检索结果-南通市图书馆

Interference pattern generation and simulation in the single beam of a white light continuum

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2010年第6期53卷 1060-1064页

作者： YU ZhiHao & WENG YuXiang Laboratory of Soft Matter physics,institute of physics,chinese academy of sciences,and National Laboratory of condensed Matter physics,beijing 100190,china Laboratory of Soft Matter physics Institute of Physics Chinese Academy of Sciences and National Laboratory of Condensed Matter Physics Beijing China

We demonstrate the interference phenomenon in the White Light Continuum(WLC) generated by a single femtosecond laser beam. Different kinds of spatial interference patterns of the WLC generation under various conditions were investigated. The spatial patterns were attributed to interference between the filaments in the WLC generated by the fundamental laser beam yielding the diffraction effect from spatial confinement. Simulations of different patterns were performed. By comparing the results of simulation with those of experiments,the distances of several micrometers between the neighboring filaments can be derived,which agree with the literature values from direct measurements.

关键词： interference supercontinuum generation ultrafast nonlinear optics

Nonlinear interactions between gravity waves and background winds

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2007年第6期17卷 639-644页

作者： Liu Xiao1,2.and Xu Jiyao1(1. State Key Laboratory for Space Weather, center for Space Science and Applied Research, chinese academy of sciences,{2., china 2. Graduate University of chinese academy of sciences, beijing 100039, china) State Key Laboratory for Space Weather Chinese Academy of Sciences Beijing 100080 China center for Space Science and Applied Research Chinese Academy of Sciences Beijing 100080 China Graduate University Chinese Academy of Sciences Beijing 100039 China

Using the nonlinear propagating gravity waves (GW) model in the two-dimensional compressible atmosphere and the linear GW theory, the process of GW propagation in different background winds, e.g. the direction of the background wind is opposite to (dead wind) or the same as (tail wind) the direction of the horizontal phase velocity of GW, is studied. The results show that the dead wind prolongs the vertical wavelength and accelerates GW propagation. Therefore, GW propagates up to a higher height becomes instable in a short time and eventually induces an inverse jet flow. Then, the vertical wavelength is becoming short due to the nonlinear interactions between GW and the inverse jet flow. The vertical wavelength and group velocity decrease after GW propagates into the tail wind. The initial instable time is delayed. Although most of GW is trapped in the instable region, some of GW propagates above the instable region. Compared with GW propagation in the tail wind, the nonlinear interactions between GW and the dead wind are also strong. In contrast, the linear GW theory predicts that GW can propagate freely in the dead wind. The vertical wavelength simulated by the nonlinear numerical model is different from that predicted by the linear theory greatly after GW propagates into the dead wind.

关键词： gravity waves background winds vertical group velocity vertical wavelength nonlinear interactions.

PREPARATION AND PROPERTIES OF ETHYL-CYANOETHYL CELLULOSE/POLYACRYLIC ACID COMPOSITE FILMS WITH REFLECTION COLORS

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

chinese Journal of Polymer Science 2001年第3期19卷 277-282页

作者： Yong Huang institute of Chemistry, chinese academy of sciences,{2. china Laboratory of Cellulose and Lignocellulosics Chemistry Guangzhou institute of Chemistry chinese academy of sciences, Guangzhou 510650, china 中科院化学所北京

Ethyl-cyanoethyl cellulose [(E-CE)C]/acrylic acid (AA) becomes a cholesteric liquid crystalline solution withvivid colors when the (E-CE)C concentration is 42.wt%～52.wt%. (E-CE)C/polyacrylic acid (PAA) composites withcholesteric structure were prepared by polymerzing AA in (E-CE)C/AA liquid crystalline solutions. The layers of orderedpolymer chains in the cholesteric phase were inclined during polymerization and the degree of the inclination depended onthe polymerization temperature and the concentration of the solution before polymerization. The cholesteric structure in thecomposites could not be changed when temperature was lower than 100℃. Cross-linking of the PAA in compositesimproved their water-resistance. The cholesteric order of the composites without cross-linking was destroyed when theywhere immersed in water. The color derived from the selective reflection of the cholesteric phase of the cross-linkedcomposites turned from blue to red after the composites absorbed water. The color of the composites could be returned to theoriginal one when the absorbed water was removed from the swollen composites.

