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Table of Content

    25 April 2010, Volume 38 Issue 4
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    Chemistry & Chemical Engineering
    Hydrophobic Modification of Pulp Fiber Surface via Layer-by-Layer Self-Assembly of Lignosulfonates
    Fu Shi-yu Li Hui Liu Hao Li Xue-yun Zhan Huai-yu
    2010, 38(4):  1-5.  doi:10.3969/j.issn.1000-565X.2010.04.001
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    Layer-by-layer（LbL） self-assembly of lignosulfonates（LS） and Cu 2＋ was applied to the hydrophobic modification of pulp fiber surface.The modified fiber surface was then characterized by means of X-ray photoelectron spectroscopy,atomic force microscopy（AFM） and dynamic contact-angle measurement.The results show that  the contents of S and Cu on fiber surface both increase with the alternate assembly of LS and Cu 2+ ,which veri-fies the feasibility of the LbL self-assembly of lignosulfonates on fiber surface ； the microfibrils on fiber surface are gradually and compactly covered by granular lignin particles during the process of self-assembly  the ave-rage phase of AFM phase images increases with the content of lignin on fiber surface,which suggests the improvement of the hydrophobicity of fiber surface  with the increase of self-assembly layers,the initial contact angle of fiber surface increases and the decline rate of contact angle decreases in a period of 0.08s;and  the initial contact angle increases from 0° to 104.8° after the fiber surface has been modified with five self-assembly layers,and then decreases to 78.9° after 0.08s,which means that the excessively hydrophilic fiber surface is modified to a hydrophobic one in a certain degree.It is thus concluded that the hydrophobic modification of fiber surface can successfully be implemented by controlling the number of assembled layers.

    Dissolving Rules of Saccharides During Hot-Water Preextraction of Bamboo
    Zhan Huai-yu Hu Hui-chao Fu Shi-yu
    2010, 38(4):  6-11.  doi:10.3969/j.issn.1000-565X.2010.04.002
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    This paper deals with the relationships between the H-factor and the dissolving rates of main saccharides,the ratio of total saccharides and pentose to the total solid as well as the concentration of furfural（F） and hydroxymethylfurfural（HMF） in the hot-water preextracted liquor of bamboo in different conditions.The results show that（1） for the purpose of obtaining more saccharides and reducing the conversion of saccharides to F and HMF,the lgH value during the preextraction should be controlled within the range of 3.2～3.4,and the maximum preextraction temperature should not be higher than 160℃;（2） when the lgH value is lower than 3.2,the dissolving rates of saccharides decrease,while when it is higher than 3.4,some saccharides convert to F and HMF,and the dissolving rates as well as the ratio of total saccharides and pentose to the total solid decrease;and（3） at the maximum dissolving rate and the same H-factor,more saccharides may convert to F and HMF at a higher temperature（160℃）.

    Ultrafiltration of Bamboo Pulp Black Liquor Modified by Graft Sulfonation and Water-Reducing Dispersion Performance of Fractions
    Lou Hong-ming Zhang Hai-bin Liang Qiao Yang Dong-jie Qiu Xue-qing
    2010, 38(4):  12-17.  doi:10.3969/j.issn.1000-565X.2010.04.003
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    Bamboo pulp black liquor modified by graft sulfonation（GCL1-JB） was fractionated into four fractions with different relative molecular mass（RMM） by ultrafiltration,and the RMM distributions of GCL1-JB fractions were characterized by means of GPC.Then,the effects of GCL1-JB fractions on the performances of fresh cement paste and mortar were analyzed.The results show that（1） the fraction with high RMM is of better water-reducing dispersion performance;（2） when the dosage of the fraction with high RMM（more than 50000） is 0.5%,the fluidity of cement paste reaches 287mm at a water to cement ratio of 0.29,the fluidity loss ratio reaches 7% after 120min,and the 3-day,7-day and 28-day compressive strength ratios of mortar are respectively up to 159.4%,193.4% and 143.8%;（3） the fraction with moderate RMM is of strong air-entraining and retarding effect,which improves the workability of fresh mortar,although the long-term compressive strength of hardened mortar is relative low;and（4） when the dosage of the fraction with moderate RMM（10000～50000） is 0.5%,the initial setting time and final setting time of cement paste prolong for 140 and 297min,respectively,and the 28-day compressive strength ratio of hardened mortar is up to 99.8%.

