Recycled waste tires when mixed with soil can play an important role as lightweight materials in retaining walls and embankments, machine foundations and railroad track beds in seismic zones. Having high damping chara...Recycled waste tires when mixed with soil can play an important role as lightweight materials in retaining walls and embankments, machine foundations and railroad track beds in seismic zones. Having high damping characteristic, rubbers can be used as either soil alternative or mixed with soil to reduce vibration when seismic loads are of great concern. Therefore, the objective of this work was to evaluate the dynamic properties of such mixtures prior to practical applications. To this reason, torsional resonant column and dynamic triaxial experiments were carried out and the effect of the important parameters like rubber content and ratio of mean grain size of rubber solids versus soil solids(D50,r/D50,s) on dynamic response of mixtures in a range of low to high shearing strain amplitude from about 4×10-4% to 2.7% were investigated. Considering engineering applications, specimens were prepared almost at the maximum dry density and optimum moisture content to model a mixture layer above the ground water table and in low precipitation region. The results show that tire inclusion significantly reduces the shear modulus and increases the damping ratio of the mixtures. Also decrease in D50,r/D50,s causes the mixture to exhibit more rubber-like behavior. Finally, normalized shear modulus versus shearing strain amplitude curve was proposed for engineering practice.展开更多
The present paper intends to introduce a new method for reducingbends erosion from particles impacts: the ribbed bend erosionprotection method. Ribs are evenly fixed in the range of 20 deg-80deg on the inner-wall of i...The present paper intends to introduce a new method for reducingbends erosion from particles impacts: the ribbed bend erosionprotection method. Ribs are evenly fixed in the range of 20 deg-80deg on the inner-wall of inside 90 deg bend and the bend (includingribs) is made of medium carbon steel. Three-dimensional numericalworks is performed and the result shows satisfactory agreement withthe experimental measurement. Numerical simulation studies thecharacteristics of axial gas flow along the bend and secondary flowat cross section.展开更多
For solving the optimization model of earthwork allocation considering non-linear factors,a hybrid algorithm combined with the ant algorithm(AA)and particle swarm optimization(PSO)is proposed in this paper.Then the pr...For solving the optimization model of earthwork allocation considering non-linear factors,a hybrid algorithm combined with the ant algorithm(AA)and particle swarm optimization(PSO)is proposed in this paper.Then the proposed method and the LP method are used respectively in solving a linear allocation model of a high rockfill dam project.Results obtained by these two methods are compared each other.It can be concluded that the solution got by the proposed method is extremely approximate to the analytic solution of LP method.The superiority of the proposed method over the LP method in solving a non-linear allocation model is illustrated by a non-linear case.Moreover,further researches on improvement of the algorithm and the allocation model are addressed.展开更多
Decreasing in emissions of greenhouse gases to confront the global warming needs to replace fossil fuels as the main doer of the world climate changes by renewable and clean fuels produced from biomass like wood waste...Decreasing in emissions of greenhouse gases to confront the global warming needs to replace fossil fuels as the main doer of the world climate changes by renewable and clean fuels produced from biomass like wood waste which is neutral on the amount of CO2. An analytical and engineering model for pyrolysis process of a single biomass particle has been presented. Using a two-stage semi global kinetic model which includes both primary and secondary reactions, the effects of parameters like shape and size of particle as well as porosity on the particle temperature profile and product yields have been investigated. Comparison of the obtained results with experimental data shows that our results are in a reasonable agreement with previous researchers' works. Finally, a sensitivity analysis is done to determine the importance of each parameter on pyrolysis of a single biomass particle which is affected by many constant parameters.展开更多
A real-time Diesel Particulate Matter （DPM） monitor has been developed on the base of the successful National In- stitute of Occupational Health and Safety （NIOSH） designed Personal Dust Monitor （PDM） unit. The ...A real-time Diesel Particulate Matter （DPM） monitor has been developed on the base of the successful National In- stitute of Occupational Health and Safety （NIOSH） designed Personal Dust Monitor （PDM） unit. The objectives of a recently completed Australian Coal Association Research Program （ACARP） study was to modify the PDM to measure the submicrometre fraction of the aerosol in a real-time monitoring underground instrument. Mine testing focused on use of the monitor in engineering evaluations of Longwall （LW） moves demonstrated how DPM concentrations from vehicles fluctuate under varying ventilation and operational conditions. The strong influence of mine ventilation systems is reviewed. Correlation between the current SKC DPM measurement