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Table of Content

    25 November 2011, Volume 39 Issue 11
    Chemistry,Chemical & Energy Engineering
    2011, 39(11):  1-5. 
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    Alkaline sulfite was used to pretreat eucalyptus lignocellulose,and the product was investigated by means of FT-IR,SEM and XRD. The results show that,after the pretreatment,some lignin and hemicellulose hydrolyze,the relative crystallinity of cellulose decreases by 14. 34%,the carbohydrate in eucalyptus becomes incompact,the pit membrane breaks and more fiber fragments form,thus greatly improving the accessibility of the cellulase in the later treatment. Moreover,it is found from the further enzymatic hydrolysis that,after the pretreatment,the mass of xylose and glucose amounts respectively to 67. 33% and 88. 11% of that of the raw eucalyptus,that the corresponding yields are respectively 7. 51 and 4. 33 times higher than those without pretreatment,and that 52. 39% of lignin in the raw eucalyptus can be reused from the enzyme solution scraps.

    Zou Hua-sheng Li Jian Chen Wen-biao
    2011, 39(11):  6-11. 
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    A kind of solid base catalyst was prepared by means of the isovolumetric impregnation,and the product was used to catalyze the transesterification of Jatropha curcas oil to prepare biodiesel. The influences of carrier,active component and carrier dryness on the properties of the solid base catalyst were analyzed,and the optimal conditions for preparing the catalyst were obtained. Moreover,the effects of ultrasonic radiation,methanol-to-oil molar
    ratio,catalyst dosage and reaction time on the conversion of methyl ester were discussed,and the kinetics of transesterification under mechanical agitation and ultrasonic irradiation were explored,with the corresponding kinetic equations being obtained. The results show that the catalyst is of the highest performance when it is prepared at 300℃ by a 3-h drying,with NaX and KOH ( with a loading amount of 15%) respectively as the carrier and the active component,that the conversion of methyl ester reaches 95. 8% when the transesterification is enhanced with 40Hz and 90W ultrasonic at 32℃ for 60min and when the methanol-to-oil molar ratio and the catalyst dosage are respectively 8:1 and 2%,that the reaction rate constant under ultrasonic irradiation is 3. 79 times than under mechanical agitation,and that the reaction orders under ultrasonic irradiation and mechanical agitation are 0. 4889 and 0. 6431,respectively.

    Chen Gang Wu Yan-liang
    2011, 39(11):  12-16,21. 
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    The swelling and dissolving of cotton fibers in zinc chloride solution during the production of vulcanized paper were investigated and their influences on the structure of the prepared vulcanized paper were analyzed. The results show that cotton fibers swell as soon as they contact with zinc chloride solution,with the swelling ratio varying from 1. 2 to 1. 3,that the swelling ratio is higher when there exists severe internal fibrillation,and that,after
    the treatment with zinc chloride solution,the crystallization index of cotton fibers decreases from 80. 1% to 76. 5%,the intermolecular hydrogen bonds weaken,and the crystal form keeps unchanged. Moreover,it is found that the intense swelling and dissolving of fibers result in compact contact and more bonds,thus greatly decreasing the porosity and enhancing the compactness and uniformity of the vulcanized paper.

    Fu Shi-yu Xie Chuan-long Zhang Liang-liang Zhan Huai-yu
    2011, 39(11):  17-21. 
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    In order to overcome the disadvantages of the existing content determination methods of ethoxyl in ethyl cellulose,a new method based on the headspace gas chromatography ( HS-GC) is proposed. In this method,first,ethyl cellulose is conversed into ethyl iodide by reacting with hydriodic acid. Next,sodium hydroxide is added in headspace sample vials to neutralize excessive hydroiodic acid before the HS-GC performance,thus avoiding the damage to the sample injection system and the column. Then,toluene is used as the internal standard to perform a HS-GC process. Finally,the content of ethoxyl in ethyl cellulose is determined according to the ethyl iodide content obtained by the internal standard method. The authors investigate the effects of hydrolysis temperature,hydrolysis time,equilibration temperature,equilibration time and matrix additive on the determination and find that,when the hydrolysis temperature ranges from 140 to 150℃,the determination results vary slightly and the reaction ends within 1. 0 h,that a vapor-liquid equilibrium is reached at 80℃ after a vial equilibration for 30min,that the addition of cellulose helps to eliminate the matrix effect and to obtain good linearity between ethyl iodide content and peak area. The authors also indicate that the proposed method is of good repeatability and average recovery because the RSD ( Relative Standard Deviation) of determination results is very low ( 2. 83%) and the recovery rate is very high ( 99. 6%) ,and that results obtained by the proposed method accord well with those obtained by chemical titration.

