Abstract:To promote engineering application of reactive powder concrete, relative research literatures published are summarized and studied. The method of classifying strength grade of reactive powder concrete is proposed according to characteristic value of 70.7 mm side length cube compressive strength. Reactive powder concrete mechanical property indexes on size effect of compressive strength, axial compressive strength, axial tensile strength, elastic modulus, peek compressive strain and ultimate compressive strain are analyzed, and the conversion relation of these mechanical property indexes are obtained. The material partial factor of reactive powder concrete is calculated based on first-order second-moment theory.

Abstract:To study the hysteretic performance and lectotype suggestion of the thin steel plate shear walls with four-side connections, two-side connections and silts, the hysteretic performance of those thin steel plate shear walls were systematically investigated utilizing the ANSYS software package. Comparisons of the initial stiffness, peak load, ductility and energy dissipation capacity of those steel plate shear walls were carried out base on the numerical results. Results showed that those three types of steel plate shear walls had proper ductility and energy dissipation capacity. The hysteretic curves of the thin steel plate shear walls with four-side connections and two-side connections had pinch phenomenon, while their initial stiffness and peak load were relatively high. They could be used in the multistory steel structure residences in high intensive seismic region or high-rise steel structure residences. The hysteretic curves of the thin steel plate shear walls with silts exhibited plump loops, but its initial stiffness and peak load were low. This kind of shear walls could be applied on the multistory steel structure residences in low intensive seismic region or low-rise steel structure residences.

Abstract:Aiming at providing new method and reference for the construction of near-fault design spectra, characteristics of bi-normalized combined spectra of 53 typical near-fault directivity effect ground motions are analyzed by considering the influence of site condition. Results show that the bi-normalized combined spectrum exhibits the highest correlation with the amplitudes of ground motions, and the lowest statistical variability, compared with those of acceleration spectrum, velocity spectrum and displacement spectrum. Finally, site-depended design spectral models for near-fault region are suggested based on features of bi-normalized combined response spectra.

Abstract:To investigate the damage and deformation mechanism of large scale steel floating roof oil tank under the combustible gas explosion, according to the Von Mises yield condition and strength theory, the generalized yield function and failure criterion of tank wall under blast loading is established. A finite element model of 15×10⁴ m³ floating roof tanks has been established by explicit package ANSYS／LS-DYNA, and the dynamic responding processes such as displacements, acceleration, stress and strain of the tank walls structures under blast loading have been simulated. The results show that the failure mode of the floating roof tank is collapse and buckling on top of the impact surface tank walls. The yield range first appears at the stagnation area and then propagates to the neighboring parts, and the irregular plastic hinge circle obviously appears around the deformation area, which results in the concaved bucking of the tank inner surface. During the whole process, the inner liquid not only impacts on the structures, but also absorbs and consumes part of the blast energy.

Abstract:The flow velocities and pipe materials may be variable in drinking water distribution system, and their interaction on the water quality and biofilm formation under a certain chlorine level have been investigated. Heterotrophic plate counts and denaturing gradient gel electrophoresis were employed to analyze biofilm formation, and the results showed that the chlorine, TOC of bulk water, total bacteria counts and microbial community structure were all varied in pipe materials, while flow velocities only affected the chlorine of bulk water and biofilm biomass. In the same time, PE pipes attached significantly greater biofilm biomass than stainless steel. The biofilm biomass grown under flow velocities 0.2 and 0.4 m／s were significantly greater than that under 0.8 m／s, but the biofilm growth between 0.2 and 0.4 m／s were not significant. In the mature biofilm microbial community, Sphingomonas sp. and Bacillus sp. were dominant in all biofilms, while the hydrophobic bacteria were difficult to grow on the stainless steel pipe, especially under high flow velocities.

Abstract:To monitor the pressure distribution in urban water distribution system (WDS), a method of locating pressure monitoring points is proposed based on district model of WDS. First, Euclidean distance is introduced to measure the pressure fluctuation similarity between two nodes within a running cycle. Whether a node in a pipe is classified as one sub-district depends on that the Euclidean distance values between the node and other nodes of this sub-district is within a given maximum allowable Euclidean distance. Finally, a node with minimum average Euclidean distance in a sub-district is chosen as its pressure monitoring point location. This district method is applied to monitoring point layout of a practical WDS. The analysis results show that different district solutions are obtained by changing the maximum allowable Euclidean distance. All the nodes in each sub-district are connected and the Euclidean distance between any two nodes is within a given maximum allowable value. After placing one pressure monitoring point in each sub-district, the results show that the pressure distribution in WDS can be effectively reflected, when average relative error is 4.53％ and the number of pressure monitoring point is four.

