Abstract:Based on the shaking table tests of a six storey frame model structure made of recycled aggregate concrete (RAC), seven levels of standard for the grade classification of earthquake damage of the RAC frame structure were preliminarily put forward. The seismic performance level based on the structural damage limit state of the RAC frame structure was defined. Furthermore, a two parameter seismic damage model based on the deformation and the accumulated energy dissipation was suggested to evaluate the aseismic capacity of the RAC frame structure. The results show that the two parameter seismic damage model can well assess the damage process of the RAC frame structure system. The analysis results provide a basis for the performance based aseismic optimum design of the RAC frame structures.

Abstract:The extended finite element method (XFEM) combined with cohesive zone model was adopted for numerical analysis on seismic damaged reinforced concrete （RC） shear wall repaired with engineered cementitious composites (ECC). The simulation focused on the crack initiating and propagating in concrete and ECC and interfacial fracture between concrete and ECC. Based on that, the mechanical behaviors of the original RC wall and repaired wall were modeled for the seismic performance under lateral loads. It is shown that the method can well simulate the mechanical behaviors of the repaired shear wall with bonded interface, and numerical analysis results have a good agreement with test results in ultimate bearing capacity.

Abstract:The impact of changes in the relative height of a interfering building on main building layer lift force coefficients and lift force power spectrum was studied by rigid model pressure tests. Three side by side positions,five tandem positions and three oblique positions were considered. The results show that in the side by side cases the greater the relative height, the bigger the mean layer lift force coefficients, so as the affected height of lift force power spectrum. In the tandem cases, the relative height of the interfering building has little effect on the mean layer lift force coefficients, but it has great impact on the root mean square(RMS) of layer lift force coefficients. When the height of the interfering building exceeds that of the main building, the impact on lift force power spectrum is great, especially in the top area. In the oblique cases, the across wind spacing ratio plays a leading role in the interference law.

Abstract:Based on the analysis of the limitations of the Cook method, an improved method was proposed. The method changed the multivariate probabilistic model of directional extreme wind speeds into an univariate model. Taking the extreme wind speeds in Nanjing area as example, the results of the method and Cook method are compared. Since the method has no limitations in the probability distribution and the assumptions of the Cook method, it has more accuracy in the probability way.

Abstract:A new method for system fragility is proposed in this paper with consideration of the seismic correlation of bridge fragments (piers, bearings, abutments). Firstly, 56 structure earthquake sample pairs are obtained by uniform design, which are used to get the seismic responses of components. Secondly, the joint probabilistic seismic demand model (JPSDM) is established by Matlab. Then the corresponding capability for each component are calculated. Finally, the bridge structure system fragility curve can be obtained with Monte Carlo Sampling (MCS). The nonlinear Opensees model of a three span continuous girder bridge is established as a case study. The results prove that larger errors will be brought in if the component correlation in fragility analysis is not considered.

Abstract:On the background of a double pylon cable stayed bridge of floating system, the aseismic characteristics of cable displacement restrainers and viscous dampers was compared. The effect of hybrid application of cable displacement restrainers and viscous dampers on the longitudinal seismic response of floating system cable stayed bridge was discussed. The results show that the cable displacement restrainer is able to control the displacement response effectively compared with the viscous damper, but the viscous damper has certain advantages in the internal force control. The hybrid application can achieve the goal that cable displacement restrainers control the displacement at beam ends and viscous dampers improve the force situation at the tower bottom, which is a more cost effective seismic measure and has an excellent earthquake mitigation effect under pulse ground motions.

Abstract:The effect of longitudinal deflection on shield tunnel convergence was studied through longitudinal shear transfer and circumferential flattening. Taking the typical deflection pattern of shield tunnel as example, the effects of flattening and longitudinal shear transfer on tunnel convergence and internal forces were analyzed and compared, respectively. The results indicate that the internal forces and tunnel convergence induced by the longitudinal transfer effect are normally larger than that induced by the flattening effect. However, the effect of flattening on tunnel convergence is not ignorable with the increase of tunnel settlement.

Abstract:The minimal earth pressure on the shield tunnel face can be calculated using a new method proposed in this paper. This method takes into account the arching effect in loosening soil and the friction between cutter and soil. It is found that the distribution of the minimal earth pressure is not uniform, which is assumed by the existing methods, but parabolic. The parameters, including soil cohesion, soil friction angle, the friction angle between cutter and soil and the cover to diameter ratio, have significant influence on the minimal earth pressure. The stability of workface can be enhanced by decreasing the friction angle between cutter and soil. Finally, the results of the proposed method agree quite well with those reported in other literatures based on the existing methods.

Abstract:Based on accident data and detector data collected on two expressways in Shanghai, important variables for model construction were selected from the data of traffic flow within 5~10 min before the accident with random forest model. Then, the Bayesian network (BN) model based on the Gaussian mixture model and expected maximum algorithm was established for the analysis of real time traffic flow state and accident risk. Meanwhile, the transferability of BN model was also assessed. The results show that BN model built with selected important variables is better than that with direct detection data, with the accident prediction accuracy rate of 82.78%. The results of the transferability show that the improved BN model is still better than the traditional model, though the accident prediction accuracy of BN model decreases.

