08 April 2012, Volume 30 Issue 10

    

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  Electrochemical Noise Detection for SCC Behavior for 2024-T351 Aluminium Alloy in Acid NaCl Solution

  SHENG Hai;DONG Chaofang;YANG Zhiwei;XIAO Kui;CUI Zhongyu;LI Xiaogang

  . 2012, 30(10): 18-23. https://doi.org/10.3981/j.issn.1000-7857.2012.10.001

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  The stress corrosion cracking (SCC) behavior of 2024-T351 aluminium alloy in acid NaCl solution was studied by using the electrochemical noise technique. The electrochemical noise signal was recorded during the immersion test of the Wedge Opening Loading (WOL) specimen in the Zero Resistance Ammeter (ZRA) mode. The characteristic parameters were analyzed in time and frequency domains, respectively. The results indicate that SCC process of AA2024-T351 is not continuous. The current noise could be used to analyze the nucleation and propagation processes of SCC. During the nucleation period of SCC, the transient peaks could be observed, which was characterized by the small fluctuation amplitude of the current noise. This implies that the alternating film rupture and re-passivation process is dominant on the specimen surface. With the immersion time increasing, the characteristic peaks are observed. It is indicated that the crack propagation occurs. Meanwhile, the amplitude of the characteristic peaks increases and the periodic character could also be observed. The wavelet decomposition provides a strong tool to distinguish the nucleation and propagation processes of SCC according to the different current energy distribution.
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  A Fluid-structure Coupling and Dynamic Model of Ship Anti-shock Layer for Underwater Explosion Wave Isolation

  LIU Dongyue;WANG Yu;CHEN Yong;DU Jianye;DU Zhipeng

  . 2012, 30(10): 24-28. https://doi.org/10.3981/j.issn.1000-7857.2012.10.002

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  A fluid-structure coupling and dynamic model of ship anti-shock layer for underwater explosion wave isolation is developed to describe the complex structural dynamics and hydrodynamics characteristics of the anti-shock layer due to underwater explosion based on the multi-DOF dynamic theory, Taylor's flat plate model and DAA1 methods. The anti-shock layer shock response is split into three sequential steps: stage I is the one-dimensional fluid-structure interaction problem during the blast loading event, and results in a accelerated motion of the outer face sheet, and the cavitation occur in the water; during stage II the core crushes while the velocity of the outer face sheet bring down, additional impulse due to the water particles play an important role; stage III is the retardation phase over which the anti-shock layer is brought to rest by elastic restoring force and fluid pressure. The third-stage analytical procedure is used to obtain the dynamic response of the anti-shock layer to an underwater explosion. The analytical procedure and case study indicate the proposed model can deal with the ship anti-shock layer with complex core structures and the core density have a significant impact on the cushion effects of the ship anti-shock layer. The influence of the core density to the cushion performances is analyzed. These performances can be used to determine the optimal geometry to maximize shock resistance for a given mass of the anti-shock layer.
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  The Unloading Characteristics of Metal in During Dynamic Response

  HUANG Yong;PAN Hao;HU Xiaomian

  . 2012, 30(10): 29-33. https://doi.org/10.3981/j.issn.1000-7857.2012.10.003

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  The unloading characteristics are studied to explain the difference between the simulation results and the experimental data in this paper. The different elastic-plastic limiting conditions between the loading and the unloading processes are used to describe the quasi-elastic unloading of the earlier unloading. The critical damage model and the Steinberg-Guinan constitutive model are used to simulate the shock-unloading spallation process and the second loading process of Fe and Al. The simulation results indicate that the method used in this paper can describe quasi-elastic phenomena reasonably well. The results of the damage evolution and the spallation compare favorably with the experiment data at the complete spallation. But in the case of Al experiment, the incomplete spallation occurs because of the lower shock velocity, and it can not be described well with the macroscopic damage evolution model, which explains the difference between the simulation results and the experimental data.
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  Petroleum Geologic Characteristics of Sao Francisco Basin, Brazil

