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Table of Content

    25 September 2009, Volume 37 Issue 9
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    Architecture & Civil Engineering
    Influence of Random Characteristics of Strengths of Steel Bar and Concrete on Fire Resistance of Column at High Temperature
    Wu Bo Liang Yue-huan
    2009, 37(9):  1-6. 
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    In order to reveal the influence of random characteristics of the relative steel bar/concrete strength on the fire resistance of column at a high temperature,the fire resistance of column is calculated according to the average curve of the relative strength versus the temperature.The results show that,with the increase in the eccentricity ratio of load,the effect of the random characteristics of the relative yield strength of steel bar at a high temperature on the fire resistance of column continuously improves and the variance coefficient of the fire resistance of column gradually increases from 0. 003 to about 0. 060, that, though the influence of the random characteristics of relative strength of concrete at a high temperature continuously decreases, the variance coefficient of the fire resistance of column averages out at about 0. 050, and that the fire resistance of column distributes in a normal mode.

    Mechanical Behavior of Reinforced Concrete Frame Structure with Diagonal Members
    Cai Jian Zhou Fei Su Guang-qun Wang Li-jia Zuo Zhi-liang
    2009, 37(9):  7-12. 
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    A new kind of reinforced concrete（RC） frame structure with diagonal members is put forward,and the mechanical behavior of the new structure under vertical and horizontal loads is analyzed and compared with that of the conventional RC frame structure.The results indicate that the principal design sections of the new frame structure are located at the beam-diagonal member joint,the column-diagonal member joint and the column bottom,and that both the bending moments and the shearing forces of the new structure at the ends of beam and column greatly reduce. Moreover, the loading experiments and nonlinear finite element analysis of the large-size new structure shows that, in loading conditions, the plastic hinge appears first at the beam-diagonal member joint, then at the middle of the beam, that the ends of beam and column as well as the beam-column joint, all exhibit good mechanical behaviors, and that a reasonable design may provide the structure with good bearing and deformation capacities.

    Neumann-Expansion Response Surface Method for Calculating Structure Reliability
    Su Cheng Li Peng-fei Han Da-jian
    2009, 37(9):  13-17，23. 
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    When structure performance functions can not be explicitly expressed as the analytical expressions of random variables,the response surface method（RSM） becomes effective in reliability analysis.However,RSM is of low efficiency because it requires multiple determinate finite-element numerical tests.In order to solve this pro-blem,an improved RSM,namely the Neumann-expansion response surface method（NERSM）,is proposed.In this method,the computation time of finite-element numerical tests is effectively shortened by introducing the Neumann series expansion, thus improving the computation efficiency. Numerical examples show that, as compared with the conventional RSM, the NERSM is of higher computation efficiency without reducing the computation accuracy when the scale of the structure stiffness matrix becomes larger.

    Method to Analyze Wrinkled Membranes by Using Local Coordinate Transpose and Equivalent Stiffness
    Zhao Ran Wei De-min Sun Wen-bo
    2009, 37(9):  18-23. 
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    In the load analysis of membrane structures,incorrect compressive stresses exist in one-way wrinkled and slack membranes,so that wrinkling analyses should be performed in the calculation process of the structures.This paper proposes a new method to analyze wrinkled membranes by using the local coordinate transpose and the equivalent stiffness,and presents the corresponding program based on the finite element software Strand7 and its application program interface Strand7API.The program is then used to analyze the whole-process response of a typical membrane structure under vertical loads. The results indicate that, after the iterative calculation, the proposed method makes the second principal stress basically be zero, correctly deals with wrinkled membranes, and helps to obtain the actual load responses of membranes after the emergence of wrinkles.

