A two-staged membrane separation process for hydrogen recovery from refinery gases is introduced. The principle of the gas membrane separation process and the influence of the operation temperatures are analyzed. As t...A two-staged membrane separation process for hydrogen recovery from refinery gases is introduced. The principle of the gas membrane separation process and the influence of the operation temperatures are analyzed. As the conventional PID controller is difficult to make the operation temperatures steady, a fuzzy self-tuning PID control algorithm is proposed. The application shows that the algorithm is effective, the operation temperatures of both stages can be controlled steadily, and the operation flexibility and adaptability of the hydrogen recovery unit are enhanced with safety. This study lays a foundation to optimize the control of the membrane separation process and thus ensure the membrane performance.展开更多
Here in this paper,we report a room-temperature operating infrared photodetector based on the interband transition of an In As Sb/Ga Sb quantum well.The interband transition energy of 5-nm thick In As（0.91）Sb（0.09...Here in this paper,we report a room-temperature operating infrared photodetector based on the interband transition of an In As Sb/Ga Sb quantum well.The interband transition energy of 5-nm thick In As（0.91）Sb（0.09） embedded in the Ga Sb barrier is calculated to be 0.53 e V（2.35μm）,which makes the absorption range of In As Sb cover an entire range from short-wavelength infrared to long-wavelength infrared spectrum.The fabricated photodetector exhibits a narrow response range from 2.0μm to 2.3μm with a peak around 2.1μm at 300 K.The peak responsivity is 0.4 A/W under-500-m Vapplied bias voltage,corresponding to a peak quantum efficiency of 23.8%in the case without any anti-reflection coating.At 300 K,the photodetector exhibits a dark current density of 6.05×10^-3A/cm^2 under-400-m V applied bias voltage and 3.25×10^-5A/cm^2 under zero,separately.The peak detectivity is 6.91×10^10cm·Hz^1/2/W under zero bias voltage at 300 K.展开更多
A summer-time shipboard meteorological survey is described in the Northwest Indian Ocean. Shipboard observations are used to evaluate a satellite-based sea surface temperature（SST）, and then find the main factors th...A summer-time shipboard meteorological survey is described in the Northwest Indian Ocean. Shipboard observations are used to evaluate a satellite-based sea surface temperature（SST）, and then find the main factors that are highly correlated with errors. Two satellite data, the first is remote sensing product of a microwave, which is a Tropical Rainfall Measuring Mission Microwave Imager（TMI）, and the second is merged data from the microwave and infrared satellite as well as drifter observations, which is Operational Sea Surface Temperature and Sea Ice Analysis（OSTIA）. The results reveal that the daily mean SST of merged data has much lower bias and root mean square error as compared with that from microwave products. Therefore the results support the necessary of the merging infrared and drifter SST with a microwave satellite for improving the quality of the SST. Furthermore, the correlation coefficient between an SST error and meteorological parameters, which include a wind speed, an air temperature, a relative humidity, an air pressure, and a visibility. The results show that the wind speed has the largest correlation coefficient with the TMI SST error. However, the air temperature is the most important factor to the OSTIA SST error. Meanwhile,the relative humidity shows the high correlation with the SST error for the OSTIA product.展开更多
Currently,developing supercapacitors with robust cycle stability and suitability for wide-temperature-range operations is still a huge challenge.In the present work,few-layer hexagonal boron nitride nanosheets(h-BNNSs...Currently,developing supercapacitors with robust cycle stability and suitability for wide-temperature-range operations is still a huge challenge.In the present work,few-layer hexagonal boron nitride nanosheets(h-BNNSs)with a thickness of 2−4 atomic layers were fabricated via vacuum freeze-drying and nitridation.Then,the h-BNNSs/reduced graphene oxide(rGO)composite were further prepared using a hydrothermal method.Due to the combination of two two-dimensional(2D)van der Waals-bonded materials,the as-prepared h-BNNSs/rGO electrode exhibited robustness to wide-temperature-range operations from−10 to 50℃.When the electrodes worked in a neutral aqueous electrolyte(1 M Na2SO4),they showed a great stable cycling performance with almost 107%reservation of the initial capacitance at 0℃ and 111% at 50℃ for 5000 charge−discharge cycles.展开更多
