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Oxygen vacancy induced magnetism in BaTiO_(3-δ) and Nb:BaTiO_(3-δ) thin films

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Science china(physics,Mechanics & Astronomy) 2010年第5期53卷 852-855页

作者： YANG Fang,JIN KuiJuan,LU HuiBin,HE Meng,WANG Cong,WEN Juan & YANG GuoZhen beijing National Laboratory for Condensed Matter physics,institute of physics,chinese academy of sciences,beijing 100190,china beijing National Laboratory for Condensed Matter physics Institute of Physics Chinese Academy of Sciences Beijing China

The unusual magnetic properties are observed in oxygen deficient BaTiO3-δ(BTO) and Nb:BaTiO3-δ(BNTO) thin films fabricated on SrTiO3 substrates by laser molecular beam *** distinct magnetic hysteresis loops are observed in the oxygen deficient BTO and BNTO thin films in a temperature range of 5 to 300 K,whereas the diamagnetism is observed in both BTO and BNTO annealed at 1 atm of *** dopant Nb only enhances the magnetization in BNTO thin films,but has little effect on the *** magnetism of BTO and BNTO films is proposed to be the oxygen vacancies by origin.

关键词： oxygen vacancy magnetism BaTiO3-δ(BTO) Nb:BaTiO3-δ(BNTO) thin films

Semi-analytical analysis of the response of the air temperature over the land surface to the global vegetation distribution

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chinese Science Bulletin 2009年第14期54卷 2499-2505页

作者： LIU Fei1,2 & CHAO JiPing3,4 1 institute of Atmospheric physics, chinese academy of sciences, beijing 100029, china 2 Graduate University of chinese academy of sciences, beijing 100049, china 3 National Marine Environmental Forecasting Center, beijing 100081, china 4 First institute of Oceanography, State Oceanic Administration of china, Qingdao 266061, china institute of Atmospheric physics chinese academy of sciences Beijing China Graduate University of chinese academy of sciences Beijing China National Marine Environmental Forecasting Center Beijing China First institute of Oceanography State Oceanic Administration of China Qingdao China

Response of the air temperature over the land surface to the global vegetation distribution is investigated, using a three-dimensional governing equation to simulate the steady, large-scale, limited amplitude perturbation of the free, inviscid and adiabatic atmosphere. The adoption of the static equation leads to a temperature governing equation in the terrain following coordinate. With the prescribed temperature as the upper boundary condition and the radiation balance as the lower boundary condition, the semi-analytical solution of the global circulation temperature can be calculated. In this article, only the air temperature (at 2 m height) over the land surface is analyzed, and the result suggests that this model can simulate the air temperature pattern over the land surface reasonably. A better simulation occurs when a simple feedback of the albedo on the temperature is included. Two sensitivity experiments are analyzed through this model. One suggests that the air temperature over the land surface descends obviously when the land surface is covered with ice all over, while another suggests that the air temperature rises a little when the land surface is covered with forest except the ice-covered area. This model appears to be a good tool to study the response of the air temperature to the vegetation distribution. Limitations of the model are also discussed.

关键词：空气温度植被分布陆地表面反应解析分析模拟模式控制方程边界条件

A mixed method for measuring low-frequency acoustic properties of macromolecular materials

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Science china(physics,Mechanics & Astronomy) 2006年第6期49卷 729-739页

作者： LIU Hongwei1,YAO Lei1,3,ZHAO Hong1,3,ZHANG Jichuan2,3 & XUE Zhaohong2 1. National Key Laboratory of Acoustics,institute of Acoustics,chinese academy of sciences,beijing 100080,china 2. institute of Chemistry,chinese academy of sciences,beijing 100080,china 3. Graduate University of chinese academy of sciences,beijing 100049,china National Key Laboratory of Acoustics Institute of Acoustics Chinese Academy of Sciences Beijing China Graduate University of chinese academy of sciences Beijing China institute of Chemistry Chinese Academy of Sciences Beijing China

A mixed method for measuring low-frequency acoustic properties of macro-molecular materials is presented. The dynamic mechanical parameters of materials are first measured by using Dynamic Mechanical Thermal Apparatus(DMTA) at low frequen-cies,usually less than 100 Hz; then based on the Principles of Time-Temperature Super-position (TTS),these parameters are extended to the frequency range that acousticians are concerned about,usually from hundreds to thousands of hertz; finally the extended dynamic mechanical parameters are transformed into acoustic parameters with the help of acoustic measurement and inverse analysis. To test the feasibility and accuracy,we measure a kind of rubber sample in DMTA and acquire the basic acoustic parameters of the sample by using this method. While applying the basic parameters to calculating characteristics of the sample in acoustic pipe,a reasonable agreement of sound absorp-tion coefficients is obtained between the calculations and measurements in the acoustic pipe.

