• Volume 31,Issue 2,2009 Table of Contents
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    • Parametric Study and Design of the Ultimate Strength of Tubegusset Plate Connections

      2009, 31(2)-7. DOI: 10.11835/j.issn.1674-4764.2009.02.001

      Abstract (9972) HTML (0) PDF 3.02 M (1275) Comment (0) Favorites

      Abstract:The tubegusset plate connections are widely used in electric transmission towers. However, there is little technical information regarding the behavior of tubegusset plate connections. Thus, a analytical parametric study was conducted to investigate the behavior of tubegusset plate connections. The analytical results were compared with the existing experimental results. It was found that the finite element analysis results were in good agreement with the experimental results. In the parametric study, the effects of geometry, chord load and stiffener on the ultimate strength were considered. Based on the analytical results, a design method for predicting the ultimate strength of tubegusset connections was proposed, and its applicability was verified.

    • Linear and Nonlinear Finite Element Analysis of a Degenerated 3D Beam Element

      2009, 31(2):3-7. DOI: 10.11835/j.issn.1674-4764.2009.02.002

      Abstract (10686) HTML (0) PDF 1.53 M (1078) Comment (0) Favorites

      Abstract:In order to solve the calculation problems of the curved beam, an arbitrary crosssection beam and composite beam, a degenerated 3D fiber beam element is derived based on the degenerated theory. According to the basic assumption of plane section, the 3D displacement field equations of an arbitrary point are discretized in terms of nodal displacements, which take account of shear deformation effect. Furthermore, the tangent stiffness matrix formulation, which takes geometric and material nonlinearity into account, is deduced using Update Lagrange formulation. A finite element method program has been developed, and several typical examples are tested to demonstrate the effectiveness, accuracy and versatility of this beam element.

    • Methods of Rock Crack Density Determination and Their Application

      2009, 31(2):5-56. DOI: 10.11835/j.issn.1674-4764.2009.02.003

      Abstract (2908) HTML (0) PDF 1.75 M (2343) Comment (0) Favorites

      Abstract:By the methods of microdamage theory, the relations of rock mass parameters and rock parameters in experiments were obtained; it is considered that to make the microdamage theory for determining the rock parameters possible only in condition that the crack density parameters are obtained reasonably. The methods to determine rock mass crack density have been set up through the intactness index of rock mass and elastic wave equation as well as the geological investigating statistical method, The differences of rock crack density given by these three methods were discussed; based on the statistical data, the Taylor method and generalized selfconsistent method and the Taylor medium method were compared in respect of the influence of crack interaction and the adaptability to the rock parameters . The results show that the reasonable results can be obtained by determining rock crack density from intactness index of rock mass and rock mass parameters by the Taylor medium method.

    • Bending Performance of TubeGusset Joint in Steel Tubular Tower for ExtraHighVoltage Transmission Line

      2009, 31(2):8-22. DOI: 10.11835/j.issn.1674-4764.2009.02.004

      Abstract (3954) HTML (0) PDF 4.68 M (402) Comment (0) Favorites

      Abstract:This paper explored bending performance of tubegusset joint primarily according to experiment and finite element model. The method which is used to determine ultimate strength of the joint was proposed on the base of three joint types including /4 circle ribbed, half circle ribbed and circle ribbed stiffeners. Compared with the Japanese electricity transmitting steel tubular tower manufacture norm, a conclusion has been drawn that the ultimate strength has relationship with several different parameters. The result shows that the ultimate strength of the joint is related not only to the wall thickness t, diameter D, length of gusset plate B and the yield deflection δ at the top of the relevant section under the current status of the region, but also to the ribbed plate. The formula about ultimate strength has important application value for engineering design.

    • Property Analysis of Grids Structures with Random Manufacturing Deviation

      2009, 31(2):8-2. DOI: 10.11835/j.issn.1674-4764.2009.02.005

      Abstract (3441) HTML (0) PDF 4.67 M (338) Comment (0) Favorites

      Abstract:The manufacturing deviation of grids structures was assumed to be in normal distribution, and the normal random sampling was realized by acceptancerejection method. Based on the finite element method and probability method, the initial displacement and stress of grids structures due to manufacturing deviation were analyzed. Numerical example showed that the random manufacturing deviation produced large initial stress, which induced buckling failure of some spatial grid members, and had a large effect on the safety of the grids structures and could not be ignored. It also showed that the method obtained had guiding significance for the design and fabrication of grids structures.

