Loading...

Table of Content

    25 December 2009, Volume 37 Issue 12
    Previous Issue    Next Issue
    Materials Science & Technology
    Preparation of TiO2-SiO2 Composite Powders Stabilized at High Temperature by Two-Step Hydrothermal Method
    Fang Pei-yu Wu Jian-qing
    2009, 37(12):  1-6. 
    Asbtract ( 527 )   PDF (430KB) ( 861 )  
    Related Articles | Metrics

    :TiO2-SiO2 composite powders stabilized at high temperature with high photocatalytic activity were prepared using a two-step hydrothermal method, with tetrabutyl titanate and tetraethyl orthosilicate as the materials. The powders were then characterized by means of dynamic light-scattering size analysis, DSC, FT-IR, TEM and XRD. The results of particle size analysis indicate that the composite powders disperse well in a size range of 10 - 30 nm with narrow distribution. DSC results show that the addition of silica greatly improves the high-temperature stability of titania dioxide. Phase analysis results demonstrate that the high-temperature stability of anatase titania becomes better with the increase of SiO2 content, and that the composite powders with a TiO2-SiO2molar ratio of 1 ： 1 maintain as anatase phase after being treated at 1200 ℃for 2h. FT-IR spectra show that there is no Ti-O-Si bonds in the.TiO2-SiO2 composite powders before and after the treatment at 800℃ for 2 h. Moreover, according to the degradation of aqueous methyl orange by TiO2-SiO2 composite powders under UV irradiation, it is found that （ 1 ） the photocatalysis of the composite powders without heat treatment is similar to that of commercial P25 TiO2 powders ; （2） the photocatalytic activity of the composite powders after the heat treatment at 800 and 1 000 ℃for 2 h is much higher than that of P25 ; and （3） after the heat treatment at 1200 ℃ for 2 h, the photocatalytic activity of the composite powders becomes poorer.

    Fabrication of Fiber Probes Using Improved Turner Method
    Wang Zhou-feng Huang Li Gao Ai-mei Deng Wen-li
    2009, 37(12):  7-11. 
    Asbtract ( 574 )   PDF (365KB) ( 810 )  
    Related Articles | Metrics


    Fiber probes for near-field scanning optical microscope were fabricated using the improved Turner method. Then, the morphology of the probes affected by such parameters as the environment factor and the characteristics of the etchant and the cover layer was investigated and compared with that of the probes fabricated via the tube etching. Moreover, the process of the Turner method was modified. The results indicate that （ 1 ） the reaction speed greatly increases with the reaction temperature, and an temperature increase from 0℃ to 32℃ may accelerate the reaction by 1.6 times ; （2） with the increase of etching solution concentration, the taper length becomes shorter and the surface becomes rougher; （3） a suitable long reaction time may increase the taper angle of the probes; （4） the rough honeycomb taper surface of the probes is due to the inherent limitation of the taper-forming process; and （5） a second etching effectively smoothes the taper surface and enlarges the taper angle.

    Composition and Corrosion Composite Films Resistance of Molybdate/Silane on Galvanized Steel
    Lu Jin-tang Zhang Shuang-hong Kong Gang Che Chun-shan
    2009, 37(12):  12-17. 
    Asbtract ( 625 )   PDF (407KB) ( 1082 )  
    Related Articles | Metrics

    Two kinds of molybdate/silane composite films were prepared using a one-step method and a two-step one on hot-dip galvanized steel sheets, respectively. The chemical composition and corrosion resistance of the two composite films were then investigated by means of XPS, AES, neutral salt spray （NSS） test and Tafel polarization curve measurement, and were compared with those of single-layer molybdate and silane films. The results show that （ 1 ） both the two films are of the same double-layer structure, and the inner layer, similar to molybdate conversion film, mainly contains O, Mo, Zn and P, while the outer layer, similar to silane film, mainly contains C, O and Si; （2） the chemical composition of the composite films gradually changes from the film to the substrate and from the inner layer to the outer one; （3） as compared with the single-layer molybdate and silane films, the composite films are of an evidently-inhibited cathode polarization process, with a self-corrosion current decreasing to less than 1/5 of that of the single-layer films and a remarkably-improved corrosion resistance; and （4） the two-step method results in a corrosion resistance stronger than that of the conventional chromate passivation film, while the one-step method results in a slightly poor corrosion resistance which is close to that of the conventional chromate passivation film.

