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Constraints on Cardassian universe from Gamma ray bursts

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science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 1720-1725页

作者： WANG TaiShan1 & LIANG Nan2.1 department of Physics & center for Astrophysics,Tsinghua University,{2. 100084,{3. 2.department of Astronomy,{2. Normal University,{2. 100875,{3. 1. department of Physics & center for Astrophysics Tsinghua University Beijing 100084 China2. Department of Astronomy Beijing Normal University Beijing 100875 China

Constraints on the original Cardassian model and the modified polytropic Cardassian model are examined from the recently derived 42.gamma-ray bursts(GRBs) data calibrated with the method that can avoid the circularity *** results show that GRBs can be an optional observation to constrain the Cardassian *** the GRBs data with the newly de-rived size of baryonic acoustic oscillation peak from the Sloan Digital Sky Survey(SDSS),and the position of the first acoustic peak of the Cosmic Microwave Background radiation(CMB) from Wilkinson Microwave Anisotropy Probe(WMAP),we find Ωm0=0.2.+0.02.0.02.n=0.06+0.07-0.08(1σ) for the original Cardassian model,and Ωm0=0.2.+0.2.0}0.02.n=-0.09+0.2.0}1.91,β=0.82.2.10-0.62.1σ) for the modified polytropic Cardassian model.

关键词： Cardassian Gamma ray burst Cosmic Microwave Background baryonic acoustic oscillation

Source time-function as discriminant using empirical Green's function

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science china Earth sciences 2005年第12期48卷 2118-2122页

作者： HE Yongfeng1,2.& CHEN Xiaofei1 1. department of Geophysics, School of Earth & Space sciences, Peking University,{2. 100871,{3. 2. North-West Institute of Nuclear technology, Xi’an 71002.,{3. 1. department of Geophysics School of Earth & Space Sciences Peking University 100871 Beijing China 2. North-West Institute of Nuclear technology 710024 Xi’an China

The source mechanism of underground nuclear explosions is remarkably different from that of earthquakes in both spatial radiation pattern and source time-function (STF). Small underground nuclear explosions can be used as empirical Green’s functions (EGF) to isolate the source-time spectrum of a large suspected earthquake occurred in a Nuclear Test Site (target area) by the spectral division method. As this study shows, with high-quality data, the quotient spectrum can be transformed to the time domain, yielding the apparent far-field source-time function of the large suspected event. The relative source time-function (RSTF) of a nuclear ex-plosion is usually a simple pulse with a duration of about 1 s., while an earthquake’s is more complicated with a series of pulses and a longer duration. The RSTF can be used as a nice dis-criminant to distinguish the nature earthquakes from underground nuclear explosions in target areas.

关键词： target-area, empirical Green's function, RSTF.

Influence of Ru addition on microstructure and stress-rupture property of Ni-based single crystal superalloys

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Progress in Natural science:Materials International 2010年第1期20卷 61-69页

作者： Jing-yang CHEN~1,Qiang FENG~(1,2.,La-mei CAO~3.Zu-qing SUN~1 1.State Key Laboratory for Advanced Metals and Materials,University of science and {2. {2., {2. 100083.china 2.National center for Materials Service Safety,University of science and {2. {2.,beijing 100083.china 3.National Key Laboratory of science and {2. on Advanced High Temperature Structural Materials, {2. Institute of Aeronautical Materials,beijing 100095,china Univ Sci & Technol beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China Univ Sci & Technol beijing Natl Ctr Mat Serv Safety Beijing 100083 Peoples R China beijing Inst Aeronaut Mat Natl Key Lab Sci & Technol Adv High Temp Struct M Beijing 100095 Peoples R China

