18 December 2012, Volume 30 Issue 36

    

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  Mechanism and Process of Anaerobic Sludge Granulation in UASB Reactor with Aerobic Activated Sludge as Seed

  LI Jianzheng;ZHANG Liguo;BAN Qiaoying;XU Yiping;AI Binling

  . 2012, 30(36): 19-23. https://doi.org/10.3981/j.issn.1000-7857.2012.36.001

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  The mechanism and the process of the anaerobic sludge granulation of the aerobic flocculent sludge in an Upflow Anaerobic Sludge Blanket (UASB) reactor are studied in this paper. The sludge is obtained from a secondary sedimentation tank of an activated sludge plant for treating municipal wastewater. The results show that the anaerobic granular sludge is cultivated successfully after the continuous operation for 150 d and the Hydraulic Retention Time (HRT) is reduced from 24 h to 8 h. During the phase-shortening, the sludge load and the hydraulic load are increased from 0.25 kg COD/(kg(VSS)·d) and 0.1 m³/(m²·h) to 0.52kg COD/(kg(VSS)·d) and 0.3m³/(m²·h), respectively. The process of the granulation contains five stages, including the sludge acclimation, the microbial aggregates formation, the primary granular sludge formation, the secondary granular sludge formation and the mature granular sludge formation. During the mature granular sludge formation stage, the COD is removed approximately by 95%. The mechanism of the anaerobic sludge granulation of the aerobic flocculent sludge is consistent with the second nuclei theory as a whole. The primary granular sludge formation mechanism is consistent with the Extracellular Polymers (ECP) theory, while the secondary granular sludge formation mechanism is consistent with other reported theories. In this study, the secondary granular sludge is formed by the methane filamentous bacteria and other bacteria inserting or absorbing to the fragments while its inner nuclei are composed of primary granular broken fragments.
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  Feature Extraction and Classification of Fiber Signal in Security-Monitoring System

  WAN Suiren;PENG Licheng

  . 2012, 30(36): 24-28. https://doi.org/10.3981/j.issn.1000-7857.2012.36.002

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  The discrimination between the intrusion and the nuisance events without compromising sensitivity is a key performance parameter for any outdoor perimeter intrusion detection system. In certain circumstances, the signals of the intrusion and the nuisance events are almost the same. This is especially the case for the intrusion and the nuisance events which may have a similar impact. In this paper, a series of methods are proposed to extract the fiber-signals: to denoise the input signal based on the wavelet transform; with a new practical algorithm of pre-segmentation of the fiber-signal, based on the hypothesis that the distribution of the energy of the intrusion in the time domain is different from that of the nuisance; to generate the eigenvector extracted from the distribution of the energy in the wavelet space; and to classify the fiber-signal using the support vector machine. With the assumption that different kinds of fiber-signals have different energy distributions in each frequency, the results of this experiment are satisfactory. This method is practical because we may take advantages of the SVM with very small cost.
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  A Numerical Boundary Scheme of OCS4 and Its Asymptotic Stability

  LIU Xiao;LI Yifan;LI Wenqiang;WANG Zhenhua

  . 2012, 30(36): 29-33. https://doi.org/10.3981/j.issn.1000-7857.2012.36.003

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  Based on the ideas of the polynomial fitting numerical boundary scheme (SFEBS) and the Taylor expansion boundary scheme (TEBS), a fourth-order numerical boundary scheme (SF-TEBS4) is proposed in this paper. The SF-TEBS4 is an extension of the optimized fourth-order staggered tridiagonal compact difference scheme (OCS4) and the corresponding interpolation scheme (OCI4) on the staggered grid system, developed by the authors recently, for the equations with non-periodical physical boundary conditions. The asymptotic stability of the overall difference scheme, the combination of the numerical boundary scheme SF-TEBS4, and the inner points schemes OCS4 and OCI4, is analyzed. It is shown that, SF-TEBS4 combined with OCS4 and OCI4, can achieve the asymptotic stability. Moreover, the numerical experiment for determining the first order derivative of a function indicates that (1) the global accuracy of our scheme is fourth-order, and that (2) the computational error is reduced greatly. The numerical experiment for solving the wave propagation problem shows that the combination of SF-TEBS4 with OCS4 and OCI4 can effectively suppress the growth rate of the computational error, preserve the group velocity and the numerical asymptotic stability. The theoretical and numerical analyses show that the combination of SF-TEBS4 with OCS4 and OCI4 can be applied to simulate the propagation of small scale waves.
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  The Design of Multi-function Underwater Acoustic Signal Generator and Data Acquisition Display Control System

