Rice farmers occupy a potentially important intersection between economics and hydrology in Northern California. While drought makes water an increasingly precious commodity across California, the monetary worth of wa...Rice farmers occupy a potentially important intersection between economics and hydrology in Northern California. While drought makes water an increasingly precious commodity across California, the monetary worth of water is not uniform across different localities and uses. As a result, circumstances have given many Sacramento Valley rice farmers the option to sell their water to users elsewhere, in lieu of using it themselves. Because the sold water is typically surface water that would normally help recharge local aquifers when applied to a field;it is reasonable to suspect that transferring that water elsewhere could adversely affect local aquifers since that recharge would be reduced. This study performs numerical experiments using the United States Geological Survey’s Central Valley Hydrologic Model (CVHM) to better understand the temporal effects of a set of land idling scenarios. CVHM is capable of modeling the entire Central Valley, which encompasses the Sacramento and San Joaquin Valleys, and of representing rice field idling on a large scale. These experiments were executed using historical data to contrast recently typical amounts of rice field idling with scenarios reflecting varying degrees of hypothetical, increased idling. In doing so, this study aims to characterize the nature and potential magnitude of idling rice fields on groundwater storage in the Sacramento Valley. The impact of these scenarios on groundwater storage was quantified relative to an unaltered baseline model scenario. The results of this research show rice field idling will reduce recharge and groundwater storage levels;these results may provide useful information for future policy decisions and provide a basis for future study.展开更多
The relocity and sirain-rate .field which are different from Avilzur's have beenestablished in Caitesian coordinates. Using the integral as a function of the upper limitand integration depending on a parameler, an...The relocity and sirain-rate .field which are different from Avilzur's have beenestablished in Caitesian coordinates. Using the integral as a function of the upper limitand integration depending on a parameler, an analylical upper-bound solution todrawing stress through idling rolls has been obtained in this paper.展开更多
The intake air control system of a gasoline engine is a typical nonlinear system, and included among the adverse fac-tors that always induce poor idle-speed control stability are dead time and disturbances in the inta...The intake air control system of a gasoline engine is a typical nonlinear system, and included among the adverse fac-tors that always induce poor idle-speed control stability are dead time and disturbances in the intake air control process. In this paper, to improve the responsiveness when idling with regard to disturbances, a mean-value engine model (MVEM) with dead time was constructed as the control object, and the two servo structures of sliding mode control (SMC) were studied for better idle control performance, especially in transient process of speed change. The simulation results confirmed that under the constraint condition of control input, the robustness of idle speed control that is being subjected to torque disturbances and noise disturbances can be greatly improved by use of the servo structure II.展开更多
When the proton exchange membrane fuel cell(PEMFC)system is running,there will be a condition that does not require power output for a short time.In order to achieve zero power output under low power consumption,it is...When the proton exchange membrane fuel cell(PEMFC)system is running,there will be a condition that does not require power output for a short time.In order to achieve zero power output under low power consumption,it is necessary to consider the diversity of control targets and the complexity of dynamic models,which brings the challenge of high-precision tracking control of the stack output power and cathode intake flow.For system idle speed control,a modelbased nonlinear control framework is constructed in this paper.Firstly,the nonlinear dynamic model of output power and cathode intake flow is derived.Secondly,a control scheme combining nonlinear extended Kalman filter observer and state feedback controller is designed.Finally,the control scheme is verified on the PEMFC experimental platform and compared with the proportion-integration-differentiation(PID)controller.The experimental results show that the control strategy proposed in this paper can realize the idle speed control of the fuel cell system and achieve the purpose of zero power output.Compared with PID controller,it has faster response speed and better system dynamics.展开更多
