Abstract:Slopes with red beds are often reinforced by anchors. But the disintegration characteristics of the red sandstone have direct influence on the mechanical properties of the anchors. Thus, it is required to study the laws between the disintegrating resistance characteristics of the red sandstone and the mechanical properties of the anchors. In this paper, anchor pullout tests in red sandstone layers and disintegrating resistance tests of red sandstone were carried out. Firstly, the evolution rules of the load-displacement curves and the loading elastic-plastic displacement curves of the anchors in red beds under cycling loads were obtained through anchor pullout tests. Secondly, the disintegrating resistance index was acquired under the disintegrating resistance tests. At last, the laws between the disintegrating resistance characteristics of the red sandstone and the mechanical properties of the anchors were combined. The analysis shows that, with the reduction of disintegrating resistance index, the mechanical properties of the resistance of pullout become poor.

Abstract:The performances of traditional tuned mass damper (TMD) intended for suppressing the vortex-induced oscillation of bridges were invesitgated. In order to improve the robustness of traditional TMD, multiple tuned mass dampers (MTMD) theory was proposed to design TMDs. Furthermore, a new damper, namely the eddy current damper, was developed to repalce traditional oil damper as the damping producer of TMD, so the fatigue life-span of TMD was greatly extended. The parameter design of MTMD was realized by making use of genetic algorithm. And the results of comparison between TMD and MTMD have indicated that MTMD is superior to TMD, when their effectiveness and robustness are of equivalent importance in design. Both experiments and engineering practice of eddy current TMD were successfully conducted, showing a promising future of eddy current TMD in the field of bridge vibration control.

Abstract:Multiple assumptions and approximations in nonlinearity analysis models of existing reinforced concrete beam element result in low calculation efficiency and low calculation accuracy. In this paper, based on co-rotational procedure, a numerical model for a given section considering material and geometrical nonlinear analysis of reinforced concrete beam element was developed. Firstly, by means of virtual work, a tangent stiffness matrix for the material nonlinearity of perfectly-bonded reinforced concrete beam element was derived in co-rotational coordinate system. Then, by building total and incremental relationships derived from differential equations of nodal displacements and forces between global coordinate system and co-rotational coordinate system, respectively, tangent stiffness in global coordinate system reinforced concrete beam element was developed by considering geometric and material nonlinearity. A comparison between the results in this paper and those from existing references has demonstrated that the algorithm developed is highly efficient and accurate with many advantages, such as non-cumulative calculation errors and reduction in computation.

Abstract:To discuss the seismic behavior of RPC box piers, a nonlinear analysis program was compiled with the fiber element model by taking into account secondary effects of the axial force, in which the horizontal load under variable loading direction could be simulated and the whole loading process including the unloading could be analyzed. Based on the contrast analysis between cyclic loading test results of three RPC box piers samples under the invariable axial force and the calculation results, the precision of the program was proved. Factors affecting the seismic behavior of RPC box piers under the variable horizontal loading direction were analyzed, including axial compression ratio, reinforcement ratio, length-width ratio and opening ratio of the section, and the relationship between the most unfavorable loading direction and length-width ratio of the section was obtained.

Abstract:Settlement difference of tunnel-bridge section results in the bump when vehicles pass, which reduces driving comfortableness. In this study, the process of vehicle passing tunnel-bridge section was regarded as a forced oscillation with certain initial conditions. Considering vehicle rotation and overturn in longitudinal direction, a dynamic model of vehicle-road was established, and a vibration equation was given. And the driver acceleration and impact force to road with various influencing factors were solved with Laplace transform. The result shows that the acceleration and force are influenced significantly by settlement difference and vehicle load, while the vehicle speed has little effect on them.

Abstract:Shaking table tests of a 1∶20 scale model of a 3 MW wind turbine tower were carried out under the excitation of near-fault ground motion with fling step. Rolling-ball vibration absorbers were designed to mitigate the tower's dynamic response. A record with fling step from 1999 Chi-Chi earthquake at TCU052 station was chosen and the record without fling step was obtained by filtering the former record through a 4th order Butterworth filter. The nonlinear dynamic responses of the model without absorber were studied and compared with the results from finite element analysis. Then, the effectiveness of one-ball vibration absorber and multi-ball vibration absorber with the same total weight was examined under the excitation of the record with fling step. The results show that the near-fault ground motion with fling step greatly magnifies the tower's responses. It should be noted that this effect cannot be neglected when a wind turbine tower is designed and constructed in seismic zones. The ball vibration absorbers can reduce the standard deviations of dynamic responses to about 60%～70% of those without absorber. The performance of the multi-ball vibration absorber is superior to that of one-ball vibration absorber.