关键词： Cholesteric structure Composites Selective reflection Liquid crystalline solutions

MOLECULAR SIMULATION STUDY ON THE CHANGE OF POLYMER STRUCTURE DURING YIELDING

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Polymer Science 2001年第5期19卷 527-529页

作者： Chen-guang Xu Tai-ning Liang Juan Sun Xiao-zhen Yang State Key Laboratory of Polymer physics and Chemistry center for Molecular Science, {2. of Chemistry chinese academy of sciences, beijing 100080 china 中科院化学所高分子物理与化学国家重点实验室北京

A better understanding of a recently raised argument on whether there occurs a structure change during yielding has been acquired by using molecular simulation. That is, when monitoring the displacements of all atoms before and after the yield, a structure transition does occur, which is the 'atomic jump' that coordinates the amount of the atoms in the polymer and makes a large step beyond similar to0.05 nm for all those atoms. Results indicate that the complex of polymer chain packing induces the multiple atomic jumps around the yield point. This explains why polymers have a broader yielding peak.

关键词： polymer deformation yield structure transition atomic jump multiple yields

Comparison of dark energy models:A perspective from the latest observational data

在线全文

学校读者我要写书评

暂无评论

中国科学：物理学、力学、天文学英文版 2010年第9期53卷 1631-1645页

作者： LI Miao1,2.LI XiaoDong2.3 & ZHANG Xin1,4 1Kavli institute for Theoretical physics{2.,chinese academy of sciences,beijing 100190,china 2.ey Laboratory of Frontiers in Theoretical physics,institute of Theoretical physics,chinese academy of sciences,beijing 100190,china 3Interdisciplinary center for Theoretical Study,University of Science and Technology of{2.,Hefei 2.002.,china 4Department of physics,College of sciences,Northeastern University,Shenyang 110004,china Kavli institute for Theoretical physics{2. Chinese Academy of Sciences Beijing China Key Laboratory of Frontiers in Theoretical physics Institute of Theoretical Physics Chinese Academy of Sciences Beijing China Interdisciplinary center for Theoretical Study University of Science and Technology of China Hefei China Department of physics College of Sciences Northeastern University Shenyang China

We compare some popular dark energy models under the assumption of a flat universe by using the latest observational data including the type Ia supernovae Constitution compilation,the baryon acoustic oscillation measurement from the Sloan Digital Sky Survey,the cosmic microwave background measurement given by the seven-year Wilkinson Microwave Anisotropy Probe observations and the determination of H0 from the Hubble Space *** comparison statistics such as the Bayesian and Akaike information criteria are applied to assess the worth of the *** statistics favor models that give a good fit with fewer *** on this analysis,we find that the simplest cosmological constant model that has only one free parameter is still preferred by the current *** other dynamical dark energy models,we find that some of them,such as the αdark energy,constant w,generalized Chaplygin gas,Chevalliear-Polarski-Linder parametrization,and holographic dark energy models,can provide good fits to the current data,and three of them,namely,the Ricci dark energy,agegraphic dark energy,and Dvali-Gabadadze-Porrati models,are clearly disfavored by the data.

关键词： dark energy models observational constraints model comparison information criteria

New evidence for lack of CMB power on large scales

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2010年第3期53卷 567-570页

作者： LIU Hao1 & LI TiPei1,2.3 1 Key Laboratory of Particle Astrophysics, institute of High Energy physics, chinese academy of sciences, beijing 100049, china 2.Department of physics & center for Astrophysics, Tsinghua University, beijing 100084, china 3 Department of Engineering physics & center for Astrophysics, Tsinghua University, beijing 100084, china Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing China Department of physics & center for Astrophysics Tsinghua University Beijing China Department of Engineering physics & center for Astrophysics Tsinghua University Beijing China

A digitalized temperature map is recovered from the first light sky survey image published by the Planck team, from which an angular power spectrum of the cosmic microwave background (CMB) is derived. The amplitudes of the low multipoles (low-l) measured from the preliminary Planck power spectrum are significantly lower than those reported by the WMAP team. Possible systematical effects are far from enough to explain the observed low-l differences.

