28 June 2012, Volume 30 Issue 18

    

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Articles
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  Simulation of the Influence of Building Openings on Natural Ventilation Performance and Building Energy Consumption

  ZHOU Junli;TONG Baolong;ZHANG Quan;HU Yan

  . 2012, 30(18): 21-26. https://doi.org/10.3981/j.issn.1000-7857.2012.18.001

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  This paper analyzes the influence of building openings on the natural ventilation performance and the building energy consumption. The software Airpak and the building energy consumption simulation software DesignBuilder are used in the simulation. The influences of the building's orientation and the opening's position on the natural ventilation performance and the building's energy consumption are analyzed according to the Changsha typical meteorological data. A new evaluation index is proposed to compare the design schemes with consideration of the performance of the natural ventilation and the building's energy consumption. The optimal scheme combination of the building's orientation and the opening's position is obtained by the index.
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  The Numerical Character of Grid Coupling Ratio for the Immersed Boundary-Lattice Boltzmann Model

  LI Hanjun

  . 2012, 30(18): 27-31. https://doi.org/10.3981/j.issn.1000-7857.2012.18.002

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  In order to provide the foundation for immersed boundary points setting in the Immersed Boundary-Lattice Boltzmann Model (IB-LBM) frame, the numerical stability with the different Coupling Ratio of Grid (CRG) between the IB and LBM is studied. As the theoretical model to be verified for the applicable coupling ratio, flows around a circular cylinder with the Reynolds number of Re=40 and 100 are calculated, respectively. The distribution of streamline, the length of wake vortex, and the drag coefficient are analyzed for the case of Re=40 with the 4-point Piecewise Delta function being adopted in IB, the calculating results indicate that an acceptable range for CRG is 0.2-2, it is also essentially true for the case of Re=100. However, a different CRG range of 1.5—2 is found while the 4-point Cosine Delta function is used, the fact indicates that the 4-point Piecewise Delta function has a wider range for setting CRG, it is of great value to the optimal choices for Delta function and corresponding CRG in the IB applications.
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  Multi-mode Evolution Genetic Algorithm and Optimizaton of Thin-Walled Tube with Folding Patterns Baesd on Crashworthiness

  SUN Hailong;SUI Yunkang;YE Hongling

  . 2012, 30(18): 32-36. https://doi.org/10.3981/j.issn.1000-7857.2012.18.003

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  A multi-mode evolution genetic algorithm is proposed to improve the simple genetic algorithm and to solve the crashworthiness optimization design problems for a new type of thin-walled tube with folding patterns. Structural crashworthiness analysis is a highly non-linear transient dynamic process, involving a very complex relationship between the objective function (energy absorption value) and the design variables (wave height and angle) without an explicit function expression to optimize the design of the thin-walled tube. The optimization model of the thin-walled tube established by the Response Surface Method (RSM) and various encoder modes, the selection strategy, the crossover and the mutation operation are used in the multi-mode evolution improved genetic algorithm, and an inversion operation, similar to the genetic variation in the chromosome structure, effectively improves the population diversity. Examples of function test results show that the algorithm overcomes the local convergence of the GA and increases the convergent speed. The application of the multi-mode evolution genetic algorithm for crashworthiness optimization of the thin-walled tube with folding patterns shows the efficiency and convenience of this algorithm to solve such optimization problems. The energy absorption of the optimized structure is increased by more than 40% , a significant improvement over the initial design.
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  Shock Response of Buffer Platform for Equipment in Under-water Explosion

  ZHENG Changyun;ZHAO Pengyuan;ZHAO Hongguang;SONG Jingli

  . 2012, 30(18): 37-40. https://doi.org/10.3981/j.issn.1000-7857.2012.18.004

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  In the under-water explosion ship shock resistance test, the buffer platform is an effective tool for shock protection for the equipments. A small floating shock platform used as the test impact target, to test the buffering performance of the buffer platform under the explosion charge, with basic inputs of the buffer platform and the equipments on it being measured. The shock spectrum analysis method is used, to obtain the responses of the buffer platform. It is indicated that for the buffer platform, different damping ratios have a great influence on the platform equipment shock response; when the equipment has a large mass, the platform equipment response spectrum shows an apparent dip trend; in the equipment shock protection design, the effects of the mass of the equipment and the natural frequency on the shock spectrum should be considered, to reduce the design difficulty for the impact protection device.
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  The Control of Discrete-time Variable Structure Based on a Discrete Nonlinear Exponentially Approaching Law

