2010 volumne 31 Issue 02
WANG Zhenjun
Abstract: In view of the phenomena that mixtures of lightweight concrete were prone to be in separation in condition of high fluidity,which resulted in the bad workability of mixtures,a mended L一800 rheological testing apparatus of concrete mixtures and the testing methods of concrete mixtures workability were adopted to study influences of mineral admixtures,fly ash and silicon fume,on workability of the mixtures of high flowing lightweight concreto(HFLC),such as the value of t(40,T),which was the time when concrete mixtures flowing the length of 40 cm at the different time intervals.slump and spread values.The results indicate that the addition of the mineral admixtures is a key measure to make the mixtures have good performances and the opti—real dosage of first grade fly ash and is 30%and 2%cement mass respectively.
DONG Qiwu; WANG Ye; LIU Minshan
Abstract: Three—dimentional numerical simulation on heat transfer in fluid flowing across tube bundles iscarried out by using the computational fluid dynamics software FLUENT,while the totle tube bundles are 87 intubes staggered arrangement with the specific flowing impact angles of 45°,60°,75°and 90°.The longitudinaland transverse tube pitch is 9.5 mm and 1 1 mm,respectively.The numerical simulation results of the averageheat transfer Nusseh number and the pressure drop from the inlet to outlet of models are investigated and com—pared with)Kykayckac’S experimental correlation.With the Reynolds numbers from 5 000 to 20 000 in thispaper,the fitting formula of the average heat transfer Nusseh number is given for different impact angles.Thelocal heat transfer character in the circumferential direction along tube walls is also analyzed in detail.Itshowed that,the turbulent boundary layer separates from tube walls when the circumferential angle is about105 °,when the heat transfer coefficient is the lowest;the average heat transfer Nusseh number and pressuredrop become bigger as the flowing impact angles increase.The comprehensive heat transfer performance ismuch better when the flowing impact angle is 45°
GAO Danying; WEI Dong; ZHU Haiting; etc
Abstract: Taking five steel fiber reinforced high—strength concrete edge joints with the variable parameters ofthe fraction of steel fiber by volume(0.5%、1%、1.5%)and the ratio of stirrup(two rows of a diameter of8 ram、five rows of a diameter of 8 mm)in core zone,the hysteresis curve,displacement ductility and the work—ing index of the steel fiber reinforced high—strength concrete frame edge joint under the low cycles loading areinvestigated.The results show that the steel fiber can significantly improve the ductility and enlarge the energydissipation capacity of the high strength concrete frame joint.So the steel fiber will be conducive to anti—seismic structure and have asignificant effect on resolving the crowded conditions of the stirrups in core zone of thejoints and constructional conditions.
WANG Xinling; WANG Kun; NIU Xuejiao; etc
Abstract: In order to explore the optimization of the reinforcement scheme of post-earthquake damaged concrete structures, the composite reinforcement (JKJ-A, JKJ-B) of the two severely damaged reinforced concrete frames was carried out with angle steel and carbon fiber cloth, and the horizontal and low-cycle repeated load tests were carried out to simulate the seismic action. The test results show that with the increase of the length of the copper limb at the nodal angle, the energy dissipation capacity and bearing capacity of the composite reinforced frame are enhanced, and the composite plus back damage frame has a better bearing capacity than the damaged concrete frame reinforced with carbon fiber cloth only. With the increase of the length of the joint reinforcement angle steel limb, the seismic resistance of the reinforced frame is improved.
AI Yongming; HUANG Pingming; YANG Bingcheng
Abstract: Considering the effect of non—directional load of cables and suspenders,the principle of the mini—mum potential energy is used to analyse the instability behavior in lateral of cable—stayed arch bridge,and apractical formula to determine the critical load of lateral stability of cable-arch structure is given.The resultshows that the size of cable—plane,level inclination,the size of cable tension,and the anchor position on archof the cable structure and rise-to—span ratio,the bending stiffness of crossbar in arch tangential plane and thequantity of crossbar of arch structure have obvious effect on the lateral stability,but the effect of the bendingstiffness of crossbar in arch radial plane.the torsional stiffness and vertieal bending stiffness of arch rib iSsmall.Considering the effect of non—directional load,cable can improve the lateral stability significantly.
