Abstract:To fully investigate the influence of modeling uncertainty on reliability of structures,in this paper,the statistical reliability problem of structures considering two kinds of uncertainties,i.e.,physical uncertainty and modeling uncertainty is deeply studied on the basis of Bayesian statistics.First,the fundamental principles of Bayesian statistics are summarized.The modeling uncertainty in structural engineering is then modeled and analyzed by Bayesian updating approach,and the various measures for structural statistical reliability are introduced.To treat with the aleatory and epistemic uncertainties,two methods,i.e.,the integrated approach and the separate approach for statistical reliability analysis of structures considering both physical uncertainty and modeling uncertainty are proposed.Two examples are given,one of which is a numerical one;the other is a problem of soil liquefaction.The examples demonstrate the effects of modeling uncertainty on the reliability indices of structures.

Abstract:It is very important for the design of composite columns to accurately evaluate the maximum depth-to-thickness ratio for which local buckling can be ignored and to determine the actual bearing capacities of slender columns which are influenced by local instabilities.This paper studied the behavior of bare steel tube and steel tube filled with concrete subjected to axial load.A total of 24 specimens were tested.The main parameter is breadth-to-thickness ratio,which varies from 50 to 125.Also,the finite element software Abaqus was applied to analyze the behavior of hollow steel tube filled with concrete,whose accuracy were validated by comparing with the corresponding experimental results.The results showed that the concrete in the steel tube can increase the buckling bearing capacity evidently with the increase of breadth-to-thickness ratio.

Abstract:The hollow flange beam (HFB) is a particular cross section with two torsion rigid closed triangularflanges and a comparatively flexible web, and it is a type of high efficient cross section. This paper presentstwo kinds of new cold-formed flange-closed welded sections named HF1 and HF2 through change the sectioncomponent and parameters of HFB. Based on the precise finite element model, nonlinear finite elementmethod is adopted to study the static behaviors including buckling modes, deformed process, load carrying ca-pacity and stiffness of two new kinds of section members under axial compression, bend and component axialcompression-bend loads. The two new kinds of section members have some superior static behaviors includinghigher mean section stress and modulus of the member and have no local buckling phenomena in the elementsare proofed under axial compression, and have the well characteristic of high rigidity, high ultimate capacity,local buckling of the sections always hard to occur and correlation curves replete under bend and componentaxial compression-bend loads, too. The new cold-formed flange-closed welded section members can go deepinto the experiment study as to be used in the practical engineering.

Abstract:In order to study the connection method between reinforced bars of the precast concrete structure,based on research results about reinforcement anchorage experiments,108 lapping tests were completed.For the area percentage rate of the lap joints at 100%,the reinforcement lapping length was determined.According to the facts of bars diameter,concrete strength and different lapping length,some specimen simple tensile tests were completed.The failure mode and the impact law of factors about the reinforcement lapping were obtained,and the reasonable length was calculated.Through a series of tests and discussions,the plug-in filling hole for lap-joint of steel bar is a reliable connection,simply construct and suitable for precast concrete structure reinforced connection under the housing industrialization.

Abstract:The effects of different pipe materials and hydraulic conditions on the formation of trihalomethanes(THMs) were investigated.Pipe section reactor was used for the research of pipe materials and dynamic simulation equipment of water distribution network was used for the research of hydraulic conditions.The results of pipe section reactor showed that the ranking of chlorine decay velocity in different pipe materials was ductile cast iron>PVC>stainless steel,while the ranking of THMs concentration was PVC>ductile cast iron>stainless steel.The results of dynamic simulation showed that a higher flow velocity of water caused higher THMs concentration,but it was not distinct compared with the decay of chlorine.When retention time and flow velocity affected the formation of THMs simultaneously,THMs concentration was dependent on the effect degree of the two factors.THMs concentration increased as pipe diameter was increased.Chlorine residual,pipe materials,flow velocity and retention time are all important effects for the THMs formation.

Abstract:In response to sudden phenol pollution accidents,the adsorption performance of activated carbon,carbon fiber,bentonite and fly ash were studied,and the effects of the adsorption time and temperature conditions on activated carbon were studied too.The results indicates that the activated carbon is the most appropriate adsorption material.The adsorption time should be preferably more than 60 min.With the dosage of activated carbon increasing,the removal rate rise rapidly,and then flatten.With the phenol initial concentration increasing,the removal rate decreased slightly.When the sudden phenol pollution accidents occurred in the river,the activated carbon interception and adsorption nets should be set.

