Abstract:This paper presents a new statistical identification method for structural modal parameters based on the improved random decrement technique and wavelet transform. The improved random decrement technique is used to deal with zero mean non stationary signals directly for free decay responses. The wavelet transform is applied to decoupling dense frequency and low damping system because of its advantages in time frequency domain. The bootstrap procedure is employed to evaluate and decrease the uncertainty of the identification results. The reliability of the proposed method is validated by a four degree freedom numerical example. Compared with the traditional time domain method and the wavelet transform only method, the presented method has higher estimation accuracy, especially for damping ratios. Subsequent validation results for noise resistance show that the presented method is able to identify the modal parameters stably and precisely at the presence of 15dB measuring noise, which is applicable for structural modal parameter identification under environmental excitation.

Abstract:Based on a 5 year field measurement data from the structural health monitoring system and the toll gate of Donghai Bridge (DHB), this study focuses on the dependency of the structural frequencies, including the first vertical/lateral bending modes as well as the higher modes, on the temperature and traffic loading in the prospect of periodic characteristics. The environmental effects on the frequency variation are compared by the stepwise regression analysis on such dominating periods as 1 year, 1 week, 1 day and 0.5 day. Results of this study show that the variations of temperature, traffics and modal frequencies have some long period components, and the relative importance of temperature and traffics is different for each individual period. Based on the long term field measurement data, the analysis herein can advance the understanding on the periodic variation of structural frequencies, and may lead to more reliable assessment of structural conditions.

Abstract:In order to study the lateral resistance of glued laminated timber post and beam structures strengthened with carbon fiber reinforced polymer, cyclic tests on three full scale one storey, one bay timber post and beam construction specimens were carried out. The experimental program includes cyclic test, retrofitted by carbon fiber reinforced polymer (CFRP) at the end of post and beam and retest of using the same protocol of cyclic loading. The test result shows that the CFRP retrofitting approach can restrain the development of crack, recover the lateral resistance such as strength, stiffness and ductility of the damaged structures and improve energy dissipation capacity.

Abstract:During the shaking table test, the acceleration responses of the soil mass and underground structure model, the strain responses of underground structure model were obtained. The simulative effect of boundary was evaluated by analyzing the seismic response acquired from accelerometers. At the same time, the change in natural frequencies and relative damping ratios of soil were also expatiated. And then the rules of the earthquake responses of structure model were concluded on the basis of the test result. The test results show that, compared with the only horizontal acceleration excitation, vertical acceleration excitation’s participation, whose peak was about 2/3 of the peak of the horizontal acceleration excitation, can increase the responses of the structure, and the increment of strain responses are larger than the acceleration responses. Shear deformation is a major deformation pattern for the structure model cross sections.There was a big difference between the spectrum distribution of acceleration response time history and spectrum distribution of strain response time history. Vertical vibration mode made a greater contribution to strain response than horizontal vibration mode.

Abstract:A newly proposed 2D bond model, which took the coupled effects of temperature hydraulic mechanical into consideration, was implemented into the distinct element method (DEM) software Particle Flow Code (PFC2D) to generate methane hydrate bearing sediment (MHBS) that only the bond type methane hydrate (MH) existed. MHBS samples in this simulation were in good drainage and exhaust condition. Then a series of biaxial compression tests were conducted. Results show that when the deviator stress is smaller than the peak deviator stress of pure sand sample, the sample won’t be damaged after dissociation; when the deviator stress is larger than the peak deviator stress of pure sand sample, the MHBS sample will be damaged and several undeveloped shear bands occur. In addition, several micro variables such as contact distribution, averaged pure rotation rate(APR) and quasi static velocity field, were analyzed in four dissociation phases.

Abstract:The seismic wave is generated by detonating trinitrotoluene (TNT) explosives in the soil, and the dynamic response of nodular cast iron pipeline network with flexible joints is studied. The idea and the method of the test design are introduced in detail and the main test results are presented. A preliminary analysis shows that the test design is reasonable and effective. The joint deformation has a close relationship with the systemic structure of the pipeline network. When the joint deformation is greater than a threshold value, the plastic deformation should be taken into consideration.

