Abstract:By reviewing the researches of structural reliability under wind loads, such as evaluation standard, static and dynamic analysis, and directional analysis, wind direction effect and wind reliability, the wind direction effect and wind reliability in the load codes of various countries were discussed. In addition to the evaluation method of reliability, dynamic parameters, influence of wind direction on reliability and the deficiencies of present researches were analyzed. Suggestions for further research are also proposed in the end.

Abstract:Blockage effects on mean wind pressure of two square cylinders of the same height in three different layouts in uniform flow were investigated using the synchronous wind pressure measurement technique. Blockage ratios of projected areas of the building group change from 2.7% to 10.0%. The wind tunnel test results show that in uniform flow, the blockage effects on the mean pressure coefficient of the building group are similar to that of an isolated tall building. The blockage effects on mean pressure of the windward surface of the target building can be ignored, while those of side surfaces and leeward surface increase significantly with the increase of blockage ratio. In addition, adjustment factors in the formula for correcting blockage effects on mean pressure coefficient were fitted based on wind tunnel test results. Compared with an isolated building, adjustment factors for blockage effects of the building group are smaller, and blockage effects are more complicated.

Abstract:Experiments were conducted of measuring wind pressures on the surface of 3∶1 rectangular prisms with rounded corner ratio of 0, 5%, 10% and 15% in low turbulence uniform flow for the testing Reynolds number ranging from 1.1×105 to 6.8×105. The Reynolds number effects on wind pressure distributions were studied, and the mechanisms of Reynolds number effects were revealed by analyzing the variations of the flow around the model. The results show that wind pressure distributions of four models are all affected by the Reynolds number. Compared with the models with 0 and 5%, the wind pressure distributions of models with 10% and 15% are more sensitive to the Reynolds number. The corner rounding modification influences the Reynolds number effects of 3∶1 rectangular prisms by affecting the formation of the separated shear layer, which also affects the flow reattachment of the boundary layer as well as the aerodynamics of the body.

Abstract:Based on the aerodynamic wind tunnel test of two saddle tensioned membrane structures, the modal parameters were identified from free responses and responses under wind loading, the using Ibrahim time domain and stochastic subspace identification methods. Besides, the variation of aerodynamic mass and damping with wind direction, wind speed, and pretension were researched, and reasons for the difference between previous research achievements were analyzed by comparison. The results show that the aerodynamic mass changes with the wind direction, reaches the maximum under oblique wind direction, increases with the wind speed increment, and decreases with the pretension increment. In addition, the damping ratio of first order modal increases with the increase of wind speed.

Abstract:The methods for estimating the evolutionary power spectral density (EPSD) of nonstationary time series using the wavelet transform were summarized. Taking typhoon Dawei, typhoon Haikui and the winter monsoon recorded by the structural health monitoring system (SHMS) of Sutong Bridge were as examples, the EPSDs of the three measured strong winds were calculated with the Morlet wavelet. The mean values of EPSDs in the time domain agree well with the traditional Fourier based PSDs, which verifies the accuracy of the estimated results of the EPSDs. The analysis results of the EPSDs show that the energy of turbulence wind mainly concentrates on the low frequency range. Besides, the EPSDs of turbulence wind vary remarkably with time and possess strong nonstationary characteristics. Therefore, the traditional wind spectrum calculation method based on the hypothesis of the stationary random process cannot exactly describe the nonstationary characteristics of the measured strong wind spectrum. The conclusions can provide field measurement references for accurate simulation of 3D nonstationary turbulence wind field of bridges and nonstationary buffeting response analysis of Sutong Bridge under strong winds.

Abstract:Four groups of experimental tests were conducted with T shaped beam to column connections under monotonic and reversed cyclic loading. The failure modes, moment rotation curves, moment capacity, ductility and energy dissipation properties were obtained, and the effect of bolt row and self tapping screw reinforcement on the lateral performance of the connection were studied. The results show that the cracks on traditional bolted connections occur early with rapid development. The strength and ductility, especially the strength, increases with the increase of bolt row. The self tapping screw reduces and delays wood splitting, which enhances the ductility and seismic performance of the connections.

