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    25 July 2006, Volume 34 Issue 7
    Wang Zhen-min Huang Shi-sheng Xue Jia-xiang
    2006, 34(7):  31-34,59. 
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    In order to meet the requirements of the double-wire pulse metal active gas(MAG)welding,a novel soft-switching high-speed double-wire pulse MAG welding inverter,which combines the soft-switching technology,the double closed loop control technology and the can bus technology,was developed. The proposed inverter was then tested on a computer information platform. The results indicate that the novel welding inverter meets the re-quirements of high-speed double-wire pulse MAG welding well because it possesses excellent dynamic and static characteristics and reliable performance in the synchronic control between the master inverter and the slave inverter.

    Materials Science & Technology
    Zhuang Zhi-qiang Su Tao-long Liu Bo Pan Yao-dong Liu Yong Wang Xin
    2006, 34(7):  1-6. 
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    For the homogeneous mixing of BaTiO3(BT) powders with dopants and the exact control of the micro-structures,phases and electrical properties of materials,a heterogeneous nucleation method was used to coat dopant Y(OH)3 on the surface of nano—crystallized hydrothermal BT powders. The coating effect of Y(OH)3 on the pow-ders prepared by two methods was revealed according to the capillary wettability improvement of the coated powders in water and to the effect of the rotating speed on the eccentricity in separating the BT powders from the slurry using a centrifuge. And the influence of doping method on the semiconductivity and room—temperature resistance of the Y-doped BT ceramics was investigated. The properties of the BT-based PTCR ceramics and the dielectric ceramics with fine grain prepared by heterogeneous nucleation method were discussed also. It is demonstrated from the expe-rimental results of capillary wettability that Y(OH)3 can be nicely coated on BT powders via the surface coating.

    Zhao Yao-ming Zhou Ling Wang Zhao-yang
    2006, 34(7):  7-11. 
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    A kind of biodegradable material poly(ε-caprolactone-co-lactic acid)[P(CL-co-LA)]was synthesized via the direct melting c0p0lymerizati0n of lactic acid(LA)and ε-caprolactone(CL). The influences of the prepo-lymerization time,the c0p0lymerizati0n time and the catalyst type on the intrinsic viscosity of P(CL-co-LA)werealso investigated. The results indicate that P(CL-co-dl-LA)with an intrinsic viscosity of 0.4733dL/g can be pre-pared by the direct melting copolymerization of dl-LA and CL in a mole ratio of 3:7 at 180℃and 70 Pa for 12 h,with 0.5%(mass fraction)of SnCl2 as the catalyst,and that P(CL-co-l-LA)with an intrinsic viscosity of 0.4121dL/g can be produced by the direct melting copolymerization of l-LA and CL in the same conditions for 16 h. As compared with the lactide ring—opening polymerization(ROP),the direct melting c0p0lymerization 0f LA and CL is proved more practicable and simpler.

    Ye Wei-hua Wang Chao-yang Zheng Ying Liu Xin-xing Tong Zhen
    2006, 34(7):  12-16. 
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    Ibuprofen-poly(3-hydroxybutyrate-co-3-hydroxyvalerate)nanoparticles with the diameter of 500 to 800 nm were fabricated by means of the solvent evaporation method. The effects of the type and concentration of the emulsifier,the pH value of the water phase,the mass ratio of drug to polymer and the hydroxyvalerate(HV)con-tent of the polymer on the encapsulation efficiency and drug loading of the nanoparticles were also investigated. The optimized conditions were then chosen as:the pH value of water phase 4.0,the mass ratio of drug to polymer 10:50,the HV mass fraction 6% to 10%,and the polyvinyl alcohol concentration 1%(volume fraction). Moreo-ver,chitosan and sodium alginate were absorbed on the IBU-PHBV nanoparticles via the layer-by-layer(LbL)selfa-ssembly technique,resulting in a decrease in the burst amount of nanoparticles from 70% to 15% respectively be-fore and after coating polyelectrolyte in 6 layers,thus coming to the conclusion that the combination of the solvent evaporation and the LbL self-assembly is an effective way to overcome the initial burst release of drugs.

