This study employed numerical simulations to explore the impact of varying ice nucleation processes on the microphysics and electrification within thunderstorm clouds.A two-dimensional cumulus model,incorporating both...This study employed numerical simulations to explore the impact of varying ice nucleation processes on the microphysics and electrification within thunderstorm clouds.A two-dimensional cumulus model,incorporating both noninductive and inductive charge separation schemes,was utilized.The findings revealed that the freezing nucleation mechanism significantly influenced the microphysical development,electrification,and charge structure of thunderstorms.Homogeneous freezing generated a large quantity of small ice crystals near the cloud tops,which were primarily responsible for the development of positive charge regions through a non-inductive charging process.Conversely,heterogeneous freezing resulted in larger ice crystals,enhancing graupel formation and leading to a more rapid and intense charge separation rate of around-15°C.Ice crystals formed heterogeneously and charged negatively during the development stage,resulting in an inverted dipole charge structure.When both immersion and homogeneous freezing processes were considered,the competition between these two distinct freezing processes resulted in reduced cloud water content and weaker electrification.Under conditions of low cloud water content at lower storm levels,graupel particles were negatively charged through non-inductive charging,causing the charge structure to quickly revert to a normal dipole structure.展开更多
为研究不同功率超声辅助浸渍冷冻对牛肉品质的影响,选取传统风冷和0、200、400、600 W 4组不同功率超声波辅助冷冻处理牛肉,以鲜肉组为对照,分析其冻结速率、蒸煮损失、解冻损失、嫩度、色差值、水分分布和微观结构等变化情况。结果表明...为研究不同功率超声辅助浸渍冷冻对牛肉品质的影响,选取传统风冷和0、200、400、600 W 4组不同功率超声波辅助冷冻处理牛肉,以鲜肉组为对照,分析其冻结速率、蒸煮损失、解冻损失、嫩度、色差值、水分分布和微观结构等变化情况。结果表明:超声波辅助可以提升牛肉的冻结速率,影响牛肉色泽和水分状态,减轻冷冻过程中肌肉组织结构破坏和品质劣变。当超声波功率为400 W时,牛肉冻结速率最快,且蒸煮损失和解冻损失最低,分别为32.44%和1.66%,剪切力与鲜肉组也最为接近;另外,功率400 W时冷冻牛肉可冻结水质量分数最小,为51.11%;低场核磁分析表明,T21振幅最大,T22振幅变化较小,水分分布也更加均匀;微观结构观察显示,适当的功率超声辅助处理下,能减少冷冻过程对肌纤维及组织网络结构的破坏,从而改善冷冻肉的品质。展开更多
Objectives:Optimization of ultrasonic-assisted freezing of Penaeus chinensis by response surface methodology was studied in order to(1)obtain frozen Penaeus chinensis of high quality and(2)provide practical guidance f...Objectives:Optimization of ultrasonic-assisted freezing of Penaeus chinensis by response surface methodology was studied in order to(1)obtain frozen Penaeus chinensis of high quality and(2)provide practical guidance for the application of ultrasonic-assisted freezing in Penaeus chinensis.Materials and Methods:Three independent and major variables were selected,including initial ultrasonic temperature(℃),ultrasonic power(W)and ultrasonic time(s on/2 s off).On the basis of one-factor experiments,17 groups of experiments were established by response surface methodology according to Box-Behnken design.Using multiple regression analysis the experimental data were fitted into a second-order polynomial equation,which was tested by proper statistical methods.Results:The optimal ultrasonic conditions were as follows:initial ultrasonic temperature 0℃,ultrasonic power 180 W,ultrasonic time 5 son/2 s off.Under the optimization conditions,the time of passing through maximum ice crystal generation zone was 105.500 s,which was very close to the predictive passage time of 101.541 s.Conclusions:Initial ultrasonic temperature,ultrasonic time and ultrasonic power played an important role in the process of ultrasonic-assisted freezing of Penaeus chinensis.Response surface methodology was used to optimize the three factors in ultrasonic-assisted freezing,which could greatly shorten the time of passing through the maximum ice crystal generation zone and maintain the tissue structure of Penaeus chinensis well.展开更多
