检索结果-南通市图书馆

Optimal midcourse trajectory planning considering the capture region

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2018年第3期29卷 587-600页

作者： ZHOU Jin SHAO lei WANG Huaji ZHANG Dayuan lei Humin Air and Missile Defense College Air Force Engineering UniversityXi'an 710051China Unit 95948 of the PLA Jiuquan 732750China

An optimal midcourse trajectory planning approach that considers the capture region（CR） of the terminal guidance is proposed in this article based on the Gauss pseudospectral method（GPM）. Firstly, the planar CR of the proportional navigation in terminal guidance is analyzed and innovatively introduced in the midcourse trajectory planning problems, with the collision triangle（CT） serving as the ideal terminal states parameters of the midcourse phase, and the CR area serving as the robustness against target maneuvers. Secondly, the midcourse trajectory planning problem that considers the path, terminal and control constraints is formulated and the well-developed GPM is used to generate the nominal trajectory that meets the CR demands. The interceptor will reshape the trajectory only when the former CR fails to cover the target, which has loosened the critical demand for frequent trajectory modification. Finally, the simulations of four different scenarios are carried out and the results prove the effectiveness and optimality of the proposed method.

关键词： capture region(CR) collision triangle(CT) midcourse guidance trajectory planning hypersonic interception trajectory modification

A Novel Construction Approach of Irregular LDPC Codes Based on QC Structure and Zigzag Pattern

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2015年第4期24卷 783-789页

作者： lei Jing YAO Chunguang CHEN Bin WEN lei LIU Wei College of Electronic Science and Engineering National University of Defense Technology

This paper presents a novel construction method of irregular Low-density parity-check(LDPC)codes based on Quasi-cyclic(QC) structure and zigzag pattern. By using the proposed method, a class of irregular and highly structured LDPC codes can be designed with the advantages of low storage requirement and linear time encoding complexity. The constructed codes are called Irregular repeat-accumulate like(IRA-like) codes since their parity-check matrices are similar with those of IRA codes,which all contain a sparse zigzag pattern submatrix. The left part of the parity-check matrix of IRA-like codes is a kind of circulant permutation matrix. A best-effort analyzing method for optimizing the cycle structure of IRAlike codes is presented. We further details the proper constraints for avoiding short cycles and low-weight codewords. Simulation results show that the proposed IRA-like codes have low encoding complexity, good iterative decoding performance and flexible choice of code parameters.

关键词： LDPC codes QC structure Zigzag pattern IRA-like codes

A phenomenological description of moisture capacity of iron ores

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Particuology 2012年第6期10卷 692-698页

作者： Xuewei Lv Qiugang Yuan Chenguang Bai Xiaobo Huang lei lei School of Materials Science and Engineering Chongqing University

Moisture capacity of iron ore, defined as its ability to hold water, has been found to be attected by Its particle size and chemical composition. To explain this phenomenon, mathematical model was developed on the basis of particle size, specific surface area, pore properties and contact angle between the iron ore and water. The specific surface area and the pore volume of iron ores were measured to validate the model, and parametric studies were carried out to investigate the effects of these factors, showing that particle size and surface area of the iron ore and thickness of the water film are the principal factors determining the moisture capacity. The model gave reasonable explanation of the phenomenon that moisture capacity increases with decreasing particle size. A correlation developed can well predict the moisture capacity of iron ores. Deviations between measurements and calculations were analyzed.

关键词： Mathematical modelIron oreMoisture capacityWater contentGranulation

Terminal-selective C（sp3）–H borylation of unbranched alkanes enabled by intermolecular radical sampling and LMCT photocatalysis

在线全文

学校读者我要写书评

暂无评论

National Science Review 2024年第5期11卷 96-98页

作者： Zhexuan lei Jie Wu Department of Chemistry National University of Singapore

The selective functionalization of C（sp3）–H bonds with subtle differences in alkanes is highly sought after due to its atom-and step-efficiency. The activation of C（sp3）–H bonds through hydrogen atom transfer （HAT） has been extensively exploited to produce a valueadded product from unfunctionalized material [1,2].

