检索结果-南通市图书馆

Estimating the largest Lyapunov exponent in a multibody system with dry friction by using chaos synchronization

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2006年第3期22卷 277-283页

作者： Shihui fu qi Wang School of Science Beijing University of Aeronautics and Astronautics Beijing 100083 China

Using the properties of chaos synchronization, the method for estimating the largest Lyapunov exponent in a multibody system with dry friction is presented in this paper. The Lagrange equations with multipliers of the systems are given in matrix form, which is adequate for numerical calculation. The approach for calculating the generalized velocity and acceleration of the slider is given to determine slipping or sticking of the slider in the systems. For slip-slip and stick-slip multibody systems, their largest Lyapunov exponents are calculated to characterize their dynamics.

关键词： Multibody system Dry friction Lyapunov exponent Chaos synchronization

Monolayer transition metal disulfide: Synthesis, characterization and applications

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2016年第3期26卷 221-231页

作者： qi fu Bin Xiang Department of Materials Science & Engineering CAS Key Lab of Materials for Energy Conversion and Synergetic Innovation Center of Quantum Information & Quantum Physics University of Science and Technology of China

Two-dimensional transition metal dichalcogenides（2D TMDCs） has aroused tremendous attention in recent years, because of their remarkable properties originated from their unique structure. In this review we report th... 详细信息

关键词： Transition metal disulfide Layered-structure Field effect transistor Photoresponse

An Example of Embedded Singular Continuous Spectrum for Discrete Schrödinger Operators

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 Mathematica Sinica,English Series 2024年第8期40卷 1837-1849页

作者： Zheng qi fu Xiong LI Laboratory of Mathematics and Complex Systems(Ministry of Education) School of Mathematical SciencesBeijing Normal UniversityBeijing 100875P.R.China

We present an example of a potential such that the corresponding discrete Schrödinger operator has singular continuous spectrum embedded in the absolutely continuous spectrum.

关键词： Sparse potentials singular continuous spectrum Prüfer variables

Effect of C-Tetramethyl Calix[4]resorcinarene Acrylate on Curing Behavior and Film Properties of Thiol-acrylate Coating System

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2009年第5期25卷 760-766页

作者： fu qi SHI Wen-fang Joint Laboratory of Polymer Thin Films and Solution Department of Polymer Science and Engineering University of Science and Technology of China Hefei 230026 P. R. China

An octa-functional acrylate of C-tetramethyl calix[4]resorcinarene（CMC-4-RA） was facilely synthesized and characterized with ^1H NMR, ^13C NMR and FTIR spectroscopy. The CMC-4-RA was added to a thiol-acrylate system with different mass ratios, and exposed to a middle pressure mercury lamp. The maximum photopolymerization rate and final vinyl group conversion in the cured film increased greatly along with CMC-4-RA addition that was monitored with Photo-DSC. The tensile strength and pendulum hardness were improved significantly after the addition of CMC-4-RA. With increasing the content of CMC-4-RA to 60%（mass fraction）, the glass transition temperature increased from 34.2 ℃ to 84.1 ℃; the cross-link density was calculated to be increased from 23.83 mmol/cm^3 to 82.40 mmol/cm^3 according to dynamic mechanical thermal analysis; the thermostability was greatly improved.

关键词： Calixresorcinarene Acrylate UV curing Film

An infrared study of Be stars based on ISO SWS01 spectra

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2009年第7期9卷 770-776页

作者： Pin Zhang Zai-qi fu Cosmic Ray Institute Yunnan University Kunming 650091 China Department of Physics Zhaotong Teachers College Zhaotong 657000 China

The Infrared Space Observatory （ISO） Short-Wavelength Spectrometer （SWS） spectra of 10 Be stars are presented. It can be seen that the Be stars show a diversity in their ISO SWS01 spectral classifications by Kraemer et al., from naked stars, stars associated with dust, stars with warm dust shells, stars with cool dust shells to very red sources. In addition, the Brα/HI（14-6） line flux ratio derived for the sample stars is compared with that of P Cyg, and it is found that the line ratio of Be stars which were investigated show not only lower values as suggested by Waters et al., but also larger values. Therefore, the line ratio cannot be used to judge whether a star is a Be star or not.

关键词： stars circumstellar matter - infrared stars - stars emission-line Be

Evaluation of 3D crustal seismic velocity models in southwest China:Model performance,limitation,and prospects

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2024年第2期67卷 604-619页

作者： Xin WANG Ling CHEN qi-fu CHEN Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing100049China State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing100029China

Southwest China is a tectonically and seismically active region,witnessing strong deformation due to the collision between the Indian and Eurasian *** the subsurface velocity structure of this region is thus important in understanding the tectonics and geodynamic processes of continental collision and in mitigating seismic *** studies have provided various 3D seismic velocity models in southwest ***,discrepancies exist among these models,and less effort has been made to quantify the reliability and accuracy of these existing velocity *** this study,we use regional 3D waveform simulation to evaluate the performance of various regional crustal 3D velocity models in reproducing observed *** particularly focus on two recent earthquake sequence in the region,the 2021 Yunnan Yangbi MS_(6.4) earthquake sequence and the 2022 Sichuan Luding MS_(6.8) earthquake *** tested 3D velocity models include the Southwest China Community Velocity model V1.0,the Unified Seismic Tomography Models for Continental China Lithosphere V2.0,the adjoint full waveform tomography model of the crustal and upper mantle beneath Eastern Tibetan Plateau,and the shallow seismic structure model beneath continental *** results show that the tested 3D velocity models generally capture well long-period(full-waveform tomography model shows a slighter better performance than the other models,especially for the body-waves,highlighting the advantages