QIAN Xuesong,HU Zhaotong,LI Jiawu
Abstract: In this paper,ANSYS FEM program is used to study the lateral instability behavior caused by static—wind load of cable—stayed arch bridge.Furthermore,the parameters,including initial cable tension,towerheight,cable distance and position of cable on arch is considered in theoretical study.The results show thatcables can control buckling form effectively,and cable—stayed arch bridge has better performance of lateralwind—resistant stability.Initial cable tension,tower height can be increased,and cable distance can be re—duced to improve performance of lateral wind—resistant stability,and the effect of tower height is most extraordinary,increasing tower height ever doubled the performance of lateral wind—resistant stability nearly.Posi—tion of cable on arch has obvious effect on the performance of lateral wind—resistant stability,and cable—plane eenterline is appropriate in the quartile of arch rib.
YUE Jinchao,LI Xinming,YUE Xudong
Abstract: In order to study the water stability of steel slag soil and direct the construction of road bed,the va‘rying characters of unconfined compressive strength and splitting tensile strength in different soak periods anddifferent wetting and drying cycles have been carried out in the state of optimal water content under certaincompaction.The two strength indexes of steel slag soil were investigated with the different water content whensample formed.Test results showed that after different soak periods and different wetting and drying cycles,both the unconfined compressive strength and the splitting tensile strength of steel slag soil with 8%or 1 5%steel slag decreased sharply in the initial period,and drove to stability of status at last time.As more steel slagis added,the steel slag soil had better water stability.For different water contents,the influence on both the us—confined compressive strength and the splitting tensile strength of steel slag soil decreased as the period of sam—pie formed increased.The effect is the same by increasing the proportion of steel slag.
XIA Jiangtao; YANG Ping
Abstract: Based on horizontal freezing reinforcement project for a subway station,a study on the developmentof temperature field in cup—shaped frozen soil wall was carried out by site monitoring.The development char—acteristies of salt—water temperature and soil temperature in freezing zone were analyzed.And the time of fro—zen soil wall closure and the velocity of the growth were calculated during the primary freeze period.Accordingto site monitoring analysis,compared with temperature sensor of the shallower depth in the same observationhole,time of frozen soil wall closure of temperature sensor of the deeper depth was longer and its velocity wasslower in plate reinforced zone,while time of frozen soil wall closure and average velocity of the growth did notchange significantly in cylinder reinforced zone;Average velocity of the growth of frozen soil in plate reinforcedzone was faster than that of cylinder reinforced zone in the inerface between frozen soil and underground con—tinuous wall obviously.Time of frozen soil wall closure was 3 1 d and average velocity of the growth was 20.9mm/d in cylinder reinforced zone.Growth velocity displayed a marked difference in plate reinforced zone,thefast velocity was 60.5mm/d and the slowest one was 35.3mm/d.
JI Xiaoping; ZHENG Nanxiang; LI Xin
Abstract: The influence of different interlayer touch types on high—temperature of asphalt pavement was dis—cussed.The influence of different interlayer touch types on shear stress of asphalt pavement was studied withthe soft of BISAR,and the anti—shear strength of compound Marshall sample bonded with different tack coatswas tested with the method of direct shear test.At last,the DS and total deformation of compound rutting sam—pie was tested by the rutting test.The results showed that:the shear stress of asphalt surface increased sub—stantially when the interlayer touch type was smooth,and as aresult,the rutting was easier to oceurred;thetack coat improved the anti—shear strength of interlayer and different materials had different effect;the interlayer touch with high anti—shear strength would help to improve the high—temperature of compound sample;it is meaningful to take appropriate measures to improve the interlayer touch condition for improving high tern—perature performance of asphalt pavement.