关键词：

Characterization of synergistic anti-tumor effects of doxorubicin and p53 via graphene oxide-polyethyleneimine nanocarriers

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2017年第8期33卷 807-814页

作者： Bei Xie Jipeng Yi Jian Peng Xing Zhang lei lei Dapeng Zhao Zhixin lei Hemin Nie Institute of Bionanotechnology and Tissue Engineering College of Life SciencesHunan UniversityChangsha 410082China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Department of Orthodontics Xiangya Stomatological HospitalCentral South UniversityChangsha 410008China Changsha DMY Medical Technology Co.Ltd Changsha 410005China Shenzhen Research Institute of Hunan University Nanshan Hi-new Technology and Industry ParkShenzhen 518057China

Co-delivery of chemical drugs and therapeutic genes for synergistic therapy provides a promising strategy to treat devastating diseases. However, the real-time coordination patterns between chemical drugs and therapeutic genes remain poorly understood. Herein, the complexes of doxorubicin/graphene oxidepolyethyleneimine/p53 plasmid（Dox/GO-PEI/p53） were fabricated and employed to investigate the synergistic manner between Dox and p53 in the inhibition of He La cell growth. GO was conjugated with PEI to form the GO-PEI backbone as the delivery vector. The GO backbone provided surfaces with a high specific area to load Dox via the π-π stacking interaction, and was able to release Dox significantly faster at pH 5.0 than at pH 7.0, while the positively charged PEI section of GO-PEI could condense plasmids into GO-PEI/DNA nanoparticles via the electrostatic interaction. The nanoparticles efficiently mediated the transfection of DNA in He La cells, with lower cytotoxicity compared to PEI/DNA nanoparticles. Furthermore, the complexes of Dox/GO-PEI/p53 released Dox and expressed p53 gene in a sequential manner,and showed successive inhibition of the in vitro growth of He La cells. This type of drug/GO-PEI/DNA complex can be employed as a platform to investigate the coordination pattern between chemical drugs and therapeutic genes for tumor therapy.

关键词： Graphene oxide Polyethyleneimine Doxorubicin p53 Successive inhibition

First-Principles Study of La Doping Effects on the Electronic Structures and Photocatalytic Properties of Anatase TiO2

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Physics 2015年第6期28卷 -页

作者： Ping Huang Bo Shang Ling-jie Li Jing-lei lei School of Chemistry and Chemical Engineering Chongqing University Chongqing 400044 China

The effects of doping concentration, position and oxygen vacancy defect on the stability, electronic and optical properties of La-doped anatase TiO2 have been investigated based on DFT+U method. The calculations indicated that the doping concentration and sites of La affected the stability and band gap of La-doped TiO2 significantly due to the lattice distortion, which obey the ionic Pauling's rules and crystal field theories; moreover, the simulated adsorptionspectrum shows an obviously increase in the photocatalysis properties, which are in good agreement with recently experimental measurements. The oxygen vacancy defect will enhance the structural stability and the adsorption of visible light in La-doped TiO2 system, which is important in photocatalytic application.

关键词： Density functional theory La doping Anatase TiO2 Oxygen vacancy

3D full-loop simulation and experimental verification of gas-solid flow hydrodynamics in a dense circulating fluidized bed

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

Particuology 2014年第5期12卷 218-226页

作者： Xueyao Wang Xuezhi Wu Fulin lei Jing lei Yunhan Xiao Key Laboratory of Advanced Energy and Power Institute of Engineering Thermophysics Chinese Academy of Sdences Beijing 100190 China Research Center for Clean Energy and Power Chinese Academy of Sciences Lianyungang Jiangsu 222069 China School of Energy & Power Engineering North China Electric Power University Changping District Beijing 102206 China