Bi3.15Nd0.85Ti3O12 (BNdT) films were deposited on Pt/Ti/SiO2/Si(100) substrates by a metal organic decomposition (MOD)method, and annealed by a rapid thermal annealing process in oxygen atmosphere and in air, respecti...Bi3.15Nd0.85Ti3O12 (BNdT) films were deposited on Pt/Ti/SiO2/Si(100) substrates by a metal organic decomposition (MOD)method, and annealed by a rapid thermal annealing process in oxygen atmosphere and in air, respectively. The crystalline structuresand morphologies of BNdT films were characterized by X-ray diffraction and field-emission scanning electron microscopy, and thegas sensing properties were measured by monitoring its resistance at different gas concentrations. The results indicate that the BNdTfilms annealed in air are of porous microstructure and rough surface, and the annealing atmosphere has great influence on gas sensingproperties. At an operating temperature of 100 °C, the BNdT films annealed in air are of high response value to 1×10?6 gaseousethanol, and the detecting limit is as low as 0.1×10?6. The corresponding response and recovery time is about 10 and 6 s, respectively.The results can offer useful guidelines for fabricating high performance ethanol sensors.展开更多
Operating temperature of proton exchange membrane fuel cell stack should be controlled within a special range. The input-output data and operating experiences were used to establish a PEMFC stack model and operating t...Operating temperature of proton exchange membrane fuel cell stack should be controlled within a special range. The input-output data and operating experiences were used to establish a PEMFC stack model and operating temperature control system. A nonlinear predictive control algorithm based on fuzzy model was presented for a family of complex system with severe nonlinearity such as PEMFC. Based on the obtained fuzzy model, a discrete optimization of the control action was carried out according to the principle of Branch and Bound method. The test results demonstrate the effectiveness and advantage of this approach.展开更多
Purpose–This study aims to improve the availability of regenerative braking for urban metro vehicles by introducing a sensorless operational temperature estimation method for the braking resistor(BR)onboard the vehic...Purpose–This study aims to improve the availability of regenerative braking for urban metro vehicles by introducing a sensorless operational temperature estimation method for the braking resistor(BR)onboard the vehicle,which overcomes the vulnerability of having conventional temperature sensor.Design/methodology/approach–In this study,the energy model based sensorless estimation method is developed.By analyzing the structure and the convection dissipation process of the BR onboard the vehicle,the energy-based operational temperature model of the BR and its cooling domain is established.By adopting Newton’s law of cooling and the law of conservation of energy,the energy and temperature dynamic of the BR can be stated.To minimize the use of all kinds of sensors(including both thermal and electrical),a novel regenerative braking power calculation method is proposed,which involves only the voltage of DC traction network and the duty cycle of the chopping circuit;both of them are available for the traction control unit(TCU)of the vehicle.By utilizing a real-time iterative calculation and updating the parameter of the energy model,the operational temperature of the BR can be obtained and monitored in a sensorless manner.Findings–In this study,a sensorless estimation/monitoring method of the operational temperature of BR is proposed.The results show that it is possible to utilize the existing electrical sensors that is mandatory for the traction unit’s operation to estimate the operational temperature of BR,instead of adding dedicated thermal sensors.The results also validate the effectiveness of the proposal is acceptable for the engineering practical.Originality/value–The proposal of this study provides novel concepts for the sensorless operational temperature monitoring of BR onboard rolling stocks.The proposed method only involves quasi-global electrical variable and the internal control signal within the TCU.展开更多
