Abstract:To study the seismic behavior of joints in steel frame with steel-concrete composite beams, 3 quasi-static tests of 1／2 reduced scale joints in steel frame with steel-concrete composite beams were carried out, which mainly focused on the influence of joint location(two middle column joints, a side column joint) and effective width of concrete slab on seismic performance of the composite joints. The failure mode of the joint, the hysteresis curve, energy dissipation capacity, ductility, strength degradation and stiffness degradation properties have also been studied. ABAQUS software has been used to analyze the elastic-plastic performance of the joints under monotonic loading. The finite element analysis results are in good agreement with the experimental results. It is shown that deformation capacity and energy dissipation ability of joints are high; strength degradation and stiffness degradation are not obvious; joints location and the effective width of concrete slab have much influence on the seismic performance of the joints.

Abstract:To offer the distribution of the temperature field and thermal stress for steady state convective heat transfer condition of LNG tanks on leakage occasion, the behaviors of a 1 600 000 m³ LNG outer concrete tank are studied by ANSYS. Via thermal-structure coupling analysis, cases combinations between the thermal stress on LNG outer concrete tank wall and different static forces are calculated. The most adverse envelope diagram under static load is obtained, and then the configuration of circumferential pre-stressed reinforcement is proposed. The numerical results show that the temperature stress makes the LNG outer concrete tank a shrinkage deformation tendency; the liquid pressure is the dominating influence factor on deformation and internal forces of the outer tank structure; the weakest part is located at about 10m from the bottom.

Abstract:To determine the stop time of disaster emergency, the states of emergency were divided into two kinds of states, including emergency tension state and emergency stationary state after analyzing the influence factors of emergency termination states. Firstly, the maximum time N was found out by Markov decision model after the emergency state going into the stable phase, and then the optimal stop theory was used to solve the question of the emergency termination to find the most optimal termination time during the N, finally, the Markov chain's decision model of emergency state termination was established, which could accurately solve the question of the quantification decision of the end time of emergency state, and the calculation was simple. Markov model provided the theory support for emergency termination decision.

Abstract:To investigate the maximum concentration of manganese of groundwater containing high concentration of iron, manganese and ammonia nitrogen groundwater in a biological iron and manganese removal filter, a mature and steady operated biological filter was used, and the concentration of manganese in influent was increased gradually. Results showed that in the experimental conditions of the concentration of total iron and ammonia nitrogen was 5-0,0.9-1.3 mg／L, respectively, the temperature of raw water was 8 ℃, and the flow rate was 6 m／h, when the dissolved oxygen (DO) in influent was about 8.5 mg／L, the maximum concentration of manganese was 7.5 mg／L; when the DO was above 10 mg／L, the maximum concentration of manganese was 10.5 mg／L. There was no influence of manganese concentration increased in influent on iron and ammonia removal. Variation of iron, manganese and ammonia nitrogen removal along the filter showed that along the filter depth, manganese removal quantity reduced in the same depth of the filter, the efficiency of ammonia removal did not change along the filter depth in manganese concentration increased process. The maximum concentration of manganese was limited by DO, the DO in influent was higher, the concentration of manganese was higher.

Abstract:The feasibility of completely autotrophic nitrogen removal process (CANON) for treating domestic sewage at ambient temperature was investigated in MBR. Firstly, the hydraulic retention time (HRT) was gradually reduced without variation of influent ammonia for enriching AOB, then HRT was further decreased with the reduction of aeration rate for enriching anammox, and DGGE was adopted in this study for analysis of the community dynamics in different phases. CANON was successfully started-up within 78 days, finally total nitrogen removal rate reached 0.96 kg·m-3·d-1 with the removal efficiency of 80％, COD and ammonia were simultaneously removed when treating domestic sewage. Phylogenetic analysis indicated that Nitrosomonas related ammonia oxidizing bacteria and Candidatus Kuenenia stuttgariensis like ANAMMOX bacteria existed in the reactor. The MBR-CANON system was feasible for treating domestic wastewater at ambient temperature.