关键词： low-frequency acoustic properties,dynamic mechanical properties,Principles of Time-Temperature Superposition,acoustic pipe,sound absorption coefficient.

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

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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

Biologically effective radiation of solar ultraviolet radiation and the depletion of stratospheric ozone

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Journal of Environmental sciences 1994年第3期6卷 373-381页

作者： Wang Shaobin Su Weihan(Research Center for Eco-Environmental sciences,chinese academy of sciences),beijing 100085,china) Wei Dingwen(institute of Atmospheric physics,chinese academy or sciences),beijing 100029,china)

Based on the biological action spectra and total UV-B radiation in the atmosphere,the effective UV-dose for DNA, erythema,and plant at different seasons in the last decade,and their future change in beijing area were *** results indicate that the maxi- mum of biologically effective radiation dose at noontime is in July and the minimum is in January. From 1980 to 1989 biologically effective radiation dose have increased with the average rates of about 0.6,0.7 and 1.1 mW/m￣2 per year for January, April and October,while in July the trend of radiation dose is not ln evidence. For 1% reduction of ozone concentration radiation amplification factor for DNA,erythema and plant are 2.3,2.3 and 1.4 and for 30% reduction of ozone concentration the RAF for DNA,erythema and plant are 4.2,4.0 and 2.1,respectively.

关键词： UV-B ozone depletion biological effects solar radiation.

Input function and simulated distributions of tritium in the North Pacific

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Science china Earth sciences 2010年第3期53卷 441-453页

作者： BA Qi1,2 & XU YongFu1 1 State Key Laboratory of Atmospheric Boundary Layer physics and Atmospheric Chemistry, institute of Atmospheric physics, chinese academy of sciences, beijing 100029, china 2 Graduate University of chinese academy of sciences, beijing 100049, china State Key Laboratory of Atmospheric Boundary Layer physics and Atmospheric Chemistry Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Graduate University of chinese academy of sciences Beijing China

An ocean general circulation model (OGCM) of the North Pacific with a southern open boundary condition is used to simulate the distribution and transport of tritium in the North Pacific. First, the observed tritium in precipitation dataset of GNIP/ISOHIS is chosen, and used to develop an input function of tritium for the model domain from 1951 to 1997 in terms of the triangulation for interpolation. Then, the input function is used as an upper flux for the tritium model. The OGCM with tritium is integrated for 47 years with the initial condition of zero tritium concentrations. Compared with the observations from GEOSECS and WOCE, the model generates a meridional gradient of surface tritium concentrations and the high tritium concentrations in the subsurface layer, which is consistent with that indicated in the observations. The simulated time series of total tritium fluxes from the atmosphere to the ocean shows a spike in 1963. The total inventory of tritium in the ocean changes slowly with time after 1975. Tritium enters the higher-latitude region, and then is mainly transported by the subsurface process towards the equatorial region, which is well simulated in the model. However, the difference mainly occurs at 30°N–40°N, which can be seen also in the simulation of CFCs. This difference may partly originate from the insufficient description of physical processes in the OGCM. Nevertheless, some uncertainties exist in the development of the tritium input function, which can also influence the simulated results.

关键词： North Pacific basin-wide ocean general circulation model tritium input function tritium distributions

THE RESPONSES OF THE THIRD GENERATION OF IAP/LASG OCEANIC GCM TO DIFFERENT EXTERNAL FORCING

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Journal of Hydrodynamics 2001年第3期13卷 107-114页

作者： Li Wei, Liu Hai long, Zhang Xue hong LASG institute of Atmospheric physics, chinese academy of sciences, beijing 100029, china Fang Guo hong institute of Oceanology, chinese academy of sciences, Qingdao 266071, china Key Laboratory of Marine Scienc LASG Inst. of Atmospheric physics Chinese Acad. of Sci. Beijing 100029 China

