13 January 2015, Volume 33 Issue 1
    

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  • Explore the value of art in scientific activities
    ZHANG Kaixun
    Science & Technology Review. 2015, 33(1): 14-16. https://doi.org/10.3981/j.issn.1000-7857.2015.01.001
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    Arts and sciences are human activities of long history. Though difference lies in their study objects and way of thinking, art is of great value in scientific activities. Science is concerned with the law of physical world, through which human could solve practical problems. On the other hand, art pays attention to human's spiritual needs, longing for beauty and harmony in our heart, and this different way of thinking may help scientists to rethink the things which were once so familiar. Science is generally close to philosophy, likewise the individual scientist is not far from an artist.
  • Detecting expression of spindle protein gene INMAP in hepatoma cells by polyclonal antibody
    ZHU Yan, KANG Jingyan, WANG Yu, SUN Le, ZHANG Haijiang, LIANG Qianjin
    Science & Technology Review. 2015, 33(1): 17-21. https://doi.org/10.3981/j.issn.1000-7857.2015.01.002
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    To investigate the function of INMAP of spindle protein and its role in malignant cell proliferation, an INMAP polyclonal antibody is prepared. The prokaryotic expression of His-INMAP fusion protein is induced at 16℃ by adding 0.1 mmol/L isopropyl-β-D-thiogalactoside (IPTG), which is identified by SDS-PAGE analysis and western blotting assay. The inclusion body is treated with 4.0 mol/L urea to obtain soluble His-INMAP fusion protein antibody, fusion protein is purified using Ni Sepharose High Performance, and then the protein concentration and purity are detected. The purified protein antibody is injected into 4 Balb/c mice, then blood samples are collected from their hearts, and the anti- serum is isolated. The specificity of polyclonal anti- INMAP antibodies in unpurified and purified prokaryotically expressed products are analysed. In addition, the expression difference between normal liver cell L-02 and 5 hepatoma cell (PLC, HepG2, SUN449, SMMC-7721 and BEL-7402) is determined by western blotting assay. The results show that His-INMAP fusion protein mainly exists in insoluble inclusion bodies. Soluble protein is obtained with 4.0 mol/L urea treatment to solubilise inclusion bodies. Highly protein purity (94.1%) is harvested after purification. The polyclonal anti-INMAP antibody can bind antigen specifically. Moreover, INMAP is found existing polymorphically in hepatoma cells and its gene expression is down-regulated significantly in all tested hepatoma cells except PLC cell. Obviously, in this study the anti-INMAP polyclonal antibody is of high specificity, which lays a foundation of further study of INMAP functions.
  • Effects of stress sensitivity on reasonable water-flooding time and pressure level in fractured reservoir
    ZHENG Hao, SU Yanchun, ZHANG Yingchun, WANG Yuejie
    Science & Technology Review. 2015, 33(1): 22-27. https://doi.org/10.3981/j.issn.1000-7857.2015.01.003
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    For stress-sensitive fractured reservoirs, the decrease of seepage ability is inevitable due to reduction of pore volume caused by formation pressure drop in the process of development. How to effectively restrain the influence of it on the development effectiveness and ultimate recovery is the key to developing fractured reservoir development strategies. This paper takes a fractured reservoir in Bohai Oilfield as an example to study the effects of stress sensitivity on reasonable water-flooding time and formation pressure level. The results show that without consideration of stress sensitivity, the reasonable water-flooding time was when the formation pressure dropped to saturation pressure, while with consideration of stress sensitivity, it was determined by the degree of stress sensitivity. When the retention rate of permeability was above 80% at reservoir saturation pressure, the reasonable waterflooding time was also when the formation pressure dropped to saturation pressure. Otherwise, water-flooding must be carried out at original reservoir pressure. Meanwhile, the formation pressure for reasonable water-flooding time should be kept constant, or slightly elevated with consideration of subsequent developing measures and comprehensive adjustment.
  • Optimization of the ground engineering system for CO2 flooding in Yaoxi block
    HUANG Yeqian, LI Yufeng, TAN Wenjie
    Science & Technology Review. 2015, 33(1): 28-32. https://doi.org/10.3981/j.issn.1000-7857.2015.01.004
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    The gathering and processing technology for CO2 flooding produced fluid is a key issue closely related to the technical feasibility for recovery enhancement by CO2. An optimization and transformation program for ground engineering for CO2 flooding pilot test in Yaoxi block of Yaoyintai oilfield has been developed based on analysis of properties of the produced fluid and associated gas, adaptability for the gathering system, existing system improvement and processing for associated gas. This paper suggested that to minimize engineering investment and improve economic benefit of the project, it is a priority to analyze the adaptability of existing systems and access the feasibility using existing facilities in CO2 flooding pilot test at existing oilfields.