Abstract:This paper presented the axial compression test on six lipped channels of cold-formed steel. The influence of aspect and slender ratio on static performance was studied by testing four of them. And the other two composite members were considered to prove the improvement of composition effects. The test indicated that aspect and slender ratio, as well as eccentricity were the key factors influencing the plate effects and buckling mode. Composition effects could greatly improve the bearing capacity, and the buckling mode was influenced by various combination forms. Lastly, considering geometry, material nonlinearity and initial defect, this paper created the FEM mode and analyzed the rules after the comparison between the test and FEM, both of them matched each other well.

Abstract:Generalized inter-story drift spectrum, in which the existing structures are equivalently simplified as combined shear-flexural beams and the FEM models, was used to analyze the influence of a subway station, which was supposed to be buried in three types of homogeneous foundations respectively on the inter-story drift and anti-seismic performance of nearby buildings. It is illustrated that the existence of subway station will increase the inter-story drift of adjacent structures, which is harmful for the safety and the seismic performance; the influence of the subway station decreases gradually as the distance of the building to the subway station increases. According to the cases analyzed in this paper, the influence of the subway station is the most significant when the station is buried in soft site. Moreover, the approximate range of influence of the subway station in special site conditions were given and discussed: for the soft site condition, the buildings away from the station with a distance 2.0 times the length of the station will still be affected; and in the hard site, the calculations obtained from the conditions with and without the subway station are almost the same when the distance equals to 1.5 times the length of the station.

Abstract:In order to meet the requirements of locating fault causes of continuous work equipments or units in petrochemical enterprise quickly, an ontology based fault tree construction method was proposed. In the proposed method, the fault tree is generated from domain ontology, and then the ratio of efficiency to time for fault diagnosis is obtained through the quantitative analysis of the fault tree. At last, the optimal fault diagnosis path can be obtained according to the descending order of the ratio of efficiency to time for fault diagnosis. This method combines the advantages of ontology and fault tree, and it realizes rapid fault causes locating based on knowledge sharing and reuse. Application example shows that the efficiency of fault diagnosis can be increased and the costs of enterprise's maintenance can be reduced by using the proposed method.

Abstract:A method of extraction prospect, which uses the background image LBP (local binary pattern) texture and current frame image LBP texture similarity analysis, was put forward. This method overcomes the sensitivity to illumination methods in vehicle detection, such as frame difference method and background difference method. The Camshift tracking algorithm combines the H,S and V components, the improved LBP texture of the joint histogram with the centroid tracking by pyramid L-K optical flow. This method can effectively solve two problems: one that the similar background color may lead to the tracking of the target area bigger, and the other that the search window position accuracy is low when dealing with large displacement between frames of video. The experimental results prove that the method has good detection and tracking effect.

Abstract:In order to overcome the drawback of traditional method directly using image features to classify images, which will produce the problems of feature redundancy and low accuracy，a new approach based on Covariance Descriptor and LogitBoost was proposed for the image segmentation of traffic scene. The motion and structure , texture and HOG features were extracted for segmenting image. Meanwhile, the covariance descriptor was used to fuse the features mentioned above to reduce the feature redundancy.The multiclass LogitBoost classifier was used for image segmentation to improve the accuracy of segmentation. Experiments on the public CamVid dataset were preformed to test and evaluate the proposed method, and the results showed that this method was effective.

Abstract:In order to improve dynamic performance and reduce the vibration produced by high-speed industrial sewing machine, a method of dynamic balance and optimization was applied to improve the key mechanisms, the puncturing and stirring mechanism, of the sewing machine. A dynamic model of puncturing and stirring mechanism was built in the dynamic simulation of mechanical system. The sensitivity of each variable on the analysis target- RMS of the vibration force and vibration moment was analyzed. Response surface approximate models, which express the approximate relationship between the design parameters and the analysis target, were established and verified. The reasonable values for weight coefficients were assigned and confirmed to build the optimal mathematical model. The optimization of sewing machine was carried out by means of optimizing parameters, such as mass and placement of the mass centroid of mechanism, based on MIGA. The vibration force and vibration moment of the puncturing and stirring mechanism were significantly improved after optimization. The optimization results indicate that these methods have high accuracy and validity, which has reference value for solving the vibration and noise of complex mechanical systems such as high-speed industrial sewing machine.

Abstract:A new multi-infeed HVDC system that comprises inductive filtering device has been modeled on the basis of the CIGRE model. The definitions of Multi-infeed Effective Short Current Ratio (MESCR), Multi-infeed Interaction Factor (MIIF) and Commutation Failure Immunity Index (CFII) have been explained. The varying pattern of CFII in different fault types and different fault time has been analysed in comparison. The impact of the resisting capability on continuation commutation failure of multi-infeed HVDC systems by ac system strengths in the conditions of local commutation failure and concurrent commutation failure have also been studied in comparison. The theoretical calculation and simulation analysis shows that the inductive filtering device enhances the MESCR and CFII of the multi-infeed HVDC system and significantly decreases the risk of concurrent commutation failure and local concurrent commutation.

