Abstract:To investigate the damage level of relative buildings after strong earthquake occurred in Wenchuan, Sichuan province in May 12th 2008, and propose the rational method for strengthening the damaged structures, the damage of buildings was surveyed. Different damages were found in the buildings in the relative regions. Damage types of reinforced concrete buildings mainly included collapse of columns, failure of joints, strong beams and weak columns, failure of infilled wall and partition. Shearing failure was found in the masonry buildings and masonry buildings with reinforced concrete frames on the ground floors. Based on the analysis of damages of these buildings, an idea of retrofitting the damaged building is proposed, i.e., strengthening the damaged members or joints, enhancing the seismic capacity of vulnerability members, and improving the robustness of the structures. According to this idea, the design and construction for more than 200 damaged buildings were conducted.

Abstract:There is a cooling tower located in the Golmud Salt Lake area, and due to the erosion of the acid gas and the alternate heating and cooling climate in the winter, it is seriously damaged. In order to grasp the damage situation of the cooling tower, the on-site test of the tower on the falling-off of the concrete, the distribution and propagation of the cracks and the concrete strength has been performed. Based on the test result, the internal force of the tower has been calculated with the application of the ABAQUS software, and the safety of the tower has been analyzed with the ratio of the ratio of the tower internal force and the resistance. According to the analytical result, the strengthening scheme has been proposed, namely, adding concrete layer to the outside surface and mortar layer to the inside surface of the tower, and coating the mortar layer with impervious material. Moreover, the calculation methods of the equivalent elastic modulus and the equivalent strength in verifying the bearing capacity after strengthening have been introduced in the paper, which provides reference to the damage evaluation and strengthening design for engineering projects of the same kind.

Abstract:To relocate the spancrete slab factory in Harbin, the major structural members retrofitted have been removed to a new factory. All of members including the columns, crane beam, precast beam, vertical and horizontal braces are used in new factory after detecting and identifying. The columns were increased 1.8 m by plant rebar and enlarging cross-section, and erected in new isolated footings. Other members, such as, crane beams, roof beams and braces were connected with columns. The double Tee slabs with and without rectangular holes were arranged by regular intermission on the roof beams. The safety and economy may be insured after forming the bent frames, meanwhile, the day lighting is improved.

Abstract:In order to enhance the Fenton oxidation of 2,4,6-trichlorophenol, copper ion was introduced to the Fenton reaction. The results show that, differing from ferrous ion, the copper ion exhibits no capability to decompose hydrogen peroxide to degrade the organic substrates; however, it can accelerate the degradation rate of 2,4,6-trichlorophenol by Fenton reaction, enhance the decomposition of hydrogen peroxide, increase the removal efficiency of TOC and release of chloride ion. Even lower copper ion dosage have significant enhancement on the degradation. The result of complete inhibition of the reaction by methanol and tert-Butanol suggests that hydroxyl radical is the most important reactive species in the Cu2+ enhanced Fenton reaction.

Abstract:Considering the competition of carbon source and sludge age contradictions of sludge age among the various functional bacteria in traditional A²／O process, parallel of anaerobic／anoxic+oxic process controlled by multi-point cycle was introduced. The relevant relationships between return sludge ratio of anaerobic／oxic and release／absorption of phosphorus and its impact on the treatment effect were analyzed, the influence of internal recycle ratio on nitrogen removal was also studied. Moreover, the distribution of the nutrients between anaerobic and anoxic with its impact on the treatment effect was researched, then the optimum parameters of the process was finally found. After calculating the solid retention time under the best conditions of process, physiological characteristics of various functional bacteria were investigated by PCR-DGGE and 16SrRNA sequence. The results showed that the optimum parameters of the process as following, the anaerobic sludge recycle ratio was 15%, aerobic sludge recycle ratio was 30%, nitrification liquid recycle ratio was 300%, anaerobic/anoxic influent ratio was 1∶1. With the optimum parameters, the removal rates of COD and ammonia were 92.27% and 97.54%, the removal rates of TN and TP were 87.52% and 96.66%. Nitrogen and phosphorus removal was better than the A²/O process. The parallel of anaerobic／anoxic+oxic process controlled by multi-point cycle could solve the problems of the competition of carbon source and contradictions of sludge age among the various functional bacteria efficiently.