  • Anti-wax application of crude oil flow improver
    TANG Zhiwei, DANG Wei, TAN Wenjie, WANG Lili, HU Changchao
    Science & Technology Review. 2015, 33(1): 33-37. https://doi.org/10.3981/j.issn.1000-7857.2015.01.005
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    The AT-2, a new crude oil flow improver, has been developed targeting the wax deposition problem in an oilfield. Antiwax and water separation experiments were carried out. The result showed that AT-2 had a satisfactory anti-wax effect on the produced liquid sample with watercut of 10%~50%. When the watercut was 40%, the maximum wax reduction rate was achieved, reaching 75.36%; meanwhile, the water separation was not affected when the concentration of AT-2 was lower than 100 mg/L. Considering the watercut of the wells having the wax problem is lower than 50%, the application of AT-2 would solve the wax deposition problem.
  • Coupling laws of mud property, flow and heat transfer in borehole of deepwater subsea mud lift drilling
    GUO Xiaole, LONG Zhihui, SU Kanhua, LIU Jingcheng
    Science & Technology Review. 2015, 33(1): 38-42. https://doi.org/10.3981/j.issn.1000-7857.2015.01.006
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    The calculation of wellbore temperature and pressure is an important part in deepwater subsea mud lift drilling (SMD) design. Considering the influence of temperature, pressure and mud property, this study established a model of flow and heat transfer in the borehole of SMD. The results show that affected by the low seawater temperature, the upper wellbore annulus temperature was lower than the mud entrance temperature; the temperature in the borehole of SMD was lower than that of regular deepwater drilling; the potential safety problems caused by gas hydrate formation need to be watched. The pressure gradients in the borehole were different between the sea section and underground section. The pump pressure above the ground was lower than the circulating pressure loss, and the pressure in the borehole of SMD was lower than that in regular drilling. Both mud density and viscosity had impact on the equivalent circulating density (ECD) and pump pressure and temperature in the borehole, while the former had relatively large impact on ECD, and the latter had relatively large impact on the pump pressure and temperature. When both were considered, the calculation error of pump pressure would be greatly reduced.
  • Hydraulic fracturing experiment of coalbed methane well under triaxial stress
    DONG Guang
    Science & Technology Review. 2015, 33(1): 43-46. https://doi.org/10.3981/j.issn.1000-7857.2015.01.007
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    For further understanding of hydraulic fracture initiation and propagation mechanisms of coalbeds, hydraulic fracturing experiments under triaxial stress were carried out on the raw coal specimens from a coalmine with a large-size true triaxial hydraulic fracturing test system. The initiation and propagation characteristics of coalbed hydraulic fracture were studied under different triaxial stress states. The experimental results indicate that the stress state and coal cleat had a direct effect on hydraulic fracture initiation and propagation. The existence of small-scale cleat caused the hydraulic fracture propagation pressure to fluctuate frequently within a narrow range. The swerve of many fracture propagation paths was observed, and the filtration of fracturing fluid led to loss of propagation pressure. These problems are not conducive to the formation of high conductivity hydraulic fracture. The coalbed hydraulic fracture will be more complex with lesser degree of principle stress difference, and horizontal and vertical fractures may be both generated. This experiment may provide references for further exploration of coalbed fracturing mechanisms.
  • Transportation characteristics of drilling cuttings in gas drainage borehole
    WANG Yonglong, SUN Yuning, WANG Zhenfeng, SONG Weibin
    Science & Technology Review. 2015, 33(1): 47-51. https://doi.org/10.3981/j.issn.1000-7857.2015.01.008
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    Based on pneumatic conveying theory, the suspension model of drilling cuttings has been established, the minimal startup speed of the drilling cuttings was derived, and the influence of diameter of drilling cuttings, friction coefficient, and drilling angle on the start-up speed was analyzed. The results show that in downward drilling engineering, there existed a drilling angle θD when the start-up speed reached its maximum value. When the drilling angle was in the range of θD～0, the start-up speed va increased with increase of the absolute value of the drilling angle; when the drilling angle was in the range of θD～-π/2, va decreased slightly with increase of the absolute value of the drilling angle. In upward drilling engineering, there existed a drilling angle θU. When the drilling angle was in the range of 0~θU, the start-up speed va decreased gradually with increase of the drilling angle; when the drilling angle θ＞θU, the drilling cuttings will slide under gravity. Similar influence of the friction coefficient on the minimal start-up speed was obtained. When the drilling angle θ=-π/2, different curves met in one point, indicating that the start-up speed had nothing to do with the friction coefficient.