  LU Qiang;BAI Hongrui;WANG Donglai;LIU Feng

  . 2012, 30(18): 41-44. https://doi.org/10.3981/j.issn.1000-7857.2012.18.005

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  A new discrete-time nonlinear exponentially approaching law is proposed to overcome the shortcomings of the traditional approaching law. A nonlinear function is adopted in the switching coefficients in the approaching law, to simulate the real situation that the distances of the switching coefficients from the system mobile point to the sliding surface decrease step by step, with the approaching speed improved and the chattering depressed, thus to improve the robust performance of the system indirectly. The simulation results show the superiority of the discrete-time approaching law, with better controlling performance for deterministic and non-deterministic systems alike.
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  System Design for Data Acquisition for Distributed Optical Fiber Vibration Sensing Signal

  ZHAO Xingqun;XUE Dongqing

  . 2012, 30(18): 45-49. https://doi.org/10.3981/j.issn.1000-7857.2012.18.006

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  According to the application requirement of a perimeter security warning system, a signal acquisition system for distributed optical fiber vibration sensing signal is designed in this paper, based on the embedded platform of ARM and FPGA. The data acquisition system uses FPGA as the main controller to achieve the dual-channel acquisition of the pulse wave and the continuous wave. FPGA receives control commands from ARM, and samples the digital signal converted by the sampling chips AD9430 and AD9203. Then the collected data is temporarily stored in the FIFO buffer generated by IP cores in FPGA, which will be transmitted to ARM. ARM is responsible for providing kinds of parameters for the data acquisition of FPGA and receiving data from FPGA. In this paper, the interconnection of the ARM processor and FPGA is presented, and the implementation of the FPGA driver in the embedded Linux is discussed. The data acquisition is implemented by FPGA,and the data transmission is realized with the ARM's external bus in this system. With the features of the low power consumption of ARM and the flexibility of FPGA, the signal acquisition system for distributed optical fiber vibration sensing signal is successfully applied in the monitoring system based on distributed optical fiber sensor.
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  Quantiative Analysis of Debris Flow Gully Based on Geomorphic Excess Entropy in Catchment

  ZOU Qiang;WANG Qing;LIU Yanguo

  . 2012, 30(18): 50-55. https://doi.org/10.3981/j.issn.1000-7857.2012.18.007

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  The activity evaluation of debris flow gully is the first step for forecasting, assessing, preventing, and controlling the debris flow. In order to resolve the problems, such as complexity of determination research, difficult of datum collection in the evaluation of debris brow gully, by virtue of GIS information processing technology, an effective and convenient method for quantitatively analyzing the evolution stage and activity degree of debris flow gully is discussed. In the method, a index of valley longitudinal profile shape is used to link the geomorphic system excess entropy with the evolution stage for debris flow gullies, also four ranks of activity for debris flow gully are divided into, they are: activity (-0.097≤δ_xP＜0,1.225≤N<2.0), sub-activity (-0.097≤δ_xP<-0.011, 0.585≤N<1.225), sub-stability (δ_xP≥0, N≥2.0), and stability (-0.011<δ_xP<0, 0<N<0.585). Furthermore, the method is applied to the middle reaches of Xianshui River along Sichuan-Tibet Highway and detail works are carried out. First of all, 58 catchments are extracted from 1:50000 local DEM with the support of GIS hydrologic analysis technology, and then the main lengths from 353m to 1712m and the areas from 0.47km2 to 58.09km2 of these gullies are acquired. After determining on the activity of debris flow gullies, some significant results are obtained as follows: 26 gullies accounting for 44.83% of total gullies are in the active period; 30 gullies accounting for 51.72% of total gullies are in the sub-active period and only two gullies are in the sub-stable phase. It is shown that the catchments located in the middle reaches of Xianshui River along Sichuan-Tibet Highway are in the developing and active evolution stage, and the activity degree of debris flow gullies is at a high level that is consistent with the actual situation. Based on the result, the method of geomorphic excess entropy analysis on the activity of debris flow catchments is objective, credible, easy to carry out for data scarce areas, and it is also helpful for evaluating, warning, and reducing debris flows.
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  Community Structure and Composition of Macro-soil-fauna in Apple Orchard in Summer