    Effects of Modification of Laccase/Mediator System on Refining Property and Fiber Morphology of Masson Pine TMP
    Peng Xin-wen Li Xin-ping Zhang Su-feng Ren Jun-li Sun Run-cang
    2010, 38(4):  18-22,29.  doi:10.3969/j.issn.1000-565X.2010.04.004
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    This paper deals with the refining property and fiber morphology of thermo-mechanical pulp（TMP） of masson pine modified with laccase/mediator system.The results indicate that,after the modification with laccase/mediator system,the middle lamella and even the primary wall of the fibers corrodes,the content of lignin on the fiber surface decreases,and more layer structure rich in carbohydrates are exposed to water.Thus,the water absorption of the fibers increases,the softness and swelling of the fibers improve,and the refining property improves to some extent.Moreover,it is found that the breaking length and tearing index of the paper sheet formed by the fibers with laccase modification increase by 37.30% and 47.33%,respectively,the bulk decreases by 20.33%,and the contact angle also decreases.It is thus concluded that the laccase modification is effective in improving the refining property of masson pine TMP and the strength of paper sheet.

    Effects of Deinking Mode on Pore Structure and Crystallization Property of Recycled Fiber
    Guo Wen-jie Wang Yan Wan Jin-quan Ma Yong-wen
    2010, 38(4):  23-29.  doi:10.3969/j.issn.1000-565X.2010.04.005
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    X-ray diffraction and low-temperature nitrogen adsorption were adopted to investigate the pore structure and crystallization property of the fibers of old newspaper pulp（ONP） and deinking pulp with different deinking modes,and the fractal geometry was used to further analyze the pore structure of the fibers.The results indicate that（1） the BET specific surface area,BJH pore volume and BJH average pore size of the deinking fibers remain almost unchanged after a neutral,alkaline or enzymatic deinking process;（2） the fractal dimensions of the fibers before and after the deinking process are similar,which means that deinking modes have little effect on the pore structure of the fibers;（3） the crystallinity of the fibers decreases to 12.24%,6.12% or 0.77% after a neutral,alkaline or enzymatic deinking process,respectively;（4） the water retention value（WRV） increases after deinking,in an order of alkali deinkingneutral deinkingenzymatic deinking;and（5） after deinking,the beating degree and average length of the fibers slightly decrease while the content of fine fibers increases.

    Thermodynamic Analysis of Synthesis of Ni 1/3 Co 1/3 Mn 1/3（OH）2 via Coprecipitation
    Xiao Xin-yan Ye Yong-qing
    2010, 38(4):  30-34,44.  doi:10.3969/j.issn.1000-565X.2010.04.006
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    The thermodynamic analysis of Me 2＋-NH3-OH--H2O（Me=Ni,Co,Mn） coprecipitation system was carried out,and the precursor Ni 1/3 Co 1/3 Mn 1/3（OH）2, for cathode material LiNi 1/3 Co 1/3 Mn 1/3 O2 was synthesized via a coprecipitation method,with NaOH as the precipitant and NH3·H2O as the complexing agent.The thermodynamic analysis shows that the optimal conditions are pH value of 11 and ammonia concentration 0.1～0.5mol/L,and the loss of Ni 2＋,Co 2＋ and Mn 2＋ reaches the minimum,that is,1×10 -3,1×10 -3 and 1×10 -6 mol/L,respectively.The molar ratio of Ni/Co/Mn in the synthesized precursor is 0.324∶0.349∶0.327,which approximates the desired 1∶1∶1,and the tap density of the synthesized precursor is up to 1.32g/cm3 when pH value is 11 and an ammonia concentration is 0.24mol/L.

