检索结果-南通市图书馆

Sensorless Control of Permanent Magnet Synchronous Motor Based on New Sliding Mode Observer with Single Resistor Current Reconstruction

在线全文

学校读者我要写书评

暂无评论

CES Transactions on Electrical Machines and Systems 2022年第4期6卷 378-383页

作者： Qingguo Sun Xiaolei Zhu feng niu IEEE Hebei University of Technology

To solve the chattering problem caused by discontinuous switching function in traditional sliding mode observer,a piecewise square root switching function with continuously varying characteristics is designed,and its stability is analyzed by using Lyapunov stability ***,according to the relationship among bus current,switching state and phase current,a single bus resistance sampling current reconstruction scheme without current sensors is adopted,which effectively reduces the cost of motor ***,the feasibility and effectiveness of the proposed scheme are verified by simulation.

关键词： Permanent magnet synchronous motor New sliding mode observer Phase-locked loop Single resistor Current reconstruction

Characterization of Gallic Acid Interaction with Human Serum Albumin by Spectral and Molecular Modeling Methods

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2012年第2期28卷 287-290页

作者： LIU Zuo-jia LI Dan niu feng-lan School of Public Health Jilin UniversityChangchun 130021P.R.China

The binding of drugs with human serum albumin（HSA） is a crucial factor influencing the distribution and bioactivity of drugs in the *** understand the action mechanisms between gallic acid（GA,3,4,5-trihydroxybenzoic acid） and HSA,the binding of GA with HSA was investigated by a combined experimental and computational *** fluorescence properties of HSA and the binding parameters of GA collectively indicate that the binding is characterized by static quenching mechanism at one high affinity binding *** to the estimated molecular distance between the donor（HSA） and the acceptor（GA）,the binding is related to the fluorescence resonance energy *** indicated by the thermodynamic parameters,hydrophobic interaction plays a major role in the GA-HSA ***,the experimental results reveal that GA is bound in the large hydrophobic cavity of subdomain IIA in the site I of HSA,which is well approved by molecular docking.

关键词： Gallic acid Human serum albumin Fluorescence quenching Molecular modeling

Study of electrospray ionization tandem mass spectrometry of the benzofuranone compounds

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2008年第3期19卷 324-328页

作者： Zhan Qi niu Yu Min Sun feng niu Jian Han Da Wei Chen School of Pharmacy of Shenyang Pharmaceutical University Shenyang 110016 China ShiJiaZhuang Pharnta Group NBP Pharmaceutical Co. Ltd. Shijiazhuang 052160 China Department of Pharmaceutical Engineering School of Chemical EngineeringDalian University of Technology Dalian 116000 China Department of Natural Medicines School of Pharmaceutical Sciences Peking Universio Health Science Center Beijing 10008.3 China

A detailed analysis of benzofuranone compounds under multiple tandem mass spectrometry （ESI-MS^n） conditions is reported. Element composition data of the fragment ions were obtained with the aid of comparison of the multiple tandem mass spectra of four compounds, and the structures of which are identical except for some substituted groups or epimers or cis-trans-isomers. Attempts have been made to provide rational pathways for the formation of the fragment ions from these protonated compounds. And the structure-fragmentation relationships will facilitate the characterization of the structures of other analogs.

关键词： ESI-MS^n Benzofuranones Epimer: cis-trans-Isomer

Master event based backazimuth estimation and its application to downhole microseismic monitoring

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2022年第6期19卷 2675-2682页

作者： Xiao-Bo Meng Hai-Chao Chen feng-Lin niu Yi-Jing Du Department of Geophysics Chengdu University of TechnologyChengduSichuan610059China Unconventional Petroleum Research Institute and State Key Laboratory of Petroleum Resources and ProspectingChina University of PetroleumBeijing102249China Department of Earth Environmental and Planetary SciencesRice UniversityHoustonTX77005USA Petro China Research Institute of Petroleum Exploration and Development Beijing100083China

Microseismic monitoring provides a valuable tool for evaluating the effectiveness of hydraulic fracturing ***,robust detection and accurate location of microseismic events are challenging due to the low signal to noise ratio(SNR)of their signals on *** a downhole monitoring setting,P-wave polarization direction measured from 3-component records is usually considered as the backazimuth of the microseismic event,i.e.,the direction of the *** direction and arrival time difference between the P and S waves is used to locate the seismic *** SNR is low,an accurate estimate of event backazimuth becomes very challenging with the traditional covariance matrix *** we propose to employ a master event and use a grid search method to find the backazimuth of a target event that maximizes the dot product of the two backazimuthal vectors of the master and target *** compared the backazimuths measured with the proposed grid-search and the conventional covariance-matrix methods using a large synthetic *** found that the grid-search method yields more accurate backazimuth estimates from low SNR records when measurements are made at single geophone *** array data are combined,the proposed method also has some advantage over the covariance-matrix method,especially when the number of geophones is *** also applied the method to a microseismic dataset acquired by a hydraulic fracturing project at a shale play site in southwestern China and found that the relocated microseismic events tend to align along existing faults more tightly than those in the original catalog.

