Abstract:To study the applicability of Newmark integration method for structure with negative stiffness,the method is first investigated,and then the numerical stability of the integration method is analyzed.The influ-ences of Newmark integration parameters,damping and time increment on numerical stability of Newmark inte-gration method are also discussed.The result shows that the integration method,which is very different from the case of positive stiffness,is not unconditional numerical stable in the case of negative stiffness.It is found that the usually used Newmark integration method in the case of positive stiffness with α=1/4,δ=1/2 is dif-ficult to achieve a balance between stability and accuracy because it is stable only when the time increment la-ger than a critical value in the case of negative stiffness.The strategy to obtain numerical stability is proposed by selecting appropriate Newmark integration parameters.This paper presents references for applicability of Newmark integration method and selection of rational integration method when structures with negative stiff-ness.

Abstract:As the aerodynamic forces are inconvenient to be measured in the wind tunnel tests of rain-wind-in-duced vibration(RWIV)of a stay cable under artificial simulation of rainfall,this paper presents a hybrid ap-proach combining experiment and computational fluid dynamics(CFD)numerical simulation for RWIV of a stay cable.The stay cable(including the rivulet)and the flow field are considered as two substructures in the entire system,and the motions of stay cable and rivulet measured through wind tunnel tests are considered as known boundary condition and applied to the flow field.The flow around the moving boundary is then numeri-cally simulated by the Fluent CFD code.First,the feasibility and precision of this approach are verified through the vortex-induced vibration of a circular cylinder,and then the approach is used to study the RWIV of the stay cable.The transient aerodynamic lift and drag coefficients are calculated and applied to a single de-gree of freedom model(SDOF)of the stay cable.The comparison is carried out between the oscillation re-sponses of the SDOF model and experimental results,which indicate that the hybrid approach combining ex-periment and CFD numerical simulation can effectively simulate the transient aerodynamic coefficients of stay cable suffering from the RWIV.

Abstract:In order to fully investigate the influence of statistical uncertainty on reliability of structures,in this paper,the statistical reliability theory of structures considering two kinds of uncertainties,i.e.,physical un-certainty and statistical uncertainty,is deeply and thoroughly studied on the basis of Bayesian statistics.First,the fundamental principles of Bayesian statistics are summarized.The statistical uncertainty in structural engi-neering is then modeled and analyzed by Bayesian updating approach.The various measures for structural sta-tistical reliability are introduced.After that,two methods for statistical reliability analysis of structures consid-ering statistical uncertainty are proposed to treat with the aleatory and epistemic uncertainties:the integrated approach and the separate approach.Two examples are given,one of which is a numerical one;the other is a fracture reliability problem.The examples demonstrate the influence of statistical uncertainty on the reliability indices of structures.

Abstract:To study the deformation performance of composite beam in whole structure subjected to fire,we have carried out two fire experiments of composite beams considering different working conditions in whole structure.The furnace temperature and the temperature of different points in the same section were measured,as well as the vertical deformations at different sections were detected during the experiment.The results showed that:in the fire tests,the composite beams across the same section had a big temperature gradient,which generated thermal stress.However the composite beams couldn’t deform freely because of adjacent components,the vertical deformation of composite beam began to recover in the warming phase and was up-ward finally;The fire behaviors of different composite beams in whole structure was different.Exposed com-posite beam in whole structure shows the good fire resistance.

Abstract:To study the seismic behavior of RCRC ultra short columns,the tests subjected to combined con-stant axial compression and cyclic lateral shear force of rectangular tubed RC(RTRC)columns including 4 RCRC and 2 common RC columns for comparison were carried out.The main parameters were axial load ratio(0.3 and 0.5)and width to thickness ratio(111 and 166),and the shear span to depth ratio of all the tested columns was 1.0.The results indicated that the failure mode of common RC short columns was shear failure,therefore the RC columns showed little ductility and energy dissipating capacity.Under lateral shear force,RCRC short columns showed no shear failure due to the effective confinement from the outer tube to the core concrete.The RTRC columns showed higher ductility,elastic-plastic deformation capacity and energy dissipa-ting capacity than the common RC columns.The lateral load strength of RCRC short columns increased with the increment in axial load ratio,while the ductility decreased a little,and the width to thickness ratio affected little on the seismic behavior of RTRC ultra short columns.