    Synthesis of Ribavirin Derivatives
    Lin Dong-en Peng Yun-tie Zhang Yi-wei
    2010, 38(4):  35-39.  doi:10.3969/j.issn.1000-565X.2010.04.007
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    1-[5-（4-nitrobenzoy）-β-D-ribofuranosyl]-1,2,4-triazole-3-carboxamide（IIIa）,1-[5-（3,4,5-tribenzyl-oxybenzoyl）-β-D-ribofuranosyl]-1,2,4-triazole-3-carboxamide（IIIb） and 1-（5-benzoyl-β-D-ribofuranosyl）-1,2,4-triazole-3-carboxamide（IIIc） were synthesized from 1-[2,3-O-（1-methylethylidene）-D-ribofuranosyl]-1,2,4-triazole-3-carboxamide（I） through the esterification with three different acyl chloride catalyzed by base and the hydrolysis catalyzed by p-TsOH.Then,1-[5-（4-aminobenzoyl）-β-D-ribofuranosyl]-1,2,4-triazole-3-carboxamide（IVa） and 1-[5-（3,4,5-trihydroxybenzoyl）-β-D-ribofuranosyl]-1,2,4-triazole-3-carboxamide（IVb） were obtained by means of catalytic hydrogenation.Moreover,the intermediates and title compounds were confirmed by means of IR and 1H NMR,and the effects of different kinds of bases and solvents on the esterification,different kinds of acids on the deprotection reaction and Pd/C dosage on the catalytic hydrogenation were investigated.The results show that（1） the esterification,with pyridine as the acid-binding agent and the solvent,is of high yield and good selectivity,and the conversion rate is up to more than 95%;（2） p-TsOH is a suitable catalyst for the deprotection reaction with fewer by-products;and（3） the conversion becomes complete at a mass ratio of Pd/C to compound IIIa of 0.10.

    Mathematical Model Describing Through-Air Drying Process of Paper
    Wang Zheng-shun Chen Ke-fu Huang Liang-hui Kang Guo-bing
    2010, 38(4):  40-44.  doi:10.3969/j.issn.1000-565X.2010.04.008
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    Based on the air drying theory of porous media,a mathematical model describing the through-air drying（TAD） process of paper was built and numerically analyzed.Then,the reliability of the model was validated by hot-air drying experiments using a self-developed experimental device.The results show that the calculated paper moisture and temperature varying with the drying time accord well with the measured ones,and that,in the normal drying period and the decreasing period,the calculated values are only 4 percent higher than the measured ones.It is thus concluded that the proposed mathematical model and numerical calculation method are both reliable,which provides a theoretical basis for the design and operation optimization of TAD of paper

    Food Science & Technology
    7S-Rich Fractions Hydrolyzed by Alcalase and Functional Properties of the Hydrolysates
    Zhao Mou-ming Luo Dong-hui Zhao Qiang-zhong Long Xiao-tao
    2010, 38(4):  45-49.  doi:10.3969/j.issn.1000-565X.2010.04.009
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    Soy β-conglycinin-rich（7S-rich） fractions were hydrolyzed by alcalase,and the hydrolysates were investigated in terms of solubility,droplet size distribution of emulsion and heat-induced gelling properties.Moreover,the effect of the degree of hydrolysis（DH） on the functional properties of the hydrolysates was discussed.The results show that（1） the initial stage of enzymolysis,namely,the stage in the first 30min with a DH lower than 7.69%,constitutes a key stage for the formation of the functional properties of 7S-rich fractions;（2） at a DH of 4.53%,the solubility,emulsion activity and gelling property of the hydrolysates improve significantly;（3） at a DH of 4.53% and a pH value of 7.0,the solubility and elastic modulus improve by 27.3% and 158.15%,respectively,while the average droplet diameter of emulsions stabled by hydrolysates decreases to 0.936μm,which is only 4.55% of that of emulsions stabled by 7S-rich fractions;and（4） with the further increase in DH,both the emulsion activity and the gelling property show a downward trend.

    Physicochemical and Functional Properties of Polysaccharides from Soybean Hull and Okara
    Lai Fu-rao Wen Qi-biao Li Lin Wu Lei-yan Wu Hui Yu Yi-gang
    2010, 38(4):  50-54,60.  doi:10.3969/j.issn.1000-565X.2010.04.010
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    This paper deals with the physicochemical and functional properties of polysaccharides isolated from soybean hull（SHP） and soybean okara（SOP）.In the investigation,first,crude SHP and SOP were fractioned and purified,and three purified fractions were obtained from SHP or SOP.Then,the physicochemical properties of the two types of crude polysaccharides and the fractions were analyzed by means of GC and GPC,and the functional properties of the samples were discussed by emulsifying and bile acid binding experiments.The results show that SHP fractions are acid heteropolysaccharides without protein,the relative molecular mass of which is 45～150ku,while SOP fractions are glycosidoprotein with a relative molecular mass of 14～370ku;and that,as a water-soluble polysaccharide with excellent functional properties,SOP is superior to SHP in terms of emulsifying performance and in-vitro bile acid binding ability.