    Effect of High-Amylose Corn Starch on Structure and Properties of Poly （ε-Caprolactone） Tissue Engineering Scaffolds
    Wang Xue-yu Chen Ling Su Jian-yu Li Xiao-xi Yu Long
    2009, 37(12):  18-22. 
    Asbtract ( 666 )   PDF (370KB) ( 1027 )  
    Related Articles | Metrics

    :By using high-amylose corn starch to modify poly （ε-caprolactone） （PCL）, starch/poly （ε-caprolactone） （SPCL） tissue engineering scaffolds were prepared via the solvent casting/particulate leaching. Then, the molecular chain structure, crystallinity, hydrophilicity and cell compatibility of the modified scaffolds were investigated by means of FT-IR, XRD, dynamic contact angle measurement and cell compatibility test. The results show that the addition of starch with proper dosage may decrease the crystallinity and improve the hydrophilicity and cell compatibility of the scaffolds, and that the scaffold with a starch dosage of 30% is of the best cell adhesion, proliferation and activity;, which promises to be applied to bone tissue engineering.

    Preparation and Properties of Comb-Branched Polyurethane/Polyisobornyl Acrylate Copolymerization Emulsion
    Chen Yong-jun Luo Yuan-fang Deng Xiang-hua Liu Fang Jia De-min
    2009, 37(12):  23-27. 
    Asbtract ( 662 )   PDF (330KB) ( 1042 )  
    Related Articles | Metrics

    :Comb-branched waterborne polyurethane/poly （ isobornyl acrylate ） （ CWPU/PIA ） copolymerization emulsion was prepared, with isobornyl acrylate （IBOA） as the monomer and with CWPU as the dispersant. Then, the effect of IBOA content on the properties of CWPU/PIA copolymerization emulsion was analyzed by means of FT-IR, TEM, particle size distribution and contact angle measurements. The results show that （ 1 ） the particles in CWPU/PIA copolymerization emulsion possess a core-shell structure with CWPU as the shell and with PIA as the core; （2） the particle size increases with the IBOA content; （3） at a IBOA content of less than 40%, the average particle size of CWPU/PIA copolymerization emulsion is below 150nm; （4） IBOA content has no obvious influence on the contact angle of CWPU/IBOA film, but it greatly affects the water absorptivity ; and （5） with the increase in IBOA content, the water absorptivity of the films decreases while the water resistance improves.

    Synthesis and Electrochemical Behaviour of Dendritic Amphiphilic Molecules with Ferroncenyl Substituents
    Ren Bi-ye Shi Lu Cheng Zhi-yu Shan Hua-zhong Li Chong-qing Tong Zhen
    2009, 37(12):  28-31,36. 
    Asbtract ( 496 )   PDF (296KB) ( 887 )  
    Related Articles | Metrics

    2,3,4-tri-（ l 1-ferroncenyl）decyl-l-yloxy benzoic acid was synthesized via the nucleophilic displacement reaction of methyl 3,4,5-trihydroxybenzoate and 11-ferroneenyl-l-bromoundecane. The compound was then characterized by means of elemental analysis, NMR, FT-IR and UV-Vis, etc. Moreover, the electrochemical behaviour of the compound was investigated using the cyclic voltammetry, the linear sweep vohammetry, the normal pulse voltammetry, the chronoampermetry and the chronocoulometry, and the electrochemical parameters of the compound were finally determined. The results indicate that the dendritic amphiphilie molecules in DMF solution exhibit good diffusion-controlled redox reversibility, and that the three ferroncenyl substituents of the compound do not interact strongly with one another but they exhibit similar redox activity.

    Autoclaved Performance of Solid Waste Containing Glass Phase
    Zhang Zhi-jie Tang Zheng-yu Ke Chang-jun
    2009, 37(12):  32-36. 
    Asbtract ( 492 )   PDF (331KB) ( 874 )  
    Related Articles | Metrics

    This paper investigates the autoclaved performance of the systems combining lime and such solid waste as fly ash, waste glass and slag by means of VF-IR, XRD and SEM. The results show that （ 1 ） at a saturated vapor pressure of 1.2 MPa, both the hydrothermal reactivity and the amount of combined water of the autoclaved product have an obvious negative correlation with the Si-O stretching vibration frequency; （2） the compressive strength of the autoclaved product containing fly ash or waste glass also has a negative correlation with the Si-O stretching vibration frequency; and （3） different from the other two products, the autoclaved product containing slag has a positive correlation with the Si-O stretching vibration frequency in terms of compressive strength, because there exists a large amount of hydrogarnet due to the reaction of activated Al in the slag with the lime.

