Abstract:Taking network cost and nodal reliability as optimization object and restriction, a network topology optimization model is presented for the aim to achieve the best topologies of lifeline networks under earthquake. In order to speed up the optimization process, the element investment importance is introduced based on recursive decomposition algorithm. As this model is a typical combinatorial optimization problem, three approaches, genetic algorithm (GA), simulated annealing algorithm (SAA) and simulated annealing genetic algorithm (SAGA), are used to solve it. When GA is used, a generation including many genes is initially created with each gene representing a network. Then by using selection, crossover and mutation operators, a new generation is evolved. After a number of iterations or when some criteria are met, a near-global optimal solution could usually be found. SAA takes a network topology as its current solution and produce a new solution by perturbing. If the perturbation result is an improved solution, it is accepted and the current solution is updated accordingly. Otherwise, it can also be accepted at a probability. The perturbations and updates repeat until some criteria are met. Replacing the mutation operator in GA with perturbations and updates in SAA, SAGA is established to solve the optimization model. Moreover, two example networks are evaluated to compare the efficiency of these algorithms. The results indicate that SAA performs best.

Abstract:The stiffness of middle tower and the anti-slip stability between cable and saddle on the top of middle tower are the key issues of designing multi-span suspension bridges.The critical span for the anti-slip stability on the rigid and flexible middle tower is established through theoretical analysis.Then, a comparative study on the anti-slip capacity of the bridges with box girder and truss grider is conducted. Finally, the principle of choosing anti-slip factor is discussed.The results indicate that anti-slip factor is mainly related to the ratio of dead to live load and the length of span.And it is larger with increase of the span.When the critical span is reached,the anti-slip requirement on the rigid middle tower is satisfied automatically.The critical span of flexible middle tower decreases approximately linearly with increase of the displacement of tower.

Abstract:Beam bridges in the operation bear both moment effect and shear effect at the same time, and their moment and shear resistances also affect each other. The assessment of existing Beam bridges needs to consider moment-shear coupling effect. The resistance and effect variables were expanded from unary random variables into binary random variables in the paper. Based on the modified compression field theory (MCFT) adopted in AASHTO LRFD design specification, the probability models of moment-shear coupling resistance and effect were established. A new reliability assessment method was proposed to consider moment-shear coupling effect. The example analysis shows that: for the cross-section bearing both larger moment and shear effect component, the failure mechanism is the moment-shear coupling failure, the traditional method results in unsafe conclusion, and it is necessary to consider the moment-shear coupling effect during reliability assessment.

Abstract:Pseudo-static experiments on seismic behavior of 16 eccentrically constant-compressed steel box columns under cyclic lateral loading are conducted. The effects of axial compression ratio, width-to-thickness ratio of web plate and bending moment on the seismic behavior of steel box columns are investigated. The experimental results show that the buckling mode of box web plates is influenced by the loading eccentricity of axial compression outside the web plane. If the eccentricity is less than b/8 (b is the flange width), the buckling mode of the box web plates is deformed as a half sine-wave, in which the web plates deform outwards from the box and the flanges inwards, and the buckling deformation is almost symmetrical. The plastic deformation of the columns under cyclic load occurs mainly in the fixed end of specimen, and the greatest plastic deformation is generally found at 0.4h or 0.5h away from the fixed end, where h is the width of the web plate. It is also found from the experiments that the width-to-thickness ratio of web plate has the most significant effect on the seismic behavior of the steel box columns. The larger the width-to-thickness ratio is, the less plumpy the hysteresis curve becomes, the faster the skeleton curve declines, and the more severely the load-bearing capacity and stiffness of the column degenerates. The axial compression ratio has more significant effect on the seismic behavior of columns, while the effect of bending moment at the loading joint of the column is little and negligible. Based on the experimental results, a practical criterion to evaluate the applicable seismic grade of steel members and some design suggestions of width-to-thickness ratio of box-section steel column in large span structures are proposed.

Abstract:Electrochemical properties of carbonated concrete after realkalization were studied with electrochemical impedance spectroscopy (EIS) and polarization curves. The parameters of realkalisation are current density, 3A/m2 and 5A/m2, realkalisation time, 14days and 28days, the concentration of sodium carbonate solution, 1mol/L. The group of carbonated samples is 8. The first group is realkalisated, other seven groups were realkalisated every 1、2、3、8、9、10、13month. All samples are in the indoors. The electrochemical impedance spectroscopy (EIS), open circuit potential (OCP) and corrosion current were measured after the realkalisation experiment. The test result shows that the hydrogen generating at the cathode rebar during the experiment delay the re-passivation of rebar; Under the experiment conditions, the electrochemical properties of carbonated concrete after realkalization decay; From 10 months and 13 months after the realklaisation, the electrochemical properties are steady.