With the acceleration of urban and rural development,the problem of rural idle residential land has become increasingly prominent,and its effective revitalization and utilization is of great significance for optimizin...With the acceleration of urban and rural development,the problem of rural idle residential land has become increasingly prominent,and its effective revitalization and utilization is of great significance for optimizing the allocation of land resources and promoting the sustainable development of rural economy.Based on the performance evaluation of the revitalization and utilization of rural idle residential land in previous studies,this paper discusses the theoretical framework and method system of the current evaluation system.This study first defines the concept connotations of rural idle residential land and their revitalization and utilization.It then summarizes the progress of domestic and international research on performance evaluation,and sorts out and explores the existing relevant research methods for land performance performance by domestic scholars,thereby making the reflective summary of the performance evaluation on the revitalization and utilization of rural idle residential land,and pointing out the possible future research direction.展开更多
On average, long-haul trucks in the U.S. use approximately 667 million gallons of fuel each year just for idling. This idling primarily facilitates climate control operations during driver rest periods. To mitigate th...On average, long-haul trucks in the U.S. use approximately 667 million gallons of fuel each year just for idling. This idling primarily facilitates climate control operations during driver rest periods. To mitigate this, our study explored ways to diminish the electrical consumption of climate control systems in class 8 trucks through innovative load reduction technologies. We utilized the CoolCalc software, developed by the National Renewable Energy Laboratory (NREL), which integrates heat transfer principles with extensive weather data from across the U.S. to mimic the environmental conditions trucks face year-round. The analysis of the CoolCalc simulations was performed using MATLAB. We assessed the impact of various technologies, including white paint, advanced curtains, and Thinsulate insulation on reducing electrical demand compared to standard conditions. Our findings indicate that trucks operating in the eastern U.S. could see electrical load reductions of up to 40%, while those in the western regions could achieve reductions as high as 55%. Such significant decreases in energy consumption mean that a 10 kWh battery system could sufficiently manage the HVAC needs of these trucks throughout the year without idling. Given that many long-haul trucks are equipped with battery systems of around 800 Ah (9.6 kWh), implementing these advanced technologies could substantially curtail the necessity for idling to power air conditioning systems.展开更多
Temperature rise caused by windage power is a major limitation to the large-scale process of geotechnical centrifuges.However,there is no consensus on how to identify the key parts(parts with high windage power consum...Temperature rise caused by windage power is a major limitation to the large-scale process of geotechnical centrifuges.However,there is no consensus on how to identify the key parts(parts with high windage power consumption)and parameters(the velocity coefficientαand windage coefficient C_(i)),and the influence of idle power is often neglected in methods for calculating windage power.To address these issues,a Centrifugal Hypergravity and Interdisciplinary Experiment Facility(CHIEF)scaled model device was constructed,and the windage power was measured.Then,a computational fluid dynamics(CFD)model of the device was established and validated by experimental results.Simulation results were analyzed to quantify the proportion of the windage power in different parts of the device and summarize the variation law of key parameters.Finally,a novel windage power calculation equation was developed based on the elimination of the influence of the idle power.Results show that the role of the rotating arm cannot be ignored in the selection of key parts.The velocity coefficient and windage coefficient are a function of the device geometry and size,and are independent of the angular velocity.The windage power is proportional to the cube of the angular velocity after eliminating the effect of idle power.展开更多
