Abstract:A simple and efficient algorithm for the generation of finite cover system with arbitrary quadrangular mathematical meshes is proposed. Both the generation of manifold elements and the coding of physical covers can be carried out conveniently by the algorithm without any additional assumptions, even for the complex problems with multiple cracks and their propagation. It is believed that the key problem in the implementation of manifold method is well solved in the present work. The proposed algorithm also lays a good foundation for a further study and application of manifold method.

Abstract:Based on the linear elastic fracture mechanics (LEFM) and the cohesive stress on the fictitious crack, the dual-G criterion characterizing the fracture behaviour of crack propagation in post-fire concrete is proposed, where, G is in terms of the energy release rate. Two important parameters, the initial fracture toughness GICini,T and the unstable fracture toughness GICun,T, are included to describe the crack extension at various stages. The quantitative relationship between GICini,T and GICun,T is established by introducing the cohesive fracture toughness GICc,T, which is conformed by the wedge-splitting experiments on the post-fire concrete specemens. Furthermore, the fracture toughness determined by energy-based method (dual-G) and stress intensity factor (SIF) is compared, and the two parameters show a good coincide with each other.

Abstract:In order to research seismic performance of flat column made of high-strength concrete, pseudo- static tests are conducted, which include six 1:3-scaled flat columns with different axial compression ratios, concrete strengths and shear span ratios. By observing the test phenomenon and analysising the data, the seismic performance of the columns including stiffness, skeleton curves, hysteresis curves, ductility and energy dissipation are obtained. It is concluded that flat columns have poor ductility and energy dissipation capacity. Based on the proper seismic measures, failure characteristic is compression-flexure destruction and the failure section conforms to the assumption of plane cross section.

Abstract:To build up a method for calculating the shear capacity of large-diameter stud connector used in high strength concrete for bridge structures. A comparative study was made of 26 groups consisting of 71 stud connector models to explore the influence of different parameters such as the concrete compressive strength, the stud diameter, the stud tensile strength and the stud length on the shear capacity of stud connectors. Formulas to calculate the shear capacity of stud connector were proposed based on the worldwide 255 test results. The results show that the shear capacity of stud connector in high strength concrete is still based on the composite behavior of the stud and the concrete. Besides, the proposed formulas are more reasonable and safe in predicting the shear capacity of stud connector in a commonly used concrete which ranges from C35 to C60. These formulas are suitable for the analysis of stud connector with diameters of 9 mm to 30 mm and length of 50 mm to 400 mm as well as the ratio of stud length and diameter over 4, used in concrete with cubic compressive strength from 15.0 MPa to 80.0 MPa.

Abstract:An approach based on spatial autocorrelation analysis was presented to identify hot spots on urban road. The application of this methodology was illustrated by five-year’s traffic crash data. Firstly, a non-parametric kernel density estimate sketched a model of two dimensional planar accident point spatial distribution. An estimation of the optimal bandwidth for accident distribution density was 115.1m and subsequently selected to create a spatial statistical unit on road segment. Then, the spatial statistical units derived from a GIS-based region-arc topology model representation of the urban road network, and aggregated attribute values of crash counts and severity indices. Finally, the Globe Moran index was employed to examine spatial distribution clustered pattern of crash data. The Local G-statistic was used to identify the clustering of low and high index values and to generate a crash hot spots map. Results of the research indicate that compared with the negative binomial model in modeling the crash frequency, the spatial analysis under integration of accident attribute data with position can not only identify hot spots on road segments (intersections) but also rank hot spots with spatial correlation according to the attribute values. Traffic management department can use spatial analysis visualized results to locate hot spots and develop further traffic safety decision-making research.

Abstract:Based on the traffic flow mechanism analysis and field data collection in merge area, the VISSIM simulation model is established and calibrated to analyze the merge capacity under the impact of a large number of container trucks. Then a multivariate regression model of merge capacity is constructed by taking into the consideration these two parameters, the traffic volume and the mixed rate of container trucks on shoulder lane. Finally, a case study is introduced to verify the model.

