Abstract:To address the longitudinal shear capacity of composite slabs，this paper finds a kind of interlocking effect existing in a new type of composite slab, which is a new kind of shear mechanism and expounds its mechanism. In order to verify the effectiveness of this type of shear mechanism, monodirectional pseudo-static tests for six composite specimens with three kinds of structural forms of the precast panel were conducted. By comparing the integral behavior of the composite slab in ultimate load, hysteric curve, self-resetting property and so on, the results indicate that, when compared with ordinary prestressed concrete composite slabs, owing to its less damage accumulation in the lamination of this new type of composite slab, the proposed interlocking effect can enhance the deformation recovery performance to some extent and ensure that the composite slabs have good interaction between the laminated layer and the precast panel to give full play to its ultimate load.

Abstract:For general engineering structure, the low order modes play a leading role in the structural dynamic response. In order to avoid an arbitrary selection of two reference vibration modes used to evaluate the two coefficients of Rayleigh damping, a formulation of optimizing Rayleigh damping coefficients based on the fundamental frequency of structure was developed. Based on the empirical equation of earthquake spectrum varying with damping ratio, the approximate solution on the derivation of response spectrum was obtained. Therefore, a formulation which includes the comprehensive effects of structural dynamic characteristics and frequency content of seismic excitation was addressed. Seismic responses of a free field subjected to 10 earthquake waves were analyzed, different Rayleigh methods were discussed, and the effectiveness of the proposed method was demonstrated.

Abstract:Based on a 8-story reinforced concrete plane frame structure, The FOSM method, the tornado diagram method and the mathematical statistics method were used to discuss the sensitivity of the top displacement to uncertainties such as the seismic intensity, the site characterization, the lateral load loading mode, the structural weight, the strength and elastic modulus of concrete and the strength and elastic modulus of the rebar. The results show that the sensitivity of the top displacement to the demand curve is much stronger than the capacity curve. Accordingly, considering the uncertainty of the demand curve and ignoring the uncertainty of capacity curve when studying the pushover analysis method based on the probability theory can not only greatly simplify the analysis procedure but also ensure the accuracy of the results.

Abstract:Three circular columns confined by low-prestressed steel belts and two normal columns were tested under axial load and cyclic lateral force, and the bearing capacity, hysteretic behavior and ductility were examined. The main parameters were the axial compression ratio and the arrangement of steel belts. Test results indicate that the seismic performance of the RC columns confined by low-prestressed steel belts was greatly improved because the development of oblique cracks was inhibited, and with the greater range of the plastic hinge region, the deformability of confined columns was enhanced.

Abstract:To study the Z-direction properties of thick plate steel, samples were extracted by different locations and directions from plate steel of different thickness and different sizes of crossing butt weld. Then the samples were supplied to simple tensile test at temperatures from -60 ℃ to 20 ℃. The principles that Z-direction property and ψ change with the thickness of the plate, the size of the weld, the difference of sampling and the difference of temperatures were analyzed. It is indicated that: fy, fu and ψ decrease with the increase of the plate thickness; fy , fu and ψ of the samples of Z-direction affected by weld are much lower than that of non-affected Z-direction, which are lower than X direction;fy and fu increase, but ψ decreases with the decrease of temperature; and the brittleness with cooling is manifested. The data of Z-direction tensile is accumulated, which can be applied in much more accurate measurement of Z-direction properties and much more rational design.

Abstract:In order to study the compression behavior of rectangular concrete joint with new type of mesh reinforcement, local compression experiments of 11 square specimens were carried out. The influence of the specimen's geometric parameters and the volumetric ratio of reinforcement on the bearing capacity was studied. With the confinement of stirrups around mesh reinforcement, the crack resistance of specimens was effectively improved. The height factor was the main influencing factor of the bearing capacity, the bearing capacity increased with the decrease of height, but specimens of higher relative height showed higher anti-cracking performance. The volumetric ratio of mesh reinforcement has some effect on the bearing capacity, but its influence was not obvious on the crack resistance. The constitutive relationship of confined concrete was adopted to build the equivalent stress-strain relationship for the core concrete of the specimens. The results of equivalent stress-strain curves calculated by the proposed constitutive relationship are in good agreement with the experiments.

Abstract:An analytical model for the reliability of the embedded depth of rigid anti-slide pile was established by introducing the bi-parameter approach used in the computation of lateral loaded pile. A reliability index target was determined by searching for the minimum of reliability index at a specified embedded depth incorporating with stochastic optimization algorithm, and was used to guide the design for the embedded depth of rigid anti-slide pile. Practical case study demonstrated that it was more economical to determine the embedded depth in the bi-parameter approach than in traditional ground coefficient methods. Analysis of the parametric sensitivity indicated that the determination of the embedded depth of the rigid anti-slide pile was more sensitive to the unit weight, internal frictional angle and cohesion of sliding mass than to the gravity of the embedded length and the proportional coefficient of ground coefficient. It is suggested that more concern be given to the variation of the former three parameters when conducting the embedded depth design of rigid anti-slide pile.