Because of their advantages of high efficiency and low cost, numerical research methods for large-scale circulating fluidized bed （CFB） apparatus are gaining ever more importance. This article presents a numer- ical study of gas-solid flow dynamics using the Eulerian granular multiphase model with a drag coefficient correction based on the energy-minimization multi-scale （EMMS） model. A three-dimensional, full-loop, time-dependent simulation of the hydrodynamics of a dense CFB apparatus is performed. The process parameters （e.g., operating and initial conditions） are provided in accordance with the real experiment to enhance the accuracy of the simulation. The axial profiles of the averaged solid volume fractions and the solids flux at the outlet of the cyclone are in reasonable agreement with experimental data, thereby verifying the applicability of the mathematical and physical models. As a result, the streamline in the riser and standpipe as well as the solids distribution contours at the cross sections is analyzed. Computational fluid dynamics （CFD） serves as a basis for CFB modeling to help resolve certain issues long in dispute but difficult to address experimentally. The results of this study provide the basis of a general approach to describing dynamic simulations of gas-solid flows.

关键词： Gas-solid flow Circulating fluidized bed EMMS method 3D full-loop simulation

A New Cooperative Distributed MPC Method Based on Reduction and Classification

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2017年第3期26卷 564-572页

作者： WU Lan WANG lei College of Electrical Engineering Henan University of Technology Department of Electrical Engineering Hangzhou First Technician College

To decrease the overlarge calculation induced by the centralized processing,a new cooperative distributed Model predictive control(MPC)method is proposed for large-scale systems with coupled *** and classification are investigated by defining the influence degree to reduce the whole system and then to classify the reduced system into several subsystem *** groups are mutually decoupled,while there is relativity between these subsystems comprised in the same ***/cooperative and distributed MPC algorithms for each group are implemented to ensure the feasibility and the stability of the whole ***,for practical applications,the finite times interactive control strategy between different groups is adopted to compensate information loss brought by the reduced subsystem and realize the global cooperative distributed *** algorithm significantly decreases the computational load,has better control *** are given to illustrate the effectiveness of these developed algorithms.

关键词： Large-scale complex system Reduction and classification Influence degree Cooperative distributed Model predictive control(MPC)

Study on Free-Standing Riser Under Different Working Conditions Based on 3D Co-Rotational Beam Element

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

China Ocean Engineering 2024年第5期38卷 725-738页

作者： HUANG Chen GU Ji-jun JIA Ji-chuan CHEN lei-lei WANG Shu-jiang GAO lei College of Mechanical and Transportation Engineering China University of Petroleum-BeijingBeijing 102200China School of Safety and Engineering Xinjiang Institute of EngineeringUrumqi 830000China CNOOC Research Institute Beijing 100028China

When the free standing riser(FSR)is in service in the ocean,its mechanical properties are affected by various factors,including complex ocean current forces,buoyancy of the buoyancy can,and torque caused by the deflection of the upper floating *** loads have a great influence on the deformation and internal force of the *** static performance of FSR is investigated in this research under various working *** finite element model of FSR is established based on the co-rotational *** arc length approach is used to solve the *** load is exerted in *** current load on the riser changes with the configuration of the *** accuracy of the numerical method is verified by Abaqus *** calculation time is also ***,the effects of uniform current,actual current and floating body yaw motion on FSR are studied by parameter ***,the influence of the FSR on the ocean current after the failure of part of the buoyancy can chamber is *** results show that the numerical model based on the co-rotational method can effectively simulate the large rotation and torsion behavior of *** method has high computational efficiency and precision,and this method can quickly improve the efficiency of numerical calculation of static analysis of deep-water *** proposed technology may serve as an alternative to the existing proprietary commercial software,which uses a complex graphical user interface.

关键词： free standing riser(FSR) co-rotational method finite element method ocean current nonlinear analysis torsion