检索结果-南通市图书馆

INVARIANT DENSITY, LYAPUNOV EXPONENT, AND ALMOST SURE STABILITY OF MARKOVIAN-REGIME-SWITCHING LINEAR SYSTEMS

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2011年第1期24卷 79-92页

作者： Qi he gang George YIN Department of Mathematics Wayne State University Detroit MI 48202 USA

This paper is concerned with stability of a class of randomly switched systems of ordinary differential equations. The system under consideration can be viewed as a two-component process （X（t）, α（t））, where the system is linear in X（t） and α（t） is a continuous-time Markov chain with a finite state space. Conditions for almost surely exponential stability and instability are obtained. The conditions are based on the Lyapunov exponent, which in turn, depends on the associate invaxiant density. Concentrating on the case that the continuous component is two dimensional, using transformation techniques, differential equations satisfied by the invariant density associated with the Lyapunov exponent are derived. Conditions for existence and uniqueness of solutions are derived. Then numerical solutions are developed to solve the associated differential equations.

关键词： Invariant density Lyapunov exponent randomly switching ordinary differential equation.

PandaX-I result sets a stringent limit for low-mass dark matter particles

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

National Science Review 2015年第2期2卷 128-129页

作者： Xiao-gang he Department of Physics and Astronomy Shanghai Jiao Tong University

Astrophysical and cosmological observations show that about 27%of the energy in our universe comes from dark mater(DM).What is DM is an outstanding puzzle in science in the 21st *** weakly interacting massive particle... 详细信息

关键词： WIMP PandaX-I result sets a stringent limit for low-mass dark matter particles than

Dimensional Results for Cartesian Products of Homogeneous Moran Sets

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2012年第4期28卷 673-680页

作者： Li CAO Xing-gang he School of Mathematics and Statistics Wuhan University College of Mathematics and Statistics Central China Normal University

M（J, {ms ＊ ns}, {Cs}） be the collection of Cartesian products of two homogenous Moran sets with the same ratios {cs} Where J = [0, 1] × [0, 1]. Then the maximal and minimal values of the Hausdorff dimensions for t... 详细信息

关键词： Homogeneous Moran sets Cartesian product Hausdorff dimension

Synthesis of β-alkynyl α-amino acids via palladium-catalyzed alkynylation of unactivated C(sp^3)-H bonds

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2015年第8期58卷 1345-1348页

作者： Bo Wang gang he Gong Chen Department of Chemistry the Pennsylvania State University University Park

β-Di-substituted α-amino acids(AAs) contain adjacent carbon stereogenic centers and pose considerable synthetic challenge. Complementary to the conventional synthesis strategies based on the transformation of existing functional groups, we envisioned these molecules could be quickly accessed via selective functionalization of sp3 hybridized C-H bonds on the side chains of common α-AA precursors. We report a readily applicable method to prepare β-alkynyl α-amino acids via Pd-catalyzed diastereoselective C(sp3)-H alkynylation of common α-amino acids precursors with acetylene bromide.

关键词： α-amino acids C-H functionalization palladium

Numerical study of thermal history in laser aided direct metal deposition process

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2012年第8期55卷 1431-1438页

作者： ZHANG YongJie YU gang he XiuLi Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China

Temperature evolution in the laser aided direct metal deposition (LADMD) process has considerable influence on the micro-structure and properties of the final part. A 3D transient finite element model was developed to study the temperature evolution during the multilayer LADMD process. To make the property analysis from thermal history easier, a critical temperature specific to thermal history was defined and the distribution of it in the part was also discussed. The simulation results indicated that the critical temperature can make the property analysis from thermal history easier. Thermal history of all the deposited materials was similar. It was also concluded that process parameters needed to be time-varying according to the real-time temperature field during the process.

关键词： laser-aided direct metal deposition finite element modeling thermal history

Water as dispersion medium to fabricate homogeneous nanohectorite solid-state electrolyte for suppressing lithium dendrite

在线全文

学校读者我要写书评

暂无评论

Journal of Materiomics 2024年第2期10卷 463-470页

作者： Xin Pei Wenfei Wei gang he Xinjiang Institute of Technology Xinjiang843100China Engineering Research Center of Nano-Geomaterials of Ministry of Education Faculty of Materials Science and ChemistryChina University of GeosciencesWuhan430074China Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources Qinghai Institute of Salt LakesChinese Academy of SciencesXiningQinghai810008China

The rational design of green chemical,low-cost,and highly efficient solid-state electrolytes for Li-metal anode is a promising but still challenging strategy for preventing Li dendrite growth and developing safe and ultralong cycle life Li-metal ***,a homogeneous composite solid polymer electrolyte(CSPE)is fabricated with water as the ideal dispersion medium,hectorite(Ht)as nanofiller,and poly(ethylene oxide)(PEO)as the matrix,to guide uniform Li plating/*** from the merit of Ht can form uniformly dispersed nanosheets in water,the obtained CSPE inheres to a low melting point,robust mechanical property,and high Li^(+)transference ***,the fabricated Li symmetric battery using PEO-Ht-LiClO_(4)CSPE keeps cycling steadily for 4000 *** well demonstrated water-based CSPE paves the way for developing low-cost,environmentally friendly,and safe solid-state electrolytes for Li-metal batteries.