Abstract:To better achieve water quality forecast of Songhua River and instruct scientific management of water quality,a water quality forecasting model is set up by ANN technology and is trained by water-quality data from Sifangtai Monitoring Station of the Songhua River.The model could be applied to forecast CODMn that is one of the main pollution indicators in Songhua River.To improve forecasting accuracy,the data is divided into 12 groups and handled by excluding abnormal data based on clustering analysis.At last a test is carried out to verify the effect of clustering analysis,and the results indicate that the clustering analysis in water-quality forecasting model can improve the forecasting effect significantly.

Abstract:Hydrogen-producing acetogens,between acidogenes and methanogens in trophic niche,is very difficult to be separated and only few of the pure cultures have been obtained.This has restricted the development of new anaerobic organic wastewater treatment process with high efficiency based on enhancing their metabolic capability.A new syntrophic acetogen coculture named 7-m-2a which showed great capacity in degrading propionic acid was introduced in this paper.To optimize the culture medium,the influences on 7-m-2a’s growth and metabolism of propionic acid concentration,nitrogen sources,Fe2+,Mg2+,Ca2+ and pantothenic acid were investigated.The results indicated that the suitable concentration of propionic acid and Fe2+,Mg2+,pantothenic acid were 10 g/L and 88,38,30 mg/L,respectively.The optimum nitrogen source was the mixture of yeast extract,tryptone and NH4Cl with a concentration of 0.33 g/L respectively.With the optimization culture,a specific degradation rate of propionic acid and acetic acid yield of 998 mg/(L·d) and 3 947 mg/L,respectively,obtained after fermenting for 30 days at 38 ℃.

Abstract:To reveal the relationship between microorganism and pollutants’ degradation in the stability system of the municipal wastewater treatment plant,the dynamic monitoring of microbial community structure and metabolic activity of the stable operation biological system in biological wastewater treatment plant was carried out using the denaturing gradient gel electrophoresis(PCR-DGGE) and Biolog Technology.The results showed that the average removal efficiency of effluent COD,NH4+-N and TN was more than 84.4%,84.7% and 59.8%,respectively.The microbial community structure was stable in the different sites of biological system in the same season,and the ecological niche of predominant functional species including Bacillus,Pseudomonas,Aeromonas was stable.As the temperature increased in spring,the quantity and diversity of population increased significantly.Meanwhile,metabolic activity strengthened in bioloical system,which could improve the removal rates of pollutants.It is feasible to use the two methods to monitor the changes of microbial community structure of biological system in a wastewater treatment plant at low temperature.

Abstract:The treatment efficiency by the gas-water alternate membrane bioreactor(AMBR) on domestic sewage was investigated through a pilot-scale study in order to get better application effect in the practical engineering.The results showed that: AMBR had good COD and NH4+-N removal effect when the C/N ratio of raw domestic sewage was 4,and the COD and NH4+-N concentration in effluent under 20 mg/L and 5 mg/L.But it’s not good at TN removal because of its low C/N ratio,and the TN concentration in effluent was 22.4 mg/L.When the C/N ratio of raw water increased to 6 according to adding glucose in raw domestic sewage,the TN removal efficiency by AMBR was increased to 66%,and the effluent TN was only 13 mg/L,which met the First A-level requirement of China.Meanwhile,the COD and NH4+-N removal effect by AMBR was unaffected by the change of the raw water’s C/N ration.The trans-membrane pressure was maintained about-20 kPa indicated that AMBR also had good membrane fouling alleviating effect.

Abstract:Desinfection of cooling water system of nuclear plant is the research focus for nuclear power systems.With the circulating cooling water module from Dampierre nuclear plant in France,we study the kinetic of consumption of monochloramine as a desinfect and determine that the consumption of monochloramine with raw water is the first-order kinetic reaction,and the rate constant is 0.002 min-1.The analysis of consumption of monochloramine with Fe3+ added in shows that,the Fe3+ has no significant effect on the consumption of monochloramine.The results can provide technical support and guidance for the design and management of nuclear power plants in China.

