Air flow control is one of the most important control methods for maintaining the stability and reliability of a fuel cell system, which can avoid oxygen starvation or oxygen saturation. The oxygen excess ratio （OER...Air flow control is one of the most important control methods for maintaining the stability and reliability of a fuel cell system, which can avoid oxygen starvation or oxygen saturation. The oxygen excess ratio （OER） is often used to indicate the air flow condition. Based on a fuel cell system model for vehicles, OER performance was analyzed for different stack currents and temperatures in this paper, and the results show that the optimal OER was affected weakly by the stack temperature. In order to ensure the system working in optimal OER, a control scheme that includes an optimal OER regulator and a fuzzy control was proposed. According to the stack current, a reference value of air flow rate was obtained with the optimal OER regulator and then the air compressor motor voltage was controlled with the fuzzy controller to adjust the air flow rate provided by the air compressor. Simulation results show that the control method has good dynamic and static characteristics.展开更多
A complete control type plant factory has high efficiency in terms of cultivation area by constructing vertical multiple layered cultivation beds.However,it has a problem of irregular crop growth due to temperature de...A complete control type plant factory has high efficiency in terms of cultivation area by constructing vertical multiple layered cultivation beds.However,it has a problem of irregular crop growth due to temperature deviation at upper and lower beds and increases in energy consumption by a prolonged cultivation period.In this work,air flow rate inside a facility was improved by a hybrid control of air flow devices like air conditioning and air circulation fan with an established wireless sensor network to minimize temperature deviations between upper and lower beds and to promote crop growth.The performance of proposed system was verified with an experimental environment or Case A wherein air conditioning device was operated without a control algorithm and Case B wherein air conditioning and circulation fans were alternatively operated based on the hybrid control algorithm.After planting leafy vegetables under each experimental condition,crops were cultivated for 21 days.As a result,Case B wherein AC(air conditioning) and ACF(air-circulation fan) were alternatively operated based on the hybrid control algorithm showed that fresh mass,number of leaves,and leaf length for the crops grown were increased by 40.6%,41.1%,and 11.1%,respectively,compared to Case A.展开更多
A time-optimal aircraft-following model is introduced to address air traffic flow interference by velocity reduction. The objective function is set up as minimizing the recovery time during which the separation minima...A time-optimal aircraft-following model is introduced to address air traffic flow interference by velocity reduction. The objective function is set up as minimizing the recovery time during which the separation minima are not infringed and the separation of the air traffic flow returns to the initial separation at the terminal time. Pontryagin＇s minimum principle is used to solve the optimum aircraft-following velocity control law. An analytical minimum safe following separation is also provided under the time-optimal control law. The simulation results show that the precision first-order tracking accuracy is achieved without losing the separation.展开更多
航路交叉口的管制调配一直是影响空管效率的核心问题,以往研究多是针对少量架次航空器进行分析,本论文在航迹运行(trajectory based operations,TBO)环境下,基于自主改航对航路交叉口处交叉航班流的预先冲突解脱方法进行研究.首先,基于...航路交叉口的管制调配一直是影响空管效率的核心问题,以往研究多是针对少量架次航空器进行分析,本论文在航迹运行(trajectory based operations,TBO)环境下,基于自主改航对航路交叉口处交叉航班流的预先冲突解脱方法进行研究.首先,基于航空器间水平安全间隔,转换计算航空器过交叉口时应保持的最小纵向时间间隔;其次,提出占用时间窗概念,建立基于占用时间窗的冲突检测模型,并考虑航班流通过时间最短制定综合通行原则,判定冲突中需要改航的航空器;最后,针对航班流通行中传统启发式算法时效性不足的问题,利用转弯角限制缩减可行解空间,并建立以改航时间最短为目标的改航点搜索模型,提高求解速度和搜索精度.以我国东北部典型高空扇区为例,验证所提方法在实际交叉航路运行下的有效性.仿真结果表明:所提冲突解脱方法的多米诺效应指数(domino effect parameter,DEP)相较于传统等待解脱方法降低了64.7%,且传统方法的解脱总用时为所提冲突解脱方法的7.6倍,所提解脱方法对空域稳定性的影响更小,解脱效率更高.展开更多
This paper puts forward a novel concept, the spatial flow influence factor (SFIF), which provides a new insight into the airflow structure. This concept is very helpful in the control of indoor air pollutants since: (...This paper puts forward a novel concept, the spatial flow influence factor (SFIF), which provides a new insight into the airflow structure. This concept is very helpful in the control of indoor air pollutants since: (1) for a given indoor airflow; given sources of volatile organic compounds (VOCs), the optimal arrangement of the VOC sources can easily be obtained; (2) for given positions of VOC sources; occupied regions (or target regions), the optimal indoor airflow pattern or organization can be determined; (3) the SFIF for an indoor space can also be regarded as the indoor air safety index of that space. To illustrate this concept, we present several examples of applying a SFIF to indoor air VOC control.展开更多
基金supported by the National Natural Science Foundation of China (No. 51177138)the Research Fund for the Doctoral Program of High Education of China (No.20100184110015)Sichuan Province International Technology Cooperation and Exchange Program (No. 2012HH0007)
文摘Air flow control is one of the most important control methods for maintaining the stability and reliability of a fuel cell system, which can avoid oxygen starvation or oxygen saturation. The oxygen excess ratio （OER） is often used to indicate the air flow condition. Based on a fuel cell system model for vehicles, OER performance was analyzed for different stack currents and temperatures in this paper, and the results show that the optimal OER was affected weakly by the stack temperature. In order to ensure the system working in optimal OER, a control scheme that includes an optimal OER regulator and a fuzzy control was proposed. According to the stack current, a reference value of air flow rate was obtained with the optimal OER regulator and then the air compressor motor voltage was controlled with the fuzzy controller to adjust the air flow rate provided by the air compressor. Simulation results show that the control method has good dynamic and static characteristics.