    Determination of Diameter Distribution of Starch Granules by FBRM
    Zhang Ben-shan Chen Fu-quan Zhao Yong-qing Gao Ling-yun Chen Cui-lan Lu Hai-feng Han Zhong
    2010, 38(4):  55-60.  doi:10.3969/j.issn.1000-565X.2010.04.011
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    In order to monitor the diameter change of starch granules in physical or chemical process on line,the influences of the starch slurry concentration,stirring rate and medium on the distribution of the granule diameter were investigated by means of FBRM.Moreover,the granule diameter distribution curves of different starches and the granule diameters of the same starch measured by different methods were analyzed.The results show that（1） with the increase of starch slurry concentration,the granule diameter measured by FBRM first increases and then decreases,and it reaches its maximum at a slurry concentration of 1%;（2） the stirring rate slightly affects the measurement of the granule diameter;（3） the granule diameter distribution becomes stable when ethanol and isopropanol with a concentration of lower than 50%,or glycerol with a concentration of higher than 75%,is used as the medium;（4） the distribution curves of the granule diameter vary with the starch type;and（5） even for the same starch granule,the measured diameter is inconstant due to different measurement methods.

    Effect of Operation Conditions on Purification of Unsaturated Monoglyceride via Molecular Distillation
    Zeng Fan-kui Wang Yong-hua Yang Bo Liu Hong Ning Zheng-xiang Li Lin
    2010, 38(4):  61-64.  doi:10.3969/j.issn.1000-565X.2010.04.012
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    Single-factor experiments and orthogonal tests were carried out to reveal the effects of such operation conditions as evaporation temperature（θe）,feed flowrate（Q）,feed temperature（θf） and condensation temperature（θc） on the mass ratio D/F of the distillate stream to the feed during the purification of unsaturated monoglyceride by molecular distillation,and an order of the operation conditions affecting the D/F value was found as θe〉Q〉θf〉θc.Then,two quadratic regression equations were established to predict the content of monoglyceride（MAG） and diglyceride（DAG） in the distillate stream at different evaporation temperatures.Moreover,to verify the reliability of the equations,some tests were performed respectively at the feed flowrate of 0.71,1.06,1.42mL/min and the evaporation temperature of 150～200℃,and the results were found to accord well with those predicted by the mo-del.Finally,the variation of unsaturated MAG recovery in the distillate stream with operation conditions was investigated.The results show that,at an θe of 170～190℃,a feed flowrate of 0.71mL/min,a θf of 70℃ and a θc of 60℃,the purity of MAG in the distillate stream is up to more than 80% only with a single-step molecular distillation,and the MAG recovery varies from 60% to 80%.

    Effect of Ageing Time of Paddy on Quality Characteristics of Rice Noodles
    Liang Lan-lan Zhao Zhi-min Wu Jun-hui Wu Qiu-ting Chen Jia-dong Ning Zheng-xiang
    2010, 38(4):  65-70，96.  doi:10.3969/j.issn.1000-565X.2010.04.013
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    This paper reveals the effects of ageing time of paddy on the characteristics of rice noodles such as textural properties,thermal properties,relative crystallinity of rice starch crystal and fatty acid value of paddy,and the relationships between the textural properties and the three other characteristics are discussed.The results show that the ageing time greatly affects the tension and shearing properties of rice noodles.When the ageing time prolongs,the maximum break stress,the shearing stress,the maximum break strain and the break work all increase.More-over,correlation analyses indicate that（1） there exist significant relationships between the break work of rice starch gel and the DSC start temperature,the peak temperature,the DSC peak area as well as the enthalpy（P〈0.05）,and between the peak height and the break wok（P〈0.01）;（2） the relative crystallinities of both sub-crystals and crystals are related not only to the maximum break stress of rice starch gel（P〈0.01） but also to the shearing stress and the break work（P〈0.05）;and（3） there is no significant relationship between the fatty acid value of paddy and the tension and shearing properties of rice noodles（P〉0.05）.