Abstract:The impacts of temperature, flow and lift of cooling water on the energy efficiency ratio of surface water source heat pump system were analyzed. The cooling load of air condition and parameters of cold water were set as control objectives, and the analytical model of energy efficiency ratio of cooling water system including energy consumption of water source heat pump was proposed. The running energy efficiency ratios of two types of surface water source heat pump systems (direct heat transfer of surface water flowing into chilling water unit directly, and indirect heat transfer through plate heat exchanger) were analyzed by using this model. The results show that the impact of change of cooling water temperature on energy efficiency ratio is bigger than change of lift of cooling water system. In partial load condition, the energy efficiency ratio of chilling water unit and cooling water system reaches the maximum when the temperature of cooling water is 23~24°C.

Abstract:Variable predictive model-based class discriminate (VPMCD) classification method was built on homoscedastic regression model. When the regression model is heteroscedastic, it will lower the prediction accuracy. So a WLS -variable predictive mode-based class discriminate (WVPMCD) pattern recognition method was presented. Its parameter estimation approach uses the weighted least square method to replace ordinary least square method to eliminate homoscedasticity, thus raising the accuracy of pattern recognition. In this paper, LCD (Local characteristic-scale decomposition) approach was adopted to decompose the roller bearing vibration signal. Then, the singular values are abstracted from the component matrix and formed into fault feature vector which will act as the input in WVPMCD. The analysis results from the roller bearing vibration signals of normal, roller fault, inner race fault and outer race fault demonstrate that WVPMCD has a higher recognition rate when the regression model is heteroscedastic．

Abstract:In order to study the fatigue life of the lift mechanism of mining wrecker and optimize the design of the weak part, a model of a rigid-flexible coupling system was established by integrating multi-body dynamic simulation and finite element method. Regarding dynamic analysis results as the random load of fatigue life analysis of lift mechanism, fatigue life contours were obtained and the minimum life was low. Based on SIMP method, topology optimization of lift mechanism was studied, and the multi-stiffness of static and eigenfrequencies were regarded as the optimization objectives. Then, the size optimization of the lift mechanism was studied. Compared with the stiffness and fatigue life of original lift institution, the performances of optimized structure are improved by 11.7% and 521%, which provides reference and basis for the design of the mining wrecker lift institution.

Abstract:The objective of this study is to compare the casualty risk of pedestrians and bicyclists in urban traffic through an analysis of real-world accident data in China. For this purpose, 438 cases were selected as samples from the accidents collected by in-depth investigation of vehicle accidents in China. A statistic measurement of the fatality risk with respect to impact speed was carried out by logistic regression analysis. Then, 21 pedestrian and 24 bicyclist accidents were further selected for reconstruction with MADYMO program. A comparative analysis was conducted on the basisi of the results from accident analysis and computer reconstructions for the fatality risk and the head dynamic response of pedestrians and bicyclists. The results have indicated that the vehicle impact speed has a significant relationship with the fatality risk of both pedestrians and bicyclists and bicyclists suffered slightly lower fatality risk compared to pedestrians. Besides, the head impact conditions such as head impact speed and impact angle between pedestrians and bicyclists are also obviously different. These findings can contribute to the setting of a more reasonable speed limit for urban traffic in China and generate strategies for bicyclist and pedestrian head protection.

Abstract:In traditional Active Front Steering System, the ideal variable steering ratio curve has the defect of non-smooth property, thus inducing torque fluctuation of the electric motor. This paper aims at designing a smooth fitting variable steering ratio curve based on vehicle model, through a comparative analysis of five different kinds of fitting variable steering ratio curves. The analysis indicates that the modified sigmoid fitting curve has the best overall performance due to its closeness to the ideal curve and mininal influence on the torque fluctuation of the electric motor. Furthermore, simulation in MATLAB/Simulink validates the good property of the modified sigmoid fitting curve.

Abstract:In order to deal with the decision-making ambiguity in practical production scheduling, this paper put forward a decision-making method based on the combination of priority rule and fuzzy synthetic evaluation. Through analysis of the task assignment process in practical production scheduling, the influencing factors relevant to task priority and machine priority were found. By using membership function to express the priority degree influencing factors, the problems of representing uncertainty and preference information in practical shop scheduling were solved. With fuzzy synthetic evaluation calculation aiming at computing the priority degree of tasks and machines, many problems in synthetic tradeoff were solved successfully. Eventually, examples were utilized to explain the calculation process of this method, and practical shop scheduling was applied to analyze the feasibility of this method.

Abstract:Some windows with low peak side lobe level and quick decay rate were used to eliminate the errors of dielectric loss factor tanδ measurement caused by non-synchronized sampling and non-integral period truncation. In this paper, the side lobe characteristic of Rife-Vincent window was discussed, and an approach for tanδ measurement based on Rife-Vincent window double spectrum line interpolation FFT was proposed. Then, the applicable rectification formulas of the interpolation were obtained by using polynomial curve fit functions. The arithmetic expression of fundamental initial phase and tanδ was deduced. The measurement system for this approach is composed of AD73360L+ ADSP-BF531+ PIC32MX460F512L. The simulation and test results show that Rife-Vincent window function can restrain spectral leakage well, and the influences on tanδ measurement, which are caused by harmonic, fundamental frequency fluctuation, sampling time length in change and white noise, are all overcome by using this approach. It can be utilized flexibly to obtain precise and steady results.