基金Work(NRF-2012H1B8A2026145)supported by the Human Resource Training Program for Regional Innovation through the Ministry of Education and National Research Foundation of KoreaProject(2015K000281)supported by the Functional Districts of the Science Belt Support Program,Ministry of Science,ICT and Future Planning,Korea
文摘A complete control type plant factory has high efficiency in terms of cultivation area by constructing vertical multiple layered cultivation beds.However,it has a problem of irregular crop growth due to temperature deviation at upper and lower beds and increases in energy consumption by a prolonged cultivation period.In this work,air flow rate inside a facility was improved by a hybrid control of air flow devices like air conditioning and air circulation fan with an established wireless sensor network to minimize temperature deviations between upper and lower beds and to promote crop growth.The performance of proposed system was verified with an experimental environment or Case A wherein air conditioning device was operated without a control algorithm and Case B wherein air conditioning and circulation fans were alternatively operated based on the hybrid control algorithm.After planting leafy vegetables under each experimental condition,crops were cultivated for 21 days.As a result,Case B wherein AC(air conditioning) and ACF(air-circulation fan) were alternatively operated based on the hybrid control algorithm showed that fresh mass,number of leaves,and leaf length for the crops grown were increased by 40.6%,41.1%,and 11.1%,respectively,compared to Case A.
基金supported by the National Natural Science Foundations of China (Nos. 60972006 and61179042)the National Science and Technology Support Program (No. 2011BAH24B10)
文摘A time-optimal aircraft-following model is introduced to address air traffic flow interference by velocity reduction. The objective function is set up as minimizing the recovery time during which the separation minima are not infringed and the separation of the air traffic flow returns to the initial separation at the terminal time. Pontryagin＇s minimum principle is used to solve the optimum aircraft-following velocity control law. An analytical minimum safe following separation is also provided under the time-optimal control law. The simulation results show that the precision first-order tracking accuracy is achieved without losing the separation.
文摘航路交叉口的管制调配一直是影响空管效率的核心问题,以往研究多是针对少量架次航空器进行分析,本论文在航迹运行(trajectory based operations,TBO)环境下,基于自主改航对航路交叉口处交叉航班流的预先冲突解脱方法进行研究.首先,基于航空器间水平安全间隔,转换计算航空器过交叉口时应保持的最小纵向时间间隔;其次,提出占用时间窗概念,建立基于占用时间窗的冲突检测模型,并考虑航班流通过时间最短制定综合通行原则,判定冲突中需要改航的航空器;最后,针对航班流通行中传统启发式算法时效性不足的问题,利用转弯角限制缩减可行解空间,并建立以改航时间最短为目标的改航点搜索模型,提高求解速度和搜索精度.以我国东北部典型高空扇区为例,验证所提方法在实际交叉航路运行下的有效性.仿真结果表明:所提冲突解脱方法的多米诺效应指数(domino effect parameter,DEP)相较于传统等待解脱方法降低了64.7%,且传统方法的解脱总用时为所提冲突解脱方法的7.6倍,所提解脱方法对空域稳定性的影响更小,解脱效率更高.
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 50478012 and 50436040).
文摘This paper puts forward a novel concept, the spatial flow influence factor (SFIF), which provides a new insight into the airflow structure. This concept is very helpful in the control of indoor air pollutants since: (1) for a given indoor airflow; given sources of volatile organic compounds (VOCs), the optimal arrangement of the VOC sources can easily be obtained; (2) for given positions of VOC sources; occupied regions (or target regions), the optimal indoor airflow pattern or organization can be determined; (3) the SFIF for an indoor space can also be regarded as the indoor air safety index of that space. To illustrate this concept, we present several examples of applying a SFIF to indoor air VOC control.