Abstract:The airflow and pressure around buildings of a typical training center were simulated using RNG kε turbulence models. The results show that considering the prevailing wind direction in different seasons, the semi closed layout is good for ventilation in summer and keeping warm in winter, which benefits outdoor activities. The pressure differences between windward facade and leeward facade fluctuates significantly with the change of height, so the corners of certain floors need auxiliary means to improve the room ventilation. Based on the analysis of wind velocity, pressure and air age around the buildings, some suggestions are offered to the improvement of resident comfort and building energy conservation.

Abstract:Based on simulation methods, this paper analyzed the influence of traffic mode characteristics and the passenger’s own characteristics on the travelling mode choice behavior of intercity passengers with a mathematical model. By comprehensive application of the production and income methods and introduction of the proportional coefficient, the calculation model of travelling time value was improved based on the fact if the passenger has his/her own cars. Based on the expression function of the distribution parameters of waiting time and the elements which cannot be accurately quantified, a simulation method for travelling mode choice behavior was systematically designed for intercity passengers. In addition, this dynamic simulation approach was illustrated with the Shanghai Hangzhou intercity transport corridors in China. The sensitivity analysis of four parameters show that the proposed simulation approach is accurate and valid.

Abstract:Three dimensional finite element model for asphalt pavement structure with semi rigid or flexible base was proposed. It was used to analyze the influence of nonlinearity of granule and subgrade soil on the mechanical responses of airport asphalt pavement under loading of aircraft B737, B767 and B777. It was shown that the influence of material nonlinearity increased as the aircraft loading increased. The influence of subgrade nonlinearity is not obvious on the mechanical response. For the semi rigid base airport pavements, the influence of granula nonlinearity and that of both subgrade and granula is little on the surface deflection at the top of the surface and the vertical compressive strain at the top of the subgrade, but is great on the tensile strain at the bottom of the asphalt concrete layers and the tensile stress at the bottom of semi rigid base. For the flexible airport pavement, the influence of granula nonlinearity is little on the surface deflection and is great on the tensile strain at the bottom of the asphalt concrete layers. Both the influence of subgrade nonlinearity and granula nonlinearity is great on the tensile strain at the bottom of the asphalt concrete layers.

Abstract:A contacting constitutive model was established by using the particle flow theory and a numerical simulation of biaxial test on GBS (graded broken stone) was proposed based on PFC2D. The reliability of the numerical method was verified by dynamic triaxial laboratory test. The plastic deformation characteristics of GBS were studied by simulation. The destruction of critical stress and that of critical strain of GBS were studied by the equation of accumulative plastic deformation. The results show that numerical test results of plastic deformation law of GBS meet the actual shakedown law. The rational damage critical strain of GBS is 2.5%. Under this critical strain, the relationship between critical stress and confining pressure is proportional with a proportional coefficient of 4.95. The increasing of confining pressure has a great effect on the resistance performance of plastic deformation of graded broken stone.

Abstract:The relationship among rollong contact fatigue crack at the gauge corner, wear and hardness of the U75V heat treated rails in field curve was analyzed by surface observation, sampling, wear measurement, laboratory photomicrograp for length and depth of the crack and hardness of the rail longitudinal cross section measurement at different traffic. The research show that there were 3 main periods during the fatigue crack growth: crack initiation and rapid propagation, co existence of crack and wear, and growth and wear control crack. The crack at the gauge corner propagated into the railhead with the angle of 10.8° to 29.4° with respect to the rail longitudinal surface. When the hardness of the heat treated layer was 340 to 360 HB and above, the wear growth rate was less than 0.015 mm·Mt-1 with rapid fatigue crack growh. The rail pre grinding from new rail installation to 5 to 10 Mt and preventive grinding with an interval of 30 to 60 Mt were recommended to balance the crack and wear. The thickness of the heat treated layer with 340 to 360 HB and above should be over 10 mm.

