Abstract:To improve the explosive spalling and compressive properties of reactive powder concrete (RPC) at elevated temperature, 108 cube specimens (70.7 mm×70.7 mm×70.7 mm) were prepared to study the compressive strength of RPC with polypropylene fibers (PPF). The influences of temperatures and PPF content on the spalling properties of RPC were investigated, and compressive strength of RPC with different temperatures and PPF content were studied. The experimental results show that PPF volume content of 0.3％ can prevent explosive spalling of RPC and significantly increase compressive strength. Compressive cube strength drops at 100 ℃ as compared to 20 ℃ and increases from 200 to 600 ℃, but drops again beyond 600 ℃; Compressive cube strength of the RPC was lower if the PPF content increases below 100 ℃, but was higher when the PPF content increases between 200 and 800 ℃; The relative compressive strength of RPC was lower below 500 ℃, but was higher between 600 and 800 ℃. Calculation formulas of the compressive strength at elevated temperature were obtained by fitting curve of experimental data considering PPF content when temperature varied.

Abstract:To investigate the influences of uncertainties on stable bearing capacity of CFST arches, the limit state function for lateral instability is established. The software ABAQUS is used to calculate the ultimate bearing capacity or critical load for stability with or without considering nonlinearities. Based on the FORM, the cooperative work of self programming with MATLAB and finite element software is adopted to obtain reliability and sensitivity indices for different initial loads. The results show that the real bearing capacities of CFST arches for lateral stability lie between critical load and ultimate bearing capacity, and the critical load is the upper limit. The geometric size has the most important influences on reliability index and it is followed by the elastic modulus and the material strength. The initial geometric imperfection has little effect within the limit of code. However, with the increasing of lateral load, the sensitivity indices of material strength increase, while the sensitivity indices of elastic modulus decrease.

Abstract:To predict the bridge structure performance based on inspection information and the priori model of bearing capacity, the dynamic measure of structural performance over time is treated as a time series, a Bayesian dynamic linear model (DLM) is then introduced. Considering the time-dependent characteristics of structural performance of the considered bridge, this paper proposes the probability method of bridge resistance degradation predication. State equation and observation equation of resistance degradation are established with Bayesian dynamic linear model. Combining parameters’ prior information with the early resistance observation data containing noise, the resistance degradation state parameters are deduced with Bayesian Posterior Probability. A dynamic linear model is built to forecast the short-term trend of structural resistance. The one-step-ahead forecast distribution and the filtering distribution are determined for Bayesian dynamic updating. To allow for the epistemic uncertainty in variance estimation based on inspection information, a discount factor approach is made for specification of unknown variance matrix. Finally, a RC girder is taken as an illustration example to demonstrate the applicability of the proposed method.

Abstract:To study the influence of integral scale on buffeting response of long-span bridge which cannot be taken into account in the passive turbulence wind tunnel test and to provide a reasonable evaluation of wind tunnel test result, taking a typical cable-stay bridge and a suspension bridge as samples and combining aerodynamic parameters of the section model in wind-tunnel test, the influence of turbulence integral scale and wind spectra on buffeting responses were studied in frequency domain. The results show that buffeting responses decrease with increase of integral scale at lower wind speed; while at higher wind speed, buffeting responses increase first and then decrease. After comparing the integral scales in wind tunnel test and in wind standard, the result shows that buffeting response in wind tunnel were overestimated at lower wind speed, but underestimated at higher wind speed. After comparing the influences of several frequently-adopted horizontal and vertical wind spectra on buffeting response, the result shows that the influence of different horizontal wind spectra can be neglected, but the influence of different vertical wind spectra should be taken into account.