    Ouyang Xin-ping Zhan Lei Chen Kai Yang Dong-jie Qiu Xue-qing
    2011, 39(11):  22-26,39. 
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    This paper deals with the properties of lignin-modified phenol-formaldehyde resin ( LPF) adhesive synthesized with lignin partially substituting for phenol under various conditions. Then,the influences of such factors as the substitution rate of lignin for phenol,the sodium hydroxide dosage,the formaldehyde-to-lignin mass ratio and the solid content of the product on the properties of LPF were discussed,and the factors were optimized. Finally,the thermal properties of LPF were analyzed by means of DSC. The results show that the alkali activation and hydroxymethylation help to improve the chemical reactivity of the lignin,that the adhesive prepared under the optimal conditions ( a substitution rate of 50%,a sodium hydroxide dosage of 4. 5%,a formaldehyde-to-lignin mass ratio of 8: 100 and a solid content of 41. 4%) is of high bond strength ( up to 2. 04MPa) as well as low residual formaldehyde and phenol contents ( much less than those regulated by the national standard) ,and that the prepared LPF adhesive is superior to the phenol-formaldehyde resin adhesive because it is of low curing temperature and high curing rate.

    Liu Quan-bing Luo Chuan-xi Song Hui-yu Liao Shi-jun
    2011, 39(11):  27-32. 
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    Cathode material LiFePO4 /C was successfully prepared via the spray drying-carbothermal reduction method,with inexpensive ferric iron ( Fe3+ ) as the iron source and with polyethylene glycol ( PEG) as the assisted template and the carbon source. Then,the microstructure of the material was characterized,and the effects of PEG dosage and calcination temperature on the structure and performance of the material were investigated. The results show that the product possesses mesoporous structure,beautiful hierarchical spherical morphology,high specific surface area,high capacity and excellent cyclic stability,that too low PEG dosage may result in incomplete reduction of Fe3+,while excessive PEG may hinder the Li + diffusion because the carbon layer is too thick,that the optimum PEG dosage is about 150 g /mol,that appropriate calcination temperature may result in high conductivity because it decreased the disordered /graphene ( D/G) proportion of the residual carbon,that the optimum calcination temperature is about 750℃,and that the material prepared under the optimal conditions,whose initial discharge capacities at the rates of 0. 1,0. 5,1. 0,2. 0 and 5. 0C are respectively 149. 2,139. 0,116. 8,102. 4 and 82. 1mAh/g,is of good rate-cyclic stability.

    Hong Yu-xiang Deng Xian-he
    2011, 39(11):  33-39. 
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    In this paper,first,the heat transfer and flow resistance characteristics of 98% sulfuric acid in the converging-diverging tubes inserted with twisted tapes are numerically simulated,and the corresponding heat transfer effect are compared with that in the smooth tube and in the single converging-diverging tube. Then,the effects of flow state and thermal physical property on the comprehensive heat transfer performance of the converging-diverging tubes inserted with twisted tapes are analyzed,and the field synergy between velocity and heat flow fields is discussed. The results indicate that the comprehensive performance of the converging-diverging tubes inserted with twisted tapes are higher than that of the single converging-diverging tube under laminar flow,while are lower under turbulent flow,that small twist ratio of twisted tapes is beneficial to the improvement of the comprehensive performance under laminar flow,while large twist ratio is beneficial under turbulent flow,and that the synergetic enhancement
    of the heat transfer by the twisted tapes is more significant under laminar flow than that in turbulent flow. In addition,in heat exchangers of converging-diverging tubes inserted with twisted tapes,the fluids with low and very high viscosity are of better heat transfer performance than that with medium viscosity.

    Tang Xin-yi Zhu Dong-sheng Chen Hong
    2011, 39(11):  40-46. 
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    In order to investigate the effects of turbulators on the heat transfer in ribbed channels,the heat transfer and flow characteristics of elliptical ribbed channels with and without deflector are numerically simulated by using a realizable k-ε turbulence model,and the results are compared with those of the traditional grooved channel. The results show that the heat transfer coefficient of elliptical ribbed channel is about 3 -4 times that of the traditional
    grooved channel,that the heat transfer coefficient and the pressure drop both increase with the rib height,that the adoption of deflector remarkably raises the heat transfer coefficient,that the heat transfer coefficient of the ribbed channel with deflector mounted at the top of rib downstream is 33% higher than that of the channel without curved vanes,and that,with the movement of the deflector along the arc length of ribs,the heat transfer coefficient first increases and then decreases,while the pressure drop continuously decreases. Moreover,it is found from comprehensive comparison that the ribbed channel is of the highest comprehensive performance when the deflector are mounted at the location of 0.9 time arc length of the rib downstream,that the heat transfer coefficient reaches the maximum when the vanes are mounted at the location of 0.7 time arc length of the rib downstream,and that the nearness of the deflector for the flow separation point is favorable for the heat transfer enhancement.