Abstract:To thoroughly investigate biochemical characteristics of the humic activated sludge and action mechanism, the humic biological pellets were tested by means of SEM-EDAX. The results show that the main composition elements in humic biological pellets are C, O, Si, and there are small amounts of Al, S, Fe. Compared to conventional activated sludge, the number of typical bacteria, nitrifying bacteria, nitrosobacteria, denitrifier and actinomycetes in humic activated sludge were significantly higher. Organic matter content in humic activated sludge is less than that in conventional activated sludge, but the humic acids content is higher. The humification degree of humic activated sludge is considerably higher than that of conventional activated sludge. The SBR reactor operated under humic activated sludge process performed excellent pollutant removal efficiency than conventional SBR reactor, the removal efficiency of CODCr, TN and TP is 4％, 10％ and 14％ higher respectively.

Abstract:To realize the stable and efficient operation of biogas digester in cold region, a combined regulation technique of microbial community should be established. The microbial community in the largest full-scale digester of Hailin Farm was investigated using 454 pyrosequencing technology and PCR-DGGE. The massively parallel sequencing technology was used to measure bacterial diversity of biogas slurry during a stable operation. A total of 1297 sequences were obtained, and the dominant bacteria were Firmicutes, Bacteroidetes and Proteobacteria, which accounted for 46.39％, 21.41％ and 18.98％, respectively. At genus level (the relative abundances>5.0％), Proteiniphilum, Spirochaeta and Wolinella were the abundant taxa. The diversities of methanogen were analyzed using PCR-DGGE, and the detected archaea were Methanocorpusculum sp., Methanosaeta sp., Methanobacterium sp. and Methanosarcina sp.. Notably, the methane produced by acetoclastic methanogens, and dominant fermentative bacteria during the hydrolysis and acidogenesis were detected form animal digestive system.

Abstract:Penicillin fermentation dregs, municipal sludge and saw dust were used as composting raw material to analyze the effect of antibiotic residue on aerobic composting process in this paper. The variation of such physicochemical parameters as temperature, carbon and nitrogen and the degradation of penicillin were analyzed during the aerobic compost process. The feasibility of composting with fermentation dregs was analyzed using 0.4 m3 volume reactors and the detail compost process were analyzed using five 6 L volume reactor. Results show that the temperature rise rate of co-compost process has an advantage over municipal sludge compost process. The content of total organic carbon (TOC) in mixed material is directly proportional to fermentation dregs, which also decreases with compost time and tends to stable finally. Results also show that the penicillin residue doesn’t affect the TOC varation trend. The water soluble organic carbon (WSOC) and microbial utilization carbon increases with the adding fermentation dregs, which is helpful to microbial transformation and contribute to increase the compost temperature. Adding fermentation dregs is also helpful to reduce the loss of nitrogen and no penicillin residue can be detected on the 5th day of composting process, which shows the resource utilization of fermentation dregs and the degradation of antibiotic residue can be achieved by co-compost process.

Abstract:The aim of this paper is to improve the performance of the non-linear eddy viscosity model for simulating the wind flow around the building. Firstly, the state of art of the predicting wind flow around building using RANS model was introduced, and the problems in the simulation were analyzed. Then an improved non-linear eddy viscosity for predicting the wind flow around buildings was proposed based on Craft model. The improved non-linear eddy viscosity was validated and analyzed through the wind tunnel data provided by AIJ. The results showed that the proposed non-linear eddy viscosity improved the overestimation of turbulent kinetic energy in impingement region by the standard k-ε model, and predicted better results in the wake region behind buildings simultaneously through strengthening the eddy viscosity in the wake region. After the improvement, the non-linear eddy viscosity model can predict the wind environment around buildings better.

Abstract:In order to determine the spraying amount of waterproof binder for bridge deck pavement, rubber modified binder and two typical kinds asphalt mixtures were used to analyze different factors that affect the shearing properties of waterproof bond layer by skew shear test and direct shear test, the mechanical properties of waterproof bond layer was also studied in the paper. The results show that the maximum shearing stress increases linearly as the loading speed increased, the temperature also has significant effect on the shear performance of waterproof bond layer, with the increase of temperature, the shear resistance performance became worse dramatically. The shear stress and deformation obtained from shear test can be used as the indicators to evaluate the shear resistance performance. Based on the research of above, the method of determining binder spraying amount can be proposed.

