A set of equations is suggested to describe the kinetics of degradation of organic compounds applied tosoils and the kinetics of growth of the involved microorganisme:where x is the concentration of organic compound a...A set of equations is suggested to describe the kinetics of degradation of organic compounds applied tosoils and the kinetics of growth of the involved microorganisme:where x is the concentration of organic compound at time t, m is the number of forcroorganisms capableof degrading the organic compound at time t, while j, k, f and g are positive constaats. This model cansatisfactorily be used to explain the degradation curve of organic compounds and the growth curve of theinvolved microorganisms.展开更多
Heavy metals are well recognized as potential health hazards as they can neither be degraded nor biologically detoxified. This experimental study aims to investigate the possible use of Libyan local soil, Ashkida soil...Heavy metals are well recognized as potential health hazards as they can neither be degraded nor biologically detoxified. This experimental study aims to investigate the possible use of Libyan local soil, Ashkida soil, mined in the Southern Province of Libya as a low cost adsorbent to remove copper ions from aqueous solutions. In this work, the effects of various parameters such as adsorbent dosage, initial concentration of copper, agitation rate, contact time and solution pH level on the adsorption efficiency are investigated through batch experiments at room temperature. The results indicate that the optimum conditions for copper removal from aqueous solutions are 60 minutes contact time, 10 g/L adsorbent dose and 500 rpm agitation rate at natural pH value. The results are fitted to Freundlich, Langmuir, Temkin and Dubinin-Radushkevich isotherms. A satisfactory agreement between the experimental data and the model-predicted values is expressed by the correlation coefficient, r^2, and the total mean error, E%. Freundlich model offers the best representation of adsorption process revealing a monolayer adsorption capacity, qmax, of 27.03 mg/g. A comparison of kinetic models applied to the adsorption of copper ions on the adsorbent is evaluated by simple first order, pseudo first order and pseudo second order kinetic models. Kinetic parameters, rate constant, equilibrium sorption capacities and related correlation coefficients for each kinetic model are determined revealing that the pseudo second order kinetic model is in a better correlation with the experimental data in comparison with the other isotherms.展开更多
This paper deduces a kinetic model for microbial degradation of pesticides in soils:where x is the concentration of pesticide at time t, so the initial concentration of the pesticide, me the initial number of pesticid...This paper deduces a kinetic model for microbial degradation of pesticides in soils:where x is the concentration of pesticide at time t, so the initial concentration of the pesticide, me the initial number of pesticide-degrading microorganisms, M the carrying capacity for the microorganisms, μ the specific growth rate of the microorganisms, and k the rate constant for the pesticide degradation.In periodic applications of pesticides, this model can be used to continuously describe every degradation curve. Whether a lag phase occurs or not, we can obtain the minimum residue of the pesticide (xe):xe=xdexp(-kMr)/[1-exp(-ker) ]where r is the regular time internals between applications, and xd the dosage of the pesticide.展开更多
In order to evaluate the impact of off-road terrains on the ride comfort of construction vehicles,a nonlinear dynamic model of the construction vehicles interacting with the terrain deformations is established based o...In order to evaluate the impact of off-road terrains on the ride comfort of construction vehicles,a nonlinear dynamic model of the construction vehicles interacting with the terrain deformations is established based on Matlab/Simulink software.The weighted root mean square(RMS)acceleration responses and the power spectral density(PSD)acceleration responses of the driver s seat heave,the pitch and roll angle of the cab in the low-frequency region are chosen as objective functions under different operation conditions of the vehicle.The results show that the impact of off-road terrains on the driver s ride comfort and health is clear under various conditions of deformable terrains and range of vehicle velocities.In particular,the driver s ride comfort is greatly affected by a soil terrain while the comfortable shake of the driver is strongly affected by a sand terrain.In addition,when the vehicle travels on a poor soil terrain in the frequency range below 4 Hz,more resonance peaks of acceleration PSD responses occurred than that on a rigid road of ISO 2631-1 level C.Thus,the driver s health is significantly affected by the deformable terrain in a low-frequency range.展开更多
Studies on Vertisols of Southwest China show that the distribution of organic matter, mechanicalcomposition, carbonates and spore-pollen in their profiles exhibits a definite differentiation and the radiocarbon age ha...Studies on Vertisols of Southwest China show that the distribution of organic matter, mechanicalcomposition, carbonates and spore-pollen in their profiles exhibits a definite differentiation and the radiocarbon age has a functional variation with soil depth, which suggests that pedoturbation model is a kind of incomplete model for genetic study and that the disturbance and inversion of solums of Vertisol are not as rapid and absolute as expected. In further consideration of the characters of swelling pressure and shear strength of Vertisol, vertic soil and other zonal soils, it is speculated that soil mechanics model is more adaptable for interpreting the morphogenesis of Vertisols without any contradiction with soil properties.展开更多
Soil frost heaving is a complex physical, mechanical, and chemical synthesis process. This paper summarizes the frost-heaving theory over half a century, including the capillary theory, the frozen-fringe theory, and t...Soil frost heaving is a complex physical, mechanical, and chemical synthesis process. This paper summarizes the frost-heaving theory over half a century, including the capillary theory, the frozen-fringe theory, and those achievements recently made by scholars. In this paper, we also discus researching achievements of the soil-prediction model during the past 40 years, including the water-dynamics model, the rigid-ice model, the segregation-potential model, and the thermo-dynamic model. This summary and discussion will enable readers to understand the latest direction of research; it also summarizes the development of frost-heave prediction models and their advantages and shortcomings.展开更多
Metolachlor retention on a Sharkey clay soil was quantified using a kinetic batch method for different initial solution concentrations. Time-dependent adsorption was carried out by monitoring solution concentration at...Metolachlor retention on a Sharkey clay soil was quantified using a kinetic batch method for different initial solution concentrations. Time-dependent adsorption was carried out by monitoring solution concentration at different reaction times. Adsorption was found to be highly kinetic in nature. Attempts were made to describe metolachlor retention based on a kinetic multireaction model which includes reversible and irreversible retention processes of the equilibrium and kinetic types. The predictive capability of the model for the description of experimental results for metolachlor retention was examined and proved to be adequate.展开更多
文摘A set of equations is suggested to describe the kinetics of degradation of organic compounds applied tosoils and the kinetics of growth of the involved microorganisme:where x is the concentration of organic compound at time t, m is the number of forcroorganisms capableof degrading the organic compound at time t, while j, k, f and g are positive constaats. This model cansatisfactorily be used to explain the degradation curve of organic compounds and the growth curve of theinvolved microorganisms.