    • Influence of Temperature on the Nonlinear Vibration of Monolayer Cable Net for Pointsupported Curtain Wall

      2009, 31(2):23-28. DOI: 10.11835/j.issn.1674-4764.2009.02.006

      Abstract (3081) HTML (0) PDF 1.57 M (443) Comment (0) Favorites

      Abstract:Taking the temperature effect and geometric nonlinearity into consideration, the nonlinear vibration equation of monolayer cable net for pointsupported curtain wall was derived by assuming the net as a continuum membra. By the Galerkin method, the partial differential equation was transformed into ordinary differential equation which was solved with LP method and KBM method. Taking the monolayer cable net for pointsupported curtain wall of Zhongguancun Culture Building as an example, the effects of temperature, amplitude, initial displacement and exterior excitation on the nonlinear vibration were discussed. The example indicates that the temperature has great influence on the nonlinear vibration of monolayer cable net and the vibration of monolayer cable net for pointsupported curtain wall shows a hard spring characteristic.

    • Mechanical Model with Online Measuring the Cable Tension with “Three Point Bending” Method

      2009, 31(2):29-32. DOI: 10.11835/j.issn.1674-4764.2009.02.007

      Abstract (4366) HTML (0) PDF 1.16 M (2332) Comment (0) Favorites

      Abstract:To set up a mechanical model of threepoint loading for the intellectual measuring equipment of cable tension, the cases for elastic support with two ends of hinged support and those of fixed support with consideration of the influence of the cable were systematically studied. The equations for the upper and lower limits of the cable tension T as well as those for the real measured values have been obtained. A more rational equation for online measuring the cable tension by “Threepoint Bending Method” has been derived through secondary measurement.

    • Research on Seismic Behavior of Frame with Tshaped SRC Columns

      2009, 31(2):33-37. DOI: 10.11835/j.issn.1674-4764.2009.02.008

      Abstract (3168) HTML (0) PDF 2.21 M (1653) Comment (0) Favorites

      Abstract:Referring to the criterion of seismic fortification intensity 8 specified by national seismic design code, a /2scaled model of single span and twostory frame composed of RC beams and Tshaped steel reinforced concrete (SRC) columns has been made. A seismic evaluation was performed by the quasistatic testing, including failure pattern, stiffness degradation, ductility and energy dissipation. The experimental results show that the frame has good seismic behavior, and section steel in the columns plays an important role in earthquake resistance. On the basis of experimental study and analysis, it concludes that the seismic behavior of frame with SRC specialshaped columns can satisfy the requirements of seismic fortification. 

    • Average Constitutional Relationship of Unanchored Zone of RC Structure with Considering Bond and Slip

      2009, 31(2):38-44. DOI: 10.11835/j.issn.1674-4764.2009.02.009

      Abstract (3050) HTML (0) PDF 4.26 M (2006) Comment (0) Favorites

      Abstract:Based on the equilibrium of static forces and coordination of deformations, with considering the effects of bond strength variation and crack width development at different stress stage of reinforcement in tension cracks, the average stress strain relationship of unanchored zone of RC structure under bond and slip action has been derived. The typical test on reinforced concrete beams was simulated with average constitutional relationship and the result was compared with that of real test. The analytical results show that the model using average constitutional relationship with considering bond and slip in unanchored zone of RC structure can give a result close to that of test and simplify the nonlinear analysis.