    Liu Ying Li Yuan-yuan Chen Wei-ping Zhang Da-tong Li Wei
    2006, 34(7):  17-20,25. 
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    In order to investigate the superplasticity and the microstructure evolution during the superplastic deforma-tion of ZE10 magnesium alloy sheet,the high-temperature tensile experiments of the sheet were carried out at thetemperatures of 200 to 400℃and at strain rates of 5.5×10-4 to 2.2×10-2s-1,with the microstructure of thesheet being also analyzed. The results indicate that ZE10 magnesium alloy sheet possesses good superplasticity at 350℃and 400℃,the corresponding elongations at the strain rate of 5.5×10-4s-1respectively reaching 227% and 270%,that the original average grain size—25 to 30μm—of ZE10 magnesium alloy sheet scarcely changes during the superplastic deformation,that the microstructure maintains equiaxed-grain dynamically,and that there exist typical cavities on the fracture surface when the sheet is fractured.

    Computer Science & Technology
    Hong Xiao-bin Liu Gui-xiong Lü Yi-hang Wu Zhuo-kui
    2006, 34(7):  55-59. 
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    This paper introduces the intelligent measurement and control system based on the Ethernet,in whichthe XML(Extensible Markup Language)technology is adopted to meet the requirement of openness of the system. By analyzing the XML models and XML document expressing methods of data interface in the system,this paper al-so presents a way to realize the universal data. exchanging interface based on XML. Moreover,the Ethernet intelli-gent measurement and control system with the data-exchanging interface based on XML is applied to a modem greenhouse. The results show that the designed data-exchanging interface based on XML enhances the reliability
    and flexibility of data communication and meets the requirements of openness and crossing platform in the system.

    Wang Ruo-en Chen Jin-chang
    2006, 34(7):  60-64. 
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    An integral slice algorithm is provided based on the integral model to solve the optimal loading problem. The corresponding optimal loading simulation system in three-dimension space is then developed based on the pro-posed algorithm. The system with intuitionistic simulation view and simple data processing is proved feasible by app-lication examples and data analyses,and is also proved effective and intelligent because it can perform harmony loading according to the practical conditions in a virtual loading process. The proposed system can be applied to the effective packing of wares,the optimal loading of conveyances and the high-efficiency storage of warehouses in lo-gistics engineering.

    Shao Ze-ming Zhu Jian-ying Wang Hua-ming
    2006, 34(7):  65-68. 
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    The reason for the low speed of SUSAN algorithm in comer detection is analyzed,and a hierarchical fastcomer detection algorithm based on SUSAN algorithm is proposed. According to the gray similarity around pixels and the comer properties in an image,the theory of lifting wavelet transform and the coarse-to-fine hierarchical strategy are adopted to process the image,with the aim of finding the coarse positions of comers. Then,the comers are finely searched and precisely located by using SUSAN algorithm. Experimental results show that the proposed algorithm mRS fast and saves much runtime.

    Mechanical Engineering
    Liu Gui-xiong Li Xia-ni
    2006, 34(7):  21-25. 
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    The structure and working principle of an integrated optical-fiber proximity sensor that detects both the distance and the orientation and possesses the function of self-compensation are introduced in this paper. The corre-sponding decoupling approach to the sensor is then presented based on the muhiscale characteristics. The decou-pling process can be divided into two parts:classifying the information based on the muhiscale degree and solving the coupling equation via the computational approximation methods with different precisions. The principle,physi-cal meaning and implementation process of the approach are finally discussed,indicating that the proposed ap-proach is so real-time and precise that it can be applied to other similar circumstances.

    Zhang Tie Xie Cun-xi Gong Shu-qiang
    2006, 34(7):  26-30. 
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    A novel patrol and security robot driven by two DC deceleration servo motors is developed in order to meet the requirements of safety in public locations. A classified system is adopted in the control of the robot,which includes the main control level,the coordinating level,the executing level and the remote control level. This paper mainly deals with the DSP control system,the inspection methods of the parameters in the coordinating level and the executing level,and the driver circuit of the motors. Moreover,the algorithms and program of the three-loop control of the robot are proposed. A running experiment is finally carried out,verifying that the proposed control system can completely meet the servo control requirement of the patrol and security robot.