  • Intelligent control system of local fan based on fuzzy control
    LI Wenhua, LI Chunlei, YU Ning
    Science & Technology Review. 2015, 33(1): 52-56. https://doi.org/10.3981/j.issn.1000-7857.2015.01.009
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    An intelligent control system of local fan based on fuzzy control theory was designed in view of the defects of control system of local fan in conventional mines. The roadway parameters of temperature, gas concentration and the equivalent depth were introduced, the functional relationship of voltage of frequency converter and field temperature and gas concentration was established by fuzzy control theory, and the algorithm of voltage of frequency converter based on the influence of equivalent depth of roadway was established to realize the intelligent control of local fan by frequency control. Practical operating results show that the system can guarantee the ventilation safety of excavation roadway, save 36.8% of electricity consumption and maximize the efficiency of the local fan.
  • Determination of classification of rock burst risk based on random forest approach and its application
    LI Baofu, LIU Yonglei
    Science & Technology Review. 2015, 33(1): 57-62. https://doi.org/10.3981/j.issn.1000-7857.2015.01.010
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    Arandom forest (RF) modelfor rock burst identification was established on the basis of the RF theory to forecast rock burst risk rapidly and accurately. Ten indices, ie, coal seam, dip angle, buried depth, structure situation, change of dip angle, change of coal thickness, gas concentration, roof management, pressure relief and shooting were used as the criterion indices for rock burst prediction in the proposed model on the basis of analysis of rock burst impact. Twenty-four typical rock burst instances of a coal mine were used to createa RF classifier. RF is a combination of tree predictors, and variable importance is measured by Gini importance (GI) when the forest grows. The GI shows that structure situation was the most important indicator, followed by shooting and dip angle. Another 12 groups of rock burst instances were tested as forecast samples, and the predicted results were in accordance with actual situation.
  • Multiparameter optimization method for downward drift mining based on PLS
    SHANG Xueyi, LI Xibing, WANG Zewei, PENG Kang
    Science & Technology Review. 2015, 33(1): 63-69. https://doi.org/10.3981/j.issn.1000-7857.2015.01.011
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    To study the relationship between multiple parameters and stability of downward drift, orthogonal simulation and partial least squares regression were used to analyze factors affecting the stability of downward drift. Safety coefficient and reliability analysis were applied to optimize these parameters. On the basis of that, an industrial test was conducted. The results show that: 1) The factors affecting tensile stress of the loading layer in a descending sequence in terms of significance are thickness of the loading layer, drift width, drift height, two-sided elastic modulus of the drift, elastic modulus of the loading layer and Poisson ratio of the backfill, and the first three factors are more effective than the others. 2) Satisfactory fitness and forecast were obtained through partial least squares regression with errors controlled within 15%. 3) The reliability analysis is more reasonable than the safety coefficient method in optimizing multiple parameters, which can achieve safer, more efficient and economical downward drift exploitation. The satisfactory results of industrial test indicate that partial least squares regression has theoretical and practical values in optimizing multiple parameters for downward drift mining.
  • Characteristics of mechanical response of surrounding rocks in deep hole pillarless retreating mining at deep stope
    LUO Zhouquan, CHEN Jie, XIE Chengyu, WANG Wei, QIN Yaguang, CHEN Yijun
    Science & Technology Review. 2015, 33(1): 70-74. https://doi.org/10.3981/j.issn.1000-7857.2015.01.012
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    A three-dimensional numerical analysis model was developed using the complex geological modeling techniques, Surpac and FLAC3D. The initial geo-stress field was obtained by using multiple linear regression method, and the distribution law of in-situ geo- stress field around the stope was obtained by geometric cross- scale model- building technology. On the basis of that, the characteristics of mechanical response of surrounding rocks in deep hole pillarless retreating mining at deep stope were studied. The results showed that: 1) The maximum tensile stress of 0.40 MPa and the maximum horizontal displacement of 28.2 mm were observed at south side of the stope near the Y-central axis. The maximum vertical stress of surrounding rocks was found to be significant at stope roof near the Y-central axis with the maximum value of 27.43 mm. Plastic failure occurred in these corresponding regions. 2) Field monitoring and security measures need to be strengthened near the Y-central axis. The hole net parameter needs to be adjusted in eastward lateral caving due to accumulated damage of blasting. In the south side of the stope, it is necessary to increase presplit holes and reduce single hole explosive load and the initiation dose of each segment to prevent the overbreak of the pillar to affect the stability of the entire extent.