Abstract:To solve the pollution of bisphenol A (BPA) which was considered as an environmental endocrine, boron-doped diamond (BDD) electrodes were prepared by direct current plasma chemical vapor deposition (DC-PCVD) system. Mechanisms and reaction pathways of electrochemical degradation of bisphenol A (BPA) at BDD electrode was investigated by high performance liquid chromatography(HPLC) and liquid chromatography-mass spectrometer(LC-MS). The results showed that BPA with different initial concentrations were completely mineralized to CO₂ at BDD electrode, following the pseudo-first-order rate kinetics. The apparent reaction rate constant for BPA with initial concentrations of 100 and 10 mg·L-1 were 0.494 and 0.700 h-1, respectively. When the current density was increased from 10 to 40 mA·cm-2, the apparent reaction rate constant and the removal rate were increased by 50.61％ and 11.26％, respectively. Seven intermediate products were detected in the degradation process, and two different degradation pathways were discovered. One pathway was that BPA was decomposed readily into one-ring aromatic compounds first and eventually mineralized by electrolysis to CO₂, another was that both of the aromatic rings in BPA molecular structure underwent ring breakage simultaneously and then continuously oxidized to CO₂ till the end of the reaction.

Abstract:In order to implement the bioremediation on the phthalate contaminated soil, seven bacteria strains D1-D7, which can use phthalate mixtures as the sole source of carbon and energy, were isolated from constructed wetland soil. The morphological, physiological and biochemical characteristics of the strains were studied. Strains D1 and D2 were identified as Pseudomonas sp., strain D3 as Enterobacter sp., the others as Rhodococcus sp., based on the 16S rRNA gene sequence analysis. The batch test results showed that all of the strains could degrade phthalate in three days effectively, the degradation efficiencies of DMP, DBP and DEHP were above 65％, 60％ and 30％ respectively. The degradation efficiency decreased with the increasing of phthalate alkyl chain length. The D1-D7 strains all grew with phthalic acid as the sole source of carbon and energy. The utilization of phthalic acid was 18％-39％, which showed that the phthalate could be thoroughly degraded by strains D1-D7 through phthalic acid metabolism pathway.

Abstract:To clarify the effect of propionate concentration on propionate degradation, propionate degradation feature at different propionate concentration conditions was investigated. A mesophilic syntrophic propionate-oxidizing bacterial community (containing propionate-oxidizing bacteria and methanogens) was firstly obtained by 15 times subculture using propionate as sole carbon source. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) revealed that the main propionate-oxidizing bacteria belonged to genus Syntrophobacter while hydrogenotrophic methanogens and aceticlastic methanogens were related to Methanobacterium and Methanosaeta, respectively. Then the batch test was performed for evaluating the effect of propionate concentration on syntrophic propionate degradation. The results showed that the propionate was rapidly degraded at propionate concentration of 1 000-2 000 mg／L under the inoculated sludge of 0.81 g／L condition. However, the propionate degradation was inhabited when the propionate concentration was 2 500-3 000 mg／L. The inhibition was gradually relieved with extension of time. It implied that high concentration propionate (≥2 500 mg／L) would inhibit the metabolic activity of propionate-oxidizing bacteria and this inhibition was reversible.

Abstract:To evaluate the ecotoxicity of nanomaterials, zebrafish embryos were selected as biological subjects, the toxicity of nano-ZnO, nano-TiO₂ and carbon nanotubes on zebrafish embryos hatching rate and teratogenic rate were assessed. Zebrafish embryos of 1 h post fertilization were exposed to a series of different concentrations of nanomaterial solutions, and hatching rate and cumulative hatchability at 36-96 h were recorded. The results showed although Zn2+ has dissolved, But little effect on hatchability,nano-ZnO was more significant inhibition on embryo hatching, in 50 and 100 mg／L nano-ZnO exposure group. Nano-ZnO also causing pericardial edema. Carbon nanotubes did not affect hatching rate but might cause hatching delay, and exert concentration-dose relationship. In the range of this experimental concentrations, acute exposure nano-TiO₂ has no significant influence on hatching rate and malformation rate.

Abstract:To study the relationships between human thermal sensation, thermal comfort and thermal acceptability at the local parts of the body and the overall in cold radiation non-uniform environment, 20 subjects were invited to participate in three experimental conditions, overall slightly cool and overall neutral conditions with asymmetrical cold radiation, and an overall neutral uniform condition. The subjects were asked to report their thermal responses such as thermal sensation, thermal comfort, and thermal acceptability in these three conditions. An overall thermal sensation evaluation model considering local thermal sensation and a thermal acceptability evaluation model based on the maximum local thermal sensation difference were presented,which were both applied to thermal environment with non-uniform radiation from the cold exterior window and wall. The results showed that there was no significant relationship between the overall thermal acceptability and overall thermal sensation, while the overall thermal acceptability was significantly correlated to the overall thermal comfort.