关键词： Southwest China Seismic tomography models Shallow Structures Waveform simulation Model evaluation

Overview of deep structures under the Changbaishan volcanic area in Northeast China

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2019年第6期62卷 935-952页

作者： qi-fu CHEN Yinshuang AI Yun CHEN Key Laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences College of Earth and Planetary Sciences University of Chinese Academy of Sciences Institutions of Earth Science Chinese Academy of Sciences State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences

The Changbaishan volcano is an active and considerably hazardous volcano located on the border of China and North Korea. This paper summarizes a series of geophysical surveys as well as seismological and volcano-observational networks around the Changbaishan volcanic area. We characterize deep structures related to the Changbaishan volcanic area. The prominent low-velocity anomalies and low-resistance bodies associated with the magma system under the Changbaishan volcano were detected in the crust and upper mantle, and high-velocity anomalies were imaged within the mantle transition zone,suggesting that the origin of the Changbaishan volcano is related to the subducted Pacific slab. However, there exist a few major obstacles for comprehensively elucidating the deep structure of the Changbaishan volcano as well as for the preparedness for and response toward future volcanic unrest and activity. It is essential to collect data from both China and Korean Peninsula to image the deep structure beneath the Changbaishan volcanic area. A multi-disciplinary approach comprising seismological investigations, deformation information from GNSS and InSar, and gravity and magnetotelluric surveying is a reliable manner for imaging high-resolution structures and fluid movement for the spatial distribution and variation of the volcanic magma *** effective volcano-monitoring network system is considerably important to improve hazard assessments and characterize the potential future eruption of the Changbaishan volcano.

关键词： Changbaishan volcano Deep structure Geophysical observation

Altered profiles of nuclear matrix proteins during the differentiation of human gastric mucous adenocarcinoma MGc80-3 cells

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2005年第30期11卷 4628-4633页

作者： Chun-Hong Zhao qi-fu Li Laboratory of Cell Biology the Key Laboratory of Ministry of Education for Cell Biology and Tumor Cell Engineering School of Life Sciences Xiamen University Xiamen 361005 Fujian Province China

AIM： To find and identify specific nuclear matrix proteins associated with proliferation and differentiation of carcinoma cells, which will be potential markers for cancer diagnosis and targets in cancer therapy. METHODS： Nuclear matrix proteins were selectively extracted from MGcS0-3 cells treated with or without hexamethylamine bisacetamide （HMBA）, and subjected to 2-D gel electrophoresis. The resulted protein patterns were analyzed by Melanie software. Spots of nuclear matrix proteins differentially expressed were excised and subjected to in situ digestion with trypsin. Peptide masses were obtained by matrix-assisted laser-desorption/ ionization time of flight mass spectrometry （MALDI-TOFMS） analysis and submitted for database searching using Mascot tool. RESULTS： The MGc80-3 cells were induced into differentiation by HMBA. There were 22 protein spots which changed remarkably in the nuclear matrix, from differentiation of MGcS0-3 cells compared to control. Eleven of which were identified. Seven proteinsactin, prohibitin, porin 31HL, heterogeneous nuclear dbonucleoprotein A2/B1, vimentin, ATP synthase, and heat shock protein 60 were downregulated, whereas three proteins - heat shock protein gp96, heat shock protein 90-beta, and valosin-containing protein were upregulated, and the oxygen-regulated protein was only found in the differentiated MGc80-3 cells. CONCLUSION： The induced differentiation of carcinoma cells is accompanied by the changes of nuclear matrix proteins. further characterization of those proteins will show the mechanism of cellular proliferation and differentiation, as well as cancer differentiation.

关键词： Nuclear matrix proteins Cell differentiation Human gastric mucous adenocarcinoma MGc80-3 Hexamethylamine bisacetamide

Optimization-based particle filter for state and parameter estimation

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 Systems Engineering and Electronics 2009年第3期20卷 479-484页

作者： Li fu qi Fei Shi Guangming Zhang Li School of Electronic Engineering Xidian Univ. Xi'an 710071 P. R. China

In recent years, the theory of particle filter has been developed and widely used for state and parameter estimation in nonlinear/non-Gaussian systems. Choosing good importance density is a critical issue in particle filter design. In order to improve the approximation of posterior distribution, this paper provides an optimization-based algorithm （the steepest descent method） to generate the proposal distribution and then sample particles from the distribution. This algorithm is applied in 1-D case, and the simulation results show that the proposed particle filter performs better than the extended Kalman filter （EKF）, the standard particle filter （PF）, the extended Kalman particle filter （PF-EKF） and the unscented particle filter （UPF） both in efficiency and in estimation precision.

关键词： importance density particle filter extend Kalman filter