For development of passenger electrical transport, it is necessary to use energy more rationally. One of methods of vehicle power efficiency increase is installation of on-board energy storage systems. For studying of...For development of passenger electrical transport, it is necessary to use energy more rationally. One of methods of vehicle power efficiency increase is installation of on-board energy storage systems. For studying of system operation, it is necessary to carry out a lot of experiments, therefore it is favorable to use the test bench and its computer model for reduction of the number of physical experiments. In this article, the results of computer modeling for the optimization of traction drive test bench by adjusting of the operation parameters of supercapacitor energy storage are described. Test bench operation is considered in cases of the energy storage system working at various selected supercapacitor initial voltages. Maximal increase of possibility of vehicle test bench regenerative braking with minimal decrease of autonomous power supply mode possibility is investigated. There is estimated the energy storage system efficiency improving measures dependence from supercapacitor operational voltage ranges. Parameters at which the minimum losses of energy are observed are revealed. Dependence of energy storage system discharge power on the most admissible supercapacitor current is established.展开更多
The spatio-temporal pattern of the global water resource has significantly changed with climate change and intensified human activities. The regional economy and ecological environment are highly affected by terrestri...The spatio-temporal pattern of the global water resource has significantly changed with climate change and intensified human activities. The regional economy and ecological environment are highly affected by terrestrial water storage(TWS), especially in arid areas. To investigate the response relationships between TWS and changing environments(climate change and human activities) in Central Asia, we used the Gravity Recovery and Climate Experiment(GRACE) data, Climatic Research Unit(CRU) climate data and Moderate Resolution Imaging Spectroradiometer(MODIS) remote sensing data products(MOD16A2, MOD13A3 and MCD12Q1) from 2003 to 2013, as well as the slope and Pearson correlation analysis methods. Results indicate that:(1) TWS in about 77% of the study area decreased from 2003 to 2013. The total change volume of TWS is about 2915.6 × 108 m^3. The areas of decreased TWS are mainly distributed in the middle of Central Asia, while the areas of increased TWS are concentrated in the middle-altitude regions of the Kazakhstan hills and Tarim Basin.(2) TWS in about 5.91% of areas, mainly distributed in the mountain and piedmont zones, is significantly positively correlated with precipitation, while only 3.78% of areas show significant correlation between TWS and temperature. If the response time was delayed by three months, there would be a very good correlation between temperature and TWS.(3) There is a significantly positive relationship between TWS and Normalized Difference Vegetation Index(NDVI) in 13.35% of the study area.(4) The area of significantly positive correlation between TWS and evapotranspiration is about 31.87%, mainly situated in mountainous areas and northwestern Kazakhstan. The reduction of regional TWS is related to precipitation more than evaporation. Increasing farmland area may explain why some areas show increasing precipitation and decreasing evapotranspiration.(5) The influences of land use on TWS are still not very clear. This study could provide scientific data useful for the estimation of changes in TWS with climate change and human activities.展开更多
A fundamental understanding of the electrochemical reaction process and mechanism of electrodes is very crucial for developing high-performance electrode materials.In this study,we report the sodium ion storage behavi...A fundamental understanding of the electrochemical reaction process and mechanism of electrodes is very crucial for developing high-performance electrode materials.In this study,we report the sodium ion storage behavior and mechanism of orthorhombic V_(2)O_(5) single-crystalline nanowires in the voltage window of 1.0–4.0 V(vs.Na/Na+).The single-crystalline nanowires exhibit a large irreversible capacity loss during the first discharge/charge cycle,and then show excellent cycling stability in the following cycles.At a current density of 100 mA g^(−1),the nanowires electrode delivers initial discharge/charge capacity of 217/88 mA h g^(−1),corresponding to a Coulombic efficiency of only 40.5%;after 100 cycles,the electrode remains a reversible discharge capacity of 78 mA h g^(−1) with a fading rate of only 0.09%per cycle compared with the 2nd cycle discharge capacity.The sodium ion storage mechanism was investigated,illustrating that the large irreversible capacity loss in the first cycle can be attributed to the initially formed single-crystalline α′-Nax V_(2)O_(5)(0.02<x<0.88),in which sodium ions cannot be electrochemically extracted and the α′-Na0.88 V_(2)O_(5) can reversibly host and release sodium ions via a single-phase(solid solution)reaction,leading to excellent cycling stability.The Na^(+) diffusion coefficient in α′-Nax V_(2)O_(5) ranges from 10^(−12) to 10^(−11.5) cm^(2) s^(−1) as evaluated by galvanostatic intermittent titration technique(GITT).展开更多
文摘For development of passenger electrical transport, it is necessary to use energy more rationally. One of methods of vehicle power efficiency increase is installation of on-board energy storage systems. For studying of system operation, it is necessary to carry out a lot of experiments, therefore it is favorable to use the test bench and its computer model for reduction of the number of physical experiments. In this article, the results of computer modeling for the optimization of traction drive test bench by adjusting of the operation parameters of supercapacitor energy storage are described. Test bench operation is considered in cases of the energy storage system working at various selected supercapacitor initial voltages. Maximal increase of possibility of vehicle test bench regenerative braking with minimal decrease of autonomous power supply mode possibility is investigated. There is estimated the energy storage system efficiency improving measures dependence from supercapacitor operational voltage ranges. Parameters at which the minimum losses of energy are observed are revealed. Dependence of energy storage system discharge power on the most admissible supercapacitor current is established.