    Zhou Ze-guang Zhu Dong-sheng Wu Hong-xia Zhang Hong-sheng
    2011, 39(11):  47-52. 
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    The heat transfer characteristics of the thermoelectric generator using air natural convection,air forced convection and water cooling on the cold side were analyzed based on the thermal network analysis,and the corresponding experimental investigation was carried out. The results show that,as compared with the air natural convection,the air-forced convection and the water cooling modes enhance the heat transfer between the heat sink fins
    and the ambient and reduce the temperature and thermal resistance on the cold side,and that the main thermal resistance changes from the convectional one between the heat sink fins and the ambient to the contact one between the generator as well as the heat source and the sink on the cold side. When the heat flux of the heat source keeps constant,strengthening the heat transfer on the cold side of the generator may decrease the temperatures of the heat source and the hot side,while the temperature difference between the hot and the cold sides of the generator has no significant improvement. When the heat flux of the heat source is low,strengthening the heat transfer on the cold side of the generator can not dramatically increase the output power of the generator. When the heat flux of heat source is high,strengthening the heat transfer on the cold side may greatly increase the output power of the generator. Moreover,at a heat flux of 50 W,the output power in air-forced convection cooling and water cooling respectively increase by 27. 9% and 39. 5%,as compared with that in air natural convection cooling.

    Mechanical Engineering
    Pu Han-jun Xie Xiao-peng Jia Shang-yu Liang Guang-chi Yun Xiang-yong Pan Hai-ning
    2011, 39(11):  53-58. 
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    Based on the differential geometry and the elastomechanics theory,the physical model and of a non-rotating wire rope under straight tension is established,and the corresponding mechanical equations are deduced. Then,based on the space spiral equations,an entity model of the rope is set up using the three-dimension CAD software ProE and is introduced in ANSYS to carry out mechanical analyses for the verification of the proposed model.  It is found that the calculated results obtained by the proposed model are basically consistent with those of the finite element analysis,which means that the proposed model is correct.

    Sun Wei Zhang Xian-min Wang Nian-feng Guan Yi-sheng
    2011, 39(11):  59-64,81. 
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    Three large-deflection flexible Hooke hinges using reeds as the basic units are constructed,and their own structural characteristics are analyzed in detail. Then,the deformations of the flexible Hooke hinges under pure torque loads are analyzed by using a pseudo-rigid model. Moreover,under the given parameter conditions,theoretical calculations are performed for the Hooke hinges,and the results are compared with those of the finite element
    analysis. It is indicated that these three flexible Hooke hinges are all of the basic rotation characteristics of original Hooke hinges and can provide large two-dimension rotating deflection,that the theoretical results obtained by the pseudo-rigid model accord with those of the nonlinear finite element analysis,and that,under the given structural parameters,Hooke hinge C is a new type of large-deformation flexible hinge because it is of large output angle up to ± 11.9 °,small rotational center drift and small input coupling,so that it can be applied to the flexible parallel mechanism and flexible precision positioning platform.

    Zhang Guang-yu Qi Li-qun Dong Hui-juan Shan Xiao-biao
    2011, 39(11):  65-70. 
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    In order to investigate the contact mechanics and the friction as well as wear mechanism of small-module gears in a spacecraft in vacuum environment,a mathematical model to describ the contact stress loading on the gear meshing interface was established,and the stress distribution was analyzed. Then,a vacuum friction-and-wear experimental platform of the gear system was set up,and the main friction and wear behaviours of a gear in vacuum and atmorsphere are comparatively investigated. Finally,according to the micromorphology of wear scar at defferent locations on the meshing surface,the relationship between the contact stress distribution in the gearing interface and the friction and wear behaviours of the gear is analyzed. The results show that the occurrence of adhesive wear in vacuum environment is more easier than that in atmospheric condition,that the contact stress distribution closely relates to the adhesive wear,that the contact stress value has a decisive effect on the adhesion of gear,and that the
    wear form of the space gear in vacuum environment is mainly adhesive wear,while that in atmorspheric conditon is fatigue wear combining with abrasive wear.