Abstract:To investigate dynamical behaviors of membrane water content in a proton exchange membrane fuel cell (PEMFC), a dynamic system model was established, consisting of a gas diffusion layer (GDL) and a membrane electrode assembly (MEA). The simulation results show that there is a small difference between the outputs of modified PEMFC system model and experimental data. The dynamic influence of the water content on stack voltage is plausible under more realistic operating condition. The effect of manipulating variables on chemical reaction and transfer process can also be refluxed by the modified PEMFC system model which can be used to control and analyze the membrane water content and optimize a PEMFC system.

Abstract:The effects of diesel oxidation catalyst on the characteristics of particle was studied on a heavy duty diesel engine. The results show that particle mass concentrations of measuring point after DOC decrease compared to those before DOC, and the decreasing range reduces with the increase of engine speed, but differs insignificantly with the increase of engine load. When the engine is operating at full load, the conversion rates of total particles, nucleation mode particles and accumulation mode particles decline with the increase of engine speed, with an average conversion rate of 21.5%, 26.2% and 15.4%, respectively. At an engine speed of 1 400 r·min-1, the conversion rates of total particles, nucleation mode particles and accumulation mode particles decrease first and then increase with the increase of engine load, with an average conversion rate of 34.6%, 38.8% and 27.3%, respectively. The particle conversion rates of DOC to nucleation mode particles are higher than those of accumulation mode particles, and reach the peak when the particle size range from 9 to 12 nm. However, the particle conversion rate for the rest of the particle size vary from 20% to 40%.

Abstract:The train locomotive brake pneumatic equalizer control (PEC) unit was analyzed using the bond graph dynamic modeling. The created fault bond graph was utilized to deduce analytical redundancy relations (ARRs). The whole fault signature matrix (FSM) was extracted. Besides, online monitoring using sequential probability ratio test (SPRT) was exerted to check the anomaly occurrence of the unit components. When any alert was triggered, the generated synthesized non null coherence vector was matched with the FSM to detect and isolate the possible faulty components. A simulation experiment was conducted to illustrate the feasibility of the proposed methodology.

Abstract:This paper proposed a new method to update the finite element model by using hierarchy strategy and evolutionary computation. The design variables were set to two uncoupled sub spaces, i.e. node space and section space, and were optimized by evolutionary computation. As an example, the parametric finite element model of a tower crane was constructed, and updated according to its wind induced vibration results. The results suggest that the proposed method is effective and efficient.

Abstract:Voltage Transformation Control Method for Traction Dynamic Characteristic Match of Electric Drive Bulldozer

Abstract:The hydraulic circuit with a long distance multilayer winded hydraulic hose was studied. Through transmission loss experiment, the characteristics of fluid pressure loss in this special hydraulic circuit was discovered. The experiment indicate that turbulence could also be caused by the interaction between the hydraulic hose and oil. With the whole length of hydraulic hose unchanged, the pressure loss increases with the increase of the layers of the hose curves. And in laminar status, the pressure increases linearly. The concept of hydraulic resistance was introduced to derive the half experience formula for calculating the pressure loss in the circuit of multilayer winded hydraulic hose.

Abstract:The detrital zircon dating of the modern river sands from the tributaries and mainstream of the Pearl River reveals age spectra with eight major age groups: 2 800—2 300 Ma, 2 000—1 800 Ma, 1 800—1 300 Ma, 1 100—700 Ma, 600—400 Ma, 380—230 Ma, 200—80 Ma and <65 Ma, corresponding to tectonic events within the drainage e.g. crustal growth, Lüliangian, Jinningian, Caledonian, Indosinian and Yanshanian. The tributaries are characterized with different age spectra and can be classified by their location. The Beipanjiang River, the Nanpanjiang River, the Hongshuihe River, the Youjiang River, the Zuojiang River and the mainstream of Xijiang River from the upstream feature a 380—230 Ma age peak, indicating that these zircons were mainly from the Youjiang Orogenic Belt. The 2 000—1 800 Ma age peak only occurs in the Youjiang River and the Zuojiang River, suggesting that those zircons probably come from an ancient basement. The Liujiang River from the middle stream is characterized with a 1 000—800 Ma age peak, which represents zircons from the Yangtze Block. Besides this 1 000—800 Ma age peak, another two age peaks of 660—400 Ma and 2 800—2 300 Ma are found in the Guijiang River, suggesting provenances from the Jiangnan Orogenic Belt and the Cathaysia Block. The detrital zircons from the North River, the East River and the Pearl River delta of the downstream are mainly deprived from the granite belt along the southeast coast. This result shows that the peaks of the detrital zircon ages can be used to identify the sediment from the tributaries, which may be helpful for studying the provenance of the northern South China Sea sediment and its relationship with the evolution of the Pear River.

