检索结果-南通市图书馆

Iterative Methods for Solving the Nonlinear Balance Equation with Optimal Truncation

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2021年第5期38卷 755-770页

作者： Qin XU jie cao NOAA/National Severe Storms Laboratory NormanOklahoma 73069USA Cooperative Institute for Mesoscale Meteorological Studies University of OklahomaNormanOklahoma 73072USA Institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029China

Two types of existing iterative methods for solving the nonlinear balance equation(NBE)are *** the first type,the NBE is rearranged into a linearized equation for a presumably small correction to the initial guess or the subsequent updated *** the second type,the NBE is rearranged into a quadratic form of the absolute vorticity with the positive root of this quadratic form used in the form of a Poisson equation to solve NBE *** two methods are rederived by expanding the solution asymptotically upon a small Rossby number,and a criterion for optimally truncating the asymptotic expansion is proposed to obtain the super-asymptotic approximation of the *** each rederived method,two iterative procedures are designed using the integral-form Poisson solver versus the over-relaxation scheme to solve the boundary value problem in each *** testing with analytically formulated wavering jet flows on the synoptic,sub-synoptic and meso-αscales,the iterative procedure designed for the first method with the Poisson solver,named M1a,is found to be the most accurate and *** the synoptic wavering jet flow in which the NBE is entirely elliptic,M1a is extremely *** the sub-synoptic wavering jet flow in which the NBE is mostly elliptic,M1a is sufficiently *** the meso-αwavering jet flow in which the NBE is partially hyperbolic so its boundary value problem becomes seriously ill-posed,M1a can effectively reduce the solution error for the cyclonically curved part of the wavering jet flow,but not for the anti-cyclonically curved part.

关键词： nonlinear balance iterative method optimal truncation

Numerical simulation of gas migration into mining-induced fracture network in the goaf

在线全文

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2017年第4期27卷 681-685页

作者： cao jie Li Wenpu State Key Laboratory of Gas Disaster Detection Prevention and Emergency Control. Chongqing 400037. China Chongqing Research Institute Co. Ltd. of China Coal Technology and Engineering Group Chongqing 400037 China State Key Laboratory of Coal Mine Disaster Dynamics and Control. Chongqing University. Chongqing 400044 China

Gas extraction practice has been proven for the clear majority of coal mines in China to be unfavorable using drill holes in the coal seam. Rather, mining-induced fractures in the goaf should be utilized for gas extraction. To study gas migration in mining-induced fractures, one mining face of 10 th Mine in Pingdingshan Coalmine Group in Henan, China, has been selected as the case study for this work. By establishing the mathematical model of gas migration under the influence of coal seam mining, discrete element software UDEC and Multiphysics software COMSOL are employed to model gas migration in mining-induced fractures above the goaf. The results show that as the working face advances, the goaf overburden gradually forms a mining-induced fracture network in the shape of a trapezoid, the size of which increases with the distance of coal face advance. Compared with gas migration in the overburden matrix, the gas flow in the fracture network due to mining is far greater. The largest mining-induced fracture is located at the upper end of the trapezoidal zone, which results in the largest gas flux in the network. When drilling for gas extraction in a mining-induced fracture field, the gas concentration is reduced in the whole region during the process of gas drainage, and the rate of gas concentration drops faster in the fractured zone. It is shown that with gas drainage, the gas flow velocity in the mininginduced fracture network is faster.

关键词： Gas migration Fractures Mining-induced Numerical simulation

Preparation mechanism,physical characteristic and antitumor activity of nano-scheelite

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2009年第4期16卷 468-474页

作者： Lin cao Fu-qiang Yang jie-xin cao School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Peking University Health Science Center Beijing 100083 China

After preparing the EU^3＋-doped scheelite nano-material by Pechini method with the nanoparticles of 30-50 nm in diameter, X-ray diffraction （XRD）, transmission electron microscopy （TEM） and high resolution transmission electron microscopy （HRTEM） were used to show a microcosmic description of the particle morphology and crystal structure. The spectrum signature of the nano-scheelite, which was taken by fluorescence spectrometer, was used to discuss the difference of luminescent performance between the nano-scheelite and bulk scheelite. The atomic site of the nano-scheelite was intuitively shown through HRTEM images and HRTEM simulated images from the relation between luminescent properties and crystal structure, which was analyzed by spectrum probe. The results of antitumor activity examined by the 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide （MTT） method show that the inhibition of human promyelocytic leukemia cell line （HL60） is enhanced immediately with increasing the concentration and presents a reliance on the quantity. The results of fluorescence spectra and structure show that the antitumor activity has something to do with micro-structure and surface charge.