The paper sheds light on the idle lean blow off(LBO)problem for high fuel air ratio(FAR)com⁃bustor,which is impossible to be addressed with traditional aero combustor design.A significant improvement in aero combustor...The paper sheds light on the idle lean blow off(LBO)problem for high fuel air ratio(FAR)com⁃bustor,which is impossible to be addressed with traditional aero combustor design.A significant improvement in aero combustor design is required to resolve the idle LBO issue.The authors detailed a practical and efficient solu⁃tion,which not only solved the idle LBO issue but also defined the aero-thermal design for high-FAR combustor.The design will usher in a new era of aero combustor.展开更多
秸秆焚烧容易污染空气,影响交通。常规秸秆焚烧监测难度较大,而卫星遥感数据具有覆盖面广,时效性强、分辨率高等优点,有利于秸秆焚烧监测工作的进展。本文将介绍如何使用MODIS数据提取秸秆焚烧火点的算法。在算法实现上采用交互式数据语...秸秆焚烧容易污染空气,影响交通。常规秸秆焚烧监测难度较大,而卫星遥感数据具有覆盖面广,时效性强、分辨率高等优点,有利于秸秆焚烧监测工作的进展。本文将介绍如何使用MODIS数据提取秸秆焚烧火点的算法。在算法实现上采用交互式数据语言IDL(Interactive Data Language)进行实现,大大缩短了人机交互时间,提高了秸秆焚烧点自动提取的响应速度,从而提高工作效率,促进秸秆焚烧监测工作的开展。展开更多
文摘Rice farmers occupy a potentially important intersection between economics and hydrology in Northern California. While drought makes water an increasingly precious commodity across California, the monetary worth of water is not uniform across different localities and uses. As a result, circumstances have given many Sacramento Valley rice farmers the option to sell their water to users elsewhere, in lieu of using it themselves. Because the sold water is typically surface water that would normally help recharge local aquifers when applied to a field;it is reasonable to suspect that transferring that water elsewhere could adversely affect local aquifers since that recharge would be reduced. This study performs numerical experiments using the United States Geological Survey’s Central Valley Hydrologic Model (CVHM) to better understand the temporal effects of a set of land idling scenarios. CVHM is capable of modeling the entire Central Valley, which encompasses the Sacramento and San Joaquin Valleys, and of representing rice field idling on a large scale. These experiments were executed using historical data to contrast recently typical amounts of rice field idling with scenarios reflecting varying degrees of hypothetical, increased idling. In doing so, this study aims to characterize the nature and potential magnitude of idling rice fields on groundwater storage in the Sacramento Valley. The impact of these scenarios on groundwater storage was quantified relative to an unaltered baseline model scenario. The results of this research show rice field idling will reduce recharge and groundwater storage levels;these results may provide useful information for future policy decisions and provide a basis for future study.
文摘The relocity and sirain-rate .field which are different from Avilzur's have beenestablished in Caitesian coordinates. Using the integral as a function of the upper limitand integration depending on a parameler, an analylical upper-bound solution todrawing stress through idling rolls has been obtained in this paper.
文摘The intake air control system of a gasoline engine is a typical nonlinear system, and included among the adverse fac-tors that always induce poor idle-speed control stability are dead time and disturbances in the intake air control process. In this paper, to improve the responsiveness when idling with regard to disturbances, a mean-value engine model (MVEM) with dead time was constructed as the control object, and the two servo structures of sliding mode control (SMC) were studied for better idle control performance, especially in transient process of speed change. The simulation results confirmed that under the constraint condition of control input, the robustness of idle speed control that is being subjected to torque disturbances and noise disturbances can be greatly improved by use of the servo structure II.
基金Supported by the Major Science and Technology Projects in Jilin Province and Changchun City(20220301010GX).
文摘When the proton exchange membrane fuel cell(PEMFC)system is running,there will be a condition that does not require power output for a short time.In order to achieve zero power output under low power consumption,it is necessary to consider the diversity of control targets and the complexity of dynamic models,which brings the challenge of high-precision tracking control of the stack output power and cathode intake flow.For system idle speed control,a modelbased nonlinear control framework is constructed in this paper.Firstly,the nonlinear dynamic model of output power and cathode intake flow is derived.Secondly,a control scheme combining nonlinear extended Kalman filter observer and state feedback controller is designed.Finally,the control scheme is verified on the PEMFC experimental platform and compared with the proportion-integration-differentiation(PID)controller.The experimental results show that the control strategy proposed in this paper can realize the idle speed control of the fuel cell system and achieve the purpose of zero power output.Compared with PID controller,it has faster response speed and better system dynamics.