    Whole-Process Analysis of PC Multi-Girder Bridge Based on Ottosen s Criterion
    Zhang Jian Ye Jian-shu Yu Bo
    2009, 37(9):  24-29. 
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    This paper aims at the nonlinear whole-process analysis of prestressed concrete（PC） multi-girder bridges.In the investigation,first,nonlinear variations of the concrete including cracking,yielding and crushing are described respectively based on the smearing crack model,Ottosen s yielding criterion and the Hinton crushing theory.Next,with the help of degraded shell element,the concrete and the common steel are simulated using the layered shell element and the prestressed steel is simulated using the combined shell element. Then, the contribution of the prestressed steel to the stiffness matrix of the combined shell element is investigated according to the displacement coordination. Moreover, a nonlinear combined-layered shell element model is established and the corresponding analytical procedure is programmed, by which a 3D nonlinear calculation is performed, finding that the calculated results accord well with the results of failure experiment of a PC multi-girder bridge, with a relative error of the ultimate bearing capacity of about 0. 13%. Finally, the regularities of stress redistribution of the prestressed steel and the common steel are analyzed, showing that the proposed nonlinear shell element with excellent numerical stability and convergence is suitable for the whole-process analysis of thin-wall structures such as PC multi-girder bridges.

    CFD Approach to Evaluation of Wind Energy in Complex Terrain
    Xiao Yi-qing Li Chao Ou Jin-ping Song Li-li Li Qiu-sheng
    2009, 37(9):  30-35. 
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    To evaluate the wind energy distribution in a complex terrain which is impossible to be done by using traditional methods,two strong wind events with stable wind direction were selected from the field record of a real complex terrain and were used as the researching objects.Then,the wind field in the terrain was meshed into hexahedral grids with two resolutions of 40m×40m and 20m×20m,and two turbulence models,namely SST k-ω and RNG k-ε,were adopted to simulate the wind speed field distribution.The simulation results of the wind indicate that SST k-ω model is superior to RNG k-ω model because it is of higher accuracy of the grid with a horizontal space of 20 m, and that, in the case of SST（20 m） , the mean relative errors between the simulated and the measured wind speeds in 157° and 83° directions are respectively 6.46% and 5.50%. The authors also proposed a fulldirection wind energy evaluation method applicable to complex terrains, which takes into consideration both the wind speeding ratio distribution obtained from CFD simulation and the local normal meteorological data.

    Remediation of Historic Marble Architectural Heritages by Bacterially-Induced Biomineralization
    Li Pei-hao Qu Wen-jun Xu De-qiang Xiao Yi-ping
    2009, 37(9):  36-41. 
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    In order to avoid irreversible damages to historic architectural heritages caused by incorrect protection processes,the method of bacterially-induced calcium carbonate mineralization was adopted to form a deposition la-yer on the surface of marble samples.Then,the effects of crystal phase and growth of the mineralized layer as well as the deposited crystal on the porosity of samples and on the efficiency of bonding and protection were analyzed by means of XRD,SEM,mercury intrusion porosimeter（MIP） and ultrasonic test. Experimental results show that the mineral crystal is composed of calcite and vaterite phases, that bacteria act as nucleation sites in the precipitation of the mineral crystal uniformly depositing on the sample surface, that the precipitation has no significant effect on the pore size distribution of samples rather than results in a porosity decrease by 22.2% , and that the mineral crystal strongly attaches the substratum. It is thus concluded that the bacterially-induced biomineralization is effective in remediating historic stone architectural heritages.

    Electronics, Communication & Automation Technology
    Distributed Source Coding Algorithm Based on Low-Density Parity-Check Code
    Jiang Yan Pan Wei-qiang Ning Geng-xin Wei Gang
    2009, 37(9):  42-46. 
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    In order to make full use of the correlations of sources in the information collection network,and to breakthrough the limitation of memory and computing capabilities of information-collecting equipment,a distributed source coding algorithm based on the low-density parity-check code（LDPC） is proposed,which transfers the co-ding complexity to the decoder and effectively reduces the source coding complexity without reducing the output quality of the decoder.The algorithm aims at Gaussian sources,implements with EDPC, and is based on the coset partition principle. Experimental results show that, as compared with Trellis and Turbo codes, the proposed algorithm is simpler and more intuitional, with obvious advantages in the case of low correlated signal-to-noise ratio, and that, at a symbol error rate of 10-3, the signal-to-noise ratios increase by about 3.0 -3.5 dB and 0. 7 dB, respectively.