Abstract:To improve the performance of servo system, online suppression of mechanical resonance based on adapting notch filter is adopted. The expansion of bandwidth in servo system will exceed the natural mechanical resonance frequency. The originally ignored influence of elastic components will be more obvious, and mechanical resonance is caused. Firstly, the theoretical analysis of 2-mass model with elasticity load is carried out. The results of simulation verify this resonance mechanism and phenomenon. By FFT method to real-time analyze the electromagnetic torque current, resonance characteristic can be identified online and quickly. Based on identification result of resonance characteristic, parameters of notch filter can be online-set automatically. It can suppress mechanical resonance quickly and effectively. Experiment results show this method can online-suppress the resonance caused by elastic load automatically. Resonance system with high stiffness sustained oscillates at natural torsional frequency when the system is discretized. This method which uses adapting filter to suppress mechanical resonance doesn’t need to change the parameters of controller while high stiffness of control is satisfied.

Abstract:The problem of detection for range spread targets is analyzed in complex clutter with unknown statistical characteristics. With polarization information of radar echo and training data available to estimate covariance matrix of clutter, a generalized likelihood ratio test (GLRT) based adaptive polarimetric detector is proposed. Then, the analytic expression of false alarm probability is derived to prove constant with respect to the clutter energy and clutter covariance matrix in theory. The simulation results show that the adaptive polarmetric detector achieves good detect probability even at a low target to clutter ratio, and has better detection performance than the adaptive polarimetric detector of point target and the adaptive detector using single polarization.

Abstract:To investigate the effect of ductile material on strength and ductility improvement of concrete, the flexural performance of LSECC-Concrete composite beam, in which the ductile fiber reinforced cementitious composite with characteristic of low shrinkage (LSECC) was used at the tensile part of the beam, was studied by both experiments and theoretical simulation. The results show that the concrete beam combined with ductility material at the bottom of beam can achieve a high ductility and enhance load carrying capacity. The strength of the LSECC and plain concrete, as well as the thickness of LSECC layer used in the composite beams can greatly influence the strength and ductility of the beam. Based on cracking strength criteria and stress-crack opening relationship, a model to simulate bending performance of composite beam is developed, which can well predict the flexural behavior of composite beam. A seasonable agreement between model and test results is observed and the model may be used in optimization of the composite structures.

Abstract:To determine the scope of self-centering for the tall pier with pile foundations, the effect of near-field ground motion on rocking response was investigated. Fault distance was used as parameters identifying near-field to select ground motion. Two springs simulated the uplift and rocking of the pier. Rocking response of a railway tall pier was investigated through nonlinear time history analysis by inputting strong ground motions. The results show that the displacement at pier top is significantly increased by near-field horizontal ground motion. It is also observed that vertical ground motion is unfavorable to the rocking response of tall pier with pile foundations. Rocking devices for tall piers in near-fault zones should be cautious.

Abstract:Eight ultra-high performance concrete T-beams subjected to bending were tested to investigate their cracking moments and cracking characteristics and evaluate the formulas for cracking moment and crack width specified in existing design codes. The test results show that the degree of prestress has a great impact on the cracking moment; the bending cracks are dense and fine, the development of the maximum crack width is slow at the early stage of loading and speeds up remarkably when the reinforcements reach to yield strength. Predicating the cracking moment and maximum crack width by existing code formulas will lead to overly conservative results. The modified formulas of cracking moment and crack width are suggested for ultra-high performance concrete beams by introducing the anti-cracking effect coefficient and crack-correction coefficient respectively, and the calculated values by the suggested formulas agree well with the test results.

Abstract:In order to understand the dynamic strength properties of the concrete under complex stress state, a united multiaxial static-dynamic strength criterion is established in the octahedral stress space in which the strain rate effect is considered. The failure surface of the proposed model in three-dimensional (3D) stresses space is represented by a quadratic function. The strength envelope in the deviatoric plane is described by an elliptic curve similar to that of Willam-Warnke model, and the tensile and compressive meridians are calibrated using typical stress points method to consider the effect of the Lode angle on the dynamic strength. By the analysis of multiaxial static and dynamic strength test data of concrete, it is proved that the predicted strength of the failure criterion is in good agreement with the experimental data. Meanwhile, the strength criterion has simple expression form and is convenient for practical application.

