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   Science & Technology Review
2011, Vol.29, No. 26
18 September 2011

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Science & Technology Review. 2011, 29 (26): 3-3. ;  doi:
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科技风云

Science & Technology Review. 2011, 29 (26): 7-7. ;  doi:
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封面图片说明

Science & Technology Review. 2011, 29 (26): 8-8. ;  doi:
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特别栏目

Science & Technology Review. 2011, 29 (26): 8-8. ;  doi:
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Science & Technology Review. 2011, 29 (26): 10-10. ;  doi:
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Science & Technology Review. 2011, 29 (26): 12-12. ;  doi:
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Science & Technology Review. 2011, 29 (26): 84-84. ;  doi:
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科技事件

Science & Technology Review. 2011, 29 (26): 9-9. ;  doi:
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科技工作大家谈

Science & Technology Review. 2011, 29 (26): 11-11. ;  doi:
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Exclusive

Science & Technology Review. 2011, 29 (26): 15-17. ;  doi:
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Articles

Critical Reappraisal of Ediacaran Doushantuo Animal Gastrula Fossils: New Insights from Synchrotron X-ray Microtomographic Anatomic Study

YIN Zongjun;ZHU Maoyan
Science & Technology Review. 2011, 29 (26): 18-24. ;  doi: 10.3981/j.issn.1000-7857.2011.26.001
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Abstract ( 351 )
Exquisite phosphatized eggs and embryos from the Ediacaran Doushantuo Formation (Weng'an biota, ca.580Ma) found in Guizhou Province, southwestern China have greatly expanded our understanding of the embryology and diversity of early metazoans. These Doushantuo animal fossils are dominated by uncleaved eggs and cleavage-stage embryos; specimens at later developmental stages such as gastrulae, however, are extremely rare. To obtain more affinity information about the gastrula fossils, phase contrast-based synchrotron X-ray microtomography and scanning electron microscopy were employed to perform morphology and anatomy investigations. The results suggest that the fossils which were interpreted as gastrulae formed by invagination previously probably have no relationship with animals but multicellular algae in affinity.

Synthesis of Hydrophobically Associated Copolymer Three-Component Copolymer and Their Properties

SONG Chunlei;AN Huiyong
Science & Technology Review. 2011, 29 (26): 25-29. ;  doi: 10.3981/j.issn.1000-7857.2011.26.002
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Abstract ( 325 )
Hydrophobically associated poly (AM/AMPS/SMA) were prepared by free radical micellar copolymerization. The structure of the copolymer was characterized by FTIR. The influences of several factors on the apparent viscosity are studied, such as the initiation temperature, the amount of initiator, the monomer concentration, the hydrophobic monomer concentration, the surfactant concentration, and the monomer proportion. The results show that after incorporating anions and hydrophobic groups at the same time in the backbone of the polyacrylamide, the viscosity of the copolymer aqueous solution increases significantly under the coordination of the electric viscosity of anions and the hydrophobic association property of hydrophobic group. The hydrophobic associative behavior of the copolymer is studied by the fluorescence probe technique and, at the same time, the rheological properties of the copolymer aqueous solution are also investigated.

Release Kinetics of Herbicide in Fertilizer-herbicide Granules with Effervescent Characteristics

HUA Quanxian;HU Bin;TANG Jianwei;LIU Yong;WANG Lisuo
Science & Technology Review. 2011, 29 (26): 30-33. ;  doi: 10.3981/j.issn.1000-7857.2011.26.003
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Abstract ( 280 )
The fertilizer-herbicide granule with effervescent agent coating was prepared to increase the herbicide release rate. The effervescency of the granule enjoys a remarkable performance, which was evaluated with the methylene blue spectrophotometric method. The experiments revealed the release kinetics of mefenacet and bensulfuron-methyl (BSM) in the granule. The results show that the release equilibration time of mefenacet and bensulfuron-methyl in the effervescent granule is 15 and 11min, respectively, 33.3% and 36.7% of that in the common fertilizer-herbicide granule. The release kinetics of mefenacet and bensulfuron-methyl follows the dual constant equation and Logistic equation, with a correlation coefficients highly significant (P< 0.001). Their release rates are controlled by the Boyd film diffusion model and the Kannan-Sundaram intraparticle diffusion one.