    Qiu Hong-yang Huang Ya-juan
    2006, 34(7):  35-39. 
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    The formation process of automobile engine hood panels is investigated by means of the numerical simu-lation using a dynamic explicit FEA(Finite Element Analysis)software eta/DYNAFORM. Night simulated stam-ping models in two groups are then established to analyze the influences of the initial blank shape and the technologi-cal supplementing dimension on the formation of the engine hood panel, each using the rectangular blank model and the cutting-angle blank model. Proper blank dimension is thus obtained. The results show that the formation is greatly affected by the shape and dimension of the blank,that adjusting the dimension in a certain range can im-prove the stamping formation if the blank shape is unmeet,but can not solve the problem thoroughly,and that the cutting-angle blank,especially the one with an angle of 75°,is more suitable for the formation than the square blank because the latter may cause large size consumption.

    Zhao Wei He Ning Li Liang
    2006, 34(7):  40-44. 
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    In order to correctly analyze the effect of enhanced cooling of the cutting media in the metal-cutting process, the orthogonal cutting process of aeronautical Ti6Al4V alloy in the enhanced cooling condition is simulated using a commercial finite element software Deform-2D, and the formation processof the serrated Ti6Al4V chips is simulated by geometric modeling, meshing, boundary condition setting and materialmodeling, etc. The chip for-mation, cutting force and cutting temperature in different enhanced cooling conditions are then analyzed and dis-cussed. The results indicate that, with the increase in heat exchange coefficient, the mean rake temperature de-creases, while the maximum cutting temperature and the cutting force change little.

    Chen Yang-zhi Xing Guang-quan Liu Wen-guang Yao Hua-ping
    2006, 34(7):  45-49. 
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    A novel drive mechanism named micro-elastic mesh wheel was developed to transfer power between the cross axes in a limited space by in-tube micro robot. During the investigation, a mechanical model of the novel drive mechanism was established based on the large deformation theory in themechanics of materials, and themaxi-mum transmission force of the mechanism was formulated and calculated. Experiments are finally carried out on a micro-force test platform to test the transmission force. The calculated and experimental results show that the pro-posed drive mechanism fully meets the requirements of power transfer to micro robot in tube.

    Hua Tong-shu Shen Xue-jin Chen Xiao-yang
    2006, 34(7):  50-54. 
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    In the trunnion bearing of a Hooke’s universal joint,the crown drop on the needle roller determines thecontact pressure distribution between the needle and the raceway,and is one of the most important factors to affect the capability and life of the joint. In order to improve the capability of Hooke’s universal joints,the effects of structural parameters on the contact pressure distribution are analyzed based on Lundberg’s logarithmic equation and the numerical calculation of three-dimension elastic contact problems in finite length. It is suggested that,in the design of crown drop,both the chamfer radius and the grinding undercut width should be considered. More-over,the corresponding numerical method to calculate the crown drop is presented,by means of which the trunnion bearings can be designed without the“edge effects”of the contact pressure distribution and the high-pressure con-centration in the contact region. As a result,the capability and service life of the designed Hooke’s universal joint are improved.

    Mathematical Sciences
    Shen Yao-tian Li Zhou-xin
    2006, 34(7):  120-123. 
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    This paper considers the solutions to the Dirichlet problem in a class of p-Laplacian equation. In the condition weaker than the(AR)condition,the corresponding functional of the equation is first proved satisfying the (PS)c condition. Then,by applying the Mountain Pass Theorem,the existence of infinitely many solutions of the problem is confirmed.

    Yao Qing-liu Li Yong-xiang
    2006, 34(7):  124-127. 
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    The existence of the solution to a class of nonlinear fourth-order elastic-beam equation is investigated. This class of equation,whose nonlinear terms contain a three-order derivative of the unknown function,mechanical-ly describes the deformation of an elastic beam,one end of which is fixed and the other is clamped by sliding clamps. In the investigation,the decomposition technology of boundary-value problems is adopted to transform the elastic equation into a fixed-point equation. Besides,four existence theorems of the solution to this class of equation are presented by constructing a suitable Banach space and by means of Leray-Schauder fixed-point theorem. The re-suits show that this class of equation possesses at least one solution or one positive solution if the“height’’of its nonlinear item is appropriate in a bounded set.