    A Modified BIC Algorithm of Speaker Change Detection
    Yang Ji-chen He Qian-hua Pan Wei-qiang Xu Yi-jun Li Yan-xiong
    2009, 37(9):  47-51. 
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    In order to overcome such disadvantages as high computational cost and low detection precision existing in the speaker change detection with the Bayesian information criterion（BIC） algorithm,a modified BIC algorithm is proposed.In this algorithm,the maximum length of the first data window in the analysis window is restricted to reduce the computational cost,and the effective length,namely the detectability of the second data window in the analysis window is increased to improve the detection precision.Moreover, the growing computation without a long time speaker change is decreased by detecting potential speaker change points only in a new range. Experiment resuits show that, as compared with the conventional BIC algorithm, the proposed algorithm decreases the bias error from 0. 10 -0. 80 to 0. 03 - 0. 20, and saves 75 % of computation time for a 40-s analysis window.

    Design and Analysis of a Novel SCRLH Transmission Line Structure
    Gong Jian-qiang Chu Qing-xin
    2009, 37(9):  52-56. 
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    In order to realize a relatively wide impedance matching bandwidth,the traditional composite right/left-handed（CRLH） transmission line（TL） must operate in a balanced state,in which a seamless transition exists between the left-handed and the right-handed passbands.However,it is difficult to satisfy such a balanced condition in practice.To solve this problem,a novel simplified CRLH（SCRLH） TL structure is proposed.The novel structure is similar to the bandpass filter in property,that is,the attenuation constant keeps zero with a continuous and smooth characteristic impedance distribution within the passband, the bandwidth may be wideband or even uhrawide band, and the characteristic impedance is respectively a real number within the passband and a pure imaginary with the inhibition of electromagnetic wave propagation outside the passband. Then, a practical microstrip SCRLH TL structure with the center frequency locating at 6.85 GHz and the relative bandwidth of 110% is implemented by adopting the microstrip high/low-impedance lines and the grounded stub, and its transmission properties obtained from full-wave/circuit simulation analyses and experimental measurement accord well with each other. In addition, the dispersion characteristics extracted from the above-mentioned transmission properties approach the theoretical ones well, which justifies the feasibility of the novel SCRLH TL structure and its potential application prospects in the design of ultra-wideband filter.

    Arbitration Strategy Based on Early Arbitration and Request Waiting Priority
    Yang Jun Cao Yang Ma Qin-sheng Gao Xun
    2009, 37(9):  57-61. 
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    In order to solve the contradiction between the performance and the cost of arbitration scheduling in the multi-port System-on-Chip,a new arbitration strategy expanding the mechanisms of early arbitration and request waiting priority on the fixed priority arbitration algorithm is proposed.In this strategy,the mechanism of early arbitration is used to decide a new bus access request according to the duration of data transfer,and the mechanism of request waiting priority is employed to set the request waiting time for the port that bus access requests turned down by the arbiter. When the waiting time expires, an access priority is provided for the port. Experimental results indicate that, as compared with the arbitration strategy based on request waiting priority, the proposed strategy increases the bus utilization by about 10% ; and that it considers both the priority and the fairness of the ports and possesses high system performance with tow cost.