    Investigation into Incineration Bottom Ash of Municipal Solid Waste Used as Cement Admixture
    Xie Yah Wu Xiao-mei Fan Yue-ming Yu Qi-jun Huang Jian Kuang Zhuo-rong
    2009, 37(12):  37-43. 
    Asbtract ( 668 )   PDF (532KB) ( 1258 )  
    Related Articles | Metrics

    The properties of cement with the incineration bottom ash of municipal solid waste as the admixture were investigated, and the environmental safety of the cement product was analyzed. The results show that （ 1 ） the bottom ash is an inactive admixture without radioactivity, which has no obvious influence on the cement soundness, the water consumption of standard consistence and the cement setting time ; （2） the compressive strength of the cement decreases with the increase of bottom ash dosage; （3） washed bottom ash has a relatively slight influence on the compressive strength; （4） a bottom ash dosage of 7.5% is suitable for the production of P ·O42.5 cement; （5） though the bottom ash has no obvious influence on the compatibility with superplasticizer, it reduces the shrinkage rate without arousing a steel corrosion; （6） at a bottom ash dosage of 15% -40% or 80%, the leaching limit of heavy metals in mortar reaches the standard of groundwater type Ⅲor type Ⅳ, respectively ; and （7） at a bottom ash dosage of 15%, the surface leaching of heavy metals in mortar also reaches the standard of groundwater type Ⅲ. It is thus concluded that the addition of bottom ash in cement does not bring about any harm to the environment and human health.

    Chemistry & Chemical Engineering
    Purification of CO via Selective Methanation Using Microchannel Reactor
    Dong Xin-fa Liu Wen-yue Gao Jun Lin Wei-ming
    2009, 37(12):  44-48,69. 
    Asbtract ( 598 )   PDF (413KB) ( 750 )  
    Related Articles | Metrics

    In order to effectively remove the small-quantity CO in hydrogen-rich reformed gas, 4Ni-2Ru/ZrO2 bimetallic catalyst was homogeneously coated on a microchannel reactor, and the method of selective methanation was used to purify CO. Then, the effects of calcination temperature, coating method, CTAB/Zr molar ratio and space velocity on the catalyst performance were investigated. Experimental results show that （1） when the calcination is performed at 350 ℃ after each slurry loading with a CTAB/Zr molar ratio of 0.35 and with a space velocity of 14286 h- 1, 4Ni-2Ru/ZrO2 catalyst is of excellent performance in low temperature, and the volume fraction of CO at the outlet reduces to 0. 0013 % at 260 ℃; and （2） a space velocity of 13000 -20000 h- 1 is suitable for the catalyst calcined at 350 ℃ after each slurry loading with a CTAB/Zr molar ratio of 0.35

    Optimization of Plasma Electrolytic Oxidation Process and Corrosion Resistance of Oxide Coatings
    Chen Li Peng Jia-zhi Yan Zong-cheng Wang Hong-lin Wang Li
    2009, 37(12):  49-52. 
    Asbtract ( 657 )   PDF (294KB) ( 916 )  
    Related Articles | Metrics

    :In order to optimize the plasma electrolytic oxidation （PEO） process of AZ31 magnesium alloy and investigate the corrosion resistance of the prepared ceramic coatings in terms of electrochemical kinetics, the Taguchi method was used to perform an orthogonal test in terms of four factors （namely, Na2SiO3 concentration, KOH concentration, electrolytic oxidation voltage and time） and three levels, and the corrosion resistance of the PEO ceramic coatings was evaluated by scanning the potentiodynamic polarization curve. It is found that the three levels in the Taguchi orthogonal array all significantly influence the corrosion resistance, and KOH mass concentration is a major affecting factor; and that, when the PEO is performed with 20g/L Na2SiO3 and 4g/L KOH at 300 V for 40rain, the ceramic coatings are of the highest corrosion resistance.


