18 July 2014, Volume 32 Issue 20

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  • PAN Jinjun, JIANG Ying, GUO Peng, ZHANG Yongshan
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    Solar energy resource is the third renewable energy following hydropower and wind power. Europe remained the world's leading region in terms of its cumulative installed capacity, with more than 70 GW as of 2012, which represented about 70% of the world's cumulative PV capacity. Next in the ranking are China (8.3 GW) and the USA (7.8 GW), followed by Japan (6.9 GW). Since 2006, the annual growth rate of newly installed capacity of China has reached up to 200%-500%, far more than those of the other countries in the world. Based on a detailed analysis of the global and China PV industry development status, this paper studies the characteristics of solar resource reserves, China distribution and variation, as well as the environmental and meteorological factors influencing the utilization solar energy resources such as clouds, dust, fog and haze. There was a decreasing trend of reach the ground solar in China from 1961 to 1990, and an increasing trend from 1991 to 2000. The meteorological factors like clouds, dust, fog and haze may affect the situation of reach the ground solar. In China the total cloud and low cloud are less in the north and more in the south. The total cloud has shown a slightly decreasing trend and the low cloud a slightly increasing trend in China for the past 30 years. Sand and dust occur mainly in the Northwest China, and they have shown a significantly reduced trend. Fog and haze occur mainly in the local area of the Southeast China. Fog days have shown a significantly reduced trend, and haze a rapid increasing trend for the last 30 years. The different weather phenomena in different regions influence differently on the photovoltaic power generation efficiency. It is highly recommended that specific analysis should be done before establishment of any photovoltaic power station in order to better use resources and avoid unnecessary economic loss.
  • WU Yi, SUN Yinhang, LU Fang, HU Wenguang, LIAN Jie, YU Lei
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    The contact relationship between the Ejina Basin and the Badain Jaran Desert can be used to analyze the Ejina Basin groundwater level drops and the environmental degradation. By comparing local geological and geophysical methods of data analysis, the reasonable and effective audio magnetotelluric (AMT) geophysical methods are selected in the region to carry out original and innovative explorations, and a good result is achieved. Survey results suggest that the Ejina Basin is in rising, Badan Jaran Desert in declining, the lithology thinknesses on both sides see a great change, and the contact between the Ejina Basin and the Badna Jaran Desert is an extensional fault. The results can provide a basis for the analysis of the groundwater transforming relationship and, the Ejina Basin groundwater level declining in the studied area, and for the study of the groundwater formation mechanism in basin and desert, which is of important social significance for the recovery and the management of the ecological environment in the Ejina Basin.
  • ZHAO Su, KONG Deyu, YU Baoyang, TU Xu
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    Using the Liaohe-90# as the base asphalt, a modified asphalt mixture is prepared by the Buton rock asphalt. The pavement performance which includes high temperature stability, low temperature anti-cracking and water stability are studied through the rutting test, dynamic creep test, immersion Marshall test, freeze-thaw splitting test, small beam bending test and so on. The results show that with the increase of the admixture of Buton rock asphalt, the temperature sensing property and aging property of the asphalt can be improved effectively, and the high temperature stability and water stability modified mixture are enhanced. However, when the mixing amount of Buton rock asphalt increases from 20% to 30%, the low temperature performance is declined slightly. Therefore, the mixing amount of Buton rock should not be more than 30% in order to reduce cost and to use it in the northern area.
  • LI Xueren, ZHANG Zhuohang, DU Jun, CHANG Fei
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    Impact resistance of electronic chips has been a concern in the aeroplane industry. Based on dropping of the electronic chip on a specific device on the plane, this paper studies the impact resistance of the honeycomb structure of cushion rubber in electronic chips in devices on aeroplanes. Different honeycomb structures are adopted to study the relationship between the structure and impact resistance by using the finite element analysis software Abaqus. Different trepanning directions and sizes of the honeycomb are considered. The results show that the honeycomb structure improves the impact resistance of electronic chips compared with the solid ones, increasing the performance by 22%~33%. The impact resistance of longitudinal direction of trepanning is better than that of the transverse direction of trepanning, while the effect of trepanning size in this experiment is not apparent. The honeycomb structure can be easily manufactured, which means this study has engineering values.