    • Displacementiteration Formfinding Arithmetic in R Coordinates of ISFSL

      2009, 31(2):45-50. DOI: 10.11835/j.issn.1674-4764.2009.02.010

      Abstract (2406) HTML (0) PDF 2.93 M (1234) Comment (0) Favorites

      Abstract:In order to put the Internal Stretch Forming Space Lattice Structure (ISFSL) into practice, based on the Geometrical Displacementiterative Method, the Displacementiteration Formfinding Arithmetic in R Coordinates is proposed,in which only the displacementiteration is exerted on span coordinates of ISFSL. A detailed study on the formfinding process is carried out, which is based on an ISFSL with a long span of 80m. The result shows that this arithmetic is very simple with great efficiency and working speed. When the sixth iteration is accomplished, the maximal absolute value of error of coordinates is only as follows: ΔR=7.03E-04m, Δθ=6.7E-0°, ΔZ=.04 E-0m,which is satisfied to the engineeringoriented need. The arithmetic also ensures the continuum and integrality of the structural forming and loading analysis, and is quite fit to the formfinding study of ISFSL. 

    • Damage Evolution and Acoustic Emission Character of Coalrock under Unloading Condition

      2009, 31(2):57-61. DOI: 10.11835/j.issn.1674-4764.2009.02.011

      Abstract (2885) HTML (0) PDF 1.85 M (2162) Comment (0) Favorites

      Abstract:The damage failure mechanisms of coalrock under unloading condition during deep mining is different from those under traditional loading condition, starting from the unloading condition position to study the dynamic disaster of coalrock has become a new direction in the disaster study. The rock mechanics electrohydraulic servo test system (MTS815) and acoustic emission system (8CHS PCI2) are used to study the coalrock deformation damage and acoustic emission (AE) characteristics. The results show that the failure of coalrock under unloading condition exhibits strong brittleness and happens in sudden and is mostly of tensileshear failure type. The evolution curve of cumulative ringdown count of acoustic emission can better reflect the coalrock unloading damage evolution process, and the whole unloading failure process can be divided into three stages: the stage of damage weakening, damage stably development stage and the stage of accelerated damage development. During the mining process the confining pressure of the coalrock is unloaded, the coalrock rapidly arrives at the third stage of the whole unloading failure process, and the damage is accumulated rapidly and the fracture failure of coalrok occurred suddenly, then follows the coalrock dynamic disaster.

    • Application of Uncertainty Average Clustering Measurement Model to Classification of Tunnel Surrounding Rock

      2009, 31(2):62-67. DOI: 10.11835/j.issn.1674-4764.2009.02.012

      Abstract (3662) HTML (0) PDF 1.58 M (1710) Comment (0) Favorites

      Abstract:Based on the uncertainty measurement theory, a uncertainty average clustering measurement model for tunnel surrounding rock classification was established. Due to the uncertain factors in judging the engineering quality of rock masses, seven indexes, i.e., the rock grade, rock weathering degree, rock mass structure, elasticity longitudinalwave velocity of rock mass, influence degree of geological structure, development of joint fissure and ground water regime, were used as the discriminating factors. the indexes functions of unascertained measurement of 20 sets of rock samples were established, and the centre of the classification was indicated by using the average of classification of samples. The weight of indexes was calculated by entropy weight theory, and a prediction for the classification of residual tunnel surrounding rock was carried out using the rules of credible recognition. Each of the 20 sets of tunnel surrounding rockmass samples was tested according to the model, and the correctness rate is 100%. The other 10 sets of tunnel surrounding rock samples were predicted by using this model. The results show that the uncertainty measurement model classification agrees well with the actual measured ones. Therefore, it shows that the uncertaity measurement model is effective, available and can be applied to classification of tunnel surrounding rock in underground engineering. 

    • Analysis on Influence of Fault Location and Strength on Deformation and Stress Distribution of Surrounding Rocks of Large Underground Openings

      2009, 31(2):68-73. DOI: 10.11835/j.issn.1674-4764.2009.02.013

      Abstract (3475) HTML (0) PDF 2.75 M (1665) Comment (0) Favorites

      Abstract:The stability of rock mass project is mainly controlled by the rock mass structure, and faults are the large geological discontinuity plane commonly encountered in rock mass engineering. The stability of surrounding rocks is restricted by mechanical property and location to underground cavern of faults, the detailed studies carried out by analysis of numerical calculation and construction monitoring datum of underground powerhouse of Three Gorges Project show: the distribution of stress and deformation of surrounding rock masses containing a fault are badly deteriorated, the distribution of stress and deformation are obviously different under different natural stress field and position of fault; The influence of friction strength of fault on deformation of surrounding rocks is more obvious when a fault is located near the crown, but the cohesion is more when wall nearby, and the influence is more distinct with side pressure coefficient increases.

