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   Science & Technology Review
2012, Vol.30, No. 11
18 April 2012

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卷首语

Science & Technology Review. 2012, 30 (11): 3-3. ;  doi:
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Abstract ( 93 )
科技风云

Science & Technology Review. 2012, 30 (11): 7-7. ;  doi:
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Abstract ( 97 )
封面图片说明

Science & Technology Review. 2012, 30 (11): 8-8. ;  doi:
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特别栏目

Science & Technology Review. 2012, 30 (11): 8-8. ;  doi:
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Science & Technology Review. 2012, 30 (11): 10-10. ;  doi:
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Science & Technology Review. 2012, 30 (11): 12-12. ;  doi:
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Science & Technology Review. 2012, 30 (11): 13-13. ;  doi:
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Science & Technology Review. 2012, 30 (11): 14-14. ;  doi:
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Science & Technology Review. 2012, 30 (11): 30-30. ;  doi:
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Science & Technology Review. 2012, 30 (11): 47-47. ;  doi:
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Science & Technology Review. 2012, 30 (11): 88-88. ;  doi:
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Science & Technology Review. 2012, 30 (11): 94-94. ;  doi:
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Science & Technology Review. 2012, 30 (11): 95-95. ;  doi:
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科技事件

Science & Technology Review. 2012, 30 (11): 9-9. ;  doi:
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Abstract ( 114 )
科技工作大家谈

Science & Technology Review. 2012, 30 (11): 11-11. ;  doi:
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Abstract ( 100 )
Exclusive

Science & Technology Review. 2012, 30 (11): 15-20. ;  doi:
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Abstract ( 426 )
Articles

Effect of Mold on Corrosion Behavior of Immersion Silver Finished Printed Circuit Board

ZOU Shiwen;XIAO Kui;DONG Chaofang;LI Huiyan;LI Xiaogang
Science & Technology Review. 2012, 30 (11): 21-26. ;  doi: 10.3981/j.issn.1000-7857.2012.11.001
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Abstract ( 172 )
The corrosion behavior of Immersion Silver (ImAg) finished Printed Circuit Board (PCB) in mold environment was studied using Scanning Kelvin Probe (SKP) technology. The mold growth behavior was observed by using stereo microscope and SEM, and the corrosion product was analyzed by EDS. Based on the results of SEM and EDS, mold could grow on the surface of PCB-ImAg specimens under hygrothermal condition, Aspergillus niger shows higher activity and has a priority growth characteristics. The activity of mold is a promoter in the localized (pore) corrosion process and the leakage of copper of PCB-ImAg covered by mold. SKP results show that the PCB surface potential as a whole increases with time. And the colony region of PCB occurs preferentially corrosion as the anode; then the corrosion product area enlarges gradually. Although the corrosion reaction generates small amounts of toxic Ag+, which inhibits the growth and metabolism of the spores, this do not prevent the corrosion of PCB-ImAg caused by mold from occurrence. ImAg finished technology is unable to completely inhibit the growth of mold on PCB surface, which could not fully meet the requirement of PCB anti-mildew.

Synodic Month Periodic Variations of Ionosphere

ZHAO Shuxian;WU Pingjing;MA Li
Science & Technology Review. 2012, 30 (11): 27-30. ;  doi: 10.3981/j.issn.1000-7857.2012.11.002
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Abstract ( 209 )
Gravitational attraction of the moon might cause synodic month periodic variation in the ionosphere, but it has not been observed so far. On June 29, 2004, France launched an ionospheric satellite DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions), that was placed on a quasi Sun synchroneous circular orbit. In this paper, the data observed by the Langmuir probe of the DEMETER satellite are split into two groups: the data on the dayside and the data on the nightside. The two groups of data are re-sampled, with the missing data being padded, and the signals on the dayside and the signals on the nightside are generated. For the two groups of signals, the solar day periodic variations are filtered out, SNRs of a series of periods are calculated, and SNR-period curves are obtained. The synodic month periodic variations of electron density, ion density and electron temperature on the dayside are shown clearly, but those on the nightside are not observed. Why? The gravitational attraction of the moon can cause the lunar atmospheric tide. During day time, the photoionization causes vertical variations of electron density, ion density and electron temperature, and lunar atmospheric tide can be observed by DEMETER satellite that was placed at the same altitude. At night, the photoionization stops and does not cause vertical variations of electron density, ion density and electron temperature, and the lunar atmospheric tide can not be observed by DEMETER satellite.