文摘Heavy metals are well recognized as potential health hazards as they can neither be degraded nor biologically detoxified. This experimental study aims to investigate the possible use of Libyan local soil, Ashkida soil, mined in the Southern Province of Libya as a low cost adsorbent to remove copper ions from aqueous solutions. In this work, the effects of various parameters such as adsorbent dosage, initial concentration of copper, agitation rate, contact time and solution pH level on the adsorption efficiency are investigated through batch experiments at room temperature. The results indicate that the optimum conditions for copper removal from aqueous solutions are 60 minutes contact time, 10 g/L adsorbent dose and 500 rpm agitation rate at natural pH value. The results are fitted to Freundlich, Langmuir, Temkin and Dubinin-Radushkevich isotherms. A satisfactory agreement between the experimental data and the model-predicted values is expressed by the correlation coefficient, r^2, and the total mean error, E%. Freundlich model offers the best representation of adsorption process revealing a monolayer adsorption capacity, qmax, of 27.03 mg/g. A comparison of kinetic models applied to the adsorption of copper ions on the adsorbent is evaluated by simple first order, pseudo first order and pseudo second order kinetic models. Kinetic parameters, rate constant, equilibrium sorption capacities and related correlation coefficients for each kinetic model are determined revealing that the pseudo second order kinetic model is in a better correlation with the experimental data in comparison with the other isotherms.
文摘This paper deduces a kinetic model for microbial degradation of pesticides in soils:where x is the concentration of pesticide at time t, so the initial concentration of the pesticide, me the initial number of pesticide-degrading microorganisms, M the carrying capacity for the microorganisms, μ the specific growth rate of the microorganisms, and k the rate constant for the pesticide degradation.In periodic applications of pesticides, this model can be used to continuously describe every degradation curve. Whether a lag phase occurs or not, we can obtain the minimum residue of the pesticide (xe):xe=xdexp(-kMr)/[1-exp(-ker) ]where r is the regular time internals between applications, and xd the dosage of the pesticide.
基金The Science and Technology Support Program of Jiangsu Province(No.BE2014133)the Prospective Joint Research Program of Jiangsu Province(No.BY2014127-01)
文摘In order to evaluate the impact of off-road terrains on the ride comfort of construction vehicles,a nonlinear dynamic model of the construction vehicles interacting with the terrain deformations is established based on Matlab/Simulink software.The weighted root mean square(RMS)acceleration responses and the power spectral density(PSD)acceleration responses of the driver s seat heave,the pitch and roll angle of the cab in the low-frequency region are chosen as objective functions under different operation conditions of the vehicle.The results show that the impact of off-road terrains on the driver s ride comfort and health is clear under various conditions of deformable terrains and range of vehicle velocities.In particular,the driver s ride comfort is greatly affected by a soil terrain while the comfortable shake of the driver is strongly affected by a sand terrain.In addition,when the vehicle travels on a poor soil terrain in the frequency range below 4 Hz,more resonance peaks of acceleration PSD responses occurred than that on a rigid road of ISO 2631-1 level C.Thus,the driver s health is significantly affected by the deformable terrain in a low-frequency range.
文摘Studies on Vertisols of Southwest China show that the distribution of organic matter, mechanicalcomposition, carbonates and spore-pollen in their profiles exhibits a definite differentiation and the radiocarbon age has a functional variation with soil depth, which suggests that pedoturbation model is a kind of incomplete model for genetic study and that the disturbance and inversion of solums of Vertisol are not as rapid and absolute as expected. In further consideration of the characters of swelling pressure and shear strength of Vertisol, vertic soil and other zonal soils, it is speculated that soil mechanics model is more adaptable for interpreting the morphogenesis of Vertisols without any contradiction with soil properties.
文摘Soil frost heaving is a complex physical, mechanical, and chemical synthesis process. This paper summarizes the frost-heaving theory over half a century, including the capillary theory, the frozen-fringe theory, and those achievements recently made by scholars. In this paper, we also discus researching achievements of the soil-prediction model during the past 40 years, including the water-dynamics model, the rigid-ice model, the segregation-potential model, and the thermo-dynamic model. This summary and discussion will enable readers to understand the latest direction of research; it also summarizes the development of frost-heave prediction models and their advantages and shortcomings.
文摘Metolachlor retention on a Sharkey clay soil was quantified using a kinetic batch method for different initial solution concentrations. Time-dependent adsorption was carried out by monitoring solution concentration at different reaction times. Adsorption was found to be highly kinetic in nature. Attempts were made to describe metolachlor retention based on a kinetic multireaction model which includes reversible and irreversible retention processes of the equilibrium and kinetic types. The predictive capability of the model for the description of experimental results for metolachlor retention was examined and proved to be adequate.