    Song Chang-xiu Weng Pei-xuan
    2006, 34(7):  129-132. 
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    This paper deals with the boundary-value problems of a class of fourth-order nonlinear functi0hal differen-tial equation. By transforming the boundary-value problem into the corresponding fixed-point problem of a complete-ly continuous operator,the sufficient condition for the existence of the positive solutions to the problem is given via the fixed-point theorem in cones and the inequality evaluation technology. Thus,the existing results of the boun-dary-value problem for the corresponding ordinary differential equation are extended. The applicability of the ob-tained results is finally proved by examples.

    Architecture & Civil Engineering
    Wei De-min Bian Jian-feng
    2006, 34(7):  69-76. 
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    Under the fluctuating wind load,the wind-induced vibration response of the single-layer reticulated shell structures is different from that of tall buildings,because the main mode contributory to the dynamic response is usually not the 1st vibration mode,but the combination of the first tens of modes. Hence,it is necessary to find the contributory modes to the response. In this paper,the quasi-mode method considering the resonance response of the high modes is used to analyze the wind-induced vibration response of single-layer cylindrical reticulated shells,the effects of such factors as the self-vibration frequency and the damp ratio on the resonance response are investigated,and the vibration mode number needed for calculating the quasi-mode is discussed. The results show that the mode
    cross-correlation must be taken into consideration because the self-vibration frequencies are very close to one ano-ther. Moreover,the factors to influence the mode cross-correlation and the vibration mode number needed for calcu-lating the cross-correlation are presented,followed by the wind-induced vibration coefficients of the displacement and the axial force for a practical single-layer cylindrical reticulated shell.

    Shi Yong-jiu Li Qiu-zhe Wang Yuan-qing Yang Lu
    2006, 34(7):  77-81. 
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    In the plastic stage,the composite-slim beam with deep rib is of a complex stress distribution in its sec-tion,so the existing calculation methods of bending resistance depend greatly on engineering experiences. In order to solve this problem,a method,equivalent rectangular stress distribution,is proposed based on the experiments conducted on two simply-supported composite-slim beam specimens. A model for calculating the bending resistance of the beam is then established and the corresponding formulae are derived. Moreover,a reduction coefficient for concrete peak stress is suggested on the basis of the existing experimental results,preliminarily confirming the cor-rectness of the proposed formulae.

    Wu Bo Hong Zhou
    2006, 34(7):  82-87. 
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    A full-process analytical program for the simply-supported normal-strength concrete (NSC) and high-strength concrete (HSC) beams subjected to high temperature is proposed, in which the explosive spalling of HSC is approximately taken into consideration. The reliability of the program is validated by the test results provided by former researchers. Then, the effects of the main parameters on the fire resistance of simply-supported NSC and HSC beams are investigated and compared, by selecting 288 simply-supported beams with different load ratios, thicknesses of concrete cover, span-depth ratios and reinforcement ratios for the high-temperature response analy-sis. Based on the simulation results, simplified ways to quantificationally determine the fire resistance of simply-supported NSC and HSC beams are presented. The results show that the explosive spalling at a high temperature significantly influences the fire resistance of simply-supported HSC beams, and that the fire resistance of both HSC beams and NSC beams can be effectively improved by strictly controlling the load ratio and properly increasing the thicknessof concrete cover.

    He Chun-bao Ca Jian Lin Fan
    2006, 34(7):  88-93. 
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    In this paper,by taking the superstructure rigidity into consideration,a semi-analytical and semi-nume-ileal solution to the interaction between grillage beam foundation and subsoil is obtained based on the elastic beam theory and the Boussingesq solution. In the process of working out the solution,the grillage foundation on elastic subsoil is regarded as a composite system of beams in two directions. The superstructure is simplified as a plate with equivalent rigidity,and the force and the displacement among beams,slabs,columns and the gmund are compati-bly analyzed. It is proved by numerical examples that the proposed method is of high precision with less unknown data and it is convenient for practical engineering.