    Materials Science & Technology
    Effect of Porogen Morphology on Structure and Property of Calcium Phosphate Cement Scaffold
    Ye Jian-dong Luo Fang-cong
    2010, 38(4):  71-75.  doi:10.3969/j.issn.1000-565X.2010.04.014
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    Calcium phosphate cement（CPC） scaffolds with large porosities and high compressive strength were prepared for bone tissue engineering via the soluble salt-leaching method combined with the cold isostatic pressing treatment,with cubic sodium chloride and rod-like monosodium glutamate crystals as porogens,respectively.Then,the phase composition of the scaffolds was analyzed by XRD and the effect of porogenmorphology on the microstructure and mechanical property of the scaffolds was investigated by means of SEM and mechanical tests.The results indicate that（1） the major phase of the scaffolds prepared with the two above-mentioned porogens are both poorly crystalline hydroxyapatite;（2） the shape of macropores in the scaffolds depends on the porogen morphology that affects the porosity and mechanical property of the scaffolds;（3） with the same dosage of porogen,the porosity of the scaffold prepared with monosodium glutamate crystals is higher than that of the scaffold prepared with sodium chloride crystals,while the compressive strength is lower;and（4） the cold isostatic pressing treatment results in high compressive strength of the scaffolds.

    Influence of Additives on Ce-Mn Conversion Coating at Room Temperature
    Zhang Jun-jun Li Wen-fang Du Jun
    2010, 38(4):  76-82.  doi:10.3969/j.issn.1000-565X.2010.04.015
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    In order to accelerate the coating formation and improve the corrosion resistance of Ce-Mn conversion coating on aluminium alloy at room temperature,six additives including H3BO3,Zr（SO4）2,NaF,HF,NaBF4 and Na2ZrF6 were respectively added in the mixed solution of Ce（NO3）3 and KMnO4,and the effects of these additives on the behaviours of Ce-Mn conversion coating were investigated.Then,the metallographic structure and thickness of the coating were analyzed by using an optical microscope and an eddy current thickness meter,respectively,and the corrosion resistance of the coating was discussed by dropping corrosion test,Tafel polarization curves and electrochemical spectroscopy（EIS）.Finally,the effects of NaF on the morphology and composition of the coating were analyzed by means of SEM and EDS.The results indicate that,with the help of NaF,Ce-Mn conversion coating can be prepared at room temperature with a time consumption of only 9min,the thickness,anti-corrosion time,co-rrosion current density and impedance of the coating are respectively 3.3,3.0,1/3 and 4.9 times that of the coating without any additives,and the Ce and Mn contents of the coating increase from 5.14% to 8.59% and from 7.70% to 14.42%,respectively.It is thus concluded that NaF is an optimal additive for the formation of Ce-Mn coating.

    Synthesis and Catalytic Performance of Silicoaluminophosphate Molecular Sieves from Metakaolin
    Zhong Ming-feng Zhang Zhi-jie Zhou Xin-tao
    2010, 38(4):  83-86.  doi:10.3969/j.issn.1000-565X.2010.04.016
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    Silicoaluminophosphate（SAPO-5） molecular sieves were synthesized respectively by the piecewise and one-step crystalline methods,with metakaolin as the silicon and aluminum sources,phosphoric acid as the phosphorus source and with triethylamine combined with hexadecyl trimethyl ammonium bromide as the template agent.Then,the prepared molecular sieves were characterized by means of XRD,SEM,XPS and NH3-TPD analysis.The results show that the product prepared by the piecewise crystalline method is of uniform pillar-like morphology,large size（about 20μm×5μm×5μm）,proper P∶Al∶Si molar ratio（1∶1.19∶0.67）,high Si content and higher total acid content（578.0μmol/g）,and that its initial activity（24.8%） is much higher than that of the product prepared by the one-step method（14.1%）.

    Application of TiO2 Nanocrystalline to Dye-Sensitized Solar Cells
    Xu Yuan-mei Fang Xiao-ming Zhang Zheng-guo
    2010, 38(4):  87-91.  doi:10.3969/j.issn.1000-565X.2010.04.017
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    Rhombic TiO2 nanocrystallines,10～15nm in diameter and 112m 2/g in specific surface area,were prepared from P25 via the hydrothermal method.Then,porous TiO2 film was made from the nanocrystallines and were characterized by using a SEM and a N2 adsorption unit.The results were compared with those of the film made from P25.It is found that the TiO2 film is of narrow size and good dispersivity,and that its BET specific surface area and dye adsorption are both two times that of P25 film.Moreover,by analyzing the photoelectric properties of the dye-sensitized solar cells,it is concluded that the cell based on TiO2 film is superior to that based on P25 film because the former is of high photocurrent density and conversion efficiency.