Abstract:The virtual partition and flexible batch TSP strategy is proposed, which is based on the cutting and fixed batch TSP strategy. And the competitive analysis of the new strategy shows the reason of the improvement. The new strategy gets improvement mainly on two aspects: on one hand, the virtual partition can maintain the arrival rate of the customer in partition area constant and make the formation time of customer group reduced; on the other hand, the adjustment of the decision time allow the new customers be taken into account in the routing plan, which are emerged between the customer group formation time and the decision time. Then the customer in the routing plan will be more, and the mean distance of the rout plan will be shorter. Finally, a numerical example proved those conclusions.

Abstract:The paper presents a function of waiting time at signalized intersection and the waiting time characteristics are first analyzed. Then, the link matrix is re-defined and the attribute table of the signalized intersection is given in this paper. Based on the assumption that the section travel times are fixed, a new labeling algorithm which is the CWTSI-SP algorithm (shortest path algorithm by taking the waiting time at signalized intersections into consideration) is presented to solve SP problem. The numeral experiment results demonstrate that with the CWTSI-SP algorithm he features of the shortest path and travel time which related to departure time at origin are analyzed. CWTSI-SP algorithm is efficiency in dynamic traffic loading analysis.

Abstract:The paper described a new methodology for performing bus punctuality studies using global positioning system and AVL（automatic vehicle location） data. It raised a bus stop-time computation model by analyzing the bus real-time position and speed. On that basis, the clear definition of Adjacent Sites Punctuality Rate was given and the more accurate computation model with extreme value theory was provided. The model was used to evaluate the bus operation between adjacent sites and key stations. Then using the AVL data of Shanghai’s No.49 bus the model’s practicality was tested. Through the logistic analysis, the results show that station spacing, cross-section of urban road, intersections, bus lane and saturation have different contribution on the value of Adjacent Sites Punctuality Rate, and the bus lane plays the largest role.

Abstract:In order to improve the safety performance of tunnel group on freeways in mountainous areas, the effects of structure length and geometric alignment of tunnel group on vehicle speed difference and heart rate increment of drivers are quantified through the analyses of changes in vehicle speed at specific sections and psychology and physiology indices for drivers on tunnel group segment. For tunnel group composed of two tunnels, the research results show that the effect of the lengths of previous tunnel and tunnel linkage section on maximum speed difference of small vehicles at tunnel linkage section is relatively obvious, and the effects of length and grade of tunnel linkage section on maximum speed difference of large vehicles at tunnel linkage section is relatively large; heart rate increment of drivers at the exit of the first tunnel is largely affected by the length of previous tunnel and tunnel linkage section, and heart rate increment at the entrance of the second tunnel is largely affected by the length of tunnel linkage section and combined influence of horizontal and vertical alignment of tunnel entrance. On the basis of validation of prediction models with the combination of existing research findings, safety evaluation methods based on speed difference and heart rate increment are provided in the paper.

Abstract:Based on the periodicity of the pavement temperature change, the estimation model is built to calculate instantaneous temperature at any depth of the pavement structure, and also the layer average temperature from the surface to certain depth. By bringing in depth conduction time τz,, the model could narrow the discrepancy due to the temperature conductivity difference of pavement materials. According to one-year pavement temperature data collected by pavement temperature observation station from Guangzhou, Ningbo and Datong, the model is applied to confirm four coefficients by estimating the least residual standard deviation between calculated temperature and the measured temperature: t1 as the time length of temperature change in short time, t2 as the time length of baseline temperature change, k1 as attenuation coefficient of short-term temperature amplitude, and k2 the attenuation coefficient of baseline temperature amplitude. Fitting results show that the residual standard value between the calculated and measured temperature is about 1℃,no further than 1.52℃, and the average residual is less than 0.5 ℃, at any or certain depth of bituminous and concrete pavement in Guangzhou, Ningbo and Datong. Thus, the predicted formula is precise and commonly applicable.