Abstract:To investigate the efficiency of treating micro-polluted reservoir water from the Yellow River using PAC-MBR, four processes combined with coagulation (ployaluminium chloride and ferric chloride), coagulation-sedimentation and coagulation-air flotation were discussed, from the view of pollutants removal and membrane fouling, comparison with conventional treatment process/+UF were also made.The results showed that all these processes guaranteed the turbidity and particle counts of effluent at 0.02 NTU and lower than 50 mL-1, with the removal efficiency above 98％ and 95％, respectively. The average effluent UV₂₅₄ ranged between 0.043 and 0.045 cm-1,and the removal rate were (18.28±9.35)％, (16.76±6.14)％, (3.23±1.26)％ and (6.38±2.26)％, respectively. The average effluent CODMn ranged from 1.85 to 1.94 mg/L,with removal efficiency of (4.22±7.49)％, (33.20±6.99)％, (22.20±8.91)％ and (41.72±14.25)％, respectively. As for particulate and organic matter, the removal efficiencies of hybrid processes were superior to conventional treatment process and almost equal to UF membrane combined processes in Nanjiao Water Treatment Plant. The NH₃-N removal was above 95％, and the accumulation of NO₂--N was not found. Considering the effect of eliminating membrane fouling, coagulation-sedimentation and coagulation-air flotation effect were the best, followed by ferric chloride, but that of polyaluminium chloride was the worst.

Abstract:This paper described the developments in the methods of EDCs detection. Biologically based assays, which comprise whole organism assays, cellular bioassays and non-cellular assays, seem to be promising methods for the determination of endocrine activities. On the other hand, the mass-based analytical methods show excellent sensitivity and precision for EDCs’ quantification. Several extraction techniques for the instrumental analysis have been developed since they are crucial in determining the overall analytical performances. To achieve both quantitatively and qualitatively successful analysis for EDCs, a combined approach incorporating two types of analyses was proposed, known as a bioassay-directed chemical analysis (BDCA) method. Further studies on EDCs need to be conducted, such as source reduction, limiting exposure to vulnerable populations, remediation of contaminated sites, and the detailed understanding of transport mechanisms in the environment.

Abstract:To improve the efficiency of cross-regional environmental integrated and coordinated management, protect the limited water resources and avoid the transboundary water pollution caused by environmental disputes, the current situations of cross-border region water environmental information sharing and opening are analyzed. From the four aspects of water environmental information content, water environmental information sharing ideas, transfer mode and sharing system, the regional water environmental information sharing mechanism are established. The cross regional water environmental information sharing system is an important part of national basic information resources, which enhances the emergency response capability of regional environmental supervision, and expands the public's right to know and the right to participate in environmental issues.

Abstract:The Fe/C micro-electrolysis and Fenton combined process was used to solve the high yield organic CLT acid wastewater in our country. The influence factors of pH, reaction time, ratio of iron and coke, H₂O₂ dosage and reaction time of H₂O₂ were investigated. The results show that when the influent COD is 28.1 g/L to 34.5 g/L, pH is 2.5, ratio of iron and coke is 2∶1 and the reaction time is 60 min, the removal rate of COD by ferric-carbon micro-electrolysis is above 30％. For treatment with the Fenton when the H₂O₂ (30％) dosage is 0.15 mol/L, the reaction time is 60 min and the temperature is 20 to 30 ℃, the removal rate of COD reaches more than 43％, B/C ratio of wastewater increases from 0.08 to 0.43.

Abstract:The release rate of soil CO₂ and its factors were measured with CIRAS-2 portable photosynthesis system, then their relationship was analyzed to investigate the influences of the additional nitrogen fertilizer, phosphate fertilizer and arbuscular fertilizer on characteristics of soil CO₂ release in paddy. The results showed that: (1) The addition of nitrogen fertilizer resulted in soil CO_2release rate rising by 97.73％ in 0 cm layer, and dropped by 39.93％ and 31.36％ in 10 cm and 20 cm layer, respectively. (2) While there was no significant difference between soil CO₂ release rates after the addition of phosphate fertilizer and of CK in 0 cm layer, the rate dropped 33.84％ in 10 cm layer and rose 48.03％ in 20 cm layer. (3) The additional arbuscular fertilizer had no significant influence on all three layers. (4) The related coefficients of soil CO₂ releasing rates and their factors in the same layers were affected by the fertilizer-modes, and its impact became lighter with the increasing of depth. Compared with nitrogen fertilizer and phosphate fertilizer, mycorrhizal fertilizer had no significant influence on the soil CO₂ release.