    Cure Kinetics of Epoxy Resin System Used for Casting Dry-Type Transformer
    Li Zhi-qiang Han Qiang Liu Si-wei Liu Yan
    2010, 38(4):  92-96.  doi:10.3969/j.issn.1000-565X.2010.04.018
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    The cure kinetics of dynamic heating process of epoxy resin system used for casting dry-type transformer is investigated based on the nonisothermal DSC method,and the relationship between the curing degree and the preexponential factor as well as the activation energy is revealed by using the free model method.The results show that the curing of epoxy resin system is not a simple one-step reaction but a complex multi-step one.Then,the DSC data are nonlinearly fitted via the phenomenological model.The fitting results accord well with the experimental ones with a correlation of 99.51%,which means that the system complies with the n-level three-step branch reaction model.Finally,isothermal prediction for the system is performed by using the established phenomenological model.The results show that,at constant curing time,the curing degree and rate both decrease with the curing temperature.

    Architecture & Civil Engineering
    Analysis of Bending Moment of Restrained RC Columns in Heating and Cooling Process
    Wu Bo Qiao Chang-jiang
    2010, 38(4):  97-105.  doi:10.3969/j.issn.1000-565X.2010.04.019
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    With the help of SAFIR,the bending moment of reinforced concrete（RC） columns in the heating and cooling process is analyzed,and the influences of such parameters as sectional dimension,reinforcement ratio,heating time and rotational restraint stiffness ratio,etc.on the bending moment at the mid-height of restrained concrete column exposed to the ISO834 standard fire with cooling phase are investigated.The results are then compared with those corresponding to the ISO834 standard fire without cooling phase.Moreover,based on the simulation of 192 cases,a practical calculation method for the bending moment at the mid-height of column exposed to fire with cooling phase is proposed.It is thus shown that（1） the enhancement coefficient of the bending moment at the mid-height of axially-restrained column first increases and then gradually decreases till to a constant in the fire with cooling phase,which is quite different from that in the fire without cooling phase;（2） the enhancement coefficient of the bending moment at the mid-height of axially-and-rotationally-restrained column first rapidly decreases and then gradually decreases till to a constant in the fire with or without cooling phase;and（3） the proposed calculation method is of high accuracy,and the correlation coefficient between the calculated results and the simulation ones reaches 0.992.

    Wind-Induced Fatigue Analysis in Time Domain for Transmission Tower-line Coupling System
    Wang Zhi-song Li Zheng-liang Xiao Zheng-zhi Yan Zhi-tao
    2010, 38(4):  106-111.  doi:10.3969/j.issn.1000-565X.2010.04.020
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    The transmission tower-line structure under wind loads is a nonlinear coupled vibration system.Its members alternately undergo reversal stress due to the flutter component of the natural wind,which may result in the fatigue damage of the structure.In this paper,with a direct-current transmission line as a case,a method to analyze the wind-induced fatigue in time domain is proposed for the vibration of transmission tower-line system.Then,the random wind field is simulated by using the AR model,and the nonlinear time-history wind-induced vibration of the tower-line coupling system is analyzed.Moreover,an equation to calculate the fatigue cumulative damage affected by the distributions of wind direction and speed is established,and the dangerous members with potential fatigue cumulative damage are determined,followed by a detail stress analysis.Finally,the fatigue life of the members under wind loads is estimated based on the linear cumulative damage theory.It is found that the proposed time-domain analysis method can effectively estimate the residual life of the transmission tower in wind-induced vibration.

    Ultimate Bearing Capacity of Steel Tube-Gusset Plate Connections Considering Negative Eccentricity
    Liu Hong-jun Li Zheng-liang Bai Qiang
    2010, 38(4):  112-118，124.  doi:10.3969/j.issn.1000-565X.2010.04.021
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    In this paper,the ultimate bearing capacities of steel tube-gusset plate connections with a tube size of 219×6 and with 1/4 annular ribbed plate subjected to negative eccentric force are analyzed.The investigation is performed for the connections with constant diameter-thickness ratio but variable length-diameter ratio and negative eccentricity,and for the connections with constant length-diameter but variable tube diameter,tube thickness and joint plate length.Then,a formula to calculate the ultimate bearing capacity is proposed.The results indicate that the negative eccentricity is unfavorable to the bearing capacity of steel tube with a length-diameter ratio higher than 30 because the entirety stability of steel tube is the main effect factor.However,the negative eccentricity is favorable when the length-diameter ratio is less than 30 because the local bucking is prior in this situation.It is also indicated that the tube diameter,the tube thickness and the joint plate thickness all affect the ultimate bearing capacity significantly,and that the proposed formula is applicable and feasible for design.

