Pearl millet at various moisture content （6.2, 9.4 and 12.3%, d.b.） and feed rates （3, 6 and 9 kg/h） was ground using hammer mill and its physical properties viz. arithmetic mean diameter, geometric mean diameter,...Pearl millet at various moisture content （6.2, 9.4 and 12.3%, d.b.） and feed rates （3, 6 and 9 kg/h） was ground using hammer mill and its physical properties viz. arithmetic mean diameter, geometric mean diameter, thousand grain weight, aspect ratio, specific surface area, surface area and bulk density were studied. Sieve analysis results showed that the increase in moisture content produced more medium sized particles with decreased percent weight retained in pan. Bond＇s work index, Kick＇s constant and average particle size were increased with the decrease in total surface area at higher moisture levels. The highest energy （2.34 KWh/kg） was consumed for 12.3% moisture content. Various grinding characteristics were significantly affected by moisture content and feed rate either individually or in combination and correlated in terms of Bond＇s work index, Kick＇s constant, total surface area, average particle size, effectiveness of milling and bulk density. Milling loss was found to be higher at lower moisture level and decreased with the increase of moisture content as well as feed rate. The loose and compact bulk density was ranged between 46.8-199.5 kg m^-3and 53.5-254.1 kg m^-3, respectively among the entire sieve fractions. Water absorption capacity increased with the decrease in particle size,展开更多
Spectral relative dispersion of different hydrometeors is vital to accurately describe sedimentation.Here,the Weather Research and Forecasting model with spectral bin microphysics is used to simulate convective clouds...Spectral relative dispersion of different hydrometeors is vital to accurately describe sedimentation.Here,the Weather Research and Forecasting model with spectral bin microphysics is used to simulate convective clouds in Shouxian of Anhui province in China to study the spectral relative dispersion of different hydrometeors.Firstly,regardless of clean or polluted conditions,the relative dispersion of ice crystal spectra and its volume-mean diameter are negatively correlated,while the relative dispersion of other hydrometeor spectra is positively related to their respective volume-mean diameter.The correlations for cloud droplets and raindrops are affected by the process of collision-coalescence;the correlations for ice crystals,graupel particles,and snow particles could be affected by the deposition,riming,and aggregation processes,respectively.Secondly,relative dispersion parameterizations are developed based on a comprehensive consideration of the relationships between the relative dispersion and volume-mean diameter under both polluted and clean conditions.Finally,the relative dispersion parameterizations are applied to terminal velocity parameterizations.The results show that for cloud droplets,ice crystals,graupel particles,and snow particles,assuming the shape parameter in the Gamma distribution is equal to 0 underestimates the shape parameter and overestimates the relative dispersion;and for raindrops,assuming the shape parameter is equal to 0 is close to the relative dispersion parameterizations.The most appropriate constant shape parameters are recommended for different hydrometeors.The relative dispersion parameterizations developed here shed new light for further optimizing the terminal velocity parameterizations in models.展开更多
文摘Pearl millet at various moisture content （6.2, 9.4 and 12.3%, d.b.） and feed rates （3, 6 and 9 kg/h） was ground using hammer mill and its physical properties viz. arithmetic mean diameter, geometric mean diameter, thousand grain weight, aspect ratio, specific surface area, surface area and bulk density were studied. Sieve analysis results showed that the increase in moisture content produced more medium sized particles with decreased percent weight retained in pan. Bond＇s work index, Kick＇s constant and average particle size were increased with the decrease in total surface area at higher moisture levels. The highest energy （2.34 KWh/kg） was consumed for 12.3% moisture content. Various grinding characteristics were significantly affected by moisture content and feed rate either individually or in combination and correlated in terms of Bond＇s work index, Kick＇s constant, total surface area, average particle size, effectiveness of milling and bulk density. Milling loss was found to be higher at lower moisture level and decreased with the increase of moisture content as well as feed rate. The loose and compact bulk density was ranged between 46.8-199.5 kg m^-3and 53.5-254.1 kg m^-3, respectively among the entire sieve fractions. Water absorption capacity increased with the decrease in particle size,
基金supported by the National Natural Science Foundation of China[Grant Nos.41822504,41775131,42027804,42075073,41975181,and 41775136].
文摘Spectral relative dispersion of different hydrometeors is vital to accurately describe sedimentation.Here,the Weather Research and Forecasting model with spectral bin microphysics is used to simulate convective clouds in Shouxian of Anhui province in China to study the spectral relative dispersion of different hydrometeors.Firstly,regardless of clean or polluted conditions,the relative dispersion of ice crystal spectra and its volume-mean diameter are negatively correlated,while the relative dispersion of other hydrometeor spectra is positively related to their respective volume-mean diameter.The correlations for cloud droplets and raindrops are affected by the process of collision-coalescence;the correlations for ice crystals,graupel particles,and snow particles could be affected by the deposition,riming,and aggregation processes,respectively.Secondly,relative dispersion parameterizations are developed based on a comprehensive consideration of the relationships between the relative dispersion and volume-mean diameter under both polluted and clean conditions.Finally,the relative dispersion parameterizations are applied to terminal velocity parameterizations.The results show that for cloud droplets,ice crystals,graupel particles,and snow particles,assuming the shape parameter in the Gamma distribution is equal to 0 underestimates the shape parameter and overestimates the relative dispersion;and for raindrops,assuming the shape parameter is equal to 0 is close to the relative dispersion parameterizations.The most appropriate constant shape parameters are recommended for different hydrometeors.The relative dispersion parameterizations developed here shed new light for further optimizing the terminal velocity parameterizations in models.