  ZHAO Shan;SUN Changyu;YU Huabing;CHEN Xinhua

  . 2012, 30(36): 34-37. https://doi.org/10.3981/j.issn.1000-7857.2012.36.004

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  In view of underwater acoustic complex signal and expensive data acquisition card, based on sound card acquisition and virtual instrument technology, a multi-function underwater acoustic signal generator and data acquisition display control system generator method are proposed. And the sound card and NI-DAQ devices are used to realize multi-function underwater acoustic signal control, transmission, display and audio signal acquisition, display based on the platform of LabVIEW. The system not only could be used as a virtual signal source for generating the desired signal used by underwater acoustic transmitter, but also the sound card could be used to acquire and measure audio analog signal, then display the signal in real time. The emission signal generated by the system is acted on an underwater acoustic power amplifier and practical applications are combined with for the purpose of laboratory validation. Results indicate that the system is able to effectively generate and control the actual signal needed. The module design for both control output and gathering input has high degree of integration, versatility; the hardware cost is reduced. The system possesses the advantage over friendly interface, low cost, and simple operation for spreading.
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  Design of the Communication Software for Logging Tool Test-bench Based on C/S Model

  YANG Xifeng;JU Xiaodong;WU Wenhe

  . 2012, 30(36): 38-41. https://doi.org/10.3981/j.issn.1000-7857.2012.36.005

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  According to the demand of the micro-resistivity scanning tool test-bench, this paper proposes a design scheme of the test-bench communication interface program based on the C/S mode. From a comparison of the characteristics between the B/S and C/S communication modes and the flow and data report type sockets, the paper chooses the flow socket C/S mode as the mode of the communication interface. In order to solve the blocking problem of simple flow sockets, in the front-end computer, the multithreading technology is introduced to realize the independent communication process. In order to improve the interface scalability and portability, in the PC program, the Winsock control is used to realize the communication function. It is shown by performance tests that the communication interface has a good stability and speed. The interface enjoys features of simple structure, excellent performance and good portability, and can be directly applied in the test-bench and the testing system of similar structures.
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  Productivity Analysis for Acid Fracturing Well with Consideration of the Effect of Acid Wormholing Zone and Variable Gas PVT Parameter

  XIONG Jian;FENG Yanli;ZHANG Nan

  . 2012, 30(36): 42-46. https://doi.org/10.3981/j.issn.1000-7857.2012.36.006

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  In view of the variations of the PVT parameters in the acid wormholing zone and the gas with the pressure, based on the change of the fluid flow pattern after fracturing, using the steady seepage theory, with the consideration of the influence of the start-up pressure gradient, the slippage effect and the stress sensitivity in the low-permeability gas reservoirs, a gas well productivity prediction model is established for the finite conductivity vertical acid fracture wells. The influence of some factors on the productivity is analyzed by using examples. It is shown that the gas PVT behavior has a great influence on the gas well production in the low flowing pressure stage, but has little influence on the gas well production in the high flowing pressure stage. With the consideration of the variation of the gas PVT behavior and the gas PVT invariable behavior, the start-up pressure gradient, the stress sensitivity and the slippage effect have similar influences on the gas well productivity, but their working mechanisms are different. The longer the length of the acidizing wormhole is in the acid wormholing zone, the more the extent of the gas well productivity is decreased. The more the permeability is in the acid wormholing zone, the lesser the decreasing extent of the gas well productivity.
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  CO₂ Corrosion Law and Its Application to Analysis of Tubing in Deep and Super Deep Wells