  • WANG Xinmin, ZHU Yangya, JIANG Zhiliang, LIU Qi, WAN Xiaoheng
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    Based on the filling-slurry flowing law and final filling state in the stope, this paper analyzes the stability of filling materials with different roof-contacted filling ratios during the upward filling process. The process was divided into two parts: unlimited diffusion deposition and limited upward stacking. Combined with the final filling state, and beginning with 50% roof-contacted filling ratio, 11 filling models were built with an increasing gradient of 5%. The MIDAS/GTS finite element software was applied to analyze the stress condition of filling materials which had different roof-contacted filling ratios, and the comprehensive safety coefficient was put forward to evaluate the stability of filling materials, including the tensile coefficient, compressive safety coefficient and area size under concentrated stress. Take a specific stope as an example, when the roof-contacted filling ratio is under 75% in one-step route stope, the filling material still has the possibility of instability, although the tensile and compressive safety coefficients are higher than 1.0 and the comprehensive safety coefficient is under 1.0. When the roof-contacted filling ratio is above 75%, the tensile, compressive and comprehensive safety coefficients are higher than 1.0, the stability of the filling material reaches a safe level.
  • ZHAO Guoyan, SHEN Yanyuan, TANG Yang
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    The original water gushing data ineight tunnelsin Chinawere collected and classified.The prediction method of unascertained measurewas used to establish afeasible unascertained measurement model. There are many uncertain factors affecting tunnel water inflow, among which annual precipitation, geological and hydrogeological conditions, surface flow conditions and surface water supply conditionsare the most important ones, so they can be used as evaluation indices of the unascertained measurement model. Discrimination and analysis show that the accuracy of the discrimination method is high, which can be usedtoquickly distinguish categories of tunnel water gushing, providinga new way for tunnel water gushingdiscrimination.
  • HE Hujun, YANG Xingke, LIU Wei, LUO Yunzhi, FAN Yue
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    The significance of quantitative prediction of mineral resources and uncertainty evaluation was analyzed. Based on their uncertainty characteristics, uncertainty measure theory was introduced into quantitative prediction of mineral resources and uncertainty evaluation in this paper, and a prediction and evaluation model was proposed. Based on practical geological conditions, seven factors that influence the mineralizing favorability degree were taken into account and uncertainty measure function was established based on the in-situ data. The uncertainty problems in quantitative prediction of mineral resources and uncertainty evaluation were solved by qualitative analysis and quantitative analysis, respectively. Information entropy theory was used to calculate the index weight of factors, credible degree recognition criteria were used to judge the mineralizing favorability degree, and the order was arranged. This model was employed to evaluate three ore belts in Hutouya mine field in Qinghai. The results show that uncertainty measure method is reasonable and can provide reference for quantitative prediction of mineral resources and uncertainty evaluation in the future.
  • LUO Zhouquan, ZHANG Wenfen, XU Shimin
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    This paper studies data reduction of laser scanning to solve the problems generated by repeating of laser detection for blind areas. Blind areas of single detection were avoided and data of sparse areas were densified by multi-point detection. Distribution characteristics of point cloud data were concluded by topological relation of laser scanning track analysis. A more efficient point cloud data reduction method, the side angle integrated method, retained the geometric characteristics of goafs proposed in contrast to conventional data reduction, and the point cloud data of intensive areas were diluted. Through comparison of the 3D model volume, reduction rate and other indicators before and after reduction, the verification results show that the method ensures the integrity of boundary 3D information and the data reduction rate reaches 15%-25%. This method provides a new idea for laser scanning 3D information reduction in complex goafs, laying a good foundation for the subsequent 3D modeling and application.