system and real-time DPM monitors were conducted and results from eight mines show a correlation between elemental carbon （EC） and the new monitor DPM mass ranging from 0.45 to 0.82 with R2〉0.86 in all but two cases. This differences in suspected to be due to variations from mine to mine in aspects such as mine atmospheric contamination, vehicle fleet variations, fuel type, engine maintenance, engine combustion efficiency, engine behavior or interference from other submicrometre aerosol. Real-time monitoring clearly reflects the movement of individual diesel vehicles and allows pin-pointing of high exposure zones such as those encountered where various vehicles engage in intense work in areas of constrained or difficult ventilation. DPM shift average monitoring approaches do not readily allow successful engineering evaluation exercises to determine acceptability of pollution levels. Identification of high DPM concentration zones allows efficient modification of mine ventilation, operator positioning and other work practices to reduce miners＇ exposures without waiting for laboratory analysis results.展开更多
In a lab of the CAS Institute of Process Engineering（IPE）in Beijing,Winifred Uduak Anake,a visiting woman scientist from Covenant University.Nigeria was dashing to finish testing the 100 plus samples she collected f...In a lab of the CAS Institute of Process Engineering（IPE）in Beijing,Winifred Uduak Anake,a visiting woman scientist from Covenant University.Nigeria was dashing to finish testing the 100 plus samples she collected from her home country.＂1 am trying to find out the type and amount of hazardous trace metals bound to the tiny particles trapped on the filters,＂she explained：＂out of worries about their possible threat to human health.＂Before concluding her three-month stay she needed to complete examining the morphology of the particles,total trace metals,展开更多
Particulate emission is a major problem in industrial processes, mainly power plants that make use of coal as a primary source of energy. Stringent emissions limits, set by government organisations requires industries...Particulate emission is a major problem in industrial processes, mainly power plants that make use of coal as a primary source of energy. Stringent emissions limits, set by government organisations requires industries to conform to these limits to ensure that air quality is sustained and with minimum pollutant present. Electrostatic precipitators are typically used to filter and collect these particulate emissions. Fly ash resistivity is a primary parameter in the collection of particulate emissions, and there is a resistivity range at which electrostatic precipitator collection is most efficient and anything outside this range limits, their operation. High resistivity ash results in back-corona discharge, whilst low resistivity results in particle re-entrainment into the flue gas stream. The purpose of this paper is to investigate and obtain a fly ash resistivity profile for existing power plants in South Africa. Ash samples obtained from power plants are, tested making use of an ash-resistivity test oven, in accordance with IEEE Standard 548-1984. This paper discusses obtained experimental results, to determine the resistivity profile at which South African power plant electrostatic precipitators operate. The electrical efficiency of the electrostatic precipitator system is evaluated based on the obtained resistivity profiles.展开更多
文摘Recycled waste tires when mixed with soil can play an important role as lightweight materials in retaining walls and embankments, machine foundations and railroad track beds in seismic zones. Having high damping characteristic, rubbers can be used as either soil alternative or mixed with soil to reduce vibration when seismic loads are of great concern. Therefore, the objective of this work was to evaluate the dynamic properties of such mixtures prior to practical applications. To this reason, torsional resonant column and dynamic triaxial experiments were carried out and the effect of the important parameters like rubber content and ratio of mean grain size of rubber solids versus soil solids(D50,r/D50,s) on dynamic response of mixtures in a range of low to high shearing strain amplitude from about 4×10-4% to 2.7% were investigated. Considering engineering applications, specimens were prepared almost at the maximum dry density and optimum moisture content to model a mixture layer above the ground water table and in low precipitation region. The results show that tire inclusion significantly reduces the shear modulus and increases the damping ratio of the mixtures. Also decrease in D50,r/D50,s causes the mixture to exhibit more rubber-like behavior. Finally, normalized shear modulus versus shearing strain amplitude curve was proposed for engineering practice.
基金Supported by the National Natural Science Foundation of China (No. 29876034).
文摘The present paper intends to introduce a new method for reducingbends erosion from particles impacts: the ribbed bend erosionprotection method. Ribs are evenly fixed in the range of 20 deg-80deg on the inner-wall of inside 90 deg bend and the bend (includingribs) is made of medium carbon steel. Three-dimensional numericalworks is performed and the result shows satisfactory agreement withthe experimental measurement. Numerical simulation studies thecharacteristics of axial gas flow along the bend and secondary flowat cross section.