    A Data Coding Method for Transmitting Implantable Neural Control Signals
    Wu Zhao-hui Liang Zhi-ming Li Bin
    2009, 37(9):  62-66. 
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    In the transmission of neural control signals to the internal module of a implantable neural-signal acquisition system using the differential coding method,high clock synchronization between the internal and the external systems is required,which makes the circuit design extremely difficult.In order to solve this problem,a new data coding method is presented.In the external module,control signals coded by pulse-width modulation are transmitted to the internal module through binary phase shift keying（BPSK）modulation and demodulation, and the clock detector, clock divider, pulse width counter and pulse logic judger are used to decode the signals. Thus, both the internal and the external modules can work at asynchronous system clock frequencies, and the circuit design and verification are greatly simplified. The new coding method has been successfully applied to a board circuit system for wireless implantable neural-signal acquisition, and the waveform test results verify the feasibility of the method. Moreover, no error has been found in the transmission test of 1 000 000 B random data produced by a M-sequence generator, thus coming to the conclusion that the proposed coding method is highly reliable.

    Design of Low-Clock Jitter VCO with Strong Ability of Rejecting Power Supply Noise
    Cai Min Wang Dong-chun
    2009, 37(9):  67-70，81. 
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    A kind of ring voltage-controlled oscillator（VCO） based on the current steering logic is designed,and the conventional cascode bias circuit is improved by introducing a amplifier with large voltage gain to constitute a new active negative feedback structure with strong ability of rejecting power supply noise.Then,a contrast simulation of the conventional VCO and the improved one is conducted with HEJIAN 0.18μm twin-well CMOS technology.The results indicate that the peak-peak jitter and the RMS（Root Mean Square） jitter of the conventional VCO are respectively 54. 135 ps and 19. 454 ps under the high-frequency power supply noise with a frequency of 20 MHz and a peak-peak amplitude of 0. 2 V, while the corresponding values of the improved VCO are respectively 27. 442 ps and 9. 196 ps, which reveals better jitter performance of the improved VCO. Moreover, the improved VCO is of an output frequency of650MHz, a duty cycle of about 52%, a voltage gain of 962. 16 MHz/V for a central control voltage of 0. 9 V with good linearity, and a low power dissipation of only about 0. 7 mW in 1.8 V DC power supply.

    A Phase-Locked Loop of Fast-Locking Charge Pump with Low Power Consumption
    Wei Jian-jun
    2009, 37(9):  71-76. 
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    In order to speed up the startup of phase-locked loop（PLL）,an initialization circuit is proposed,which stops working after the startup has been finished and consumes little power.Then,a phase-frequency detctor（PFD） with saturated output is proposed to extend the working range of PFD.Moreover,a logic circuit is applied to directly control a standard counter and to simplify the pulse-swallow frequency divider into a single loop,thus saving a counter without increasing the power consumption.Finally,the standard CMOS logic process of 0. 18 μm 1.8 V 1P6M N trap is applied to the design with a layout area of 0. 08mm2. Simulated results show that the application of both the initial circuit and the PFD with saturated output results in a decrease of locking time by 19% , and that, at a frequency of 266 MHz, the relative peak-peak jitter of the output signal is less than 2.5% and the total power consumption of the PLL is about 17 mW.

    Implementation of High-Speed Communication Chain for Embedded Integrated Navigation System
    Zhang Guo-long Xu Xiao-su
    2009, 37(9):  77-81. 
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    In order to meet the requirements of miniaturization,low power consumption,low cost and high precision of the embedded integrated navigation system based on the digital signal processor（DSP）,single field programmable gate array（FPGA） chip was used to control each logic module,expand the multi-channel universal asynchronous receiver transmitter（UART） and design double first-in-first-out（FIFO） memories for the data buffering of UART.In addition,for the purpose of reducing the additional CPU overhead for transmission, a Ping-Pong Buffer storage was designed in the random access memory （RAM） of DSP, and the enhanced direct memory access （EDMA） provided by TMS320C6713 was used to transmit data between the FIFO of UART in FPGA and the Ping-Pong Buffer storage. Test results indicate that the proposed scheme makes the multi-channel UART steadily operate at 460. 8 kb/s with the control of EDMA when CPU executes navigation algorithms at the same time. Thus, a high-speed communication chain between DPS and peripheral equipment is successfully implemented and CPU can be devoted further to navigation algorithms.

