With increasing awareness of myopia control,various preventive methods have been developed.In recent decades,a range of specialized spectacle lenses utilizing optical interventions has been manufactured and widely ado...With increasing awareness of myopia control,various preventive methods have been developed.In recent decades,a range of specialized spectacle lenses utilizing optical interventions has been manufactured and widely adopted for myopia management.However,the underlying optical mechanisms of these lenses remain unclear,and there is a lack of simulation methods for pre-manufacturing analysis.Meanwhile,the structures of these lenses are becoming increasingly complex,even incorporating an aspheric segment array on a curved base.To address these challenges,we have developed an efficient,accurate,and flexible modeling method for simulating such lenses,along with an experimental setup for validation.We provide deeper insights into the optical mechanisms of these lenses and establish a convenient design framework that facilitates the development of optimized lens structures.展开更多
The results from a hybrid approach that combines a mesoscale meteorological model with a diagnostic model to produce high-resolution wind fields in complex coastal topography are evaluated.The diagnostic wind model(Ca...The results from a hybrid approach that combines a mesoscale meteorological model with a diagnostic model to produce high-resolution wind fields in complex coastal topography are evaluated.The diagnostic wind model(California Meteorological Model,CALMET) with 100-m horizontal spacing was driven with outputs from the Weather Research and Forecasting(WRF) model to obtain near-surface winds for the 1-year period from 12 September 2003 to 11 September 2004.Results were compared with wind observations at four sites.Traditional statistical scores,including correlation coefficients,standard deviations(SDs) and mean absolute errors(MAEs),indicate that the wind estimates from the WRF/CALMET modeling system are produced reasonably well.The correlation coefficients are relatively large,ranging from 0.5 to 0.7 for the zonal wind component and from 0.75 to 0.85 for the meridional wind component.MAEs for wind speed range from 1.5 to 2.0 m s-1 at 10 meters above ground level(AGL) and from 2.0 to 2.5 m s-1 at 60 m AGL.MAEs for wind direction range from 30 to 40 degrees at both levels.A spectral decomposition of the time series of wind speed shows positive impacts of CALMET in improving the mesoscale winds.Moreover,combining the CALMET model with WRF significantly improves the spatial variability of the simulated wind fields.It can be concluded that the WRF/CALMET modeling system is capable of providing a detailed near-surface wind field,but the physics in the diagnostic CALMET model needs to be further improved.展开更多
The interaction between radionuclides and solid/water interfaces is important to understand the physicochemical processes of radionuclides in the natural environment.Herein,the interaction of 60Co(Ⅱ) with TiO 2 in aq...The interaction between radionuclides and solid/water interfaces is important to understand the physicochemical processes of radionuclides in the natural environment.Herein,the interaction of 60Co(Ⅱ) with TiO 2 in aqueous solution as a function of pH and ionic strength was studied by using batch technique combined with surface complexation model and density functional theory(DFT) calculations.The batch experimental results showed that the adsorption of 60Co(Ⅱ) was dependent on pH and independent of ionic strength,indicating the formation of inner-sphere surface complexes on TiO 2 surfaces.The results of surface complexation models and DFT calculations indicated that the surface species of 60Co(Ⅱ) adsorbed on TiO 2 followed the trend:B structure(i.e.,60Co(Ⅱ) was linked to one bridge oxygen site) was the dominant surface species at low pH,and TT structure(i.e.,60Co(Ⅱ) was linked to two terminal oxygen sites) became the important surface complex at neutral and alkaline pH values.These results demonstrated that a multi-technique approach could lead to definitive information on the structures of adsorbed 60Co(Ⅱ) at the molecular level at the TiO 2 /water interfaces,as well as realistic models to rationalize and accurately evaluate the macroscopic manifestations of radionuclide adsorption phenomena.展开更多
A mass-conservative average flow model based on the finite element method(FEM) is introduced to predict the performances of textured surfaces applied in mechanical seals or thrust bearings.In this model,the Jakobsson-...A mass-conservative average flow model based on the finite element method(FEM) is introduced to predict the performances of textured surfaces applied in mechanical seals or thrust bearings.In this model,the Jakobsson-Floberg-Olsson(JFO) boundary conditions are applied to the average flow model for ensuring the mass-conservative law.Moreover,the non-uniform triangular grid is utilized,which can deal with the problem of complex geometric shapes.By adopting the modeling techniques,the model proposed here is capable of dealing with complex textured surfaces.The algorithm is proved correct by the numerical experiment.In addition,the model is employed to gain further insight into the influences of the dimples with different shapes and orientations on smooth and rough surfaces on the load-carrying capacity.展开更多
A controlled hydroponic experiment was undertaken to investigate Cd uptake in relation to the activity of Cd species in solution other than the free ion （Cd^2＋） by maintaining a constant Cd^2＋ activity under varia...A controlled hydroponic experiment was undertaken to investigate Cd uptake in relation to the activity of Cd species in solution other than the free ion （Cd^2＋） by maintaining a constant Cd^2＋ activity under variable SO4^2- and Cl^- concentrations exposed to maize （Zea mays vat. Cameron） plants. The objectives of these experiments were： （1） to distinguish and quantify the different uptake rates of free and inorganic-complexed Cd from nutrient solution, and （2） to model the uptake of Cd by maize with a Biotic Ligand Model （BLM） in a system which facilitates the close examination of root characteristics. Results of the current experiments suggest that, in addition to the free ion, CdSO4^0 complexes are important factors in determining Cd uptake in nutrient solution by maize plants. Higher nominal SO4^2- concentrations in solution generally resulted in a greater Cd accumulation by maize plants than predicted by the Cd^2＋ activity. A better integration of the complete dataset for the 3 harvest times （6, 9 and 11 days after treatment） was achieved by including consideration of both the duration of Cd exposure and especially the root surface area to express Cd uptake. Similarly, the fit of the BLM was also improved when taking into account exposure time and expressing uptake in terms of root morphological parameters.展开更多