Abstract:This paper proposed a zero-sum magnetic field integral technology to minimize the crosstalk effect in straight light path optical current transducer. The discrete Ampere’s law was proposed and studied based on analyzing of the magnetic field integral along a discrete loop, and its mathematical model was established. The S^m model of regular polygonal discrete loop and the mS^m model of S^m regular distribution were discussed. The results showed that the S^m model possessed 2m zero-sum points, and the currents which placed on the zero-sum points did not contribute to the magnetic field integral result of S^m model. The origin point interchanged with the zero-sum point when any two S^m models of the mS^m model switched places. Based on that conclusion, the zero-sum theorem of S^m model and the reciprocal theorem of mS^m model were proposed. The discrete Ampere’s law, the zero-sum theorem of S^m model and the reciprocal theorem of mS^m model together made up the theory system of magnetic field integral along regular polygonal discrete loop, which still met the Ampere’s law.

Abstract:In this paper, quasi-static tests on 4 connection specimens of reinforced concrete beam-composite column with openings on steel tube were introduced to study the mechanical performance of the core area. The test results showed that the force-displacement hysteretic loops of specimens were plump, and the elasto-plastic deformation capacity of specimens was large. The specimen which the longitudinal reinforcement ratio of beam and of column and the steel ratio of steel tube of column were about same as those of the actual high-rise building failed in bending of the RC beam, and the seismic design requirements of strong column, strong core and weak beam were accomplished. Strengthening the steel tube with openings by welding stiffeners around openings or by thickening the tube wall could improve the shear behavior of the core area effectively, and enhance the shear strength of the core area.

Abstract:To improve the brittle fracture mode of coupling beams with small span-depth ratio in RC frame-shear wall structure, a shape memory alloy (SMA) damper is installed into coupling beams in this study. The seismic performance of the structure is studied by numerical analysis. A planner 18-story frame-shear wall structure is utilized. SMA dampers are installed into coupling beams at each story. Static monotonic and cyclic loading are applied on the structure. Influence of two parameters of the coupling beam with SMA damper, the yield force ratio and the yield displacement ratio, on the nonlinear behavior of the whole structure is addressed. The analysis results indicate that the failure mode is remarkably affected by the yield force ratio. For the structures with the same yield displacement ratio, when their yield force ratio decrease, the dampers yield more early and deformation of the coupling beams is more easily to be concentrated in the dampers. At the same time, the structure has good re-centering ability. With the same yield force ratio, the increasing of yield displacement ratio results in the delay of SMA damper yielding and the concrete members damage early.

Abstract:Anchorage zone is crucial for the cable-stayed bridges and a plane frame model is presented to investigate the performance of the anchorage zone embedded with small radius U-shape pre-stress system, in pylon under different loading stages based on a summary and an analysis of the behavior of pre-stressed cable-pylons, and the expression for calculating the horizontal stress in the critic position of cable-pylon was deduced. A full-scale model test under oblique loading was conducted to analyze the mechanical behavior of pre-stressed cable-pylon according to a practical project and the stress distribution patterns of main members were obtained. The experimental results confirm the practice of the proposed method. The results show that, the pre-stress provides most vertical force to balance the cable load, and the behavior of anchorage zone has slight difference between asymmetrical and symmetrical loadings.

Abstract:To improve calculation efficiency and accuracy of ultimate bearing capacity analysis for concrete filled steel tube arch, based on co-rotational procedure, a numerical model considering material and geometrical nonlinear analysis for concrete filled steel tube beam element is developed. Firstly, based on a linear relationship of strain in co-rotational coordinate system and deformation excluding displace of rigid body, by means of virtue work, a tangent stiffness matrix for material nonlinearity of perfectly-bonded concrete filled steel tube beam element is derived in co-rotational coordinate system without iteration. Then, by building total and incremental relationships derived from differential equations of nodal displacements and forces between global coordinate system and co-rotational coordinate system, respectively, tangent stiffness in global coordinate system concrete filled steel tube beam element is developed considering geometric and material nonlinearity, and unbalanced forces are calculated based on total relations. A comparison between the results in this paper and those from existed references demonstrates that the algorithm in this paper is highly efficient and accurate with many advantages such as non-cumulative calculation errors and reduction in computation.

Abstract:Mode matching problem exists in sectional model flutter tests for a suspension bridge with double main spans. It is necessary to figure out how to match bending modes with torsional modes and seek the mode combination with minimal flutter critical wind speed. According to mode similarity of the Maanshan bridge, three mode combinations were selected. Flutter critical wind speed of every mode combination was tested in wind tunnel tests of sectional bridge model, and then these results of wind tunnel tests were analyzed. The research results show that the mode combination with minimal flutter critical wind speed is the combination matched by first-order antisymmetric vertical bending mode and first-order antisymmetric torsional mode, and it is the key mode combination for flutter of a suspension bridge with double main spans. The flutter critical wind speed for the mode combination of first-order symmetric vertical bending mode and first-order symmetric torsional mode is slightly greater than that for the mode combination of first-order antisymmetric vertical bending mode and first-order symmetric torsional mode. As for empirical formulas of classical coupled flutter, the Van der Put formula and the Selberg formula can estimate the relative value relationship of flutter critical wind speeds for different mode combination, but can’t estimate accurate values.