    Li Chao-yang Chen Bing-kui Liu Jing-ya
    2011, 39(11):  71-75. 
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    Proposed in this paper is a new type of cycloid double-enveloping meshing pair that consists of cycloid gear and enveloped internal gear. In the investigation,first,the tooth profile equations of the cycloid gear and the internal gear were proposed,and the integrative curvature radii of two types of contact points in the meshing pair were compared with each other. Then,a prototype of a new gear transmission that takes the proposed meshing pair as the main transmission part was trial-produced to meet the requirements of the driving system of a satellite-pointing mechanism,and the corresponding technical specifications,such as the transmission accuracy,the torsional stiffness and the output torque,were tested. The results show that the new type of gear transmission is of high transmission accuracy,low backlash and high torsional stiffness,etc.

    Qin Meng-yang Ye Bang-yan Liu Lei-feng He Ai-dong
    2011, 39(11):  76-81. 
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    In order to solve the problem existing in the turning of workpiece simultaneously being loaded with high prestress,a prestress-loading device was designed for the prestressed turning. Then,some turning experiments for a screw were carried out with PCBN tools under different prestresses to investigate the loaded prestress,the surface residual stress,the surface roughness,the impact of prestress to cutting force and the wear of PCBN tools. Moreover,the results were compared with those of the original hard cutting. It is found that the designed loading device can effectively load prestress on workpiece,that the prestressed hard cutting generates high residual compressive stress on the screw surface and results in fine machining surface,and that the prestress has no significant effect on the cutting force and tool wear.

    Yi Jing-rong Lai Chao-an
    2011, 39(11):  82-87. 
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    By analyzing the construction and operation mechanism of manufacturing systems,a evaluation model of coordination degree including the objective coordination,the structure coordination and the operation coordination is established,and a quantifycation method integrating several macro parameters is proposed by quantifying the abovementioned factors. Then,a case study is conducted using the production and management data of a electronic manufacturing enterprise. The results indicate that coordination degree is feasible and applicable in evaluating the comprehensive performances of manufacting systems.

    Wen Yuan-mei Huang Shi-sheng Liu Gui-xiong
    2011, 39(11):  88-91,103. 
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    By using a self-developed high-speed camera and electrical signal measuring system,the droplet transfer processes of high-speed pulse twin-wire co-pool gas-shielded metal arc welding ( TCGMAW) under different pulse current frequencies were observed,and the effects of pulse current frequency on the droplet transfer and the welding seam appearance were ana-lyzed. Experimental results show that,under the welding specification adopted in this paper,high pulse current frequency ( 140Hz) may result in projected droplet transfer for the front wire and spray transfer for the rear one,while the low frequency less than 50Hz may result in projected droplet transfer for both the front and the rear wires,that the frequency varying form 50 to 140Hz may result in spray droplet transfer for both the front and the rear wires,and that good welding seam appears at the frequencies from 50 to 100Hz.

    Zhu Jun Tian Zong-jun Liu Zhi-dong Shen Li-da Huang Yin-hui Wang Gui-feng
    2011, 39(11):  92-97. 
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    In order to overcome the disadvantages of the traditional jet electrodeposition,a novel friction-aided technology was proposed. To make a comparison,nickel deposition layers were prepared by using the proposed and the traditional technologies,respectively. Afterwards,the microstructure,surface morphology,microhardness and magnetic properties of the layers were investigated by means of XRD,TEM,microhardness test and vibrating-sample magnetic strength test. The results show that the friction-aided technology helps to prepare electrodeposition layer with smooth and bright surface and well-organized structure,that the deposited nickel layers are all in nano-crystalline microstructure whose average size ( about 10 nm) is far less than that prepared by the traditional jet electrodeposition technology,and that the friction helps to refine the grains,improve the microstructure,increase the hardness of the deposited layer,and greatly change the magnetic properties of the deposited layers.

    Zhang Tie Dai Xiao-liang
    2011, 39(11):  98-103. 
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    In this paper,first,an error model of a robot is established via coordinates' homogeneous transformation and on the basis of the DH kinematic model. Next,in order to avoid the great change of the link distance due to small deviation of axes,another error model of parallel joints is set up via the homogeneous transformation and on the basis of the modified DH kinematic model. Then,the distance error of every two points in space is used to evaluate the absolute positioning accuracy of robot. Moreover,by the two above-mentioned models,a kinematic calibration model based on distance error,which avoids the complex coordinate transformation and simplifies the mea-surement process,is presented. Finally,the position of an end point of the self-developed 6-DOF industrial robot is measured by a three-coordinate measuring machine. The results indicate that,after the solving, compensation and correction of joint parameters,the average absolute distance error of the end point reduces by more than 50% and the positioning accuracy of the robot obviously improves.