Abstract:Differences in vehicle load and its response on multi lane highway bridges were crucial to bridge design and related researches. These differences, especially the load effects with long loading length, were poorly illustrated by the current multi lane traffic load models. The 28 day free flow weigh in motion(WIM) data on a two lane highway and a four lane highway were offered. The data were obtained from the year 2009 to 2013. Based on the data, characteristics in the vehicle lane selection and spatial load distribution were studied. Multi lane load response with long loading length was analyzed. A new multi lane load model was proposed, based on which model coefficients values were calibrated. The results suggest that statistical stability of the vehicle and load analysis can only be ensured with a data length over 3 weeks. Vehicle and load distribution in each lane was of significant difference, indicating that the equal distribution assumption of vehicle lane load in current Chinese code was in need of modification. Variation of the vehicle load was substantial while the maximum load values were of not much difference, which suggests that the current multi lane load model can no longer satisfy the modification requirements raised by varied loading lengths. The load response ratios of different lanes with long loading length roughly remained as constants, indicating that extreme load responses in different lanes were different and would not appear simultaneously. The recommended conceptual multi lane load model provided a reasonable and scientific elaboration on the relationship of extreme load responses among different lanes and all lanes with long loading length. The model proved to be reasonable and of more engineering application value by the coefficient calibration.

Abstract:The pavement model constructed in a small test pit and compacted by a vibratory roller was loaded by a one third scaled accelerated instrument, Model Mobile Load Simulator 3 (MMLS3). The strains of different positions in the structure were collected and analyzed to explore the effective size of small scaled structure model. At present, the asphalt pavement model with cement treated aggregates base was tested. The preliminary analysis of data showed that in the zone under loading affection, the transverse strain at the bottom of the asphalt layers was tension strain and much more than the longitudinal strain. The state of longitudinal strain varied from compression to tension with the loading’s approaching and returned to the compression state with the loading leaving. The lateral strain is always tension strain. Based on the strain distribution with the distance, the effective size of the model can be determined as 100~120 cm in longitudinal direction and 50~60 cm in transverse direction.

Abstract:A calculation method of island platform width was proposed based on the behavior of passengers. By means of video identification and field observations, the transformation process and size calculation method of main functional areas were proposed, including waiting area and circulation area during the whole processes composed of waiting, alighting and boarding, and dissipating. Subsequently, based on the objectives of safely waiting and smoothly circulating of passengers, and the premise of different functional areas being independent and unoverlapped, a new calculation method of platform width, which is highly related to the length of waiting area and the width of circulating area was put forward. Finally, a comparative study showed that the calculation method overcame the defects of traditional method, and was completely adapted to the behavior characteristics of passengers and the platform operational feature of China. The study results provided a guidance for platform design.

Abstract:By analyzing the thermal principle and energy consumption of catenary system in urban mass transit, this paper summarizes the calculation methods and main influencing factors of the catenary energy consumption.The optimization strategy for improving voltage and reducing energy consumption of catenary is presented based on train operation regulation. And a model minimizing the Joule energy consumption of catenary at the most is built to optimize and regulate the train operation schedule based on communication based train control system(CBTC) with the ant colony optimization algorithm under multiple constraints.At last the optimization strategy has been simulated with the practical parameter of the urban mass transit line 2 in shanghai and its effectiveness and feasibility are verified．The proposed strategy has a guiding value for improving the contemplated schedule and real time optimal regulation of train operation arrangement.

Abstract:An on road driving data collection test lasted for 12 months was conducted on 10 taxies in Shanghai. Over 7 137 017 valid driving data were collected and then 13 789 kinematics sequences were extracted from test data, and dimension reduction and sorting treatment of kinematics sequences’ characteristic parameters were performed by principal component analysis and cluster analysis. Then according to the correlation coefficients theory, typical driving cycle fragments were selected and finally a car driving cycle of 1 163 s about the real traffic condition of Shanghai was established based on large sample statistics. The results show that the car driving cycle of Shanghai is characterized by the low average speed, high idling proportion and low cruise proportion, which shows large differences from that of new european driving cycle (NEDC). So the emission test results based on NEDC cannot exactly reflect the real traffic condition in Shanghai, and a car driving cycle based on the traffic characteristics of Shanghai should be developed.

