Abstract:Compressive impact tests were conducted on asphalt concrete, glass fiber reinforced asphalt concrete, lignin fiber reinforced asphalt concrete and polyester fiber reinforced asphalt concrete of three contents with three strain rates using the split Hopkinson pressure bar with varying cross-sections. Test results and analyses have indicated that there is a strain rate enhancing effect on asphalt concrete. Both the dynamic compressive strength and the toughness index increase with the increase of strain rate. However, the increase rates of the strength and the toughness index decrease with the increase of strain rate of the fiber reinforced asphalt concrete. Fiber content has a significant influence on the dynamic behavior of asphalt concrete. At a polyester content of 0.25%, the compressive strength and the toughness index reach their maximal values. All the fibers can improve the dynamic properties of asphalt concrete. To improve compressive strength, polyester fiber is the best, lignin fiber the second, and glass fiber the last. And to improve toughness index, polyester fiber is the best, glass fiber the second, and lignin fiber the last.

Abstract:In this study, the dynamic modulus master curves and time-temperature shift factors of asphalt mixtures were incorporated in finite element method to take into account the effects of the load frequency and temperature on the mechanical properties of asphalt mixtures. Bottom-up fatigue cracking of a typical asphalt pavement structure with flexible bases under moving load was analyzed with fracture mechanics. The results showed that one, two or three peaks of tensile type stress intensity factor ( KⅠ) at the crack tip could be induced during one passage of wheel load over the crack under various conditions, while two peaks of shear type stress intensity factor (KⅡ) always occurred，which were equal in magnitude but had opposite directions. The effects of temperature, vehicle speed and crack length on stress intensity factor and its frequency were analyzed. It was found that crack propagation was mainly controlled by KⅠ for pavements with short crack length and at low temperature, and KⅡ gradually became the main driving force for crack propagation as temperature and crack length increased.

Abstract:The mechanical behavior of rigid frame tied-arch bridge was studied on the basis of 3D finite element analysis and 1∶3 scale model test of pier-arch joint. The mechanical behavior of the prestressed concrete beam separated from the tie bar is similar to continuous beams supported by elastic supports, and is better than that of general tied-arch bridge. However, the mechanical behavior of the arch is similar to that of general tied-arch bridge. Pier-arch joint is the key part of rigid frame tied-arch bridges. Because enough studs and PBL shear connectors are arranged, and enough prestress is used, the pier-arch joint of Yongxiu Bridge has enough margin of safety and can transfer forces smoothly. The application of rigid frame tied-arch bridge on passenger dedicated railway is feasible.

Abstract:Mutual aerodynamic interference effects of stadiums have been a major problem in engineering design. Based on the pressure data acquired from the wind tunnel test of a rigid model of Zhangjiajie Stadium, the wind loads of the roof and the curtain walls of the stadium were discussed in order to study the interference effect of surrounding buildings. The interference factor method and multi-level modal force method were applied to calculate the Stadium roof's equivalent wind loads. Several conclusions were drawn. Because of interference effect, the wind loads of the roof of the stadium were much larger than those of the non-interfered parts. The interference factor of peaking negative pressures reached 1.5 and the interference factor of peaking positive pressures reached 5. Unfavorable wind pressure of curtain walls of the stadium appeared at the sag position and the corner position of curtain walls.

Abstract:Clamping force control of metal V-belt type CVT(Continuously Variable Transmission) is one of the key technologies. Because of the complexity of the metal V-belt transmission, it is hard to use mathematical model to accurately describe the clamping force formula. Large numbers of tests should be done, and then parameters should be modified on the basis of an empirical model. A clamping force test device was built, on which the clamping force relationship between the primary cylinder pressure and the slave cylinder pressure was calibrated at a steady state, and the critical clamping force was defined. The CVT efficiency was also tested. In order to judge the reasonableness of the clamping force, a clamping force test was done on a test vehicle equipped with RDC15 CVT made in China. The results have shown that the CVT Transmission meet the requirements after the clamping force calibration. Technological support will be provided for the mass production of CVT in China.

