Abstract:To investigate the influences of concrete creep on the out-plane stability of concrete-filled steel tubular (CFST) arches, a numerical method was presented for the out-plane creep stability analysis. The method combined the age-adjusted effective modulus method (AEMM) for the creep analysis and the finite element method for the structural analysis. The time-dependent initial geometric imperfection was introduced to express the creep deformation of CFST arches at any time. Then the out-plane creep stable bearing capacity could be obtained via the finite element analysis. Based on the method, an existed experimental CFST arch model was taken as a basic researching object, and the influences of the loading levels, slenderness ratios, rise-to-span ratios, lateral loads, steel ratios and loading ages on the out-plane creep stable bearing capacity were discussed. The results show that the method is of good efficiency and applicability; the slenderness ratios, steel ratios and loading ages have great influences on the creep stability, while the rise-to-span ratios and lateral loads have little influence; the creep-induced decreased degree of out-plane creep stable bearing capacity could rise to 13.8％ which should be concerned in design.

Abstract:To study the properties and effects of high-amplitude ground motion, while modifying the design spectra, 60 records from 20 events satisfying at least one of the following requirements: PGA≥1 g, PGV≥100 cm／s or PGD≥100 cm, were collected and analyzed. The evaluation factors for ground motions’ damage potential related with the ground motions’ characteristics were summarized and the Factor Analysis Method was used to realize the simplification and integration. Explanation of new factors’ physical meanings was also discussed. Additionally, characteristic periods and the maximum amplification coefficients for the large-amplitude ground motions were calculated and compared with those adopted in current design codes. Suggestions on the modification of design spectra were indicated based on the possibility of potential hazard.

Abstract:To study the feasibility of partial nitritation of domestic sewage with low ammonia nitrogen, actual domestic sewage was treated by high rate bio-filter and up-flow biological aerated filter(UBAF). The effect of flow direction on the performance of high rate bio-filter removing COD and NH₄+-N and the effect of temperature and DO on the efficiency of UBAF for partial nitritation were researched. Results showed that at the hydraulic loading of 0.58 m³／(m²·h), COD volume loading of 2.30 kg／(m³·d), air-water ratio of 3.6∶1 and room temperature, up-flow filtration achieved high COD and low ammonia-nitrogen removals. Ammonia nitrogen removal rate reached 84.58％ and nitrite content in the effluent of UBAF achieved 23.01 mg／L on the conditions of temperature 30-33 ℃, DO 2.5-3.0 mg／L and pH value 7.8-8.1. Further study on the change of nitrogenous compounds in different depth combining with FISH demonstrates that a certain degree CANON process could exist at the end of UBAF. The two-stage reactor could domesticate decarbonizing and denitrifying bacterias independently, the partial nitritation of domestic sewage with low ammonia nitrogen can be achieved.

Abstract:To know the effects of combined disinfection on DBPs and enhance water quality safety, static pipe reactors were used and three kinds of commonly used pipe materials were selected to investigate the effects of pipe materials on chlorite formation in combined disinfection of chlorine and chlorine dioxide. Results indicated that the chlorite levels were the highest in PVC pipe and lower in metal pipes for both of the two kinds of combined disinfection. The difference between the two ways was that in the way of adding chlorine and chlorine dioxide together, chlorite levels in the ductile iron pipe increased with the increase of chlorine and decrease of chlorine dioxide in the mixed disinfectant. While, for the way of adding chlorine first and then adding chlorine dioxide, the chlorite levels were higher in ductile iron pipe than that in stainless steel from the beginning to the end.

Abstract:To analyze the growth characteristics and predation potential of tubificid worms as the predator for excess sludge, the variations in the growth, respiratory rate and sludge reduction efficiency of such worms under different pH value, temperature, carrier thickness and light intensity were investigated. The results showed that the worms could live in a pH range from 4 to 8, and therefore might have adaptability to the pH change in practical sewage sludge. The respiratory rate of worms reached the maximum at 25 ℃, indicating the higher biological activity at this temperature. The worm immobilization and performance for sludge reduction were improved by the carrier with 1 cm of thickness, where only 3.8％ of the total worms left. Natural light had no significant effect on the sludge predation by worms. But strong light was not recommended by which the escape and hiding behavior of worms had been caused. The optimal sludge reduction efficiency was above 27％.