WU Xuemei; LI Yuan; GUAN Zongfu
Abstract: This paper is focused on preparing concrete by crushing the ceramic wastes to make the recycledaggregate to substitute for the natural aggregate in different ratios(50%、80%、100%).The comparison of themechanical performances between recycled ceramic concrete and normal concrete is conducted,as well as theinterfacial zone between recycled aggregate and masonry mortar.Results show that the mechanical performances of recycled ceramic concrete decrease no more than 1 5%in comparison with that of natural concretethough the performances exhibit monotonically decreasing as the recycled ceramic aggregate ratio increases,andthe bonding performance of interfacial zone is better.Therefore,the recycled ceramic aggregate can fully substitute for the natural aggregate to prepare concrete.
ZHANG Bei; LI Hailong; GUO Chengchao; etc
Abstract: The usage limit of road decreases with the appearance of asphalt pavement early crack.In order tostudy the propagation behavior of asphalt pavement surface crack in use,the change law of the stress intensityfactor Kll of surface crack was analyzed under moving load with the commerce FEM software ABAQUS basedon fracture mechanics theory.The response of asphalt pavement with surface crack was studied under the con.dition of different crack depth and different frictional contact status between layers.The effects of pavementparameters such as surface thickness and surface modulus and base modulus on the crack propagation were dis—cussed.Some theoretical reference was provided for the rational design of semi—-rigid asphalt pavement andfor the maintenance and rehabilitation of asphalt pavement.
YAN Weihong; MENG Fenglin; DONG Zhonghong
Abstract: To study the premature disruption of the semi—rigid base asphalt pavement,a multi—layer viscoe·lastic dynamic model where the vehicle load is handled as moving load was used to analysis the dynamic re—sponse of the typical semi—rigid base asphalt pavement,and the influences of the axle load,the vehicle speedand the tire pressure on the shearing strain at the bottom of the AC layer and the shearing strain distribution inthe AC layer were studied.It showed that the shearing strains increase with the increase of the axle load andthe tire pressure,and increase with the decrease of the vehicle speed.Especially,when the axle load is rathersmall,the destory of the vehicle exerting on the pavement is mainly took place at the wearing surface layer andthe middle surface layer,while when the axle load is rather big,the destory is mainly set at the middle Surfacelayer and the low surface layer.The tire pressure has a notable influence on the shearing strain at the depthrange from 2cm to 8cm.With the increase of the tire pressure,the depth where the maximum shearing strainoccures becomes shallower.
SHI Gang; GAO Guangyun; GUO Yuancheng
Abstract: The transient response of saturated layered ground subjected to concentrated loads is investigated.By using Laplace transform,Fourier series expansion and Hankel transform,the Biot’8 dynamic equations ineach layer are reduced into a series of ordinary differential equations,which can be solved by thin layeredmethod(TLM).The general solutions for displacement and pore pressure in Laplace domain are derived byanalytical inversion of Hankel transform,and the solutions in time domain are obtained by numerical inverisonof Laplace transform.Finally,some examples are given to validate the method.
LOU Ping; ZHAO Yongchao
Abstract: Vehicle and track are considered as an entire system.The vertical equations of motion for a vehicle——track system are formulated by the principle of total potential energy with stationary value in elastic systemdynamics and the“set—in right—position”rule for formulating matrices.The random irregularity of the rail isconsidered.The dynamic response of train at five different speed levels excited by the irregularity of track areobtained.The maximum dynamic response of each speed is considered asample observations of the randomvariable.The samples are regarded as random variable which is used in the probability analysis.The resultsindicate that the random variables of the maximum displacement and acceleration of rails and track slabs,themaximum wheel acceleration,and the maximum wheel—rail force all fall into normal distribution.With theincrease of train speed,the mean of random variable maximum value of wheel—rail force and the mean of ran·dom variables maximum value of the track dynamic response also increased.
CUI Xiulong; WU Xiaoping; LI Hongwang
Abstract: This paper introduced the technology of ArcEngine component and the application framework onplug—in GIS,and made the secondary development mainly based on the technology of GIS(Geographic Infor—mation System).The system maked full use of buffer analysis,overlapping analysis and spatial relationship a—nalysis of GIS,the high—speed railway ecological restoration management system on GIS was established andsupported by model base subsystem and database subsystem.This paper also used this system to conduct thefirstly and secondly grade comprehensive evaluation of eco——environmental impact assessment and the resultsprovided a basis for optimization of railway line and ecological restoration.