  ZHANG Chunyan;QIAN Wenhui;ZHENG Yuping;HU Lixin;LIU Xuefeng

  . 2012, 30(36): 47-51. https://doi.org/10.3981/j.issn.1000-7857.2012.36.007

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  The corrosion rate and characteristics of several kinds materials are studied under the in situ conditions of high pressure and high temperature in the stirring aqueous solution in a nickel-based alloy autoclave. The test results show that the corrosion rate and characteristics under different well conditions are different, the highest corrosion rate is 5 times greater than the lowest one. And in the same well, the corrosion rates of different materials and sections of a well are also different under the simulating test conditions. The differences come from the joint effects of multi-factors in different degrees. In different sections of a well, different corrosion characteristics of the same material are observed. As can be seen from the topography of the corrosion scales, the binding force of the corrosion scales with the base metal and the corrosion rate itself, the most serious corrosive section is at a depth from 1500m to 3500m, with the top 1500m part slightly corroded. At the bottom of the well, the corrosion is also gentle according to the formation of corrosion scales and the excellent binding force which would obstruct the corrosion process. Therefore, many factors should be considered when studying the CO₂ corrosion characteristics of tubing materials in deep or super deep wells, such as the tendency of the corrosion rate, and the conditions of the well. The temperature, the pressure and the flow rate of each well in different sections should also be tested and calculated to find out the most serious section under the corrosion, conditions and the effects of different factors are not the same on the corrosion rate. Therefore, the joint effects of all factors should be considered when studying the CO₂ corrosion of tubing.
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  Numerical Simulation of Blasting Failure Mode of Jointed Rock Mass

  LIU Hongyan;ZHANG Jihong;

  . 2012, 30(36): 52-55. https://doi.org/10.3981/j.issn.1000-7857.2012.36.008

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  The finite element method and the discrete element method widely used in practice can not adequately deal with lots of intermittent joints, the fragmentation of rock mass and the rock block movement. Therefore, a new numerical method, the numerical manifold method, is developed for that purpose. In the numerical manifold method, the mathematical mesh and the physical mesh are used to form a manifold element, which can very easily be used to deal with the lots of original joints in the rock mass. Meanwhile, the fracture mechanics principle is used to simulate the propagation of the joint and the crack, and the block movement theory in DDA is used to simulate the block movement. Finally, a calculation example is taken to analyze the difference of failure modes between the intact and jointed rock masses, and the results show that the existence of joints would greatly affect the rock mass blasting failure mode, and its effect is closely related to the joint's geometry distribution and physical and mechanical properties.
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  The Ecological Reclamation Effect of Arbuscualr Mycorrhizal Inoculum on Subsided Land in the Area of Shendong Coal Mine

  YUE Hui;BI Yinli;ZHAKYPBEK Y.;JIANG Mingming;GAO Fei

  . 2012, 30(36): 56-60. https://doi.org/10.3981/j.issn.1000-7857.2012.36.009

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  Currently, arbuscular mycorrhizal fungi technology becomes one of the hotspots in the research on land microbial remediation for mining subsidence. Taking amorpha fruiticosa planting in the mining subsidence of Shendong mining area as a study object, AMF vaccinated on amorpha fruiticosa after 16 months, 25 months, and 28 months, respectively are used to analyze its effect on the growth of plant and on rhizosphere soil physical properties. And then the correlation between hyphae density and effective phosphorus of rhizosphere is analyzed. By using regression analysis, it is indicated that in different monitoring time, for example, hyphae density and effective phosphorus in September had better linear fitting than that in June, which is closely associated with development time of mycorrhizal. With the time passing by, the correlation of vaccination between hyphae density and effective phosphorus content is gradually decreased; however, the positive correlation of un-vaccinated is gradually emerged. The results of mycorrhizal bioremediation on mining subsidence in Shendong mining area prove that vaccination not only could effectively promote growth and development of amorpha fruiticosa in macroscopic, but also could improve the growth matrix conditions in microscopic.
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  The Matured and Removed Syndrome Characteristics Criteria of Abnormal Hilit for Abnormal Savda Type Tumor with Uighur Medicine Based on Delphi Method

