检索结果-南通市图书馆

Groups with One or Two Super-Brauer Character Theories

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2020年第4期36卷 379-394页

作者： Xiao you chen Mark LLEWIS College of Science Henan University of TechnologyZhengzhou 450001P.R.China Department of Mathematical Sciences Kent State UniversityKent 44242USA

A super-Brauer character theory of a group G and a prime p is a pair consisting of a partition of the irreducible p-Brauer characters and a partition of the p-regular elements of G that satisfy certain *** classify the groups and primes that have exactly one super-Brauer character *** discuss the groups with exactly two super-Brauer character theories.

关键词： Super character theory super-Brauer character theory Brauer characters

Ultraviolet-accelerated formation of bone-like apatite on oxidized Ti-24Nb-4Zr-7.9Sn alloy

在线全文

学校读者我要写书评

暂无评论

Frontiers of Materials Science 2013年第4期7卷 362-369页

作者： Min-Fang chen Jing ZHANG chen you School of Materials Science and Engineering Tianjin University of Technology Tianjin 300384 China Tianjin Key Laboratory for Photoelectric Materials and Devices Tianjin 300384 China

A novel method has been developed to rapidly deposit bone-like apatite with the assistance of ultraviolet （UV） light irradiation on the nanostructured titania in the simulated body fluid （SBF）. The process has three main steps： Ti-24Nb-4Zr-7.9Sn alloy was heated at 650℃ for 3 h, UV-light illumination in air for 4 h and soaking in the SBF for 3 d. A titania coating consisted of main rutile formed on the thermal oxidized Ti-24Nb-4Zr- 7.9Sn alloy. The UV not only converted the futile surface from hydrophilic to hydrophobic but also stimulated high surface activity. After 4 h UV illumination, the contents of Ti3＋ and hydroxyl groups on the oxidized sample were increased, while that of lattice O decreased. After 3 d of soaking in the SBF, a compact and uniform layer of carbonated hydroxyapatite （CHA） particles was formed on the UV-illuminated rutile surface whereas there was a few of HA to be viewed on the surface of as-oxidized Ti-24Nb-4Zr-7.9Sn alloy. Our study demonstrates a simple, fast and cost-effective technique for growing bone-like apatite on titanium alloys.

关键词： Ti-24Nb-4Zr-7.9Sn alloy thermal oxidation UV illumination rutile bone- like apatite

Global Existence and Nonexistence for a Strongly Coupled Parabolic System with Nonlinear Boundary Conditions

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2006年第5期22卷 1297-1304页

作者： you Peng chen Chun Hong XIE Department of Mathematics Nanjing Normal University Nanjing 210097 P. R. China Department of Mathematics Yancheng Normal Institute Yancheng 224002 P. R. China Department of Mathematics Nanjing University Nanjing 210093 P. R. China

This paper deals with the strongly coupled parabolic system ut = v^m△u, vt = u^n△v, （x, t） ∈Ω × （0,T） subject to nonlinear boundary conditions 偏du/偏dη = u^αv^p, 偏du/偏dη= u^qv^β, （x, t） ∈ 偏dΩ × （0, T）, where Ω 包含 RN is a bounded domain, m, n are positive constants and α,β, p, q are nonnegative constants. Global existence and nonexistence of the positive solution of the above problem are studied and a new criterion is established. It is proved that the positive solution of the above problem exists globally if and only if α 〈 1,β 〈 1 and （m ＋p）（n ＋ q） ≤ （1 - α）（1 -β）.

关键词： Strongly coupled Global existence Finite time blow-up Upper and lower solutions

Wigner-Hough transform based on slice's entropy and its application to multi-LFM signal detection

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2017年第4期28卷 634-642页

作者： Hongwei Wang Xiangyu Fan you chen Yuanzhi Yang Aeronautics and Astronautics Engineering College Air Force Engineering University College of Electronic and Information Northwestern Polytechnical University

To enhance the capacity of the radar-reconnaissance interception receiver recognizing linear frequency modulated (LFM) at a low signal-noise ratio, this paper presents WignerHough transform (WHT) of the LFM signal and its corresponding characteristics, derives the probability density functions of the LFM signal and Gaussian white noise within WHT based on entropy (WHTE), dimension under different assumptions and puts forward a WHT algorithm based on entropy of slice to improve the capacity of detecting the LFM signal. Entropy of the WHT domain slice is adopted to assess the information size of polar radius or angle slice, which is converted into the weight factor to weight every slice. Double-deck weight is used to weaken the influences of noise and disturbance terms and WHTE treatment and signal detection procedure are also summarized. The rationality of the algorithm is demonstrated through theoretical analysis and formula derivation, the efficiency of the algorithm is verified by simulation comparison between WHT, fractional Fourier transform and periodic WHT, and it is highlighted that the WHTE algorithm has better detection accuracy and range of application against strong noise background.