Water-drive Mechanism with Nuclear Magnetic Resonance Technology

XIONG Wei;ZHU Zhiqiang;GAO Shusheng;HU Zhiming;DING Kun
Science & Technology Review. 2011, 29 (26): 34-37. ;  doi: 10.3981/j.issn.1000-7857.2011.26.004
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Abstract ( 406 )
The conventional core analysis conducted interiorly usually could not give the oil flowing performance in the process of water-flooding and the distribution of residual oil at the end of water-flooding. However, with Nuclear Magnetic Resonance (NMR) T2 relaxation spectrum, the oil movement in porous media and the distribution of remaining oil could be directly observed. Some core samples which had different permeability levels were chosen to conduct displacement experiments. The results show that for the cores with low permeability, the oil in the big pores will be displaced easily and the breakthrough recovery is high. Increasing displacement pressure is also able to further enhance the final oil recovery. Therefore, in the development process of these reservoirs, injecting water will be reasonable and realistic and is able to obtain better result. However, exorbitant displacement pressure might change the distribution of residual oil, that is, some parts of oil will be driven into the smaller pores and will become harder to be developed in the future. When the experiments have been completed, some of oils are still found in all sizes of the pores, including the big ones. For the cores with ultra-low permeability, breakthrough recovery is very low compared with the cores with low permeability. Therefore, water-flooding displacement is no longer an efficient development mode for these reservoirs. Oil field needs some other techniques, such as acidifying treatment, fracturing work, etc to assist the development of the cores with ultra-low permeability.

Intelligent Identification of Rock Mass Stability Based on the Fractal Characteristics of Rock Joints

SHEN Yan;LI Xibing;LIU Zhixiang
Science & Technology Review. 2011, 29 (26): 38-42. ;  doi: 10.3981/j.issn.1000-7857.2011.26.005
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Abstract ( 349 )
The fracture data of ore and rock joints are analyzed on the basis of plentiful interior mines geological survey information. And fractal characteristics of spacing and orientation distribution of rock mass joints are showed by using the fractal theory. In order to find the new methods for rock mass discrimination, an intelligent identification model, which embodies the relations among rock mass stability and uniaxial compressive strength, uniaxial tensile strength, internal friction angle, cohesion force, elastic module, fractal dimension of rock joints spacing, and fractal dimension of occurrence distribution, is established by using the neural network based on chaos optimization algorithm. Fractal dimensions of rock joints spacing and occurrence distribution that embody the all-distributing information of rock mass are showed as follows: The lower the fractal dimension value of joints spacing is, the better the rock mass integrity is. And the lower the fractal dimension value of orientation distribution is, the smaller the joints dispersion degree is. It means that the lower the both of fractal dimension values are, the better the stability of rock mass will be. According to rock mechanics parameters and joints fractal characters, rock mass stability under different geological conditions could be predicted; and a basis for engineering supporting design and construction could be provided by using the intelligent identification model.

Polarization Measurement and Calibration Technologies of Instantaneous Polarimetric Radar

WANG Xuesong;CHANG Yuliang;LI Yongzhen;DAI Huanyao;HE Mi;XIAO Shunping
Science & Technology Review. 2011, 29 (26): 43-49. ;  doi: 10.3981/j.issn.1000-7857.2011.26.006
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Abstract ( 288 )
As the most advantage measurement method nowadays, the Instantaneous Polarization (IP) measurement technology becomes one of the hot spots in the research field of polarimetric radar. Aiming at the measurement error of the traditional IP measurement technology, a new measurement method based on ambiguity function matrix is introduced. The measurement error caused by the nonorthogonality of the transmitting signals is eliminated by this method. The signal processing flowchart of the method is given. In order to resolve the problems involving the traditional polarization calibration technologies, such as implementation difficulty and low accuracy, the calibration method using single mental sphere is given. The availability of these methods is verified through the field test conducted by the IP radar system, KD-IPR.