关键词： Hydraulic fracturing Microseismic event Back azimuth Master event Grid search Covariance-matrix

Feasibility analysis of 60Co production in pressurized water reactors

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2019年第10期30卷 21-29页

作者： Wei Zhang feng-Lei niu Ying Wu Zhang-Peng Guo Beijing Key Laboratory of Passive Safety Technology for Nuclear Energy North China Electric Power University

The radioactive isotope 60Co is used in many applications and is typically produced in heavy water *** most of the commercial reactors in operation are pressurized light water reactors(PWRs),the world supply of high level radioactive cobalt would be greatly increased if 60Co could be produced in ***,60Co production in PWRs has not been extensively studied;for the 59Co(n,c)60Co reaction,the positioning of 59Co rods in the reactor determines the rate of *** article primarily uses the models of 60Co production in Canadian CANDU power reactors and American boiling water reactors;based on relevant data from the pressurized water Daya Bay nuclear power plant,a PWR core model is constructed with the Monte Carlo N-Particle Transport Code;this model suggests changes to existing fuel assemblies to enhance 60Co *** addition,the plug rods are replaced with 59Co rods in the improved fuel assemblies in the simulation model to calculate critical parameters including the effective multiplication factor,neutron flux density,and distribution of energy *** considering different numbers of 59Co rods,the simulation indicates that different layout schemes have different impact levels,but the impact is not *** a whole,the components with four 59Co rods have a small impact,and the parameters of the reactor remain almost unchanged when four 59Co rods replace the secondary neutron ***,in theory,the use of a PWR to produce 60Co is feasible.

关键词： MCNP Fuel assembly Neutron flux Reactor power 60Co

Scalable high performance de-duplication backup via hash join

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science C(Computers and Electronics) 2010年第5期11卷 315-327页

作者： Tian-ming YANG Dan feng Zhong-ying niu Ya-ping WAN Wuhan National Laboratory for Optoelectronics School of Computer Science and Technology Huazhong University of Science and Technology Wuhan 430074 China

Apart from high space efficiency,other demanding requirements for enterprise de-duplication backup are high performance,high scalability,and availability for large-scale distributed *** main challenge is reducing the significant disk input/output(I/O) overhead as a result of constantly accessing the disk to identify duplicate *** inline de-duplication approaches mainly rely on duplicate locality to avoid disk bottleneck,thus suffering from degradation under poor duplicate locality *** paper presents Chunkfarm,a post-processing de-duplication backup system designed to improve capacity,throughput,and scalability for *** performs de-duplication backup using the hash join algorithm,which turns the notoriously random and small disk I/Os of fingerprint lookups and updates into large sequential disk I/Os,hence achieving high write throughput not influenced by workload *** importantly,by decentralizing fingerprint lookup and update,Chunkfarm supports a cluster of servers to perform de-duplication backup in parallel;it hence is conducive to distributed implementation and thus applicable to large-scale and distributed storage systems.

关键词： Backup system De-duplication Post-processing Fingerprint lookup Scalability

Synthesis of the Biomimetic Polymer: Aliphatic Diamine and RGDS Modified Poly(d,l-lactic acid)

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2005年第8期16卷 1035-1038页

作者： Xu feng niu Yuan Liang WANG Yan feng LUO Jun PAN Li Xia GUO Key Lab of Biomechanics ＆ Tissue Engineering （Chongqing University） Ministry of Education Bioengineering College of Chongqing University Chongqing 400044

A novel poly（d, /-lactic acid）（PDLLA） based biomimetic polymer was synthesized by grafting maleic anhydride, butanediamine and arg-gly-asp-ser （RGDS） peptides onto the backbone of PDLLA, aiming to overcome the acidity and auto-accelerating degradation of PDLLA during degradation and to improve its biospecificity and biocompatibility. The synthetic copolymer was characterized by FTIR, ^13C NMR and amino acid analyzer （AAA）.

关键词： Poly(d,l-lactic acid) maleic anhydride butanediamine arg-gly-asp-ser modification.

Feasibility of underground NPP and its MCDA-based optimization

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2016年第4期27卷 89-95页

作者： Hou-Bo Qi feng-Lei niu Yun-Gan Zhao Yu Yu Sheng-Fei Wang Beijing Key Laboratory of Passive Safety and Technology on Nuclear Energy North China Electric Power University

The underground nuclear power plant(NPP)makes full use of land resources, reduces costs, makes better use of its passive safety, and avoids radioactivity release into the atmosphere in serious nuclear *** this paper, for obtaining comprehensive and integrated analyses on this new NPP design, we introduce four kinds of underground NPP designs, analyze the feasibility of each design from various aspects, and use the multiple criteria decision analysis method to choose the best option.

关键词：核电站资源优化决策分析方法电厂设计放射性释放土地资源被动安全最佳方案

Offlattice Model in the Prediction of Protein 3D Structure

在线全文

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 2007年第2期12卷 235-238页

作者： SHI feng LI Nana niu Xiaohui School of Science Huazhong Agricultural University Wuhan 430070 Hubei China

3-dimension HPNX offiattice model is developed from the 2-dimension HP offiattice model. In the HP model, 20 types of amino acid monomers are divided into two classes, H （non-polar monomer） and P （polar monomer）. In the HPNX model, polar monomers are split into positively charged （P）, negatively charged （N） and neutral （X） monomers. A new evolutionary algorithm is applied to study long chains of the HPNX offiattice protein model. This method successfully predict the structures of several proteins in the 3-dimension space that are similar to the structures gotten by X-Ray Crystallography and NMR and published in the PDB（Protein Data Bank）.

关键词： offlattice protein folding 3D structure