Abstract:A series of tests such as rutting test, repeated load test, dynamic modulus test and field test, was made to investigate the rutting performance of gap graded asphalt rubber mixtures ARAC13 by comparing with the modified asphalt mixture SMA13. The laboratory test results show that ARAC13 has bigger consolidated strain and smaller dynamic modulus at the consolidation stage of rutting process, and subsequently the rutting resistance and dynamic modulus of ARAC13 increased. At present, rutting tests in china cannot realize the simulation of the compaction process of asphalt mixture under confining stress, therefore, the change of the rutting performance of ARAC13 cannot obtained unless repeated load test is made. A Four year project application results show that the slope of repeated load test for 2000 cycles can be used to evaluate the rutting performance of ARAC13 and the rutting performance of ARAC13 is superior to that of the control mixture SMA13.

Abstract:Pavement images with the laser line-structured light pattern can be used to detect the pavement rut. The work principle of the laser line-structured light in rut detection is introduced in this study and a line-structured light image processing method is proposed to deal with the complicated characteristics of the pavement surface textures as well as the technical conditions. The image processing procedure can be divided into two parts, the extraction of the pavement cross-section curve and the output of the rutting parameters. The pavement transverse section curve can be obtained through three steps. First, light center extraction, which aims to find the true center of the line-structured light through Gaussian fitting. Second, light center connection, which restores the characteristics of the entire pavement transverse section by linear interpolation. Third, smoothing of the light center curve, which can reduce the impact of pavement surface texture and other interferences. The output of the rutting parameters is based on the envelope line of the pavement transverse section curve. The maximum rut depth and the rut area can be calculated as the rutting parameters, and the pavement transverse section curve can also be used to describe the characteristics of the pavement transverse deformation. The rut sample is used to test the rut measurement method and the image processing procedure above. The result shows that the line-structured light can measure the rut depth accurately and the processing procedure proposed in this work has the potential to be applicated in practice.

Abstract:The effect of thermal pretreatment with temperature between 70 and 120℃ and last for 20min on sludge organic matter solubilization, heavy metal release and anaerobic digestion was investigated. Flocs as well as cells were broken down and organic matter was released to liquid phase. Solubilisation of properties such as COD, carbohydrate, protein, DNA and ammonia all increased with temperature below 110 ◦C and experienced a significant jump at 100◦C .However, solubilisation of major organic compounds decreased at 120◦C. Cells of microorganism were broken down at 100◦C. The concentrations of heavy metals in the soluble phase increase with temperature. But no remarkable increase was observed for heavy metal release. VS removal and biogas production were investigated to evaluate the effect of thermal pretreatment on efficiency of anaerobic digestion. Both the two characteristics reached peak at 110◦C. Correlation matrices of biogas production per VS eliminated and VS removal rate with SCOD, soluble protein and soluble carbohydrates were explored to determine the influence of these selected variables on anaerobic digestion. Then the influence of soluble protein and soluble carbohydrates on biogas production per VS is illustrated by the stepwise linear regression equations.

Abstract:With formic and acetic acids as the main objective products, the experimental research hydrothermal oxidation of phenol for producing small molecule organic acids was conducted by using a self-developed continuous-flow hydrothermal reaction apparatus. The results show that the addition of alkali promotes formic and acetic production but excess alkali decreases formic and acetic acids yields. Formic and acetic acids yields increase first and then decrease with the increasing in the oxygen supply, reaction time and temperature. The highest yields of up to 9.5% and 11.2% for formic and acetic acids, respectively, are obtained at the temperature of 300 oC with the concentration of 1.0 mol•L-1 NaOH and oxygen supply of 70% for 60 s. Based on the products recognization, production pathways of the small molecule organic acids, especially formic and acetic acids, are discussed.