Abstract:In order to equip unmanned underwater vehicles with the capacity to passively localize long-range sources in shallow water, a localization approach which combines the flank array of unmanned underwater vehicle and matched-field processing was proposed. The proposed approach can be used as an unmanned underwater vehicle cruising at a low speed along a straight line at a certain depth and gathering data at sampling positions. Matched-field processing data received by the flank array at each sampling position provide the primary localization capacity. Furthermore, combining and analyzing already generated matched-field localization outputs can improve the localization performance against the lack of spatial gain due to the limited physical size of the flank array. It enhances the robustness to ocean environmental mismatch and position errors of the flank array, the stability in the estimation process, and the output signal-to-noise ratio. The three-dimensional coordinates of the source of interest can be gradually estimated over time. The ability of the proposed approach is examined through the synthetic test cases at different signal-to-noise ratios, and satisfactory results can be obtained in all cases. Additionally, the localization approach is proper for practical situations because the system requirement is not high.

Abstract:Isothermal compression tests of 4045 aluminum alloy were carried out at the strain rate range of 0.01~10 s-1 and at the temperature range of 300~450 ℃ on Gleeble-3500 system to study the hot deformation behavior and hot workability. The results show that the flow behavior of 4045 aluminum alloy can be described by the hyperbolic-sine equation with the average activation energy of 189.93 kJ/mol. The processing maps were calculated on the basis of the dynamic materials model (DMM).The optimum processing parameters were obtained at strain rate range of around 0.1~0.3 s-1 and deformation temperature range between 380 °C and 450 °C on the basis of processing map and microstructural evolution analysis.

Abstract:The strength change of alkali-activated slag cement pastes (AASC) exposed to the hot environment from room temperature to 1 000 ℃ was studied. The phase composition and microstructure of AASC were also examined by using DSC/TG, XRD and SEM.The results indicated that the change of AASC activated by water glass was similar to the AASC activated by sodium hydroxide. The loss of evaporative water in AASC at 200 ℃ densified the microstructure of hardened pastes, resulting in an increase in compressive strength but a decrease in flexural strength. When the AASC were heated from 400~ 1 000 ℃, both flexural and compressive strength decreased continually. Particularly, the strength dropped significantly in the range of 600 ~ 800 ℃ due to the phase reaction leading to the formation of gehlenite.

Abstract:To solve the problem of too much identifying times and data transmission in some binary tree-based algorithms, an enhanced binary tree-based anti-collision algorithm for Radio Frequency Identification (RFID) system was proposed. The algorithm makes full use of the information of last query, and tags respond to reader in succession according to the first collided bit. Therefore, the probability of collision can be decreased. Reader stops receiving remaining bits immediately while detecting two collision bits in the received data, which can reduce the transmission of redundant data. The algorithm divides all tags into many subsets and adopts backtracking strategy. The simulation results show that the algorithm significantly improves the identification efficiency.

Abstract:A multi-core system was designed based on the message-passing programming model. Within a 4×4 2D mesh Network on-Chip (NoC), this system integrated 16 small RISC processors, each equipped with a configurable private SRAM for instruction and data storage. Inter-processor packet communication was conducted via the wormhole switching routers and network interfaces. At the software level, some basic routines for data exchanging and process synchronization were implemented. Besides, 3 applications were designed by using SPMD parallel pattern for system verification and performance analysis. Simulation and FPGA test has shown that, for integer matrix multiplication, floating point FFT computation and template matching of gray images, this multi-core system can achieve a speed up to 7.6, 10.5 and 15.9 respectively.

Abstract:Through the construction of rough concepts in formal concept analysis, we introduce several completions for posets in this paper. After that, we construct a formal context from a poset, and discuss the relationship between the completions and rough concepts. It is shown that the completions proposed are isomorphic to Dedekind-MacNeille completion.

Abstract:This paper is concerned with the L1/2 regularization problem. We first study the optimality conditions for the problem. The optimality conditions obtained are the extensions of the optimality conditions for the minimization of a smooth function. Based on this, we derive a decent direction.We then develop a descent method for solving the problem. The method can be regarded as an extension of the well-known steepest descent method. Under appropriate conditions, we show that the proposed method is globally convergent.

Abstract:To build the Financial Agglomeration Competitiveness Evaluation Index System from the aspects of economic scale and the scale of financial agglomeration, the factor analysis method and Wilson largest Entropy Theory were applied to comprehensively evaluate the Financial Agglomeration Competitiveness and radiation field of Pearl River Delta Economic Circle City. The empirical results show that the Pearl River Delta Economic Circle has formed a network of mutual radiation pattern between the cities, and also constructed index system which makes the Financial Agglomeration evaluation more scientific. This article divides the Pearl River Delta cities into a three-tier financial growth pole with the economic development circles, so that the economic circle has a dual demonstration effect of radiation.