Abstract:To analyze the effect of sludge fermentation liquid, using as internal carbon source, on microbial community structure in anaerobic-anoxic-aerobic process, three-month-long operational experiment was conducted at flow ratio of fermentation liquid and domestic wastewater 1∶35 at room temperature. The clustering analysis indicated that the microbial community structure was changed significantly by fermentation liquid, and the microbes of 5-30 d and 45-90 d had quite different homology. The microbial diversity analysis demonstrated that the Shannon-Wiener index increased from 2.6 to 3.1, resulting in the enhancement of operational stability. Meanwhile, fermentation liquid appeared to be selective for ammonia-oxidizing bacteria Nitrosomonas sp., nitrifying bacteria Betaproteobacteria and Nitrospira sp., denitrifying bacteria Comamonas sp. and phosphorus-accumulating bacteria Gammaproteobacteria, which led to the TN and TP removal efficiency improved from 64.5％ and 52.4％ to 84.7％ and 94.3％, respectively.

Abstract:To achieve the water standard of low-permeability reinjection for secondary oil wastewater treatment, this experiment took the oil-field wastewater as the processing object, and an experimental device which took plate ceramic membranes as the core processing unit in the production site was set up. The study mainly focused on the effects of the membrane flux, reaction temperature and aeration rate on treatment by monitoring the changes in transmembrane pressure difference. On the premise of normal operation of the experimental device, the optimum membrane, reaction temperature flux and aeration rate was set as 22.5 L／(m²·h), 50 ℃ and 1 L／min, respectively. Filtration performance of membrane could be better recovered after immersing the membrane in 0.05 mol／L HCl or HNO₃ solution for 12 h, and membrane flux recovery rate reached above 96％. As the results show, oil content and SS of effluenttreated by plate ceramic membrane are less than 1 mg／L, and all indexes of injection water are better than the A1 class standards in SY5329—94. It demonstrates that plate ceramic membranes can replace traditional steps in the oily wastewater treatment, such as flotation, rough filtration and fine filtration.

Abstract:By comparative studies on BAF between CaCO₃-biofilter media which is a new-style filter material made of grain-slag and ceramisite filter material, the performance of phosphorus removal was discussed at different HRT and phosphorus concentrations. The results indicated that compared with ceramisite filter material, CaCO₃-biofilter media had a higher removal rate of phosphorus in BAF. Under the condition of water temperature of 20-25 ℃, ammonia nitrogen load rates of 0.76-0.78 kg·(m³·d)-1and organic load rates of 3.55-3.62 kg·(m³·d)-1, the phosphorus removals of CaCO₃-biofilter media biological aerated filter with HRT 5,3 and 1 h were in the range of 65.20％-71.07％, 40.49％-48.02％ and 26.10％-33.11％ respectively. It was evidenced that CaCO₃-biofilter media biological aerated filter could remove phosphorus effectively by biologically-induced chemical precipitation and the settling matters had no effect on the effluent turbidity.

Abstract:Metal-graphene system was taken as the research object. Density functional theory (DFT), combined with local density approximation (LDA) and PWC functional, was employed to study the changes in the geometry structure, energy, charge distribution and density of states (DOS) of the systems before and after absorption of CO₂ on them. The results show that the electrons are transferred from the M-graphene system to CO₂, which is eventually activated by negative charge. The Cu-G system is most effective to activate CO₂ in these three complexes. The bond length of CO₂ increases by 6 and 14 pm, respectively, and the bond angle of O—C—O decreases to 122°. Furthermore, the first ionization energy and electron affinity of metal clusters and graphene play a decisive role in the electron transfer. Compared with the first ionization energy of graphene, the larger the electron affinity of metal clusters, the more the electrons transferred from graphene to metal cluster.

Abstract:To investigate the effect of positive-electrode grid on the failure of valve-regulated lead acid (VRLA) battery, the electrochemical behavior of positive-electrode grid for VRLA battery in the different density sulfuric acid electrolyte is studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Tafel curves, respectively. The result shows that the peak potential of oxidation and reduction peaks move to positive direction with the decrease of sulfuric acid density, indicating that lead can difficultly convert into lead sulfate, but lead sulfate easily convert into lead. The peak current increases with the decrease of sulfuric acid density, revealing that the lower sulfuric acid density is, the faster rate of conversion is. The acid density affects the conductivity of positive grid corrosion film, and the conductivity of positive grid corrosion film is good when the sulfuric acid density is about 1.30 g·cm-3. It is beneficial to improve the conductivity of grid corrosion film by decreasing the acid concentration.