Abstract:In order to study the development of moisture insider concrete slabs, a one dimension water movement model for early age concrete slabs subjected to external drying was established. Adomian decomposition method (ADM) as an approximate analytical solution to initial boundary value problem (IBVP) of water movement equation for moisture distributions in early age concrete slabs with arbitrary boundary conditions was derived. Comparison between numerical results by Crank Nicolson finite difference scheme and experimental results suggests that the proposed ADM based approximate analytical solution approach converges very fast and is effective for solving nonlinear diffusion equation with arbitrary boundary and initial conditions as well as any diffusivity coefficient function for external drying of concrete slabs.

Abstract:The compressive stress strain curve of EPS cement based lightweight materials was presumed based on the porous materials’ Gibson Ashby theory. The presumptions were compared with experimental results. The influences of fiber, latex, compress ratio and curing condition on the stress strain curves were analyzed. The diversification of brittle compressive strength was investigated. The relationship between compressive strength and density was also fitted according to Gibson Model. The results figure out that the stress strain curve can be treated to be formed from those of elastic porous materials and elastic brittle porous materials, and that the presumptions show good correspondence to the experimental results. Fibers, latex, compress ratio and curing condition will affect the Linear Elastic, Plateau and Densification of the stress strain curves, as well as the brittle compressive strength. The compressive strength and density of Series C, F and H can be fitted well under Gibson Model. Series L and S cannot be fitted so exactly owing to the differential of the strength of pore wall to the model.

Abstract:According to the porous electrode theory, a simulation model of lithium ion power batteries is established. The preliminary analysis of the model indicates that the internal factors which affect the battery internal resistance is the solid phase diffusion coefficient of the electrodes and electronic conductivity, ion conductivity and electrodes conductivity of the battery. The Galvanostatic Intermittent Titration Technique (GITT) is applied to a lithium iron phosphate half cell and a graphite half cell for solid phase diffusion coefficient measurement. The Electrochemical Impedance Spectroscopy(EIS) is applied to a lithium iron phosphate half cell and a graphite half cell for electrical conductivity measurement. The polarization resistance of the battery depends on the lithium ion diffusion coefficient in the anode materials. And the ohmic resistance of the battery depends on the electrical conductivity of the battery.

Abstract:The effect of torque distribution control algorithm on the vehicle economy of a four wheel drive electric vehicle was investigated. Mathematic models of key components were established based on theory and test data, and a simulation model of vehicle energy consumption was set up with MATLAB/Simulink software. To reduce the system energy consumption, a torque distribution control algorithm based on the system efficiency optimization was proposed. A torque distribution coefficient map was obtained, which avoided the timeliness problem of on line computation. Compared with the energy consumption of fixed coefficient algorithm, simulation results illustrate that the overall energy consumptions of optimal torque distribution decrease approximately by 5% in different driving cycles.

Abstract:The response of single degree of freedom (DOF) of vehicle suspension with nonlinear hysteresis characteristics under the bounded noise excitation was studied. In order to achieve the critical condition of chaotic motion of the system, the stochastic Melnikov process of system subjected to two co bounded noise excitations was derived. Then, an analysis was made of the influence of suspension hysteresis parameters on the chaotic motion. By using the Poincaré section, power spectrum and the largest Lyapunov exponent, the chaotic motion of system was verified numerically. The results show that, chaotic motion exists in the hysteretic nonlinear suspension system is subjected to two co bounded noise excitations, and it is found that when the amplitude of bounded noise excitation is small, the system does not appear chaotic motion; while the amplitude is large, chaotic motion possibly occurs.

Abstract:Mode coupling theory and energy feed in theory are both regarded as important generation mechanisms of friction induced squeal, but there have been no investigations into relationship between them so far. A two degree of freedom vibration model was established to describe the dynamics of a kind of typical frictional system with friction pairs of a lumped parameter mass and a rigid mass. The conditions of mode coupling instability were derived, as well as the relationship between mode coupling and energy feed in, when conditions of mode coupling were met, not met, or met just critical. The analysis results show that energy feed in is dependent on mode coupling theory and cannot be regarded as generation mechanism of friction squeal.

Abstract:Dry clutch semi linkage manipulation is often resorted to on congested roads, but frequent semi linkage may generate a lot of heat and cause the clutch failure. An analysis was made of the heat load of the clutch during semi linkage process. A dry clutch engagement model, an engine model and a resistance model were established respectively. A control strategy was proposed, which overcame the running resistance by controlling the degree of engagement of the clutch with a single semi linkage manipulation so as to avoid the frequent semi linkage operations. A comparative study was made of the slipping friction power before and after semi linkage control on the pavement of 2% and 5% slope as well as the pavement in good condition. Results show that the slipping friction power was reduced by 3.72 %, 36.00% and 71.35% respectively.

