In this study, a temperature-based current sharing strategy rather than equal sharing for loads was applied to promote the reliability of uninterruptible power systems (UPS). According to the temperature of each power...In this study, a temperature-based current sharing strategy rather than equal sharing for loads was applied to promote the reliability of uninterruptible power systems (UPS). According to the temperature of each power supply module in a UPS, it would be better to reduce the output current ratio for a hotter supply module in the UPS. In this design, we implemented our regulation circuits by the UMC 0.25-μm CMOS technology with an input range from 3 V to 4.2 V and the regulated output at 1.1 V. The rated output current was 100 mA for each phase. We also employed a current-mode error-correction circuit to improve the current sharing performance based on the averaged current of each phase at the same temperature. According to our simulation results, the current sharing error can be restricted within ± 5% for the supply modules at the same temperature in our system.展开更多
Background Accurate estimation of potential evapotranspiration(PET)is the key for studying land-air interaction hydrological processes.Several models are used to estimate the PET based on standardized meteorological d...Background Accurate estimation of potential evapotranspiration(PET)is the key for studying land-air interaction hydrological processes.Several models are used to estimate the PET based on standardized meteorological data.Although combination-based models have the highest level performance estimation of PET,they require more meteorological data and may therefore be difficult to apply in areas lacking meteorological observation data.Results The results showed significant differences in the spatial trends of PET calculated by different models in China,the Doorenbots–Pruitts model revealed the highest PET(1902.6 mm),and the Kuzmin model revealed the lowest PET(349.6 mm),with the largest difference being 5.5 times.The Romanenko and the Rohwer models were the recommended temperature-based and aerodynamic-based models.On the other hand,the Abtew model was more suitable for arid and semi-arid regions,while the Priestley–Taylor model was more suitable for humid regions.Combination-based models revealed ideal calculation accuracies,among which the Penman–Monteith model was the best option for PET calculation.Conclusions The accuracy range of Romanenko,Rohwer,Abten,Priestley Taylor,and Penman Monteith models improved in MPZ and TCZ is higher than that improved in TMZ and SMZ.This does not mean that the improved models have higher accuracy in MPZ and TCZ than in TMZ and SMZ.On the contrary,the original model performed poorly in MPZ and TCZ,so the improved accuracy was relatively large.The unimproved model was already more suitable in TMZ and SMZ,so the improved accuracy was relatively small.Therefore,regional calibration of the PET models can improve the accuracy and applicability of PET calculation,providing a reference for studying hydrological processes in different climatic zones.展开更多
文摘In this study, a temperature-based current sharing strategy rather than equal sharing for loads was applied to promote the reliability of uninterruptible power systems (UPS). According to the temperature of each power supply module in a UPS, it would be better to reduce the output current ratio for a hotter supply module in the UPS. In this design, we implemented our regulation circuits by the UMC 0.25-μm CMOS technology with an input range from 3 V to 4.2 V and the regulated output at 1.1 V. The rated output current was 100 mA for each phase. We also employed a current-mode error-correction circuit to improve the current sharing performance based on the averaged current of each phase at the same temperature. According to our simulation results, the current sharing error can be restricted within ± 5% for the supply modules at the same temperature in our system.
基金National Natural Science Foundation of China[U2243202],[42230714,41977149]
文摘Background Accurate estimation of potential evapotranspiration(PET)is the key for studying land-air interaction hydrological processes.Several models are used to estimate the PET based on standardized meteorological data.Although combination-based models have the highest level performance estimation of PET,they require more meteorological data and may therefore be difficult to apply in areas lacking meteorological observation data.Results The results showed significant differences in the spatial trends of PET calculated by different models in China,the Doorenbots–Pruitts model revealed the highest PET(1902.6 mm),and the Kuzmin model revealed the lowest PET(349.6 mm),with the largest difference being 5.5 times.The Romanenko and the Rohwer models were the recommended temperature-based and aerodynamic-based models.On the other hand,the Abtew model was more suitable for arid and semi-arid regions,while the Priestley–Taylor model was more suitable for humid regions.Combination-based models revealed ideal calculation accuracies,among which the Penman–Monteith model was the best option for PET calculation.Conclusions The accuracy range of Romanenko,Rohwer,Abten,Priestley Taylor,and Penman Monteith models improved in MPZ and TCZ is higher than that improved in TMZ and SMZ.This does not mean that the improved models have higher accuracy in MPZ and TCZ than in TMZ and SMZ.On the contrary,the original model performed poorly in MPZ and TCZ,so the improved accuracy was relatively large.The unimproved model was already more suitable in TMZ and SMZ,so the improved accuracy was relatively small.Therefore,regional calibration of the PET models can improve the accuracy and applicability of PET calculation,providing a reference for studying hydrological processes in different climatic zones.
