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Study on H atoms diffusion and adsorption properties of MgH_2-V systems

science china(Technological sciences) 2008年第7期51卷 979-988页

作者： ZHOU DianWu1,2, LIU JinShui3.& PENG Ping3.1 State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, hunan university, changsha 410082. china 2 College of Mechanical and Automatic engineering, hunan university, changsha 410082. china 3.College of materials science and engineering, hunan university, changsha 410082. china 1. State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Changsha 410082 China 2. College of Mechanical and Automatic engineering Hunan University Changsha 410082 China 3. College of materials science and engineering Hunan University Changsha 410082 China

Based on experimental results that VH0.81/MgH2 interface was found during the process of mechanically milling MgH2+5at.%V nanocomposite, H atoms diffusion and adsorption properties of MgH2-V systems have been investigated by using a first-principles plane-wave pseudopotential method based on the density functional theory. The results are as follows. When VH/MgH2 interface is formed due to V alloying MgH2 phase, the vacancy formed by H atoms near VH phase region is more stable than that without V alloying, while vacancy near MgH2 phase region is less stable than that without V alloying. During the process of H atoms diffusion after V alloying, the max migration barrier energy of H atoms in MgH2-V systems is reduced compared with that of MgH2 phase, which means that H atoms diffuse easily. When H diffuses into VH from MgH2 across VH/MgH2 interface, among three substitutions such as the replacement of H for V vacancy, or interstitial site or V atoms, the replacement of H for V vacancy has the strongest diffusion ability, next interstitial site, and finally V atoms site. As far as H adsorbed on different surfaces of VH phase is concerned, physical adsorption is carried out more easily than chemical adsorption, and the behavior of H atoms adsorbed on the surface near VH phase region can be found more easily than that near MgH2 phase region.

关键词： plane-wave pseudopotential theory magnesium hydride diffusion adsorption

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Size distributions and magic number characteristics of cluster configurations formed during solidification processes of liquid metal Al

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science china(Technological sciences) 2006年第2期49卷 172-187页

作者： LIU Rangsu1, LIU Fengxiang1, DONG Kejun1, ZHENG Caixing1, LIU Hairong2, PENG Ping2 & LI Jiyong3.1. Department of Physics, hunan university, changsha 410082. china 2. Department of Material science and {3., hunan university, changsha 410082. china 3. Department of Chemistry, hunan university, changsha 410082. china 1. Department of Physics Hunan University Changsha 410082 China 2. Department of Material science and engineering Hunan University Changsha 410082 China 3. Department of Chemistry Hunan University Changsha 410082 China

A molecular dynamics simulation study has been performed for a large systemconsisting of 100000 liquid metal Al atoms to investigate the formation and magic numbercharacteristics of the cluster configurations formed during the rapid solidification processes. Thecluster-type index method (CTIM) has been adopted to describe various types of clusterconfigurations. The results indicate that the icosahedral clusters (12 0 12 0) and theircombinations play the most important role in the rnicrostructure transitions during solidificationprocesses; for the cluster configurations of different levels formed by various combinations withdiffering numbers of basic clusters, their size distributions possess obvious magic number sequencewhich is in turn as 13.13., 19(21), 26-28(27), 3.-3.(3.), 3.-40, 43.44, 48..., (those in bracket arethe corresponding value in liquid state); the magic numbers correspond to the peak value positionsof the cluster numbers for corresponding level formed with various combinations by 1, 2, 3. 4, 5, 6,7, ...basic clusters, respectively. This magic number sequence is in good agreement with theexperimental results obtained by Harris et al. At the same time, this simulation study also gives ascientific and reasonable explanation to these experimental results.

关键词： liquid metal, solidification processes, cluster configuration, magic numbers, computer simulation.