    Mechanical Engineering
    Formation Mechanism of 3D Integral-Fin on Outer Wall of Copper Tube by Composite Machining
    Xiang Jian-hua Tang Yong Ye Bang-yan Zhou Wei Wan Zhen-ping
    2009, 37(9):  82-87. 
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    A kind of third-generation enhanced heat-transfer component,namely 3D integral fin,was machined by the rolling-ploughing-extrusion composite machining,and the corresponding formation characteristics,machining conditions and formation mechanism were analyzed.Experimental results show that,at a rolling depth and a plou-ghing-extrusion（P-E） depth of both 0.20mm,a rotational speed of 50r/min and a feed rate of 0.16mm/r,optimal 3D fins with the height of 0.25mm can be machined on the outer wall of the red copper tube which is 16 mm in diameter and 1.5 mm in wall thickness. Analytical results indicate that there is a matching relationship not only between the rolling depth and the rotational speed but also between the feed rate and the P-E depth, that two different fin structures can be obtained in different machining conditions. One is the composition of V-shaped and U-shaped grooves, and the other is of only V-shaped grooves, and that 3D integral fins can be machined by the rolling-ploughing-extrusion composite machining when single V-shaped grooves are formed by both rolling and P-E processing.

    Identification Method of Welding Seam Offset Based on Support Vector Regression Machine
    Zeng Song-sheng Shi Yong-hua Wang Guo-rong
    2009, 37(9):  88-92. 
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    In order to improve the identification precision of welding seam offset,first,the welding current signals based on the rotational arc sensor are filtered by wavelet,followed by the reconstruction of a sample data set via the pretreatment.Next,an extension algorithm of Laplace feature mapping is proposed based on the support vector regression（SVR） machine,which is applied to the dimensionality reduction of the sample data set and the new sample.Then,the sample data set after the dimensionality reduction is used to train the SVR machine and identify the offset for the new sample. Finally, the proposed identification method is compared with the traditional method without dimensionality reduction. Experimental results indicate that the dimensionality reduction based on Laplace feature mapping may result in an average increase of identification precision by 25 %.

    Compensation Control of Springback Torsion for 3D Irregular Stamping Parts
    Liu Qiang Ruan Feng Xue Xin Zhou Chi
    2009, 37(9):  93-97. 
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    A compensation control method of springback torsion based on the deformation transfer function（DTF） is proposed for a special kind of 3D irregular stamping parts.In this method,the relationships among part sections are evaluated according to the relative torsion angle variation of inertial principle-axis vector,and the transfer function between the simulated and the experimental relative torsion angle deviations is deduced based on the DTF method,which is then used to design the die face.The application of the proposed compensation control method to the formation of a spiral blade sheet indicates that the method keeps the integral space torsion error of the blade sheet under 5%, guarantees the quality of contact surface of adjacent blade sheets in the integral welding process, and overcomes the difficulty in the installation due to the insufficient torsion between two sections.

    Robust Positioning Algorithm of Lead-Free Solder Joints Based on Gray-Level Integration Projection
    Wu Fu-pei Zhang Xian-min Kuang Yong-cong Ouyang Gao-fei
    2009, 37(9):  98-102，116. 
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    In order to avoid the misjudgement of automatic optical inspection system due to the positioning error of solder joints,a robust positioning algorithm of solder joints is presented based on the gray-level integration projection.In this algorithm,first,solder joints are segmented from the printed circuit board（PCB） image after the binarization of the pretreated image of lead-free solder joints according to the color feature of the joints.Then,with the help of gray-level integration projection curves of solder joint features in both horizontal and vertical directions,the positioning coordinates of the joints are obtained and the accurate positions of the joints can be determined by maximizing the pixel area of solder joints within the solder-land windows. Moreover, by introducing a Blob evaluation function, the solder joint and the noise are differentiated, thus effectively reducing the disturbance of noise and improving the robustness of the algorithm. Experimental results show that the proposed algorithm is of a high positioning precision less than 1 pixel for various solder joints of a Chip component.