Abstract:The optimal design of a new double-chamber airbag impact attenuation system for landing equipment was addressed. The design methodology involved the multidisciplinary design optimization technology and the combinatorial optimization strategy based on the commercial software of ISIGHT, HYPERMESH, LS-DYNA and a program by FORTRAN code. The optimization objective was the airbag volume. The constraint conditions included the height and the initial pressure of the above chamber, the height, initial pressure, venting pressure, venting area, bottom area of the under chamber, the overload and the smallest distance from the ground of the landing equipment. The results showed that the airbag reached the minimum volume based on the multi-disciplinary design optimization method, and the overload and the smallest distance from the ground of the landing equipment met the design requirements. The multi-disciplinary optimization design is feasible for design of airbag to cut down development cost by reducing the design cycle and the number of tests.

Abstract:Aiming at the problems of the serious turn heavy, front-wheel shimmying and front-wheel abrasion，this paper first framed the mathematical model of the steering knuckle.And according to the given target parameters, the key point coordinates of the steering knuckle in static equilibrium state were optimized and adjusted by the optimization tool of the MATLAB software. And then, based on the result of the calculation, we created a virtual prototype model of MacPherson Front Suspension in the ADAMS software. In the end, using Genetic Algorithm combined with ADAMS, the sum of the change of four alignment parameter values relative to the given value when the front wheel was jumping up and down was optimized. Optimization results have shown that the four alignment parameter values change with the objective values. The inclined angle, the tilt angle and the toe angle are reduced within the range of 32%, 24% and 34%,respectively. The camber angle has been in the externally-braced state, the movement characteristics of the front suspension are optimized and the co-simulation is convenient and feasible.

Abstract:To address the problem of multi-motor system synchronized switching direction process control, this paper studied the reliability and stability of the wire winding system,which directly influenced the stability of roller wire speed and the performance of main axis transmission system. The mathematical model of the transmission system was built, and each essential factor,which influenced the sensitivity and precision of the transmission system,was investigated. Through theoretical analysis and experiment simulation, the transmission effect in trapezoid wire winding curve and the double cosine half-wave speed rule curve was studied. And the wire winding algorithm of single cosine half-wave has been proposed. The simulation and experiment results have proved that the transmission efficiency is high, the velocity curve is smooth and the transition time is short.

Abstract:According to the theory of cigarette filter rod glycerol spray, the glycerol spray system uses PLC and touch screen as the main controller and consists of glycerol case, controlled temperature subsystem, glycerol spray subsystem, spray valve and servo systems. This paper studied the servo systems to make the valve position precise, and this technology can realize the tracking of the speed of the running tow in real-time. The PLC(Programmable Logic Controller) created the high-speed pulse trains, which correspond to the valve position and are used by the servo systems as the given displacements. Three closed loops of position, speed and current PID(Proportion Integral Differential) control were constructed to make the valve position precise, thus realizing the uniform spray of the running tow and ensuring glycerol spray in quantity eventually, as shown in the PLC control program flow charts. The system test results have shown that the system operates reliably and the hardness of the filter-rod has reached national standard.

Abstract:Junction termination technique is quite necessary in the improvement of the breakdown voltage of a high-voltage 4H-SiC Schottky barrier diode (SBD).The 4H-SiC SBD with junction termination extension (JTE) was simulated with a two-dimensional device simulator ISE-TCAD10.0, and the 4H-SiC SBD with JTE was fabricated according to the simulation optimal parameters. Through experiment verification, a good consistency between simulation and experiment was observed. The ideal breakdown voltage was 2 000 V, which achieved more than 88 percent of the ideal parallel plane junction breakdown voltage, and the leakage current density was as low as 0.1 mA/cm.

Abstract:A polymerizable anionic emulsifier was successfully prepared by using dimer acid derived from nature，latex with this polymerizable anionic emulsifier used exclusively was prepared through semi-continuous seeded emulsion polymerization. Its emulsification and the surface tension were mensurated. The latex particle size and chemical composition were investigated by size analysis, nuclear magnetic resonance (H-NMR) and surface tension. Test results showed that this new polymerizable anionic emulsifier had better emulsifying capacity, compared with the commonly used anionic emulsifier sodium dodecyl sulfate (SDS), the critical micelle concentration of the polymerizable anionic emulsifier was 28.6 mmol / L. H-NMR and surface tension tests indicated that the polymerizable anionic emulsifier might have copolymerized with the monomer in free radical polymerization. The water absorption ratio and Zeta potential of the emulsion prepared with this polymerizable anionic emulsifier were only 2.81% after 24 hours and -70 to -60 mV.

