18 June 2012, Volume 30 Issue 17

  • Select all
  • LI Sanguo;XIE Guanbao
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    In the current mud logging gas measurement technology, the hydrocarbon gas mainly comes from the electric degasser, which churns up the drilling fluid to separate the hydrocarbon gas, and to get C1—C5 gaseous hydrocarbon components. The content of the hydrocarbon gas detected by this way is, on the one hand, affected by the drilling fluid, and on the other hand, due to the uncertainty of the air content, the oil and gas display is only evaluated qualitatively. The semi-permeable membrane can separate selectively the hydrocarbon components, and can be directly inserted into the drilling fluid to separate the oil and gas, and thus the hydrocarbon components of the gas and liquid can be obtained at a normal temperature. This method enjoys a number of advantages, such as, it is less affected by the drilling fluid, and it may provide a quantitative evaluation of the oil and gas content. Therefore, in order to evaluate quantitatively the hydrocarbon gas sources in the mud logging gas measurement technology, a proper semi-permeable membrane and the related apparatus for the oil and gas separation are developed. The parameters, such as the response time, the degassing efficiency, the gas attenuation, and the response characteristic of C1—C8 (including benzene and toluene) are studied. It is shown that the oil and gas can be detected while drilling at the well site, with a richer information about the content of the hydrocarbon detection and the hydrocarbon reservoir evaluation.
  • ZHENG Zhiwei;WU Changchun
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    The end section storage is an important mean for short term peak shaving of gas pipeline. Steady state calculation is usually adopted to estimate end section inventory, however the process of end section storage is a complicated dynamic process, and the end section inventory obtained by steady state calculation has some deviation. The deviation range of steady state calculation is defined via dynamic simulations on end section storage in many conditions. And some patterns involving end section storage are obtained. According to the factors which affect end section storage of gas pipelines, six conditions which have different inner diameters, lengths, inlet pressures, and flow rates of end section are simulated by using an internationally popular pipeline simulation software of Stoner Pipeline Simular (SPS) 9.6. The simulation results indicate that with dynamic conditions, end section inventory obtained by steady state calculation is about 14%—25% less than that by dynamic calculation. The change of end section inventory is affected by the change pattern of end point gas load, the largest end section inventory occurs nether before the largest end point gas load or more or less at the same time. When the end point flow rate changes, end section inlet pressure changes after outlet pressure. The longer end section is, and the larger inner diameter is, the more obvious hysteresis is.
  • ZHANG Junfeng;FU Yingqian;NIU Bin;MU Dan
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    Before carrying on a reasonable exploitation of coal bed methane, it is necessary to take the inverse computation for the parameters of coal bed by well testing analysis. The method of injection/falloff is the most commonly used in coal bed methane well testing. In order to expend the applications of the injection/falloff method in well testing and to gain more information about the coal bed, the injection/falloff well testing process is reconstructed in terms of an experimental system designed in the laboratory. The change of pressure on well bottom is obtained by controlling injection flux. It is indicated that the experimental result is consistent with the in-situ result. The method of multi-level injection is presented in the simulated experimental study to gain more information involving the pressure change on well bottom at different stages. The results show that the pressure on well bottom is nonlinearly increasing with the increase of injection flux. By controlling the injection flux, the simulated experimental process is able to sufficiently response the pressure change on well bottom, and to obtain more digital information about well bottom for further well testing interpretation. In the meanwhile, this kind of experiments could be carried out to verify the rationality and accuracy of the proposed model for theoretical interpretation by controlling and changing the given parameters of well bottom.
  • XIAO Yanwen;WANG Xiangdong;WU Fengxian;YU Qingbo;WANG Haifu
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    A calculation model based on the cavity expansion theory is developed to predict the overloading on the truncated-conical projectile penetrating into finite thickness metallic plates at low speed. The influences of the velocity of the projectile, the projectile taper and the strength of the target material on the overloading are analyzed. The results show that the velocity of the projectile has a noticeable effect on the magnitude of overloading but a much less important effect on the period of the overloading; both the projectile taper and the strength of the target material have a significant effect on the magnitude and the period of the overloading, the magnitude and the period decrease as the taper and the velocity decrease. The predicted results are in good agreement with experimental results, which has validated the model.
  • ZHANG Jiamin;FU Jindan;LIU Hao
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    The slopes of mountain spoil field located at the Zhengjiaya tunnel of the Yiba highway are taken as an example. The improved orthogonal analysis method based on the grey theory is introduced and then the numerical simulation software of Flac3d is used to analyze the sensitive factors which affect the stability of the mountain spoil field slopes. The result shows that strength parameters of the soil and the free surface shape are the highly significant influence factors which affect the stability of the mountain spoil field slopes in these areas. And the unit weight and slope rate have less influence on the stability of mountain spoil field slopes. The result is consistent with that of the gray method and the principal component analysis method. Therefore the results obtained from the improved orthogonal method are considered reliable.
  • CHEN Jianhong;WU Shuliang;YANG Shan
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    With the complexity of the underground metal geological and mining conditions, the influencing factors of the rock displacement are an complicated issue and they are interactive, which leads to the great uncertainty of the prediction of the rock displacement. Large amounts of sample data slow down the training process of the neural network, which makes the neural network instable. The PCA (Principal Component Analysis) is, therefore, used, combined with the Elman network, to build the model for prediction of the underground mining rock displacement angle. The principal component analysis is used in the raw data pre-processing to extract the main ingredients from the original information, to reduce the amount of input data and make them unrelated, thus to speed up the neural network training process; the samples are then trained with the Elman network, and with the trained network to make predictions for the samples. Compared with the predicted results obtained without using the PCA, the predicted results obtained by using the PCA are more accurate. Through comparing the expected output with the actual output, the relative errors are less than 5%, which shows that the PCA combined with the Elman network is good for the prediction of the underground mining rock displacement.