    Data Registration Method for Multiple-Sensor Integrated Measurement System
    Liu Peng-xin Wang Yang
    2009, 37(9):  103-107. 
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    At present,the precision of data registration of multiple-sensor integrated measurement system（MIMS） completely depends on the measurement accuracy of geomatric references,and the registration process is complex and not flexible.In order to solve these problems,an automatic registration algorithm is proposed which does not require any primitive artifacts as data.In this algorithm,first,the curvatures of point sets are calculated,and three pairs of points with similar curvature are selected to compute the transform matrix for an initial registration. Next, in order to obtain the corresponding points, the point sets obtained by contact measurement are projected to the triangular meshes constructed from the triangulation of non-contact scanning point cloud. Then, the coordinate transformation is achieved using a iterative method, which helps to implement the registration of the point sets without corresponding points. Finally, the intersection of bounding box is utilized to merge data into one set. Experimental resuits show that the proposed algorithm insensitive to the initial position improves the registration precision, reduces the manual intervention in the registration process and results in a maximum and a minimum least square registration errors of 0. 045 and 0. 025 μm, respectively.

    Experimental Investigation into Wear Process of Steel Worm Wheel Pair
    Li Zhu-jun Shao Ming Zhang Da-tong Li Yuan-yuan
    2009, 37(9):  108-111. 
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    In order to select a reasonable hardness matching for prolonging the service life of steel worm wheel pairs used in mechanical track tension adjustors,a experimental method was designed to evaluate the effect of hardness on the wear behaviors of steel worm wheel pairs on a SRV Ⅳoscillating friction and wear tester.By using this me-thod,the wear behaviors of the worm wheel pairs with different hardness matching of 40CrNiMoA steel and 18Cr2Ni4WA steel were investigated in unlubricated condition at a room temperature. Experimental results show that, in the steel worm wheel pairs composed of 40CrNiMoA steel and 18Cr2Ni4WA steel, the wear volume of 40CrNiMoA steel decreases, while that of the worm material 18Cr2Ni4WA steel increases with the increase in hardness of 40CrNiMoA steel, and that, in the applied 18Cr2Ni4WA steel have approximately equal service experimental conditions, both the 40CrNiMoA steel and the life when the hardness of 40CrNiMoA steel is about HRC43.

    An Entropy-Based Hybrid Genetic Algorithm for Job-Shop Scheduling
    Chen Yao-jun Yao Xi-fan Zhang Qing
    2009, 37(9):  112-116. 
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    To improve the searching performance of job-shop scheduling algorithms,the population entropy for eva-luating the orderliness（difference） of the algorithm population is proposed by analyzing the convergent graph of the simulated annealing genetic algorithm.Then,a modified simulated annealing genetic algorithm is proposed based on the population entropy,which adapts itself to the variation of population via the dynamic change of both the crossover probability and the mutation probability with the population entropy. Thus, the population diversity is increased, the premature convergence of the algorithm is overcome, and the searching performance is improved. Simulated results show that the proposed algorithm has great superiority in the searching performance. As compared with the traditional genetic algorithm, in the same initial and convergence conditions for the FT10 problem, the optimal result is improved from 998 to 930 and the deviation reduces from 9.78% to 1.94%, while for the LA36 problem, the optimal result is improved from 1 359 to 1 278 and the deviation reduces from 10. 29% to 2.97%.

