Abstract:To study on mechanical properties of non-metal faced sandwich panels under bending load, the force-deformation relationships of differential equations were used to derive and simplify deformation calculate formulas and bearing capacity calculate formulas of the single-span simply supported sandwich panels under uniformly distributed load and concentrated load, considering the influence of the shear deformation of core. Bending properties of two groups of sandwich panels with calcium-silicate (CS) faces and polyurethane (PU) cores were tested through vacuum chamber loading and sandbag loading and they were analyzed through the finite element methods (FEM) with software ABAQUS. Bending deflection and bending bearing capacity of sandwich panels in serviceability limit states and bearing capacity limit states are got separately and the corresponding load-displacement curves are drew. The results show that the theoretical calculation results are identical to the experimental results and FEM results. It is concluded that the simplified formulas can be used to calculate accurately bending deflection and bending bearing capacity of non-metal faced sandwich panels.

Abstract:The responses of main building under different strong earthquakes, such as El Centro, Taft, Wenchuan-Jiangyou were compared, and dynamic time history analysis based on Wenchuan-Jiangyou record with different peak values was used to reveal the damage mechanism of this typical structure. The results indicate that the response of Wenchuan-Jiangyou record is the smallest, but variability is the biggest. Wenchuan earthquake, which is more than design intensity, does not cause serious damage of main building. The torsional effect is remarkable, and coal scuttle layer is always weak layer. The stiffness degradation of frame is faster than the bent part, and the proportion of bent part within total earthquake action is enhanced firstly and then remains same. But the overall proportion is still in low level and bent part is unable to become the second resistance component. Although space grid roof system in turbine hall does not collapse because of strength failure of components, the bearing carries over huge shearing force with oversized distortion, and the failure of bearing will lead to collapse of roof system. Plastic deformations mainly concentrate in the first floor and coal scuttle layer, and “strong beam and weak column” are exposed.

Abstract:To investigate the natural vibration characteristics of the 160 000 m³ full capacity liquefied natural gas (LNG) storage tank, a fine finite element model for the tank with reasonable element types and mesh dimension was established using the finite element software (ANSYS). Using direct coupling method for the fluid-structure coupling constraints and the reduced mothed for analysis, the natural vibration characteristics of the tank is obtained when the tank is empty or full and leak at full or harf full liquid level. The liquid's influence on the vibration characteristics of tank structure is given. Besides, the influence of the prestress, the pressure of the gas and the constraint at the bottom of the outer tank structure is considered. The research results above can provide a reference basis for engineering design of the LNG storage tanks.

Abstract:Nano-zero valent iron (NZVI) was employed to remove Se(IV) from groundwater. The kinetics of Se(IV) removal by NZVI as functions of pH, initial selenite concentration and reaction temperature were investigated and the reaction products of Se(IV) with NZVI were determined with X-ray Absorption Near Edge Structure Spectroscopy (XANES). The results demonstrated that the Se(IV) could be rapidly removed by NZVI with pseudo first order reaction rate constants decreasing from 0.339 to 0.149 min-1 as pH increased from 4.0 to 7.0. Moreover, the removal rates of Se(IV) by NZVI at pH 6.0 dropped with elevating initial Se(IV) concentration. The activation energy of Se(IV) removal by NZVI was determined to be 26.26 kJ·mol-1. The XANES analysis unraveled that Se(IV) was removed by NZVI via adsorption followed by reduction to Se(0).

Abstract:An investigation was performed for the simultaneous determination of norfloxacin (NOR), ciprofloxacin (CIP), enrofloxacin (ENR), and ofloxacin (OFL). The developed method was successfully applied to analyze the fate of Fluoroquinolones (FQs) in water treatment processes. Four FQs were found in Yangtze River, Taihu Lake, Dasi Reservoir, Songhua River, and drinking water treatment processes of A,B and C in Jiangsu. Analyses of samples from Yangtze River, Taihu Lake, Dasi Reservoir and Songhua River indicated that FQs were present at concentrations of 51-9,5-4,2-248 and 61-165 ng／L, respectively. FQs residues in water treatment processes show that the removal efficiency of conventional water treatment processes is between 20％ and 40％, and the coagulation-sedimentation process plays a dominant role. The removal efficiency of ozone-activated carbon process is about 20％-60％.