Abstract:To optimize the fermentation parameter of Klebsiella. sp, orthogonal experiments were used to quantify the degree of the fermentation parameters of flocculant-producing bacteria MFX on the flocculation rate and the yield, which indentified temperature, shaking revolution and pH value as the input of neural network, flocculation rate and yield as the output of neural network, and then a training sample was designed. After repeat training, a prediction model with high accuracy and small error was established by which the optimum fermentation conditions: the temperature of 33 ℃, the stirring speed at 141 r／min and pH value of 7.90, were obtained. Meanwhile, the actual flocculation rate and the yields were 92.67％ and 2.180 9 g／L, respectively. The flocculation rate increased 4.08％, and the yields of bio-flocculant increased 14.36％, which improved the yield of bio-flocculant. The model was used to predict the fermentation process of flocculant-producing bacteria F+in the fermenter, the simulation error was small, which was the basis for the prediction and control of industrial fermentation process.

Abstract:To improve the visible light photocatalytic activity of TiO₂, in this study, TiO₂ nano-tubes arrays (TNTAs) were in-situ grown by anodization of Ti foils, and noble Pd nano-crystallites were electrochemical deposited onto the as-prepared TNTAs photoelectrode. The morphology, surface state and light absorption ability of the resulting electrodes were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and UV-visible light diffuse reflection spectroscopy (UV-vis DRS), respectively. It was found that Pd nano-crystallites were successfully decorated onto the surface of TNTAs electrode, and existed as the form of Pd⁰. In addition, the light absorption of Pd／TNTAs photoelectrode was greatly red-shifted to visible region. Furthermore, methyl blue (MB) was served as the probe molecules, and the effects of deposition voltage and time on the photocatalytic (PC) performance were mainly investigated. It was found that when the deposition voltage and time were -0.8 V and 10 min, respectively, the optimal photodegradation of MB could be obtained, which fitted well with the pseudo-first-order kinetics formula. Under the simulated sunlight irradiation within 120 min, the 71.4％ degradation rate of MB could be achieved, which was 1.5 times larger than that of bare TNTAs photoelectrode.

Abstract:To improve the photocatalytic efficiency of TiO₂ for amoxicillin removal, a series of precious metals catalysts (M／TiO₂, M=Ru, Rh, Pd, Ag, Ir, Pt or Au) were prepared by light deposition method. The synergistic photocatalytic activity of M／TiO₂ with KBrO₃ for degradation of amoxicillin (20 mg／L) in aqueous solution was researched under UV light (365 nm). The effects of metal loading, catalyst concentration, KBrO₃ concentration and pH on the photocatalytic activity of Rh／TiO₂ with KBrO₃ were explored. The results show that the photocatalytic activity of M／TiO₂ is closely related to its work function and KBrO_3has a greatly synergistic role on M／TiO₂. Under the conditions of 0.1％ Rh loading, Rh／TiO₂ concentration of 0.15 g／L, KBrO₃ concentration of 0.5 mmol／L and reaction liquid pH value at 5, the amoxicillin can be degradated completely within 90 min. Furthermore, the results of kinetic study show that the degradation reaction can be expressed by the first-order reaction kinetic model.

Abstract:To removal the raw materials of bisphenol A (such as phenol, acetone, and molecules of bisphenol A dissolved in the acetone) and various phenolic compounds, which are hard to be detected, from bisphenol A producing wastewater, the adaptability and treating efficiency of microorganisms to this type of wastewater are tested by static cultivating and acclimating the anaerobic granular sludge. The results of static adaptability tests show that the microorganisms adapt to this type of wastewater well. The COD is decreased by 58％ when the contact time is 6 hours. After acclimating the microorganisms for 60 days, the COD removal efficiency can get to 50％ with hydraulic retention time of 9 hours. Great diversity of microorganisms both inside and on the surface of the granular sludge can be found when using SEM to observe the granular sludge in the reactor before and after the experiment.

Abstract:The preparation was optimized for the quantitative and qualitative determination of six fluoroquinolone antibiotics(FQs) in muscles of aquatic products using ultra-performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UPLC-MS／MS). Types of extraction, content of formic acid in extraction solution, styles of the cleanup, and amount of dehydrates were discussed for the purpose of reaching the optimal result of sample preparation. Extraction of the FQs was carried out with acid acetonitrile and defatted with n-hexane, while the water in the muscle was removed by sodium sulfate. Separation of the FQs was achieved by using a BEH C18 column under gradient elution at flow rate of 0.20 mL／min with the mobile phases being composed of 0.1％ formic acid solution and acetonitrile. The mass spectrometer was operated in positive ion mode using electrospray ionization in the multiple reaction monitoring (MRM) mode. The standard curves were linear (R²≥0.998) over the concentration ranging from 1.0 to 1 000 μg／L when the limit of detection (LOD) and limit of quantification (LOQ) were 0.1 and 0.2 μg／kg, respectively. Recoveries of the FQs in spiked samples(fish, shrimp and crab) arranging from 2 to 100 μg／kg were between 76.9% and 95.9％ with the relative standard deviation between 4.8％ and 9.2％.