  • Analysis for wind resistant stability of steel box girder bridge in the construction process in high wind speed region
    ZHANG Jianlong, LUO Zuolong, DONG Fenghui, LIU Luping
    Science & Technology Review. 2015, 33(1): 75-80. https://doi.org/10.3981/j.issn.1000-7857.2015.01.013
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    Nonlinear aerodynamic stability of the maximum cantilever state of long- span continuous steel box bridge in the construction process was analyzed. Aerodynamic stability analyses based on wind load nonlinearity and geometry nonlinearity were proposed. A cross-sea bridge was taken as the subject, and the effects of static wind force and buffeting force were calculated and the maximum RMS of displacement response in the longest cantilever state was determined. The nonlinear aerodynamic stability analysis of the maximum cantilever state was carried out taking static wind force and buffeting force as the external load and the displacement under the dead load as initial defect. The results show that with the increase of wind speed, the horizontal and vertical displacement of the cantilever end and mid-span of the steel box girder both had a nonlinear increasing trend; the displacement response changed with the positive and negative transformation of wind attack angle, so the influence of wind load should not be ignored. Due to high stiffness of the steel box girder, the buckling critical state did not appear within the wind speed of 120 m·s-1, but the horizontal and vertical displacement of the cantilever end were relatively large. Three measures for wind resistance were proposed to ensure safety of the personnel and smooth closure process.
  • Experimental study on heat release rate of PVC desktop decoration materials
    LIU Hui, WANG Zhixing, LI Haihang, CHEN Mingyi, MENG Na
    Science & Technology Review. 2015, 33(1): 81-85. https://doi.org/10.3981/j.issn.1000-7857.2015.01.014
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    This paper studies the heat release rate of PVC desktop decoration materials, aiming to provide reference for fire prevention and control. PVC desktop decoration materials have beautifying and protecting functions, so they are widely used in daily life. However, fire accidents caused by these materials cannot be underestimated in recent years. When a fire accident happens, all kinds of decoration materials not only are supporters of combustion, but also release toxic gas in the process of combustion which is the main reason for casualties. Therefore, the heat release rates of PVC decoration materials with thicknesses of 1, 2 and 3 mm were measured based on the oxygen consumption principle using ISO 9705 standard small size heat release rate test bench. The test results show that the PVC decoration materials can be ignited by 2 mL n-heptane, and the maximum temperature reached more than 800℃. The maximum heat release rate of different samples increased with the increase of thickness, being 5.82, 4.41 and 2.83 kW/s. The total heat release rate took on an increasing trend. With the increase of sample thickness, the ignition time was prolonged, that is, the materials were more difficult to be ignited. A large amount of black smoke and pungent odors were released in the combustion process.
  • Influence of network topology on network capacity
    SUN Lei, LI Rong, JIN Cong, CHEN Xiaoguo
    Science & Technology Review. 2015, 33(1): 86-89. https://doi.org/10.3981/j.issn.1000-7857.2015.01.015
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    Three typical complex network models and corresponding traffic routing models were established to carry out numerical computation and simulation of topological indicators and network capacity, and empirical analysis of how network capacity is influenced by network topology was conducted. The results show that numerical calculation results and experimental results of the capacity of three different networks were roughly consistent. With existence of the core node, scale-free network had the shortest average travel path, and the proportion of the largest betweenness was much higher than that in other networks, leading to minimum capacity of the scale-free network; the proportion of the largest betweenness of nodes in random network was lower than that in other networks, leading to maximum capacity of the random network. The increase of average degree resulted in significant increase of network capacity, but the contribution of different topological indicators was not the same. Understanding the quantitative relation between network topology and network capacity is beneficial to conducting effective prevention and intervention concerning dynamic processes in the network.