  • TANG Xiaqing;CHENG Xuwei;ZHANG Huan;XU Zan
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    In order to compensate for the errors of Fiber Optic Gyroscope (FOG) in an attitude measurement system, according to dynamic and static error distributions of FOG in the time and frequency domains, the basic methods of wavelet, analyses are introduced and how to select threshold and threshold function is compared. The algorithm for real-time wavelet threshold filtering with moving window is adopted to de-noise output signals of FOG. Experimental results show the feasibility of the real time wavelet threshold method in FOG signals de-noising. The real-time wavelet de-noising algorithm with combination of soft and hard thresholds has the advantages over single algorithm, the algorithm is able to not only improve the precision and stability of the FOG, but also provide reference value for dealing with the FOG signals.
  • LI Tao;ZHANG Jingzhong
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    The continual induction for the real number is very similar to the mathematical induction for the natural number, the induction is equivalent to the Dedekind axiom, and could be widely used in the calculus research. Firstly, a novel proof for the continual induction is presented; the proof is more acceptable than the former. And then, some discussions on its applications are made, it gives some meaningful advices to the higher mathematics teaching. The continual induction could also be used in the mechanization research on analytical reasoning.
  • ZHENG Yuanpan;SU Xiaoke;QIAN Shenyi
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    To upgrade the emergency management platform from its traditional role of information management to the intelligent process role of information, the massive knowledge about emergencies must be integrated. To better manage and use the emergency knowledge, it is necessary to build a knowledge database system based on the information technology. In view of the characteristics of knowledge in the field of emergency, the overall system objectives and the function requirements of the emergency knowledge database are proposed. The structure of the system is also provided. Meanwhile, the microcosmic and macroscopic principals for the system design are discussed. Based on the system goals and the design principles, some organization and unit models for the knowledge database are recommended. Each knowledge unit is composed of four elements, i.e. the laws and regulations, the technical specifications, the emergency knowledge and the inference rules. The organization mode is of four major categories and of three-layer. The top four major categories are the natural disasters, the accidents, the public health incidents and the social safety events. The types and the numbers of sub-classes of the middle layer are determined according to the specific situation of the province. The lowest level of the organization is every single knowledge unit. Combined with emergency management and the database technology, the method of the implementation of the knowledge database is proposed from the perspective of the software development. The database system is based on the MVC three-layer structure. Finally, based on the above design and analysis, a basic prototype of the system is proposed.
  • QI Na;SONG Lirong
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    At the present, more and more people acquire scientific and technological information through the Internet, especially medical information that is closely related to people's daily life. However, the quality of the information is various; the fact affects public confidence and has seriously impact on users' decision-making behaviors. To this end, the microblogging in health and medical field that have been widely forwarded is taken as a case, by using questionnaire survey, statistical analysis, expert interviews, comparative analysis, and other methods, the quality of disseminating information on network science and technology has been studied and the conclusions are drawn as follows: The poor quality of microblogging information is mainly caused by its properties of gray information, lack of research attention, and there is no sound system for regulatory constraints. In this context, the advices are proposed as below: (1) emphasizing on the quality of microblogging information in the field of medical and health; (2) improving the mechanisms for network information dissemination and management; (3) strengthening the theoretical research, developing evaluation criteria and indicators for the quality of medical and health information, and establishing a sound scientific and reasonable system for information quality evaluation.
  • Reviews
  • LI Gang;LI Hua;YANG Lingyuan;XU Yanji;NIE Chaoqun;ZHU Junqiang
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    The ignition and the stable combustion provide two critical points in the combustion studies and applications. With the plasma actuation, not only the gas flow is heated, but also a large quantities of chemical substances are produced by the non-equilibrium plasma, such as the excited molecules and free radicals, which could be used to realize a wide range of ignition, to reduce the ignition delay, to improve the stability of the flame and to expand flammable limits together with other advantages. A great amount of experiments and numerical simulations were carried out in Russia. This paper reviews the data available and discusses their treatments. Some conclusions on the main achievements and prospects of the future investigations in this field are made. The results definitely confirm that the field of the plasma ignition and the plasma-assisted combustion is highly promising for a number of industrial applications.
  • TIAN Yongfeng;HOU Hongwei;LIU Yong;HU Qingyuan;WANG An
    Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save
    In order to deeply study etheno-DNA adducts, the variety of DNA oxidative damages, repair mechanisms, and their products are summarized. The generative mechanism in vivo and analytical method of etheno-DNA adducts, including 1, N6-ethenoadenine (εAde), 1, N2- ethenoguanine (εGua), and 3, N4-ethenocytosine (εCyt) are reviewed. The current analytical methods of etheno-DNA adducts have been discussed, which include Immunoaffinity Chromatography/32P-postlabelling technique (IC-32P), Gas Chromatogeraph-Mass Spectrometer (GC-MS). and Liquid Chromatography-tandem Mass Spectrometer (LC-MS/MS). IC-32P has the excellent performance on the sensibility, but when determining etheno-DNA adducts, complex operations and many steps have been involved. As analytical devices, the characteristics of mass spectrometer make the device obtain ideal sensibility and specificity. GC-MS method has the lower limit of determination than that for LC-MS/MS method. As sample derivatization is needed, the sample usually cost more for the method of GC-MS during the pre-handling; LC-MS/MS method offers many practical advantages on the pre-handing, stability, selectivity, and sensibility. These advantages could enhance the efficiency of samples analysis. LC-MS/MS is the ideal analytical method for the research on etheno-DNA adducts. The mechanism of DNA oxidative damage is inconclusive. As the biomarkers of DNA oxidative damages, etheno-DNA adducts possess significant meanings on the risk evaluation of lipid peroxidation.