    Compound Heat Transfer Enhancement by Parallel Converged-Diverged Plate Inserted with Twisted Tapes
    He Zhao-hong Deng Xian-he Guan Zhi-zhang Li Zhi-wu
    2009, 37(12):  53-57. 
    Asbtract ( 525 )   PDF (356KB) ( 907 )  
    Related Articles | Metrics

    :In order to analyze the heat transfer performance of a new type of heat exchanger, namely, the rectangular tube-bundle heat exchanger, the characteristics of heat transfer and flow resistance of two parallel converged-diverged plates inserted with twisted tapes were experimentally investigated, and the results were then compared with those of smooth plates as well as with those of the parallel converged-diverged plates without twisted tapes. It is found that, when the Reynolds number varies from 19000 to 44000, both the local Nusselt number and the friction factor decrease with the increase of the distance from the tape tail, while the efficiency index of heat transfer enhancement first increases and then decreases; and that, when the Reynolds number is 19071 and the distance from the tape tail is 140mm, the efficiency index reaches the maximum, which is 15% and 9% higher respectively than that of the smooth plates and that of the parallel converged-diverged plates without twisted tapes. It is thus concluded that the parallel converged-diverged plates inserted with twisted tapes greatly enhance the heat transfer.


    Integration Analysis of LNG Cold Energy Utilization in Cryogenic Pulverization of Waste Rubber
    Xiong Yong-qiang Hua Ben Li Ya-jun Jia De-rain
    2009, 37(12):  58-63. 
    Asbtract ( 697 )   PDF (461KB) ( 1152 )  
    Related Articles | Metrics

    In order to reduce energy consumption in the production of fine rubber powders through the cryogenic pulverization of waste rubber, two integration techniques concerning LNG （Liquefied Natural Gas） cold energy utilization, namely the crushing under liquid nitrogen freezing and the cryogenic pulverization with cold nitrogen refrigeration, were proposed and then analyzed in terms of energy utilization. The results show that （ 1 ） with the utilization of LNG cold energy in the production of liquid nitrogen, the energy consumption decreases by 60. 2%, the power consumption reduces by 244. 3kW ·h per ton of LNG, the exergy efficiency reaches 60.7%, and the energy consumption of fine rubber powder production reduces by 126. 4 kW·h/t ; and （ 2 ） if the cryogenic crushing devices of waste rubber are adjacent to LNG terminals and if the by-produced cold nitrogen recovering LNG cold energy is provided for rubber powder plants to refrigerate and crush waste rubber, the energy consumption reduces by 437. 3 kW · h/t, as compared with the traditional air freezing method, the power consumption decreases by 276.3 kW · h per ton of LNG, and the exergy efficiency of LNG cold energy utilization is up to 70.7%.

    Rapid Determination of Ethyl Acetate Content via UV-Vis Spectroscopy
    Zhang Jun-hua Lin Lu Zhang Bei-xiao
    2009, 37(12):  64-69. 
    Asbtract ( 610 )   PDF (1059KB) ( 1032 )  
    Related Articles | Metrics

    :A rapid and effective determination method of ethyl acetate （EA） content is helpful for the determination and optimization of EA production technology. This paper proposes a rapid determination method of EA content based on UV-Vis spectroscopy, and verifies the accuracy of the method using a sample derived from the reaction of butanone and hydrogen peroxide. It is found that （ 1 ） the carmine complex derived from the color reaction of EA, hydroxylamine-HCl ethanol and FeCl3 is of the maximum absorption at 530 nm; （2） by establishing the linear relationship between the absorbance difference at 530 nm and 800 nm and the EA content via the dual-wavelength spectrophotometry, EA content can be successfully quantified; （3） this simple and low-cost method is of reasonably good precision when the color reaction is performed at a FeCl3/EA molar ratio of not less than 1.1 in a 100℃boiling-water bath for 40 s, and when the detection of UV spectroscopy is finished within 60 s ; and （4） the content determination error and recovery of EA derived from the reaction of butanone and hydrogen peroxide reach 1.79% and 95.5% - 105.0%, respectively.