In this study,the surface properties and adsorption properties of the Le An River sedi- ment were modelled via surface complexation approach.The model parameters were determined based on the data of our potentiometric...In this study,the surface properties and adsorption properties of the Le An River sedi- ment were modelled via surface complexation approach.The model parameters were determined based on the data of our potentiometric titration experiments and the metal adsorption experiments with the Le An River sediment samples.Consequently,the surface complexation models for the natural sediment,in our case the Le An River sediments,which can interpret the experimental data very well were successfully established.Three typical surface complexation models that is the con- stant capacitance model,the diffuse layer model and the triple layer model,were considered in this research.This work indicated that the consistency and the interdependency among model parame- ters together with the selection of the surface adsorbed species should be emphasized.展开更多
This study investigated the performance of the mesoscale Weather Research and Forecasting(WRF) model in predicting near-surface atmospheric temperature and wind for a complex underlying surface in Northwest China in J...This study investigated the performance of the mesoscale Weather Research and Forecasting(WRF) model in predicting near-surface atmospheric temperature and wind for a complex underlying surface in Northwest China in June and December 2015. The spatial distribution of the monthly average bias errors in the forecasts of 2-m temperature and 10-m wind speed is analyzed first. It is found that the forecast errors for 2-m temperature and 10-m wind speed in June are strongly correlated with the terrain distribution. However, this type of correlation is not apparent in December, perhaps due to the inaccurate specification of the surface albedo and freezing-thawing process of frozen soil in winter in Northwest China in the WRF model. In addition, the WRF model is able to reproduce the diurnal variation in 2-m temperature and 10-m wind speed, although with weakened magnitude. Elevations and land-use types have strong influences on the forecast of near-surface variables with seasonal variations. The overall results imply that accurate specification of the complex underlying surface and seasonal changes in land cover is necessary for improving near-surface forecasts over Northwest China.展开更多
This study investigates the potential of natural Brown Coal(BC)as a sustainable,cost-effective adsorbent for the removal of manganese(Mn2+)from contaminated groundwater.A series of batch adsorp-tion experiments was co...This study investigates the potential of natural Brown Coal(BC)as a sustainable,cost-effective adsorbent for the removal of manganese(Mn2+)from contaminated groundwater.A series of batch adsorp-tion experiments was conducted to assess the influence of key operational parameters—such as solution pH,2+initial Mn concentration,BC dosage,temperature,and the presence of competing ions—on 2+Mn removal efficiency.The environmental compatibility and regeneration potential of BC were also evaluated to deter-mine its practical viability for repeated use.To better understand the adsorption behaviour,equilibrium and kinetic data were analysed using established isotherm and kinetic models,while thermodynamic parameters were computed to assess the spontaneity and thermal characteristics of the adsorption process.Furthermore,geochemical modelling and comprehensive BC characterization—including surface morphology,miner-alogical and elemental composition,and functional group analysis—were 2+performed to elucidate Mn speciation under varying environmental conditions and to uncover the underlying adsorption mechanisms.2+Results showed that Mn removal efficiency increased with higher pH,temperature,and BC dosage,but 2+declined at elevated initial Mn concentrations due to active site saturation.The process was spontaneous 2 and endothermic,with the Langmuir isotherm model(R=0.994)and pseudo-second-order kinetic model 2(R=0.996)providing the best fit to experimental data.Mechanistic analysis indicated that chemisorption,2+primarily through ion exchange and inner-sphere complexation,was the dominant mode of Mn uptake.3+The presence of competing cations,especially Fe and Cu2+,2+significantly hindered Mn removal due to preferential binding.Importantly,BC exhibited strong reusability,maintaining over 80%removal effi-ciency across four adsorption–desorption cycles without evidence of secondary pollutants.These findings demonstrate the potential of natural BC as an efficient,reusable,and environmentally benign material for treating manganese-contaminated groundwater.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.62475015)。
文摘With increasing awareness of myopia control,various preventive methods have been developed.In recent decades,a range of specialized spectacle lenses utilizing optical interventions has been manufactured and widely adopted for myopia management.However,the underlying optical mechanisms of these lenses remain unclear,and there is a lack of simulation methods for pre-manufacturing analysis.Meanwhile,the structures of these lenses are becoming increasingly complex,even incorporating an aspheric segment array on a curved base.To address these challenges,we have developed an efficient,accurate,and flexible modeling method for simulating such lenses,along with an experimental setup for validation.We provide deeper insights into the optical mechanisms of these lenses and establish a convenient design framework that facilitates the development of optimized lens structures.