Abstract:Based on Tongji 8 degrees of freedom driving simulator, 15 samples’ eye indicators were collected using the SmartEye. The driver’s fatigue was divided into five levels, including awake, mild fatigue, moderate fatigue, severe fatigue and extreme fatigue. Taking into account of the drivers’ inter individual differences, a multilevel ordered logistic model was applied. The results show that the multilevel ordered logistic model can consider the inter individual differences among drivers effectively and improve the recognition accuracy of drowsy levels.

Abstract:A set partition model (R CP) for the crew pairing problem in urban rail transit was proposed based on practical considerations in rail transit operations. A hybrid algorithm of column generation and branch on follow ons (CGBF) was designed to solve R CP. The numerical results show that the proposed model and algorithm can meet requirements of crew pairing and yield better objective values than the existing manual methods.

Abstract:A multi line cooperation method for mass passenger flow disposal is proposed in this paper. Based on the analysis of passenger flow on transfer station platform, a multi line cooperation model is built to satisfy security constraints in the aim of minimizing the affected number of passengers. Then a genetic algorithm is adopted to obtain an optimal skip stop strategy of the model. Finally, a numerical example is taken to further explain the effectiveness of the disposal method and the application of the model.

Abstract:A dynamic interaction model of train and bridge was established considering beam rail and wheel rail relation. Based on the characteristics of high speed railway system, the rail was modeled as a discrete point support Euler beam and the motion equations of the bridge was built using a modal synthesis method. Furthermore, the effect of track irregularity, running speed and beam span on the dynamic reaction force of piers was analyzed with respect to the characteristics of simply supported box girders in China. It is concluded from the results that the track irregularity with medium and long wavelengths do not have significant effect on the dynamic reaction force of the piers. With increasing running speed, the resonance and vibration cancellation of the beam enlarges and reduces the dynamic reaction force of the piers respectively. The dynamic reaction force characteristics differ significantly under different spans, and different dynamic force frequencies caused by carbody length and wheelbase can be observed at different degrees.

Abstract:In order to investigate the effect of sulfates on the dispersibility of polycarboxylate superplasticizer and its mechanism, different kinds of sulfates with various contents were added into cement paste mixed with polycarboxylate superplasticizer. By fluidity test and Marsh time test, the effect of sulfates on the flowability of cement paste was studied. Furthermore, the rheological properties of cement paste were investigated through the rheometer, the zeta potential of cement paste was investigated through the zeta potential measurement analyzer, the competitive adsorption between sulfates and polycarboxylate superplasticizer was investigated through ultraviolet spectrophotometry, and the flocculent structure of cement paste was observed through optical microscope, respectively. The results indicate that alkali sulfates (Na2SO4 and K2SO4) have great influence on the dispersibility and retentivity of polycarboxylate superplasticizer; with the increase of dissolution of alkali ions, the competitive adsorption of sulfate ions enhances. Meanwhile, the absolute value of zeta potential decreases due to the destroyed double electrode layer. In this way, the electrostatic repulsion of cement particles is weakened and the flocculation structure becomes stronger. At a certain shearing rate, less degree of flocculation structure is damaged, leading to the decrease of rheological properties in cement paste.

Abstract:Uniaxial tension tests of transformation induced plasticity(TRIP780) steel at temperatures 298,333,363 K and strain rates 10-4,10-2, 100, 102, 103 s-1 were performed. The sensitivity of the flow stress of TRIP780 steel to temperature and strain rate was analyzed. In addition, the suitability of Johnson Cook(JC) and Khan Huang Liang(KHL) flow stress models to TRIP780 steel was discussed. The results indicate that the flow stress of TRIP780 steel shows positive sensitivity to the strain rate and negative sensitivity to the temperature, and the sensitivity of the flow stress of TRIP780 steel to strain rate decreases at high strain rate. At small strain, the JC model is more accurate for TRIP780 steel than KHL model in the flow stress prediction, while KHL model has higher precision at large strain.

Abstract:Considering the complex coupling relationship among multi carrier energy system, production system and emission system, a so called integrated hub concept was introduced, in terms of which a modeling approach for integrated energy system considering the synergy among energy, material and emission elements was presented. The case study indicates that the energy cost and benefit, the energy demand required by product manufacturing, the product benefit and emission cost directly influence the optimal results of energy system. These factors interact cooperatively to comprehensively decide the optimal strategy for energy planning and design. Thus due to the synergy among energy, material and emission the developed modeling approach could resolve the optimization problem of energy system much more systematically and reasonably as compared to the available multi carrier energy model.