关键词： scheelite fluorescence spectrum atomic site anti-tumor activity

Integrating OWA and Data Mining for Analyzing Customers Churn in E-Commerce

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2015年第2期28卷 381-392页

作者： cao jie YU Xiaobing ZHANG Zhifei Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science & Technology Information Center of Jiangsu Province

Customers are of great importance to E-commerce in intense *** is known that twenty percent customers produce eighty percent ***,how to find these customers is very *** lifetime value(CLV) is presented to evaluate customers in terms of recency,frequency and monetary(RFM) variables.A novel model is proposed to analyze customers purchase data and RFM variables based on ordered weighting averaging(OWA) and K-Means cluster *** is employed to determine the weights of RFM variables in evaluating customer lifetime value or loyalty.K-Means algorithm is used to cluster customers according to RFM *** customers could be found out by comparing RFM values of every cluster group with average *** is conducted to investigate which reasons cause customers *** these reasons to help E-commerce improve *** experimental results have demonstrated that the model is effective and reasonable.

关键词： Customer life value E-commerce K-means OWA.

Ensemble relation network with multi-level measure

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2022年第3期29卷 15-24,33页

作者： Li Xiaoxu Qu Xue cao jie College of Computer and Communication Lanzhou University of TechnologyLanzhou 730050China College of Electrical and Information Engineering Lanzhou University of TechnologyLanzhou 730050China Engineering Research Center of Urban Railway Transportation of Gansu Province Lanzhou 730050China

Fine-grained few-shot learning is a difficult task in image classification. The reason is that the discriminative features of fine-grained images are often located in local areas of the image, while most of the existing few-shot learning image classification methods only use top-level features and adopt a single measure. In that way, the local features of the sample cannot be learned well. In response to this problem, ensemble relation network with multi-level measure(ERN-MM) is proposed in this paper. It adds the relation modules in the shallow feature space to compare the similarity between the samples in the local features, and finally integrates the similarity scores from the feature spaces to assign the label of the query samples. So the proposed method ERN-MM can use local details and global information of different grains. Experimental results on different fine-grained datasets show that the proposed method achieves good classification performance and also proves its rationality.

关键词： fine-grained image classification few-shot learning local feature learning metric learning

Characterization of polyoxometalates by electrospray ionization mass spectrometry

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 Chemistry 2015年第7期58卷 1206-1210页

作者： Qiaodi Jia Yan Zhang jie cao Key Laboratory of Cluster Science Ministry of Education of China Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials School of Chemistry Beijing Institute of Technology

The electrospray behaviors of saturated, substituted, and lacunary polyoxometalates （POMs） with classic Keggin and Dawson structures were investigated systematically by electrospray mass spectrometry （ESI-MS）. The anions included Keggin [SiW12O40]4-, [SiW11O39]8-, [SiW10O36]8 , [SiW9O34]10-, Dawson [P2W18O62]6-, [P2W17O61]10-, and metal-substituted Keggin derivatives such as [PW11MnO40]7-, [SiW10V2O40]6-, and [GeWgCu3O37]10-. Common species observed in the mass spectra arose from the protonation or cationization of either intact or dehydrated precursor ions. Compared to saturated and substituted POMs, lacunary POMs exhibited distinguished MS behaviors such as a much higher degree of cationization and dehydration of the bare polyoxoanions present in the mass spectra. In addition, some of these lacunary POMs were found to undergo subtle speciation change in solution. Freshly prepared solutions are suggested for synthetics for which lacunary POMs are starting materials. The advantages of the cation-exchange process which are prior to MS analysis are illustrated by an example.