Abstract:The influences of different fixed ways of polyurethane on the purification performance of wastewater treatment in biological contact oxidation were discussed, the polyurethane was put into biological contact oxidation by up-floating, sinking and general up-floating general sinking respectively, the relationship between microbial community structure and purification performance was analyzed. The results showed that polyurethane fixed by general up-floating general sinking could most efficiently remove pollutants, the purification rate of COD and NH+₄-N were 90％ and 94％; the attached microbial populations were with the largest number, the highest diversity, the strongest activity and the most reasonable function in this way. Therefore, the purification performance was affected by the fixed way of polyurethane in biological contact oxidation and the general up-floating general sinking was the most effective fixed way.

Abstract:Method of mixed culture,earlier autotrophic condition and later heterotrophic condition, was used to enrich heterotrophic nitrifying bacteria and aerobic denitrifying bacteria from marine aquaculture wastewater. Heterotrophic nitrifying bacteria and aerobic denitrifying bacteria were isolated and purified by the heterotrophic culture medium. Using the special PCR primers, the bacteria were rapidly screened by amplifying Ammonia monooxygenase encoding gene (amoA) and a subunit of periplasmic nitrate reductase (NAR) encoding gene (napA). Those bacteria were identified by the denitrifying test. 22 heterotrophic bacteria strains were isolated, 11 strains had the amoA gene, 7 strains had both of the two genes, and there were 9 strains which had nitrifying ability.

Abstract:To more precisely describe the effects of non-uniform buildings on atmospheric dynamics in parametric numerical models, this paper set up a morphological parameterization method to represent the non-uniformity of buildings according to the geometric morphology of buildings, including the frontal area index (λf), the plan area index (λp), the shape index (SBC), and the integrated non-linear coefficient (R). Wind tunnel experiments were carried out to study the effect of buildings morphologic parameters on drag force. A floating experimental platform was designed to measure the drag force of the whole area. Results show that, different roughness of surrounding landforms has little effect on the drag coefficient, the frontal area index is the main factor of wind direction on the drag coefficient. The drag coefficient increases with the increasing of frontal area index, density index, shape index and the decreasing of integrated non-linear coefficient, respectively.

Abstract:To scientifically select and evaluate ultra-thin wearing course asphalt mixture, three types of asphalt mixture, SMA-10, UTAC-10 and NovaChip Type-C were selected to study the performance evaluation indicator. The low temperature performance of mixture was evaluated by use of thermal stress rest rained specimen test, and the surface performance was evaluated by permeable coefficient test and anti-slide performance test. A kind of indoor abrasion test was designed to evaluate the skid resistance attenuation property of asphalt mixture, and a set of dispersion tests under three conditions was designed combining with freeze-thaw splitting test to evaluate water damage resistance performance of asphalt mixture. The results show that the frozen broken temperature and frozen broken strength can effectively evaluate the low temperature performance of ultra-thin wearing course asphalt mixture. It is scientific to use initial value of BPN and sliding attenuation degree to evaluate skid resistance performance of ultra-thin wearing course. Freeze-thaw splitting strength ratio and freeze-thaw splitting strength should be combined to evaluate resistance water damage performance.

Abstract:To solve the problem of unstable operation caused by capacity limitation of microgrid storage system, this paper presents an improved microgrid cooperative control strategy, of which the structure is double-layer of cooperative control, that is the primary control is the battery energy storage system and the secondary control is a microgrid management system (MMS). The primary control ensures that the frequency of the microgrid is within the acceptable range, while the secondary control ensures the largest spare capacity in the microgrid. To accurately describe the different types of distributed power of the prime mover to affect the microgrid system, by using detailed micro-source model, a microgrid simulation system is established and simulated. The simulation results show that the cooperative control strategy has a good dynamic performance, and ensures the quality of power supply requirements. Therefore the cooperative control strategy of microgrid has a better application prospects.

Abstract:To study the effect of branched spacer on the property of Gemini imidazolium surfactants, Gemini imidazolium surfactants of 2,4-［bis(3-alkylimidazolium-1-yl) bromide］-1,3-propanediol (［C_n-P-C_n］Br₂, where n is the hydrocarbon chain length of 0,2 or 14) were synthesized with 2,2-dibromomethyl-1,3-propanediol as the spacer. Their surface activity and thermodynamic properties of micellization were characterized by surface tension and electrical conductivity measurements. The values of critical micelle concentration (ccmc), saturation adsorption values at the air/aqueous interface (Γmax), the area per surfactant molecule at the air/aqueous interface (Amin), the efficiency of adsorption (pC20) and surface pressure (πcmc) derived from surface tension measurement at 25 ℃ suggested that the surface activity of ［C_n-P-C_n］Br₂ was high. While Gibbs Free Energy of micellization (ΔGm) of all the surfactants derived from electrical conductivity were all negative, indicating that the formation of micelles was spontaneous.