    Experimental Investigation into Deposition Uniformity of Laminated Template Electrodeposition
    Fan Hui Tian Zong-jun Huang Yin-hui Liu Zhi-dong
    2009, 37(9):  117-122. 
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    In order to improve the deposition uniformity of laminated template electrodeposition（LTE） and to further simplify the auxiliary operation,three kinds of current configurations including direct current（DC）,anodic pulse current（PC） and pulse-reverse current（PRC） were respectively applied to LTE test,and such parameters of pulse-reverse current as pulse width,pulse frequency,working time,turn-off time and current density were modulated and optimized.Then,the thicknesses and micro-morphologies of the metal layers deposited with different current configurations were compared, finding that PRC offers better deposition uniformity, easier LTE operation and lower time cost. Finally, the function of PRC in diminishing surface roughness was theoretically analyzed, and a batch of copper parts, which are 20 mm × 20 mm in section size and 4mm in thickness, were deposited in optimized PRC conditions. The results verify the feasibility of the LTE with PRC.

    Chemistry & Chemical Engineering
    Influences of H2S Content and Flowrate on Performance of Fuel Cells
    Zhong Li Chuang Karl
    2009, 37(9):  123-127. 
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    Nano-sized composite proton-conducting membrane of Li2SO 4＋Li2WO 4＋Al2O3was prepared via the sol-gel method,and the electrochemical performance of the fuel cell with the configuration of H2S,（composite MoS2 anode catalyst）/composite proton-conducting membrane/（composite NiO cathode catalyst）,air was investigated at various H2S content,volume flowrate and operation temperature.Moreover,the performances of MoS2 and composite MoS2 anode catalysts were analyzed by comparison.Experimental results show that the voltage, output current and power density of the fuel cell all increase with H2S content and flowrate in the gas mixture due to the improvement of gas diffusion in the anode and due to the increase in the concentration of anodic electroactive species. Thus, the electrochemical performance of the fuel cell becomes better. It is also indicated that, even if the H2S content is less than 5% （mole fraction）, H2S can also be used as the fuel for power generation, that not only the electrical conductivity and electrochemical reaction rate of the proton-conducting membrane but also the output current and power density of the fuel cell increase with the temperature, that the composite MoS2 anode catalyst is superior to the MoS2 anode catalyst in terms of performance and chemical stability, and that, when pure H2S with a flowrate of 35 mL/min is input in the anode compartment and the air with a flowrate of 100mL/min is input in the cathode compartment, the fuel cell with composite MoS2 anode catalyst is of the maximum power densities up to 12.4, 52.9 and 130mW/cm2 and the maximum current densities up to 45, 281 and 350mA/cm2 respectively at 650, 700 and 750 ℃.

    Fixed-Bed Adsorption of Gaseous Trichloromethane on Three Kinds of Activated Carbons
    Xia Qi-bin Huang Si-si Xiao Li-min
    2009, 37(9):  128-132. 
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    In order to investigate the adsorption capability of trichloromethane on activated carbons,the breakthrough curves of the fixed-bed adsorption of trichloromethane on three kinds of commercial activated carbons were measured,and the pore structures and specific surface areas of the activated carbons were characterized.Moreover,the effects of operation conditions and pore structures on the adsorption capacities of trichloromethane on the commercial activated carbons were discussed.Experimental results indicate that the breakthrough time prolongs not only with the decrease in the trichloromethane inlet concentration and the adsorption temperature but also with the increase in the loading length of the fixed bed, that both the BET specific surface area and total pore volume of the activated carbons decrease in the order of SY-9 〉 Tianda 〉 SY-16, that the adsorption capacities of trichloromethane on SY-9 and Tianda activated carbons are respectively 1.80 and 1.43 times that on SY-16 activated carbon when the adsorption performs at 298.15 K with a trichloromethane inlet concentration of 9. 497 g/m3, an adsorption column length of 2.4 cm and a line speed of carrier gas of 15.28 m/min, and that the ratio of adsorption capacities is similar to that of specific surface areas, meaning that trichloromethane is mainly adsorbed in the micropores of the activated carbons.