文摘With the acceleration of urban and rural development,the problem of rural idle residential land has become increasingly prominent,and its effective revitalization and utilization is of great significance for optimizing the allocation of land resources and promoting the sustainable development of rural economy.Based on the performance evaluation of the revitalization and utilization of rural idle residential land in previous studies,this paper discusses the theoretical framework and method system of the current evaluation system.This study first defines the concept connotations of rural idle residential land and their revitalization and utilization.It then summarizes the progress of domestic and international research on performance evaluation,and sorts out and explores the existing relevant research methods for land performance performance by domestic scholars,thereby making the reflective summary of the performance evaluation on the revitalization and utilization of rural idle residential land,and pointing out the possible future research direction.
文摘On average, long-haul trucks in the U.S. use approximately 667 million gallons of fuel each year just for idling. This idling primarily facilitates climate control operations during driver rest periods. To mitigate this, our study explored ways to diminish the electrical consumption of climate control systems in class 8 trucks through innovative load reduction technologies. We utilized the CoolCalc software, developed by the National Renewable Energy Laboratory (NREL), which integrates heat transfer principles with extensive weather data from across the U.S. to mimic the environmental conditions trucks face year-round. The analysis of the CoolCalc simulations was performed using MATLAB. We assessed the impact of various technologies, including white paint, advanced curtains, and Thinsulate insulation on reducing electrical demand compared to standard conditions. Our findings indicate that trucks operating in the eastern U.S. could see electrical load reductions of up to 40%, while those in the western regions could achieve reductions as high as 55%. Such significant decreases in energy consumption mean that a 10 kWh battery system could sufficiently manage the HVAC needs of these trucks throughout the year without idling. Given that many long-haul trucks are equipped with battery systems of around 800 Ah (9.6 kWh), implementing these advanced technologies could substantially curtail the necessity for idling to power air conditioning systems.
基金supported by the National Major Science and Technology Infrastructure Project of China(No.2017-000052-73-01-002083)the Information Technology Center,Zhejiang University,China.
文摘Temperature rise caused by windage power is a major limitation to the large-scale process of geotechnical centrifuges.However,there is no consensus on how to identify the key parts(parts with high windage power consumption)and parameters(the velocity coefficientαand windage coefficient C_(i)),and the influence of idle power is often neglected in methods for calculating windage power.To address these issues,a Centrifugal Hypergravity and Interdisciplinary Experiment Facility(CHIEF)scaled model device was constructed,and the windage power was measured.Then,a computational fluid dynamics(CFD)model of the device was established and validated by experimental results.Simulation results were analyzed to quantify the proportion of the windage power in different parts of the device and summarize the variation law of key parameters.Finally,a novel windage power calculation equation was developed based on the elimination of the influence of the idle power.Results show that the role of the rotating arm cannot be ignored in the selection of key parts.The velocity coefficient and windage coefficient are a function of the device geometry and size,and are independent of the angular velocity.The windage power is proportional to the cube of the angular velocity after eliminating the effect of idle power.
文摘The paper sheds light on the idle lean blow off(LBO)problem for high fuel air ratio(FAR)com⁃bustor,which is impossible to be addressed with traditional aero combustor design.A significant improvement in aero combustor design is required to resolve the idle LBO issue.The authors detailed a practical and efficient solu⁃tion,which not only solved the idle LBO issue but also defined the aero-thermal design for high-FAR combustor.The design will usher in a new era of aero combustor.
文摘秸秆焚烧容易污染空气,影响交通。常规秸秆焚烧监测难度较大,而卫星遥感数据具有覆盖面广,时效性强、分辨率高等优点,有利于秸秆焚烧监测工作的进展。本文将介绍如何使用MODIS数据提取秸秆焚烧火点的算法。在算法实现上采用交互式数据语言IDL(Interactive Data Language)进行实现,大大缩短了人机交互时间,提高了秸秆焚烧点自动提取的响应速度,从而提高工作效率,促进秸秆焚烧监测工作的开展。
