18 April 2014, Volume 32 Issue 11

    

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  Inspiration Derived from the Aerospace Pioneers

  LU Yongxiang

  journal1. 2014, 32(11): 15-20. https://doi.org/10.3981/j.issn.1000-7857.2014.11.001

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  Konstantin Tsiolkovsky founded basics of astronautic theory, Robert H. Goddard created the world's first liquid-fueled rocket, W. von Braun developed rocket technology that helped land the first men on the moon, and the Wright brothers invented and built the world's first powered airplane and made the first human flight. This paper reviews the experiences of these great pioneers, which still inspire today's and future aerospace industry.
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  Effects of Tea Polyphenol EGCG on the Metabolism of Brown Adipose Tissue in Mice

  SHANG Yue, LI Yi, CHEN Shuzhen, ZHEN Yongsu

  journal1. 2014, 32(11): 21-25. https://doi.org/10.3981/j.issn.1000-7857.2014.11.002

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  With recognition of biological functions of brown adipose tissue (BAT) in adults, it has become a hot topic in medical research. In the present study, the effects of (-)-Epigallocatechin-3-gallate(EGCG) on the metabolism of BAT are investigated through animal experiments, histopathologicaland immunohistochemical methods. The results show that there are disparities in morphology of interscapular BAT among different species of mice. Vacuoles of fat droplets in adipocytes of C57BL/6 mice are the largest, and the cytoplasmic content is the least. Vacuoles in adipocytes of BALB/c mice are the smallest, and the cytoplasmic content is the most. Vacuoles and cytoplasmic content in Kunming mice lie between those in C57BL/6 and BALB/c mice. EGCG at 150 mg/kg decreases the increment rate of body weight and reduces the weights of epididymal white adipose tissue, but there is no statistical significance after different doses of EGCG are administered p.o. to Kunming mice. EGCG significantly decreases the content of fat (shown as vacuoles in the sections) in BAT and increases the cytoplasmic content (P<0.001). By immunohistochemical examination, EGCG increases the expression level of uncoupling protein 1, indicating the increase of energymetabolism in BAT. Therefore, there exist diversemorphological characteristics in different inbred lines of mice, which provides the basis for selection of mice in BAT studies. EGCG may regulate the metabolism of BAT in mice, which lays the foundation for further studies of its mechanism and provides new ideas for studies of the regulation of fat metabolism by tea.
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  Effects of Arbuscular Mycorrhiza on Growth of Amorpha Fruticosa L. and Soil Improvement in Coal Mining Subsidence Area

  WANG Jin, BI Yinli, DENG Mubiao, ZOU Hui, SUN Jiangtao, XIE Wenwu

  journal1. 2014, 32(11): 26-32. https://doi.org/10.3981/j.issn.1000-7857.2014.11.003

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  Arbuscular mycorrhizal technology is one of the important means for ecological restoration in mining areas. In this paper, effects of the arbuscular mycorrhizal (AM) inoculation on the growth and development of Amorpha Fruticosa L. and soil quality were studied between 2 and 14 months post-inoculation. The results showed that compared with that of the non-inoculated Amorpha Fruticosa L., the survival rate of inoculated one increased by 7.2%-9.7%, the plant height markably increased by 34%-62%, the crown diameter significantly increased by 39%-65%, the mycorrhizal infection rate significantly increased by 16%-21%, and the hyphal density increased by 50%-70%. The mycorrhizal infection rate and hyphal density had significantly or highly significantly positive correlations with contents of organic carbon, total nitrogen, available phosphorus and potassium, alkali-hydrolyzable nitrogen in the soil. The soil pH significantly decreased, and the contents of soil organic carbon, total nitrogen, available phosphorus and potassium, alkali-hydrolyzable nitrogen significantly increased by the inoculation of mycorrhiza. Glomalin related soil protein is an important composition of organic matter in soil, which can reflect small changes of soil quality. These results show that AM can promote growth and development of Amorpha Fruticosa L. and soil improvement in coal mining subsidence areas.
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  Screening and Identification of an Aerobic Denitrifying Bacterium with Low C/N Ratio at Low Temperature

  ZHOU Lanying, MA Xiulan, ZHANG Chendong, WANG Chengyu, ZHANG Fengjun

  journal1. 2014, 32(11): 33-37. https://doi.org/10.3981/j.issn.1000-7857.2014.11.004