    Calculation Method of Horizontal Displacement of Frame-Composite Shear Wall Structure
    Guo Meng Yao Qian-feng
    2010, 38(4):  119-124.  doi:10.3969/j.issn.1000-565X.2010.04.022
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    On the basis of the displacement calculation of the frame-shear wall structure and by considering the shear deformation of the multi-ribbed composite wall,the differential equations of horizontal displacement of the frame-composite shear wall structure respectively under reverse triangle load,uniform load and top concentrated load are established,and the analytical solutions to the equations are obtained.Then,a case analysis is performed with a 12-layer frame-composite shear wall structure.It is found that the shear deformation of the structure is an important component of the total deformation,so that it should be taken into consideration in the displacement calculation of the frame-composite shear wall structure.Moreover,by comparing such mechanical properties as displacement and stiffness between the frame-composite shear wall structure and the common frame-shear wall structure,it is found that（1） shear and bending deformations are two main components of the total displacements of the two structures,and the proportion of shear deformation to the total displacement varies with the structure type;（2） the composite wall is a kind of bearing member with alterable stiffness and damping;and（3） the frame of the frame-composite shear wall structure is dangerous when the floor displacement angle reaches 1/250.

    Human-Induced Vibration Under Walking-Crowd Excitation
    Li hao Jian Fang-liang
    2010, 38(4):  125-130.  doi:10.3969/j.issn.1000-565X.2010.04.023
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    Proposed in this paper is a refined analysis method of human-induced vibration under walking-crowd excitation,which is based on the researches on biomechanics and transportation.In this method,first,the walking speed-frequency relation is derived by fitting the experimental data in biomechanics.Then,the relationship between the speed and the density of crowd flow is investigated according to the corresponding transportation model.Moreover,a refined random crowd load model is established based on the speed-density relationship and the single-human load model in structure field,according to which a dynamic balance equation is deduced and solved using a self-compiled program,with the human-induced vibration response of the structure being obtained.Finally,the comfort of the structure under walking-crowd excitation is evaluated according to the ISO2631 standard,and the results are compared with those obtained by the BS5400 model.It is demonstrated that,as the proposed load model fully considers the crowd load,it avoids the blindness in parameters selection during the human-induced vibration analysis..

    Mechanical Behavior of Superelastic NiTi Wires
    Ling Yu-hong Peng Hui-hong Zhang Shuai
    2010, 38(4):  131-135，155.  doi:10.3969/j.issn.1000-565X.2010.04.024
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    This paper deals with the effects of the cyclic loading number,the strain amplitude and the loading rate on such mechanical behaviors of shape memory alloy wires as the phase transformation stress,the energy consumption per cycle,the deformation modulus,the equivalent damping ratio and the residual strain.Experimental results show that（1） at a certain loading rate,both the forward and the inverse transformation stresses decrease with the increase of the cyclic loading number,especially the former;（2） the forward transformation stresses tend to be stable after 20 cycles,while the inverse ones be stable after only 5 cycles;（3） with the increase of the cyclic loading number,the energy consumption per loading cycle decreases and the amplitude is up to 33% when the cyclic number increases from 1 to 30;（4） the residual strain increases with the increase in the cyclic loading number till to the saturation value of 0.4% after 30 cycles;（5） the equivalent damping ratio increases with the strain amplitude till to the maximum at a strain amplitude of 7%,then it slightly decreases,while the unloading modulus decreases with the increase in the strain amplitude;and（6） the loading rate affects not only the transformation stress but also the energy consumption-specifically,with the increase in loading rate,the transformation stress increases,while the energy consumption slightly decreases.

    Computer Science & Technology
    Depth Recovery from Defocus Based on Relative Blur and Edge Enhancement
    Zhang Quan-bing Zhang Ai-ming
    2010, 38(4):  136-140.  doi:10.3969/j.issn.1000-565X.2010.04.025
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    This paper deals with the depth recovery from defocused images by improving Favaro＇s iteration method based on thermal diffusion equations.In the investigation,two defocused images are respectively divided into two regions according to the relative blur,whose borders are highly consistent with the image edge and can be easily determined by strengthening the image edge during the solving of the thermal diffusion equation via iteration.The depth can be accurately obtained according to the determined U＋ and U-boundaries.The effectiveness of the proposed method is then validated by simulation and real image experiment.Simulated results show that the proposed method is of high robustness,and the real-image experimental results show that the method is superior to Favaro＇s method in terms of depth recovery.