    • Influence of Construction Defect on the Performance of Lining in Hydraulic Tunnels

      2009, 31(2):74-79. DOI: 10.11835/j.issn.1674-4764.2009.02.014

      Abstract (2762) HTML (0) PDF 2.54 M (1784) Comment (0) Favorites

      Abstract:In the construction of hydraulic tunnel, the engineering quality problem is often caused by concrete cracks and insufficient thickness of roof lining. This problem attracted great attention of the most engineers that whether the structure performance of this kind of lining can meet the design criteria or not, especially under unfavorable conditions. Based on the onsite inspections of the lining defects in Baishanzui tunnels, the model and size of the defects are analyzed with FLAC program. The study shows that the defects have obvious adverse influence on the stability and safety of the tunnel lining, however, if a backfilling grouting is carried out and the cracks are repaired, the integrality of lining is restored, the behavior of lining will be improved and can meet the design criteria as well. 

    • Effect of Microorganisms on Some Engineering Properties of Silt

      2009, 31(2):80-84. DOI: 10.11835/j.issn.1674-4764.2009.02.015

      Abstract (2975) HTML (0) PDF 2.04 M (1778) Comment (0) Favorites

      Abstract:The microbiology was introduced in foundation treatment. Several Carbonatemineralization microorganisms and polysaccharides viscose microorganisms were screened and the microorganisms No.ATCC 6453,3,polysaccharides viscose microorganisms 5 and 6 were used in silt modification. The engineering properties of silt before and after modification were compared by unconfined compressive strength test and indoor seepage test. The microstructures of silt incorporating different microorganisms were analysed by mean of scanning electron microscope and energy dispersive Xray (EDX) analysis. And the modification mechanism of silt has been revealed. These studies indicate that certain engineering properties of silt can be improved by incorporating microorganisms.

    • Improved AHP Assessment Model and Its Practice in Geological Hazard Susceptibility Zoning

      2009, 31(2):85-89. DOI: 10.11835/j.issn.1674-4764.2009.02.016

      Abstract (2612) HTML (0) PDF 1.88 M (545) Comment (0) Favorites

      Abstract:Based on the problem during the practice in geological hazard susceptibility zoning, by constructing the threemark (-1,0,1) matrix and introducing optimum transfer matrix, the faintness about weight choice and the consistency check method of judgment matrix for traditional AHP were improved,and the difficult weight quantization problem for each appraise factor of the hiberarchy model had been solved; accordingly, the Improved AHP model had been built. At the last, this method was applied to a concrete zoning practice about geological hazard susceptibility.The application result shows that the zoning practice in Yongchuan region about geological hazard susceptibility is practical and effective.

    • Combined Network Model for Occupant Evacuation in Building Fires

      2009, 31(2):90-94. DOI: 10.11835/j.issn.1674-4764.2009.02.017

      Abstract (4031) HTML (0) PDF 1.70 M (523) Comment (0) Favorites

      Abstract:Safe evacuation is the most fundamental requirement of fire safety measures in buildings. Many computer based evacuation models have been developed to quantify and model human movement in the buildings. Two methods are usually used to represent the building enclosure in these models: fine and coarse networks. This paper presents a fine network model and a coarse network model based on these methods respectively, and develops an integrated network model that integrates both network methods for efficient and detailed assessment of evacuation in large and complex buildings. To demonstrate the advantages of using the integrated network model, the results of its simulation for a highrise office building and a large shopping mall are discussed and compared to the simulation results of the fine network model and the coarse network model. It shows that the integrated model can be used to simulate evacuation in large and complex building and is adequate in representing details of the evacuation process. 

