检索结果-南通市图书馆

Beam resource scheduling for a VHF-MIMO radar network in low-angle tracking

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 Aeronautics 2023年第4期36卷 423-441页

作者： Haowei zhang Weijian LIU Taiyong fei Air and Missile Defense College Air Force Engineering UniversityXi’an 710051China Air Force Early Warning Academy Wuhan 410039China

The low-angle tracking in multipath interference is a challenging problem for the Very High Frequency(VHF)*** colocated Multi-Input Multi-Output(MIMO)technique can remedy such a *** this paper,a Joint Beam-Target Assignment and Power Allocation(JBTAPA)strategy is proposed for the VHF-MIMO radar network tracking low-angle *** core of the JBTAPA strategy is to improve the worst tracking accuracy among multiple targets by assigning appropriate beams to targets and allocating the power resource in each beam using the feedback information in the tracking *** into account the transmit multipath and receive multipath,we derive the Cramer-Rao Lower Bound(CRLB)on angle estimate,which is then incor-porated in the Predicted Conditional CRLB(PC-CRLB).A more accurate and consistent lower bound is provided as the optimization metric since the PC-CRLB is based on the most recently real-ized measurements.A two-stage-based technique is proposed to solve the JBTAPA problem,which is originally *** results verify the effectiveness and efficiency of the proposed *** results also imply that the target reflectivity plays one of the important roles in resource allocation.

关键词： Convex optimization Low-angle tracking MIMO radar PC-CRLB Resource allocation

Simulation of gas-solid adsorption process considering particle-size distribution

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2023年第2期54卷 331-342页

作者： Jihui Li Bingjian zhang Yidan shu School of Materials Science and Engineering Sun Yat-sen UniversityGuangzhou 510006China

The particle-size distribution of adsorbents usually plays an important role on the adsorption performance. In this study, population balance equation(PBE) is utilized in the simulation of an adsorption process to model the time-dependent adsorption amount distribution on adsorbent particles of a certain size distribution. Different adsorption kinetics model can be used to build the adsorption rate function in PBE according to specific adsorption processes. Two adsorption processes, including formaldehyde on activated carbon and CO_(2)/N_(2)/CH_(4) mixture on 4A zeolite are simulated as case studies, and the effect of particle-size distribution of adsorbent is analyzed. The simulation results proved that the influence of particle-size distribution is significant. The proposed model can help consider the influence of particlesize distribution of adsorbents on adsorption processes to improve the prediction accuracy of the performance of adsorbents.

关键词： Adsorption Population balance equations Particle-size distribution

Giant magneto-impedance effect of two paralleled amorphous microwires

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2016年第4期35卷 344-348页

作者： shu-Ling zhang Yue-Sheng Chai Da-Qing Fang Lu-Cai Wang Da-Wei Xing Jian-fei Sun School of Materials Science and Engineering Taiyuan University of Science and Technology School of Materials Science and Engineering Harbin Institute of Technology

Giant magneto-impedance （GMI） is effectively enhanced by the mutual magnetic interaction between two amorphous microwires. A comparative study on GMI properties of a single wire and two wires arranged in par- allel mode was reported in this work. Two-peak （TP） of impedance characteristic is presented when the dc external field changed from 0 to 320 A,m-＇ in two-wire system, which is attributed to successive magnetization process in two wires induced by their magnetic interaction. And the evolution of single peak to TP phenomenon, when the distance between two wires is upto 8 ram, evidences a distance dependence of transformation from successive magnetization to simultaneous via a corresponding dis- tance dependence of magnetostatic interactions. It is pro- posed that the recombination of magnetic interaction and the shielding effect results in a distance dependency of GMI response. When the distance is 8 ram, the magneti- zation process is close to synchronous between two wires, which give rises to higher circular permeability and better GMI response. The impedance ratio AZ/Z increases from 74.5 % of single wire to 172.4 % at 10 MHz. However, when the distance is upto 12 mm, the magnetic interaction is weak and magnetization process is completely independent, and GMI response decreases, relatively. This indicates that the GMI response could be effectively improved in a two-wire connection with an optical distance, which is promising and useful for the application of high-performance GMI sensors.

关键词： Amorphous microwire Magnetic interaction Giant magneto-impedance Magnetization

Random Neighbor Sandpile Model with Constrained Total Energy

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2000年第1期17卷 37-39页

作者： zhang shu-Dong Institute of Low Energy Nuclear Physics Beijing Normal UniversityBeijing 100875

We propose an energy-constrained sandpile model with random *** critical behavior of the model is in the same universality class as the mean-field self-organized criticality *** critical energy Ec depends on the number of neighbors n of each site,but the various exponents do *** n=6,we got that Ec=0.4545;and a sei匸similar structure of the energy distribution function with five major peaks is also *** is a natural result of system dynamics and the way the system is disturbed.