    Materials Science & Technology
    Su Da-gen Fu Wen-xiang Zhong Ming-feng
    2011, 39(11):  104-108. 
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    A kind of solar reflection material,NaZnPO4,was prepared by heat-treating the precursor obtained via the direct precipitation,with Zn( NO3)2·6H2O,H3PO4 and anhydrous sodium carbonate as raw materials. The product was then characterized by means of UV-Vis,XRD and TG/DSC. The results show that the phosphorus-tozinc molar ratio of the raw materials plays an important role in the structure of NaZnPO4,that the appropriate phosphorus-to-zinc molar ratio ranges from 1. 7 to 2. 0,that the heat treatment temperature for preparing NaZnPO4,which is important to the solar reflection,should be controlled in the range from 400 to 800℃,and that the product with the heat treatment at 600℃ is of the best solar reflection property,with its average reflection rate being up to 95. 2%.

    Wang Min Guo Hui-yong Huang Wen-bo Li Wen-fang Zhang Guo-ge
    2011, 39(11):  109-113,119. 
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    Barium titanate film with good surface morphology and small surface roughness was prepared via microarc oxidation,and the corresponding preparation parameters were optimized by orthogonal test. Then,the film prepared under the optimal conditions was characterized,and the influences of solution concentration,current frequency,current density and reaction time on the surface morphology and roughness of the film were investigated. The results show that,under the optimal conditions,namely a Ba( OH)2 solution concentration of 0. 5mol /L,a current frequency of 100Hz,a current density of 2. 0 A/cm2 and a reaction duration of 5 min,the prepared film is mainly composed of tetragonal BaTiO3 and is of high dielectric constant ( 113. 0) at 1kHz,that the surface roughness of the film decreases with the increase of solution concentration and current frequency ( less than 150Hz) and with the decrease of current density and reaction time.

    2011, 39(11):  114-119. 
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    In this paper,three kinds of organic lightweight aggregate concrete,whose coarse aggregate was partially substituted respectively by virgin expanded polystyrene ( EPS) beads,recycled EPS beads and waste rubber particles,respectively,were prepared,and the failure mode,elastic modulus and complete stress-strain curve of the concrete under uniaxial loading were investigated. Moreover,the complete stress-strain curves of the organic lightweight aggregate concrete were fitted by using different formulas. The results illustrate that the complete stress-strain curves of the organic lightweight aggregate concrete are all similar to those of the ordinary concrete,while the feature points on the curves are significantly different from those of the ordinary concrete,that the elastic modulus and peak stress of the concrete are remarkably lower than those of the control concrete,that the elastic modulus of the recycled EPS concrete is similar to that of the virgin EPS concrete,that rubber concrete is of the lowest elastic modulus and peak stress but it is of the highest ratio of peak elastic modulus to peak stress,that the elastic modulus,peak strain and peak stress of EPS concrete all decrease with the increase in EPS dosage,and the complete stressstrain curves of the three kinds of concrete fitted with different formulas all accord well with those obtained by experiments,with the correlation coefficient being more than 93%.

    Lu Yu-dong Wan Ming En Yun-fei Wang Xin Cheng Jun He Xiao-qi
    2011, 39(11):  120-124. 
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    The failure position and failure mode of SnAgCu flip-chip solder bumps enduring thermal stress and electrical/thermal complex stress before shear test were investigated,and the difference in microstructure of the interconnecting structure enduring different stresses were compared. Moreover,the effects of electromigration induced by high current density on the shear strength and the fracture mode of Al /SnAgCu /Cu interconnecting structure were analyzed. The results indicate that there are two shear fracture modes of the flip-chip solar bumps after the aging at a high temperature,namely the brittle fracture on the Al-solder interface and the ductile fracture in the solder bumps,that the failure position and the fracture surface morphology of the interconnecting structure change after the aging at a high temperature and high current stress,that the pancake-type voids and the abnormal growth of intermetallic compound induced by electromigration are the main cause of failure,and that the two fracture modes alternately distribute in the interconnecting structure due to the alternate change of current flow in flip-chip solder bumps.