  PANG Zhenglian;FAN Tailiang;HE Hui;WANG Jincai;LIN Lin

  . 2012, 30(10): 34-38. https://doi.org/10.3981/j.issn.1000-7857.2012.10.004

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  Both basic and petroleum geology characteristics of Sao Francisco Basin, Brazil are studied and analyzed systematically with basin resource evaluation. According to the research, the basin possesses a long and complicated tectonic evolution history. It underwent the stages of lift, passive continental margin, and foreland in turn. Each stage left its feature in the basin. Three main sequences are formed in the basin: Espinhaco Group, Macaubas Group and Bambui Group. In the basin, effective source rock, favorable reservoir and regional caprock all develope in the Bambui Group and Macaubas Group. Meanwhile, the source-reservoir-cap assemblage in the basin is favorable, and the effective traps are plenteous, including structural traps, stratigraphic traps, and structural-stratigraphic traps. Through the research of accumulation, regional unconformity and fractures formed during Brasilia Orogeny are defined as the migration pathway, which facilitated the accumulation of hydrocarbon in different traps. Moreover, compared with the same kind of basins in the world, the result shows the Sao Francisco Basin possesses favorable petroleum potential.
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  Finite Element Numerical Simulation for Tight Reservoirs

  ZHANG Yun;XUE Liang

  . 2012, 30(10): 39-42. https://doi.org/10.3981/j.issn.1000-7857.2012.10.005

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  The fluid flow is non-Darcy flow in a tight reservoir. A startup pressure gradient is necessary for the flow in the tight reservoir porous media. The numerical simulation technology and software are mostly based on the Darcy seepage and could not effectively simulate the non-Darcy flow for tight reservoirs. In this paper, considering the complexity of the tight reservoir, the non-Darcy flow and the nonlinear characteristics, the oil-water two-phase compressible flow continuity equation, the motion equation, the state equation and the auxiliary equation are derived, to establish the oil-water two-phase non-Darcy flow mathematical model for the reservoir. The startup pressure gradient is considered in this model. The model is discretized for the low permeability and the strong heterogeneity in the tight reservoir with the finite element to be applied to complicated boundaries, high order differential equations, and weak grid orientations, with a high calculation precision. The numerical solution equation for saturation and pressure is obtained. The method is verified by examples.
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  Probability Analysis and Verification of Cavity Instability Based on FLAC^3D-RSM

  LUO Zhouquan;TAN Langlang;DENG Qiao

  . 2012, 30(10): 43-48. https://doi.org/10.3981/j.issn.1000-7857.2012.10.006

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  In view of the safety misadventure due to many residue mined-out cavities after mining in practical projects, the stability of cavities must be evaluated accurately. The cavities in 54-6^# mine were taken as an example in this study. Using the powerful pre-processing functions of Midas, the grid model was generated to be used in FLAC^3D for numerical analyses. Results show that there has a large tensile stress on both sides of the cavity. In view of this fact, with the response surface calculation method, the possibility of instability damage of the cavity is analyzed. It is shown that the cavity imposes the obvious instability risk. Then, the cavity model was measured twice, to validate the accuracy of the results and verify the conclusion of the numerical analysis and the instability probability analysis on the cavity. This paper provides a reliable evaluation method for the stability of mined-out cavities.
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  The Assumption of Manned Cabin in Ultra-high Temperature Mine

  HU Hanhua;WEI Yaxing;HE Falong

  . 2012, 30(10): 49-53. https://doi.org/10.3981/j.issn.1000-7857.2012.10.007

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  Along with the development of deep mining, in future, ultra-deep mines face the problem of ultra-high temperature is inevitable. Therefore, it is necessary to make a forward-looking discussion on the ultra-high temperature of underground mining. The implementation of automation and intelligentization in underground mining is unavoidable for the complex environment, especially the ultra-high temperature. These highly automated, intelligent devices need on-site maintenance by operating persons; however, the problem is that people can not directly descend to the ultra-high temperature mine without special unit. As a result, an assumption of manned cabin is put forward to prevent from complex environment of ultra-high temperature. By means of further analysis, it is illustrated that the key technical problems in manned cabin design are refrigeration and heat insulation technology. Theoretical estimates and numerical simulation techniques were used to test and verify. Other challenges to achieve manned cabin, such as temperature control system, environment control system, surveillance system, mobile technology, energy, power supply system, and other essential systems are also introduced. The solution to each technical problem is briefly described and its feasibility is discussed as a foresight about the future ultra-high temperature mining environment.
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  A Grey Literature Classification System Based on the Organizational Structure——for Use by Chinese Association for Science and Technology