Forced by different wind stress as well as different surface heat flux, three 10 year integrations using L30T63 oceanic GCM are carried out. The annual mean state, seasonal cycle and interannual variability of the upper ocean temperature over the tropical Pacific are examined. In the case of annual mean state of sea surface temperature, relults from D15c and D15e are alike and have good agreement with NCEP data. Defects in D15d include the excessively higher SST over warm pool region and higher SST along the eastern coast. The corresponding westward displacement of cold water is also noticeable. All the experiments represent the annual cycle of SST in the eastern equatorial Pacific while the amplitudes are weaker compared to NCEP data. The intensity of interannual variability of SST in eastern equatorial Pacific is markedly improved D15d and is perfectly comparative with that from NCEP data. The eastward propagations of the interannual variability of upper ocean heat content along the equator in 1982/1983 E1 Nio are well represented in all experiments. On the onset stage of 1982/1983 E1 Nio, the modeled interannual variabilities of SST and heat content are generally the same among all experiments. It is the weakest interannual variability of surface heat flux, which damps SST variability during the mature phase of E1 Nio, that results in a most intensified SST variability in D15d.

关键词： Oceanic GCM tropical pacific SST

The formation and stability of Si_(1-x)C_x alloys in Si implanted with carbon ions

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chinese Science Bulletin 2001年第3期46卷 200-204页

作者： WANG Yinshu, LI Jinmin, JIN Yunfan, WANG Yutian, SUN Guosheng & LIN Lanying1. Department of physics, beijing Normal University, beijing 100875, china 2. institute of Semiconductors, chinese academy of sciences, beijing 100083, china 3. institute of Modern physics, chinese academy of sciences, Lanzhou 730000, china Department of physics Beijing Normal University Beijing China institute of Semiconductors Chinese Academy of Sciences Beijing China institute of Modern physics Chinese Academy of Sciences Lanzhou China

Si1-xCx alloys of carbon (C) concentration between 0.6%-1.0% were grown in Si by ion implantation and high temperature annealing. The formation of Si1-xCx alloys under different ion doses and their stability during annealing were studied. If the implanted dose was less than that for amorphizing Si crystals, the implanted C atoms would like to combine with defects produced during implantation and it was difficult to form Si1-xCx alloys after being annealed at 850℃. With the increment of implanted C ion doses, the lattice damage increased and it was easier to form Si1-xCx alloys. But the lattice strain would become saturate and only part of implanted carbon atoms would occupy the substitutional positions to form Si1-xCx alloys as the implanted carbon dose increased to a certain degree. Once Si1-xCx alloys were formed, they were stable at 950℃, but part of their strain would release as the annealing temperature increased to 1 000℃. Stability of the alloys became worse with the increment of carbon

关键词： ion implantation Si1-xCx alloys stability of Si1-xCx alloys.

Regional soil moisture simulation for Shaanxi Province using SWAT model validation and trend analysis

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Science china Earth sciences 2010年第4期53卷 575-590页

作者： LI MingXing1,2,MA ZhuGuo1 & DU JiWen3 1 Key Laboratory of Regional Climate-Environment Research for Temperate East Asia,institute of Atmospheric physics,chinese academy of sciences,beijing 100029,china 2 Graduate University of chinese academy of sciences,beijing 100049,china 3 Shaanxi Administration of Meteorology,Xi’an 710014,china Key Laboratory of Regional Climate-Environment Research for Temperate East Asia Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Graduate University of chinese academy of sciences Beijing China Shaanxi Administration of Meteorology Xi’an China

The soil moisture in Shaanxi Province,a region with complex topography,is simulated using the distributed hydrological model Soil Water Assessment Tool(SWAT).Comparison and contrast of modeled and observed soil moisture show that the SWAT model can reasonably simulate the long-term trend in soil moisture and the spatiotemporal variability of soil moisture in the *** to NCEP/NCAR and ERA40 reanalysis of soil moisture show that the trend of variability in soil moisture simulated by SWAT is more consistent with the *** model results suggested that high soil moisture in surface soil layers appears in the southern Shaanxi with high vegetation cover,and the Qinling mountainous region with frequent orographic *** deeper soil layers,high soil moisture appears in the river basins and *** regional soil moisture showed a generally decreasing trend on all soil layers from 1951 to 2004,with a stronger and significant decreasing trend in deeper soil layers,especially in the northern parts of the province.

关键词： SWAT soil moisture content simulation validation trend analysis