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Formation and evolution mechanisms of large-clusters during rapid solidification process of liquid metal Al

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science china(Physics,Mechanics & Astronomy) 2005年第1期48卷 101-112页

作者： LIU Rangsu, DONG Kejun, LIU Fengxiang, ZHENG Caixing, LIU Hairong & LI Jiyong Department of Applied Physics, hunan university, changsha 410082. china College of materials {3. and engineering, hunan university, changsha 410082. china College of Chemistry and Chemical engineering, hunan university, changsha 410082. china 1. Department of Applied Physics Human University 410082 Changsha China 2. College of materials science and engineering Hunan University 410082 Changsha China 3. College of Chemistry and Chemical engineering Hunan University 410082 Changsha China

A molecular dynamics simulation study has been performed for the formation and evolution characteristics of nano-clusters in a large-scale system consisting of 400000 atoms of liquid metal Al. The center-atom method combined with pair-bond analysis technique and cluster-type index method (CTIM) has been applied here to describe the structural configurations of various basic clusters. It is demonstrated that both the 1551 bond-type and the icosahedral cluster (12 0 12 0) constructed by 1551 bond-types are dominant among all the bond-types and cluster-types, respectively, in the system and play a critical role in the microstructure transitions of liquid metal Al. The nano-clusters (containing up to 150 atoms) are formed by the combination of some middle and small clusters with distinctly different sizes, through mutual competition by unceasing annex and evolution in a seesaw manner (in turn of obtaining and losing),which do not occur as the multi-shell structures accumulated with an atom as the center and the surrounding atoms are arranged according to a certain rule. This is the essential distinction of nano-cluster in liquid metal from those obtained by gaseous deposition, ionic spray methods, and so on. Though the nano-clusters differ from each other in shape and size, all of them possess protruding corners that could become the starting points of various dendrite structures in the solidification processes of liquid metals.

关键词： liquid metal, solidification process, large-cluster configuration, evolution mechanism, computer simulation.

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Research on Uncertainties in Evaluation Indicator System for Ecological Residential Community

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湖南大学学报（自然科学版） 2009年第S1期36卷 177-181页

作者： JIAO Sheng1,GUAN Chen-yin2,ZENG Guang-ming3.LIU Jian-long1,Zhou Jian-fei3.1.College of Architecture,hunan university,changsha,hunan 410082.china 2.Beijin School,hunan university of Commerce,changsha,hunan 410209,china 3.College of Environmental science and engineering,hunan university,changsha,hunan 410082.china) College of Architecture Hunan University Changsha 410082 China Beijin School Hunan University of Commerce Changsha 410209 China College of Environmental science and engineering Hunan University Changsha 410082 China

In the process of evaluating,the weights of indicators are firstly determined by AHP and Delphi methods;and the values of indicators are normalized by grey correlative coefficient method.A suit of means were put forward,by which a qualitative and quantitative evaluation indicator system suitable for the situation of china and uncertainties can be *** idiographic and operable methods and process were *** the principle of elasticity,hiberarchy and maneuverability,a three-layer evaluation indicator system was established by AHP in Jiuyi ecological residential community,which includes 5 subsystems and 24 *** weights of indicators are measured by AHP and expert estimate and their best indicators values up to par were determined by fuzzy mathematics and *** whole evaluation indicator system not only has an active and practical effect on estimating ecological residential community,but also guides ecological residential community planning.

关键词： ecological residential community evaluation indicator system ecological risk evaluation uncertainty fuzzy mathematics grey correlative coefficient

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Quantitative detection of ING1 mRNA under different gene regulation based on molecular beacon

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Chinese science Bulletin 2006年第17期51卷 2059-2064页

作者： LIU Bin1,2,3.4, WANG Kemin1,2,3.4, XIAO Zhiqiang5,6, WANG Wei1,3.4, TAN Weihong1,2,3.4, SUN Yi5,6, TANG Hongxing1,3.4 & YANG Xiaohai1,3.41. State Key Laboratory of Chemo/Biosensing and Chemometrics, Hu- nan university, changsha 410082. china 2. Life science and Biotechnology Institute,{3., Chang- sha 410082. china 3. Chemistry and Chemical Engineer College,{3., changsha 410082. china 4. hunan engineering Research Center for Bio-Nanotechnology,{3., changsha 410082. china 5. Medical Experiment Research Center, Xiangya Hospital, Central South university, {13. 410008, china 6. Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, {13. 410008, china State Key Laboratory of Chemo/Biosensing and Chemometrics Hunan University Changsha China Life science and Biotechnology Institute Hunan University Changsha China Chemistry and Chemical Engineer College Hunan University Changsha China hunan engineering Research Center for Bio-Nanotechnology Hunan University Changsha China Medical Experiment Research Center Xiangya Hospital Central South University Changsha China Key Laboratory of Cancer Proteomics of Chinese Ministry of Health Changsha China