Abstract:Detrital zircons were selected for UPb isotopic dating from Yueguifeng Formation (YF) and Lower Lingfeng Formation(LF) of the well N6 in Lishui Sag, East China Sea Shelf Basin. The results show that detrital zircons in YF are mainly magmatic zircons formed between 14090 Ma and 190170 Ma, while others are minor and mostly metamorphic zircons, older than 400 Ma in age. Apart from the above age populations, metamorphic zircons formed in 280260 Ma appeare in LF. This indicates that the provenance of YF is mainly magmatic rocks of 14090 Ma and 190170 Ma. With sustained erosion of the source area, metamorphic rocks that formed in 280260 Ma are significantly exposed and added. These permian detrital zircons with metamorphism may be related to the convergence between paleo Pacific plate and South China.

Abstract:The stability of the Hilbert C* modular generalized g frames under some perturbations was studied to see whether the family will become a generalized g frame under some perturbations related to the fixed frame. Similar to the Hilbert space, three different situations and respective conclusions were proposed, which were proved by using operator theoretic methods. Besides, the stability of the generalized dual g frame was discussed.

Abstract:An overall description of reflective and refractive problems at the interface between different materials was given. The form of universal Fresnel’s law and Brewster angle in these cases were extended using the electromagnetic field theory. Meanwhile, the presence of Brewster angle at different interfaces was analyzed. The phase relation of reflected wave field and incident wave field was obtained quantitatively. This research provides some reference for the deep understanding of the transmission characteristic of electromagnetic wave.

Abstract:An assembly optimal model combining with the immune genetic algorithm based on vaccine automatic updating (IGABVAU) was proposed to solve the assembly sequence plan problem (ASPP). According to assembly problem characteristic, four kinds of immune vaccines were proposed in which the KP and NL vaccines were set manually and the BP and NT vaccines were created automatically. The standard genetic algorithm (GA) and standard immune genetic algorithm (IGA) was compared by using a ship part assembly as an example. The result shows that the immune genetic algorithm based on vaccine automatic updating has a faster convergent speed. The KP and NL vaccines could improve the quality of assembly sequence population while the BP and NT vaccines could provide directions for next evolution.

Abstract:According to the background of industry development and the characteristics of the electric vehicle enterprises, this paper designs an electric vehicle enterprises’ niche status efficiency evaluation system. The empirical analysis of China’s electric vehicle companies using the method of super data envelopment analysis indicate that the niche status efficiency is closely related to the use efficiency of complementary assets. The support resource factors such as the policy and financial support from government and the innovation resource factors such as scientific research personnel are the key complementary assets of electric vehicle enterprises’ niche and have an important influence on the diffusion of electric vehicle products.

Abstract:In order to find the supplier trade credit pricing strategies in two echelon supply chain it is reasonable to consider the default risk in decision making. The optimal decisions were investigated on two echelon centralized and decentralized supply chain. The realization of the coordination of supply chain was discussed by considering the pricing of the trade risk premium from the perspective of the supplier who is the leader in the supply chain. The result show that the pricing on trade credit for the coordination of supply chain and on the capital market complies with the same rule, that is, the higher risk corresponds with the higher profit as the capital asset pricing model indicates.