2010 volumne 31卷 Issue 02
WANG Zhenjun.

Abstract:
Aiming at the phenomenon that light concrete mix is easy to stratify under the condition of high fluidity, resulting in poor workability, the effects of L-800 concrete mix flow performance tester combined with concrete mix performance determination method were used to study the effects of fly ash and silica ash and other mineral admixtures on the flow time t(40.T), slump and expansion of large fluidity light concrete (HFLC) mixture flowing over a distance of 40 cm at different time intervals. The results show that the addition of mineral admixtures is the key factor to ensure the good performance of the HFLC mixture, and the optimal content of grade I fly ash and silica ash is 30% and 2% of the total cement dosage, respectively.

Dong Qiwu; WANG Ye; Liu Minshan

Abstract:
Using the computational fluid dynamics software FLUENT, the heat transfer under the flow impact angle of 45°, 60°, 75° and 90°, and the fluid flows around 6 rows and 87 staggered tube bundles is simulated in 9D. The longitudinal and transverse tube spacings of the tube bundle were 5.11 mm and 5 mm, respectively.The average heat transfer Nussel number and model inlet and outlet pressure drop of the tube bundle were investigated, and compared with the experimental correlation formula of Rukauskas, when the Reynolds number was 000 20~000 4, the fitting formula of Nussel number of the tube bundle under the flow impact angle was given, and the local heat transfer characteristics of the tube circumference were meso-analyzed. The results show that the turbulent boundary layer is separated from the pipe wall when the circumferential angle is about 105°, and the heat transfer is the worst. The larger the flow impact angle, the greater the average heat exchange Nussel number of the tube bundle and the pressure drop at the inlet and outlet of the model. When the flow impact angle is 45°, the comprehensive heat transfer performance is better.

GAO Danying; WEI Dong; ZHU Haiting; etc

Abstract:
Taking five steel fiber high-strength concrete side node specimens as the research object, the hysteresis curve, displacement ductility and power ratio index of steel fiber high-strength concrete frame edge joints under low cycle repeated loading were studied by taking the steel fiber volume ratio (5.0%, 5%, 1.1%) and steel bar stirrup ratio ratio (5 rows φ2 and 8 rows φ5) as the changing factors. The results show that the incorporation of steel fiber can significantly improve the ductility of high-strength concrete frame joints, improve the energy dissipation capacity of frame joints, and be conducive to structural seismic resistance, which has a significant effect on solving the stirrup density and improving the construction conditions in the node area.

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 non-conservatory force effect of cable and suspension bridge, the energy method is used to analyze the lateral stability problem of the downward bearing parallel double-ribbed oblique tension arch bridge, and the practical calculation expression of the transverse buckling critical load of the oblique tension arch bridge is obtained. The results show that the cable surface size, horizontal inclination angle, cable tension, anchoring position on the arch, the sagittal span ratio of the arch structure, the bending stiffness of the cross brace in the tangential surface of the arch, the number of cross braces and other factors have a great influence on the lateral stability performance of the structure, while the bending stiffness of the cross brace in the radial surface of the arch, the torsional stiffness of the arch ribs, and the vertical bending stiffness have little influence. After considering the non-conservatory force effect, the lateral stability performance of the structure is significantly improved by the cable.

Qian Xuesong; Hu Zhaotong; Li Jiawu

Abstract:
The finite element software ANSYS was used to study the out-of-plane stability of cable-stayed arch bridges under static wind loading, and the influence of cables on the lateral static wind stability of cable-stayed arch bridges was considered by considering different parameters such as cable pretension, cable tower height, cable distance and cable arrangement position. The results show that the cable can effectively control the out-of-plane instability of the structure, and the cable-stayed arch bridge has high transverse wind stability. Increasing the cable pretension, increasing the height of the cable tower and reducing the cable distance can improve the lateral static wind stability performance of the structure, and the tower height has the most significant impact, and the height of the cable tower can even nearly double the lateral static wind stability performance. The arrangement position of the cable has a significant influence on the stability of the transverse static wind, and the centerline of the cable surface should be located at the quarter of the arch rib.