Abstract:To improve the visible light photocatalytic (PC) activity of TiO₂ photocatalyst, the well-aligned TiO₂ nano-tubes (TiO₂ NTs) were in-situ grown by anodization of Ti foils, and the graphene film was anodic electrodeposited onto the aforementioned TiO₂ NTs to constructed graphene film decorated TiO₂ NTs (GF／TiO₂ NTs) photoelectrode. Apparent morphology, surface composition and light absorption ability of the resulting photoelectrodes were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and UV-visible light diffuse reflection spectroscopy (UV-vis DRS). It was found that the graphene were successfully decorated onto the surface of TiO₂ NTs electrode, and existed as the transparent film. In addition, the light absorption of GF／TiO₂ NTs photoelectrode was greatly red-shifted to visible light region. Furthermore, the methyl blue (MB) was served as the probing molecules, and the effects of deposition voltage and deposition time on the PC performances were mainly investigated. It was found that when the deposition voltage and applied time were +0.8 V and 10 min, respectively, the optimal photodecomposition of MB could be obtained. Under the simulated sunlight irradiation within 120 min, the 65.9％ degradation rate of MB could be achieved, which was 1.35 time larger than that of pristine TiO₂ NTs photoelectrode.

Abstract:To fulfill photocatalytic H₂ production under visible light irradiation, (CuAg)_xIn_2xZn2(1-2x)S₂ photocatalysts were synthesized using the precipitation and calcination. X-ray diffraction (XRD), ultraviolet-visible absorption spectra (UV-Vis), dynamic light scattering (DLS), energy-dispersive X-ray spectroscopy (EDS), and inductively coupled plasma mass spectrometry (ICP-MS) were employed to investigate band structures of the photocatalysts and evaluate photocatalytic activities. The results show that the absorption edges shift to longer wavelengths up to visible-light region and band gaps decrease with the increase of x. In addition, the conduction band potentials are close to the redox potential of H+／H₂ with the increase of x. The prepared (CuAg)_xIn_2xZn2(1-2x)S₂ (x=0.05-0.30) photocatalysts exhibit the activities of H₂ production under visible light irradiation, and (CuAg)0.15In0.3Zn1.4S₂(x=0.15) shows the highest photocatalytic activity. The band structures of (CuAg)_xIn_2xZn2(1-2x)S₂ were manipulated by adjusting the composition ratio, which will help design visible-light-response photocatalysts with the high activity and stability.

Abstract:To improve the nitrification efficiency of activated sludge in a low temperature (15 ℃） sequencing batch reactor (SBR), the performance and characteristics in nitrification of the activated sludge were investigated by batch culture with regulation of initial pH. The results indicated that the ammonia oxidation efficiency of the activated sludge was the best with initial pH ranged from 8.0 to 9.0. In the NO₂--N accumulating process, the specific ammonia nitrogen (NH₄+-N) removal rate and specific nitrite nitrogen (NO₂--N) producing rate were 25.49 g·kg-1·d-1 and 22 g·kg-1·d-1(as MLSS), respectively. For nitrite oxidation, the favorable initial pH ranged from 7.5 to 8.0, under which a specific nitrate nitrogen (NO₃--N) producing rate of 35.6 g·kg-1·d-1(as MLSS) was obtained. It showed that the satisfactory ammonia oxidation and nitrite oxidation efficiency would be obtained by the enhancement of metabolic activity both of the nitrite and nitrate bacteria when the pH of wastewater was kept at about 8.0 in the nitrification process.

Abstract:To study the pollution characteristic and cancer risk of PAHs in water environment, water and sediment samples were concurrently collected on 13 monitoring sections within the Songhua River Basin. Totally, 6 batches of sampling programs were conducted from 2006 to 2010, including the low water season, the high water season and the icebound season. Water and sediment samples were extracted by liquid-liquid extraction and Soxhlet extraction, respectively. The qualification and quantification of PAHs were analyzed by GC-MS. The compositional pattern of PAHs indicated that low ring PAHs were predominant in water samples, while high ring PAHs dominated in sediment samples. The average total concentrations of 15 PAHs were (73.7±27.8)ng／L and (127±117)ng／g, ww for water and sediment samples, respectively. The concentration of PAHs was lower than those of other rivers in China. Obviously seasonal variation of PAHs concentration was observed in the water environment of the Songhua River. For water samples, the PAHs concentrations in the low water season and the high water season were higher than those in the icebound season. For sediment samples, the PAHs concentrations in the low water season were much higher than those in the high water season. The results of the incremental lifetime cancer risk assessment model indicated that the estimated integrated lifetime cancer risks were less than for 10-6, indicating low level of cancer risk for all age groups.

Abstract:Heterogeneous catalytic ozonation was applied to the treatment of coal chemical industry wastewater secondary effluent. Activated carbon-supported copper and manganese oxide were used as catalysts to assist ozone in degrading COD and NH₃-N of secondary effluent. The results indicated that the presence of catalysts significantly elevated the removal efficiency of ozone on COD and NH₃-N, as compared to the single ozone oxidation. The final effluent removal efficiency of COD and NH₃-N were 60％-72％ and 30％-35％ respectively, the average concentration of COD and NH₃-N was lower than 60 and 15 mg／L, and met Wastewater Discharge Standard (GB 18918—2002). The catalytic activity was restricted in acidic conditions and promoted in alkali conditions, however, catalysts improved degradation efficiency regardless of acid-base conditions as compared to the single ozone oxidation. The final effluent biodegradability was significantly improved, and no secondary pollution in the receiving water was produced.