关键词： saturated substituted and lacunary POMs electrospray ionization mass spectrometry cation-ion exchange process

Fast prediction for multi-parameters(concentration,temperature and humidity)of indoor environment towards the online control of HVAC system

在线全文

学校读者我要写书评

暂无评论

Building Simulation 2021年第3期14卷 649-665页

作者： Hao-Cheng Zhu Chen Ren Shi-jie cao School of Architecture Southeast University2 SipailouNanjing27009China Global Centre for Clean Air Research(GCARE) Department of Civil and Environmental EngineeringFaculty of Engineering and Physical SciencesUniversity of SurreyGuildfordSurreyUK Academy of Building Energy Efficiency School of Civil EngineeringGuangzhou UniversityGuangzhou 570006China

Heating,ventilation and air conditioning(HVAC)systems are the most energy-consuming building implements for the improvement of indoor environmental quality(IEQ).We have developed the optimal control strategies for HVAC system to respectively achieve the optimal selections of ventilation rate and supplied air temperature with consideration of energy conservation,through the fast prediction methods by using low-dimensional linear ventilation model(LLVM)based artificial neural network(ANN)and low-dimensional linear temperature model(LLTM)based contribution ratio of indoor climate(CRI_((T))).To be continued for integrated control of multi-parameters,we further developed the fast prediction model for indoor humidity by using low-dimensional linear humidity model(LLHM)and contribution ratio of indoor humidity(CRI_((H))),and thermal sensation index(TS)for *** was used to construct the prediction database for CO_(2),temperature and ***-dimensional linear models(LLM),including LLVM,LLTM and LLHM,were adopted to expand database for the sake of data storage ***,coupling with ANN,CRI_((T)) and CRI_((H)), the distributions of indoor CO_(2) concentration,temperature,and humidity were rapidly predicted on the basis of LLVM-based ANN,LLTM-based CRIm and LLHM-based CRM ***,according to the self-defined indices(i.e.,E_(V),E_(T),E_(H)),the optimal balancing between IEQ(indicated by CO_(2) concentration,PMV and TS)and energy consumption(indicated by ventilation rate,supplied air temperature and humidity)were synthetically *** total HVAC energy consumption could be reduced by 35%on the strength of current control *** work can further contribute to development of the intelligent online control for HVAC systems.

关键词： HVAC system indoor air pollution thermal comfort indoor humidity control

The nonlocal transport and switch effect in light-and electric-controlled silicene–superconductor hybrid structure

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 Physics B 2018年第12期27卷 121-126页

作者： Fenghua Qi Jun cao jie cao Lifa Zhang Center for Quantum Transport and Thermal Energy Science School of Physics and TechnologyNanjing Normal UniversityNanjing 210023China School of Electronic Engineering Nanjing Xiaozhuang UniversityNanjing 211171China College of Science Hohai UniversityNanjing 210098China

We theoretically investigate the influence of off-resonant circularly polarized light field and perpendicular electric field on the quantum transport in a monolayer silicene-based normal/superconducting/normal *** to the tunable band structure of silicene,a pure crossed Andreev reflection process can be realized under the optical and electrical ***,a switch effect among the exclusive crossed Andreev reflection,the exclusive elastic cotunneling and the exclusive Andreev reflection,where the former two are the nonlocal transports and the third one is the local transport,can be obtained in our system by the modulation of the electric and light *** addition,the influence of the relevant parameters on the nonlocal and local transports is calculated and analyzed as well.

关键词： switch effect silicene crossed Andreev reflection

A novel robust design method for improving stability of optimized structures

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2015年第1期31卷 104-111页

作者： Ming-jie cao Hai-Tao Ma Peng Wei State Key Laboratory of Subtropical Building Science Department of Civil Engineering South China University of Technology State Key Laboratory of Structural Analysis of Industrial Equipment Dalian University of Technology

It is known that structural optimization may lead to designs of structures having low stability and sometimes even kinematically unstable designs. This paper presents a robust design method for improving the stability of opti mized structures. A new approach is proposed, in which cer tain perturbation loads are introduced and the corresponding compliance is added to the objective function as a penaliza tion. The stability of the optimized structures can thus be improved substantially by considering structural responses to the original and the introduced loads. Numerical exam ples show the simplicity and effectiveness of the proposed method.

关键词： Structural optimization Robust design Penal-ization Perturbation loads