检索结果-南通市图书馆

Yield criterions of metal plasticity in different stress states

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2009年第2期22卷 123-130页

作者： Fengping YANG qin sun Wei HU School of Aeronautics Northwestern Polytechnical University Xitan 710072 China Institute of Orthopedic Oncology Tangdu Hospital Fourth Military Medical University Xi＇an 710038 China

Five types of tensile tests were conducted to study the yield .behavior of 2A12-T4 aluminum alloy. Parallel finite element models were built for each test and solved with ABAQUS with different yield criterions. The result shows that any of the four criterions： von Mises yield criterion, Tresca criterion, Twin-Shear criterion and yon Mises criterion with hydrostatic pressure correction, overestimates the yield strengths of the specimens. Rather than hydrostatic pressure, Lode stress parameter is the key factor that affects the differences between experimental and simulation results. Based on this concept, a new yield model with Lode dependence modified from yon Mises criterion is postulated. Although one more parameter needs to be confirmed, the simulation results of this yield model are better than those of other criterions.

关键词： Yield strength Lode stress parameter Hydrostatic pressure Finite element method (FEM)

Synthesis of Polybutadienes with Controllable Microstructure by a Novel Binary Nd(3-NBSO_3)_3/Alkylaluminum Catalyst System

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2015年第3期33卷 475-480页

作者： Ji-qin Wen xue-quan Zhang 代全权 Key Laboratory of Synthetic Rubber Changchun Institute of Applied ChemistryChinese Academy of Sciences Jiangsu Province Institute for Medical Equipment Testing

The polymerization of 1,3-butadiene was examined by using a novel halogen-free neodymium m-nitrobenzenesulfonate （Nd（3-NBSOa）3·donors）/alkylaluminum binary catalyst system. The catalyst showed fairly high activity and controllable selectivity. The microstructure of the resultant polymer was adjustable by variation of electron donor and/or the alkylaluminum. ^13C-NMR and thermal analysis demonstrate that the produced polybutadienes have stereo-block chain structures of cis-1,4 and trans-1,4 segments with adjustable Tm and To. The neodymium sulfonate-based catalyst is believed to be significant in regulating the chain structure of polydienes and in exploring 1,3-diene polymerization mechanism.

关键词： Polybutadiene Microstructure Ziegler-Natta polymerization.

Integrated Control Strategy for CVT Powertrains with Consideration of Vehicle Drivability

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2012年第3期25卷 515-523页

作者： sun Dongye LUO Yong qin Datong State Key Laboratory of Mechanical Transmission Chongqing UniversityChongqing 400044China

During shift,power flow is not interrupted in powertrains equipped with continuously variable transmission（CVT）.When hard acceleration is commanded,engine speed will flare and corresponding torque will be consumed,which leads to a drop in vehicle drive torque and also the vehicle *** is the reason why CVT vehicles have poor drivability during hard acceleration *** method such as torque compensation doesn＇t always work due to the limited backup torque of *** to this,means to evaluate the drivability of CVT vehicles are studied,affect factors of drivability are analyzed in *** acceleration process of CVT vehicle is studied by theoretical analysis,based on which engine torque and ratio change rate of CVT are identified as two key control parameters that decide the drivability of CVT vehicles during hard acceleration ***,a control strategy based on restricting the change rate of CVT ratio together with torque compensation is proposed,and two different algorithms to establish the limitation of ratio change rate are *** two algorithms are simulated and compared with each other,results indicate that drop of vehicle acceleration is eliminated evidently by limit the change rate of CVT ratio,but small ratio change rate also results in a longer time to finish the accelerate process,an algorithm to decide a proper ratio change rate is needed in order to tune these different *** order to get better control effects,a new fuzzy logic based algorithm is proposed to decide a proper ratio change rate during kick down conditions,simulation and experiment results indicate that,the amount of vehicle acceleration decrease is reduced from about 1 m/s2 to almost 0,in the mean time the accelerate process only delayed for about 0.3 *** proposed control strategy and algorithm can effectively tune the characteristics of CVT equipped vehicle during kick down conditions.