关键词： low signal-to-noise ratio linear frequency modulated signal probability density function Wigner-Hough transform (WHT) signal detection entropy of slice

A cooperative interference resource allocation method based on improved firefly algorithm

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2021年第4期17卷 1352-1360页

作者： Huai-xi Xing Hua Wu you chen Kun Wang Aeronautics Engineering College Air Force Engineering UniversityXi’an710038China School of Energy and Power Engineering Shandong UniversityJinan250061China

To deal with the radio frequency threat posed by modern complex radar networks to aircraft,we researched the unmanned aerial vehicle(UAV)formations radar countermeasures,aiming at the solution of radar jamming resource allocation under system countermeasures.A jamming resource allocation method based on an improved firefly algorithm(FA)is ***,the comprehensive factors affecting the level of threat and interference efficiency of radiation source are quantified by a fuzzy comprehensive ***,the interference efficiency matrix and the objective function of the allocation model are determined to establish the interference resource allocation ***,A mutation operator and an adaptive heuristic are integtated into the FA algorithm,which searches an interference resource allocation *** simulation results show that the improved FA algorithm can compensate for the deficiencies of the FA *** improved FA algorithm provides a more scientific and reasonable decision-making plan for aircraft mission allocation and can effectively deal with the battlefield threats of the enemy radar ***,in terms of convergence accuracy and speed as well as algorithm stability,the improved FA algorithm is superior to the simulated annealing algorithm(SA),the niche genetic algorithm(NGA),the improved discrete cuckoo algorithm(IDCS),the mutant firefly algorithm(MFA),the cuckoo search and fireflies algorithm(CSFA),and the best neighbor firefly algorithm(BNFA).

关键词： Radar countermeasure Adaptive heuristics Adversarial effectiveness Fuzzy comprehensive evaluation Mutation operator

Effects of grain size on the corrosion resistance of pure magnesium by cooling rate-controlled solidification

在线全文

学校读者我要写书评

暂无评论

Frontiers of Materials Science 2015年第3期9卷 247-253页

作者： Yichi LIU Debao LIU then you Minfang chen School of Materials Science and Engineering Tianjin University of Technology Tianjin 300384 China

The aim of this study was to investigate the effect of grain size on the corrosion resistance of pure magnesium developed for biomedical applications. High- purity magnesium samples with different grain size were prepared by the cooling rate- controlled solidification, Electrochemical and immersion tests were employed to measure the corrosion resistance of pure magnesium with different grain size. The electrochemical polarization curves indicated that the corrosion susceptibility increased as the grain size decrease. However, the electrochemical impedance spectroscopy （EIS） and immersion tests indicated that the corrosion resistance of pure magnesium is improved as the grain size decreases. The improvement in the corrosion resistance is attributed to refine grain can produce more uniform and density film on the surface of sample.

关键词： pure magnesium solidification cooling rate grain size corrosion resistance

Stirring brazing of dissimilar Al/Mg alloy without flux in air

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2013年第5期32卷 469-474页

作者： Hui-Bin Xu Hui-Bin Sun Hong-you chen School of Materials Science and Engineering Chongqing University of Technology chen State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology

AZ31B magnesium alloy and 2024 aluminum alloy were successfully jointed at aid of mechanical stirring with Sn-Zn-Al filler metal. The microstructure, fracture morphologies, and mechanical properties of joint were investigated. The results show that Mg-Al intermetallic compounds can be avoided by the process. But, a small quantity of porosity is found in the joint. The sheafing strength of joint interface adjacent to magnesium alloy is 35.4 MPa for formation of Mg-Sn intermetallic compounds, which is about 46 % of that of filler metal. While, the shearing strength of joint interfaces adjacent to aluminum alloy is 70.4 MPa for formation of Zn-Sn-Al solid solution, which is about 92 % of that of filler metal.

关键词： 2024 Al alloy AZ31B Mg alloy Stirring brazing

Trapping photons with optical black hole

在线全文

学校读者我要写书评

暂无评论

Light(Science & Applications) 2023年第4期12卷 507-508页

作者： you-Ling chen Qi-Tao Cao Yun-Feng Xiao State Key Laboratory on Integrated Optoelectronics Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Frontiers Science Center for Nano-optoelectronics&School of Physics Peking UniversityBeijing 100871China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006 ShanxiChina

An optical black-hole cavity based on transformation optics enables Q-factor enhancement and strong field confinement,by eliminating the intrinsic radiation loss of the conventional whispering-gallery modes,holding po... 详细信息

关键词： optics eliminating enable

Chiral emission and Purcell enhancement in a hybrid plasmonic-photonic microresonator

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

Light(Science & Applications) 2020年第1期9卷 1961-1962页

作者： Qi-Tao Cao you-Ling chen Yun-Feng Xiao Frontiers Science Center for Nano-optoelectronics&School of Physics Peking UniversityBeijing 100871China State Key Laboratory on Integrated Optoelectronics Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China

A high-Q hybrid plasmonic-photonic microresonator,which consists of a dielectric microdisk hybridized with a plasmonic nanoantenna dimer,enables an enlarged local density of states of the optical field and chiral prop... 详细信息

关键词： cavity plasmon Chiral