Abstract:The performance of different types of portal frame walls was studied using a finite element model that was verified with results from tests of four full-size portal frame walls. Parameters such as wall height, metal strip types and locations, bottom plates, sheathing and nailing pattern were investigated. Results indicate that for all the wall types, the lateral load capacities and stiffness are greatly reduced with the increase of wall height. Among the different metal strip types and locations, the tensile strength of metal strips has the greatest impact on the lateral load capacities and stiffness of portal frame walls. The walls with metal strips installed placed directly on framing members outperformed the walls with metal strips placed over the sheathing. For walls with double bottom plates and two rows of nails fastened to the bottom plate, the stiffness and lateral load capacities are slightly increased compared to the walls with single bottom plate. For walls with sheathings joined at the middle of wall height and unblocked, the lateral load capacities are the same as the walls with continuous sheathings running from the bottom to the top of the walls. The stiffness is slightly lower. The two rows of nails along end studs do not affect the lateral load capacity of the portal frame walls. However, they do increase the stiffness of the walls.

Abstract:The dowel-type connection with slotted-in multiple steel plates widely used in modern timber constructions is one of the most efficient connections for heavy timber structures. To understand the mechanical properties of the components with this type of connections well, two glulam timber beams connected with three slotted-in steel plates dowel connections were tested, one beam with connection on the pure bending zone and the other beam with connection on bending and shearing zone. The mechanical properties, failure modes and the effect of the connection location on the mechanical properties of the beams were studied. And the estimating formulas of ultimate load-carrying capacity and mid-span deflection were presented based on the test results. The tests show that the load-carrying capacity of the glulam beam with connection on the bending and shearing zone is greater than that of the beam with connection on the pure bending zone. The estimating results agree well with the test results.

Abstract:For analysis of laterally loaded piles in clay, the p-y curve method was widely used. Most p-y curve models were based on field tests, and were considered to be more realistic. Summary of commonly used experimented p-y curve models indicated that the form of measured p-y curves was complex and actual p-y curves were hardly founded out exactly. Elastic-plastic model was a simple model, which can predicted deformation behavior and load distribution of the lateral loaded piles in clay accurately by choosing appropriate parameters. After the calculation of the examples, the elastic-plastic method was proved to be simple, definite and universal, so it could be widely used instead the complex measured p-y curves in engineering.

Abstract:Macro and micro researches on pile tip penetration burried in different depth of bearing layer in pure sand is carried out under self-designed visual model test by the means of high-resolution digital imaging devices, the digital microscope visualization and image analysis procedures. The 3D non-circle particle PFC3D numerical simulation method is developed to mainly research the process of pile tip penetration in laboratary model tests in pure sand.The macro and micro variation of soil parameters is connected with the macro mechanical response in order to reveal the mechanism of soil variation aroud pile tip in the course of penetration. It mainly represents that pile tip resistance is closely related to the particle contact force around pile tip in micro side: the compacted area of particles at the bottom of the pile tip,the changing tendency of porosity and coordination number nearby the pile foot mainly decide the possibility of pile tip resistance’s change in correspond to the buried depths;when the ultimate pile tip resistance is reached, the slightly increase of capacity is caused by reinforcing effect induced by pile tip resistance to frictional resistance of pile surface side,which presented as the decreasing of porosity and increasing of contact force of particles around pile surface side in bearing layer in micro level.

Abstract:Assuming the Prandtl soil slip failure models and considering the confined water, the upper-bound limit analysis theory is used to establish the analysis method of the basal stability against upheaval and checking formula. With the proposed formulas, the effect of the confined water head, the thickness of the impermeable soil layer and the depth of the retaining wall on the stability coefficient are discussed. Calculation results indicate that it is necessary to consider the effect of the confined water on the stability against upheaval of deep excavation; and the safety factor would be smaller with the increase of the confined water head. The comparison demonstrates the applicability of the method used in this paper. The results provide a reasonable calculation method for the design of foundation pit subjected to confined water in soft clay.