Abstract:Accelerated degradation test (ADT) of a homemade kW level proton exchange membrane fuel cell (PEMFC) stack was conducted under drive cycle. The stack performance degradation was observed, as expected, with the help of polarization curve, electrochemical impedance spectrum (EIS) and V t curve. Scanning electron microscope (SEM) and transmission electron microscope (TEM) were applied to characterize the fresh and post experiment membrane electrode assemblies. The results show that after 603 h ADT, the max power output drops 21.6%. Meanwhile, the phenomenon of recoverable degradation after “rest” was preliminarily analyzed by virtue of EIS and equivalent circuit analysis. It is found that the values of constant phase angle element and faradic impedance get partly recovered, which implies that the recovery of the activity of catalyst and the hydrothermal environment in fuel cell reach an ideal condition before next cold start.

Abstract:The dynamical equations of an automatic passenger mover(APM) vehicle with middle guiding single axle tire running gears were derived by using linearized tire model, in which side force and rolling contact effect on running tire were taken into account. A simulation model of APM vehicle based on Simulink environment was built with object oriented programming technique, and the effects of contact statues between guiding tire and rail on curving performance and ride quality were studied. The simulation results show that the preload force on guiding tire do not improve curving performance but significantly worsen lateral ride quality, whereas the gap between guiding tires and rail will increase the running tire side force and guiding tire radial force on curve. The gap between guide tires and rail should be controlled in the range of 0~5 mm considering the curving performance and ride quality of APM vehicle.

Abstract:The on road emission test of a China Ⅳ diesel bus was conducted on some specific roads of Shanghai to study the real world emission characteristics of NOx and ultrafine particle. The results show that the test bus has an average speed of 20.59 km·h-1, and NOx and ultrafine particle number emission factors are 9.33 g·（km·vehicle)-1 and 5.78×1014particles (km·vehicle)-1, respectively. The on road NOx emissions mainly concentrate at middle high speed (>35~55 km·h-1) and large acceleration (a>0.5 m·s-2) driving conditions, and ultrafine particle emissions concentrate at middle high speed (v>40 km·h-1) and large acceleration driving conditions. During acceleration mode, the emission rates of NOx and ultrafine particle number are relatively high. Ultrafine particle number emission rates of four driving modes vary obviously when the particle size is smaller than 100 nm.

Abstract:In order to solve the pure time delay problem of temperature control in polymerase chain reaction (PCR) apparatus, a Matlab simulation model was built based on actual experiment data. The simulation results show that the temperature control system with the Smith predictor loop can reduce the accumulated error in integrated loop, which is caused by the pure time delay. The actual PCR apparatus can get a better temperature control effect with the method concluded from the simulation model. Finally, an optimized algorithm of proportion integration division(PID) controller was proposed to improve the robustness of the Smith predictor.

Abstract:According to the study on the failure mechanism of gear pump face seal, the key factor of face seal failure is the end plate’s overturning moment induced by the asymmetric pressure distribution in a master slave gear cavity. For a type of high pressure gear pump, the nonlinear differential equation of gear pump pressure transition zone was established to analysis the internal flow field of the master slave gear cavity. Then the test system of gear pump cavity pressure was built to verify the failure mechanism of the floating end plate of gear pump. Test data shows that the error between experiment and theoretical value is less than 5.0%. The floating end plate’s overturning moment about x axis is 56.51 N·m under rated conditions.

Abstract:In this paper, a selected transition time adjustment (STTA) based router is designed for the reliable network on chip. The router can predict crosstalk induced faults on interconnects accurately and tolerate these faults through staggering the signal transition time. Then a dual interlocked cell (DICE) is used to preserve all registers in the router from single event upset (SEU). The results show that the router can tolerate large crosstalk induced faults and SEU with only extra 46% area overhead and 70% power dissipation of a normal router. Compared with TS HC TMR and SCAC TMR based router, the router saves 93% area and 55% power overhead at least, which solves the huge overhead problem for reliable network on chip (NOC) routers effectively.

Abstract:In this paper, we propose a quality of service (QoS) multi constraints routing algorithm based on dynamic programming(QMCRA_DP), which adjusts the linear cost function adaptively and segments the feasible path intelligently. The results show that the algorithm not only has a lower computational complexity, but also increases the success rate for finding a feasible path.

Abstract:A stratified contours based surface reconstruction and multi resolution express method is proposed in this paper. First, an iterated convex hull algorithm is hired to extract the stratified contours from vertical distributed point cloud. Then, based on the stratified contours, in synchronous headway premise, the shortest circumcircle radius method is adopted to finish the triangularization processing from adjacent contours to obtain the local object’s model. After connecting the triangles in adjacent levels and unifying the normal vector for each triangle, the reconstructed surface model could be used to express the object. To convey the surface model in multi resolution, the elevation interval and horizontal resample distance is chosen as the model parameters for low resolution model generation. Furthmore, the optical parameter selection method is introduced to achieve better modeling results. At last, two case studies are chosen to verify the validity of the proposed method.