  • Speaker recognition method based on combination of kernel functions of SVM
    FAN Chijie, SI Qiaomei, XU Yan, ZHANG Dan, CAI Chunhua, YU Xu
    Science & Technology Review. 2015, 33(1): 90-94. https://doi.org/10.3981/j.issn.1000-7857.2015.01.016
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    In speaker recognition systems, if the original data distribution is unknown, the choice of inappropriate kernel functions will result in poor support vector machine (SVM) learning performance. Thus a speaker recognition method based on a multi-grid search of parameters and a combination of kernel functions is proposed in this paper. First, the method constructs a hybrid kernel function by linearly weighted polynomial and RBF kernels. Then it proposes a multi-grid search method to adjust the weights, and thus the hybrid kernel function can adapt to the current data distribution. Finally, a SVM classifier is trained to obtain the classification results. Simulation experiments on TIMIT datasets and noisy datasets show that the recognition performance of SVM classifiers using a combination of kernel functions is better than that using linear kernels, polynomial kernels, and RBF kernels. Therefore, the proposed method can effectively improve the performance of speaker recognition systems.
  • Optimal configuration model of non-repairable spare parts based on non-Poisson distribution
    XU Tingxue, DONG Qi, YANG Jikun, WANG Haowei
    Science & Technology Review. 2015, 33(1): 95-99. https://doi.org/10.3981/j.issn.1000-7857.2015.01.017
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    This paper studies the optimal configuration model of non- repairable spare parts whose demand obeys non- Poisson distribution to overcome the limitation of existing models. The characteristics of non-repairable spare parts in two-echelon inventory system were analyzed, and the assumption of the demand obeying Poisson distribution was relaxed, so that a universal model for the satisfaction rate of non-repairable spare parts whose demand obeys non-Poisson distribution was established. On the basis of that, an optimal configuration model for non-repairable spare parts in the two-echelon inventory system was established by setting minimum configuration cost as the optimization target and satisfaction rate as the constraint. The optimization scheme was solved by Genetic Algorithm. The optimization and verification results show that the satisfaction rate of the system reached 95.02% with minimum total cost, which is in accordance with results calculated by Opus 10, demonstrating the feasibility and reliability of the model.
  • Laboratory diagnosis of Ebola virus disease: A review
    QIAO Jinjuan, LUO Jun, WEI Hongping
    Science & Technology Review. 2015, 33(1): 100-106. https://doi.org/10.3981/j.issn.1000-7857.2015.01.018
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    Ebola virus disease (EVD) caused by Ebola viruses (EBOV) is an acute hemorrhagic infectious disease. Because of its high infectivity and high mortality rate(up to 90%), EBOV is listed as one of the most dangerous viruses to human by World Health Organization. Although US FDA gave it emergency clearance to use an experimental drug TKM-Ebola, there is no Ebola vaccine available yet. Rapid, accurate, simple and reliable laboratory diagnostic tests are required in suspected cases for timely treatment, epidemiological investigation and controlling the spread of the EVD. This review summarizes the principles, applications and progress of the laboratory diagnosis of EVD, covering virus isolation by cell culture, electron microscopy, reverse transcriptase polymerase chain reaction (RT-PCR) assay, antigen detection, antibody-capture enzyme-linked immunosorbent assay and serum neutralization test.
  • Earthquake- triggered individual landslides and slope seismic responses across mainland China before the 2008 Wenchuan earthquake
    XU Chong
    Science & Technology Review. 2015, 33(1): 107-119. https://doi.org/10.3981/j.issn.1000-7857.2015.01.019
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    This article focuses on earthquake-triggered individual landslides and slope seismic responses, and is the continuation of "Earthquake-triggered Landslides across Mainland China Before the 2008 Wenchuan Earthquake". Individual landslides or stability of slopes under seismic forces in cases before the 2008 Wenchuan earthquake are reviewed in detail using the following approaches: 1) geological analysis of real earthquake- triggered landslides or slope stability analysis under seismic forces; 2) conventional computational mechanics analysis, including the Newmark method and ultimate equilibrium method; 3) finite element analyses, such as GeoStudio and FLAC platforms; 4) discrete element analyses, such as UDEC and other programs applied in the filed of seismic landslides; and 5) physical models. This review aims to provide references for similar studies in the future.

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