基金National Natural Science Foundation of China (41805002)Joint Funds of the Zhejiang Provincial Natural Science Foundation of China (LZJMZ24D050009)+1 种基金Startup Foundation for Introducing Talent of NUIST (2016r042)Hubei Provincial Natural Science Foundation of China (2021CFB571)。
文摘This study employed numerical simulations to explore the impact of varying ice nucleation processes on the microphysics and electrification within thunderstorm clouds.A two-dimensional cumulus model,incorporating both noninductive and inductive charge separation schemes,was utilized.The findings revealed that the freezing nucleation mechanism significantly influenced the microphysical development,electrification,and charge structure of thunderstorms.Homogeneous freezing generated a large quantity of small ice crystals near the cloud tops,which were primarily responsible for the development of positive charge regions through a non-inductive charging process.Conversely,heterogeneous freezing resulted in larger ice crystals,enhancing graupel formation and leading to a more rapid and intense charge separation rate of around-15°C.Ice crystals formed heterogeneously and charged negatively during the development stage,resulting in an inverted dipole charge structure.When both immersion and homogeneous freezing processes were considered,the competition between these two distinct freezing processes resulted in reduced cloud water content and weaker electrification.Under conditions of low cloud water content at lower storm levels,graupel particles were negatively charged through non-inductive charging,causing the charge structure to quickly revert to a normal dipole structure.
文摘为研究不同功率超声辅助浸渍冷冻对牛肉品质的影响,选取传统风冷和0、200、400、600 W 4组不同功率超声波辅助冷冻处理牛肉,以鲜肉组为对照,分析其冻结速率、蒸煮损失、解冻损失、嫩度、色差值、水分分布和微观结构等变化情况。结果表明:超声波辅助可以提升牛肉的冻结速率,影响牛肉色泽和水分状态,减轻冷冻过程中肌肉组织结构破坏和品质劣变。当超声波功率为400 W时,牛肉冻结速率最快,且蒸煮损失和解冻损失最低,分别为32.44%和1.66%,剪切力与鲜肉组也最为接近;另外,功率400 W时冷冻牛肉可冻结水质量分数最小,为51.11%;低场核磁分析表明,T21振幅最大,T22振幅变化较小,水分分布也更加均匀;微观结构观察显示,适当的功率超声辅助处理下,能减少冷冻过程对肌纤维及组织网络结构的破坏,从而改善冷冻肉的品质。
基金the National Key Research and Development of China(No.2016YFD0400102)National Natural Science Foundation of China(No.31671918).
文摘Objectives:Optimization of ultrasonic-assisted freezing of Penaeus chinensis by response surface methodology was studied in order to(1)obtain frozen Penaeus chinensis of high quality and(2)provide practical guidance for the application of ultrasonic-assisted freezing in Penaeus chinensis.Materials and Methods:Three independent and major variables were selected,including initial ultrasonic temperature(℃),ultrasonic power(W)and ultrasonic time(s on/2 s off).On the basis of one-factor experiments,17 groups of experiments were established by response surface methodology according to Box-Behnken design.Using multiple regression analysis the experimental data were fitted into a second-order polynomial equation,which was tested by proper statistical methods.Results:The optimal ultrasonic conditions were as follows:initial ultrasonic temperature 0℃,ultrasonic power 180 W,ultrasonic time 5 son/2 s off.Under the optimization conditions,the time of passing through maximum ice crystal generation zone was 105.500 s,which was very close to the predictive passage time of 101.541 s.Conclusions:Initial ultrasonic temperature,ultrasonic time and ultrasonic power played an important role in the process of ultrasonic-assisted freezing of Penaeus chinensis.Response surface methodology was used to optimize the three factors in ultrasonic-assisted freezing,which could greatly shorten the time of passing through the maximum ice crystal generation zone and maintain the tissue structure of Penaeus chinensis well.