Rib Stiffener Distribution and Ultimate Strength of Steel Tubular Tower's K-joint

HU Xiaoguang;YANG Jingbo;LI Maohua;ZHU Binrong;GAO Yuan
Science & Technology Review. 2011, 29 (26): 50-56. ;  doi: 10.3981/j.issn.1000-7857.2011.26.007
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Abstract ( 432 )
The K-joints of the cup type steel tubular tower in Ultra High Voltage (UHV) transmission lines are nuder the most complex loads. The angle θ between K-joint's chord and brace is usually less than 30°, while the method of calculating K-joint's ultimate strength in Chinese current "Code for design of steel structures" GB 50017—2003 requires that, θ must be no less than 30°. To deal with this problem, a general finite element software-ANSYS is used for its numerical simulation. The applicability of the current designing and calculating method is checked by the result of the simulation. 3 kinds of new rib stiffeners for directly-welded K-joint of steel tubular tower are designed. And the stress distribution and the ultimate strength of the new stiffeners are compared. It is shown that, if θ goes beyond the limit of the criterion, the calculating method in the code would fail for some engineering cases. With the new-designed rib stiffener, the stress distribution in K joint's dangerous area is improved obviously with the stress concentration eliminated and the maximum stress lowered. It is suggested that, the current code should be kept in use, because there is not a suitable alternative at the present. And the designed rib stiffeners should be adopted to increase the ultimate strength and security of the structure.

Impact of Transient Current and Ground Potential Rising on PC in Lightning Risk Assessment

YANG Zhongjiang;YU Shuyu;CHENG Bin
Science & Technology Review. 2011, 29 (26): 57-60. ;  doi: 10.3981/j.issn.1000-7857.2011.26.008
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Abstract ( 593 )
IEC 62305 proposed by the International Electrotechnical Commission is most commonly used. In IEC 62305, parameter PC is defined as follows: the probability of system failure is due to buildings stroking by the lighting. The parameter depends on the protection level of Surge Protective Device (SPD). However, when lightning strokes buildings, the lightning current in steel will produce electromagnetic interference on the internal system. And when the current runs into the earth, there is a high ground potential increase. In this case, SPD will not work well. Therefore, the definition of PC is no longer appropriate. Transient calculation models when lightning strokes metal frame of buildings have been proposed. However, no one has applied them to the study of lightning risk assessment. Here, a transient calculation model with Matlab is established to figure out transient current distribution in steels of the buildings when they are stroked by lightning and to calculate the back voltage due to ground potential rise. Under a certain approximate conditions, the effect due to lightning strokes buildings and the current goes into the earth on internal system is analyzed. Using the previous data, a clear physical model is set to show what factors affect the internal system most when lightning strokes buildings or the current goes into the earth. It is able to find that wiring mode and the installation of metal tube are the important parameters having the effect on the value of PC. Finally, by means of determining the factor that affects the parameter of PC and improving the parameter value, the value of lightning risk is accurately calculated with this method. The design of lightning protection and the planning of lightning protection are scientifically guided by the method.

Development and Application of CNC Milling Machine for Processing Long Special Shaped Spiral Rod

SHEN Xiaolong;ZHANG Laixi;HU Jiaying
Science & Technology Review. 2011, 29 (26): 61-66. ;  doi: 10.3981/j.issn.1000-7857.2011.26.009
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Abstract ( 318 )
The special shaped spiral rod can not be machined on a universal CNC lathe or a milling machine because its pitch and the bottom diameter vary with the angle. In this paper, a new type special CNC milling machine for processing long special shaped spiral rod is designed with the FANUC 0i-MC CNC system with the horizontal structure. The CNC milling machine is of three-axis linkage. The rotation of the workpiece is driven by axis c, and the milling feed is provided by the Alternating Current (AC) servo motor on the axes x and z. The AC frequency conversion stepless adjustment is adopted to control the rotation speed of the milling spindle. It is shown that the new machine has a wide range of practical engineering applications in view of improving the productivity and machining quality for processing special shaped spiral rod, and extending the functions of CNC milling machines.