Abstract:A 450~470 MHz monolithic LNA based on 0.5 μm pHEMT was developed. The developed LNA employs resistive-shunt feedback configuration for input impedance matching, which reduces the chip size of passive elements and make it possible for on-chip fabrication. The measurement results show that the monolithic LNA has a 40 dB gain and a 0.5 dB noise figure, and the remarkable noise performance is attributed to the benefits of the absence of high-loss on-chip inductors and the low noise performance of pHEMT transistors.

Abstract:Based on the compressed sensing theory, the MP (Matching Pursuit, MP) algorithm was applied to image compression coding. This paper presented the reconstructed method of the atomic library and reduced the computational complexity of the traditional MP decomposition by using the decomposition method of the block compressed sensing image. Aiming at the low coding rate problem of the traditional MP algorithm, a coding method of MP atoms was proposed, and the coefficient of the atomic and positional parameters was encoded by using MP atomic energy and position distribution characteristics. The experiment results have shown that: 1)the decomposition method of the block compressed sensing image can effectively reduce the computational complexity of sparse decomposition; 2)that the compression coding method, besides maintaining the strengths of the traditional MP image coding, can effectively improve the coding performance and the encoding rate, and reflect the advantage of the sparse decomposition over the traditional decomposition methods.

Abstract:The impact fatigue performances of different combinations of WC grain size and Co phase cemented carbides were tested by low cycle impact test procedure, and then, their toughness and toughening effects were evaluated. The results have shown that the low cycle impact fatigue performances of cemented carbides are enhanced with the increase of cobalt content when the WC grain size is certain.The impact fatigue resistance of cemented carbide with an average grain size of 1.8 μm is weaker than cemented carbide with an average grain size of 6.5 μm at the same level of cobalt content. The low cycle impact fatigue performance is more effective than the conventional toughness indicators of cemented carbides in evaluating toughness and toughening effects.

Abstract:Cu(OH)2 precursor was prepared with fast co-precipitation method by blending CuSO4·5H2O and NaOH solution at room temperature, and calcinating to obtain nano-CuO powder. The phase, particle size and morphology of nano-CuO were characterized by X-ray diffraction(XRD), laser particle sizer and scanning electron microscope(SEM). The catalysis of different products on NH4ClO4 (AP) decomposition was investigated by thermogravimetric analyzer(DTA-TG). The solution pH,calcination temperature and reaction time were investigated. The results show that the optimum reaction conditions are determined: solution pH is 14,calcination temperature is 350 ℃ and reaction time is 10 min. The exothermic peak of high temperature decreases by 90.1 ℃ compared with that of AP without CuO.

Abstract:Non-autoclave aerated concrete was prepared with phosphorous slag with alkali-activator. The porosity and micro-morphology of the aerated concrete pore were analyzed, and XRD, SEM, DSC-TG and FTIR analysis were used to investigate the microstructures and hydration products of non-autoclave aerated concrete. The porosity of the non-autoclave aerated concrete with a bulk density of 500~800 kg/m3 is 66.79%~77.06%. The pore is elliptical and sealed, and the size of most pores is about 0.5~1.5 mm. The major hydration products of the aerated concrete are calcium silicate hydrate gel, gyrolite and hydrated calcium alumino-silicate. The CaCO3 was formed by carbonization of the hydration products.

Abstract:A silane coupling agent (named KH-550) was used to modify composite intumescent flame retardant containing tea saponin (CTS-IFR), which was applied in flame retardant coatings. The preparation conditions of the silane coupling agent modified tea saponin flame retardant(SMTS-IFR)were investigated. The structure of SMTS-IFR was characterized by FT-IR and SEM, the thermal decomposition properties were performed by simultaneous thermal analyzer, and the flame retardant and combustion performance of coatings containing SMTS-IFR(SMTS-IPRC) were also measured by Cone calorimeter. The results showed that the suitable modification reaction conditions were at the temperature of 80 ℃, the reaction time of 4 h, and the addition of 2.5% silane coupling agent in tea saponin intumescent flame retardant. It showed that the reaction between silane coupling agent and flame retardant system occured, and the flame retardant was cladded and dispersed uniformly. SMTS-IFR had good thermal stability and higher carbon residue at high temperature compared with that of CTS-IFR. Cone calorimeter test showed that coating sample containing SMTS-IFR had a good flame retardant with a heat release rate for an average of 62.29 kW/m2,a total heat release of 52.66 kJ/m2，a mean effective heat of combustion of 11.31 kJ/kg, and an average mass loss rate of 0.046 91 g/s in the combustion process, which was significantly improved compared with the coating containing unmodified flame retardant.