关键词： vehicles continuously variable transmission control strategy drivability

MPFracNet:A Deep Learning Algorithm for Metacarpophalangeal Fracture Detection with Varied Difficulties

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2023年第4期75卷 999-1015页

作者： Geng qin Ping Luo Kaiyuan Li Yufeng sun Shiwei Wang Xiaoting Li Shuang Liu Linyan xue College of Quality and Technical Supervision Hebei UniversityBaoding071002China Hebei Technology Innovation Center for Lightweight of New Energy Vehicle Power System Baoding071002China National&Local Joint Engineering Research Center of Metrology Instrument and System Hebei UniversityBaoding071002China

Due to small size and high occult,metacarpophalangeal fracturediagnosis displays a low accuracy in terms of fracture detection and locationin X-ray *** efficiently detect metacarpophalangeal fractures on Xrayimages as the second opinion for radiologists,we proposed a novel onestageneural network namedMPFracNet based ***,a deformable bottleneck block(DBB)was integrated into the bottleneckto better adapt to the geometric variation of the ***,an integrated feature fusion module(IFFM)was employed to obtain morein-depth semantic and shallow detail ***,Focal Loss andBalanced L1 Loss were introduced to respectively attenuate the imbalancebetween positive and negative classes and the imbalance between detectionand location *** assessed the proposed model on the test set andachieved an AP of 80.4%for the metacarpophalangeal fracture *** estimate the detection performance for fractures with different difficulties,the proposed model was tested on the subsets of metacarpal,phalangeal andtiny fracture test sets and achieved APs of 82.7%,78.5%and 74.9%,*** proposed framework has state-of-the-art performance for detectingmetacarpophalangeal fractures,which has a strong potential application valuein practical clinical environments.

关键词： Deep learning small object detection metacarpophalangeal fractures computer-aided diagnosis(CAD)

General semi-analytical solutions to one-dimensional consolidation for unsaturated soils

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

Applied Mathematics and Mechanics(English Edition) 2017年第6期38卷 831-850页

作者： Lei WANG De'an sun Aifang qin Department of Civil Engineering Shanghai University

This paper presents general semi-analytical solutions to Fredlund and Hasan＇s one-dimensional （1D） consolidation equations for unsaturated soils subject to different initial conditions, homogeneous boundaries and time-dependent loadings. Two variables are introduced to transform the two-coupled governing equations of pore-water and poreair pressures into an equivalent set of partial differential equations （PDEs）, which are solved with the Laplace transform method. The pore-water and pore-air pressures and settlement are obtained in the Laplace transform domMn. The Crump＇s method is used to perform inverse Laplace transform to obtain the solutions in the time domain. The present solutions are more general in practical applications and show good agreement with the previous solutions in the literature.

关键词： semi-analytical solution unsaturated soil one-dimensional consolidation,homogeneous boundary condition time-dependent loading

Accuracy improvement of GPS/MEMS-INS integrated navigation system during GPS signal outage for land vehicle navigation

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2012年第2期23卷 256-264页

作者： Honglei qin Li Cong Xingli sun School of Electronics and Information Engineering Beihang UniversityBeijing 100191P.R.China

To improve the reliability and accuracy of the global po- sitioning system （GPS）/micro electromechanical system （MEMS）- inertial navigation system （INS） integrated navigation system, this paper proposes two different methods. Based on wavelet threshold denoising and functional coefficient autoregressive （FAR） model- ing, a combined data processing method is presented for MEMS inertial sensor, and GPS attitude information is also introduced to improve the estimation accuracy of MEMS inertial sensor errors. Then the positioning accuracy during GPS signal short outage is enhanced. To improve the positioning accuracy when a GPS signal is blocked for long time and solve the problem of the tra- ditional adaptive neuro-fuzzy inference system （ANFIS） method with poor dynamic adaptation and large calculation amount, a self-constructive ANFIS （SCANFIS） combined with the extended Kalman filter （EKF） is proposed for MEMS-INS errors modeling and predicting. Experimental road test results validate the effi- ciency of the proposed methods.