Abstract:Abstract：Effect of activated carbon amended ASBR on fermentative bio-hydgrogen production from glucose was evaluated at HRTs ranging from 48h to 12h with initial pH of 6.0 and system temperature of 60℃. Experimental results showed that the performance of activated carbon amended ASBRs were more stable than that of ASBRs without activated carbon addition regarding on hydrogen production and pH. Higher hydrogen yield(HY) and hydrogen production rate(HPR) were observed in the activated carbon amended ASBRs, with 65%、63%、54%、56% enhancement of hydrogen yield in smaller size activated carbon amended reactor under the tested HRTs ranges, and the maximum HPR of 7.09±0.31 L-H2/L/d and HY of 1.42±0.03 mol-H2/mol-glucose was obtained at HRT of 12h. The major soluble products form hydrogen fermentation were n-butyric acid and acetic acid, accounting for 46-66% and 30%-34% of total soluble metabolic products(SMP), respectively, indicating that the dominant H2 producers in the mixed culture belonged to acidogenic bacteria that underwent butyrate-type fermentation. In addition, higher concentration of VFA generation was observed in the activated carbon amended ASBRs.

Abstract:Based on the methods of dynamic and static, a study was made of the characteristics of removing tetracycline (TC) from drinking water by aromatic polyamide nanofiltration (NF) membrane & Reverse osmosis(RO) membrane was studied. The results showed that TCs removal by NF and RO accompanied the process of adsorption, and adsorption capacities of tetracycline by NF and RO was up to 35% and 40%, respectively. The adsorption capacity of TCs was proportional to its initial concentration，but there was no significant correlation between the equilibrium adsorption rate and its initial concentration. It elaborated the characteristic of static adsorption of TCs on the membrane surfaces fitted with Freundlich adsorption isotherms model. Besides, the significance of the adsorption of TCs by NF and RO membranes confirmed by the infrared spectrogram and scanning electron micrograph. Being kinds of adsorption sites on membrane surface for adsorbing TC simultaneously, adsorption contained membrane pore adsorption, which could lead to irreversible membrane fouling.

Abstract:Nondominated Sorting Genetic Algorithm II was used to find the Pareto front between minimum overlap of possible detection times of two events and the best probability of detection. This methodology was applied to an example network for optimizing sensor placement in water distribution systems. The solutions obtained were then compared to the ones optimized by considering probability of detection and time to detection. The proposed method performs better than the benchmark method in detecting a contamination event and identifying its possible source.

Abstract:This paper discusses the yielding and strength characteristic of friction materials. A new method is proposed to expand 2-D yield curve in p-q plane into 3-D yield surface. When applying this method on Mohr-Coulomb yield surface, a generalized yield surface is obtained. Characteristic of this generalized surface is depicted. The yield surface is applied on isotropic and anisotropic friction materials, and the result shows its ability of fitting the yielding characteristic of such materials reasonably. Finally，this yield surface is compared with four classical yield surfaces and other researchers` result. Comparison shows that it covers the scope of these classical yield surfaces thus more comprehensive.

Abstract:An approach to form a better artificial roughness of old concrete surface was proposed, and an experimental study was carried out. Firstly, the three-dimensional contour data of the rough surface of old concrete was collected by digital image method, then the data was processed based on fractal theory, and fractal dimension was used to characterize the artificial roughness; Then three-dimensional reorganization of the rough interface was achieved by MATLAB program, so that the accuracy of the digital image method was verified; Finally, the correlation of the roughness and the bonding properties of young on old concrete was investigated. The results show that the artificial roughness is a fractal structure, which can be characterized by fractal dimension; There was a positive correlation of fractal dimension (D) and interfacial bonding properties (R), which can approximately be formulated as ; Digital image method is useful in data acquisition, processing, analysis, as well as the three-dimensional reconstruction of interface morphology.

