimensional wave parallel flow field(WPFF)in cathode was designed and analyzed throughout simulation studies and an experimental *** experimental results show that the performance of PEMFC with WPFF outperforms that of PEMFC with straight parallel flow field(SPFF).Specifically,the peak power density increased by 13.45%for the PEMFC with WPFF as opposed to PEMFC with *** addition,the flow field with area of 11.56 cm^(2) was formed by the assembly of transparent end plate used for cathode and the traditional graphite plate used for *** understand the mechanism of the novel flow field improving the performance of PEMFC,a model of PEMFC was proposed based on the geometry,operating conditions and MEA *** thickness of gas diffusion layers(GDL),catalytic layers(CL)and proton exchange membrane were measured by scanning electron *** simulation result shows that compared with SPFF,the WPFF based PEMFC promote the oxygen transfer from flow channel to the surface of CL through GDL,and it was beneficial to remove the liquid water in the flow channel and the MEA.

关键词： Fuel cells Transport process Computational fluid dynamics Flow regimes Water management

Polarization resolved analysis of phonon transport in a multi-terminal system

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2019年第12期28卷 208-214页

作者： Yun-Feng Gu Liu-tong zhu Xiao-Li Wu College of Electronic and Mechanical Engineering Nanjing Forestry UniversityNanjing210037China

The atomistic Green’s function method is improved to compute the polarization resolved phonon transport in a multiterminal system. Based on the recent developments in literature, the algorithm is simplified. The complex phonon band structure of a semi-infinite periodic terminal is obtained by the generalized eigenvalue equation. Then both the surface Green’s function and phonon group velocity in the terminal are determined from the wave modes propagating away from the scattering region along the terminal. With these key ingredients, the individual phonon mode transmittance between the terminals can be calculated. The feasibility and validity of the method are demonstrated by the chain example compared with the wave packet method, and an example of graphene nanojunction with three terminals.

关键词： Green’s function method phonon transport multi-terminal systems

Geochemical characteristics of noble gases in natural gas and their application in tracing natural gas migration in the middle part of the western Sichuan Depression, China

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2013年第3期10卷 327-335页

作者： Wang Peng Shen Zhongmin Liu Sibing Lv Zhengxiang zhu tong Gong Yajun State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Chengdu University of Technology Geology Scientific Research Institute of Shengli Oilfield Branch Company SINOPEC

Noble gases in natural gas, from Xiaoquan, Xinchang, Hexingchang and Fenggu gas reservoirs in the middle part of the western Sichuan Depression, China, were analysed. Results show that the volume content of crustal noble gases accounts for 97.9% to 99.7% of the total noble gas content, indicating that the noble gases in the study area are very largely derived from the crust. Moreover, the 40Ar time-accumulating effect of source rocks is used to determine the complex relationship between gases and source rocks in this area, and the results agree well with that from analysis of source rock light hydrocarbons. Due to the short migration distance, the separation of 4He and 40Ar is not significant in Xujiahe natural gas and Lower and Middle Jurassic natural gas, so it is difficult to trace natural gas migration. However, this separation characteristic of 4He and 40Ar in Middle and Upper Jurassic natural gas is significant, which indicates that natural gas migration was from the Middle Jurassic to Upper Jurassic formations. In addition, the variation trends of 3He/4He ratio and δ13C1 value indicates that natural gas migration is from the Xujiahe formation to the Jurassic layer in the study area.

关键词： Western Sichuan Depression noble gas He and Ar isotopes natural gas migration

Heterogeneous reaction of NO_2 on the surface of montmorillonite particles

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2012年第10期24卷 1753-1758页

作者： Zefeng Zhang Jing Shang tong zhu Hongjun Li Defeng Zhao Yingju Liu Chunxiang Ye College of Environmental Sciences and Engineering Peking UniversityBeijing 100871China CMA Key Laboratory for Atmospheric Physics and Environment Nanjing University of Information Science and TechnologyNanjing 210044China

The studies on heterogeneous reactions over montmorillonite, which is a typical 2：1 layered aluminosilicate, will benefit to the Understanding of heterogeneous reactions on clay minerals. Montmorillonite can be classified as sodium montmorillonite or calcium montmorillonite depending on the cation presented between the different layers. Using diffuse reflectance infrared Fourier transform spectroscopy （DRIFTS）, the heterogeneous reaction mechanism of NO2 on the surface of montmorillonite was firstly investigated. Results showed that the reaction of NO2 on the surface of sodium and calcium montmorillonite fit a first-order kinetics, and the reaction duration of calcium montmorillonite was longer than that of sodium montmorillonite under the dry condition. For either sodium or calcium montmorillonite, the uptake coefficient decreased as humidity increased.