    Discrete Particle Swarm Optimization Model for Set-Based Combinatorial Optimization Problems
    Chen Zi-yu He Zhong-shi He Jing-yuan
    2010, 38(4):  141-146.  doi:10.3969/j.issn.1000-565X.2010.04.026
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    Proposed in this paper is a discrete particle swarm optimization model to solve set-based combinatorial optimization problems.The model introduces set concepts and operations in the particle swarm optimization,defines a search space of variable set and redefines the velocity and location of particles as well as the operators working in the defined search space.Thus,it possesses the characteristics of both particle swarm optimization and set-based combinatorial optimization.Finally,the proposed model is applied to the knapsack problem,a typical set-based combinatorial optimization problem,and it is compared with the binary particle swarm optimization（BPSO）.The results indicate that the proposed model is of stronger searching ability and higher stability.

    Effects of Several Evaluation Metrics on Imbalanced Data Learning
    Lin Zhi-yong Hao Zhi-feng Yang Xiao-wei
    2010, 38(4):  147-155.  doi:10.3969/j.issn.1000-565X.2010.04.027
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    As most traditional classifiers optimized with the accuracy metric are unsuitable for imbalanced data learning（IDL）,this paper performs a meta-learning on a support vector machine（SVM） model,and investigates the IDL affected by such metrics as the accuracy,the balance accuracy,the geometric mean,the F1 score,the information gain,the AUC（Area Under ROC Curve）,as well as the two new metrics proposed in this paper,namely GAF and GBF.Moreover,simulation experiments are conducted on 16 imbalanced datasets from UCI,with a statistical analysis of the experimental results being also carried out.It is indicated that（1） there are distinct differences in the effects of these metrics on the classifier＇s performances;（2） even for the support vector machine（SVM）,an advanced learning method,its output classifier is still readily biased to majority class when the classifier is selected by maximizing the accuracy;（3） through the optimization with the help of other metrics,it is feasible to output bias-rectified SVM classifiers,which are of better overall performance,especially in terms of the prediction ability for minor classes;and（4） the output SVM classifiers optimized with GAF and GBF metrics are of stable and good performance.

    Image Retrieval Based on Visual Semantics and RSSVM
    Li Da-xiang Peng Jin-ye He Jin-fang
    2010, 38(4):  156-161，166.  doi:10.3969/j.issn.1000-565X.2010.04.028
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    Based on the visual semantics of images,a novel space-transforming model is designed,and a new semantics description method is proposed.In the investigation,first,the method of Normalized Cut（NCut） is used to segment each image into several regions,and such visual features as color,texture and shape,etc.of each region are extracted.Next,all the visual features in the training set are clustered by using the K-Means method,and each cluster center is regarded as a ＂visual semantic＂ to construct a projection space.Then,a nonlinear function is defined to map each image into a point in the projection space.Thus,all the projection features of the image are obtained.Moreover,in order to improve the training efficiency and performance of classifiers,projection features are reduced in attributes via the rough set（RS） method,and are trained and classified by the support vector machine.The results are finally compared with those based on the Corel image set.It is found that the proposed method is robust to cluster number,and is superior to the other methods in terms of retrieval performance.

    Estimation of Flow Size Distribution During Random Packet Sampling
    Zhang Hai Xu Yong Zhang Ling
    2010, 38(4):  162-166.  doi:10.3969/j.issn.1000-565X.2010.04.029
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    In order to improve the estimation accuracy of flow size distribution,several maximum likelihood estimate（MLE） algorithms using SYN flag information and TCP sequence numbers are compared.The results show that the algorithms using SYN flag and SEQ information in TCP flow,especially the algorithm using both SYN flag and SEQ sequence numbers,are more accurate than the simple sampling estimation.Then,a nonuniform grained estimation algorithm of flow size is proposed,which implements the estimation with fine-grained estimators for the flow with small size and coarse-grained ones for the flow with large size.Case study demonstrates that the proposed algorithm is applicable and greatly improves the estimation accuracy of large-size flow with less computation.

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