  • DENG Hongwei, WU Yanlin
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    Groundwater interstitial flow is one of the major ways for the diffusion of heavy metal pollution. Based on the law of the convection, diffusion, and source-sink effect of groundwater flow, this paper analyzes the retardation effect of the curtain grouting project on the diffusion of heavy metal pollution, without considering biological degradation and chemical reactions. A onedimensional convection-diffusion simulation model of the transport process of contaminants and groundwater restoration model under disturbance of pumping wells were established using GMS software. The results showed that the curtain grouting project had apparent retardation effect on the diffusion and transport of heavy metal pollutants, reducing the diffusion radius. With continuous supply of pollutants in 365 d, the diffusion distance was shortened from 900 m to 465 m. The mass concentration of pollutants at the external observation site of the curtain project decreased from 2.8 mg/L to 1.42 mg/L, a reduction of about 50%. Under disturbance of pumping wells, the adsorption and dilution of pollutants in solidified and dissolved forms were accelerated in the project.
  • HUANG Rendong, LIU Kang, TONG Huixian, WANG Haifeng
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    Forrationally assessingthe stability of surrounding rocks,this paper adopts the following six factors, rock uniaxial compressive strengthRc, rock quality designation RQD, friction coefficient of the structural plane Jf, joint distance Jd, groundwater condition W, and integrity coefficient Kv, to classifythe stabilityof surrounding rocks into five levels after considering the advantages and disadvantages of existing assessment methods. In this paper, the weight of each factor is determined using the entropy weight theory, while the stability of surrounding rocks is calculated by the ideal point method through their closeness degree. This model is convenient for computer processing. Engineering application shows that the evaluation result is consistent with that of the BQ method, and it can better reflect the real state of rocksand provide scientific basis for engineering practice.
  • LEI Xiao, SUN Zhaobo, WANG Yanyan, LIU Shuangqi, WANG Shichao
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    Low-permeability unconsolidated reservoirs have a threshold pressure gradient to a certain extent due to low permeability. In addition, the reservoir rock shows medium to strong stress sensitivity because of the unconsolidated cementation, resulting in low oil flow velocity. Therefore, it is difficult to obtain sufficient information to make a reasonable interpretation. Water-injection well test is a good way to solve this problem. Based on analysis of the mobility ratio, the effects of stress sensitivity and threshold pressure gradient, a mathematical model for water-injection well test in low-permeability unconsolidated reservoirs was established. Since this model has strong nonlinearity, stable finite-difference scheme and Newton-Raphson iteration method were adopted to obtain the arithmetic solution. The pressure performance and influencing factors were also evaluated, and the typical well testing curves for analysis of real datawere plotted.
  • XIE Guanbao
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    Dual laterolog is a key to determine whether the stratum contains oil or not. However, due to impact of reservoir thickness, thin interbed oil reservoir, mud invasion and other factors, the discrimination capacity for oil and gas layers of the logging information is limited, bringing difficulties for oil and gas layer interpretation. Based on the electrical logging theory and fast forward numerical calculation method, this paper simulatesdual laterolog responseunder different reservoir conditions and analyzes its characteristics, revealing factors influencing the dual laterolog. On this basis, the inversion algorithm was used to carry out preprocessing of the dual laterolog data, calculatethe virgin zone resistivity, flushed zone resistivity and invasion radius, realizingthe environmental correction of dual lateral logging data. Applications show that this method can effectively eliminate environmental influenceon dual laterolog, and identify oil, gas and water layers with high accuracy, meeting engineering demand.
  • Reviews
  • WANG Rongshan, XU Chaoliang, HUANG Ping, LIU Xiangbing, CHEN Mingya
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    The mechanisms, simulation methods and mitigation measures of irradiation assisted stresscorrosion cracking (IASCC) in reactor internals stainless steels are discussed. The results indicate that the irradiation induced segregation, irradiation hardening and irradiation deformation are the mechanisms of IASCC, and the irradiation by charged particles, sensitized treatment and multi-scale simulation are the basic research methods. Based on the investigations of IASCC, the concentration control of chemical elements, microstructure changes, stress level control and water chemistry treatment are the main methods to mitigate IASCC.