关键词： heterogeneous reaction uptake coefficient DRIFTS montmorillonite NO2

Role of secondary aerosols in haze formation in summer in the Megacity Beijing

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2015年第5期27卷 51-60页

作者： Tingting Han Xingang Liu Yuanhang Zhang Yu Qu Limin Zeng Min Hu tong zhu State Key Laboratory of Water Environment Simulation School of Environment Beijing Normal University State Key Joint Laboratory of Environment Simulation and Pollution Control College of Environmental Sciences and Engineering Peking University State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of Sciences

A field experiment from 18 August to 8 September 2006 in Beijing, China, was carried out. A hazy day was defined as visibility 〈 10 km and RH（relative humidity）〈 90%. Four haze episodes, which accounted for ～ 60% of the time during the whole campaign, were characterized by increases of SNA（sulfate, nitrate, and ammonium） and SOA（secondary organic aerosol） concentrations. The average values with standard deviation of SO2-＋4, NO-3, NH4 and SOA were 49.8（± 31.6）, 31.4（±22.3）, 25.8（±16.6） and 8.9（±4.1） μg/m3, respectively, during the haze episodes, which were 4.3, 3.4, 4.1, and 1.7 times those in the non-haze days. The SO2-4,NO-3, NH＋4, and SOA accounted for 15.8%, 8.8%, 7.3%, and 6.0% of the total mass concentration of PM10 during the non-haze days. The respective contributions of SNA species to PM10 rose to about27.2%, 15.9%, and 13.9% during the haze days, while the contributions of SOA maintained the same level with a slight decrease to about 4.9%. The observed mass concentrations of SNA and SOA increased with the increase of PM10 mass concentration, however, the rate of increase of SNA was much faster than that of the SOA. The SOR（sulfur oxidation ratio） and NOR（nitrogen oxidation ratio） increased from non-haze days to hazy days, and increased with the increase of RH. High concentrations of aerosols and water vapor favored the conversion of SO2 to SO2-4and NO2 to NO-3, which accelerated the accumulation of the aerosols and resulted in the formation of haze in Beijing.

关键词： Secondary inorganic aerosols Secondary organic aerosols Haze formation Sulfur oxidation ratio Nitrogen oxidation ratio

A Prior Information Enhanced Extraction Framework for Document-level Financial Event Extraction

在线全文

学校读者我要写书评

暂无评论

Data Intelligence 2021年第3期3卷 460-476页

作者： Haitao Wang tong zhu Mingtao Wang Guoliang Zhang Wenliang Chen School of Computer Science and Technology Soochow UniversitySuzhou 215006China

Document-level financial event extraction(DFEE) is the task of detecting events and extracting the corresponding event arguments in financial documents, which plays an important role in information extraction in the financial domain. This task is challenging as the financial documents are generally long text and event arguments of one event may be scattered in different sentences. To address this issue, we proposed a novel Prior Information Enhanced Extraction framework(PIEE) for DFEE, leveraging prior information from both event types and pre-trained language models. Specifically, PIEE consists of three components: event detection, event argument extraction, and event table filling. In event detection, we identify the event type. Then, the event type is explicitly used for event argument extraction. Meanwhile, the implicit information within language models also provides considerable cues for event arguments localization. Finally, all the event arguments are filled in an event table by a set of predefined heuristic rules. To demonstrate the effectiveness of our proposed framework, we participated in the share task of CCKS2020 Task 4-2: Documentlevel Event Arguments Extraction. On both Leaderboard A and Leaderboard B, PIEE took the first place and significantly outperformed the other systems.

关键词： Event extraction Information extraction Financial event Event detection Event argument extraction