    • Finite Difference Analysis on Cantilever Slab Model with Void beneath the Cement Concrete Slab Corner

      2009, 31(2):95-99. DOI: 10.11835/j.issn.1674-4764.2009.02.018

      Abstract (2993) HTML (0) PDF 2.09 M (324) Comment (0) Favorites

      Abstract:The advantages and shortcomings of traditional method and Finite Difference Method (FDM) for the calculation of cantilever slab model with void beneath cement concrete slab corner and analysis on the results were carried out. The traditional method assumes that the cement concrete slab with void below was a cantilever slab with constant sections. The influence of loading eccentricity was not considered while more than two wheel loads were exerted on the concrete pavement, which can be overcome by using Finite Difference Method. With FDM, the stress and displacement distributions of any parts of the cement concrete slab can be easily achieved. The results indicate that when the concrete slab with void beneath the slab corner was assumed to be a cantilever slab, regardless of calculation by traditional method or by FDM, the cement concrete pavement will be destroyed even under the condition of minimum traffic grade. The fatigue stress and road deflection obtained by FDM are bigger than that obtained by the traditional formula, so bigger safety factor should be employed in the road design.

    • Evaluating Method of the Coordination Deformation between Asphalt Mixture and Fiber Bragg Grating Sensor

      2009, 31(2):100-104. DOI: 10.11835/j.issn.1674-4764.2009.02.019

      Abstract (3261) HTML (0) PDF 3.03 M (382) Comment (0) Favorites

      Abstract:The study on the coordination deformation between asphalt mixture and Fiber Bragg Grating strain sensor (FBG) is the precondition and foundation to solve the problem of FBG application in pavement. According to the two kinds of FBG developed recently (they were classified into three categories based on the application features), we designed an accuracy evaluation testing method for FBG and asphalt mixture coordination deformation, and conducted the strain test of asphalt mixture by static loading and dynamic loading. The result indicates that using FBG after strain modification to measure the internal stain of the pavement structure is feasible. Compared with other kinds of sensors, module matching FBG has a better test effect, and this kind of FBG is able to reflect the accumulative deformation of asphalt mixture to some extent.

    • Discussion on Calculation Pattern of ConcreteFilled Steel Tube with Dumbbellshaped Section

      2009, 31(2):105-109. DOI: 10.11835/j.issn.1674-4764.2009.02.020

      Abstract (3014) HTML (0) PDF 1.32 M (277) Comment (0) Favorites

      Abstract:Based on the structural feature of dumbbellshaped section of concretefilled steel tube (CFST), a combined spatial beam element is presented. In this structure, two steel tubes, two core concretes, one web and the concrete in web cavity are firstly considered as general spatial beam elements, then they are assembled into a spatial combined beam element according to the plane hypothesis and transformation matrix formed from master and slave nodes. A FORTRAN program for CFST arch with dumbbellshaped section has been developed, and the numerical example shows that the steel tubes and core concretes bear mainly the axial forces with small moments, thus, a modified formula for lattice column method to calculate axial forces of the upper and lower limbs of CFST with dumbbellshaped section is deduced. Comparison of the results from the modified formula with those from an example indicates that the modified formula gives relatively accurate results. 

    • Quantitative Analysis of Influencing Factors for Settlement Generation

      2009, 31(2):110-115. DOI: 10.11835/j.issn.1674-4764.2009.02.021

      Abstract (3666) HTML (0) PDF 2.50 M (388) Comment (0) Favorites

      Abstract:In the research of settlement renovation nowadays, because of the lack of a quantitative analysis, it was difficult to get a scientific, reasonable, systemic quantitative conclusion. This paper is presented to build a scientific,systemic and quantitative analysis method through which many influence factors invloved in the research of settlement, such as physical environment, social behavior and relatoins among these factors were quantitatively analyzed to get a system with generative simulation in the whole and detailed quantitative analysis for each individual factor, and to make the communication and judgement of the result easy. 

    • A Land Use Model for Urban Rail Station Area Planning Based on TOD Strategy

      2009, 31(2):116-120. DOI: 10.11835/j.issn.1674-4764.2009.02.022

      Abstract (5592) HTML (0) PDF 4.02 M (374) Comment (0) Favorites

      Abstract:Transit oriented development (TOD) presents a sustainable urban development strategy by creating an efficient integration of land use and public transit. A TOD planning model for the land use of urban rail station area was explored by means of a multiple objective mathematical programming model. Three objectives were considered: encouraging transit system volume, promoting livable communities, and balancing land use. The model can easily be solved by transforming it into a linear multiprogramming problem. The Xujiahui rail rapid transit station area in Shanghai is chosen as case study to illustrate the model application and planning results. The result indicates that the model would be efficient in practice.