WANG Dingbiao; WANG Fangfang; Zhou Junjie
Abstract: Considering the shortages of current used tube in the evaporative condenser such as circular tube,O—val tube and bullet tube,the paper designed a new kind of tube type called special—shaped fiat tube withgood performance.By using the FLUENT software,a numerical simulation research on the forced convectionair flow of 4 kinds of tube bundles which were circular tube,oval tube,bullet tube and special shaped fiattube WaS conducted.The mathematical model of the tube bundle flow field was established.Our implementa—tion incorporated a SIMPLE—based semi—implicit solution algorithm that was applied to iterating calculation.Inlet velocity from 1.5 to 3.9 m/s was calculated separately.The data of simulation was processed by Tecplot10,which provided a direct illustration of the velocity,pressure and temperature fields of the flowing air in thetube bundles.The relationship curve of the pressure changing with the air velocity was also presented.The re—suh demonstrated that comparing with the other 3 tube types,the average pressure drop of the new tube typewas 30%.21%and 15%smaller and the average air temperature in the outlet cross section was higher.
ZHAO Wenen; ZHANG Xiaoge; HU Shuitao; etc
Abstract: The oxidized acorn starch was prepared by using hydrogen peroxide as the oxidant agent and Cu(II)ions as the catalyst.The effects of pH,oxidant agent dosage,catalyst dosage,reaction temperature,andreaction time of the oxidation reaction were examined on the carboxyl percentage and the carbonyl percentageof the oxidized starch.The results showed that the oxidized acorn starch with 0.9140%carboxyl percentage U·sing 0.0524%of the catalyst dosage and with 0.9183%carboxyl percentage using 0.1244%of the catalystdosage,respectively,was obtained under such conditions of reaction as temperature being 45。C,time 3 h,pH=8,and 20%of hydrogen peroxide.
ZHAN Yuzhong; ZHOU Xiang; HU Bin; etc
Abstract: The hydrothermal synthesis of copper hydroxyphosphate is studied by uniform design method.Theproduct synthesed was characterized by XRD,SEM,FTIR and TG—DTA。The optimal synthesis ratio is ethyl·enediamine/phosphoric acid/copper acetate/water(molar ratio)=1/9.5/7.25/399.Under the optimal con—dition,the pure phase of copper hydroxyphosphate can be synthesed reliably.The synthesis time is short andthe crystal size of product is uniform in the case of ultrasonic pretretament for the mixture of raw materials.Thecopper hydroxyphosphate synthesed has very high activity for the catalytic degradation of p-nitrophen01.
ZHANG Congliang; LI Baoying; WANG Yan
Abstract: The equilibrium adsorption capacity of modified fly ash was determined by equilibrium method and correlated with Freundlich model, and the model parameters and thermodynamic parameters such as △G, △H and △S were calculated. The results showed that the specific surface area of modified fly ash was 3.24 times that of the modified fly ash before modification. The experimental data can better follow the Freundlich model; The adsorption of norfloxacin in water by modified fly ash is a spontaneous, exothermic entropy reduction process.
FAN Zhonglei; WANG Linghui; SHEN Jinge
Abstract: The ethylenediamine—grafted silica gel(EDA/Si02)was prepared by CPTCS as surface anchorand ethylenediamine as surface modification agent.The effects of temperature,time and ethylenediamine con—centration on the substitution reaction of ethylenediamine with CPTCS—SiO,were investigated in detail.Andit was obtained that the optimal conditions were reaction temperature 333 K,reaction time 16h,and n(ethyl.enediamine):n(chlorine on the SUrface of CPTCS—Si02)more than 9.The substitution reaction kinetics ofethylenediamine with CPTCS—Si02 was also investigated. It was obtained that the parameters of the apparentkinetic model were reaction order 4.37.activation energy 55.44KJ/mol and frequency factor 5.06×10 7h一1by the kinetics data fitted with the differentiation and minimum variance linear regression.Infrared spectrosco—PY and its performance show that ethylenediamine was grafied on silica gel by substitution reaction.