文摘For solving the optimization model of earthwork allocation considering non-linear factors,a hybrid algorithm combined with the ant algorithm(AA)and particle swarm optimization(PSO)is proposed in this paper.Then the proposed method and the LP method are used respectively in solving a linear allocation model of a high rockfill dam project.Results obtained by these two methods are compared each other.It can be concluded that the solution got by the proposed method is extremely approximate to the analytic solution of LP method.The superiority of the proposed method over the LP method in solving a non-linear allocation model is illustrated by a non-linear case.Moreover,further researches on improvement of the algorithm and the allocation model are addressed.
基金Project supported by the National Natural Science Foundation of China(Nos.41271484 and 41261079)the Fujian Provincial Natural Science Foundation of China(Nos.2013J01166 and 2012J05030)
文摘Decreasing in emissions of greenhouse gases to confront the global warming needs to replace fossil fuels as the main doer of the world climate changes by renewable and clean fuels produced from biomass like wood waste which is neutral on the amount of CO2. An analytical and engineering model for pyrolysis process of a single biomass particle has been presented. Using a two-stage semi global kinetic model which includes both primary and secondary reactions, the effects of parameters like shape and size of particle as well as porosity on the particle temperature profile and product yields have been investigated. Comparison of the obtained results with experimental data shows that our results are in a reasonable agreement with previous researchers' works. Finally, a sensitivity analysis is done to determine the importance of each parameter on pyrolysis of a single biomass particle which is affected by many constant parameters.
文摘A real-time Diesel Particulate Matter （DPM） monitor has been developed on the base of the successful National In- stitute of Occupational Health and Safety （NIOSH） designed Personal Dust Monitor （PDM） unit. The objectives of a recently completed Australian Coal Association Research Program （ACARP） study was to modify the PDM to measure the submicrometre fraction of the aerosol in a real-time monitoring underground instrument. Mine testing focused on use of the monitor in engineering evaluations of Longwall （LW） moves demonstrated how DPM concentrations from vehicles fluctuate under varying ventilation and operational conditions. The strong influence of mine ventilation systems is reviewed. Correlation between the current SKC DPM measurement system and real-time DPM monitors were conducted and results from eight mines show a correlation between elemental carbon （EC） and the new monitor DPM mass ranging from 0.45 to 0.82 with R2〉0.86 in all but two cases. This differences in suspected to be due to variations from mine to mine in aspects such as mine atmospheric contamination, vehicle fleet variations, fuel type, engine maintenance, engine combustion efficiency, engine behavior or interference from other submicrometre aerosol. Real-time monitoring clearly reflects the movement of individual diesel vehicles and allows pin-pointing of high exposure zones such as those encountered where various vehicles engage in intense work in areas of constrained or difficult ventilation. DPM shift average monitoring approaches do not readily allow successful engineering evaluation exercises to determine acceptability of pollution levels. Identification of high DPM concentration zones allows efficient modification of mine ventilation, operator positioning and other work practices to reduce miners＇ exposures without waiting for laboratory analysis results.
文摘In a lab of the CAS Institute of Process Engineering（IPE）in Beijing,Winifred Uduak Anake,a visiting woman scientist from Covenant University.Nigeria was dashing to finish testing the 100 plus samples she collected from her home country.＂1 am trying to find out the type and amount of hazardous trace metals bound to the tiny particles trapped on the filters,＂she explained：＂out of worries about their possible threat to human health.＂Before concluding her three-month stay she needed to complete examining the morphology of the particles,total trace metals,
文摘Particulate emission is a major problem in industrial processes, mainly power plants that make use of coal as a primary source of energy. Stringent emissions limits, set by government organisations requires industries to conform to these limits to ensure that air quality is sustained and with minimum pollutant present. Electrostatic precipitators are typically used to filter and collect these particulate emissions. Fly ash resistivity is a primary parameter in the collection of particulate emissions, and there is a resistivity range at which electrostatic precipitator collection is most efficient and anything outside this range limits, their operation. High resistivity ash results in back-corona discharge, whilst low resistivity results in particle re-entrainment into the flue gas stream. The purpose of this paper is to investigate and obtain a fly ash resistivity profile for existing power plants in South Africa. Ash samples obtained from power plants are, tested making use of an ash-resistivity test oven, in accordance with IEEE Standard 548-1984. This paper discusses obtained experimental results, to determine the resistivity profile at which South African power plant electrostatic precipitators operate. The electrical efficiency of the electrostatic precipitator system is evaluated based on the obtained resistivity profiles.