Abstract:To explore the molecular genetic mechanisms of cytoplasmic male sterility in sugar beet, the differential proteins between the CMS line and its maintainer line were studied. Immobilized pH gradient two-dimensional gel electrophoresis (2-DE) technique and MALDI-TOF-MS were used to identify differentially expressed proteins in the three pollen development stages(stamen primordium differentiation stage, metaphase and uninucleate stage) between the Owen sugar beet male-sterile line(DY5-CMS)and its maintainer line(DY5-O). Six distinct proteins were identified in the stamen primordium differentiation stage and four distinct proteins were identified in the metaphase. In addition, all those proteins were related to the energy and respiratory metabolism. It was inferred that cytoplasmic male sterility of sugar beet might take place at the prophase of pollen development(contain stamen primordium differentiation stage and metaphase). The over-expression of energy and respiratory metabolism related proteins leads to metabolism disorder. Six distinct proteins are identified in the uninucleate stage of pollen development, and most of the proteins are related to photosynthesis of plants. It is speculated that the male sterility trait has formed at the late stages of pollen development and male sterility leads to the decreasing of photosynthetic.

Abstract:An improved hyperbolic model of load-transfer for the pile-soil interface under deep excavation conditions was developed. It not only considered the influence on the initial shear stiffness because of excavation which decrease the normal stress of the surrounding soil, but also considered the influence of excavation depth, width and length of pile. A full-scale numerical experiment was completed on a single pile in sandy soil after excavation and the bearing capacity of pile foundation was analyzed using this model, and then the results was compared with the measurement and the calculating values, which were calculated from the traditional model. It was shown that the ultimate bearing capacity of pile foundation after excavation, which was calculated from both model, are closed to measurement. The tip resistance and shaft friction on the bottom of pile calculating from traditional model which cannot consider the contribution of soil for the pile tip behind the supporting structure, however, have significant differences compared with the measurement. So, the improved model is better to estimate the shaft friction and tip resistance for the pile foundation after excavation.

Abstract:A special splitting test method has been introduced for PHC300 (prestress high concrete) pipe pile to research the characteristics of crack development due to the toroidal pressure. This crack generation method is considered to be the most negative situation for PHC300 pipe pile since the crack around steels can often be observed. The results show that crack depth increases with crack width in outer surface of PHC. The crack runs through the wall thickness of PHC as the measured crack width reach to 0.18 mm in outer concrete surface and 0.1 mm in inner surface, respectively. This is probably due to the crack extensibility, i.e., inner surface has a better extensibility than outer surface because cement paste layer and mortar layer tend to integral fracture in inner surface. Compared with a solid concrete structure, the crack in PHC is seemly difficult to recovery due to a relatively small bonding area in outer concrete surface contributed by the hollow structure. Crack recovery values increase with the increase of crack widths in outer surface, while crack recovery rates is opposite. The recovery rates of crack open displacement (COD) in outer surface are generally below 50％.

Abstract:To investigate the impact of different sustained load ratios (the ratio of sustained eccentric compressive load to ultimate eccentric compressive load) and different environments on hysteretic behavior and chloride mass fraction of RC(reinforced concrete) columns, the working conditions of RC structures in coastal region were simulated in laboratory. The sustained load ratios were 0,0.2 and 0.35, respectively. After the RC columns with sustained load had undergone 100 cycles of seawater dry-wet or 100 days in atmospheric environment, low cyclic horizontal loading test was conducted and chloride mass fraction in tensile concrete was tested. Results show that sustained eccentric compressive load lead to the apparent asymmetric pattern of the hysteretic curves of RC columns in seawater dry-wet environment or in atmospheric environment. And the asymmetric pattern of former is more apparent than that of latter. While the stress distribution of cross-section under horizontal cyclic loading is the same as that of sustained eccentric compressive load and the sustained load ratio is 0.35, the peak load and the energy dissipation of RC columns in seawater dry-wet environment are 0.89 and 0.57 times of that in atmospheric environment, respectively. But the former are 1.04 and 1.08 times of the latter if reverse cyclic load is applied. In the depth of 20 mm and 40 mm from tensile surface, chloride mass fraction of tensile concrete in the columns subjected the coupled actions of sustained load and seawater dry-wet cycles are more than 3 times of that only subjected to sustained load (the RC columns in atmospheric environment). These clearly imply that the coupled action of sustained eccentric compressive load and seawater dry-wet cycles could facilitate the chloride penetration and hysteretic behavior degradation.

Abstract:Earthquake source parameters have important impact on the near-fault ground motions and their spatial distribution characteristics. Using a discrete wavenumber finite element method, we simulate the ground motion fields, and then study the effect of fault depth on ground motion amplitude, spectra and duration from the directivity point of view. Numerical results show that: with increasing fault depths, the amplitude decreases but the difference between forward and backward direction still exists; the significantly affected areas is getting closer to the fault; and the radiation angle of directivity effect gradually extends to both sides of the fault strike. This phenomenon indicates that the source depth not only affect the amplitude of ground motion but also the significantly affected areas and locations. Therefore, the source depth parameter should be considered in the prediction of ground motion in engineering, especially in near-fault region.