关键词： system neighbor critical

Microstructure and mechanical properties of high-strength high-pressure die-cast Mg–4Al–3La–1Ca–0.3Mn alloy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2021年第10期40卷 2956-2963页

作者： Peng-fei Qin Qiang Yang Yu-Ying He Jing-Huai zhang Jin-shu Xie Xi-Ru Hua Kai Guan Jian Meng Key Laboratory of Superlight Materials and Surface Technology Ministry of EducationHarbin Engineering UniversityHarbin 150001China State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China Department of Materials Science and Engineering University of TokyoTokyo 113-8654Japan

A new high-pressure die-cast(HPDC) Mg–4 Al–3 La–1 Ca–0.3 Mn(ALaX431) alloy with high strength has successfully been fabricated. This HPDC alloy in peakaged state exhibits tensile yield strength(TYS) of 220 MPa at room temperature and TYS of 145 MPa at 250 ℃,higher than the corresponding strength of HPDC Mg alloys reported so far. These high strengths are mainly due to the formation of fine grained structure, semi-continuous reticular structure consisting of stable Al_(3)La and(Mg,Al)2 Ca particles along grain boundaries and numerous nanoscale Al_(2)Ca precipitates within grains. Due to its higher strength than existing HPDC Mg alloys, the new developed alloy has great application potential.

关键词： Magnesium alloys High-pressure die-cast Mechanical property Intermetallic phase

A Survey of Text Summarization Approaches Based on Deep Learning

在线全文

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2021年第3期36卷 633-663页

作者： Sheng-Luan Hou Xi-Kun Huang Chao-Qun fei shu-Han zhang Yang-Yang Li Qi-Lin Sun Chuan-Qing Wang Institute of Computing Technology Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Academy of Mathematics and Systems Sciences Chinese Academy of SciencesBeijing 100190China Key Laboratory of Management Decision and Information SystemChinese Academy of SciencesBeijing 100190China

Automatic text summarization(ATS)has achieved impressive performance thanks to recent advances in deep learning(DL)and the availability of large-scale *** key points in ATS are to estimate the salience of information and to generate coherent ***,a variety of DL-based approaches have been developed for better considering these two ***,there is still a lack of comprehensive literature review for DL-based ATS *** aim of this paper is to comprehensively review significant DL-based approaches that have been proposed in the literature with respect to the notion of generic ATS tasks and provide a walk-through of their *** first give an overview of ATS and *** comparisons of the datasets are also given,which are commonly used for model training,validation,and *** we summarize single-document summarization *** that,an overview of multi-document summarization approaches is *** further analyze the performance of the popular ATS models on common *** popular approaches can be employed for different ATS ***,we propose potential research directions in this fast-growing *** hope this exploration can provide new insights into future research of DL-based ATS.

关键词： automatic text summarization artificial intelligence deep learning attentional encoder-decoder natural language processing

OPTIMAL QUADRATIC NITSCHE EXTENDED FINITE ELEMENT METHOD FOR INTERFACE PROBLEM OF DIFFUSION EQUATION

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2018年第5期36卷 693-717页

作者： fei Wang shuo zhang School of Mathematics and Statistics Xi'an Jiaotong University Xi'an 710049 China Department of Mathematics Pennsylvania State University University Park PA 16802 USA. LSEC ICMSEC NCMIS Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing 100190 China.

In this paper, we study Nitsche extended finite element method （XFEM） for the inter- face problem of a two dimensional diffusion equation. Specifically, we study the quadratic XFEM scheme on some shape-regular family of grids and prove the optimal convergence rate of the scheme with respect to the mesh size. Main efforts are devoted onto classifying the cases of intersection between the elements and the interface and prove a weighted trace inequality for the extended finite element functions needed, and the general framework of analysing XFEM c^n be implemented then.

关键词： Interface problems Extended finite element methods Error estimates Nitsche's scheme Quadratic element.

Advances in single-particle detection for DNA sensing

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 2017年第10期60卷 1285-1292页

作者： fei Ma Ming Ren Chun-yang zhang College of Chemistry Chemical Engineering and Materials Science Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of ShandongKey Laboratory of Molecular and Nano Probes Ministry of Education Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals Shandong Normal University Jinan 250014 China

Rapid, accurate and sensitive detection of particular DNA sequence is critical in fundamental biomedical research and clinical diagnostics. However, conventional approaches for DNA assay often suffer from cumbersome procedures, long analysis time and insufficient sensitivity. Recently, single-particle detection technology has emerged as a powerful tool in the biosensing area due to its significant advantages of ultrahigh sensitivity, low sample-consumption and rapid analysis time. Especially, the introduction of novel nanomaterials has greatly promoted the development of single-particle detection and its applications for DNA sensing. In this review, we summarize the recent advance in single-particle detection strategies for DNA sensing, and focus mainly on metallic nanoparticle-and semiconductor quantum dot-based single-particle detection. We highlight the emerging trends in this field as well.

关键词： single-particle detection DNA assay quantum dots metallic nanoparticles fluorescence resonance energy transfer

Homogeneity-preserving property of harmonic sequences from surfaces into complex Grassmann manifolds

在线全文

学校读者我要写书评

暂无评论

Frontiers of Mathematics in China 2017年第5期12卷 1131-1137页

作者： Jie fei Wenjuan zhang Department of Mathematical Sciences Xi'an Jiaotong-Liverpool UniversitySuzhou 215123 China School of Science East China University of Technology Nanchang 330013 China

We prove that if φ is a homogeneous harmonic map from a Riemann surface M into a complex Grassmann manifold G（k, n）, then the maps of the harmonic sequences generated by φ are all homogeneous.

关键词： Complex Grassmann manifold harmonic sequence homogeneoussurface