  LU Ruihua;QIAO Xinge

  . 2012, 30(10): 54-58. https://doi.org/10.3981/j.issn.1000-7857.2012.10.008

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  Grey literature is produced and widely applied in the researches of science and technology, as an important reference source. Developed countries pay great deal of attentions to the collection of the important grey literature. Different departments of Chinese Association for Science and Technology (CAST) have accumulated a great many of academic conference proceedings and working documents, majority of which belong to the category of grey literature. In order to manage better the grey literature produced by Chinese Association for Science and Technology, a grey literature classification system is proposed based on the organizational structure of CAST, which is divided into four levels. The first and second level categories are constructed according to the organizational structure of CAST, with the first category reflecting the three basic sources of CAST literature, that is, from Chinese Association for Science and Technology, from national societies and from local associations of science and technology, and with the second category reflecting subordinate institutions under the first level. The categories of the third and forth levels are constructed according to the publication types and the publication years of literature, respectively. This classification system may better reflect the achievements made by different departments of the CAST, and facilitate the handling of the literature.
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  Diversity of Soil Fungi in the Different Developmental Stages of Jatropha curcas L. Forests in Yongsheng County of China

  GU Yong;YIN Yao;XIONG Zhi;HUANG Xiaobo;CHEN Xiying

  . 2012, 30(10): 59-64. https://doi.org/10.3981/j.issn.1000-7857.2012.10.009

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  The fungi are an important component to the biomass of the forest soil and microbial flora. Through scene sampling, indoor culturing, observing, and exterminating, soil fungi quantity's ecology distribution and fungi class group of three kinds of different age of Jatropha curcas L. forests in Yongsheng County is comparatively analyzed with the related soil nutrient's relations. The result indicates that the soil fungi quantity variance between the different age of forests is remarkable, appearing as the quantity in the years of 21 to 30 > in the years of 11 to 20 > in the years of 1 to 10. Soil fungi has a significant variance of vertical distribution, appearing as the most in the depth range of 10—15cm, and the least in the depth range of 25—30cm. The fact indicates that in the soil depth of 10—15cm, root distribution is densified, root exudation is massive, porosity is high, moisture is adequate, and it provides abundant nutrition and appropriate living conditions. Saccharomyces (Meyer) Reess is the dominant genus among the 20 genera of fungi isolated from soil in the three kinds of different growing stages of Jatropha curcas L. forests; it plays an important role in the microecological balance formation of the Jatropha curcas L., and they are the superior fungal flora. Through comprehensive comparison and analysis on the fungal diversity index, it is found that the Shannon-Wiener diversity index and evenness index of fungal flora isolated from the Jatropha curcas L.forest with the ages of 11 years to 20 years is higher than that from 1 year to 10 years and 21 years to 30 years, the fact might be closely related to soil fertility and forest health.
Reviews
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  Review on Barium Titanate Based Composites with High Energy Storage Density

  WANG Yajun;WU Xiaojuan;ZENG Qingxuan

  . 2012, 30(10): 65-71. https://doi.org/10.3981/j.issn.1000-7857.2012.10.010

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  Dielectric materials with high dielectric constant are widely used because of their excellent properties in energy storage, and play an important role in the area of electrical and electronic technologies. With the development of electronic industry, high energy density dielectric materials attract more and more attentions, and various novel dielectric materials with high energy storage density were developed. Dielectric materials with high energy storage density have high dielectric constants and high breakdown strength. It is an important issue to improve the energy storage density of dielectric materials. This paper reviews the latest development of high energy storage density dielectric materials, and discusses the modification of barium titanate to improve the energy storage density. Three approaches are adopted to achieve high electric energy density, namely, doping modification, surface coating and composite materials preparation. The main discussion is focused on the preparation of barium titanate/polymer composites, and the factors affecting dielectric properties, of which the compatibility of interface between barium titanate and polymer is of great importance. The developing direction of the composites is in the improvement of the dispersity property of particles in the polymer matrix, the selection of filling particles and polymer matrix and the control of preparation process conditions.
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  Research Progress on Inhibitors of Protein Tyrosine Phosphatase-1B

  LIU Xia;FENG Changgen

  . 2012, 30(10): 72-79. https://doi.org/10.3981/j.issn.1000-7857.2012.10.011

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  Protein-tyrosine phosphatase-1B acts as a negative regulator of the insulin signal transduction, serving as a new therapeutic target in type 2 diabetes and obesity. Inhibitors of PTP-1B may be beneficial in the treatment of type 2 diabetes and obesity. This paper reviews recent progresses of researches on inhibitors of PTP-1B, with PTP-1B inhibitors obtained by chemical synthesis being summarized, including vanadate compounds, phosphate compounds, peptide compounds and others.