Abstract:The impact of activation additives on the macro-physical properties of gypsum-based cementing composite was studied with comparative experiments. The hydration products were characterized by using scanning electronic microscopy and X-ray diffraction.The results have indicated that the addition of 2wt% coagulant and alkaline activator enhances the macro-physical properties of the composite. The major hydration products in the material are calcium sulfate dehydrate, calcium silicate hydrate gel(C-S-H), ettringite (AFt), and xonotlite（Ca6Si6O17(OH)2）. Moreover, a skeleton of calcium sulfate dehydrate and ettringite with high content of C-S-H gel gives better physical properties to the composite.

Abstract:To realize the production of lactic acid from glycerin, a continuous hydrothermal reaction apparatus was established, and the process for continuous hydrothermal conversion of glycerin into lactic acid was studied. A yield of lactic acid approaching to that using a batch reactor could be steadily achieved under the hydrothermal conditions of 300 ℃, 10 MPa, 1.250 mol?L-1 NaOH and continuous run of 60 min. The results also showed that, with higher alkali concentration, the yields of lactic acid decreased with reaction time, which differed from the previous results using batch reactor, and that a large amount of organic acids of small weight molecule was produced abundantly, which reduced the production selectivity of lactic acid. The results were probably related to the massive specific surface area of the reactor in the continuous hydrothermal reaction apparatus, which further promoted the decomposition of the lactic acid produced. Based on the analysis of experiment results, several suggestions on the modification of the continuous hydrothermal reaction apparatus, such as the substituting material of the reactor, the protecting preheating section of the reactor and supplying alkali twice, were put forward.

Abstract:Contrary to the current backward status of the agricultural environmental information organization in the Dongting lake area, the database optimization foundation theory of ArcSDE+SQLServer2000 was adopted. Through reorganization analysis and quality control with various agricultural data source of the Dongting Lake region in a standardization type, this paper expounded the method of designing and realizing comprehensive agro-environment information database founded on Optimizing Theory. The results have shown that the optimizing theory provides complete mechanisms of data storage and management for regional agro-environmental information database, and obtains optimized implementation in many core technologies, such as massive data organization, storage of Complex Format data, data interoperable and so on. This provides a relatively standardized and more efficient theory and technical guidance for the construction of regional agro-environmental database.

Abstract:Logarithmic Energy (LE) and Spectral Entropy (SE) were integrated to form a new characteristic, Logarithmic Energy Spectral Entropy (LESE), by using Fuzzy C Means Clustering algorithm and Bayesian Information Criterion algorithm to estimate the thresholds of the LESE characteristic, and by using dual threshold method for voice activity detection. Experiments on the TIMIT continuous speech database have shown that, compared with the Energy spectral Entropy (EE) and LE in the noisy environments, the LESE has better performance not only in detection but also in robustness. When the SNR is -5 dB, the detection error rate of the LESE is only 18.02%, and while the SNR is 0~10 dB, its detection error rate is significantly lower than the EE and LE.

Abstract:For the spatial resolution reduction of H.264/AVC stream, a motion re-estimation algorithm based on linear regression model was proposed. It exploits the correlation between the motion vectors of original video stream and those of down-sampled video, which is modelled by a linear regression model to obtain the estimated motion vectors. Experiment results demonstrate that the proposed approach can significantly reduce the computational complexity of the transcoder with only slight sacrifice of visual quality.

Abstract:The quadratic matrix equation arising from the overdamped system was considered. A cyclic reduction algorithm with cubical convergence was developed to solve the equation. In the critical case of overdamped system, the algorithm was shown to be linearly convergent with constant at worst 1/3. Numerical experiments confirmed the convergence of the proposed algorithm.

Abstract:A nonlinear SOR iteration method was used to solve a kind of HJB equation. The method is an extension of SOR iteration method from linear problem to HJB equation. Under proper conditions, it has some good monotone convergences.

Abstract:Based on the nested interest rate term structure models and general moment estimation, we have studied the statistic dynamics of the Chinese interest rate and its derivative markets with the empirical data of the Shanghai interbank offered rate (Shibor). The values of estimation and statistic inference were comparatively studied,and the results have indicated that the models most suitable to the data of the Shibor market are those that allow the conditional volatility of interest rate change to be highly dependent on the level of the interest rate.