Abstract:Fire dynamics,heat transfer and finite element analysis method were used to obtain the fire resist-ance of airport terminal steel structure.First,the credible and most dangerous fire scenarios of airport terminal roof were adopt.Then,the fire dynamics software FDS and the heat transfer formula were used to get the tem-perature rise curves in the fire affected region.Finally,the model of the structure was set up by finite element method,the load conditions and temperature rise curves were combined to calculate the mechanical properties of the structure.The resulit shows that the internal force of some members in the structure are increased and e-ven close to the design strength,but the vertical displacement of the structure is relatively small to the overall span of the structure,the structure is still in safe condition.From the perspective of overall security,it is effi-cient to carry out the fire-resistant design of structure by its own strength,and to improve the fire-resistant properties of the structure by strengthening the integrity and increasing the number of statically indeterminate.

Abstract:To investigate the feasibility of hybrid membrane process for treating micro-polluted water,the treatment of micro-polluted reservoir water from Huanghe river,which presented low turbidity and low temper-ature were carried out,and the submerged membrane bioreactors without(MBR)and with(PAC-MBR)pow-dered activated carbon(PAC)were evaluated for drinking water production,while the fouling mechanism of the two membrane were discussed too.Both of the MBR and PAC-MBR guaranteed the turbidity removal a-bove 97%.The ability of organic substances removal were:PAC-MBR>MBR>conventional process>ultra-filtration(UF)alone.No effect of UF alone on NH 3-N removal was observed,while PAC-MBR and MBR gave an average removal rate of 73.39%and 65.01%,respectively.By comparing the trans-membrane pres-sure(TMP)trend of two bioreactors,it could be concluded that activated sludge,with PAC as a carrier,showed higher activity and better filterability than the activated sludge naturally formed,and PAC-MBR ap-peared a slower membrane fouling.

Abstract:To evaluate the suitable sludge retention time(SRT)in submerged membrane bioreactor(SMBR) for drinking water treatment,two SMBRs under the SRT of 80 d and 20 d were run in parallel and compared in terms of the effectiveness for treating polluted raw water.The results showed that under the SRT of 80 d,the removal efficiencies of SMBR for DOC,UV 254,TOC,COD Mn were 19.6%,13.4%,27.7%and 30.7%,while those under the SRT of 20 d were 21.2%,13.2%,29.2%and 32.7%,respectively.Furthermore,both of the SMBRs achieved over 96%of removal for influent NH3-N.However,when the short SRT(20 d) was employed,the development rate of trans-membrane pressure in SMBR was lower than that under long SRT(80 d).Therefore,the reduction of SRT from 80 d to 20 d would not affect the effectiveness of SMBR for treating polluted raw water,but mitigate the membrane fouling in SMBR.With the short SRT,it would be possible to dose powdered activated carbon directly in the SMBR,in which the sludge withdrawal could be performed periodically,to maintain the sludge concentration in suitable range.

Abstract:A static experiment was carried out to evaluate trace cadmium(Ⅱ)removal from water by two kinds of manganese coagulants,hydrous manganese dioxide(HMO)and ferric manganese coagulant(HFMO).The effects of turbidity,initial concentration of cadmium,coagulation time and different waters on the cadmium removal were investigated.The results showed that both HMO and HFMO could eliminate cadmium quickly from water,and the effectiveness of cadmium removed by HMO was better than that by HFMO.When pH=6.72,the Cd(Ⅱ)initial concentration was 1 mg/L and the dosage of HMO was 20 mg/L,the re-moval rate of cadmium reached 85.04%.As for HFMO,when pH=8.03,the removal rate of cadmium was only 53.23%.HMO performed better than HFMO on removal of cadmium and turbidity,when two manganese coagulants were used to treat the raw water of Jingmi canal of Beijing.

Abstract:During bioenhanced activated carbon(BEAC)process,the inoculated bacterial communities are dynamic.For solving this problem,bacteria with biodegradability and competitive power must be isolated.DGGE profiles of BAC filter indicated that there were 4 dominant bacteria,and 2 of them could degrade organ-ic pollutants,which were Pseudomonas sp.and Bacillus subtilis.Thirty five bacteria were isolated from BAC filter using LB medium.Target probe of Pseudomonas sp.and Bacillus subtilis were designed for testing domi-nant bacteria quickly.After fluorescence in situ hybridization(FISH),5 dominant bacteria were identified and they were SRO 2(Pseudomonas stutzeri),SRO 11(Pseudomonas putida),SRO 19(Pseudomonas pertucinogena),SRO 20(Pseudomonas balearica)and SRO 30(Bacillus subtilis),respectively.The biodegradation test of organic pollutants in Songhuajiang water showed that the 5 bacteria could degrade organic pollutants.Dehydrogenase activities in these 5 bacteria were higher than other isolates,so that these five bac-teria were valuable bacterial resource for applying in BEAC process.