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  The conventional denitrification process has limited applications due to its disadvantages, such as long generation time of denitrifying bacteria, especially in cold winter, long hydraulic retention time and high costs. In this study, an aerobic denitrifying bacterium designated as HFX08 was isolated from a domestic sewage plant in a northern city of China in winter. The strain HFX08 exhibited high denitrification performance under low C/N ratio at low temperature. The results indicated that the strain HFX08 was G^- and identified as Pseudomonas sp. The optimum temperature for its growth is in the range of 10-20℃. Its growth curve was fitted to S growth curve, whose fitting coefficient reached the level of extremely significant difference. The nitrogen removal rate by strain HFX08 increased with increasing C/N ratio, up to 92%.
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  Preparation of High Strength Structural Materials Using Iron Ore Tailings Based on Uniform Design

  WU Hui, NI Wen, TANG Chang, CHEN Xingjie, QIU Xiajie

  journal1. 2014, 32(11): 38-42. https://doi.org/10.3981/j.issn.1000-7857.2014.11.005

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  High strength cementitious materials are usually prepared using iron ore tailings by step-milling method. For optimal stepmilling, this paper studies its effect on mechanical properties of the high strength structural materials based on uniform design. Stepwise regression analysis in SPSS software was used to establish the regression equation, which takes the strength of concrete as the objective function, and the optimum milled program for preparation of the high strength structural materials was obtained by the optimization technology in the Matlab software. The result of the experiment shows that the high strength structural material was successfully prepared when the milling time of each stage in the step-milling was set to be 21, 67 and 57 min and the specific surface areas were 285, 485and 550 m²/kg. Its compressive strength reached 75.28 MPa. The optimization of the step-milling method shows that the micro-ball effects play an important role in preparation of the cementitious materials.
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  Analysis of Social Ties and Checkins in Location-based Social Networks

  LIANG Xiao, ZHAO Jichang, XU Ke

  journal1. 2014, 32(11): 43-48. https://doi.org/10.3981/j.issn.1000-7857.2014.11.006

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  Understanding the relationship between friendship and mobility is crucial to studying the evolution of social networks and modeling human movements. This paper aims to quantify the correlation between social ties and checkins by investigating two location-based social networking websites. It is discovered that the probability of social or checkin’s rank is inversely proportional to the corresponding rank, which implies the potential connection between friendship and mobility. Therefore, the fractions of friends and checkins in the same county at different scales are compared and the Pearson correlation coefficients of users are computed. These results all demonstrate that social friendship correlates closely with human movements.
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  Reactive Power Compensation Based on Radial Basis Function Neural Network for Wind Farm Connected to Power System

  ZHANG Hongtao, ZHANG Lingyun, LI Xiaodan, QIU Daoyin

  journal1. 2014, 32(11): 49-54. https://doi.org/10.3981/j.issn.1000-7857.2014.11.007

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  This paper proposes an optimization algorithm based on radial basis function (RBF) neural network to deal with heavy workload and complex calculation process of wind farm reactive power capacity calculation. First, a model for power flow computation of power systems containing wind farm is established, and the actual active power of a wind farm is taken as the input of the model, to calculate the reactive compensation capacity required. Second, the actual active power of the wind farm is used as input data, and the resulting reactive power compensation capacity as the target output, to establish a RBF neural network and train it. Finally, with the trained RBF neural network replacing the power flow calculation model, the reactive power compensation capacity for the wind farm is calculated. Calculation results show that the computational complexity of RBF neural network model is lower than that of the power flow calculation model, and the workload is reduced. Thus, the RBF neural network model can be trained to replace the power flow calculation model to calculate the reactive power compensation capacity of wind farm in real time.
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  Evaluation of Water Inrush from Floor Containing Insidious Fault Based on Crack Growth

  HU Xinyu, WANG Lianguo, LU Yinlong, YU Mei

  journal1. 2014, 32(11): 55-59. https://doi.org/10.3981/j.issn.1000-7857.2014.11.008

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  For analyzing the security of floor containing insidious fault while mining above water, a fracture mechanical model is established in order to describe the activation and growth of insidious fault. First, from the beginning of aquifer top in floor, the above part of insidious fault is modeled as an oblique edge crack of finite width plate. Second, involving the effects of normal stress and shear stress for fault activation, effective shear stress distribution in the fault plane is calculated in the mining conditions. Third, according to attitude and burial depth in the floor of fault, distance of face advancing, water pressure of the aquifer, and angle of friction in the fault plane, the compress-shearing stress intensity factor of insidious fault is presented. Finally, the safety index is defined for establishing the criterion of water inrush. Taking a certain coal face mining under pressure for example, in accordance with its hydrologic and geological data, variation of risk about water inrush from activating fault is obtained during the whole face advancing across the fault. The conclusion coincides with microseismic monitoring data at the site. This analysis may provide suggestions for safe and rational coal mining and improve numerical or theoretical models of water inrush in floor.
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  Parallel Section Method of 3D Geological Space Visualized Dynamic Estimation