Quasi 27-day Reoccurrence Period and Structure of IMF Observed by ACE

MA Li;ZHAO Shuxian;WU Pingjing
Science & Technology Review. 2012, 30 (11): 31-37. ;  doi: 10.3981/j.issn.1000-7857.2012.11.003
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Abstract ( 233 )
ACE was launched on August 15, 1997 and placed into an orbit about the L1 point between the Earth and the Sun. The L1 point is one of several points where the gravitational attraction of the Sun and Earth are equal and in the opposite direction. The Parker spiral angle at L1 point with ACE MAG data is calculated and the data is converted to the polarity symbolic sequence. For any point in the sequence, the quasi 27-day reoccurrence period and the structure of IMF are detected through altering the sub-sequence centered on this point. And then, the reoccurrence structure is identified with the template matching method. Finally, the piecewise constant function fitting is used to obtain the piecewise constant period and structure. The obtained results are as follows: (1) in the period of 1999—2008, the reoccurrence period is mostly in the range of (27±2) days, with only one exception: a month from 2001-10-27 10:00 to 2001-11-28 12:00, the reoccurrence period is 21 days and 14 hours; (2) from 2001-01-08 12:00 to 2004-07-17 04:00, IMF is in a two fan disc structure; from 2004-07-17 05:00 to 2007-06-30 23:00, IMF is in a four fan disc structure; from 2007-07-01 00:00 to 2008-12-31 23:00, IMF is in a two fan disc structure.

Rock Slope Stability Analysis Based on Strength Reduction of Finite Element Method and Limit Equilibrium Method

CHEN Jianhong;ZHONG Fusheng;YANG Shan
Science & Technology Review. 2012, 30 (11): 38-42. ;  doi: 10.3981/j.issn.1000-7857.2012.11.004
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Abstract ( 182 )
A hybrid methodology combining strength reduction of Finite Element Method(FEM) with limit equilibrium theory is presented to evaluate rock slope stability by considering the demand for slope stability analysis and slope angle optimization of an open-pit, and it is applied to a case study for optimizing slope angle. The methodology uses the strength reduction of FEM to identify the plastic area in slope preliminary, which is supposed to be the most likely sliding surface. Thus the range of sliding surface inclination could be regularized. And then by taking this sliding surface as a start point of analysis, the limit equilibrium theory is used to calculate safety factors under different slope angles. By plotting the curve of safety factors with respect to different slope angles, the optimal inclination of a slope which is met to safety threshold could be determined. Finally, the upper slope located in the central part of open-pit iron mine, Cape of Lambert is presented to demonstrate this methodology. Results show that this approach is effective to deal with the analysis of rock slope stability.

Study of the Transfer Zone in Cuizhuang Area of the West Slope of Jinhu Sag

DAI Junsheng;SONG Shijun;WANG Xiatian;ZHANG Hongguo;ZHANG Hu
Science & Technology Review. 2012, 30 (11): 43-47. ;  doi: 10.3981/j.issn.1000-7857.2012.11.005
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Abstract ( 162 )
Tectonic transfer zone is an important component of the extensional tectonic system to balance deformation. Cuizhuang Transfer Zone is located in the middle of the western slope of Jinhu Sag. This paper studies the geological characteristics of Cuizhuang Transfer Zone, the relationship between it and hydrocarbon reservoirs and its division effect based on the analysis of the tectonic evolution history of the west slope, the distribution of faults and the sedimentary facies. It is shown that Cuizhuang Transfer Zone influences the provenances, the deposition of sand and the distribution of hydrocarbon reservoirs. It is the entrance of the lateral provenance and controls the distribution of the sand body. It is the boundary between the north and the south, where the structures and the sedimentary conditions are different. The sand in the transfer zone enjoys a good porosity and permeability. The transfer zone is a favorable zone for the accumulation of oil and gas. The transfer zone in the western slope acts as oil and gas reservoirs and the channel for oil and gas migrations. Cuizhuang Transfer Zone is one of the important factors to control hydrocarbon reservoirs of Funing Group in the western slope.

Modal Analysis on the Impact Factors of Horizontal-axis Wind Turbine Tower

XU Qingchun;LIU Lin
Science & Technology Review. 2012, 30 (11): 48-52. ;  doi: 10.3981/j.issn.1000-7857.2012.11.006
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Abstract ( 229 )
Taking a large tower of horizontal-axis wind turbine as an example, the factors affecting horizontal-axis wind turbine tower are analyzed by the test of four factors and three levels, the modals are calculated using matrix analysis. The finite element model is built and the modal analysis is completed by using the finite element software of ABAQUS. The factors including bottom of the tower openings, the total mass of the cabin and wind wheel (with hubs), the overall eccentric of the cabin and wind wheel (with hubs), and the wall thickness and diameter of the tower are considered in the modal analysis. Through the research of the factors on horizontal-axis wind turbine tower, the results show that the significant factors are the total mass of the cabin and wind wheel (with hubs), and the wall thickness and diameter of the tower, however the factor of the bottom of the tower openings could be ignored; the impact of the overall eccentric of the cabin and wind wheel (with hubs) on horizontal-axis wind turbine tower is determined by the degree of the overall eccentric of the cabin and wind wheel (with hubs), the bigger bias is, the bigger affected degree is.