    • The Optimization Method of Biomass Granule Parameter for Pyrolysis Liquefaction

      2009, 31(2):121-125. DOI: 10.11835/j.issn.1674-4764.2009.02.023

      Abstract (3349) HTML (0) PDF 1.81 M (372) Comment (0) Favorites

      Abstract:To make the biomass tablets heated fully in a fluidized pyrolysis liquefaction process, it ought to be ensured that sufficient biomass granules stay long enough in the bed so as to meet or exceed the expected pyrolysis temperature. That is, the prerequisite is that the staying time must be more than or equal to the pyrolysis time. However, the staying time is decided by the flow speed and CFB parameters, and the pyrolysis time is controlled by the heat transfer process of biomass particles in a fluidized bed both of which are closely related to the parameters of biomass particles. This paper analyses the heat transfer process of the biomass in the pyrolysis reaction tower, establishes a simplified model of heat transfer with a gassolid flow, studies the rule of pyrolysis time and staying time changing with the biomass size and finds out a theoretical method of selecting the expected parameters of biomass granule to ensure the full pyrolysis of biomass materials.

    • Comparative Analysis on Experiment about Openloop System and Closeloop System of WSHP at Yangtze River

      2009, 31(2):126-130. DOI: 10.11835/j.issn.1674-4764.2009.02.024

      Abstract (3551) HTML (0) PDF 1.96 M (759) Comment (0) Favorites

      Abstract:Yangtze River is abundant of water and can provide enough water as cooling and heating source for water source heat pumps (WSHP). A pair of contrast experiments with openloop system and closeloop system of WSHP were finished in order to get the heat pump's COP, the system's COP and the distribution of water temperature in the heat exchanger etc. This paper compared the characteristic and the COP of these two kinds of system. The heat pump's COP of the openloop system and closeloop System are 3.08 and 3.77 respectively, and the system's COP are 2.83 and 2.80 respectively. At last, applications of openloop system and closeloop System of WSHP at Yangtze River were analyzed and the key problem for attention was pointed out in the paper. 

    • Atmospheric Environmental Impact Simulation of Gas Fired Boilers as Peak Load HeatSources

      2009, 31(2):131-137. DOI: 10.11835/j.issn.1674-4764.2009.02.025

      Abstract (3219) HTML (0) PDF 3.07 M (339) Comment (0) Favorites

      Abstract:Heating with gas can reduce air pollutant emission and therefore becomes a new sort of peak load heatsource. To study the atmospheric environmental impact, we adopted a newly built combined heating system and simulated its pollutant dispersion for centralized and distributed peak heating. The simulations were based on the improved regulatory environmental impact assessment (EIA) guidelines for atmospheric environment. The model developed an algorithm for infillwinddirection simulation and exported pollutant contours for comparisons. Simulation results show that the system's atmospheric environmental impact is related not only to the pollution emission quantity per quantificational heating, but also to the distribution of heat resource in the gas fired boilers. The centralized peak heating has comparatively small environmental impact; for distributed peak heating, the more concentration of gas fired boilers distribution is applied, the more serious environmental impact will be. In addition, the optimum setting proportion of gas fired boilers should be between 0.2 and 0.6 from the perspective of environmental impact.