关键词： cosmology cosmic microwave background data analysis

Multiple Melting Endotherms of Syndiotactic Polystyrene in β Crystalline Form

在线全文

学校读者我要写书评

暂无评论

chinese Chemical Letters 2000年第4期11卷 367-368页

作者： Zhen Hua YUAN De Yan SHEN (Polymer physics Laboratory, center for Molecular Science. {2. of Chemistry. chinese academy of sciences, beijing 100080) Polymer physics Laboratory Center for Molecular Science Chinese Academy of Sciences Beijing 100080 China

A series of syndiotactic polystyrene (SPS) samples in β crystalline form were prepared by cooling from the melt at various cooling rates. The effects of cooling rate from the melt, and DSC heating rate on the multiple melting behaviors of β crystals were investigated by differential scanning calorimetry (DSC) and modulated differential scanning calorimetry (MDSC), from which the *** the multiple melting behavior was ascribed to the occurring of a recrystallization process.

关键词： Multiple melting behavior syndiotactic polystyrene recrystalliation.

Anomalous magnetotransport in LaMn_(1-x)Te_xO_3

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2009年第7期52卷 987-992页

作者： TAN GuoTai1,2. CHEN ZhengHao3 & ZHANG XiaoZhong4,5 1 Key Laboratory of Beam Technology & Materials Modification of the Ministry of Education, institute of Low Energy Nuclear physics, {2. Normal University, {2. 100875, china 2.{2. Radiation center, {2. 100875, china 3 Laboratory of Optical physics, institute of physics, chinese academy of sciences,{12., china 4 Key Laboratory of Advanced Materials of the Ministry of Education, Department of Materials Science and Engineering, Tsinghua University, {2. 100084, china 5 {2. National center for Electron Microscopy, Tsinghua University, {2. 100084, china Key Laboratory of Beam Technology & Materials Modification of the Ministry of Education Institute of Low Energy Nuclear Physics Beijing Normal University Beijing China beijing Radiation center Beijing China Laboratory of Optical physics Institute of Physics Chinese Academy of Sciences Beijing China Key Laboratory of Advanced Materials of the Ministry of Education Department of Materials Science and Engineering Tsinghua University Beijing China beijing National center for Electron Microscopy Tsinghua University Beijing China

The LaMn1-xTexO3+δ (x=0.1, 0.2. 0.3) were synthesized using solid-state reaction method for the first time. X-ray photoemission spectrum (XPS) shows that in the samples the Te ions have a valence of Te4+, and Mn3+ ions are partly converted into Mn2. and Mn4+ due to the excess oxygen and Te doping. The magnetotransport associated with Mn2., Mn3+ and Mn4+ was investigated. The experimental results show that the samples are insulator at 0 T when the amount of Mn3+ is much larger or less than the sum of Mn2. and Mn4+; by contrast, the samples display metal to insulator transition with increasing temperature when the amount of Mn3+ is close to the sum of Mn2. and Mn4+. These anomalous magnetotransport behaviors were analyzed in the frame of the double-exchange (DE) mechanism.

关键词： colossal magnetoresistance La-Te-Mn-O magnetotransport

POLYMETHYLMETHACRYLATE FILMS IN THE STATE OF HIGH GLOBAL CHAIN ORIENTATION BUT NEARLY RANDOM SEGMENTAL ORIENTATION

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Polymer Science 1999年第3期17卷 215-220页

作者： Rui Song Jing Chen Jin-gui Gao Xin Lin Qing-rong Fan Polymer physics Laboratory, institute of Chemistry,{2., beijing 100080, china 中科院化学所高分子物理及化学国家重点实验室北京 100080 中科院化学所高分子物理及化学国家重点实验室北京

PMMA films in the high global chain orientation and nearly random segmental orientation (GOLR) state were prepared by uni-axially drawing at temperatures 2. similar to 30 degrees C above its glass transition temperature, T-g, and their isotropic and anisotropic properties were studied. Experimental results show that this kind of amorphous state, the GOLR state, is nearly isotropic in optical birefringence, IR-dichroism and X-ray diffraction patterns, but is very anisotropic in behaviors of thermal expansion, solvent-swelling and stress-strain.

关键词： orientation uniaxial stretching polymethylmethacrylate optical birefringence WAXD infrared spectroscopy