    Synthesis of Fluorinated Emulsifier-Free Polyacrylate Emulsion in the Presence of Polymerizable Emulsifier
    Xiao Xin-yan Wang Ye Wan Cai-xia
    2009, 37(9):  133-138. 
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    Fluorinated emulsifier-free polyacrylate emulsion with a core-shell structure was synthesized via the pre-emulsified seed emulsion polymerization,with methyl methacrylate（MMA）,butyl acrylate（BA） and hexafluorobutyl methacrylate（HFMA） as the main monomers,and with ammonium allyloxtmethylate nonylphenol ethoxylates sulfate（DNS-86） as the polymerizable emulsifier.Then,the influences of the dosages of DNS-86 and HFMA on the electrolyte stability of the emulsifier-free emulsion and on the water resistance of the film were discussed. Moreover, the emulsion and the film were characterized by means of FT-IR, TEM, DSC, contact angle method and TG. The results show that, as compared with the traditional complex emulsifier OP-10/SDS, polymerizable emulsifier DNS-86 may result in stronger electrolyte stability and water resistance in the polymerization with 2.2% DNS-86 and 8% HFMA, that HFMA effectively participates the emulsion copolymerization, that there exists a clear coreshell structure in emulsion particles, that the emulsifier-free emulsion film is of two glass transition temperatures, namely 261.11 and 300.48 K, which respectively correspond to the core-phase and the shell-phase copolymers, and that, at a HFMA dosage of 8%, the water contact angle of the film-air interface reaches 94.1 ° and the decomposition temperature of the emulsifier-free emulsion film is 48 K higher than that of the traditional polyacrylate emulsion film, showing a greatly-improved hydrophobie property and thermal stability of the film.

    Synthesis and Properties of Microencapsulated Phase Change Materials by In-Situ Polymerization
    Yan Ying Liu Jian Zhang Hui-ping
    2009, 37(9):  139-143. 
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    In this paper,first,microencapsulated phase change materials were synthesized by the in-situ polymerization,with urea-formaldehyde resin as the shell and with RT31 paraffin as the core.Next,the effects of different emulsifiers on the morphology and thermal properties of the microcapsules were analyzed by means of SEM,DSC and optical microscopy.Then,the average particle size and its distribution as well as the thermal properties of the microcapsules at different emulsifier dosages and rotation speeds were analyzed. Finally, the morphology of the microcapsules varying with the acidification time was observed. Experimental results show that, when the complex emulsifier is composed of 52% （mass fraction, the same below） Tween 60 and 48% Span 60, the microcapsules made from 5% complex emulsifier at the rotation speed of 3000r/min are of uniform particle size, smooth and well- sealed surface, a phase-change temperature of 303.10K, a latent heat-storage capability of 63.85 J/g and an average particle size of 9.32 μm, and that the optimal acidification time for microcapsule synthesis is 90 min.

    Spectral Properties of Water-Soluble Squarylium Indocyanine Dyes in Surfactants
    Song Bo Zhang Qian Ma Wen-hui Peng Xiao-jun
    2009, 37(9):  144-150. 
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    In order to investigate the application of fluorescent dyes in the field of bioanalytical technology,the absorption and emission spectra of four water-soluble squarylium indocyanine dyes in such surfactants as cetyltrimethy-lammonium bromide（CTAB）,sodium dodecyl sulfate（SDS） and Triton X-100（TX-100） in micelle-mimic physio-logical conditions were measured.The results show that there exist effective interactions between the dyes and the micelles in an order of CTAB〉TX-100〉SDS,that the maximum absorption and emission wavelengths of the dyes all exhibit a red shift due to the formation of micelles in surfactant solutions, that the maximum absorption wavelength exhibits a red shift of 11 - 16nm, that, with the increase of CTAB concentration which is less than the critical micelle concentration, dyes a and d form H-aggregate whereas dyes e and f form not only H-aggregate but also J-aggregate, that the aggregates disaggregates when CTAB concentration is larger than the critical micelle concentration, and that the fluorescent densities and quantum yields of the dyes significantly improve in appropriate surfactant solutions.

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