Abstract:To obtain the specific influence of urban river on urban thermal climate in summer,fixed-point observation method is used to one-month field measurements in the section of Songhua River Basin in Harbin,and the data collection and analysis on temperature variations from several underlying surfaces and the atmosphere and dynamic thermal budgets have been finished.The results indicate that during the sunny days,ground surface temperature is mostly affected by solar radiation,and it is about 14 ℃ higher than atmosphere temperature above the river,while water temperature is about 3 ℃ lower than atmosphere temperature above the river.Meanwhile,net radiation rate reaches to 700 W/m2,while sensible heat flux and latent heat flux account for a small proportion of net radiation: only 0.2% and 1.8% respectively.The majority of net radiation could be considered to penetrate into the water through heat conduction and transmission while most of which is taken outside city as the river flows during sunny day.During the rainy days,the water temperature is about 2 ℃ higher than atmosphere temperature above the river,and the net radiation is about 100 W/m2,while the proportion of the sensible heat flux and latent heat flux in the whole net radiation is about 9.5% and 51.3%,respectively,which means that the main of net radiation from water surface returns to the atmosphere in the way of convective heat transfer and mass transfer.

Abstract:Although Artificial Neural Network(ANN) shows superior predictive power in the study of quantitative structure-activity relationship(QSAR),it has been labeled as a "black box" because it provides little explanatory insight into the relative importance of the independent variables.In this paper,as an example of toxicity of 35 nitro-aromatics on fathead minnow,six methods which could give the relative contribution and/or the contribution profile of input factors were reviewed and compared.The Partial Derivative method was found to be the most useful as it gave the most complete results,followed by the Profile method that gave the contribution profile of input variables.The Perturb method allowed a good classification of input parameters as well as the Weights method that had been simplified,but these two methods lacked stability.Finally,the classical stepwise methods gave the poorest results.

Abstract:To study the energy utilization of heat pump station for the recovery of waste heat of circulating water in the steam condenser of a coal-fired power plant,the primary energy ratio of the heat pump stations driven by different energy sources for the reclamation of waste heat was analyzed through energy flow diagram.The results show that the electric heat pump energy-supply system consumes 45.79% electricity although the total efficiency of electric heat pump energy-supply system is only 2% lower than that of heat pump energy-supply system driven by steam turbine,as well as approximately equals to that of system driven by gas turbine.Moreover,the situation maybe occurs that the electricity generated by power plant is not enough to its heat pump station with the decrease of the electric generation efficiency and COP of heat pump.By contrast,the primary energy ratio of the heat pump stations driven by steam turbine and gas turbine reaches 1.57 and 1.60,14.77% and 17.00% higher than that of electric heat pump station,respectively,because of introducing the primary energy exteriorly.Therefore,the heat pump stations driven by steam turbine and gas turbine are better than the electric heat pump station in energy utilization.

Abstract:To research the principle of air-source heat pump water unit with energy storage and the application feasibility in this field,the prototype of the hot water unit is developed.Performance of the unit in every mode is studied by experiments.Test results show that the unit can efficiently work in multiple modes,such as heat storage mode,heat and cooling storage mode,hot water supply mode,hot water and chilled water supply mode.Especially,the unit works with higher average energy efficiency ratio in heat and cooling storage mode as well as hot water and chilled water supply mode.In energy storage process,water temperature distribution in hot/chilled water tanks is comparatively uniform,which is favorable for improving the capacity of thermal storage.At the mean time,increasing accumulator volume and debasing location of compressor startup can improve the energy-saving potential and enhance reliability of the unit.

Abstract:Endothermic effects in desorption process of natural gas vehicle tank seriously affects the gas desorption efficiency and vehicle speed.In this paper,a numerical model in desorption process of heating natural gas vehicle tank by engine cooling water was established,and by which the desorption processes were calculated.It shows that when the tank is heated by the engine cooling water,the rising of temperature makes the desorption amount of natural gas increased obviously.Also,the increasing of diameter of internal cooling pipe and thermal conductivity of adsorbent can increase the desorption amount.

Abstract:In order to obtain the CA mortar that can satisfy high-speed railway construction,CA mortar with different proportion was prepared.Through studying strength of CA mortar and Observating its microstructure by scan electron microscopy,the strength and its development of CA mortar was studied by changing sand gradation,the ratio of sand to cement and the ratio of asphalt emulsion to cement.Results show that using combination of two kinds of sand with particle size of 0.15-0.3 mm and 0.3-0.6 mm in CA mortar can reduce the material separation greatly while posing little effect on the 28 d compressive strength of high strength CA mortar.With the increment of m(S)/m(C),the 1 d compressive strength of high strength CA mortar increases but the 28 d compressive strength doesn’t change initially until reaching the critical point 1.4,which drags huge decline for it.The compressive strength of high strength CA mortar of different ages are significantly declining with the increment of m(A)/m(C).Selecting the appropriate size sand,m(S)/m(C) and m(A)/m(C) is the premise to obtain the CA mortar that can satisfy high-speed railway construction.

