Abstract:Bridge durability evaluation is a complex process involving large amount of data and expertise which are usually imprecise and subjective. For the improvement of the effectiveness and objectivity of the evaluation process, this paper proposed a new method based on grey relation analysis and variable weight method. Influence factors for two-way curved arch bridge durability were summarized, and then a multi-level evaluation model was established with the AHP methods,and the constitution characteristics of two-way curved arch bridges were taken into consideration. Grey relation coefficient was used to evaluate the durability condition, which proved to be effective and objective. Finally, a case study was provided to illustrate the implementation process of the approach for bridge durability evaluation. The present methodology, simple in process and convenient for actual use, will greatly help decision makers and bridge inspectors.

Abstract:A new energy-dissipation system for frame-core tube structure equipped with outriggers was presented, in which vertical viscous dampers were inserted between the outrigger and the perimeter columns to make full use of the relatively big displacement of these two components. The mathematical models of the structural system were obtained with both the assumed mode shape method and the finite element method according to the simplified calculation diagram. Based on the modal damping ratio, the optimal damping constants of linear viscous dampers were determined with parametric analysis. Finally, the seismic response of a frame-core tube structure equipped with outrigger damping system was simulated. It has been shown that the outrigger damping system can significantly increase the modal damping ratios of structures, and effectively decrease the dynamic response of structures.

Abstract:In this study, a wind tunnel test was conducted for Guangzhou International Exhibition Centre. Simultaneous pressure measurements were made on its rigid roof model in a boundary layer wind tunnel. Meanwhile, a three-dimensional finite element model of the roof structure of Guangzhou International Exhibition Centre was established on the basis of the structural design drawings, and the dynamic characteristics were analyzed on the basis of the established finite element model. Furthermore, wind-induced responses of the large roof were computed and the wind loading inputs were derived from the simultaneous pressure measurements on the rigid roof model. The results showed that the influences of the structural fundamental modes on the wind-induced vibration of the roof were generally more significant than wind loads. It was also observed from the wind tunnel measurements that there was a tendency for the peak displacement response to decrease with the increase of the damping ratio. On the other hand, full-scale measurements of the wind effects on the large roof were conducted under strong wind action. Based on field measurement results, a new method to identify the first several natural frequencies of the roof in vertical direction, using the dot matrix of power spectrum density approach, was presented. Comparison of the frequency results determined by the proposed method and those obtained from the finite element model analysis was done to examine the applicability and accuracy of the proposed method.

Abstract:The basic method of H-infinity Optimum control theory was described and applied to the design of air fuel ratio controller in electronic fuel injection engine. The simulation model was established with the GT-Power software based on the physical model. In the case of outside disturbance and model uncertainty, the strategy of H-infinity Optimum was discussed and determined. The controller of H-infinity Optimum and PI was established with the Matlab/Simulink software. A real-time control system was established for electronic fuel injection engine through using the juncture between the GT-Power and Matlab/Simulink software. The simulation results have shown that the robust stability and disturbance rejection of H-infinity Optimum controller are better than those of PI controller, and H-infinity Optimum controller can improve air fuel ratio control accuracy.

Abstract:A fault diagnosis approach for rotor systems based on Local Mean Decomposition (LMD) and AR model was proposed. Firstly, by using LMD method, the vibration signal of rotor systems was decomposed into a number of product function (PF) components, whose instantaneous frequencies had physical meaning, and then the AR model of each PF component was established. Furthermore, the model parameters and the variance of remnant were regarded as the fault feature and served as the input parameter of neural networks to identify the condition and fault pattern of a rotor system. The study results have shown that both EMD and LMD method can be applied to the rotor system fault diagnosis effectively. However, the latter has better decomposition results.

Abstract:The texture analysis of the clinker image based on the grey-level co-occurrence matrix was proposed to predict the clinker's sintered quality. The best position operator and feature sets of the grey-level co-occurrence matrix were extracted with Fisher coefficient. Then, these reduced features were applied by C4.5 to classify these clinker images into three categories, over-sintered, less-sintered and normal-sintered. The experiment results have shown that six texture features, which are SA, IDM, DE, Contrast, DV and Entropy, of the grey-level co-occurrence matrix under the position operator (5,-5) have the highest degree of discriminability, and the classification accuracy reaches 95.65% with C4.5 classifier. Finally, the difference between these three kinds of clinker textures was summarized.