    • Adsorption Characteristics of Chestnut Inner Shells to Heavy Metals from Acidic Solution

      2009, 31(2):138-141. DOI: 10.11835/j.issn.1674-4764.2009.02.026

      Abstract (3779) HTML (0) PDF 1.38 M (1764) Comment (0) Favorites

      Abstract:This study reported the feasibility of adsorption of heavy metals from acidic solution using chestnut inner shells (CIS), an environmentallyfriendly natural adsorbent. The adsorption characteristics of CIS for heavy metals were studied by a series of lab scale experiments. The result of adsorption test shows that CIS gives effective removal of heavy metals from acidic solution (pH 2), attaining Cd 98.9%, Pb 99.6%, Zn 98.9%, Cu 98.7% with addition of 30 g/L CIS within 1 h. Thermodynamical test shows that the adsorption capacities of CIS for four kinds of heavy metal are Cd 3.2, Pb 90.8, Zn 27.3, Cu 52.4 mg/g. A kinetic test shows that the adsorption equilibrium is attained within 1 h, and the kinetic behavior of adsorption could be described by Elovich Model. The relationship between the adsorption rate and reaction time is in adverse proportion. At the same time, the adsorption of CIS on Cd, Pb, Cu, Zn is followed by specific order, Pb2+>Cd2+>Cu2+>Zn2+. 

    • Influence of Turbulence Characteristics on the COD and NH3N Degradation Capacity of Activated Sludge System

      2009, 31(2):142-147. DOI: 10.11835/j.issn.1674-4764.2009.02.027

      Abstract (2797) HTML (0) PDF 2.51 M (1135) Comment (0) Favorites

      Abstract:The distribution of turbulence intensity under different rotation speed was analyzed to seek micro indexes reflecting hydraulic conditions of active sludge system by PIV (Particle Image Velocimetry) in a stirring SBR (Sequencing Batch Reactor). Based on the SBR degradation capacity, flocs structure under different rotating speed of stirring paddle, the influences of turbulence intensity on the degradation capacity were studied, and the indexes of turbulence intensity in the main part of stirring zone and other parts were given. The results show that the specified degradation constant of the pollutants in the active sludge reactor increases firstly and then decreases with the increasing of turbulence intensity. The optimum indexes of turbulence intensity in the experiment are 1.4% of main part and 0.34% of other parts. The turbulence intensity indexes in the active sludge system reflect part differences of hydraulic conditions. The turbulence intensity has remarkable influence on the breaking up of active sludge in the main part of stirring zone, while it has good correlation with the collision and gathering of sludge flocs in other parts of the reactor.

    • Life Cycle Assessment System for the Whole Process of Municipal Wastewater Treatment Plants

      2009, 31(2):148-151. DOI: 10.11835/j.issn.1674-4764.2009.02.028

      Abstract (3743) HTML (0) PDF 1.26 M (2480) Comment (0) Favorites

      Abstract:Life Cycle Assessment(LCA) technology is an effective means in determining sewage treatment processes scientifically. This paper uses a sewage treatment process facility as the main line with the application of LCA technology. The Whole Life Cycle of the municipal wastewater treatment plants is divided into three stages:construction stage, operation stage, discarding and removing stage. This paper analyses the whole life cycle of the municipal wastewater treatment plants by the basic framework of LCA. Not only environmental load but also economic and technical factors are contained in the LCA mode. It is demonstrated by the concrete example of two municipal wastewater treatment plants, with evaluating the advantages and disadvantages of the two treatment processes accordingly. 

    • Removal of Oxytetracycline in Water by Improved UV Disinfection Process

      2009, 31(2):152-156. DOI: 10.11835/j.issn.1674-4764.2009.02.029

      Abstract (3170) HTML (0) PDF 1.64 M (2150) Comment (0) Favorites

      Abstract:The removal of oxytetracycline (OTC) in water by UV, UV/TiO2, UV/Zeolite, and UV/Composite photocatalyst with different ratio was investigated respectively with a 32W lowvoltage mercury lamp. The effects of composite photocatalyst concentration, initial OTC concentration and pH value on degradation were also investigated. It was shown that the UV/Composite photocatalyst with 10% TiO2 and 90% Zeolite was an effective one to remove OTC in water. And in a solution with 50 mg/L OTC in ultrapure water the OTC was removed by 99% within 120 min with the help of 300 mg/L composite photocatalyst. The degradation of OTC by UV/Composite photocatalyst was little influenced by its initial concentration, but influenced by its initial pH. In the environment with pH+2~10, the OTC was removed by more than 95% within 120 min with the help of UV/Composite photocatalyst, when the pH is above 10, the removal rate is rapidly decreased. 

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