Lejin Dynasty; LI Xinming; Le Xu Dong

Abstract:
According to the construction needs of subgrade engineering, the variation law of unconfined compressive strength and splitting strength of two different steel slag stabilizing soils under different water saturation times and different times of water loss and water absorption dry and wet cycles was studied, and the sensitivity of steel slag stabilized soil to forming moisture content was discussed near the optimal moisture content. The test results show that the steel slag stabilized soil with a steel slag content of 8% and 15% is in the water saturation test and the dry and wet cycle test. The compressive strength and splitting strength of steel slag stabilized soil decreased sharply in the early stage, and eventually tended to stable values, and the water stability was improved with the increase of steel slag content. With the increase of age, the influence of steel slag stabilized soil strength gradually decreases when the forming moisture content changes, and increasing the steel slag content can also effectively reduce the influence of forming moisture content change on its strength.

Xia Jiangtao; Yang Ping

Abstract:
Relying on the horizontal freezing reinforcement project of shield tunnels in a subway station, the development characteristics of brine temperature and soil temperature in different areas of the frozen zone were analyzed by real-time monitoring of the cup-shaped frozen soil wall temperature field, and the intersection time and development speed of the frozen soil wall in different areas of the frozen area were calculated. The analysis of monitoring results showed that compared with the measurement point with a deeper buried depth in the same temperature measuring hole, the frozen soil intersection time and development rate in the plate plus solid area were longer, and the development rate was slower, while the change of frozen soil intersection time and development speed in the cylinder reinforcement area was not obvious. At the interface between frozen soil and underground continuous wall, the average development rate of frozen soil in the plate reinforcement area was significantly faster than that in the cylindrical reinforcement area, and the intersection time of the frozen soil wall in the cylindrical reinforcement area was 31 d, and the average development rate was 20.9 mm/d, while the average development rate of frozen soil wall in different areas of plate reinforcement area was obvious, the fastest development rate was 60.5 mm/d, and the slowest development rate was 35.3 mm/d.

JI Xiaoping; ZHENG Nanxiang; Li Xin

Abstract:
The shear stress of asphalt surface layer under different interlayer contact conditions was calculated by BISAR software, the shear strength of composite Marshall specimens with different adhesive layers was determined by direct shear test, and the Ds and total deformation of composite rutted plates were determined by rutting test. The results show that the completely smooth interlayer contact conditions greatly increase the maximum shear stress of the asphalt surface layer, and accelerate the shear failure of the asphalt surface layer and the occurrence of ruts. The adhesive layer improves the shear strength between layers, and different adhesive layer materials have different effects on the improvement of interlayer contact conditions. The interlaminar contact with high shear strength can improve the high temperature performance of the composite rutted plate.

Wu Xuemei; Li Wish; Guan Zongfu

Abstract:
Waste ceramics are crushed and screened into recycled aggregates, and concrete is prepared by replacing the corresponding natural aggregates in different proportions (50%, 80%, 100%). On the basis of the comparative study of the mechanical properties of waste ceramic recycled aggregate concrete and natural aggregate concrete, the bonding properties of recycled aggregate and cement stone are further comparatively studied. The results show that although the mechanical properties of concrete decrease with the increase of the amount of recycled aggregate, the decrease rate is mostly not more than 15%, and it shows good interfacial bonding performance, so waste ceramic recycled aggregate can completely replace natural aggregate for the preparation of concrete.

ZHANG Bei; LI Hailong; GUO Chengchao; etc

Abstract:
The appearance of early cracks in asphalt pavement reduces the service life of the road. In order to study the crack propagation behavior of asphalt pavement surface under use, based on the fracture mechanics theory, the change law of crack stress strength factor K11 under moving load was analyzed by using the finite element software ABAQUS, the pavement response under different crack cracking depths and different interlayer frictional contact conditions was studied, and the influence of pavement structural parameters such as surface thickness, surface layer and base modulus on crack propagation was discussed. It provides a theoretical reference for the rational design of semi-rigid base asphalt pavement and the maintenance and maintenance of asphalt pavement.

Yan Weihong; Meng Fenglin; Dong Zhonghong

Abstract:
In order to study the early failure phenomenon of semi-rigid base asphalt pavement, the dynamic response of typical pavement structure was analyzed by using the dynamic model of viscoelastic layered system under moving load, and the effects of axle load, velocity and tire pressure on the shear strain at the bottom of the surface layer and the internal shear strain distribution of the surface layer were studied. The results show that with the increase of axle load and tire pressure, when the speed decreases, the internal shear strain of the surface layer and the shear strain of the bottom layer of the surface layer increase. When the axle load is small, the damage caused by the vehicle on the road surface mainly occurs in the upper and middle surface layers, while when the axle load is large, the damage mainly occurs in the middle and lower layers: the change of tire pressure has a serious impact on the shear strain in the depth range of 2-8 em, and with the increase of tire pressure, the depth position of the maximum shear strain decreases.