Abstract:The compacted clay liner (CCL), the main anti-seepage facilities in landfill and generally made up of clayey soil, will adsorb the contaminants of the leachate when it prevent the leachate from polluting the groundwater and surrounding soils. The permeability of the CCL is affected by its microscopic pore structure changes due to the adsorption of clay. It is assumed that the adsorption of contaminants on the CCL is in accordance with the linear model, the pore distribution in the CCL is uniform and it is only affected by the adsorption. Based on the conservation of volume and mass, an empirical formula was presented for CCL to evaluate the changes of porosity induced by the adsorption. Meanwhile, a new unsaturated permeability model was also suggested considering the adsorption effects of contaminants on the CCL pore structure. Finally, the effects of adsorption of CCL on its unsaturated permeability were analyzed by numerical calculation. The results show that the adsorption of contaminants on CCL can reduce the porosity and improve the performance of seepage-prevention of CCL. Taking the adsorption effects into account, the unsaturated permeability of the CCL is significantly affected by the adsorption distribution coefficient, contaminant concentration, initial porosity and effective saturation. The studies may be helpful to the selection of materials of CCL, provide theoretical references for designing of CCL, and ensure the safe disposal of municipal solid waste.

Abstract:To identify the softening characteristics and mechanism of soaking mudstone from Fentou formation in Chaohu area, a series of experiments were carried out on specimens prepared at different soaking time. Utilizing DB-16 ultrasound velocity-measured machine, uniaxial compression machine, the change of wave velocity through mudstone and uniaxial compressive strength were measured. Through X-ray diffractometer (XRD) and fluorescence spectrum analysis system, the mineral & chemical composition of mudstone was made clear. Finally, the microstructures of mudstone were observed by means of scanning electron microscopy (SEM), while the porosity and surface area were calculated by GIS software. The test results show that the uniaxial compressive strength and wave velocity drop obviously, the porosity of mudstone decreases slightly while surface area increases in a little extent after soaking for 90~120d, and the mineral & chemical composition of mudstone changes little. Through analyzing the test results, it is concluded that the fissure caused by the dissolution of soluble salt cementation during the saturation process is the main reason for the softening of mudstone, and the heterogeneity of mudstone is also a key factor leading to the fissure.

Abstract:This paper designed and condeuced a ten-story frame model about shaking table test, carried out the model test under low frequency,medium frequency and high frequency respectly.According model test results,using different analysis methods, including free vibration attenuation, half-power spectrum method and HHT method. Acquire the first three natural frequency and correspond model damping ratio.Then conduced the corresponding numerical simulation of the model test use Rayleigh and Caughey damp assumption.And compared the differences between different damping models.Described how to make more reasonable simulation according experiment result detailed.

Abstract:The vehicle is simplified as a one-quarter model, and the pavement structure is regarded as a foundation beam or foundation plate, by combining the two parts a vehicle-road coupling dynamics model is then established, through introducing a dynamic contact algorithm and employing the direct integration method, the differences of results obtained with coupling dynamics model and based upon static model are compared, the discrepancies of vertical acceleration of non-suspension mass at, vehicle-road interaction force P, dynamic deflections W and strains εx at specified points on pavements, shearing strain of joint sealant γ and joint load transfer efficiencies LTE(W), LTE(S) based on two models are discussed. The study showed that the results of at, P, We1 as well as γ upon two models are well agreement with each other, while the results of εx, LTE(W) and LTE(S) based on two models are of little bit difference; the vehicle-plate coupling dynamics model is suitable for simulating the dynamic responses of concrete pavements, whereas the vehicle-beam coupling dynamics model is effective to reflect the joint load transfer mechanism and joint sealant vibration. However, the models established hereof might be used to analysis of dynamic responses and evaluation of concrete pavements.

Abstract:Prediction model of freeway network incident radiation scope considered about on-off ramp was proposed based on traditional closed segment wave models. According to the different waves resulted from each phase of incident duration, six kind of situations of freeway network incident radition scope were analyzed and formulated, which could depict the interaction among traffic waves well. Then the traffic-wave class was created using object-oriented programming to simulate the whole processing of incident wave radiation in the freeway network, and GIS (Geographic Information System) map was played up to show the situation of radition scope. Finally the AIMSUN simulation test result indicates that this network radiation prediction model could represent actual incident influence range when the initial traffic volume is not extremely high, and its error analysis was carried out.