    Fractal Analysis of Pore Structure of Eucalyptus Pulp Fibers
    Guo Wen-fie Wan Jin-quan Ma Yong-wen Wang Yan
    2009, 37(12):  70-74，80. 
    Asbtract ( 660 )   PDF (388KB) ( 993 )  
    Related Articles | Metrics

    The pore structure of eucalyptus pulp fibers was investigated by means of atomic force microscopy （AFM） and low-temperature nitrogen adsorption. Then, based on the fractal theory, the pore structure was further analyzed. AFM observation indicates that the eucalyptus pulp fibers are of a pore structure with self-similarity, which can be analyzed based on the fractal theory. Low-temperature nitrogen adsorption measurement shows that the fibers are of pore surface, and that the pores are mainly in a mesopore range, with an average size of 4. 9 nm, a BET specific surface area of 4. 83 m2/g and a total pore volume of 0. 005 8 cm3/g. Moreover, fractal analysis and calculation indicate that the pore structure of the fibers is of obvious fractal property in a dimension of 2.82, which means that the fibers are of rough and pore surface. It is also found that the fractal dimension of eucalyptus pulp fibers closely relates to the macroscopic properties such as water retention value.

    Structure and Characterization of Mechanically Activated Bagasse
    Huang Zu-qiang Gao Li Liang Xing-tang Hu Hua-yu Tong Zhang-fa
    2009, 37(12):  75-80. 
    Asbtract ( 607 )   PDF (424KB) ( 1159 )  
    Related Articles | Metrics

    :Bagasse was mechanically activated using a self-designed stirring-type ball mill, and the effects of mechanical activation on the surface morphology, crystal structure, functional groups of bagasse were characterized by means of SEM, XRD and FT-IR. The results show that （ 1 ） after the mechanical activation, the particle size of bagasse remarkably decreases, the crystal structure of bagasse fibers are destroyed, and the amorphous region enlarges due to the loading of mechanical force ; （2） both the crystallinity and the grain size of bagasse celluloses decrease after the mechanical activation, and an activation for 2.0 h may result in the crystallinity declines from 61.6% to 43.4% as well as the grain size of 002 plane decrease from 2. 243 nm to 1.512 nm; and （3） during the mechanical activation, no new functional groups are generated and the crystal type remains as cellulose Ⅰ

    Crystal Structure and Fungicidal Activity of N- （4,6-Dimethylpyrimidin-2-yl） Aniline Chloroacetate
    Li Jia-cheng Qiu Xue-qing Yang Dong-jie Lin Qiang
    2009, 37(12):  81-84. 
    Asbtract ( 636 )   PDF (303KB) ( 804 )  
    Related Articles | Metrics

    In order to obtain a high-activity pyrimidine fungicide, a new compound N-（4,6-dimethylpyrimidin-2- yl） aniline chloroacetate was synthesized via the reaction of pyrimethanil and ehloroaeetic acid in anhydrous ethanol and was then identified by means of elemental analysis, IR and 1H NMR. Moreover, the crystal structure of the compound was determined via single-crystal XRD, and the fungicidal activity was finally measured. The results indicate that （ 1 ） the crystal is monoclinic in a space group of P4 （2）/n, with the crystal parameters being as follows ： a = （1. 9604 ±0.0004） nm, 6 = （1. 9604 ±0. 0004） nm, c = （0.7542±0. 0003） nm, β =90°, V= （2. 8986 ± 0. 0013） nm3 ,De = 11324g· cm3, Z =8, F（000） = 1232,μ =0.27mm-1 ; （2） in the compound crystal, ehloroacetate anions are linked to N-（4,6-dimethylpyrimidin-2-yl）-aniline cations via N-H…O hydrogen bonding; （3） within the cations, the pyrimidine ring is twisted with respect to the phenyl ring in a dihedral angle of （7.59 - 0.04） °; and （4） the synthesized compound is of high fungicidal activity.

    Investigation into Pot Life of Waterborne Two-Component Polyurethane Coatings
    Kong Xia Luo Chun-hui Qu Jin-qing Chen Huan-qin
    2009, 37(12):  85-89，94. 
    Asbtract ( 618 )   PDF (401KB) ( 1035 )  
    Related Articles | Metrics

    Waterborne two-component polyurethane （2K-WPU） coatings were prepared from hydrophilically-modifled polyisocyanate reacting respectively with an aqueous hydroxy-polyacrylate emulsion （PAE） and its dispersion （PAD）. Then, the viscosity, hardness, gloss and chemical resistance of the films were measured to investigate the physicochemical behaviours of 2K-WPU during the storage. The results indicate that （ 1 ） with the increase of storage time, the viscosity of PAD-based 2K-WPU slowly decreases, along with an increase in bubbles and micro-foams in the film, the film hardness first decreases and then increases, and the chemical resistance decreases after a storage for 3h; （2） as for PAE-based 2K-WPU, the viscosity disorderly changes, the film hardness gradually decreases, the chemical resistance decreases after a storage for 4 h, and the bubbles in the film even disappear; （3） neither the particle diameter nor the gloss of PAE- and PAD-based 2K-WPU shows obvious change during the storage; and （4） PAD-based 2K-WPU is of better film performance but slightly shorter pot life than the PAE-based one （about 4 h）. It is thus concluded that it is not the viscosity but the chemical resistance and appearance of the film that determine the pot life of 2K-WPU before the application.