基金National Public Benefit Research Foundation of China (2008416048GYHY201006035)
文摘The results from a hybrid approach that combines a mesoscale meteorological model with a diagnostic model to produce high-resolution wind fields in complex coastal topography are evaluated.The diagnostic wind model(California Meteorological Model,CALMET) with 100-m horizontal spacing was driven with outputs from the Weather Research and Forecasting(WRF) model to obtain near-surface winds for the 1-year period from 12 September 2003 to 11 September 2004.Results were compared with wind observations at four sites.Traditional statistical scores,including correlation coefficients,standard deviations(SDs) and mean absolute errors(MAEs),indicate that the wind estimates from the WRF/CALMET modeling system are produced reasonably well.The correlation coefficients are relatively large,ranging from 0.5 to 0.7 for the zonal wind component and from 0.75 to 0.85 for the meridional wind component.MAEs for wind speed range from 1.5 to 2.0 m s-1 at 10 meters above ground level(AGL) and from 2.0 to 2.5 m s-1 at 60 m AGL.MAEs for wind direction range from 30 to 40 degrees at both levels.A spectral decomposition of the time series of wind speed shows positive impacts of CALMET in improving the mesoscale winds.Moreover,combining the CALMET model with WRF significantly improves the spatial variability of the simulated wind fields.It can be concluded that the WRF/CALMET modeling system is capable of providing a detailed near-surface wind field,but the physics in the diagnostic CALMET model needs to be further improved.
基金Progress of Projects Supported by NSFCsupported by the National Basic Research Program of China (2011CB933700)the National Natural Science Foundation of China (20907055,20971126,21071147,91126020,21077107)
文摘The interaction between radionuclides and solid/water interfaces is important to understand the physicochemical processes of radionuclides in the natural environment.Herein,the interaction of 60Co(Ⅱ) with TiO 2 in aqueous solution as a function of pH and ionic strength was studied by using batch technique combined with surface complexation model and density functional theory(DFT) calculations.The batch experimental results showed that the adsorption of 60Co(Ⅱ) was dependent on pH and independent of ionic strength,indicating the formation of inner-sphere surface complexes on TiO 2 surfaces.The results of surface complexation models and DFT calculations indicated that the surface species of 60Co(Ⅱ) adsorbed on TiO 2 followed the trend:B structure(i.e.,60Co(Ⅱ) was linked to one bridge oxygen site) was the dominant surface species at low pH,and TT structure(i.e.,60Co(Ⅱ) was linked to two terminal oxygen sites) became the important surface complex at neutral and alkaline pH values.These results demonstrated that a multi-technique approach could lead to definitive information on the structures of adsorbed 60Co(Ⅱ) at the molecular level at the TiO 2 /water interfaces,as well as realistic models to rationalize and accurately evaluate the macroscopic manifestations of radionuclide adsorption phenomena.
基金supported by the National Basic Research Program of China(Grant No.2009CB724304)the National Key Technology R&D Program(Grant No.2011BAF09B05)+1 种基金the National Natural Science Foundation of China(Grant No.50975157)the Key Research Program of the State Key Laboratory of Tribology of Tsinghua University(Grant No.SKLT08A06)
文摘A mass-conservative average flow model based on the finite element method(FEM) is introduced to predict the performances of textured surfaces applied in mechanical seals or thrust bearings.In this model,the Jakobsson-Floberg-Olsson(JFO) boundary conditions are applied to the average flow model for ensuring the mass-conservative law.Moreover,the non-uniform triangular grid is utilized,which can deal with the problem of complex geometric shapes.By adopting the modeling techniques,the model proposed here is capable of dealing with complex textured surfaces.The algorithm is proved correct by the numerical experiment.In addition,the model is employed to gain further insight into the influences of the dimples with different shapes and orientations on smooth and rough surfaces on the load-carrying capacity.