关键词： functional coefficient autoregressive (FAR) global po- sitioning system (GPS) micro electromechanical system (MEMS) inertial navigation system (INS) self-constructive adaptive neuro- fuzzy inference system (SCANFIS).

Searching for novel materials via 4f chemistry

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2019年第1期37卷 1-10,M0002页

作者： Congting sun Keyan Li Dongfeng xue State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied ChemistryChinese Academy of Sciences State Key Laboratory of Fine Chemicals PSU-DUT Joint Center for Energy ResearchSchool of Chemical EngineeringDalian University of Technology

4f chemistry studies the chemical bonding characteristics of fifteen lanthanide (Ln) elements in the periodic table and their wide applications in materials sciences and engineering, which forms the scientific fundamentals ofⅥperiodic elements in the periodic table of elements. Orbital hybridization modes of Ln elements clarify their chemical bonding nature in all reaction systems. Wide coordination number (CN) option, ranging from 2 to 16, is the reason why Ln elements are the treasure of new materials, therefore, searching for novel materials may be well carried out via the rational design of coordination environment of central Ln cations to stabilize their variable energy states. Balance utilization of Ln elements is dependent on their coordination architecture in the crystallographic frame, Ln elements can be replaced by non-Ln elements when CN <10, and when CN≥10 expensive Ln elements can be replaced by those cheaper ones.

关键词： 4f chemistry Chemical bonding Electronegativity Orbital hybridization Novel structure Balance utilization of lanthanide elements

Leveraged fault identification method for receiver autonomous integrity monitoring

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2015年第4期28卷 1217-1225页

作者： sun Yuan Zhang Jun xue Rui School of Electronic and Information Engineering Beihang University

Receiver autonomous integrity monitoring（RAIM） provides integrity monitoring of global positioning system（GPS） for safety-of-life *** the process of RAIM, fault identification（FI） enables navigation to continue in the presence of fault *** by satellite geometry, the leverage of each measurement in position solution may differ ***, the conventional RAIM FI methods are generally based on maximum likelihood of ranging error for different measurements, thereby causing a major decrease in the probability of correct identification for the fault measurement with high *** this paper, the impact of leverage on the fault identification is *** leveraged RAIM fault identification（L-RAIM FI） method is proposed with consideration of the difference in leverage for each satellite in ***,the theoretical probability of correct identification is derived to evaluate the performance of L-RAIM FI *** experiments in various typical scenarios demonstrate the effectiveness of L-RAIM FI method over conventional FI methods in the probability of correct identification for the fault with high leverage.

关键词： Fault identification Global positioning system Leverage Navigation systems Receiver autonomousintegrity monitoring

Improved iterative convergence method in Q-ary LDPC coded high order PR-CPM

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2016年第3期27卷 541-548页

作者： Danfeng Zhao Yanbo sun Rui xue College of Information and Communication Engineering Harbin Engineering University

The Q-ary low-density parity-check（LDPC） coded high order partial response continuous phase modulation（PR-CPM） with double iterative loops is investigated. This scheme shows significant improvements in power and bandwidth efficiency, but at the expense of long iterative decoding delay and computational complexity induced by the improper match between the demodulator and the decoder. To address this issue, the convergence behavior of Q-ary LDPC coded CPM is investigated for the Q=2 and Q〉2 cases, and an optimized design method based on the extrinsic information transfer chart is proposed to improve the systematic iterative efficiency. Simulation results demonstrate that the proposed method can achieve a perfect tradeoff between iterative decoding delay and bit error rate performance to satisfy real-time applications.

关键词： iterative detection convergence low-density paritycheck(LDPC) code continuous phase modulation(CPM) extrinsic information transfer chart