    Biological Engineering
    Enzymatic Synthesis of 2-Chloro-1-Phenylethanol with High Optical Purity
    Xia Xiao-le Wang Yong-hua Li Wen-cheng Yang Bo Wang Xiao-ning
    2009, 37(12):  90-94. 
    Asbtract ( 2191 )   PDF (352KB) ( 95611 )  
    Related Articles | Metrics

    Two enantiomers of chiral 2-chloro-1-phenylethanol with high optical purity were synthesized using the enzymatic method, and the kinetic resolution of various lipases were investigated. Moreover, the effects of organic solvent, temperature and water activity on the lipase-catalyzed resolution of （R, S）-2-chloro-1-phenylethanol were analyzed, and the reuse of immobilized enzymes was investigated. The results indicate that a new immobilized lipase from Pseudomonas cepacia marked as Lipase PS IM shows high activity, by which two high-purity enantiomers （eep 99% and ees 99% , respectively） can be separated in n-hexane at 35℃with a water activity of 0. 69; and that the relative activity of Lipase PS IM after five repetitive reactions is still up to 85%.

    Optimization of External Force of AEI-Cardiopulmonary Resuscitation Based on Simulated Annealing Algorithm
    Xu Lin Wu Xiao-ming Zhang Yan-ru Yuan Heng-xin
    2009, 37(12):  95-99. 
    Asbtract ( 644 )   PDF (372KB) ( 949 )  
    Related Articles | Metrics

    Active compression-decompression cardiopulmonary resuscitation （CPR） with enhanced external counterpulsation and inspiratory impedance threshold valve, namely, AEI-CPR, helps to achieve excellent hemodynamic effect. However, the resuscitation effect is subjected to the influence of the external force. In this paper, an efficient algorithm for NP complete combinatorial optimization problem, namely, simulated annealing algorithm, is used to optimize the control parameters of the external force for AEI-CPR based on an established mathematical model, with the average coronary perfusion pressure as the objective function. Optimization results show that optimal hemodynamic effect can be achieved when the maximum chest compression, chest decompression and lower limbs compression are respectively 438 N, 199 N and 390mmHg with a frequency of 102 min-1, and when the compression on calf, thigh and hip is in a time sequence of 0. 20, 0. 21 and 0.22 s.

    Hemodynamic Effects of a New Cardiopulmonary Resuscitation： Study with Computer Model
    Zhang Yan-ru Wu Xiao-ming Yuan Heng-xin Xu Lin
    2009, 37(12):  100-104. 
    Asbtract ( 614 )   PDF (349KB) ( 888 )  
    Related Articles | Metrics

    In order to digitalize a new cardiopulmonary resuscitation （CPR） called active compression-decompression CPR with enhanced external counterpulsation and inspiratory impedance threshold valve （AEI-CPR） , the hemodynamics of human body in the conditions of normal circulation, cardiac arrest and CPR were respectively simulated with computer model, and several CPR techniques, such as the standard CPR （S-CPR） , the active compres- sion-decompression CPR （ACD-CPR） , the standard CPR with enhanced external counterpulsation （SE-CPR） , and the AEI-CPR, were compared via simulation. The results indicate that （1） S-CPR generates a forward flow （FF） of 1.1 L/rain and a coronary perfusion pressure （CPP） of 30.2 mmHg, while those generated by ACD-CPR, SE- CPR and AEI-CPR are respectively 1.2 L/rain and 31.3 mmHg, 5.2 L/rain and 57.4 mmHg, and 5.6 L/rain and 57.6 mmHg ; （2） both the SE-CPR and the AEI-CPR greatly improve the forward flow ; and （3） AEI-CPR is of the best hemodynamic effect.