基金supported by the Severn Trent Water Ltd. as co-funders of the Biorem 11 (PASS) Project under the Bioremediation Link Programme (UK BBSRC)the financia support from CONACYT,Mexico (No. 137972)
文摘A controlled hydroponic experiment was undertaken to investigate Cd uptake in relation to the activity of Cd species in solution other than the free ion （Cd^2＋） by maintaining a constant Cd^2＋ activity under variable SO4^2- and Cl^- concentrations exposed to maize （Zea mays vat. Cameron） plants. The objectives of these experiments were： （1） to distinguish and quantify the different uptake rates of free and inorganic-complexed Cd from nutrient solution, and （2） to model the uptake of Cd by maize with a Biotic Ligand Model （BLM） in a system which facilitates the close examination of root characteristics. Results of the current experiments suggest that, in addition to the free ion, CdSO4^0 complexes are important factors in determining Cd uptake in nutrient solution by maize plants. Higher nominal SO4^2- concentrations in solution generally resulted in a greater Cd accumulation by maize plants than predicted by the Cd^2＋ activity. A better integration of the complete dataset for the 3 harvest times （6, 9 and 11 days after treatment） was achieved by including consideration of both the duration of Cd exposure and especially the root surface area to express Cd uptake. Similarly, the fit of the BLM was also improved when taking into account exposure time and expressing uptake in terms of root morphological parameters.
基金This work was supported by the National Natural Science Foundation of China.
文摘In this study,the surface properties and adsorption properties of the Le An River sedi- ment were modelled via surface complexation approach.The model parameters were determined based on the data of our potentiometric titration experiments and the metal adsorption experiments with the Le An River sediment samples.Consequently,the surface complexation models for the natural sediment,in our case the Le An River sediments,which can interpret the experimental data very well were successfully established.Three typical surface complexation models that is the con- stant capacitance model,the diffuse layer model and the triple layer model,were considered in this research.This work indicated that the consistency and the interdependency among model parame- ters together with the selection of the surface adsorbed species should be emphasized.
基金Supported by the China Meteorological Administration Special Public Welfare Research Fund(GYHY201506001)Northwest Regional Numerical Forecasting Innovation Team Fund(GSQXCXTD-2017-02)
文摘This study investigated the performance of the mesoscale Weather Research and Forecasting(WRF) model in predicting near-surface atmospheric temperature and wind for a complex underlying surface in Northwest China in June and December 2015. The spatial distribution of the monthly average bias errors in the forecasts of 2-m temperature and 10-m wind speed is analyzed first. It is found that the forecast errors for 2-m temperature and 10-m wind speed in June are strongly correlated with the terrain distribution. However, this type of correlation is not apparent in December, perhaps due to the inaccurate specification of the surface albedo and freezing-thawing process of frozen soil in winter in Northwest China in the WRF model. In addition, the WRF model is able to reproduce the diurnal variation in 2-m temperature and 10-m wind speed, although with weakened magnitude. Elevations and land-use types have strong influences on the forecast of near-surface variables with seasonal variations. The overall results imply that accurate specification of the complex underlying surface and seasonal changes in land cover is necessary for improving near-surface forecasts over Northwest China.
文摘This study investigates the potential of natural Brown Coal(BC)as a sustainable,cost-effective adsorbent for the removal of manganese(Mn2+)from contaminated groundwater.A series of batch adsorp-tion experiments was conducted to assess the influence of key operational parameters—such as solution pH,2+initial Mn concentration,BC dosage,temperature,and the presence of competing ions—on 2+Mn removal efficiency.The environmental compatibility and regeneration potential of BC were also evaluated to deter-mine its practical viability for repeated use.To better understand the adsorption behaviour,equilibrium and kinetic data were analysed using established isotherm and kinetic models,while thermodynamic parameters were computed to assess the spontaneity and thermal characteristics of the adsorption process.Furthermore,geochemical modelling and comprehensive BC characterization—including surface morphology,miner-alogical and elemental composition,and functional group analysis—were 2+performed to elucidate Mn speciation under varying environmental conditions and to uncover the underlying adsorption mechanisms.2+Results showed that Mn removal efficiency increased with higher pH,temperature,and BC dosage,but 2+declined at elevated initial Mn concentrations due to active site saturation.The process was spontaneous 2 and endothermic,with the Langmuir isotherm model(R=0.994)and pseudo-second-order kinetic model 2(R=0.996)providing the best fit to experimental data.Mechanistic analysis indicated that chemisorption,2+primarily through ion exchange and inner-sphere complexation,was the dominant mode of Mn uptake.3+The presence of competing cations,especially Fe and Cu2+,2+significantly hindered Mn removal due to preferential binding.Importantly,BC exhibited strong reusability,maintaining over 80%removal effi-ciency across four adsorption–desorption cycles without evidence of secondary pollutants.These findings demonstrate the potential of natural BC as an efficient,reusable,and environmentally benign material for treating manganese-contaminated groundwater.