  LIU Changhai;QI Long;QU Yatan;YUAN Caixia;WANG Wenqiang;LI Yongchao

  . 2012, 30(18): 56-59. https://doi.org/10.3981/j.issn.1000-7857.2012.18.008

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  This paper studies the community diversity of the summer macro-soil-fauna in the apple orchard in Luochuan, to provide some basic material for the soil zoology in the non-timber forest in Northern region of Shaanxi. The macro-soil-fauna samples were acquired by a diagonal line five-point method of sampling and the universal hand-sorting, from the apple demonstration orchard and a conventional orchard in Luochuan in June, 2010. 134 individuals were collected, belonging to 9 orders, 6 classes, and 4 phylas. Among these sampled animals, the advantaged families were Enoplida, Lumbricidae, Coleoptera, and the familiar families were Diptera, Lepidoptera, Hymenoprera, and Syommatopora. The largest percent numbers of families were Enoplida, Lumbricida, Coleoptera, accounting for 78.57% of the total with each constituting 37.31%, 28.36%, and 12.69%, respectively, forming the main frame of the community. Besides, between the apple demonstration orchard and the conventional orchard, the macro-soil-fauna samples see an obvious surface aggregation. Compared with the conventional orchard, the demonstration orchard shows a higher group number, diversity, evenness and richness, but a smaller individual number and dominance. These data suggest that the soil-fauna in the demonstration orchard is rich in species, complicated in structure, and well-distributed in group number, which shows the response of the soil macro-fauna communities to the different land use types and management practices of the apple orchard.
Reviews
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  Research Progress and Technical Analysis of High Temperature Solar Thermochemical CO₂-splitting Cycle

  CHEN Wei;ZHANG Jun;

  . 2012, 30(18): 60-64. https://doi.org/10.3981/j.issn.1000-7857.2012.18.009

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  In the context of that global climate change has become an international hot issue, the CO₂ utilization through conversion of CO₂ into high value-added fuels is one of the possible ways to solve this problem. Combining this process with solar energy can contribute to solve the challenge which CO₂ is chemically inert and difficult to be converted into other molecules thermodynamically. Among a variety of approaches on converting CO₂ into energy carrier by solar energy, a promising new method for the production of synthetic fuel from solar-driven two-step CO₂-splitting thermochemical cycles is being developed. In this paper, we first described the research progress and research priorities in this field of some international research institutions. We also analyzed the technical principle and the basic research works need to be carried out in the future. The future research will focus on: (1) the fundamental analysis of radiation heat exchange coupled to the kinetics of heterogeneous thermochemical systems; (2) the design of advanced chemical reactor concepts based on the direct irradiation of reactants for efficient energy absorption; (3) the development of high-temperature materials (T>1500℃) for thermochemical reactors. Domestic research institutions which have the work foundation of high-temperature solar thermochemical utilization should pay more attention to this area and carry out related investigation. Their work will contribute to China's carbon emission reduction.
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  Contaminations and Remediation Technologies of Trichloroethylene and Perchloroethylene in the Soil and Groundwater: A Review

  ZHANG Fengjun;WANG Sijia;MA Hui;LV Cong;WANG Yubo

  . 2012, 30(18): 65-72. https://doi.org/10.3981/j.issn.1000-7857.2012.18.010

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  Due to their widespread use, unreasonable disposal, and their persistency in the subsurface environment, chlorinated ethenes have become one of the most commonly contaminants in groundwater and soils,. Since they are volatile, toxic, and carcinogenic, they have been widely concerned. Based on the literature review, the sources, hazards, and pollution of chlorinated ethenes are summarized. Furthermore, the remediation technologies of chlorinated ethenes, such as physical, biological, and chemical methods are concluded. Physical methods include aeration and activated carbon adsorption, chemical methods include chemical oxidation and chemical reduction, and biological methods include bioremediation and phytoremediation. Moreover, the development trends of TCE and PCE remediation technologies are looked ahead, and the microbial remediation, nano-metal particles, and photocatalytic oxidation technology are appreciated, and it is recommended that researches and applications of these three areas should be strengthened.
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  Summary on Logging Response Characteristics and Identification Methods for Shale Gas Reservoir

  XIAO Kun;ZOU Changchun;HUANG Zhaohui;NIE Xin;XIANG Biao

  . 2012, 30(18): 73-79. https://doi.org/10.3981/j.issn.1000-7857.2012.18.011

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  Shale gas is stored in the shale, and exists in the form of adsorbed and free state. Shale gas is becoming the hot spot of the oil and gas explorations. Geophysical logging technology has high vertical resolution and sensitivity, and is able to provide continuous petrophysical information along the borehole; therefore it is an indispensable means for the reservoir evaluation of shale gas. The geological characteristics and logging response characteristics of shale gas reservoirs are summarized, and identification methods of shale layers and shale reservoirs containing gas by well logging technology at home and abroad are discussed. In recognition of shale layers, the well logging method and cross plot method are introduced. In recognition of shale reservoirs, gas surveying method, conventional well logging combination method, ΔlogR method, and dielectric constant method are presented. According to the research, it is pointed out that combination well logging method and cross plot method could identify shale layers well, and gas surveying method, conventional well logging combination method, ΔlogR method, and dielectric constant method are able to obtain the good performance for identifying containing gas shale reservoirs. Shale gas reservoir logging evaluation research could provide the technical support for Chinese shale gas exploration and development. China should strengthen the research on shale gas reservoir logging evaluation technique and establish the suitable logging evaluation technology for China's deep shale reservoirs, which could reduce the risk of the shale gas exploration and development.