Abstract:To get an effective electric desalination system, the electrosorption performance of a capactive deionization(CDI) and a membrane capactive deionization(MCDI) was compared. The electrosorption capacity and electrosorption rate of CDI and MCDI with different salt concentrations were studied when powdered activated carbon was used as the electrode material. The results showed that as the salt concentration increased from 0.05 to 0.5 g／L, the electrosorption capacity of MCDI increased dramatically from 99.4 to 694.4 mol／g, while the electrosorption capacity of CDI just increased from 80.3 to 135.7 μmol／g.

Abstract:To explore the indoor air pollution at rural houses in severe cold region in winter, a field study was conducted at 10 rural houses in two villages around Harbin. The indoor pollutants including PM2.5, PM₁₀, CO, CO₂, SO₂, NO_x, TVOC and NH₃ were tested and the correlation of pollutants were analyzed. The results showed that PM2.5, PM₁₀, SO₂, NO_x, CO₂ and CO were the main pollutants at rural houses in winter, with the overproof rates of 93％, 75％, 62％, 23％, 99％, 64％, respectively. There were good relations between PM₁₀ and PM2.5, CO and PM2.5, respectively. In addition, the linear correlations were also found between SO₂ and CO₂, NO_x and SO₂, respectively. The main test indices of pollutants were given based on the regression analysis results. The test method of pollutants was proposed at rural houses in severe cold region in winter.

Abstract:To study the factors that influence the test precision of percent air voids of asphalt mixture based on mesoscopic scale, German Phoenix v|tome|x S240 industrial X-ray CT was utilized in combination with orthogonal test and variance analysis to study how different CT parameters and gradation types influenced the 3D reconstruction volume parameters of asphalt mixture. Marshall specimens were scanned by changing the parameters of CT and gradation types of asphalt mixture and the results were used for three-dimensional analysis, the relation between influence factors and percent air voids was also built, and then determine the optimal scanning parameters. The test results showed that it is feasible to make three-dimensional volume analysis of asphalt mixture on the basis of meso-scale; the scanning parameters and gradation types have different levels of effects on reconstruction results; the test accuracy would be improved by increasing scaning voltage and current properly and as well as choosing the appropriate filters. The percent air voids that obtained on the base of both meso-scale and macro-scale had good correlation under the condition of appropriate parameter of apparatus,in addition can improve the accuracy and economy of the test.

Abstract:To study the effect of structure combinations on rutting resistance, firstly, dynamic modulus tests and single-layered wheel tracking tests were carried out to get basic parameters and anti-rutting resistance of seven asphalt mixtures designed. Secondly, double-layered structural wheel tracking tests subjected to heavy loads were conducted for three pavement structure combinations made up of asphalt mixtures utilized, and then compared the results with the single-layered ones. Finally, three-directional strain of pavement was got on site utilizing fiber Bragg grating (FBG) intelligent test technology, and the rutting resistance of actual asphalt pavement was evaluated through these results. Results show that rutting resistance of pavement structures cannot be reflected by single-layered wheel tracking test accurately, while the double-layered does. Additionally, modulus combinations with different layers must be taken into account in order to maximize the rutting resistance of asphalt mixtures.

Abstract:To note and proclaim the accuracy and stability of displacement input model and multiple support response spectrum(MSRS) when non-classical damping in bottom element is adopted, this paper involves in two aspects-theoretical derivation and calculation analysis. The difference of time-domain model between classical and non-classical damping in bottom element is discussed. On the basis of time-domain model, the formula of MSRS is given and deduced, and it is verified by a numerical example. The derivation and analysis show that the stiffness-related damping term in bottom element does not appear in the displacement input model, the displacement input model and MSRS do not have problems of non-convergence, and the accuracy and stability of the displacement input mode is verified.

Abstract:To investigate the influence of mainshock-aftershock sequences on displacement responses, failure mode, global damage evolution, etc of structures, the sequences are generated by combining the next generation attenuation (NGA) relationship for earthquakes with the relationship between main shock and strong aftershock. The modified section damage ratio model is applied to analyze additional damage of an example structure under strong aftershocks, as well as probabilistic accumulative damage. The investigation indicates that additional damage incurred by strong aftershocks tends to increase as their probabilities of exceedance (POE) decrease. Approximate negative correlation could be observed between the damage ratios of main shocks and those added by strong aftershocks. When structures experience substantial damage under main shocks, probabilistic accumulative damage of structures would change significantly even coupled with damage induced by low-level aftershocks. Additional damage would be aggravated by so-called analogous resonance phenomenon when the predominant periods of the response spectra of these aftershocks are close to the vibration periods of damaged structures under main shocks.