Abstract:In the three dimensional finite element analysis of slide valve’s reversing, calculation convergence of transient flow field may not be gained because of large mesh deformation caused by fluid structure interaction. For this reason, sliding mesh method oriented to three dimensional transient flow field analysis of slide valve is proposed in this study, using parallel sliding mesh connected between static and dynamic grid to build a three dimensional analytical model, in order to avoid calculation divergence caused by repeating reconstruction of dynamic mesh in the transient flow field. Taking the swing way of multi way valve used in hydraulic excavator as the object of the research and basing on the results of dynamic characteristics test bench for hydraulic components, the comparison between analytical and experimental results verifies the applicability of sliding mesh method in transient flow field analysis of slide valve, providing an engineered expression possibility to build mapping relationship between dynamic load of excavator and its valve’s structural morphology.

Abstract:The multi point fatigue loading system was simplified for the coupling problem occuring in case of wind turbine blade loading multi point excitation. The dynamic mathematical model was established by using the two eccentric block vibration loading as object, constructed electro mechanical coupling equations for the system, and then the electro mechanical coupling was solved by the small parameter cycle average method in resonance conditions. Electromechanical coupling characteristics and stability conditions of vibration system were obtained by the phase plane method. The mechanism of system coupling was revealed. The mechanical and electrical coupling characteristics of primary resonance, system dynamic bifurcation coupling and synchronization control were studied. The coupling characteristics of dynamic bifurcation and its avoidance method were obtained. Finally, the correctness of theoretical analysis through the test, provide guidance for the engineering application of the fatigue loading system, and which provides a reference for similar engineering application and test.

Abstract:A novel registration method for optical and Synthetic Apperture Radar(SAR) satellite images based on artificial immunity algorithm (AIA) was proposed. By taking into account of the sufficient spectral information from optical satellite image, areal features were extracted from optical image based on the image classification strategy. Then the affine transformation with initial transformation parameters was adopted to obtain the new coordinates of features according to the location of features in optical image. Finally, the transformation parameters were optimized based on AIA by using the homogeneity of corresponding areas in SAR image, which were determined by the new coordinates of areal features, as the criterion of the transformation parameters. WorldView 2 and RadarSat 2 images were used to verify the effect of the proposed image registration method for optical and SAR satellite images. It is proved that the RMSE of image registration is less than 2 pixels.

Abstract:To acquire three dimension surface deformation, a measurement method based on ant colony optimization (ACO) was proposed. It highly integrated high accuracy GPS observations from sparse ground points with the line of sight(LOS) measurements acquired by DInSAR. Two constraints, GPS and differential In SAR(DInSAR) observations, were employed in constructing the energy function based on Gibbs equation, whose minimum value was searched by the ACO operated in a continuous space. A relatively high accuracy of 3 D deformation monitoring was achieved by the proposed method, especially a significant improvement in the vertical direction.

Abstract:From both individual and organizational levels, a cross level model was proposed with a focus on the impacts of tacit knowledge on knowledge intensive organization’s performance. A questionnaire survey and Hierarchical Linear Modeling (HLM), by using hospital as the typical case of knowledge intensive organization, were adopted to carry out the empirical test. The research findings are as follows: the individual and organizational tacit knowledge have positive impacts on the corresponding performance; the knowledge sharing plays a partial mediator role between organization tacit knowledge and organization performance, while positively moderates the relationship of individual tacit knowledge and performance from a hierarchical angle; and the average level of individual performance has a significant positive effect on organizational performance. Furthermore, several suggestions on improving organizations’ performance were concluded from the prospects of deeply mining tacit knowledge, promoting tacit knowledge’s sharing and enhancing an organization’s synthesized behavior.

Abstract:A critical chain project management bias network model (CCPMBN) based on work breakdown structure (WBS) and Bayesian Network was established, which took full consideration into the temporal relations and resource constraints. The corresponding resources were proposed and the deadline of the construction was determined by Monte Carlo Model. The result shows that, with the method, the critical factors influencing the deadline can be well recognized. The proposed model provides an important reference for realizing of the construction schedule.