The effects of drug treatment, gene transfection, and p53.RNA interference (RNAi) on level of ING1 mRNA in tumor cells were quantitatively detected with the help of ING1 molecular beacon (MB)/cRNA standard curve based on MB detection technology. Results showed that the level of ING1 mRNA could be upregulated by 5-FU treatment or ING1 transfection in low expression cell line of MCF-7 and be inhibited by silencing p53.with RNAi technology in normal expression cell line of CNE2. The level of ING1 varied from 7.7×10?16 to 53.4× 10?16 mol/μg total RNA of tumor cells. The results not only provided evidence for the regulation effects of gene expression but also were applied to investigat- ing the interaction of multigenes on signal transduc- tion pathway.

关键词： ING1 RT-PCR 定量分析分子信号 mRNA

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One-pot synthesis of crystalline SnO_2 nanoparticles and their low-temperature ethanol sensing characteristics

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science china(Physics,Mechanics & Astronomy) 2009年第10期52卷 1601-1605页

作者： CHEN YuJin1,2,3.ZHU ChunLing4,WANG LiJiao3.& WANG TaiHong2 1 School of materials science and engineering,Beijing Institute of Technology,Beijing 100081,{3. 2 Micro-Nano Technologies Research Center,hunan university,changsha 410082.{3. 3.College of science,Harbin engineering university,Harbin 150001,{3. 4 College of Material science and Chemical engineering,Harbin engineering university,Harbin 150001,{3. School of materials science and engineering Beijing Institute of Technology Beijing 100081 China Micro-Nano Technologies Research Center Hunan University Changsha 410082 China College of science Harbin Engineering University Harbin 150001 China College of Material science and Chemical engineering Harbin Engineering University Harbin 150001 China

Crystalline SnO2 nanoparticles(NPs) with a diameter less than 6 nm are synthesized using potassium stannate trihydrate as the precursor in a basic *** synthesized NPs can detect ethanol at a ppm level even at 100℃.Furthermore,the NPs have good selectivity to *** excellent ethanol sensing performances are attributed to the small size effect according to the space-charge model.

关键词： SnO2 nanoparticles sensing characteristics

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Robust Fault Diagnosis of Analog Circuits with Tolerances

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湖南大学学报（自然科学版） 2000年第S2期27卷 133-138页

作者： Ying Deng1, Yigang He1 , Xu He2 ,Yichuang Sun3.1. College of Electrical and Information engineering,hunan university, {3. changsha, hunan, china 2. Department of Computer science, hunan university, {3. changsha, hunan, china 3. Department of Ele

A method for robust analog fault diagnosis using hybrid neural networks is proposed. The primary focus of the paper is to provide robust diagnosis using a mechanism to deal with the problem of element tolerances and reduce testing time. The proposed approach is based on the fault dictionary diagnosis method and backward propagation neural network (BPNN) and the adaptive resonance theory (ART) neural network. Simulation results show that the method is robust and fast for fault diagnosis of analog circuits with tolerances.