Establishment and Applications of Fuzzy Comprehensive Evaluation Model for City Drinking Water Source Quality Assessment

ZHAO Xiaoliang;QI Qingjie;ZHAO Guozhi;ZHENG Jiao
Science & Technology Review. 2012, 30 (11): 53-56. ;  doi: 10.3981/j.issn.1000-7857.2012.11.007
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Abstract ( 188 )
In view of lack of strict attribute and intermediary in drinking water source form and class attribute, nine assessment factors which have much more influence on human health in drinking water source quality assessment are identified. For example, permanganate index, biochemical oxygen demand, total nitrogen, ammonia nitrogen, fluoride, total phosphorus, dissolved oxygen, etc. The ratio of i-th pollutant measured concentration to average value of its each water quality standard is used as the corresponding weight of i-th factor. And all the factors' weights are treated by normalization before taken into the assessment. Then fuzzy comprehensive evaluation model on water source quality assessment is established and applied to main water source quality assessment in Fuxin City. The results show that fuzzy comprehensive evaluation model on drinking water source quality assessment not only could identify the source water quality level, but also could find out the main pollutants and main pollution sources. The final analysis results of different assessment methods indicate that fuzzy comprehensive evaluation model on drinking water source quality assessment possesses validity and favorable applicability.

Pre-evacuation Time Experiment in Public Assembly Occupancy of School Under the Fire

WANG Jinhui;JIN Zeyang;TIAN Zhengang;JIN Ke;DONG Zhefeng;ZHENG Yuting
Science & Technology Review. 2012, 30 (11): 57-60. ;  doi: 10.3981/j.issn.1000-7857.2012.11.008
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Abstract ( 142 )
The calculation of evacuation time is an essential part of building evacuation safety design. Some investigations demonstrate that the effect of pre-evacuation time on evacuation time is highly significant. Therefore, the pre-movement time in evacuation time during a performance-based design should be considered. However, the essential data related to pre-evacuation time of public buildings in the case of fire is quite scarce. By carrying out an emergency evacuation experiment in classroom under fire-simulated condition, students' pre-evacuation time of assembly occupancy of school is focused on. Using video camera, a simulated evacuation process is completely recorded. The pre-evacuation time is defined as the time from smoke induced by tobacco spread to the classroom to the beginning of evacuation. With analyzing every one in the experiment, the data concerning with pre-evacuation times are collected. The statistical results of students' pre-evacuation times demonstrate that normal distribution or other distribution functions used in the previous publications are unable to characterize the students' pre-evacuation times. Using cumulative distribution function to express the pre-evacuation time is proposed and the cumulated distribution curve of pre-evacuation time is obtained by applying the method. In addition, the cumulated distribution of stochastic data generated according to the cumulative distribution function fits quite well with that of the experimental data.
Reviews

Historical Contributions and Inspirations of Classical Mechanics

MEI Fengxiang;WU Huibin
Science & Technology Review. 2012, 30 (11): 61-68. ;  doi: 10.3981/j.issn.1000-7857.2012.11.009
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Abstract ( 404 )
The development of classical mechanics could be divided into five stages, i.e. Newton mechanics, Lagrange mechanics, Hamilton mechanics, nonholonomic mechanics, and Birkhoff mechanics. The historical contributions of each stage are summarized, then from which the problems are found and inspirations are obtained.

Key Technique for Embedded Multicore OS

JIIANG Chunmao;NI Yuntao;HUANG Chunmei
Science & Technology Review. 2012, 30 (11): 69-75. ;  doi: 10.3981/j.issn.1000-7857.2012.11.010
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Abstract ( 151 )
At present, the emergence of multicore chip bring about the change in the computer operating system, many multicore technologies are rapidly come out not only in the application software development but also in the operating system research. In order to provide overall review of researchers on multicore operating system, the common problems that the current mainstream multicore operating systems are facing are analyzed; these problems include real-time scheduling algorithm, load balance, synchronization mechanism, task model, and their applications in the embedded domain. Finally, application examples based on multicore operating system—LITMUS are given by means of the discussion on the system structure, design method, basic principles, and scheduling algorithm, etc. Through the analysis on some key issues in the solution method, the basic idea for transplantation and scalability in the field of multicore embedded problems is given, at the same time, the blueprint for the future direction of the research is proposed.

R-tree Spatial Index Based on K-Means Clustering

YU Dongmei
Science & Technology Review. 2012, 30 (11): 76-79. ;  doi: 10.3981/j.issn.1000-7857.2012.11.011
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Abstract ( 181 )
At present, combining spatial clustering with spatial index is one of the techniques that could enhance data retrieval efficiency in the spatial database research. Based on the storage principles of spatial clustering and spatial index, K-Means clustering algorithm and the technical ideas behind improved algorithm are elaborated; the techniques of combining K-Means algorithm with spatial index method in spatial database are studied. Current research results of R-tree series spatial index technology based on K-Means algorithm air analyzed and their technical ideas for improving spatial retrieval efficiency and experiment results are described. The research shows that these techniques could enhance data retrieval efficiency to a certain degree. In the end, the future research trend of technique about combining clustering with spatial index is proposed.
科技评论

Science & Technology Review. 2012, 30 (11): 80-80. ;  doi:
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Science & Technology Review. 2012, 30 (11): 82-82. ;  doi:
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主编心语

Science & Technology Review. 2012, 30 (11): 83-83. ;  doi:
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Abstract ( 89 )
科技职场

Science & Technology Review. 2012, 30 (11): 84-84. ;  doi:
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Science & Technology Review. 2012, 30 (11): 85-87. ;  doi:
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Science & Technology Review. 2012, 30 (11): 89-92. ;  doi:
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