Abstract:In order to solve the problem that the present simulation methods of two-dimensional random aggregate are difficult to be applied in arbitrary gradation, this paper establishes a numerical method which can be used to determine the mass cumulative distribution function (CDF) of two-dimensional aggregate for arbitrary gradation on the basis of a statistical analysis of the diameter of aggregate on the cross sections from three-dimension model. This method is theoretically verified with the Fuller’s gradation. Based on this method, the current concrete meso-scale model is refined and a concept of sub meso-scale model is proposed to decrease the number of simulated aggregates and increase the construction efficiency of meso-scale model. Furthermore, some common aggregate gradations for fine and coarse aggregate in practical engineering are studied, and their corresponding two-dimension aggregate mass CDFs are obtained.

Abstract:Friction induced vibration and noise is one of the hottest and the most advanced research themes in the field of machinery engineering. In this paper, a comprehensive technical review on the typical automotive brake squeal has been conducted. It covers the dynamical, tribological, and tribo-dynamical studies respectively concerning experimental investigation and analysis, generation mechanisms and theories, modeling methods and prediction. The author has done the literature survey and discussed the origin of the research difficulties. Looking into the limitations of the previous researches, he proposes that the investigation be directed to the study of the uncertainty of the friction induced vibration and sound, in which the system parameters randomicity should be taken into consideration.

Abstract:Abstract: The characteristics and law of spur gears meshing were analyzed based on the elastohydrodynamic lubrication. Then a MATLAB/Simulink model was proposed for the prediction of mechanical dynamic efficiency of spur gear pairs by investigating on the computational formulas of key factors such as friction coefficient, load distribution, film thickness and so on. A period defined from the start point of meshing to the end point of meshing along line of action was divided into four parts which for an easier computation of the average sliding and rolling power losses. Meanwhile, a modifying factor was rationally introduced to account for the effect of variable lubricant viscosity. The simulation results were compared with test data and the results from other prediction models. The comparative results show that the proposed prediction model is accurate.

Abstract:The temperature field in the rear engine compartment was measured and its cause was analyzed with the bus road test for defective cooling system in the rear engine compartment. The relationship between temperature field and brake specific fuel consumption at different bus speeds is compared. The comparative study results explains why the temperature field changes with bus speeds and indicates that when the cooling capacity of the cooling system is large enough, the air mass flow of cooling air is in proportion to the heat release of the radiator. Flow field and heat transfer characteristics are analyzed in engine compartment according to the field synergy principle. A proposal is put forward to try out decreasing vortex and keeping the direction of flow and temperature gradient consistent in the arrangement of rear compartment.

Abstract:This article is based on the 2009-2011 measured meteorological data, which is recorded by small meteorological station set up in tongji university, and the effects clearness index and solar altitude on the relationship between solar radiance and illuminance are analysed. It is found that these effects are nonlinear on the whole interval, and there is slightly different in different intervals. Therefore, this paper uses piecewise linear fitting method. The clearness index and solar altitude angle are divided into 9 intervals, and linear fitting relationships between solar radiation and solar illuminance are established correspondingly. The measured data indicate that it has a higher accuracy, and it is suitable for areas which have similar latitude and weather condition as Shanghai.

Abstract:In this paper, the global optimization of a non-convex function over a sphere is investigated by the Gurman perturbation method and the canonical backward flow. The constrained optimization is converted into a singular optimal control problem for solving non-convex global optimization. A sufficient and necessary optimality condition is obtained for the non-convex quadratic optimization over a sphere.

Abstract:An investigation was made into the control variate method of Monte Carlo simulation to price Asian options by stochastic volatility model with central processing unit(CPU) cluster and graphic processing unit(GPU) devices. By taking arithmetic average Asian options with stochastic volatility under discrete monitoring time as example, an efficient control variate was chosen, and the computing efficiencies between algorithm accelerating method and devices accelerating method in CPU cluster and GPU were studied respectively. The relationship between the computation results and the parameters of the model was explored. Numerical results show that an investigation of the two accelerating methods can shorten the computation time a lot.