关键词： Analog circuits Fault diagnosis Tolerances Artificial neural networ|

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Synthesis and magnetic properties of CdS/α-Fe_2O_3.hierarchical nanostructures

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science china(Physics,Mechanics & Astronomy) 2009年第7期52卷 997-1002页

作者： CHEN YuJin1,2,3. SHI XiaoLing1, CAO MaoSheng1 & ZHU ChunLing4 1 School of materials science and engineering, Beijing Institute of Technology, Beijing 100081, {3. 2 Micro-Nano Technologies Research Center, hunan university, changsha 410082. china 3.College of science, Harbin engineering university, Harbin 150001, {3. 4 College of Material science and Chemical engineering, Harbin engineering university, Harbin 150001, {3. 1. School of materials science and engineering Beijing Institute of Technology Beijing 100081 China 2. Micro-Nano Technologies Research Center Hunan University Changsha 410082 China 3. College of science Harbin Engineering University Harbin 150001 China 4. College of Material science and Chemical engineering Harbin Engineering University Harbin 150001 China

CdS/α-Fe2O3.hierarchical nanostructures, where the CdS nanorods grow irregularly on the side surface of α-Fe2O3.nanorods, were synthesized via a three-step process. The diameters and lengths of CdS nanorods can be tuned by changing the ethylenediamine (EDA) and Cd ion concentrations. The magnetic investigations by superconducting quantum interference device indicate that the hierarchical nanostructures have an Morin transition at lower temperature (23. K) than that of the single bulk α-Fe2O3.materials (263.K). Importantly, the hierarchical nanostructures exhibit weakly ferromagnetic characteristics at 3.0 K. A sharp peak assigned to the surface trap induced emission are observed in room temperature PL spectra. Combining with the optoelectronic properties of CdS, the CdS/ α-Fe2O3.hierarchical nanostructures may be used as multi-functional materials for optoelectronic and magnetic devices.

关键词： α-Fe2O3 CdS hierarchical nanostructures magnetic properties

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Effect of pyrolysis temperature and hold time on the characteristic parameters of adsorbent derived from sewage sludge

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Journal of Environmental sciences 2004年第4期16卷 683-686页

作者： ZHAI Yun-bo, WEI Xian-xun, ZENG Guang-ming (Department of Environmental science and engineering,hunan {3., changsha 410082. china. Department of Environmental science and engineering Hunan University Changsha 410082 China. ybzhai@***

According to the Doehlert’s matrix method, the adsorbent derived from sewage sludge was prepared through chemical activation under controlling the pyrolysis temperature and hold time. The characteristic parameters including the total yield, adsorption of methylene blue, adsorption of iodine, BET surface area, micro-pore volume are 3.%—49%, 16.5—3. mg/g, 285—3.2 mg/g, 185—3.9 m2/g, and 0.112—0.224 m3.g, respectively. According to the experimental data, the multi-linear regression method was adopted to fit the relations between the characteristic parameters and influential factors. At final, through optimization method, the optimal adsorbent is obtained when using 62 min as hold time and 1105K as pyrolysis temperature. Under the conditions, the adsorbent was produced and compared the characteristic parameters with model forecast value, the coherence is satisfied.

关键词： adsorbent sewage sludge pyrolysis temperature hold time Doehlert’s matrix

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Optimal design study of high order FIR digital filters based on neural network algorithm

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Journal of Systems engineering and Electronics 2004年第2期15卷 115-119,130页

作者： Wang Xiaohua & He YigangCollege of Electrical and Information engineering, hunan university, changsha {3. P. R. china College of Electrical and Information engineering, changsha university of science and Technology,changsha 410077, P. R. china College of Electrical and Information engineering Hunan University Changsha 410082 P. R. China College of Electrical and Information engineering Changsha University of Science and Technology Changsha 410077 P. R. China

An optimal design approach of high order FIR digital filter is developed based on the algorithm of neural networks with cosine basis function . The main idea is to minimize the sum of the square errors between the amplitude response of the desired FIR filter and that of the designed by training the weights of neural networks, then obtains the impulse response of FIR digital filter . The convergence theorem of the neural networks algorithm is presented and proved, and the optimal design method is introduced by designing four kinds of FIR digital filters , i.e., low-pass, high-pass, bandpass , and band-stop FIR digital filter. The results of the amplitude responses show that attenuation in stop-bands is more than 60 dB with no ripple and pulse existing in pass-bands, and cutoff frequency of passband and stop-band is easily controlled precisely .The presented optimal design approach of high order FIR digital filter is significantly effective.

关键词： high order FIR digital filters amplitude-frequency response neural network convergence theorem optimal design.

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