We present a detailed study of λ- 9.75 μm GaAs/AlGaAs quantum cascade lasers. For a coated 2-rmm-long and 40-μm-wide laser, an optical power of 85 μ W is observed at 95% duty cycle at 80K. At a moderate driving pu...We present a detailed study of λ- 9.75 μm GaAs/AlGaAs quantum cascade lasers. For a coated 2-rmm-long and 40-μm-wide laser, an optical power of 85 μ W is observed at 95% duty cycle at 80K. At a moderate driving pulse （1 kHz and 1% duty cycle）,the device presents a peak power more than 20mW even at 120K. At 80K, the fitted result of threshold current densities shows evidence of potential cw operation.展开更多
This work falls within the context of reducing energy consumption in Côte d’Ivoire. As the building sector is one of the energy consumers worldwide, it could be a major source of energy savings. A major source o...This work falls within the context of reducing energy consumption in Côte d’Ivoire. As the building sector is one of the energy consumers worldwide, it could be a major source of energy savings. A major source of energy savings. With this in mind thermal comfort in buildings in Côte d’Ivoire (Abidjan) in order to determine (Abidjan) to determine thermal comfort conditions. To carry out study, measurement campaigns were carried out in various buildings. These measured parameters were used to calculate comfort indices such as PMV, PDD, SET and operating temperature. A correlation was then made between the PMV index and the operating temperature, then between the SET and the operating temperature to determine the thermoneutrality temperature and the different thermal comfort thermal comfort ranges. The PMV gave a thermoneutrality temperature of 24.87˚C in the rainy season and a thermoneutrality temperature of 25.15˚C during the dry season. In addition, the SET gave comfort ranges, with values ranging from 23.23˚C to 25.70˚C in the rainy season and 23.35˚C to 26.08˚C in the dry season. In addition, the acceptability predicted by the PDD showed that in the rainy season, the premises were more acceptable than in the dry season.展开更多
提出了一种Ga Al As红外发光二极管自动温控RTS(Random Telegraph Signal)噪声测试新方法。通过分析Ga Al As IRLED的RTS噪声产生机理及特性,建立了Ga Al As IRLED的RTS噪声模型,设计了自动温控噪声测试系统。实验结果表明,该方法能准...提出了一种Ga Al As红外发光二极管自动温控RTS(Random Telegraph Signal)噪声测试新方法。通过分析Ga Al As IRLED的RTS噪声产生机理及特性,建立了Ga Al As IRLED的RTS噪声模型,设计了自动温控噪声测试系统。实验结果表明,该方法能准确的测量Ga Al As IRLED的RTS噪声,得到与噪声模型一致的结果,为Ga Al As IRLED可靠性的噪声表征提供了实验与理论依据。展开更多
文摘A two-staged membrane separation process for hydrogen recovery from refinery gases is introduced. The principle of the gas membrane separation process and the influence of the operation temperatures are analyzed. As the conventional PID controller is difficult to make the operation temperatures steady, a fuzzy self-tuning PID control algorithm is proposed. The application shows that the algorithm is effective, the operation temperatures of both stages can be controlled steadily, and the operation flexibility and adaptability of the hydrogen recovery unit are enhanced with safety. This study lays a foundation to optimize the control of the membrane separation process and thus ensure the membrane performance.
基金Project supported by the National Natural Science Foundation of China(Grant No.11574362)
文摘Here in this paper,we report a room-temperature operating infrared photodetector based on the interband transition of an In As Sb/Ga Sb quantum well.The interband transition energy of 5-nm thick In As（0.91）Sb（0.09） embedded in the Ga Sb barrier is calculated to be 0.53 e V（2.35μm）,which makes the absorption range of In As Sb cover an entire range from short-wavelength infrared to long-wavelength infrared spectrum.The fabricated photodetector exhibits a narrow response range from 2.0μm to 2.3μm with a peak around 2.1μm at 300 K.The peak responsivity is 0.4 A/W under-500-m Vapplied bias voltage,corresponding to a peak quantum efficiency of 23.8%in the case without any anti-reflection coating.At 300 K,the photodetector exhibits a dark current density of 6.05×10^-3A/cm^2 under-400-m V applied bias voltage and 3.25×10^-5A/cm^2 under zero,separately.The peak detectivity is 6.91×10^10cm·Hz^1/2/W under zero bias voltage at 300 K.