Abstract:To improve the pollutant removal efficiency of anaerobic baffled reactor(ABR),the influence of or-ganic loading rate(OLR)on the treatment system was investigated based on adjustment of influent COD con-centration and hydraulic retention time(HRT).The available volume of the ABR was 28.75 L.The results indicated that the adjustment of influent COD and HRT with the OLR ranged from 4 to 5.4 kg·m-3 ·d-1 could make all kinds of function flora that participated the anaerobic digestion process distribute more orderly in the ABR system,and the pollutant removal efficiency and the stability of the reactor were improved effec-tively.A COD removal rate above 90%can be achieved in the ABR when OLR is 4 kg·m-3 ·d-1,the in-fluent COD is 8 000 mg·L-1 and HRT is 48 h.

Abstract:To investigate the mechanism of simultaneous nitrification and denitrification(SND)and promote the efficiency of SND system,by using the domesticated efficient SND sludge,the effects of organism,DO and temperature on the SBR reactor were studied.The experiment results showed that,when the temperature was 25-30 and pH was 7-9,the nitrate-nitrogen removal was preferably;when C/N rate varied between 1:1-8:1,COD concentration,ammonia nitrogen removal rate and TN removal rate decrease with the increasing of C/N rate.Dosing organic compounds in twice can enhance the aerobic denitrification effect.When aeration volume varied from 0.12 to 0.80 L·min-1,ammonia nitrogen removal rate increased first and then kept ap-proximate constant with the increase of aeration volume,finally became stable at 99.8%.TN removal rate in-creased first to the highest at 95.52%,then decreased,when aeration volume was 0.2 L·min-1,and COD was stable above 91%.The influence of aeration rate on the COD removal is not distinct.The best effect will be achieved if the system temperature is 25-30℃,C/N rate is 1.5:1,aeration volume is 0.2 L·min-1,pH is 7-9 and the dosing of organic compounds is in twice.

Abstract:The use of microbial de-emulsifier is limited for its low de-emulsification activity,instability and sen-sitivity to environmental factors.To solve this problem,two superior strains(Bacillus mojavensis,Bacillus subtilis)were cultured in a mineral salt medium to obtain a microbial compound de-emulsifier with high capa-bility of de-emulsification.The cell culture could demulsify the O/W model emulsion completely in 48 h at room temperature.Comparing with that of the single strain culture,the fermentation process of the mixed culture was shortened more than 6 h.With less addition volume,the mixed culture showed higher de-emulsification activity and stability.The microbial compound de-emulsifier kept high de-emulsification activity in the emulsion with different pH value ranged from 3-7.Thermostability was detected.When the emulsion temperature varied from 20-120℃,changing rate of the oil drain rate was under 15%.After the strains were mixed cultured,the me-tabolites produced during the fermentation process still took the main function of de-emulsifiction.The superna-tant remained 87%de-emulsification ability of the cell culture while the bacterial cells could hardly break the e-mulsion.Comparing with the widely used chemical ones,the microbial compound de-emulsifier has almost the same effectiveness in dealing with the oil-bearing waste water from Daqing oilfield.Compounding microbial de-e-mulsifiers is an effective way to enhance their demulsification abilities.

Abstract:To improve the analysis ability of residue levels of persistent toxic substances(PTS)in environ-ment,this paper investigated the distribution characteristics of air concentrations of polycyclic aromatic hydro-carbons(PAHs)during the Spring of 2007(January to April)in 4 different functional areas(urban,subur-ban,rural,and remote areas)in and near the Harbin metropolitan by using the fuzzy C-means clustering al-gorithm,and got the cluster centers of different samples and a membership matrix which offered quantity foun-dation for analysis of samples description.Results showed that the contamination level in the urban industrial area was the highest,followed by those in the other urban places and rural area,and the contamination levels in the remote area and in the places on the windward were the lowest.PAHs in Harbin urban atmospheric were mainly from coal-burning and industrial emissions,those in rural areas were mainly from the burning of crop stalks.PAHs in air in this region have imposed a potential threat on human health.

Abstract:As a special form of pollution emissions,the fumigation gas of CH 3-Br discharged by log in train causes serious damage to the nervous system and respiratory system of human and animals.This paper took Tongjiang log fumigation site for example,selected body source model of AERMOD to simulate the diffusion of fumigation pollution and analyzed the impact of pollution.Results showed that high concentration of CH3-Br was centered in the surroundings of fumigation lines and most occurred at night.The farther away from the fu-migation line,the lower the excess standard rate of CH 3-Br.With the prediction and the calculated maxi-mum distance,pollution control measures were proposed for the fumigation field.