Abstract:To clear the influence rule that the spatial pattern process of thermal comfort degree affected by urban heat island, and to provide theoretical support to the reasonable layout of city space, this paper constructed the criteria for the classification of thermal comfort degree affected by surface heat island effect, adopted the same phase of TM remote sensing data and ground measured data at the same time based on human comfort and human physiological reaction for the environment temperature. Utilizing the landscape pattern index evaluation method, this paper analyzed the urban heat island effect in downtown Tianjin from 1992 to 2011. The results show that, first, the space area is expanding of the thermal comfort degree affected, and the impact intensity is rising; second, for the secondary thermal comfort degree affected regions, the largest patch area is decreasing, but the total area is increasing; third, for the third and fourth thermal comfort degree affected regions which cause people feel discomfortable, patch classes area, the largest patch area, patch density are rising, indicating the heat island effect on the thermal comfort in the continuing deterioration; fourth, the fragmentation of heat island landscape patch, the mixture of patch types, the reduction of connectivity among strong heat island areas can weaken the impact of the urban heat island effect on thermal comfort; fifth, although saving land, high-rise residential building will increase the total area of deteriorating thermal comfort and make the local thermal comfort affected by super grade.

Abstract:Study on formation process of biological purification efficiency in raw water delivery pipelines was beneficial to improve water quality in long distance raw water delivery pipes. Using simulated pipeline reactors to simulate water situation in raw water delivery pipelines, and water samples were prepared in laboratory. The influent and effluent water quality, the microorganisms in the biofilm is continuously monitored. Results show that the ammonia nitrogen (NH₄+-N) and organic matter removal are stabilized after a gradual increase in first, and stable value decreases slightly compared to the maximum in the formation process of biological purification efficiency. Biofilm grow on polyethylene slides in simulated pipeline reactor and then harvest within 45 days, the removal rate of NH₄+-N remains stable at 75％. Nitrite nitrogen (NO₂--N) effluent concentration remains stable at 0.02 mg／L. Ammonia oxidizing bacteria (AOB) is dominant strain compared to nitrite oxidizing bacteria (NOB) in raw water delivery pipes. Removal rate of UV₂₅₄ and turbidity are about 30％, and orthophosphate (PO₄3-) removal rate ranges from 13.64％ to 38.78％.

Abstract:To cope with the controller design problem that the control input of single-input single-output (SISO) nonaffine nonlinear system is with an unknown dead-zone character, a controller design strategy based on fuzzy adaptive technique is proposed. Within this scheme, the unknown dead-zone is treated as a combination of a linear and a bounded disturbance-like term. For the case that the system states are measurable, an indirect adaptive fuzzy controller is constructed by using fuzzy logic systems and adaptive laws are given out according to the information of tracking error. On basis of the above controller design method, another indirect adaptive fuzzy output-feedback controller for immeasurable system states is designed based on the estimated states which are generated by an error observer. The theoretic prove process indicates that the two controllers can guarantee that the tracking errors converge to a small neighbourhood of the origin and all signals in closed-loop system are bounded. Simulation results demonstrate that the constructed controllers can make the system achieve the tracking control objective.

Abstract:In order to improve tracking performance of the approach, a new adaptive tracking algorithm of group maneuvering targets was presented. In the estimation of group centroid kinematic state, the deviation between the prediction value and estimation value of centroid speed was used to adjust the covariance matrix of process noise based on modified current statistical model, and a fading factor of strong tracking filter was used to adjust the state-estimation error covariance adaptively. In the estimation of group extension state, the prediction parameter of extension was calculated by using a fuzzy reasoning method, which had taken the deviation between the prediction value and estimation value of the corresponding elliptical area and the change ratio of deviation as the input of the fuzzy controller. Lastly, a method to judge split-off maneuvering of group targets was offered. Simulation results show that, compared with the existing methods, the proposed algorithm can obtain a better adaptive tracking performance in maneuvering scenarios, and detect the split-off maneuvering effectively.

Abstract:The method by using distilled water to replace organic solvents to dissolve PEO is simple and the air pollution caused by organic solvents volatilizing will be avoided. The PEO-LiClO₄-SiO₂ polymer electrolyte is prepared by solution-casting method, in which the water is as solvent, the nanometer SiO_2is inorganic filler and the lithium salt is LiClO₄. The effect of nano SiO₂ particles is analyzed. The micro-morphology, crystal structure and electrochemical properties of the electrolyte are characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and electrochemical impedance spectra (EIS). The results show that the crystallinity of PEO polymer electrolyte is decreased and the tensile intensity is increased when nanometer SiO_2particles are doped in the polymer electrolyte. The electrochemical stability window is 4.8 V, the highest ionic conductivities (25 ℃) of PEO-LiClO₄-SiO₂(6％) polymer electrolyte is 3.95×10-5S·cm-1and the ionic transference number is 0.29.