Abstract:To study static behavior of circular reinforced concrete silo strengthened with pre-stressed carbon fiber reinforced polymer (CFRP) under stored material load, considering the influence of reinforcement parameters such as strengthening method, pre-stress level, width, thickness, and reinforcement form on reinforced effect, comparative analysis were performed between reinforcement models established according to 5 different influencing factors. The results show that lateral pre-stress could effectively restrict radial displacement,concrete and steel stress of silo wall and improve the stress level of silo wall. The lateral pre-stress can largely improve the damage stress of CFRP and bringing the high-strength characteristic of CFRP into full play. The thickness of CFRP should be from 0.35 mm to 0.50 mm and the pre-stress level should be from 10 to 15 percent of its ultimate tension strength.

Abstract:In this paper, in order to solve the defects of sensors and distributed process for monitoring the stress of retard-bonded steel strand, according to characteristics of retard-bonded prestressed concrete and optical fiber sensing, novel self-monitoring retard-bonded smart steel strand was designed and manufactured. Then the FBG retard-bonded smart steel strand were applied to a retard-bonded prestressed one-way slab in a Hall, and the availability and reliability of the novel smart steel strands was verified. The results show that the retard-bonded smart steel strands have simple structure and definite mechanism. The mechanical properties of the smart steel strand are lower than ones of ordinary steel strand, and the smart strand has the ultimate tensile strength of about 88% of common strand, and the sensing properties (hysteresis, repeatability, linearity, and total accuracy) are less than 3%. It has been verified that the novel smart steel strand have the advantages of simple and easy construction process by the application in the practical project. And the robustness of the novel smart strand can meet the long-term monitoring for prestress losses in the practical engineering.

Abstract:To overcome the scope limitation of video observation from fixed platforms, a new method of detecting vehicular trajectory from the traffic flow video provided by model aircraft is proposed. First, model aircraft shoots the traffic flow in the air to get the video which is consequently extracted into continuous frames. Second, by using the pinhole camera model and the algorithm of space coordinate transformation, the coordinates of vehicles from the continuous frames are obtained to form the spatial temporal trajectory of vehicles. Finally, three kinds of bias of the proposed method are analyzed. The results show that the relative bias in the standard checkerboard testing is less than 5％, and the accuracy of the data collected by the system under the real road is greater than 90％. The proposed approach provides a large scope and low-cost way for traffic observation, which can meet the demand of survey in transportation engineering.

Abstract:To discuss the impact of the system properties on the public acceptability of congestion pricing and the relationship between public acceptability and effectiveness of it,five system properties of congestion pricing are selected as the model variables, and the ordered probit model and the MNL model are used to establish the models of public acceptability and effectiveness, which are calibrated by 476 sample data from SP survey, then the acceptability and effectiveness of three pricing scenarios are predicted by the two models. The research results reveal that the system properties influence acceptability greatly, but do not significantly influence effectiveness. At the disaggregate level, all charging schemes in this research are effective, and highly effective schemes are less acceptable, whereas much of highly acceptable schemes are still effective, which indicate that not all of the effective charging schemes are unacceptable. To enhance the feasibility of congestion pricing, the design of the measure should focus on the public acceptability of it.

Abstract:To make use of the latest measurement information sufficiency, and to improve the accuracy of attitude estimation, based on the analysis of the current iterated filtering strategy, an improved iterated cubature Kalman filter(IICKF) is presented in this paper by combining a new cubature points iterated strategy with cubature Kalman filter. The filtering algorithm uses the cubature numerical integration theory to calculate the mean and variance of the nonlinear function, utilizing the state augmented method to solve the issue that the state is correlated with the measurement noise in the iterated process. A new cubature points iterated strategy is developed, which can directly iterate the cubature points, and thus avoids to generate cubature points by calculating the mean-squared root. It overcomes the limitation that sampling points are produced by the Gauss approximation in the traditional iterative strategy, which can reduce computational complexity. Simulation results show that IICKF is superior to multiplicative extended Kalman filter and iterated cubature Kalman filter in precision, which indicates that it can help to improve the accuracy of attitude estimation.

Abstract:The paper aims to provide an approach to obtain a lower bound of H∞ control performance in state space. It is not involved in algebraic manipulation of Riccati equation and only concerned with the solution to the standard H₂ Riccati equation. As a consequence, the approach can help one to narrow the optimal H∞ performance search via bisection method to a smaller range and considerably reduce the search cost. In addition, the approach enables us to have an insight into not only the link and difference between the optimal performance and the H∞ performance including the optimal control and H∞ control performance, the optimal estimation and the H∞ estimation, but also the impact of the multiple-channel disturbances or previewable disturbance on the H∞control performance.