Abstract:A finite element model combined with bridge deck pavement structural style is established to analyze mechanical properties and influence factors of bridge deck pavement structure. The effect of different levels braking force coefficients, top and bottom layer material modulus combination of bridge deck pavement, deck pavement thickness variation are analyzed.Results show that different horizontal loads have little effect on principal stress but much effect on shear stress inside the pavement layer. With the increase of horizontal load, the maximum shear stresses inside pavement layer and waterproof adhesive layer increase linearly.Principal stress inside the pavement layer changes little, while shear stress between layers decreases in a small amplitude with the increase of combination modulus of pavement layer.Increase of the thickness of pavement layer has little effect on principal stress and maximum shear stress between layers decreases with increase of thickness.Conclusions obtained by this paper can be used to provide theoretical reference for material selection and structure design of bridge deck pavement.

Abstract:First, the analytic expressions of fundamental wave and each order of harmonic wave for the output voltage is calculated by the Fourier decomposition method, which is used to analyze the modulation ratio of the three-phase inverter modulated by wavelet modulation. Then, the equation of the voltage modulation ratio (M) is derived and the scope of M is obtained by calculation, giving the range of the linear modulation for the three-phase inverter under the wavelet modulation. Finally, the correctness and rationality of the theoretical analysis is validated by computer simulation. The research result shows that the output voltage quality under the wavelet modulation is better than that under SPWM and SVPWM when the switch frequency is equal to the modulation ratio. In addition, the range of linear modulation under wavelet modulation is larger than that under SPWM and SVPWM.

Abstract:In order to study the interfacial reaction of carbon fiber surface coating in the process of preparing composite materials, an experimental method based on dynamics was adopted. Different DSC curve will be obtained from the reaction enthalpy measurement of resin and curing agent, resin and sizing agent, sizing agent and curing agent and so on with different heating rate. The pre-exponential factor A, reaction order n and apparent activation energy E and dynamics equations were calculated by the Kissinger, Flynn-Wall-Ozawa and Crane methods. The activation energy of the sizing agent and curing agent is 47.25 kJ／mol, while the activation energy of the resin and curing agent system is 49.64 kJ／mol. It can be concluded that the carbon fiber surface coating reacts with curing agent first than the resin.

Abstract:To investigate the overall buckling behavior of Q420 high strength welded gavalized steel tubes, an axial compression column test was conducted, the buckling modes and ultimate strength were analyzed, and the buckling strength of the specimens were calculated, which were compared with the column curves in the Chinese code. It shows that the stability factor φ calculated from test results is much higher than that calculated according to the Chinese code. At the same time, the comparison of axial compressive test result between galvanized round tubes and the ungalvanized ones is introduced, and the results show that the hot galvanizing processing improves the bearing capacity.

Abstract:To more clearly elaborate the influence of water-cement ratio (w／c) on hydrate process of Portland cement, the kinetic model (Tomosawa model, T model) of hydration was analyzed and simplified. In simplified T model, the hydration process was controlled by mass transfer, interfacial reaction and diffusion process at different stages, respectively. Based upon the degree of hydration measured by chemical bound water method, T model and simplified T model were applied to investigate the relationship between the degree of reaction and hydration rate for cement pastes with different water-cement ratios. The results show that the effects of w／c on the parameters in the T model are different. Along with the change in w／c, the coefficients of mass transfer are almost unaffected, the interfacial reaction coefficient is less affected, while the diffusion coefficient is significantly affected. The development trend of hydration rate with degree of reaction at different stages can be well simulated by simplified T model, which is not affected by w／c. However, the critical degree of hydration from interfacial reaction to diffusion process is increased with the increasing of w／c.