Abstract:In order to improve the defects of contrast analysis method on automated enforcement effectiveness evaluation in china,in consideration of the influence factors of regression to the mean and traffic management level,a new comprehensive analysis method is given by means of error analysis method in probability theory.It shows that crash effects in our country is greater than that in developed one as a result of automated enforcement,that is,the effects of reducing traffic accidents flowing automated enforcement in China is greater.However,in China,automated enforcement will increase pedestrian hit and the severity of the crash,as well as lead to significant increase the proportion of casualties,which is more obviously different from that in developed country(it only increases the number of rear-end crashes following automated enforcement).The comprehensive analysis method overcomes the defects that contrast analysis method overestimate or underestimate the impacts of automated enforcement in the traffic violations and accidents,it is helpful to promote the application scope and depth of automated enforcement.

Abstract:To solve the acoustic emission(AE) signal de-noising problem,de-noising approaches based on empirical mode decomposition and wavelet transform were proposed,including IMF-Wavelet method,EMD-Wavelet method and Wavelet-EMD method.The standard noise signals and AE signals by pencil lead break were used to analyze the de-noising performance.The simulation results indicate that for the standard noise signals,Wavelet-EMD method has stable de-noising performance whether in high or low signal to noise ratio(SNR) case.Wavelet threshold method is not suitable for AE signal de-noising,EMD-Wavelet and Wavelet-EMD method have stable de-noising performance for AE signals.

Abstract:The scope of this paper addresses the problem of detecting a subpixel moving target from a sequence of multispectral IR cubes.In this work,the detection problem is formulated in a general framework,assuming unknown target amplitude,position and velocity.This composite hypothesis testing problem is approached by means of the generalized likelihood ratio test(GLRT) theory.The detector structure and its actual implementation based on velocity filters are discussed in detail.To test the effectiveness of the detection algorithm,the detection results obtained on a set of synthetic multispectral IR image sequences are presented and discussed,and these results indicate that the algorithm proposed can obtain a good performance on dim target detection with low SNR.

Abstract:With the specially designed large-scale oedometer,routine rheological tests and dry-wet cycle tests have been conducted on specimens to investigate the rheological and dry-wet cycle characteristics of rockfills,which have been widely used in the high-fill foundations of mountain airport.The test results demonstrate that the long term deformation due to dry-wet cycle grows more evidently than the routine rheological deformation,which increases rapidly during early immersion,and gradually flattens after draining the water.There is approximately a logarithmic relationship between dry-wet cycle deformation and cycle numbers.In addition,a simplified coupling calculation method that can meanwhile compute the rheological deformation and dry-wet cycle deformation is proposed,by which the settlement of foundation after construction in X airport of Yunnan Province is computed according to local rainfall law.

Abstract:To evaluate the lifetime performance of prestressed concrete bridges exposed to chloride penetration environment,a probabilistic and finite element-based lifetime performance assessment approach for prestressed concrete bridges is proposed.Firstly,three critical times in the degradation process are discussed and their computing formulas are presented.Secondly,an analysis program named CBDAS(Concrete Bridge Durability Analysis System) is written based on the numerical simulation methods with respect to the deterioration of materials’ mechanical properties,reduction of sectional areas and variation of overall structural mechanics performance.Finally,the assessment method for calculating time-variant system reliability of prestressed concrete bridges is proposed associated with the analysis program CBDAS,Monte-Carlo simulation and analysis technique of the system reliability.The lifetime performance of a prestressed concrete continuous bridge under chloride penetration-induced corrosion is investigated by using the time-variant system reliability.

Abstract:To rapidly and accurately assess the stability of Fujian highway slopes whose tops are composed of soil and foots are of rock,and the partial sliding phenomenon after excavation or after and before support,based on limit equilibrium method,this paper presents a soil and rock mass quality estimation method.For the first time,the soil and rock mass quality estimation were put together to evaluate the slope stability,which expanded the scope of rock mass classification system.One hundred and two slopes along seven highways in Fujian province were used to verify the suitability and accuracy of this method.The soil and rock mass quality estimation method enriches the theoretical system of slope stability,and provides a new approach to the stability assessment of soil and rock slopes.

Abstract:According to the mechanical and structural characters of externally prestressed box girder with corrugated webs,the mechanical performance,such as load bearing mechanism,mechanical characters,damage form and ultimate load capacity of concrete rib deviator used in externally prestressed box girder with corrugated webs is studied using FEA(Finite Element Analysis) and experimental methods.The experimental and FEA results fit each other well.The research indicates that the local influence in concrete flange caused by deviator concentrates in the joints of deviator and concrete flange and the nearby location.When the deviator damages,the tensional concrete cracks and the round reinforcements yield and compressional concrete splits.The compressional concrete shows obvious characteristics of eccentric compression member.The conclusion of this paper may be helpful for designers in designing deviators of externally prestressed box girder with corrugated webs.