Abstract:A method for allocating VAR support cost based on branch's complex power components and reactive power value was presented. It is pointed out that sources' active power and loads' complex power are responsible for VAR support cost based on analysis. Based on reactive optimal power flow (OPF) solution considering reactive power value, each sources' active power and loads' complex power was modeled by each of their equivalent nodal injection current sources, and then each of sources' reactive power used for var support was modeled by a shunt reactance called “cost reactance”. Finally, the nonlinear relationship between cost resistance and equivalent injection current sources was found out on the basis of the algorithm of branch's complex power components. As a result, VAR support cost of each cost reactance was accurately allocated between sources' active power and load's complex power. Compared with the existing methods, this method is of the following properties:1) The VAR support cost of a power system is always recovered;2) It is applicable for any transmission systems of looped configurations and loop flows. It does not need any assumption and simplification, and takes into account the interaction between active and reactive power. The method proposed here gives a completely new analytical way to allocate VAR support cost. The results from the simulation of different power networks have shown that the proposed method is effective.

Abstract:According to the characteristics of reinforced concrete nondestructive testing (NDT) and the detective principle of ultra wide band (UWB) radar, a handheld high resolution UWB ground penetrating radar (GPR) system was developed. The structure and principle of the low-cost RF module with the base-band pulse transmitter, the equivalent time sampling receiver and the UWB antenna were described. Design methods of the embedded control module, whose functions included radar control, data acquisition and the image processing, were introduced. The integration of hardware and software improved the portability, the stability and the real-time implementation of the system. The prototype experiment results have demonstrated that this system can detect the protective layer thickness and the positions of Φ6 reinforcing steel bars effectively with 0~35 cm depth and intervals of no less than 6cm, and can reflect other characteristics of reinforced concrete.

Abstract:To deal with the sensor scheduling in high-speed object tracking of low earth orbit constellation, the non-myopic information increment was described as an information decision tree. Then, the optimal solution was searched with pruning technology, and a method based on the pruning of information decision tree was proposed. The simulation results have indicated that the excessive scheduling is reduced effectively with non-myopic information increment. Furthermore, the introduction of pruning technology has greatly reduced computation burden.

Abstract:Take the Condition Value-at-Risk (CVaR) as a measure of risk indicators,a two-tier optimization of electricity market bidding model was built. The upper-level objective is to solve maximizing social profits and risk problem, the bi-level optimization is the largest power generation company profit optimization. In this paper, we designed heuristic particle swarm optimization (PSO) algorithm to solve the complex two-tier optimization. The IEEE 4-bus system and IEEE 9-bus system have been tested. Numerical examples of some standard tested IEEE systems show that the new model and algorithm have better effect of computation and practical. The contrast analysis show that CVaR can more accurately measure the risk of the power suppliers than VaR

Abstract:AZ31 magnesium alloy sheets were welded by CO2 laser welding with filler metal process. The effect of different amount of calcium (Ca) additions on the AZ31 laser welded joints was studiesd, and its effect on the microstructure and mechanical properties was investigated. In the fusion zone, the grains were refined with an appropriate amount of Ca addition (no more than 0.19wt%Ca), resulting in the improved mechanical properties of the joints. The optimum welds were obtained with the AZC04 filler metal strip (0.19wt%Ca contained in the fusion zone), the grains and the precipitates in the fusion zone were both refined, and the welding efficiency of the joints was up to 100% for the base metal.

Abstract:Plain low-carbon steel with 0.2 wt % carbon (steel 20)was first treated with plasma nitriding and then was processed by salt bath chromizing at 500 ℃ for 1h, 5hs and 12hs, respectively. The microstructure of chromized layers was studied by means of optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results have shown that the chromized layer consists of CrN, β-(Cr, Fe) 2 (N, C) 1-x . By prolonging the chromizing time, the amount of β-phase on the surface layer increases and Cr7C3 phase can appear on the surface. The chromized layer formed at 500 ℃ for 12 h contains both sub-micron CrN grain area and nano-material area. The fine CrN grains can grow up to hundreds of nanometer,when there are a lot of twins or/and stacking faults in the Cr7C3 grains.