Abstract:A model for simulating the pile-soil interaction was presented in this paper to investigate the influence of soil under pile tip on the pile impedance. In this model, the diffusion of additional stress in the soil surrounding pile tip coincides with the Boussinesq’s solution under circular loading. The soil in the main zone of the stress diffusion is treated as a fictitious soil pile. The vertical displacement at the bottom of the fictitious soil pile is restrained by bedrock. The impedance on the fictitious soil pile top is obtained via the boundary conditions at the bottom of fictitious pile and impedance transfer method. This serves as the supporting condition of the actual pile, which can be further used to solve the impedance response of the whole pile system. Results of the proposed model are compared with those obtained by Novak’s method. It is found that it can yield more accurate prediction of impedance response of pile when considering the stress diffusion in base stratum. Pile damping is proportional to the thickness of base stratum, while the stiffness is on the contrary. For the pile with smaller slenderness ratio, the influence of the stratum under pile tip is more obvious on impedance.

Abstract:To obtain a good prediction of the grouted pile behavior under vertical loads, an iteration method based on the hyperbolic load transfer function is developed to determine the load settlement relationship of the grouted pile in this paper. The calculation procedure for a single grouted pile in layered soil is presented. Four improvement factors are introduced to account for the effect of grouting on the side friction and end resistance. The empirical range of the improvement factor is also given based on statistical analysis. Finally, a case history is cited to indicate the validity of the presented method. The results show that the presented method can predict the range of load settlement relationship of the pile head well. It is suggested that the predicted lower bound can be used for a conservative design.

Abstract:To determine the steel corrosion model of in-service reinforced concrete (RC) bridge more reasonably, the existing research literatures on steel corrosion were reviewed and compared and a revised steel corrosion model by considering the load effect and chlorine ion combining ability was developed. The model was used in study of in-service reinforced concrete bridge near coastal areas, and its validity was verified. The result shows that the model is more reasonable when compared with the traditional chloride diffusion models. It is practical to adopt the model for simulating materials deterioration and predicting structural service life.

Abstract:By lateral cyclic loading test, hysteretic behavior of seven circular RC columns confined by lateral pre-stress under high axial compression was studied. Using theoretical analysis and statistic regression analysis, the formula of calculated flexural capacity for columns is proposed. The three line restoring force model of circular RC columns under high axial compression confined by pre-stressed CFRP belts which is capable of considering the pre-stress of CFRP belts and axial load ratio is set up. Test results show that the hysteretic behavior of the columns with high axial load ratio is improved significantly after confined by pre-stressed CFRP belts. The diagonal shear cracks of columns can be effectively confined with the active lateral stress provided by pre-stressed CFRP belts, and the failure mechanism of the columns with high axial load ratio may be changed from shear to flexure with satisfactory ductility. The result of the recommended model shows good agreement with the test result.

Abstract:During the design of anchor foundation of offshore structures, aiming at the investigation of the ultimate pullout bearing capacity analysis of drag embedment anchor under cyclic loads of wind, wave and current, the undrained seabed soft clay and drag embedment anchor are respectively simulated by ideal elastic-plastic model and rigid model. Considering the contact friction between the drag embedment anchor and seabed clay, the two-dimensional finite element calculation model is established. Under cyclic loading, concept of cyclic strength from Anderson is introduced, and then the influence laws of embedment depth and load cycle times to ultimate cyclic pullout bearing capacity of drag embedment anchor are respectively investigated. The results show that the embedment depth has little influence on cyclic ultimate pullout bearing capacity. With the load cycle times gradually increasing, the cyclic ultimate pullout bearing capacity of drag embedment anchor gradually decreases and the decreased degree gradually becomes small. The specific numerical results and analysis conclusions would be helpful in engineering practices.