Abstract:Based on mathematical simulation method,an optimization scheme of aeration system was proposed to save energy,which reduced the number of running aeration brush from 5 to 4 in the middle ditch under the normal operation condition.When the increasing degree of inflow was over 25%or the substrate concentration above 50%,the number of running aeration brush would be increased to 5.When the inflow were lower than normal condition,the number would be decreased to 3.With implementing this scheme for two months,the water quality of effluent could always meet the first class of B standard.

Abstract:Based on the introduction of Nusselt’s model,this paper reviewed the theoretical progress of lami-nar film condensation on single horizontal integral-finned tubes.Firstly,the Nusselt’s laminar film condensa-tion theory for single horizontal smooth tube and its experimental verification was introduced.Secondly,the mechanism of film condensation enhancement on two-dimensional(2D)surface was analyzed based on the stress analysis of condensation film that generated on the 2D fin surface.Finally,the vital models for film con-densation on 2D fined tubes and consistency check of them with experimental results were introduced in detail.The overview shows that the theoretical model for laminar film condensation on one-dimensional surface has been well established,and semi-empirical models for laminar film condensation on traditional 2D surface have been built up,but not yet completed.Effect of curvature change induced by 2D fin structure and the rough-ness of the fin surface on film condensation should be considered when more accurate semi-empirical model is needed.In order to complete the theoretical model for 2D surfaces and build theoretical model for 3D sur-faces,more efforts on mechanism analysis and accurate experiments should be made.

Abstract:For evaluating the reliability of topology of district heating network,connectedness between heat sources and heat users was proposed based on spatial network model.Four indices of connectedness reliability were established to describe heat supplying from heat sources and heat flowing into heat users.The connected-ness importance of pipe was then put forward on the basis of the connectedness reliability from all heat sources to all users.The connectedness reliability of heating network with multi-sources and multi-loops was analyzed,as well as the connectedness importance of pipes on main pipelines,loops and common pipelines.Analysis shows that the connectedness reliability of heating network with multi-sources and multi-loops was considera-ble.The closer the distance between pipe and source,the higher the connectedness importance of pipe.The length of the main pipe is important to the system reliability.

Abstract:Based on the field data collected from a medium-scale experimental pavement system,temperature distribution characteristic of subgrade in seasonally frozen regions was studied in detail,and the prediction model for subgrade temperature distribution was proposed with regression analysis.Test data illustrated that:The temperature of subgrade changed with time,and it followed cosine distribution;Energy was stored with the heat transfer in subgrade,and it transferred nonlinear with depth.Based on the collected data,the prediction model for subgrade temperature distribution in this area was proposed.The comparison between measured and predicted temperatures indicated that this model had good applicability and accuracy for this area.

Abstract:To analyze the relative management strategies during regional evacuation and traffic management and the relationship among them,from the global perspective of disaster emergency management,this paper i-dentifies the types,stages of disaster management and major traffic management issues involved during the process of disaster management.Also,the connotation and extension of regional evacuation traffic management are clarified.Finally,a integrated modeling and analysis framework of evacuation traffic management is estab-lished,including the disaster scenario analysis,evacuation traffic demand forecasting,evacuation traffic flow analysis,evacuation traffic dynamic assignment model,integrated evacuation traffic management and simula-tion evaluation of evacuation traffic management plan.This framework can effectively guide the analysis and modeling of regional evacuation traffic management issue and present a significant theoretical and practical val-ue for improving the efficiency of traffic evacuation in a transportation network.

Abstract:Based on the giant magneto-impedance principle of amorphous materials,a novel magnetic sensor is presented and developed.According to double peaks feature of the amorphous,the working principle is ana-lyzed.The sensor structure with closed loop negative feedback is designed,and the mathematical model of the sensor is deduced.By analyzing the error transfer function of the sensor,PI controller is proposed,which can e-liminate the steady state error and improve the linearity.The experimental results show that the performance of the sensor is improved by PI controller.The linearity is within 0.2%and the sensitivity is up to 1.759 V/Oe.

Abstract:A tri-level Nested Logit choice model was developed to optimize regional transportation corridors al-location.From the perspective of users and by applying hierarchical ideas,uncertain programming theory and random utility theory,the traffic mode choice in corridors was discussed.Taking Beijing-Shanghai transporta-tion corridor for instance,the model parameters were calibrated by using the Beijing-Shanghai maglev transit passenger forecast survey and other supplementary traffic survey data,and the rationality of the model was vali-dated.Results show that the model could overcome the defects of Multinomial Logit Model and be a promising approach to improve the structure configuration of transportation modes in regional transportation corridors.