The effects of Ru on the microstructure and stress-rupture property were investigated in two experimental Ni-based single crystal superalloys with and without Ru addition(5.1%,mass fraction).The results indicate that the morphology ofγ' precipitates in the dendrite core and interdendritic region are intermediate and nearly spherical,respectively,in the Ru-free alloy after being aged at 1100℃for 8 *** Re partitioning ratio increases due to Ru addition and Ru partitioned preferentially to theγphase in both dendrite core and interdendritic region of the Ru-containing alloy,which results in more negative lattice misfit and more cuboidalγ' ***,theγ' volume fraction increases while the precipitate size and y channel width decreases due to Ru addition in both dendrite core and interdendritic *** addition improves the stress-rupture life at 1100℃/140 MPa significantly due to higherγ' volume fraction,more negative lattice misfit and a well rafting structure as well as lessγchannel width.

关键词： Ni-based superalloys ruthenium elemental partitioning ratio lattice misfit γ’ morphology stress-rupture property

Studies on Barriers for Promotion of Clean technology in SMEs of china

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Chinese Journal of Population,Resources and Environment 2005年第1期3卷 9-17页

作者： Peng Sizhen , Liu Yan , Shi Han 1 2.& Zhong Ping 3.1. The Administrative Centre for china’s Agenda2., {2. 100089, china 2. Yale School of Forestry & Environmental Studies, New Haven CT 06511, the U.S.A. 3. {3. of Environmental science and Engineering, Sichuan University, Chengdu Sichuan 610065, china The Administrative Centre for china’s Agenda2. Beijing 100089 China Yale School of Forestry and Environmental Studies New Haven CT 06511 United States department of Environmental science and Engineering Sichuan University Chengdu Sichuan 610065 China

After more than 10 years efforts on awareness raising and promotion, the concept of cleaner production (CP) has been adopting as a strategic approach to balance economic benefits and environmental protection for china’s industries. However, it is also found that clean technology is difficult to be adopted and implemented in Chinese Small and Medium-sized Enterprises (SMEs) because of certain barriers. This paper investigates these barriers among three stakeholders--governments, enterprises and experts. The Analytic Hierarchy Process (AHP) was employed to prioritize the relative importance of the twenty fine-selected barriers, which were classified into four barrier categories. The findings reveal that the exterior barriers of policy and financial barriers should be stressed rather than the inner barriers of technical and managerial barriers, although they are also very important. Absence of incentives on economic policies, lax enforcement of environmental regulations and high initial capital cost were the most important barriers to adoption of Clean Technologies (CT) in china.

关键词： Cleaner Production Clean Technologies Barrier Study Small and Medium Enterprises

Carbon isotope ratios of C_(4) plants in loess areas of North china

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science china Earth sciences 2006年第1期49卷 97-102页

作者： WANG Guoan1,2.3. HAN Jiamao 2. ZHOU Liping3. XIONG Xiaogang4, TAN Ming2. WU Zhenhai5 & PENG Jun6 1. {2. of Plant Nutrition, china Agricultural University, {2. 100094, china 2. Institute of Geology and Geophysics, Chinese Academy of sciences, beijing 10002., china 3. College of Environmental sciences, MOE Laboratory for Earth Surface Processes, Peking University, {2. 100871, china 4. Institute of Botany, Chinese Academy of sciences, {2. 100093. china 5. Northwest Sci-Tech University of Agriculture and Forestry, Yangling 712.00, china 6. Network center, china Agricultural University, {2. 100094, china 1. department of Plant Nutrition China Agricultural University Beijing 100094 China 2. Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China 3. College of Environmental sciences MOE Laboratory for Earth Surface Processes Peking University Beijing 100871 China 4. Institute of Botany Chinese Academy of Sciences Beijing 100093 China 5. Northwest Sci-Tech University of Agriculture and Forestry Yangling 712100 China 6. Network center China Agricultural University Beijing 100094 China

Carbon isotope ratios (δ^(13.C) of 89 C_4 plant samples were determined fromthe loess area in North china. δ^(13.C values vary between -10.5per thousand and -14.6per thousandwith a mean of -12.6per thousand. Along a precipitation gradient from the semi-moist area to thesemiarid area, then to the arid area, the δ^(13.C values of C_4 plants show a slight decreasingtrend. The δ^(13.C values of C_4 plants in the dry season are found lower than those in the wetseason. These trends are opposite to those observed for C_3.species.