    Luo Zong-qiang Xin Bao-liang Zhang Wei-wen Li Yuan-yuan
    2011, 39(11):  125-131. 
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    The influence of pH value on the corrosion resistance and the corrosion behavior of wear-resistant casting alloy Cu-17Ni-3Al-X in 3. 5% ( mass fraction) NaCl solution was investigated via static immersion test,electrochemical test,SEM,XRD and XPS. The results show that,in 3% NaCl solution,the corrosion rate of the alloy decreases with the increase of pH value,that the alloy is of excellent corrosion resistance in neutral and alkaline
    NaCl solution,that no compact protection film forms on the alloy surface when the pH value is 3,that Ni-rich and Al-rich Cu2( OH)3Cl and Cu2O films form on the alloy surface when the pH value is 6,8 and 10,and that compact Cu2O film is easy to form when the pH value is 12. In conclusion,the difference in corrosion rate of the alloy in NaCl solution with different pH values is due to the difference in cathodic reaction and the protection films,and the alloy suffers from intergranular corrosion around the second phases in acid solution.

    2011, 39(11):  132-137,154. 
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    The dissolution behavior of solid iron in liquid zinc at a high temperature under natural convection condition was investigated,and the corresponding dissolution mechanism was discussed. The results show that,when solid iron is immersed into liquid zinc,the saturated concentration of Fe in liquid zinc gradually increases with the temperature,that the dissolution rate greatly increases with the temperature of liquid zinc,that the dissolution rate
    constants of liquid zinc at 520,560 and 600℃ are respectively 2. 1 × 10 -6,5. 06 × 10-6and 7. 15 × 10-6 m/s,that the dissolution of solid iron in liquid zinc at 520℃ is mainly controlled by the chemical reaction between solid iron and liquid zinc and the diffusion of iron atoms in Fe-Zn alloy layer,while that at 560 and 600℃ is controlled by the diffusion of iron atoms across the concentration boundary layer in liquid zinc.

    Automotive Engineering
    Ye Zi-bo Fu Xing-feng Zhou Si-jia
    2011, 39(11):  138-143. 
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    According to the structural characteristics of a domestic hybrid electric vehicle ( HEV) ,a simulation model to describe the rear-end collision is established based on the finite element analysis to analyze and optimize the safety of the vehicle. Then,the bending mode,the torsional mode and the torsional stiffness of the HEV are calculated and compared with those of the prototype vehicle. Moreover,by controlling the displacements in both the X direction of power battery box and the Z direction of hook at the upper backrest of back row seat,the existing structure and safety of the whole-vehicle rear-end collision are optimized and redesigned. The results show that the HEV comes up to the standard of conventional vehicles in terms of bending mode,torsional mode and torsional stiffness,etc. The rear-end collision test of a real vehicle proves that the improved security structure meets the design requirements well.

    Li Shi-wu Tian Jing-jing Sun Wen-cai Wang Jian-wu Wang Hai-zheng
    2011, 39(11):  144-148. 
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    In order to avoid the resonance of drum under external excitation during tire tests,first,the topological optimization analysis of 工-shaped drum was carried out,with the element density as the design variable,the volume reduction of 50% as the constraint and with the first-order natural frequency as the objective function. Next,the pseudo-density distribution of the drum was obtained,and the 工-shaped structure of drum was modified according
    to the analysis results. Then,the structure size of the modified drum was optimized via 50 iterative calculations. Finally,on the premise that the first-order natural frequency was more than 60 Hz,the structure size of drum was taken as the optimum when the ratio of the first-order natural frequency to the total mass reached the maximum 0. 053 9. Optimization results show the total mass of the modified drum decreases by 69. 95kg and first-order natural frequency reaches 64. 384Hz,which is 21. 972Hz higher than that of the original drum.

    2011, 39(11):  149-154. 
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    In order to overcome the disadvantages of the existing performance analysis methods of torque converters,the response surface method is adopted to optimize the blade parameters of hydraulic torque converter based on the three-dimension flow simulation. In the investigation,first,the efficiency and torque ratio of the torque converter are calculated according to the simulated results and considering mechanical loss. Then,an optimal model of the blade is established based on the results of orthogonal test,with the highest efficiency as the target function,the starting torque ratio as the constraint and with a second-order polynomial as the response surface function. Finally,a optimization calculation is performed based on the proposed model. The results indicate that,after the optimization,the top efficiency increases by 3 points of percentage and the starting torque ratio increases by 4. 5%,which means that the proposed method is feasible.

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