关键词： Water Solid-state electrolytes Homogeneous hectorite Li-metal battery

Atomic-layer-deposited （ALD） Al2O3passivation dependent interface chemistry, band alignment and electrical properties of HfYO/Si gate stacks

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

Journal of Materials Science & Technology 2019年第5期35卷 769-776页

作者： Shuang Liang gang he Die Wang Fen Qiao School of Physics and Materials Science Radiation Detection Materials & Devices Lab Anhui UniversityHefei 230601 China Institute of Physical Science and Information Technology Anhui University Hefei 230601 China School of Energy & Power Engineering Jiangsu University Zhenjiang 212013 China

In this work, the effects of atomic-layer-deposited(ALD) Al2O3 passivation layers with different thicknesses on the interface chemistry and electrical properties of sputtering-derived HfYO gate dielectrics on Si substrates have been investigated. The results of electrical measurements and X-ray photoelectron sepectroscopy(XPS) showed that 1-nm-thick Al2O3 passivation layer is optimized to obtain excellent electrical and interfacial properties for HfYO/Si gate stack. Then, the metal-oxide-semiconductor capacitors with HfYO/1-nm Al2O3/Si/Al gate stack were fabricated and annealed at different temperatures in forming gas(95% N2+5% H2). Capacitance-voltage(C-V) and current density-voltage(J-V) characteristics showed that the 250℃-annealed HYO high-k gate dielectric thin film demonstrated the lowest border trapped oxide charge density(-3.3 × 1010 cm-2), smallest gate-leakage current(2.45 × 10-6 A/cm2 at 2 V)compared with other samples. Moreover, the annealing temperature dependent leakage current conduction mechanism for Al/HfYO/Al2O3/Si/Al MOS capacitor has been investigated systematically. Detailed electrical measurements reveal that Poole-Frenkle emission is the main dominant emission in the region of low and medium electric fields while direct tunneling is dominant conduction mechanism at high electric fields.

关键词： Al2O3passivation layer Co-sputtering HYO films Annealing Electrical properties Conduction mechanism

Flavor SU(3)topological diagram and irreducible representation amplitudes for heavy meson charmless hadronic decays:mismatch and equivalence

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2018年第10期42卷 59-68页

作者： Xiao-gang he Wei Wang T.-D.Lee Institute and INPAC Shanghai Key Laboratory for Particle Physics and CosmologyMOE Key Laboratory for Particle PhysicsSchool of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240 Department of Physics National Taiwan UniversityTaipei 106 National Center for Theoretical Sciences TsingHua UniversityHsinchu 300

Flavor SU（3） analysis of B meson charmless hadronic two light pseudoscalar decays can be formulated in two different ways. One is to construct the SU（3） irreducible representation amplitude （IRA） according to effective Hamiltonian transformation properties, and the other is to draw the topological diagrams （TDA）. We first point out that previous analyses of TDA and IRA approaches do not match in several aspects, in particular a few SU（3） independent amplitudes have been overlooked in the TDA approach. This has caused confusions in the past and sometimes resulted in incorrect interpretation of data. We then demonstrate that only if these amplitudes are included, a consistent and unified picture can be obtained. With the new TDA amplitudes, all charmless hadronic decays of heavy meson must have nonzero direct CP symmetries as already predicted by the IRA approach. In addition to their notable impact on CP asymmetry, the new amplitudes are also important to extract new physics information.

关键词： heavy flavor physics flavor SU(3) symmetry topological diagrams

Synthesis of non-classical heteroaryl C-glycosides via Minisci-type alkylation of N‑heteroarenes with 4-glycosyl-dihydropyridines

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2020年第11期63卷 1613-1618页

作者： Qingbing Wang Juan Duan Pingping Tang Gong Chen gang he State Key Laboratory and Institute of Elemento-Organic Chemistry College of ChemistryNankai UniversityTianjin 300071China

A radical-mediated method was reported for diastereoselective synthesis of non-classical heteroaryl C-glycosides via Minisci-type alkylation of N-heteroarenes with 4-glycosyl-1,4-dihydropyridine(DHP)*** DHP reagents serve as convenient precursors for various glycosyl radicals under the activation of single electron transfer(SET)oxidation by persulfate and visible light irradiation with or without photocatalyst.

关键词： non-classical C-glycoside Minisci reaction 4-gIycosyl-dihydropyridine