关键词： C4 plants, carbon isotope ratios, loess area.

Monitoring of rice crop using ENVISAT ASAR data

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science china Earth sciences 2006年第7期49卷 755-763页

作者： DONG Yanfang1, 2. SUN Guoqing1,3.& PANG Yong4 1. State Key Laboratory of Remote Sensing science, Institute of Remote Sensing Applications, Chinese Academy of sciences, {2. 100101,{3. 2. Graduate University of Chinese Academy of sciences, {2. 10003.,{3. 3. department of Geography, University of Maryland, College Park, MD 2.742. USA 4. Forest Remote Sensing Lab, Research Institute of Forest Resource and Information technology, Chinese Academy of For-estry, {2. 100091,{3. 1. State Key Laboratory of Remote Sensing science Institute of Remote Sensing Applications Chinese Academy of Sciences Beijing 100101 China 2. Graduate University of Chinese Academy of sciences Beijing 100039 China 3. department of Geography University of Maryland College Park MD 20742 USA 4. Forest Remote Sensing Lab Research Institute of Forest Resource and Information Technology Chinese Academy of Forestry Beijing 100091 China

Because of the cloudy conditions during the rice growth period, rice is one of the agri-cultural crops most suited to monitoring with the SAR instruments. Backscatter response measured by SAR is correlated with rice conditions, including height, density, biomass and structure, which are variable at different growing stages. In this paper, multi-date ENVISAT ASAR Alternating Polarization Mode (APMode) imageries were acquired during the rice crop growing cycle. At the same time, the rice parameters were measured in field. A continuous canopy model was used to compute the back-scattering from rice fields during the growth cycle, and the relationship between rice parameters and radar backscattering coefficients from both ASAR and modeling was analyzed. The effects of polari-zation, incidence angle and polarization on radar backscattering coefficients were analyzed. It was found that simulated radar backscatter has similar trends as ASAR data. This will be meaningful for the further research of rice parameters estimation from ASAR data. Different features show signifi-cantly different signatures in ASAR images and they follow some certain laws, so rice area can be accurately mapped by using multi-temporal SAR images, then rice yield can be estimated.

关键词： rice, ASAR, radar backscattering, model.

Parameter identification theory of a complex model based on global optimization method

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science china(Physics,Mechanics & Astronomy) 2008年第11期51卷 1722-1732页

作者： QU Jie1, JIN QuanLin2.& XU BingYe3.1 College of Automotive Engineering, South china University of {2., Guangzhou 510640, china 2.{3. Research Institute of Mechanical and Electrical {2., {3. 100083. china 3.department of Engineering Mechanics, Tsinghua University, {3. 100084, china 1. College of Automotive Engineering South China University of Technology Guangzhou 510640 China 2. beijing Research Institute of Mechanical and Electrical technology Beijing 100083 China 3. department of Engineering Mechanics Tsinghua University Beijing 100084 China

With the development of computer technology and numerical simulation technology, computer aided engineering (CAE) technology has been widely applied to many fields. One of the main obstacles, which hinder the further application of CAE technology, is how to successfully identify the parameters of the selected model. An elementary framework for parameter identification of a complex model is provided in this paper. The framework includes the construction of objective function, the design of the optimization method and the evaluation of the identified results, etc. The parameter identification process is described in this framework, taking the parameter identification of the superplastic constitutive model considering grain growth for Ti-6Al-4V at 92.°C as an example. The objective function is the weighted quadratic sums of the difference between the experimental and computational data for the stress-strain relationship and the grain growth relationship; the designed optimization method is a hybrid global optimization method, which is based on the feature of the objective function and incorporates the strengths of genetic algorithm (GA), the Levenberg-Marquardt algorithm and the augmented Gauss-Newton algorithm. The reliability evaluation of parameter identification result is made through the comparison between the calculated and experimental results and between the theoretical values of the parameters and the identified ones.