基金National Natural Science Foundation of China,No.51569027No.41371419+1 种基金International Partnership Program of the Chinese Academy of Sciences,No.131551KYSB20160002Special Institute Main Service Program of the Chinese Academy of Sciences,No.TSS-2015-014-FW-1-2
文摘The spatio-temporal pattern of the global water resource has significantly changed with climate change and intensified human activities. The regional economy and ecological environment are highly affected by terrestrial water storage(TWS), especially in arid areas. To investigate the response relationships between TWS and changing environments(climate change and human activities) in Central Asia, we used the Gravity Recovery and Climate Experiment(GRACE) data, Climatic Research Unit(CRU) climate data and Moderate Resolution Imaging Spectroradiometer(MODIS) remote sensing data products(MOD16A2, MOD13A3 and MCD12Q1) from 2003 to 2013, as well as the slope and Pearson correlation analysis methods. Results indicate that:(1) TWS in about 77% of the study area decreased from 2003 to 2013. The total change volume of TWS is about 2915.6 × 108 m^3. The areas of decreased TWS are mainly distributed in the middle of Central Asia, while the areas of increased TWS are concentrated in the middle-altitude regions of the Kazakhstan hills and Tarim Basin.(2) TWS in about 5.91% of areas, mainly distributed in the mountain and piedmont zones, is significantly positively correlated with precipitation, while only 3.78% of areas show significant correlation between TWS and temperature. If the response time was delayed by three months, there would be a very good correlation between temperature and TWS.(3) There is a significantly positive relationship between TWS and Normalized Difference Vegetation Index(NDVI) in 13.35% of the study area.(4) The area of significantly positive correlation between TWS and evapotranspiration is about 31.87%, mainly situated in mountainous areas and northwestern Kazakhstan. The reduction of regional TWS is related to precipitation more than evaporation. Increasing farmland area may explain why some areas show increasing precipitation and decreasing evapotranspiration.(5) The influences of land use on TWS are still not very clear. This study could provide scientific data useful for the estimation of changes in TWS with climate change and human activities.
基金financially supported by the National Natural Science Foundation of China (51664012)Guangxi Natural Science Foundation (2017GXNSFAA198117 and2015GXNSFGA139006)the Technology Major Project of Guangxi(AA19046001)
文摘A fundamental understanding of the electrochemical reaction process and mechanism of electrodes is very crucial for developing high-performance electrode materials.In this study,we report the sodium ion storage behavior and mechanism of orthorhombic V_(2)O_(5) single-crystalline nanowires in the voltage window of 1.0–4.0 V(vs.Na/Na+).The single-crystalline nanowires exhibit a large irreversible capacity loss during the first discharge/charge cycle,and then show excellent cycling stability in the following cycles.At a current density of 100 mA g^(−1),the nanowires electrode delivers initial discharge/charge capacity of 217/88 mA h g^(−1),corresponding to a Coulombic efficiency of only 40.5%;after 100 cycles,the electrode remains a reversible discharge capacity of 78 mA h g^(−1) with a fading rate of only 0.09%per cycle compared with the 2nd cycle discharge capacity.The sodium ion storage mechanism was investigated,illustrating that the large irreversible capacity loss in the first cycle can be attributed to the initially formed single-crystalline α′-Nax V_(2)O_(5)(0.02<x<0.88),in which sodium ions cannot be electrochemically extracted and the α′-Na0.88 V_(2)O_(5) can reversibly host and release sodium ions via a single-phase(solid solution)reaction,leading to excellent cycling stability.The Na^(+) diffusion coefficient in α′-Nax V_(2)O_(5) ranges from 10^(−12) to 10^(−11.5) cm^(2) s^(−1) as evaluated by galvanostatic intermittent titration technique(GITT).
