检索结果-南通市图书馆

Density Results for Subspace Multiwindow Gabor Systems in the Rational Case

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

Acta Mathematica Sinica,English Series 2013年第5期29卷 897-912页

作者： Qiao fang lian Hai Li MA Department of Mathematics Beijing Jiaotong University

Let S be a periodic set in R and L2（S） be a subspace of L2（R）. This paper investigates the density problem for multiwindow Gabor systems in L2（S） for the case that the product of time- frequency shift parameters is a rational number. We derive the density conditions for a multiwindow Gabor system to be complete （a frame） in L2（S）. Under such conditions, we construct a multiwindow tight Gabor frame for L2 （S） with window functions being characteristic functions. We also provide a characterization of a multiwindow Gabor frame to be a Riesz basis for L2（S）, and obtain the density condition for a multiwindow Gabor Riesz basis for L2 （S）.

关键词： Multiwindow Gabor frames Riesz bases subspaces Zak transform density conditions

The Spectrum Sequences of Periodic Frame Multiresolution Analysis

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2009年第3期25卷 403-418页

作者： Yun Zhang LI Qiao fang lian College of Applied Sciences Beijing University of Technology Beijing 100124 P. R. China Department of Mathematics Beijing Jiaotong University Beijing 100044 P. R. China

The periodic multiresolution analysis （PMRA） and the periodic frame multiresolution analysis （PFMRA） provide a general recipe for the construction of periodic wavelets and periodic wavelet frames, respectively. This paper addresses PFMRAs by the introduction of the notion of spectrum sequence. In terms of spectrum sequences, the scaling function sequences generating a normalized PFMRA are characterized; a characterization of the spectrum sequences of PFMRAs is obtained, which provides a method to construct PFMRAs since its proof is constructive; a necessary and sufficient condition for a PFMRA to admit a single wavelet frame sequence is obtained; a necessary and sufficient condition for a PFMRA to be contained in a given PMRA is also obtained. What is more, it is proved that an arbitrary PFMRA must be contained in some PMRA. In the meanwhile, some examples are provided to illustrate the general theory.

关键词： PFMRA periodic wavelet frame scaling function sequence spectrum spectrum sequence

The sulfolane-based liquid electrolyte with LiClO_(4)additive for the wide-temperature operating high nickel ternary cathode

在线全文

学校读者我要写书评

暂无评论

Nano Research 2023年第3期16卷 3855-3863页

作者： Yixin Zhu Shuang He Jiayi Ding Guangyu Zhao fang lian School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China University of New South Wales PontypriddCF371DLUK

An adequate wide temperature electrolyte for high nickel ternary cathode is urgent to further develop high energy density ***,a comprehensive double-salt local high-concentration sulfolane-based electrolyte(DLi)is proposed with specific sheath structure to build stable interface on the LiNi_(0.8)Co_(0.1)Mn_(0.1O2)(NCM811)cathode at wide operating temperature between−60 and 55℃.Lithium perchlorate(LiClO_(4))in combination with high concentration lithium bis-(trifluoromethanesulfonyl)imide(LiTFSI)strengthens the internal interaction between anion and cation in the solvation structure,increasing Li+transference number of the electrolyte to ***,the structure and component characteristics of the passive interface layer on NCM811 are modulated,decreasing desolvation energy of Li+ions,benefiting Li+transport dynamics especially at low temperature,and also ensuring the interfacial stability at a wide operating temperature *** a result,the cathode with DLi exhibits excellent high-temperature storage performance and high capacity retention of 80.5%in 100 cycles at 55℃.Meanwhile,the Li||NCM811 cells can deliver high discharge capacity of 160.1,136.1,and 110.3 mAh·g^(−1)under current density of 0.1 C at−20,−40,and−60℃,maintaining 84.5%,71.8%,and 58.2%of the discharge capacity at 30℃,***,it enables NCM811 cathode to achieve a reversible capacity of 142.8 mAh·g^(−1)in 200 cycles at−20℃and 0.2 *** studies shed light on the molecular strategy of wide operational temperature electrolyte for high nickel ternary cathode.

关键词： liquid electrolyte high nickel ternary cathode wide temperature interface sheath structure

Reaction mechanisms for 0.5Li_2MnO_3 ·0.5LiMn_(0.5)Ni_(0.5)O_2 precursor prepared by low-heating solid state reaction

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

International Journal of Minerals,Metallurgy and Materials 2012年第9期19卷 856-862页

作者： Dong Li fang lian Xin-mei Hou Kuo-chih Chou School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Department of Physical Chemisitry University of Science and Technology Beijing Beijing 100083 China

Lithium-excess manganese layered oxides, which are commonly described in chemical formula 0.5Li2MnO3·0.5LiMn0.5Ni0.5O2, were prepared by low-heating solid state reaction. The reaction mechanisms of synthesizing precursors, the decomposition mechanism, and intermediate materials in calcination were investigated by means of Fourier transform infrared spectroscopy （FT-IR）, X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM）, thermogravimetric analysis （TGA）, and differential scanning calorimetry （DSC）. The major diffraction patterns of 0.5Li2MnO3·0.5LiMn0.5Ni0.5O2 powder calcinated at 720℃ for 15 h are indexed to the hexagonal structure with a space group of R3m, and the clear splits of doublets at （006）/（102） and （108）/（110） indicate that the sample adopts a well-layered structure. FESEM images show that the size of the agglomerated particles of the sample ranges from 100 to 300 nm.