Abstract:To investigate the influence of end friction on compressive strength with different specimen shapes, we present a three-dimensional particle element approach for concrete, a series of numerical uniaxial compressive tests for standard cube specimen and standard cylinder specimen are conducted. The material properties are assumed to conform to the Weibull distribution law in consideration of its heterogeneity, and a method of parameter inversion calculation is used to get the mesoscopic mechanics parameters based on the material mechanics parameters. The results show that the end friction influences the peak strength, deformation character and failure mode of different geometries of concrete specimen. Shape effect increases as the friction coefficient between the platens of the testing machine and the concrete specimen increases; and the conversion ratio between cylinder and cube strength approaches 0.795 without any friction-reducing measure (f=0.6). The simulation results accord well with the codes, which shows the feasibility and effectiveness of the method.

Abstract:To deal with the stability and stabilization problem of model parameter variation and the large-span maneuver flight of hypersonic vehicles, a robust stabilization control method was presented using switched polytopic systems. The dynamic variables of vehicle envelope were firstly divided into switched polytopic systems, and then the stability analysis was proved by employing switching parameter-dependent Lyapunov functions and the average dwell time method. Finally, the control synthesis was deduced for asymptotical stability of the aircraft dynamics within the envelope. Simulation results demonstrate that the control scheme qualifies satisfactory response and provides satisfactory command tracking, and the proposed method avoids the state jumping in traditional switching controllers and it is with low analysis and design conservation.

Abstract:To improve the reliability of fin stabilizer control system, a fault diagnosis algorithm for the fin stabilizer control system based on UIO is presented. The algorithm improves the deficiency compared with the full order Luenberger fault diagnosis observer when the unknown disturbance occurs in the system. Using the optimal decoupling principle, the UIO fault diagnosis observer which can be decoupled to the unknown disturbances is designed. The existence of the UIO necessary and sufficient condition is deduced and proved for the fin stabilizer control system, and then the UIO fault diagnosis observer design steps are listed. The validity of the algorithm based on the NJ5 fin stabilizer control system is verified. The simulations results show that the proposed UIO optimal fault diagnosis observer has the less state estimation error and faster convergence compared to traditional methods, and it can improve the effect of residual convergence and make a quick response to the system failure in the stage of fault diagnosis.

Abstract:To study the real time problem of nonlinear Kalman filter in SINS／GPS integrated navigation system, the complexity of three usual deterministic sampling nonlinear Kalman filters (UKF, CDKF and CKF) is analyzed and a selection basis is summarized. Numbers of floating-point operations (flops) of the three algorithms are counted according to unified filtering steps, so the accurate expressions of computing complexity are gotten. And a further derivation of the complexity differences among three algorithms is carried out. The aforementioned algorithms are applied in SINS／GPS tightly coupled navigation. Monte Carlo simulation results indicate that three algorithms have similar precision, UKF has the biggest complexity and the complexity of CKF is lower than that of CDKF when the dimension of system states is larger than measurement, and CDKF can get the lowest complexity in some high-dimensional measurement systems.

Abstract:An adaptive backstepping terminal sliding mode controller is designed for ASV with highly nonlinear and uncertain parameters in the reentry phase. Firstly, a strict-feedback nonlinear system with time-varying parameters for the ASV is established. Then, an adaptive strategy is used to estimate the uncertain parameters. Computation explosion is reduced by introducing first-order low-pass filters. In the nth step, the terminal sliding mode control is introduced, which can improve the robustness of system and error convergence rate. The introduced generalized inverse matrix can effectively avoid the singularity in the parameter estimation of control gain matrix process. All errors and states of the closed-loop system are proved ultimately bounded by Lyapunov stability theory. Simulation results of six-degree-of-freedom show that the tracking speed of control scheme is fast and the robust is strong. The control scheme has high adaptability for uncertain parameters.

Abstract:In order to seek the reasonable design method of bidirectional beam string structure, the effect of main geometric parameters on steel consumption was analized. By using the optimization design method of bidirectional beam string structure based on equilibrium load state, the minimum amount of structural steel as the optimization target, the influence to the structure optimization resulted by the high-span ratio, sag ratio, spacing ratio in two directions aspect ratio, the balancing load value and other parameters was discussed. It’s found that the high-span ratio and the sag ratio increasing lead to linear descending of steel consumption. The low influence by spacing ratio in two directions makes the structure space arrangement of ambassador can be flexibly handled. The balancing load has an optimal value and has a big effect to the structure stiffness on load state. Bidirectional beam string structure design should be preferred to increase the high-span ratio and try to increase the sag ratio. Prestress is determined by balancing load caculation.