    Yuan Bing Huang Yan-sheng Ren Li-fei Liang Fang-hui
    2006, 34(7):  94-98. 
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    In order to investigate the seismic torsional response of base-isolated structures with frame-shear walls,the lateral-torsion coupling vibration model and the corresponding motion equation are formulated for the high-storey structure with frame-shear wall and isolated foundation under seismic action. The lateral-torsion eoupling seismic response of the uniaxial-eccentricity base-isolated structure is then analyzed,and the seismic responses of several base-isolated structures with various eccentricity ratios are discussed. The results show that the eccentricitv ratio of the superstructure to the base-isolated layer should be reasonably adjusted in the design of a structure,and that the torsional response of the base-isolated structure can be obviously reduced only when the eccentricity ratio satisfies a certain condition.

    Pan Dong-hui Cai Jian Lin Fan
    2006, 34(7):  99-103. 
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    The response modification factor is introduced to evaluate the seismic capacities of the reinforced con-crete(RC)shear walls of tall buildings,and to quantitatively articulate the seismic fortification measures pre-scribed by the China codes. The overstrength and ductility factors of an independent rectangular cantilever shear wall are also analyzed and calculated. Thus,the response modification factors for the shear walls with different seis-mic grades are determined,which are then compared with the ground motion ratio of the moderate intensity earth-quake to the frequently occurring earthquake. The results show that the seismic grade,the aspect ratio,the axial compression ratio and the wall length are the main variables affecting the seismic capacity,and that the aspect ratio should be limited to insure the seismic capacity. The limitation of aspect ratio and the corresponding design sugges-tions are finally proposed for the shear walls with different seismic grades.

    Huang Ye-qing Sun Yi-min
    2006, 34(7):  104-108,114. 
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    This paper deals mainly with the way to create memorial places integrated with surroundings by sum-ming up the planning scheme of the memorial park of Ye Jian-ying. Based on the thoughts of integrating memo-rial places with surroundings,the natural environmental elements are fully considered and organically harmo-nized with the thematic spots of a memorial place,and the abstracted unique natural environmental characteris-tics are integrated with the functions of the memorial place,thus resulting in an organic and tight integration of the newly-built memorial place with the unique natural surroundings.

    Chen Ming-zheng Huang Yin Wang Zheng-lin Bai Shao-liang
    2006, 34(7):  109-114. 
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    According to the loading characteristics of bonded post-tensioned prestressed concrete frames,a program is worked out to perform a nonlinear finite element analysis for the static staff in both the stretching wire stage and the loading stage. In working out the program,the relationship between the stress and the strain of the material is directly employed,the tension hardening and compression softening of concrete are considered,the sectional lay-ered finite element model and the arc-length method are adopted,and both the material nonlinearity and the geo-metric nonlinearity are taken into account in the stiffness matrix. As compared with the experimental results of two prestressed concrete frames,the simulated results obtained by the program are of high precision,meaning that the proposed program is suitable for the calculation and analysis of bonded post-tensioned prestressed concrete frames.

    Zeng Qing-jun Mo Hai-hong Liao Jian-chun Huang Teng
    2006, 34(7):  115-119. 
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    The investigation into the mechanical properties of field soil-cement mixed with silt or mucky soil can di-rectly provide useful data for the design and construction of soil-cement mixing piles in the Delta of the Pearl River. In this paper,the field soil-cement with one-day age was drilled and sampled. The samples were then cured for dif-ferent ages,followed by the measurements of the physical and mechanical properties,including the unconfined compression strength,the shear strength and the compression modulus. Therefore,the growth laws and influencing factors of the strength of field soil-cement were obtained,thus coming to the conclusion that the unconfined com-pression strength of the field soil-cement obviously increases with the age to about half of that of the soil-cement pre-pared in laboratory at the age of 28 days,that the compressive coefficient of the field soil-cement mixed with silt reaches a medium degree at the age of 28 to 90 days,namely,0.1 to 0.4 MPa-1,and that the unconfined compres-sion strength of the field soil-cement is 0.4 to 1.1 MPa at the age of 90 days,which is 20.9 to 57.6 times that of
    the undisturbed soil.

    2006, 34(7):  0. 
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