Abstract:To study the dynamic response of the structure with suspended mass under coupled horizontal, vertical and tilt ground motions, the dynamic equation of the structure under coupled horizontal, vertical and tilt ground motions was derived. A modified method was proposed to obtain the tilt component. Taking a valve hall with suspended mass as prototype, the shaking table test of a 1∶10 scale model was carried out, and the seismic responses of structure under coupled horizontal-vertical, tilt-vertical and horizontal-vertical-tilt when different lengths of steel cable and spring to hang the mass. The results show that, compared with under horizontal component, the damping effect of suspended mass on main structure under tilt component is more obvious. The damping effect of suspended mass on main structure decrease as the length of steel cable or spring grows. When using spring of the same length to replace steel cable, the changes in acceleration and displacement on the top of structure are not big, but the dynamic tension of cable decreases. Thus, when suspended mass is used as damping system, the cable should employ spring or the member with low axial rigidity.

Abstract:To further identify the dominant pollutant of PVDF UF membrane, the secondary wastewater effluent organic matters were isolated into strongly hydrophobic acids, weakly hydrophobic acids and hydrophilic matter by DAX-8／XAD-4 synthetic resins and then the filtration tests were conducted with each constituent. The membrane-foulant and foulant-foulant interaction forces were measured with homemade PVDF micro-particle probes and the corresponding foulant-coated probes respectively with atomic force microscopy, as well as membrane morphology. The results showed that the microscopic force could effectively predict membrane fouling behavior. Adhesion between hydrophilic matter and PVDF membrane was the biggest, whereas adhesion between weakly hydrophobic acids and PVDF membrane was the smallest. The membrane-foulant force was bigger than the foulant-foulant force, illustrating that membrane-foulant force was the key factor to control the fouling behavior of PVDF UF membrane, and an effective mean to control PVDF UF membrane fouling was to reduce the force between the hydrophilic matter and PVDF membrane.

Abstract:To explore the applicability of modeling on fuzzy sub-cluster in the pore structure of porous materials, aiming at theuncertainty of the pore structure of hardened gypsum,and according to particular property of the fuzzy sub-cluster in the multilayer, fuzziness and most probable pore, the relationship between its and the porosity, pore size distribution and most probable pore for building hardened gypsum are analysed. The porosity of hardened gypsum at different water／gypsum ratio is measured by using bulk density and the pore size distribution and most probable pore of hardened gypsum at different water／gypsum ratio has been experimented by adopting nitrogen adsorption porosimeter and mercury porosimeter respectively. The result shows whatever you use nitrogen adsorption porosimeter or mercury porosimeter, based on test of most probable pore, the competitive parameters about large or small pore size of hardened gypsum at different water／gypsum ratio are obtained by employing fuzzy sub-cluster.For porous materials, complicated pore structure may bequalitative or quantitative analysis by means of fuzzy sub-cluster so that study of the effect porous material on the thermal and moisture transfer.

Abstract:To analyze the condition of setting bus lane more accurately, a basic road speed model was introduced with its applicability. The model’s formulation of vehicle and bus was modified by considering different traffic parameters as vehicle volume, bus volume and ratio of bus. To calibrate road speed models respectively, the empirical data from two three-lanes one-way road section with and without bus lane was collected. Comparing the regulation of different speed between the traffic flow with and without bus lane, shows that the speed varied for two distinct intervals of no difference and the difference increased with the change of road traffic volume (saturation). Furthermore, the time utility models were set up to describe the traffic volume condition of setting bus lane. The conclusion shows that the traffic volume condition is lower than traditional standard when the proportion of bus is low and vice versa. The proportion of traffic in the composition of public transportation would help refine the different discrimination of setting bus lane.

Abstract:In order to solve the harmonic issues that exist in multiphase motor systems normally, and find the appreciate approach PWM technology for decreasing the total harmonic distort (THD), this paper studied several PWM technologies which can be used in multiphase motor’s control systems: the maximum vector SVPWM, the space multidimensional vector SVPWM and the carrier-based multiphase PWM, the principle and the implement method of these PWM technologies were given. This paper analyzed the 15-phase permanent magnet synchronous motor control system by Matlab／Simulink model, the simulation results indicated that the motor phase current which used the carrier-based multiphase PWM has lowest content of harmonics and better performance.