  UPUR Hamulati;ABODULAIHAITI Wuerguli;MAITISIDIKE Ayinuer

  . 2012, 30(36): 61-65. https://doi.org/10.3981/j.issn.1000-7857.2012.36.010

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  Two-stage expert consulting research is conducted in order to set up diagnostic criteria for abnormal hilit matured and removed from body with abnormal savda type tumor with traditional Uighur medicine based on Delphi method. At the first stage, an enquiry form including key syndrome characteristics which were identified by the past research results from our research group is formulated, and then sent to 30 experts who are located in the Xinjiang Uygur Autonomous Region and have rich experience in this field. Round one Delphi technique is conducted at this stage. Then 10 kinds of syndrome characteristics, such as sleeping increasing, doing more dream, nightmare reducing, mental color gradually improving, and having a pair of sparkling eyes are selected as diagnostic criteria for abnormal hilit matured from body with abnormal savda type tumor. And eight kinds of syndrome characteristics, such as mental color significantly improving, moderative mood, sleeping quality significantly improving, tongue fur is damp and closes to the original state, are selected as diagnostic criteria for abnormal hilit removed from body with abnormal savda type tumor in accordance to expert high consensus that frequency is greater than 70% (21 out of 30 experts). At the second stage, a new enquiry form based on screening results of the first stage is formulated, and the weight coefficients of each selected syndrome characteristics are studied, Round two Delphi technique is conducted at this stage and 30 copies of valid questionnaire are responded for each round. Expert authority coefficient is 0.825 on average and is considered to be high authority degree. By analyzing the weight coefficients of each selected syndrome characteristics, five kinds of syndrome characteristics are considered as major symptoms and other five kinds of syndrome characteristics are considered as subsequent symptoms for diagnosing abnormal savda type tumor abnormal hilit already matured or not. Four kinds of major symptoms and other four kinds of subsequent symptoms are selected for diagnosing abnormal savda type tumor abnormal hilit already removed from body or not. Both expert concentration and coordinate degrees are high. The consistency coefficients for abnormal savda type tumor abnormal hilit matured syndrome criteria are (χ²=0.261, P=0.000) and two around are same, for diagnostic criteria for abnormal savda hilit removed from body is (χ²=0.248, P=0.000), and two around are also same. The establishment of diagnostic criteria for abnormal hilit matured and removed from body with abnormal savda type tumor with traditional Uighur medicine based on modified Delphi method would provide an objective and quantitative basis for the effective, standardized diagnosis and treatment of the tumor.
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  Evaluation Methods for Forecast Accuracy of Wind Speed and Wind Power of a Wind Farm

  JIANG Ying;LI Zhong;HOU Youhua;ZHAO Dong;

  . 2012, 30(36): 66-71. https://doi.org/10.3981/j.issn.1000-7857.2012.36.011

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  The accurate evaluation of the wind speed and wind power forecast for a wind farm can effectively promote the forecasting accurate levels and reduce the adverse effects of the wind power on the power network. This paper makes a comprehensive review of forecast accuracy evaluation methods of the wind speed and the wind power for wind farms, and it is shown that the forecast accuracy evaluation methods fall into four categories, the common mathematical prediction accuracy evaluation method, the forecast error percentage method relative to the wind farm rating, the grade forecast accuracy evaluation method and the method closely integrated with the wind power generation characteristics. These accuracy evaluation methods are analyzed with respect to the characteristics, the extent and the scope, related with the wind power generation characteristics.