Shi Gang; Gao Guangyun; Guo Yuancheng

Abstract:
Based on the Biot saturated porous medium theory, the Laplace transform, Fourier series expansion and Hankel transform are applied to transform the wave equation into a set of second-order ordinary differential equations. The principle of thin layer method is used to solve the discrete solution in the vertical direction, and the Laplace solution of the Lamb problem of saturated layered foundation is obtained, and the numerical solution in the time domain is finally obtained by using the Laplace numerical inverse transformation.

Lou Ping; Zhao Yongchao

Abstract:
Considering the vehicle and track as a system, the vertical vibration equation of the system is established by using the principle of constant value of the total potential energy of the elastic system dynamics and the "seating" law of the matrix, considering the random unevenness of the track, and obtaining the random dynamic response of the track at five running speeds. The maximum value of the track dynamic response obtained each time at each speed of the train is regarded as an observation of a random variable. The calculation results show that the random variables such as the maximum displacement, acceleration, wheel acceleration and wheel-rail force of the rail and track plate at each speed of the train follow the normal distribution. As the speed of the train increases, the mean of the random variable of the maximum value of the wheel-rail force and the mean of the random variable of the maximum value of the track dynamic response also increase.

Cui Xiulong; WU Xiaoping; Li Hongwang

Abstract:
With geographic information system (GIS) as the main technical support, ArcEngine component technology is introduced, secondary development is carried out based on plug-in GlS application framework, and with the support of system model library subsystem and database subsystem, the buffer analysis, intersection analysis and spatial relationship analysis functions of GIS are fully utilized to establish a high-speed railway ecological restoration management system, and use the system to conduct first-level comprehensive evaluation and second-level comprehensive evaluation of the ecological environmental impact of high-speed railway. According to the evaluation results, it provides a basis for the optimization of routes and ecological restoration management.

Wang Dingping; Wanfangfang; Zhou Junjie

Abstract:
In order to verify its excellent performance, the forced convection air in the four tube bundles was numerically simulated by FLUENT software, and the mathematical model of the tube beam flow field was established, and the semi-implicit method (SIMPLE) for solving the pressure coupling equation system was used to iteratively calculate and solve, and the inlet flow rate was calculated in the range of 4.1~5.3 m/s. Tecplot9 post-processing software was used to visually characterize the velocity field, temperature field and pressure field of air, and the relationship curve of pressure drop loss with air flow rate was given. The numerical simulation results show that compared with the other three tube types, the pressure drop of the new special-shaped flat pipe is reduced by about 10%, 3% and 30%, and the average temperature of the air in the outlet section is increased.

Zhao Wenen; ZHANG Xiaoge; HU Shuitao; etc

Abstract:
Acorn oxidized starch was prepared by using hydrogen peroxide as oxidant and Cu2+ as catalyst, and the effects of pH value, oxidant dosage, catalyst dosage, reaction temperature and reaction time on the carbonyl and carboxyl mass fractions of acorn oxidized starch were investigated. The results showed that the optimal reaction conditions were: reaction temperature 45 °C, reaction time 3 h, pH=8, H2O2 dosage was 20% (relative to starch dry weight, the same below), under this condition, when the catalyst dosage was 0.052 4% (relative to starch dry weight mass), acorn oxidized starch with carboxyl mass fraction of 0.914 0% was prepared. When the catalyst dosage was 0.124 4%, an acorn oxide starch with a carbonyl mass fraction of 0.918 3% was prepared.

Zhan Yuzhong; ZHOU Xiang; HU Bin; etc

Abstract:
The synthesis of copper hydroxyphosphate by hydrothermal method was studied by uniform experimental design, and the synthesized copper hydroxyphosphate was characterized by powder X-ray diffraction analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, and differential thermal-thermogravimetric analysis. The optimized synthesis ratio is: n(ethylenediamine): n(phosphoric acid): n(copper acetate): n(water)=1.0:9.5:7.25:399, under which the pure phase of copper hydroxyphosphate can be stably synthesized. The ultrasonic pretreatment raw material mixture can shorten the synthesis time, the particle size of the product is more uniform, and the synthesized copper hydroxyphosphate has high catalytic degradation of p-nitrophenol.