Abstract:The conventional eigen value analysis method(CEVA)has some shortcomings in solving two-di-mensional coupled flutter problems,for example,when the frequency ratio of torsional to bending is approac-hing 1,the pre-selection of frequency and its iteration is a time consuming work.This paper presents an straight forward method for analyzing two-dimensional coupled flutter of super-long-span suspension bridges,u-tilizing CEVA method and Ferrari’s thoughts on solving univariate equations of four degrees,which has both improvements on work process and work time compared with the CEVA method.Case studies of four different cross section suspension bridges(the ideal plate,close steel box,single slotted steel box,and double slotted steel box)are provided to validate the developed procedure as well as to demonstrate the flutter analysis of su-per-long-span suspension bridges using straight forward method.The proposed method in this paper enables the researchers to make comparison on the flutter modality,flutter stability performance and freedom coupling extent of suspension bridges with different mid-span and different cross sections.

Abstract:To solve current stiffness problems of long-span cable-stayed bridges,a new cable-stayed bridge with carbon fiber reinforced polymer(CFRP)and steel composite stay cables was proposed.Firstly,the de-sign strategies and procedures for the proposed cable-stayed bridges were introduced.The equations to calcu-late the material amounts and costs of the proposed cable-stayed bridges were also derived.By doing this,the economic behaviors of the composite bridges,which were the emphasis of this paper,were then studied.A parametric study with regard to span length,pylon height,and cost ratio(the cost ratio of CFRP stay cables to steel stay cables)was finally conducted,which determined the developing trend of economic behaviors.It is proved in this study that the application of CFRP and steel composite stay cables in cable-stayed bridges is fea-sible from the economic viewpoint and the proposed composite cable-stayed bridges could become an excellent alternative to the traditional cable-stayed bridges in the future.

Abstract:A new wavelet energy transfer function spectrum(WETFS)method was proposed in this study to remove frequency contamination of earthquakes from wavelet spectrum of structural responses in identifying fre-quency variation of structures.First,wavelet spectrums of earthquake excitation and structural response were integrated along time respectively to get wavelet energy spectrum of earthquakes and seismic responses.Then the WETFS was defined by dividing wavelet energy spectrum of earthquake excitation by that of structural re-sponse.The ridge on WETFS just represented the variation of structural frequencies.This method and the tra-ditional wavelet method were both applied on frequency identification of one 6-story masonry apartment build-ing.The seismic responses of this building during series of aftershocks of Wenchuan earthquake were measured and structural frequencies were identified to decrease remarkably during two aftershocks.The results of the two methods indicate that the WETFS method can identify variation of structural frequency accurately without con-tamination of earthquake excitation.

Abstract:To study the contamination distribution in a chamber with perforated ceiling air supply,simulative analysis and experimental tests are carried out in this paper.In modeling,the Basic model and N-spot air model are both used for defining the orifice entrance boundary condition.The simulation results show that the distribution of contamination concentration agrees well with the test result.Especially,the simulation result of the N-spot air model is closer to the experimental one,which proves the feasibility of this model in analyzing indoor contamination distribution.

Abstract:To study the seismic response of floating roof storage tank with the base isolation,the floating roof is assumed as a homogeneous rigid circular plate,the vibration form of wave height is assumed as linear distribu-tion along the radius.By the velocity potential theory,the velocity potential function of the liquid movement and the expression of base shear and overturning moment are established and by the plate vibration theory and energy principle,the motion equation for the floating roof and the motion equation for the tank system are pres-ented,respectively.With the time history analysis,the seismic responses for the isolated floating roof storage tanks are studied.The numerical results show that the fundamental frequency of isolation is applicable to be 2-3 rad/s,while the damping ratio of isolation is 0.1.The damping rates ofⅠ,Ⅱsite are better than those of Ⅲ,Ⅳsite.The effects of different sites on wave height are different,and the ratio of height to diameter has little effect on the seismic response of the isolated floating roof storage tanks.

Abstract:To study the volatile oil of Korean Epimedium Nakai,it is extracted by accelerated solvent extraction(ASE),and then identified by gas chromatography-mass spectrometry(GC/MS).In the completely random-ized design optimization of extraction conditions ASE,the extraction yield of volatile oil is 4.0%,by retrieving NIST 98 spectrum library,91 of them were confirmed.With peak area normalization method,the chemical in-gredients in the relative content of volatile oil were obtained.The result is that the main constituents of Korean Epimedium volatile oil are:4,4a,5,6,7,8-2(3H)-naphthalene-one;1,2-benzene dicarboxylic acid;10hydrogen-4a-methyl-1-naphthalene;N,N’-2(1-methyl)-1,4-phenylenediamine;-butyl-1,2-phenyl bicy-clic 2-carboxylic acid;two decanoic acid ethyl ester.