Abstract:There may be some obvious error in long-span isolated structures' seismic responses calculated by multi-point earthquake calculation models. In this paper error reason and corresponding solution methods are given. Firstly, several main calculation models for seismic analysis of long-span isolated structures under multi-point earthquake excitations are described, and their mechanisms and features are also explained by rigorous theoretical derivation. Then, theoretical defects and error of displacement model are especially pointed out, which would lead to wrong results if arbitrarily utilized in long-span isolated structures. Furthermore, some modification and theoretical basis are given. Finally, a multiple degrees of freedom simple model and a real long-span space truss structure of hangar are given as numerical example, and viewpoints and suggestions in this paper are verified. The displacement mode inherent in SAP2000 software is applicable in seismic response calculation of structure under multi-point earthquake excitations.

Abstract:To study the impulse wave effect of high-rise buildings under vertical earthquake near fault region, simplified wave propagation method is adopted. In elastic range, typical structural system is simplified as one and two dimensional model, and reflection and transmission coefficients of longitudinal wave through lumped mass are determined. Structural vertical seismic macro response is calculated by simplified wave propagation method in which difference time delay and FFT filter are used. The analysis shows that, compared with the vibration method, the wave propagation method is more targeted in calculating structural vertical seismic response, especially under impulse-type vertical earthquake. The axial force fluctuation and relative movement caused by vertical earthquake can not be ignored.

Abstract:In order to describe capacity of intersections, and take the factors such as intersection geometric feature, traffic flow characteristic, channelized section and regulation measures into account, this research exprersses the basic phase set based on graph theory through the analysis of conflict movements. Then the common expression of capacity is gven by equations. The four-leg intersection is analyzed as an example, whose necessary and sufficient condition is derived. At last, the optimization model of intersection capacity is established. The results show that the signal parameters greatly influence the intersection capacity. Equivalent saturation degree assignment is actually intersection capacity maximal control. For common four-leg intersection, the sufficient and necessary condition for capacity is that the sum of flow ratio equals 2.

Abstract:To ensure the safety of water in the process of translation in long distance raw water diversion pipe, the damagemant and recovery of purification by added chlorine to Biofilms Annular Reactor(BAR) which simulated the pipe was investigated. The results showed that the prechlorination can damage the pipe bioflim, lower the removal rate of NH₄+-N, NO₂--N, CODMn, TP, and the effluent of concentration of CODMnand TP was elevated in short term and NO₂--N concentration was rised in long term after prechlorination. The effluent concentration of NO₂--N can be reached 7 times of the influent. The recovery of removal of NH₄+-N was earlier 2 days than that of NO₂--N, and NH₄+-N and NO₂--N could be completely repaired on 8 dsys and 10 days, respectively. The removal of CODMn and TP can be completely repaired on 8 days.

Abstract:A new three-step method called stereoscopic intersection extraction based on footprint graph model is proposed in this paper. Firstly, the primitives are extracted by footprint, then the road model is built based on the graph of primitives, finally, the road lamination is realized by referring and reasoning. Though the footprint algorithm presented by Hu can be used to extract road primitives, there exist two problems, one is that two toes which are adjacent can be easily considered as one toe, and the other is that troughs are not likely to be detected, we solved these two problems by making some improvements. Then we use stereoscopic inferring algorithm to link the roads, set the heights of the roads and realize lamination. At last, we experiment on the dataset of Google earth, as a result, this algorithm can reflect the levels of the roads effectively, what’s more, the correctness being guaranteed, this algorithm still has strong robustness.

Abstract:To engineering analysis and application,based on velocity potential theory, the liquid movement potential function and the expression of base shear, overturning moment were established. The floating roof was simplified as a rigid, homogeneous plate. Starting with plate vibration equation and boundary conditions of the plate-liquid surface interaction, the sloshing analysis equation and the wave height expression were constructed. A simplified analysis mechanical model was established by adopting base shear equivalent and the same way to acting energy, and the system motion equation was given according to the energy principle, given the impact of the relevant parameter. Selected 50 000 m³ storage tank, the response spectrum and time history analysis were contrasted. The results showed that: base shear force, bending moment and wave height were close to related research literature and finite element solution,the research result is feasible, it could meet the engineering design needs.

Abstract:Aiming at the parameter identification of Stewart platform, a parameters identification method based on error sensitivity analysis was presented. With the creation of the position and pose error model at two different points of move platform, the identification method for structural parameters of Stewart platform is deduced. The method explains the sensitivity between the structural parameters and the position and pose of Stewart platform at the different points. In an instance, Stewart platform position error is reduced from 4.8 mm to 1.12 mm, and angle error from 5.4° to 1.05°. Therefore, the identification method is verified effective and feasible.