Abstract:An idea model of polycystic kidney cells CRL2830 with angiogenesis factor receptor 2 (VEGFR2) low expression was established by applying 3-D culture and shRNA technology, which can be applied to reveal the role of VEGFR2 in polycystic kidney disease. The change of biological characteristics in this cell line was observed,and the results have shown that, although VEGFR2 low expression does not affect cell growth and invasion, it can result in the volume increase of cell and nucleus and the enhancement of cell aggregation. Furthermore, the low expression of VEGFR2 can not only inhibit cyst growth but also efficiently induce early cell apoptosis in 3-D culture cells, compared with parental cells.

Abstract:Cyclohexyl-bridged cyclopentadienyl titanium catalyst of the type ［（CH2）5C（C5H4）2］ TiCl2 (C2) has been prepared by treatment of the lithium salt of cyclopentadiene ligand with TiCl4·2THF in THF solution. The complex C2 were characterized by H-NMR，13C-NMR and element analyse. Activated by MAO, complex C2 is an efficient catalyst in the polymerization of ethylene. Complex C2 displayed very high activity for ethylene polymerization under the reaction temperature of 60～70 ℃，and the viscosity-average molecular weight of polyethylene is more than 3.4×105 when reaction temperature is no more than 60 ℃ .The molecular-weight distribution measured by gel permeation reached 2.69 . High melting points measured by DSC indicates that the polyethylene produced by complex C2 is high linearity and high crystallinity.

Abstract:An integrated assessment model for the concentration parameter was proposed. Because the concentration parameter is variable in different periods of the river, an environmental health risk assessment model was developed on the basis of the integrated assessment model. Dynamic cluster analysis was used to obtain the priority of the risk management. The model was used to assess the health risk of 18 sections of the Xiangjiang River in 2007.The result showed that the health risks from As,Cd and Cr6+ were very high. By using the dynamic cluster analysis, the health risks were divided into four categories of “high”, “high-medium”,“medium” and “low”. The health risk of the Songboxia section is the highest, which fell into to the “high” category and needed priority treatment. The health risk of the Huangtuling sector fell into the “high-medium”category. The Guiyangzhen, Aozhou, Zhutingzhen, Fengxi, Baishi, Xiawan, Majiahe, Wuxing, Yijiawan and Zhangshugang sections belonged to the "medium" level. And other six sections belonged to “low” level. With reference to the integrated assessment, most of the sections were more or less polluted. Therefore, the pollution control of the Xiangjiang River must be strengthened.

Abstract:t-test method was introduced, including the principles of the method, the evaluation of characteristic ratios and the identification principle. An example was given. The identification of two different crude oils, as well as one crude oil and its weathered oil (7 days), was conducted with the t-test. In this t-test method, oil fingerprinting can be directly identified by neat graphic traits, rather than by using fussy spectra or abstract data in traditional methods, which would decrease the subjectivity and artificial distinctions of visual spectra. t-test is more reliable in presenting the quantitative index. This will be useful for the standardization and popularization of oil fingerprinting identification method. The limitations of this t-test method for oil fingerprinting identification were also given.

Abstract:Based on the advantages of the Split Bregman method, which has faster convergence rate and can make the regularization parameter constant, we have proposed the Split Bregman method to solve the second step of LOT model for image denoising. Simulation results have shown that the new algorithm is faster than the original gradient descent algorithm and can restore images perfectly.

Abstract:This paper presented a human size measurement method based on images, and designed and implemented a measurement system. Firstly, the front and side images of a tester were captured by using two digital cameras simultaneously. Secondly, the body feature points of two images were extracted in the image segmentation and feature extraction methods. Thirdly, the intrinsic and extrinsic matrixes of two cameras were calibrated. In the end, the body measure points were calculated through the feature points of two images based on the binocular vision principle, and then the body measure items were calculated. The experiments have shown that, compared withe the traditional size measurement methods, this method is characterized by automatic measurement, short measurement time and flexible operation. Compared with the 3D non-contact measurement techniques, this method features cheap and flexible equipment, and rapid speed and concise working process.