Finding the optimal control is of importance to quantum metrology under a noisy environment.In this paper,we tackle the problem of finding the optimal control to enhance the performance of quantum metrology under an a...Finding the optimal control is of importance to quantum metrology under a noisy environment.In this paper,we tackle the problem of finding the optimal control to enhance the performance of quantum metrology under an arbitrary non-Markovian bosonic environment.By introducing an equivalent pseudomode model,the non-Markovian dynamic evolution is reduced to a Lindblad master equation,which helps us to calculate the gradient of quantum Fisher information and perform the gradient ascent algorithm to find the optimal control.Our approach is accurate and circumvents the need for the Born-Markovian approximation.As an example,we consider the frequency estimation of a spin with pure dephasing under two types of non-Markovian environments.By maximizing the quantum Fisher information at a fixed evolution time,we obtain the optimal multi-axis control,which results in a notable enhancement in quantum metrology.The advantage of our method lies in its applicability to the arbitrary non-Markovian bosonic environment.展开更多
To effectively select risk control schemes in uncertain environments,this paper has proposed an analysis and evaluation method based on the fuzzy comprehensive evaluation method.Firstly,enterprises have adopted the br...To effectively select risk control schemes in uncertain environments,this paper has proposed an analysis and evaluation method based on the fuzzy comprehensive evaluation method.Firstly,enterprises have adopted the brainstorming method and the Delphi method to identify risks in engineering projects,and organized the identified risks in the form of checklists to facilitate further analysis.Secondly,the fuzzy comprehensive evaluation theory was introduced to determine the comparison matrix of each risk factor and its weight.Furthermore,the top five risk factors in terms of weight ranking were taken as the evaluation factors for the selection of risk control plans.The plans were scored through the weighted scoring method,and the optimal risk control plan was determined based on the score.Finally,the feasibility of the proposed selection technology was verified through A research example of the risk control plan assessment for the construction project of Enterprise A.展开更多
This paper presents a thermophysical study approach for a pure environmental control system(ECS),incorporating the geometric dimensions of heat exchangers,ram air duct,and air cycle machine(ACM)blades of the Sabreline...This paper presents a thermophysical study approach for a pure environmental control system(ECS),incorporating the geometric dimensions of heat exchangers,ram air duct,and air cycle machine(ACM)blades of the Sabreliner’s environmental control system.Real flight scenarios are simulated by considering flight input variables such as altitude,aircraft speed,compression ratio of the air cycle machine,and the mass flow rate of bleed air.The study evaluates the coefficient of performance(COP)of the environmental control system,the heat exchanger efficiencies,and the work distribution of the air cycle machine based on five flight scenarios,with a particular focus on considering the effects of humidity on environmental control system performance.The results demonstrate that at cruising altitude(11,000 m),air humidity conditions allow an increase in the COP of around 9.28%compared to dry conditions.Conversely,on land,humidity conditions reduce the performance by 4.26%compared to dry conditions.It was also found that the effects of humidity at high aircraft speeds become negligible.In general terms,the humidity conditions in the air proved to have positive effects on the environmental control system’s performance but negative effects on the heat exchanger efficiencies,reducing them by 0.22%.Additionally,land conditions reflect significant improvements in performance when the compression ratio of the air cycle machine is varied.Furthermore,in the work distribution of the air cycle machine,humidity conditions were demonstrated to consume 2.91%less work fromthe turbine compared to dry conditions.展开更多
In recent years,formation control of multi-agent has been a significant research subject in the field of cooperative control.However,previous works have mainly concentrated on formation control for simple point-mass m...In recent years,formation control of multi-agent has been a significant research subject in the field of cooperative control.However,previous works have mainly concentrated on formation control for simple point-mass model and linear model.In contrast,this paper presents a novel cooperative algorithm for multiple air vehicles formation control,which aims to devise a control strategy based on guidance route to achieve precisely coordinated formation control for a group of fixed-wing aircraft in a complex task environment.The proposed method introduces the leader-follower structure for effective organization of the multi-agent coordination.Moreover,the Partial Integrated Formation and Control(PIFC)is adopted to design the control law for Guidance-Route based Formation Control(GRFC).Additionally,the proposed approach designs two guidance-route generation strategies for two special situations to demonstrate the effectiveness of GRFC in complex task environments.Theoretical analysis reveals that the proposed control protocol for guidance command can ensure the overall stability and tracking accuracy of the system.Numerical simulations are performed to illustrate the theoretical results,and verify that the proposed approach can achieve coordinated formation control precisely in a complex task environment.展开更多