Abstract:The basic rationale for public investment in rural road projects is that households can achieve better transport access which supplies the opportunities to increase the welfare efficiently. This paper examines the impacts of rural road projects on rural household’s income using a quasi-experimental household-level panel data from Fujian Province, China, surveying treatment and control villages before and after project implementation. Rural road projects are found to improve the income of households in treatment villages, political life and the relationship with relatives and friends. However, the traditional before and after approach may overestimate income improve effect, and it has been proved to unsuitable to evaluate the impact of rural road projects on household income.

Abstract:Transportation condition is in a foundation in promoting the coordinated development of region and enhancing regional competitiveness. A good design and efficient regional transport network will further improve and promote region economic integration. This paper aims to develop a regional transportation network growth model, which based on the mechanism of physarum connecting multiple food locations via a smart network. The mechanism involves the adaptation of the tubular body: a tube thickens as the flux through it increases. A mathematical model which contains a key parameter corresponding to the extent of the feedback regulation between the thickness of a tube and the flux through it is constructed to describe the tube dynamics. The adaptive transport corridor network growth for 16 cities in Yangtze River Delta was simulated using the model. The results show that the model can simulate the regional transport network growth; the proposed algorithm based on physarum is simple and powerful.

Abstract:In this paper, magnetic field of liquid induction heating, eddy current and thermal field distribution equations are processed according to the similarities of liquid induction heating and metal induction heating, while the mathematic model, the magnetic-thermal field boundary conditions and the equivalent circuit are introduced. In this model, the material physical properties are changed by the temperature and the iterative method is used to decouple the magnetic- thermal field. The simulation analyses the magnetic field of this induction heating system, as well as the thermal field and the eddy power density. The conclusions are that the skin region supplies the most of energy for this system, and low magnetic dispersion can improve the heating efficiency. At last, the heating efficiency was predicted, and an optimal design method is proposed.

Abstract:The technology of embedding absorber tubes in diaphragm walls is a new developing direction of Ground Source Heat Pump. As the diaphragm walls are located in the ground where temperature remains constant all year around, the shallow geothermal energy may be obtained for space cooling and heating by circulating the medium in absorber tubes. According to the structure and heat transfer characteristics of geothermal heat exchangers, two heat transfer models and their analytical solutions were obtained. One model is for the section over the excavation surface, and the other is for the section under the excavation surface. The models may be employed to calculate the temperature field of diaphragm walls and the surrounding soil under non-homogeneous boundary conditions and varying internal heat source. The models may also be used to optimize the system parameters, including the layout and spacing of heat exchangers, the running time of intermittent operation.

Abstract:In order to study thermal parameters changes of the adsorbed natural gas vehicle tanks in the desorption deflated process and the influence of desorption rate and the maximum amount of desorption, heat and mass transfer model of natural gas, activated carbon adsorbents and gas tank are established. Adsorption-desorption processes are calculated within the storage tank temperature, pressure and adsorption amount of change through numerical simulation. In this paper, the author also analyzes the factors affecting the amount of adsorption and desorption, provides theoretical references for proposing the measures of thermal desorption effect. The results show that the desorption process is endothermic process, the average temperature of adsorbent reduced from 293.15K reduced to 250.46K at the end of the desorption process. Among them, the largest temperature drop is at the center of the tank, reduced 49K to 244K. At the same time, the efficiency of desorption meets a reduction of 24.49% than in the isotherm desorption. The faster the desorption process, the less the heat provided by the wall and the lower the efficiency of desorption.

Abstract:In this paper, classical buffer overflow prevention methods for Intel 80x86 architecture and C/C++ are analyzed. A new stack buffer overflow prevention method based on dual-stack is proposed due to the shortcomings of classical methods. Besides, an object file reconstructing tool for ELF format files is implemented with the dual-stack structure. Experimental results show that the proposed method and the tool is efficient for buffer overflow attack prevention with low overhead.

Abstract:A novel method of the load flow and simulation information visualization is proposed for simulating quickly and vividly the operation status of distribution systems. Combining the orthogonal list save distribution system topology and incidence matrix reflect current flow, an impedance matrix generation algorithm was designed to automatically calculate every matrix elements; a parallel Gussian elimination algorithm based on right-looking LU factorization was put forward, in order to accelerate the loop-impedance matrix equations solving by GPU; GIS and virtual reality technologies were used to visualize the result of load flow. Simulation examples show this method hasn’t special requirement for the node numbering scheme and is suitable for load flow of the radial and the meshed distribution networks for its rapid computation, high precision and visual intuitionistic display about simulation result.