Analysis of Academic Periodicals in Area of Public Health and Preventive Medicine in China

HONG Qi;DING Jinyu;WANG Xiaoyu;ZHOU Zhijun
Science & Technology Review. 2011, 29 (26): 67-73. ;  doi: 10.3981/j.issn.1000-7857.2011.26.010
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Abstract ( 364 )
To analyze the present state of academic periodicals on public health and preventive medicine in China, 73 academic periodicals in the area of preventive medicine and public health were selected from China National Knowledge Infrastructure (CNKI) and Wanfang Data Knowledge Platform. The major sources of data come from the periodicals, CNKI, China Academic Periodicals Web, China Citation Database, China Academic Periodicals Analysis Platform, and Chinese Academic Journals Comprehensive Citation Report 2008 (Beijing: Science Publisher). The 1980s is a period that saw the fastest growth in the number of periodicals, with growth rate over 200%. 43.8% of the editorial offices are located in the North China, 27.4% in Beijing. Most periodicals are published bimonthly (49.3%) while 4 are published semimonthly or once every ten days (5.47%). 23% of the periodicals are sponsored by Chinese Preventive Medicine Association (CPMA). Most of them are of good quality in printing and other features. 24.3% of them have their own websites, 30.1% uses public websites, and 38.4% do not use websites at all. The average time between the submission and the publication of a paper is 178 days, which falls short of the requirement for national scientific periodicals. Electronic service is common and effective. 69% of the periodicals respond to readers' queries within 24 hours. The average bibliometric indices of the 73 preventive medicine periodicals are as follows: the total publication number 259, the impact factor 0.392, the total citation 742, the impact factor in the same year 0.043, and the cited half-life 4.2 years. From 2001 to 2007, the 4 main indices (impact factor, impact factor in the same year, cited half-life, web download) see an upward trend. As a conclusion, Chinese preventive medicine periodicals have been improved in quantity since the 50's of the last century. The editorial, printing and service qualities have been improved. In the last decade, the average bibliometric indices (citation factor and source factor) have been improved steadily. However, the differences of the indices among journals are significant. Compared with the overall quality of Chinese scientific periodicals, the levels of network information and open database of preventive medicine periodicals lag relatively behind and need improvement.
Reviews

Progress on Electrostatic Performances of Explosive

LI Zhimin;ZHANG Tonglai;YANG Li;ZHOU Zunning;ZHANG Jianguo
Science & Technology Review. 2011, 29 (26): 74-79. ;  doi: 10.3981/j.issn.1000-7857.2011.26.011
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Abstract ( 310 )
The electrostatic performance of an explosive is an important aspect to estimate its safety under the electrostatic discharge environment. Studies of electrostatic sensitivity and electrostatic accumulation play an important role to reduce accidents caused by electrostatic discharge. The progress on the field of electrostatic performances of explosive is reviewed in this paper. Some factors influencing the results of measurement of the electrostatic spark sensitivity of explosive are analyzed, and the relationship between the electrostatic spark sensitivity and the molecular structure is discussed in detail. Also, the mechanism of igniting explosive by electrostatic discharge is discussed. Moreover, the studies related with electrostatic accumulation are reviewed briefly, and a further discussion on the electrostatic protection is made. The measurements of electrostatic sensitivity and electrostatic accumulation are influenced by various factors, such as the condition of instruments, ambient temperature, relative humidity, the shapes and sizes of the explosive particles. So, a large deviation would be expected when the electrostatic performance is evaluated under different conditions and environments, and the results we obtained are not absolute, only a relative comparison. When investigating the relationship between the electrostatic performance and molecular structure, these data should be obtained under a same condition.
科技评论

Science & Technology Review. 2011, 29 (26): 80-80. ;  doi:
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主编心语

Science & Technology Review. 2011, 29 (26): 83-83. ;  doi:
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走向职场

Science & Technology Review. 2011, 29 (26): 86-86. ;  doi:
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