Abstract:A research was performed on the numerical simulation and design of cold-formed steel oval hollow section compression members to investigate the applicability of existing design specification to the new section.A non-linear finite element model was developed using Abaqus.The numerical results were compared with the test results and it is shown that the numerical model accurately predicted the structural behavior of the compression members.Parametric study was performed using the verified model including 100 members with different cross-section dimensions and lengths.The test and numerical strengths were compared with the design strengths calculated using the current Chinese Code and direct strength method,which is included by the North American Specification for cold-formed steel structures.It is shown that the direct strength method can be used for the design of cold-formed steel oval hollow section members under axial compression.

Abstract:To improve the scientific management level and effluent quality of a municipal wastewater treatment plant(WWTP),the relationship between the phosphorus removal approach and operating parameters of the A/A/O technology was analyzed by sampling and analyzing samples from the treatment technology process of a WWTP in Beijing,and also the phosphorus material balance was assessed for the sewage treatment system.The results showed that the denitrifying phosphorus removal played remarkably a role for phosphorus removal in the anoxic zone of A/A/O process.The absorption of phosphorus in anoxic zone had exceeded the quantity in the oxic zone.The nitrate concentration in the returned nitrifying liquid had an influence on the denitrifying phosphorus removal.The relationship between phosphorus removal and sludge load,sludge retain time(SRT) showed negative correlation.When the sludge load was about 0.15 kg/(kg·d)and the SRT was about 10-12 d in A/A/O process,the phosphorus removal rate was up to 88%.There was also a negative correlation relationship between the phosphorus accumulation and the sludge emission capacities in the wastewater treatment system.When the sludge emission capacities were controlled to 2.0-2.5 percent inflow of the treatment plant,the phosphorus removal efficiency could be kept on stable and economic status.

Abstract:Allelopathic effects of C.alternifolius(Cyperus alternifolius),M.aquaticum(Myriophyllum aquaticum),C.alternifolius and M.aquaticum were investigated in coexistance experiments,and the algae biomass,chlorophyll a,community change and organic matters of the coexistance samples were monitored and analyzed.Cell numbers and Chl-a were significantly inhibited by C.alternifolius and M.aquaticum.The peak biomass of algae is 2.4×107/L,while that of the control,C.alternifolius,M.aquaticum is 4.48,1.15,2.03×108/L respectively.The organic matters analysis show that only 75 kinds of organic matter exist in the C.alternifolius and M.aquaticum coexistance samples while 131 kinds of organic matter exist in the control sample.Acetone cyanohydrin,Triethyl phosphate,Camphene and 4-methyl-4-Phenol were new produced matters by C.alternifolius and M.aquaticum which maybe the potential allelopathic matters.

Abstract:In order to evaluate the energy-saving effect of seawater source heat pump units over conventional water cooled chillers precisely,various factors that affect the energy consumption of chillers are analyzed.Then a mathematical model of optimal chiller loading was set up on the basis of dynamic programming theory.Through a case study of an office building,the steps of optimal selection of heat pumps or chillers with different capacities are brought out based on the principle that the total energy consumption throughout the cooling season is minimized.And the energy-saving of the seawater source heat pump units in the case project is calculated to be 16.3%.The energy-saving evaluation method of seawater source heat pump units provided in the paper can minimize the calculation error as it is based on the optimal selection of different heat pumps or chillers.

Abstract:In order to improve the ability of the accident prone location identification,the hyperbolic tangent y=a+b×tanh(cx+cd) is proposed as a substitute fitting function of the double exponential function y=a×ebx+c×edx for fitting scatter diagram of accident cumulative frequency.The comparative analysis of the two fitting functions was conducted by simulation analysis and actual data confirmation.The results indicated that the hyperbolic tangent function has higher correlation coefficient in curve fitting,higher detection rate in accident prone location identification,more stable results and better adaptability for the cumulative traffic volume.More significant finding is proposed that the accident number,which decided by cumulative traffic volume in certain accident rate,has very important influence on misdetection rate of accident prone location identification.The hyperbolic tangent can be used for fitting scatter diagram of accident cumulative frequency instead of the double exponential function,and the suggested number of average accident per kilometer should not less than 4 to control the misdetection ratio to about 20%.