JIANG Bingyan; CHEN Wen; YUAN Li; etc
Abstract: With the finite elements model based on system dynamical theory and with the help of ANSYS/LS-DYNA,the research simulates the in-mold dynamics for microfluidic chips.Based on the results of thesimulation,the research shows that:the maximum Von raises stress is below the materials summit limits;thekey points displacements have certain impact on the alignment precision of the mold cavities.The researchprovides the theory for the in—mold assemble(IMA)technology.
WANG Zhongyong; FENG Weina
Abstract: A new combined estimation method of parameter and state for nonlinear systems based on particlefilter is proposed.The algorithm uses particle filter methods,combined with the kernel smoothing contractionmethod,replaces the traditional use of the Gaussian distribution with the standard beta distribution to fit theposteriori distribution of the unknown parameter of the system,in order to achieve the iteration of the parame—ter estimation of the nonlinear system.Simulation experiment results show that the algorithm improves the esti-mation accuracy of the the state and the unknown parameter,and the convergence of the estimation has alsobeen significantly improved.
FAN Wenbing; LI Jianhua; Yu Shipeng; etc
Abstract: This paper analyzes the principle and characteristic of CRC calculations in UHF RFID system datacommunications based on the ISO/IEC 18000-6 standard.Using abyte—wise method for parallel computingCRC and the Verilog HDL language,and taking CRC-CCITT generator polynomial for example,We designedabyte-oriented parallel CRC-1 6 circuit based on the classical LFSR circuit.Timing simulation in Quartus II8.0 integrated development environment,and verifying it in the FPGA chip EPl C6Q24017,the results showthat this circuit we designed can processing 8 bit data per clock cycle.It is in agreement with the ISO/IEC1 8000—-6 standard and meet the requirements of communication rate in UHF RFID systems.
SHAO Xia; ZHANG Dehui; ZHANG Weidang
Abstract: The ber distributions,which can give a detailed description about the error correcting ability of e卜ror control codes,are introduced in this paper to analyze the interleavers of 3 GPP interleaver.block interlea—ver and random interleaver.The ber distributions are given under different puncturing patterns.The resultsshow that the ber distribution of block interleaver is periodic apparently and that of the random interleaver isspread more randomly.As for the 3 GPP interleaver,because of its combination construction,its bet distribu.tion has the advantages of both block and random interleavers。i.e.it has more flat distribution and lower av-eraged ber.
WANG Jie; WANG Xiaochange
Abstract: Aiming at rolling bearings,the implementation procedure of a new style fault diagnostic system ispresented in this paper.The combination of rough sets and BP neural network are adopted in the design of thediagnostic system.Utilizing the knowledge reduction ability of rough sets theory,the diagnostic system prepro—cesses the collected fault symptom data at first,i.e.the discretization of continuous attributes by using compe—tition learning neural networks.The intermediate output is introduced to software of“Rosetta”to be analyzedstep by step until the smallest condition attributed sets are obtained。Based on the smallest condition attributedsets,the BP networks are built,which are used to recognize the faults of rolling bearings and then transfer thefault states back to LabView for displaying.The example analysis indicated that the system can enhance faultdiagnosis convergence speed and the network training time reduces 1 76 steps at the same expected error.
LU Ling; SUN Xinde
Abstract: A new blind detection digital watermarking algorithm based on Logistic mapping is proposed in thispaper,which can be more effective for digital media copyright protection.At first watermarking image is encrypted by the chaotic sequence generated by Logistic mapping.According to the human visual system(HVS)some small blocks with size 8宰8 that have more texture complexity will be chosen.In each chosen sub—block some DCT coefficients are selected effectively in accordance with the property of common digital signalprocessing.Each pair of adjacent DCT coefficients can carry one bit watermarking information.Simulation ex—periments show that the algorithm improves effectively the robustness and the systems security.
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