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 Jin Pigeon

Abstract:
Ethylenediamine-grafted silica gel material was synthesized by using chloropropyltrichlorosilane as bridging agent and ethylenediamine as silica gel surface modifier. The effects of reaction temperature, reaction time and ethylenediamine content on the substitution reaction were investigated, and the optimized reaction conditions were: reaction temperature 333 K, reaction time 16 h, molar ratio of ethylenediamine to chlorine content on the surface of CPTCS-SiO_2 was greater than 9. The frequency factor was 4.37×55~44h~(-5), and the grafting reaction of ethylenediamine on the surface of silica gel was verified by infrared spectroscopy and performance determination.

Jiang Bingyan; CHEN Wen; Yuan Li; etc

Abstract:
Based on the system dynamics theory of finite element method, explicit ANSYS/LS-DYNA finite element analysis software was used to simulate and calculate the in-mold motion elements of microfluidic chip in-mold bonding mold, and the calculation results were analyzed. Based on the calculation results, the structure of the mold is improved, its structure is optimized, and the force condition is improved. The results show that the maximum stress value of the in-mold element is within the yield limit of each component material. The displacement of the key junction has a certain influence on the alignment accuracy of the cavity. The research results provide a theoretical basis for the structural design and development of in-mold assembly mold (IMA), and provide a theory for in-depth study of the relationship between mold core braking and mold fatigue life and improve mold life.

Wang Zhongyong; Feng Weina

Abstract:
A new joint estimation method of nonlinear system parameters and states based on particle filtering is proposed. The algorithm uses the particle filter method, combined with kernel smooth contraction technology, and uses the standard beta distribution instead of the traditional Gaussian distribution to fit the posterior distribution of unknown parameters of the system, and finally realize the iterative estimation of parameters in the nonlinear system.

FAN Wenbing; LI Jianhua; Yu Shipeng; etc

Abstract:
The principle and characteristics of cyclic redundancy check (CRC) algorithm in data transmission of ultra-high frequency (UHF) RFID system based on ISO/IEC 18000-6 protocol are analyzed, and on the basis of the classical LFSR circuit, the method of parallel calculation of CRC check code by byte is adopted, and the 8-bit parallel CRC-16 circuit is designed and implemented by Verilog HDL language by taking the CRC-CCITT generation polynomial as an example. In the Quanus II.8.0 comprehensive development environment, the timing simulation is carried out, and the test and verification are carried out on the FPGA chip EP1C6Q24017, and the results show that the designed circuit processes 8-bit data in one clock cycle, which meets the protocol requirements and meets the communication rate requirements of UHF RFID system.

Shao Xia; ZHANG Dehui; Zhang Wei Dang

Abstract:
Since the error rate distribution can more deeply and meticulously describe the praseodymium correction ability of error correction code, the performance of 3GPP interleaver, group interleaver and random interleaver in Turbo code at different bit rates is compared and analyzed by using the method of error rate distribution. The simulation results show that the error rate distribution of the group interleaver has obvious periodic characteristics. The random bit error rate distribution of random interleavers is more obvious, and the bit error rate distribution is more extensive than that of group interleavers. For the 3GPP interleaver, its bit error rate distribution has a relatively flat distribution curve and a lower average bit error rate.

WANG Jie; Wang Xiaochange

Abstract:
For rolling bearings, a new type of fault diagnosis virtual system combining rough set theory and neural network technology is realized. The system uses the knowledge reduction ability of rough set to preprocess the collected fault symptom data, that is, the competitive learning neural network is used to discretize the continuous attributes, and the results are gradually analyzed and processed into Rosetta software to obtain the minimum conditional attribute set, on this basis, the BP neural network is constructed for fault identification, and the network output is sent back to LabView for display. Case analysis shows that the system can improve the convergence speed of rolling bearing fault diagnosis, and the network training time is reduced by 176 steps under the same expected error.

Lu Ling; Sun Xinde

Abstract:
A new robust blind detection digital watermarking algorithm based on Logi8tic encryption is proposed. The chaotic sequence generated by the logistic mapping feature is used to generate the watermark sequence. Combined with the visual system (HVS) of the human eye, subblocks in the original image are selected; On each selected subblock, DCT coefficients are selected according to robustness requirements; The watermark is embedded by comparing the size of adjacent coefficient pairs. Experimental results show that the proposed algorithm has the characteristics of strong robustness, high security, good transparency, and blind extraction, and can be effectively used for copyright protection of digital media.

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