  WANG Liguan, ZHU Liqing, PENG Pingan, LIU Yanhong

  journal1. 2014, 32(11): 60-65. https://doi.org/10.3981/j.issn.1000-7857.2014.11.009

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  The traditional mineral resource estimation method has the advantages of simple operation for the geological staff. But, it is weak in the mineral resource estimation, lacking a three-dimensional sense, and with a low estimation accuracy. However, the geostatistics is difficult to adapt to the ore deposit mineral with the characteristics of different kinds of mineral species，the complex type and a variety of forms in our country. This paper puts forward a new idea: based on the method of the parallel section, the real three-dimensional model instead of the simple and abstract two-dimensional ones is dealt with by using the 3D mining software, which achieves the mode of the ore volume acquisition in the real three-dimensional environment. The results of applications to some mines show that the parallel section method of 3D geological space effectively improves the reserve estimation model, which, to some extent, enhances the visibility and achieves the purpose of the high precision of ore body reserves.
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  Influence of Grid Subdivision on the Resistivity Curve

  ZHU Chongli, DONG Shuqian, ZHOU Diangang

  journal1. 2014, 32(11): 66-70. https://doi.org/10.3981/j.issn.1000-7857.2014.11.010

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  As a highly efficient numerical simulation method, finite element method is widely used in geophysical forward calculation. Whether grid subdivision is suitable or not is the prerequisite for finite element solution. From the aspect of ideal twodimensional medium model, this paper discusses the effect of grid subdivision on magnetotelluric forward modeling precision, under the conditions that the subdivision areas have the same size, the boundary conditions are satisfied, and the sparse and dense mesh are compared. In low frequency phase, two polarization modes were taken as a whole, the coarse grid has higher simulation accuracy than the fine grid, but at the beginning of the near-surface phase under TM mode, the simulation accuracy of the coarse grid is not as high as that of the fine grid. Overall, the coarse grid has more moderate change than the fine grid, and the fluctuation amplitude of the coarse grid and fine grid is higher in the tail of the curve, both of which deviate from the normal value. The results show that proper grid subdivision can effectively improve the accuracy of electromagnetic finite element forward modeling, and it is significant for the subsequent inversion as well.
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  Threshold Standards in Heavy Oil Reservoir Exploitation Using Steam Assisted Gravity Drainage with Dual-horizontal Wells

  MOU Zhenbao, TANG Shuai

  journal1. 2014, 32(11): 71-76. https://doi.org/10.3981/j.issn.1000-7857.2014.11.011

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  Steam assisted gravity drainage (SAGD) is an advanced technology for the exploitation of super heavy oil reservoir, possessing high oil displacement efficiency and high recovery ratio. The reservoir exploitation threshold standards of SAGD depend on the combined effect of reservoir parameters, technological conditions and oil prize. Other countries have given the SAGD reservoir exploitation threshold according to their own reservoir thickness, oil viscosity and exploitation conditions, but there is no reasonable threshold standards for China to conduct SAGD deployment and efficient exploitation under different reservoir conditions. In this paper, the effect of key reservoir parameters on SAGD exploitation is studied using reservoir numerical simulation technologies. On that basis, the main controlling factors of reservoir exploitation effect in terms of net profit using SAGD with dual-horizontal wells is determined through orthogonal design and multi-index analysis. Finally, the threshold standards of reservoir exploitation using SAGD under different crude oil prices are obtained under existing technological conditions.
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  Comparison of Evaluation Systems for Development of Infrastructures for Science Popularization in China

  CHEN Keke, REN Fujun, LI Zhaohui

  journal1. 2014, 32(11): 77-83. https://doi.org/10.3981/j.issn.1000-7857.2014.11.012

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  The primary purpose of this paper is to analyze how the evaluation system for the development of infrastructures for science popularization was built in 2008 and why and how it was improved in 2012. The method used in our study is documentation, quantitative analysis, expert interview and summarization. The analysis strongly suggests that in today's China, it is necessary to build an evaluation system to measure the development of infrastructures for science popularization, enabling researchers to provide good advice to the government in policy-making concerning science popularization. It is concluded that the evaluation system has its academic value and works quite well. Furthermore, the development of the system needs to keep pace with changes of the social environment.