    Architecture & Civil Engineering
    Lamb＇s Problem for Unsaturated Soils Half-Space Under Vertical Concentrated Surface Load
    Xu Ming-jiang Wei De-rain He Chun-bao
    2009, 37(12):  105-110，117. 
    Asbtract ( 598 )   PDF (418KB) ( 842 )  
    Related Articles | Metrics

    Based on the mixture theory for porous medium, a group of dynamic governing equations for unsaturated soils is developed by introducing the bi-variable constitutive relations of soils. Then, with the help of Hankel integral transform, general solutions to axisymmetric problems are obtained in the frequency field, based on which the dynamic response of the unsaturated soils half-space subjected to a vertical concentrated surface load is investigated. Moreover, the integral solutions to Lamb＇s problem are obtained, which, in the absence of water and gas, degrade to the known conventional ones to Lamb＇s problem for one-phase elastic medium. Numerical results show that （1） both the excitation frequency and the permeability coefficient have significant effects on the displacement of ground surface; （2） the displacement decreases with the increase in excitation frequency and with the decrease in permeability coefficient, but remains unchanged when the permeability coefficient decreases to a certain low value; and （3） the direct influence of saturation on displacement lies in the facts that the latter slightly decreases with the increase of the former.

    Shear Behavior of High-Strength Bolts Penetrated Through Concrete-Filled Thin-Wall Square Steel Tube Column with Ribs
    Zhang Yao-chun Gao Jing-feng Yao Qi-yu Wang Hai-ming
    2009, 37(12):  111-117. 
    Asbtract ( 638 )   PDF (485KB) ( 809 )  
    Related Articles | Metrics

    :In order to investigate the shear behaviors of the high-strength bolts penetrating through the concretefilled thin-wall square steel tube column with ribs in non-slip critical connections, four specimens were tested, finding that the adopted connection is capable of transferring the shear force loading on the bolt reliably. The experimental results were then analyzed and a calculation model for the penetrated high-strength bolt was established. Moreover, a formula to calculate the shear resistance of the bolt was put forward by considering the possible failure modes, which was finally used to calculate the shear resistance of the bolt. The calculated results accord well with the experimental ones.


    Reliability of Simulation of Auditorium Acoustics
    Wang Hong-wei
    2009, 37(12):  118-121. 
    Asbtract ( 615 )   PDF (294KB) ( 768 )  
    Related Articles | Metrics

    :In order to investigate the simulation reliability of auditorium acoustics, the similarity level of the simulated and the measured impulse responses was analyzed, and the effective durations of the music episode deriving from the convolution between various impulse responses and dry sound signals in the full and the middle frequency ranges were compared. Moreover, some subjective audio tests were conducted for the music episode after the filtering in the full and the middle frequency ranges. The results show that there is no obvious difference between the simulated and the measured impulse responses, and that the simulations in high and low frequency ranges are both of low reliability. It is thus concluded that, as error-free acoustic simulation in the full frequency range cannot be achieved as yet, the convolution of actual impulse responses is still an effective way to acoustic evaluation.

    Failure Time Prediction of Slope Collapse of Block Rockmass Based on Gray and Catastrophic Theories
    Tian Qing-yan Fu He-lin
    2009, 37(12):  122-126. 
    Asbtract ( 592 )   PDF (306KB) ( 1185 )  
    Related Articles | Metrics

    In order to effectively predict the failure time of slope collapse of block rockmass, a gray-catastrophic prediction model is proposed based on the gray and the catastrophic theories. In this model, the monitored acoustic emission information is changed into prediction data based on the gray theory, and the prediction data are transformed into an essential format of cusp catastrophic model via the least-square principle curve fitting and the differential coefficient homeomorphous change. The proposed model is then used to predict the failure time of k79 ＋ 380 - k79 ＋ 500 right slope of Gui-Bi highway, and the predicted results basically accord with the actual ones. It is thus concluded that the proposed model is effective in predicting the failure time of slope collapse of block rockmass.

    Transverse-Isotropic-Elastic Homogenization Model of Pre-Support
    Wang Hai-bo Xu Ming Song Er-xiang
    2009, 37(12):  127-131，139. 
    Asbtract ( 554 )   PDF (360KB) ( 1097 )  
    Related Articles | Metrics

    As an important means of stratum stabilization and deformation control in tunnel excavation, the pre-support, including pipe-roofing reinforcement and small pipe grouting, should be properly simulated and analyzed, and how to establish a simple and reasonable model considering the overall effect is the key issue in the numerical simulation. For this purpose, this paper presents a transverse-isotropic-elastic homogenization model of pre-support and establishes a simplified model based on the average elastic properties of pre-support, which can be used to analyze the influences of some important parameters such as pipe distance and diameter. The proposed model is then applied to the 3D finite element simulation of a tunnel excavation, with its effectiveness being finally verified.