关键词： lithium batteries electrode manganese oxide solid state reactions calcination

Revisiting Probabilistic Teleportation Scheme for Atomic State via Cavity QED

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2006年第2X期46卷 217-220页

作者： HAN lian-fang fang Ming SHI Shou-Hua ZHANG Zhan-Jun School of Physics and Material Science Anhui University Hefei 230039 China

A probabilistic teleportation scheme for atomic stats via cavity QED [Phys. Rev. A 70 （2004） 054303] is revisited and accordingly some improvements are made.

关键词： probabilistic teleportation cavity QED atomic state

Deterministic Quantum Secure Direct Communication with Dense Coding and Continuous Variable Operations

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2009年第4期51卷 648-652页

作者： HAN lian-fang CHEN Yue-Ming YUAN Hao Teaching and Research Section of Physics School of Basic Medical Science Anhui Medical University Hefei 230032 China Department of Mathematics and Physics West Anhui University Lu＇an 237012 China

We propose a deterministic quantum secure direct two check photon sequences are used to check the securities of the communication protocol by using dense coding. The channels between the message sender and the receiver. The continuous variable operations instead of the usual discrete unitary operations are performed on the travel photons so that the security of the present protocol can be enhanced. Therefore some specific attacks such as denial-of-service attack, intercept-measure-resend attack and invisible photon attack can be prevented in ideal quantum channel. In addition, the scheme is still secure in noise channel. Furthurmore, this protocol has the advantage of high capacity and can be realized in the experiment.

关键词： ping-pong protocol continuous variable operations quantum secure direct communication security capacity

Optimized Local Trigonometric Bases with Nonuniform Partitions

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4期22卷 1069-1084页

作者： Qiao fang lian Yong Ge WANG Dun Yan YAN Department of Mathematics Beijing Jiaotong University Beijing 100044 P. R. China Department of Applied Mathematics Beijing University of Aeronautics and AstronauticsBeijing 100083 P. R. China Institute of Mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 P. R. China School of Information Science and Engineering the Graduate School of the Chinese Academy of Sciences Beijing 100039 P. R. China

The authors provide optimized local trigonometric bases with nonuniform partitions which efficiently compress trigonometric functions. Numerical examples demonstrate that in many cases the proposed bases provide bette... 详细信息

关键词： Optimized local trigonometric bases Bell functions Nonuniform partitions

Synthesis and characterization of spinel Li_(1.05)Cr_(0.1)Mn_(1.9)O_(4-z)F_z as cathode materials for lithium-ion batteries

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2010年第2期17卷 220-224页

作者： Yan-bin Chen Yang Hu fang lian Qing-guo Liu School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Beijng Easpring Material Technology Co. Ltd. Beijing 100044 China Beijing General Research Institute of Mining ＆ Metallurgy Beijing 100044 China

Samples with the nominal stoichiometry Li1.05Cr0.1Mn1.9O4-zFz（z=0,0.05,0.1,0.15,and 0.2） were synthesized via the solid-state reaction method and characterized by X-ray powder diffraction（XRD）,scanning electron microscopy（SEM）,galvanostatic charge/discharge, and slow rate cyclic voltammetry（SSCV） *** results show that the pure spinel phase indexed to Fd3m can be obtained when z=0, 0.05,and *** substitution of F for O with z≤0.1 contributes to the increase of initial capacity compared with Li1.05Cr0.1Mn1.9O4 spinels. However,when the F-dopant content is designed to be 0.15 and 0.2,the Li1.05Cr0.1Mn1.9O4-zFZ samples deliver relatively low capacity and poor cycling properties at 55℃.

关键词： lithium-ion batteries cathode materials doping electrochemical properties

Estimation method for random sonic fatigue life of thin-walled structure of a combustor liner based on stress probability distribution

在线全文

学校读者我要写书评

暂无评论

航空动力学报 2011年第4期26卷 727-734页

作者： SHA Yun-dong GUO Xiao-peng LIAO lian-fang XIE Li-juan Liaoning Key Laboratory of Digital Technology Simulation and Test Technique College of Power and Energy Engineering Shenyang Aerospace University Shenyang 110136 China Shenyang Aeroengine Research Institute Aviation Industry Corporation of China Shenyang 110015 China

As to the sonic fatigue problem of an aero-engine combustor liner structure under the random acoustic loadings,an effective method for predicting the fatigue life of a structure under random loadings was ***,the probability distribution of Von Mises stress of thin-walled structure under random loadings was studied,analysis suggested that probability density function of Von Mises stress process accord approximately with two-parameter Weibull *** formula for calculating Weibull parameters were *** on the Miner linear theory,the method for predicting the random sonic fatigue life based on the stress probability density was developed,and the model for fatigue life prediction was *** an example,an aero-engine combustor liner structure was *** power spectrum density(PSD) of the vibrational stress response was calculated by using the coupled FEM/BEM(finite element method/boundary element method) model,the fatigue life was estimated by using the constructed *** considering the influence of the wide frequency band,the calculated results were *** analysis shows that the estimated results of sonic fatigue of the combustor liner structure by using Weibull distribution of Von Mises stress are more conservative than using Dirlik distribution to some *** results show that the methods presented in this paper are practical for the random fatigue life analysis of the aeronautical thin-walled structures.

关键词： thin-walled structure sonic fatigue life estimation probability density function(PDF) power spectrum density(PSD)