基金China Ocean Mineral Resources Research and Development Association Project under contract No.DY125-12-R-03the National Natural Science Foundation of China under contract Nos 41476021 and 41321004the Scientific Research Fund of Second Institute of Oceanography,State Oceanic Administration China under contract No.JT1205
文摘A summer-time shipboard meteorological survey is described in the Northwest Indian Ocean. Shipboard observations are used to evaluate a satellite-based sea surface temperature（SST）, and then find the main factors that are highly correlated with errors. Two satellite data, the first is remote sensing product of a microwave, which is a Tropical Rainfall Measuring Mission Microwave Imager（TMI）, and the second is merged data from the microwave and infrared satellite as well as drifter observations, which is Operational Sea Surface Temperature and Sea Ice Analysis（OSTIA）. The results reveal that the daily mean SST of merged data has much lower bias and root mean square error as compared with that from microwave products. Therefore the results support the necessary of the merging infrared and drifter SST with a microwave satellite for improving the quality of the SST. Furthermore, the correlation coefficient between an SST error and meteorological parameters, which include a wind speed, an air temperature, a relative humidity, an air pressure, and a visibility. The results show that the wind speed has the largest correlation coefficient with the TMI SST error. However, the air temperature is the most important factor to the OSTIA SST error. Meanwhile,the relative humidity shows the high correlation with the SST error for the OSTIA product.
基金financially supported by the National Natural Science Foundation for Excellent Young Scholars of China (No. 51522402)the National Postdoctoral Program for Innovative Talents of China (No. BX20180034)+2 种基金the National Natural Science Foundation of China (No. 51902020)the Fundamental Research Funds for the Central Universities (No. FRF-TP-18-045A1)the China Postdoctoral Science Foundation (No. 2018M641192)
文摘Currently,developing supercapacitors with robust cycle stability and suitability for wide-temperature-range operations is still a huge challenge.In the present work,few-layer hexagonal boron nitride nanosheets(h-BNNSs)with a thickness of 2−4 atomic layers were fabricated via vacuum freeze-drying and nitridation.Then,the h-BNNSs/reduced graphene oxide(rGO)composite were further prepared using a hydrothermal method.Due to the combination of two two-dimensional(2D)van der Waals-bonded materials,the as-prepared h-BNNSs/rGO electrode exhibited robustness to wide-temperature-range operations from−10 to 50℃.When the electrodes worked in a neutral aqueous electrolyte(1 M Na2SO4),they showed a great stable cycling performance with almost 107%reservation of the initial capacitance at 0℃ and 111% at 50℃ for 5000 charge−discharge cycles.
基金Project(51402250)supported by the National Natural Science Foundation of ChinaProject(2015JJ4046)supported by the Hunan Provincial Natural Science Foundation of ChinaProject(14B168)supported by the Scientific Research Fund of Hunan Provincial Education Department,China
文摘Bi3.15Nd0.85Ti3O12 (BNdT) films were deposited on Pt/Ti/SiO2/Si(100) substrates by a metal organic decomposition (MOD)method, and annealed by a rapid thermal annealing process in oxygen atmosphere and in air, respectively. The crystalline structuresand morphologies of BNdT films were characterized by X-ray diffraction and field-emission scanning electron microscopy, and thegas sensing properties were measured by monitoring its resistance at different gas concentrations. The results indicate that the BNdTfilms annealed in air are of porous microstructure and rough surface, and the annealing atmosphere has great influence on gas sensingproperties. At an operating temperature of 100 °C, the BNdT films annealed in air are of high response value to 1×10?6 gaseousethanol, and the detecting limit is as low as 0.1×10?6. The corresponding response and recovery time is about 10 and 6 s, respectively.The results can offer useful guidelines for fabricating high performance ethanol sensors.
文摘Operating temperature of proton exchange membrane fuel cell stack should be controlled within a special range. The input-output data and operating experiences were used to establish a PEMFC stack model and operating temperature control system. A nonlinear predictive control algorithm based on fuzzy model was presented for a family of complex system with severe nonlinearity such as PEMFC. Based on the obtained fuzzy model, a discrete optimization of the control action was carried out according to the principle of Branch and Bound method. The test results demonstrate the effectiveness and advantage of this approach.