    Mechanics
    Nonlinear Dynamic Stability of Functionally Graded Cylindrical Shells Under Step Loads
    Huang Huai-wei Han Qiang
    2009, 37(12):  132-139. 
    Asbtract ( 620 )   PDF (473KB) ( 809 )  
    Related Articles | Metrics

    This paper deals with the nonlinear dynamic buckling of functionally graded cylindrical shells under axial and lateral step loads. In the investigation, a nonlinear dynamic equilibrium equation is deduced using an energy method and is then solved by means of the four-order Rugge-Kutta method with various step lengths. Thus, the response curves of the shell structure are derived, which are combined with the B-R dynamic buckling criterion to determine the critical buckling condition. Numerical results show that （ 1 ） there is a dominating mode of structural deformation under step loads, which aroused the earliest structural response with maximum amplitude; （2） in the case of axial and lateral step loads, the nonlinear dynamic buckling loads are quite close to the corresponding linear static ones; （3） under axial step loads, the dynamic load would inspire a buckling mode with higher order; （4） the dynamic buckling load of the structure increases with the content of ceramic constituent ; and （5） the critical load in the linearly-distributed temperature field is close to that in the actual thermal-conduction temperature field.

    Test and Simulation of Cushioning Composite- Laminated Energy-Absorbing Property of Cylindrical Shells
    Song Yi Wang Fan
    2009, 37(12):  140-145. 
    Asbtract ( 656 )   PDF (424KB) ( 4741 )  
    Related Articles | Metrics

    :According to the kinetics of composite-laminated cylindrical shells subjected to axial impact loads, the cushioning energy-absorbing property of the standard and the petal-triggered GFRP （Glass Fiber-Reinforced Composite）-laminated cylindrical shells are investigated through the quasi-static compression test. Then, by setting up a material model which implements the Chang-Chang failure criterion, the dynamic response process of the shells under drop impact is simulated using ANSYS/LS-DYNA. The simulated results of the normal composite-laminated cylindrical shells accord well with the experimental ones in terms of some key characteristics, and the simulation errors of velocity, displacement, acceleration and peak acceleration are found to be 19.5%, 12. 0%, 6. 4% and 14. 6%, respectively. Moreover, the improvement of triggering mode of the petal-triggered composite-laminated cylindrical shells increases the specific energy-absorbing value, greatly decreases the initial peak load, and prolongs the compression displacement for the peak load. It is thus concluded that the model based on the Chang-Chang failure criterion helps to precisely predict the crushing process and the failure of the material.

    SPH-Based Numerical Simulation of Aircraft Windshield Under Bird Impact
    Li Zhi-qiang Han Qiang Yang Jian-lin Zhao Long-mao Yao Xiao-hu
    2009, 37(12):  146-151. 
    Asbtract ( 660 )   PDF (501KB) ( 991 )  
    Related Articles | Metrics

    Bird impact resistance of windshield is most important for flight safety. In this paper, based on the experimental observation of aircraft arc windshield under bird impact, a finite element analysis model of arc windshield and bird body for a certain aircraft made in China is established, and the impact process is numerically simulated by means of the Smoothed Particle Hydrodynamics （SPH） coupling with the finite element method. Then, a series of data such as deformation, displacement, strain, impact force, stress, critical impact velocity, possible damage location, and mode of arc windshield are obtained. Moreover, the effect of SPH particle density on the calculation results is analyzed. It is found that （ 1 ） the simulated results basically accord with the experimental ones ;（2） the whole process of bird impact lasts about 4ms, and the critical impact velocities of windshield damage （ including safety damage） are （540 ±5）, （600 ±5） and （470 ±5） km/h at the middle point, the front 1/3 and the back 1/3 of the windshield, respectively; （3） the displacement and thickness of windshield in the impact process are of the same order of magnitude, and the maximum strain of windshield reaches 10-2 order of magnitude; （4） the damage of windshield first locates near the back arc frame, then expands towards 45°direction with respect to the windshield midline ; and （5） the deformation mode of bird body becomes better with the increase of SPH particles.

News
 
More>>
Featured Article
More>>
Most Read
More>>
Most Download
More>>
Most Cited
More>>
Links
More>>