关键词： constitutive model parameter identification theory inverse analysis global optimization

Numerical simulations of the bi-level and branched structure of intracloud lightning flashes

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science china Earth sciences 2006年第6期49卷 661-672页

作者： TAN Yongbo1, TAO Shanchang1, ZHU Baoyou1, MA Ming2.& LU Weitao2.1. School of Earth and Space sciences, University of science and{2. of{3., Hefei 2.3}02.,{3. 2. Chinese Academy of Meteorological sciences, beijing 100081,{3. 1. School of Earth and Space sciences University of Science and Technology of China Hefei 230026 China 2. Chinese Academy of Meteorological sciences Beijing 100081 China

Intracloud (IC) lightning flashes have been simulated in fine resolution (12.5 m) by using a bidirectional stochastic lightning parameterization scheme within 2.dimensional domain. The simu-lated results show that the IC flashes have a bilevel channel structure and the altitudes of the hori-zontal channels are at the same heights of potential wells, which are supported by the previous VHF source observations and balloon soundings of electric field profile in the thundercloud. Further con-clusions are: (1) After an IC flash is initiated near the boundary between positve and nagetive charge zone, the negative (or positive) leader tends to propagate into the positive (or negative) charge zone. Both types of positive and negative IC flashes have been reproduced and their polarity depends on the up and down disposition of the positive and negative charge regions. (2. The extension range of leaders is correlative with the cloud charge distribution. The leader is possible to extend through the inverted charge region all over where it is extending, but keeps away from the isolated charge area of the same polarity. (3. The channel structures also depend on the electric potential distributions in the thundercloud. Before propagating into the central area of potential wells, the leader tends to extend along the direction with the maximum of potential gradient. Once extending away from the center of potential wells, the leader tends to extend along the direction with the slowest potential change. (4) The IC flash channels have the fractal feature with fractal dimension 1.45 before leaders pass through the central area of charge regions. The exponent decreases rapidly once leaders extend into the low-density charge regions. (5) The induced charges of opposite polarity are deposited in the leader channels within preexisting positive and negative charge regions during IC flash discharges. This causes a new and complicated charge distribution in the thundercloud, and the potential

关键词： IC, lightning parameterization, branched bilevel structure, fractal feature, propagation tendency.

Application of asymptotic waveform approximation technique to hybrid FE/BI method for 3. scattering

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science in china(Series F) 2007年第1期50卷 124-134页

作者： PENG Zhen1,2.3.& SHENG XinQing2.1 Institute of Electronics, Chinese Academy of sciences, {2. 100080, china 2.{3. of Electronic Engineering, {2. Institute of technology, {2. 100081, china 3.Graduated University of Chinese Academy of sciences, {2. 10003., china 1. Institute of Electronics Chinese Academy of Sciences Beijing 100080 China 2. department of Electronic Engineering Beijing Institute of Technology Beijing 100081 China 3. Graduated University of Chinese Academy of sciences Beijing 100039 China

The asymptotic waveform evaluation （AWE） technique is a rational function approximation method in computational mathemetics, which is used in many appllcations in computational electromagnetlca. In this paper, the performance of the AWE technique in conjunction with hybrid finite element/boundary integral （FE/BI） method is firstly Inveetlgeted. The formuletlon of the AWE applied in hybrid FE/BI method is given in detail. The characteristic implementation of the application of the AWE to the hybrid FE/BI method is discussed. Numarlcel results demonstrate that the AWE technique can greatly speed up the hybrid FE/BI method to acquire wide-band and wide-angle backecatter radar-cross-section （RCS） by complex targets.

关键词： hybrid FE/BI AWE electromagnetic scattering RCS