Abstract:Studying biofilms in long-distance raw water diversion pipe is beneficial to the analysis of water quality and the security of raw water quality. Therefore, the characters of morphology, microstructure, spatial and temporal distribution of biomass and microbiota community of bio-films in long-distance raw water diversion pipes were investigated using the simulated process of 8 bio-film annulus reactors (BAR) in series with different raw water. The results showed that the bio-film structure was significant different in water quality, and the particle color attached in pipe bio-film was an important influencing factor in the characters of morphology. Secondly, the structure of the rough bio-film changing with water flow increased the specific surface area of the bio-film which led to the growth and development of bio-film and pollutant removal. Thirdly, the biomass of A raw water reached the peak(1.11 nmol·cm-2) in BAR3 running 75 d, and then became lower due to the less nutrient. However, the biomass along simulated pipes of B water changed subtly because of the limited DO(0.3-3.0 mg·L-1). Finally, the microbiota composition is highly correlated with the water quality, reacting water quality and purification effect.

Abstract:To evaluate the pedestrian-vehicle conflict safety in mixed traffic condition, this paper analyzes and compares the commonly used parameters on traffic conflict and presents a model to classify independent pedestrian-vehicle conflict safety. The model is validated by using video data from two different traffic scenes. The result shows that the pedestrian-vehicle conflict safety is highly sensitive to the Time Difference to Collision (TDTC) parameter and the vehicle speed. The closer to zero a TDTC value is and the faster a vehicle is, the more dangerous a pedestrian-vehicle conflict may be. Comparing with independent observation, the model can correctly classify about 86.2％ conflicts; only 2.1％ conflicts are classified as safer by the model.

Abstract:The omnidirectional walking robot with a steering-wheel synthesizes the mechanism features of legged robot and vehicle’s steering wheel. To investigate the kinematic characteristics and motion control systematically, the design idea, mechanism features and kinematics principle of the robot are introduced. Then an equivalent manipulator model is built, the Jacobian of the manipulator is given and dynamics both in joint space and Cartesian space are developed, the resulting nonlinear closed-loop control system can be obtained based on the formulated dynamics equations. The co-simulation PID control of omnidirectional motion is implemented based on ADAMS and Matlab/Simulink, the experiments on the prototype is performed. The simulation and experiments validate that the robot with a steering wheel can be manipulated flexibly and accurately in omnidirectional motion, and the control method is simple and reliable.

Abstract:To reflect the influence of uncertain demand to bus frequencies, transit network robustness performance was adopted to optimize the bus frequecies. A bi-level programming model was presented in the process. After the analysis of demand variation propagation in the passenger assignment process, the upper-level model was put forward by the analytical method. There were two items in this model, the former was transit network system benefit consisted of passengers’ costs and operating costs, and the latter was transit network robustness performance. The objective of lower-level was to assign transit trips to bus route network based on optimal strategy. The adopted genetic algorithm to the model was illustrated with a test network and a city network of Liupanshui. It indicated that the transit network robustness performance could improve the reliability of bus frequencies.

Abstract:To explain the reasons of influencing public acceptability of congestion pricing from psychological point of view, and reveal the influence law of psychological factors on acceptability, the structural equation model of public acceptability is built with psychological factors social norm, problem perception, personal norm, perceived behavioral control, behavioral intention, perceived effectiveness, equity and freedom. A scale is developed to measure these psychological factors. Single congestion pricing policy and combined measure of congestion pricing to improve transit are investigated by the scale. The default structural model is fitted and estimated by 897 samples of car user. The results show that the explanatory factors for acceptability are not significantly different between two measures, perceived fairness, freedom, personal norm and perceived behavioral control have direct impact on acceptability. The perceived fairness and freedom are the key factors to affect the public acceptability. The model results may provide a basis for managers to increase the acceptability of congestion pricing policy.

Abstract:To overcome the problem that the algorithm is not stability because the observation dimensions increases in gravity gradient aided positioning, the system posterior probability density narrows and the particle degradation of the conventional particle filter intensifies, an improved particle filter based on artificial physics is introduced to optimize the particle distribution. The improved method incorporates Artificial Physics Optimization into resampling process of the generic particle filter to overcome the problem of particle degradation and sample impoverishment. The improved particle filter is applied into gravity gradient aided positioning by combining the sea experiment data of an inertial navigation system. The artificial physical optimization enables to improve particle degradation and optimize algorithm stability. After optimizing, the algorithm is adopted in gravity aided positioning, which has better estimation precision.