Abstract:There are strict requirements on operating efficiency and performance for motor in electric vehicle. Harmonics in permanent magnet excitation magnetic field of permanent magnet synchronous motor (PMSM) can increase the harmonic components in the stator winding flux link and increase losses in the motor, which will lead to motor temperature increasing and torque fluctuation. This paper proposes a compensation of harmonic suppression control algorithm to reduce vibration and noise by reducing the stator iron loss and compensating motor torque fluctuation due to magnetic field harmonics. Simulations results show that the magnetic flux compensation control algorithm reduces harmonic content significantly, decreases torque ripple, and improves the motor’s efficiency and performance.

Abstract:Based on grain size, TOC and TN analyses of core YD0901, located in the subaqueous Yangtze River delta, we establish the Holocene high-resolution chronostratigraphy. The results show that the subaqueous delta was formed rapidly during 6~7ka (the Middle of Holocene Warm Period). Meanwhile, the mud areas of Fujian and Zhejiang were formed slowly. TOC and TN test data show that the content of TN increases around 2.7kaB.P., indicating the gradual increase of human activities in Yangtze River Basin. However, the content of TOC has not increased significantly because of the diagenesis. And the depth of MFS (34.22m) provides a reliable basis about the accurate estimation of the total amount of subaqueous delta since the post-glacial Maximum transgression.

Abstract:Lithologic-stratigraphic oil and gas reservoirs generously developed in Dainan formation of Eocene (E2d) in Gaoyou sag which located in Subei basin. Sedimentary environment and distribution of facies in Dainan formation were researched based on studying of cores, paleontology, trace elements and well-logging data. The weather condition during the depositional period was hot-and-wet subtropic-warm temperate type. Strong tectonic activities which developed during the depositional period of lower Dainan formation generated a sedimentary environment of nearshore subaqueous alluvial fan and fan delta in salty or semi-salty water, southern step-fault zone of Gaoyou sag developed subaqueous alluvial fan deposits while northern part developed delta and lacustrine deposits. Tectonic activities declined during the depositional period of upper Dainan formation, the water in lacustrine was fresh or brackish, fan delta in the south step-fault zone developed while delta and lacustrine deposits developed in the north. The sandbodies developed under that background could form main reservoirs for oil and gas.

Abstract:The Radial Tidal Sandy Ridge System (RTSRS) in the south Yellow Sea has very complex submarine topography. It is fundmental and vital for the scientific research, coastal planning and exploitation to have subtle digital terrain model, 3-dimention visual model and statistics of the different topographic units. The bathymetric survey data were recently collected in the north RTSRS using single-beam echo sounding technique. Kriging interpolation method is considered as the best choice to generate the digital terrain model for the current bathymetric data according to the residual analysis on the measured and interpolated value. The RTSRS can be visually subdivided into four topographic sub-units, including shoal, ridge, channel and broad valley through using the water-depth color bar. The microtopography of ridges and channels can be visually displayed by the profile curvature, like the sub-scale channels on the ridges and the sub-scale ridges in the channels, and quantitatively calculated in area and their percentage of the totall. Quantitatvie analyses on the slope of the ridges and channels shows the RTSRS is dominated by the horizontal-to-weakly-inclined topography with slope angle less than 5°, which accounts for 60% of the total in area and is mainly distributed on the broad valleys, the top of the ridges and at the middle of the channels. The topographic plan curvature and tangential curvature bear some information of marine hydrodynamics, in that the inner shallow region with strong currents tends to have negative value, and the outer deep region with weak currents has positive value of the tow parameters.

Abstract:This paper is mainly to study the p-forms with values in the vector bundle over a Finsler manifold. By defining the global inner product of p-forms,the codifferential operator and the Laplace operator are given. Then the equivalence between harmonic maps and harmonic 1-forms is derived

Abstract:Nowadays, droplets have plenty of applications in the field of microfluids, e.g. inkjet and micropump. However, some phenomena of droplets, such as the Marangoni effect, contact angle and evaporation, are not fully understood. The present paper compressively studied the effect of surface temperature on the evaporation process of droplets. Through analyzing the particle images of droplet middle plane, the effect of surface temperature on vortex flow inside the droplet and the effect of condensation process on contact line at the bottom of droplet ware illustrated. Then, the changing processes of droplet normalized volume and contact angle with time were plotted. The results show that as the decrease of surface temperature, the reducing rates of normalized volume and contact angle become slow. When the surface temperature is relatively low (e.g.5°C), droplet normalized volume and contact angle increase with time due to the condensation process.