基金supported by the Fund of China Academy of Railway Sciences Corporation Limited(2022YJ230)the Scientific Research Projects of China Association of Metros(CAMET-KY-2022039).
文摘Purpose–This study aims to improve the availability of regenerative braking for urban metro vehicles by introducing a sensorless operational temperature estimation method for the braking resistor(BR)onboard the vehicle,which overcomes the vulnerability of having conventional temperature sensor.Design/methodology/approach–In this study,the energy model based sensorless estimation method is developed.By analyzing the structure and the convection dissipation process of the BR onboard the vehicle,the energy-based operational temperature model of the BR and its cooling domain is established.By adopting Newton’s law of cooling and the law of conservation of energy,the energy and temperature dynamic of the BR can be stated.To minimize the use of all kinds of sensors(including both thermal and electrical),a novel regenerative braking power calculation method is proposed,which involves only the voltage of DC traction network and the duty cycle of the chopping circuit;both of them are available for the traction control unit(TCU)of the vehicle.By utilizing a real-time iterative calculation and updating the parameter of the energy model,the operational temperature of the BR can be obtained and monitored in a sensorless manner.Findings–In this study,a sensorless estimation/monitoring method of the operational temperature of BR is proposed.The results show that it is possible to utilize the existing electrical sensors that is mandatory for the traction unit’s operation to estimate the operational temperature of BR,instead of adding dedicated thermal sensors.The results also validate the effectiveness of the proposal is acceptable for the engineering practical.Originality/value–The proposal of this study provides novel concepts for the sensorless operational temperature monitoring of BR onboard rolling stocks.The proposed method only involves quasi-global electrical variable and the internal control signal within the TCU.
基金Supported by the National Natural Science Foundation of China for Distinguished Young Scholars （60525406）, the General Programme and Key Programme of the National Natural Since Foundation of China （90101002 and 60136010）, the Special Fund for Major State Basics Research Project of China （G20000683-2）, and National High Technology Programs of China （2001AA311140 and 2005AA31G040）.
文摘We present a detailed study of λ- 9.75 μm GaAs/AlGaAs quantum cascade lasers. For a coated 2-rmm-long and 40-μm-wide laser, an optical power of 85 μ W is observed at 95% duty cycle at 80K. At a moderate driving pulse （1 kHz and 1% duty cycle）,the device presents a peak power more than 20mW even at 120K. At 80K, the fitted result of threshold current densities shows evidence of potential cw operation.
文摘This work falls within the context of reducing energy consumption in Côte d’Ivoire. As the building sector is one of the energy consumers worldwide, it could be a major source of energy savings. A major source of energy savings. With this in mind thermal comfort in buildings in Côte d’Ivoire (Abidjan) in order to determine (Abidjan) to determine thermal comfort conditions. To carry out study, measurement campaigns were carried out in various buildings. These measured parameters were used to calculate comfort indices such as PMV, PDD, SET and operating temperature. A correlation was then made between the PMV index and the operating temperature, then between the SET and the operating temperature to determine the thermoneutrality temperature and the different thermal comfort thermal comfort ranges. The PMV gave a thermoneutrality temperature of 24.87˚C in the rainy season and a thermoneutrality temperature of 25.15˚C during the dry season. In addition, the SET gave comfort ranges, with values ranging from 23.23˚C to 25.70˚C in the rainy season and 23.35˚C to 26.08˚C in the dry season. In addition, the acceptability predicted by the PDD showed that in the rainy season, the premises were more acceptable than in the dry season.
文摘提出了一种Ga Al As红外发光二极管自动温控RTS(Random Telegraph Signal)噪声测试新方法。通过分析Ga Al As IRLED的RTS噪声产生机理及特性,建立了Ga Al As IRLED的RTS噪声模型,设计了自动温控噪声测试系统。实验结果表明,该方法能准确的测量Ga Al As IRLED的RTS噪声,得到与噪声模型一致的结果,为Ga Al As IRLED可靠性的噪声表征提供了实验与理论依据。