To solve the problem of robust servo performance of Flight Environment Testbed(FET)of Altitude Ground Test Facilities(AGTF) over the whole operational envelope, a two-degree-offreedom μ synthesis method based on Line...To solve the problem of robust servo performance of Flight Environment Testbed(FET)of Altitude Ground Test Facilities(AGTF) over the whole operational envelope, a two-degree-offreedom μ synthesis method based on Linear Parameter Varying(LPV) schematic is proposed, and meanwhile a new structure frame of μ synthesis control on two degrees of freedom with double integral and weighting functions is presented, which constitutes a core support part of the paper. Aimed at the problem of reference command's rapid change, one freedom feed forward is adopted, while another freedom output feedback is used to meet good servo tracking as well as disturbance and noise rejection; furthermore, to overcome the overshoot problem and acquire dynamic tuning,the integral is introduced in inner loop, and another integral controller is used in outer loop in order to guarantee steady errors; additionally, two performance weighting functions are designed to achieve robust specialty and control energy limit considering the uncertainties in system. As the schedule parameters change over large flight envelope, the stability of closed-loop LPV system is proved using Lyapunov inequalities. The simulation results show that the relative tracking errors of temperature and pressure are less than 0.5% with LPV μ synthesis controller. Meanwhile, compared with non-LPV μ synthesis controller in large uncertainty range, the proposed approach in this research can ensure robust servo performance of FET over the whole operational envelope.展开更多
China has large population and wide territory, the natural conditions of different regions are complicated. water resources are distributed unbalanced.economic developing states are unequal. For these reasons the vari...China has large population and wide territory, the natural conditions of different regions are complicated. water resources are distributed unbalanced.economic developing states are unequal. For these reasons the variation of concerned water environment capacity has obvious character of regional differentiation. In this paper, from the economic development point of view, the regular pattern of regional differentiation of China's water environment capacity resources is analyzed. the concept of contradictory degree between water environment capacity and economic development is introduced, based on them, rivers in China are divided into three regions, and corresponding strategies to control water pollution are advanced. The aims are to use river water environment capacity resources effectively. to control pollution and to improve environmental quality.展开更多
Using newly developed methods and software, association mapping was conducted for chromium content and total sugar in tobacco leaf, based on four-omics datasets. Our objective was to collect data on genotype and pheno...Using newly developed methods and software, association mapping was conducted for chromium content and total sugar in tobacco leaf, based on four-omics datasets. Our objective was to collect data on genotype and phenotype for 60 leaf samples at four developmental stages, from three plant architectural positions and for three cultivars that were grown in two locations. Association mapping was conducted to detect genetic variants at quantitative trait SNP(QTS) loci, quantitative trait transcript(QTT) differences,quantitative trait protein(QTP) variability, and quantitative trait metabolite(QTM) changes,which can be summarized as QTX locus variation. The total heritabilities of the four-omics loci for both traits tested were 23.60% for epistasis and 15.26% for treatment interaction.Epistasis and environment × treatment interaction had important impacts on complex traits at all-omics levels. For decreasing chromium content and increasing total sugar in tobacco leaf, six methylated loci can be directly used for marker-assisted selection, and expression of ten QTTs, seven QTPs and six QTMs can be modified by selection or cultivation.展开更多
To solve the rapid transient control problem of Flight Environment Simulation System(FESS) of Altitude Ground Test Facilities(AGTF) with large heat transfer uncertainty and disturbance, a new adaptive control structur...To solve the rapid transient control problem of Flight Environment Simulation System(FESS) of Altitude Ground Test Facilities(AGTF) with large heat transfer uncertainty and disturbance, a new adaptive control structure of modified robust optimal adaptive control is presented.The mathematic modeling of FESS is given and the influence of heat transfer is analyzed through energy view. To consider the influence of heat transfer in controller design, we introduce a matched uncertainty that represents heat transfer influence in the linearized system of FESS. Based on this linear system, we deduce the design of modified robust optimal adaptive control law in a general way. Meanwhile, the robust stability of the modified robust optimal adaptive control law is proved through using Lyapunov stability theory. Then, a typical aero-engine test condition with Mach Dash and Zoom-Climb is used to verify the effectiveness of the devised adaptive controller. The simulation results show that the designed controller has servo tracking and disturbance rejection performance under heat transfer uncertainty and disturbance;the relative steady-state and dynamic errors of pressure and temperature are both smaller than 1% and 0.2% respectively. Furthermore,the influence of the modification parameter c is analyzed through simulation. Finally, comparing with the standard ideal model reference adaptive controller, the modified robust optimal adaptive controller obviously provides better control performance than the ideal model reference adaptive controller does.展开更多
Highly accurate positioning is a crucial prerequisite of multi Unmanned Aerial Vehicle close-formation flight for target tracking,formation keeping,and collision avoidance.Although the position of a UAV can be obtaine...Highly accurate positioning is a crucial prerequisite of multi Unmanned Aerial Vehicle close-formation flight for target tracking,formation keeping,and collision avoidance.Although the position of a UAV can be obtained through the Global Positioning System(GPS),it is difficult for a UAV to obtain highly accurate positioning data in a GPS-denied environment(e.g.,a GPS jamming area,suburb,urban canyon,or mountain area);this may cause it to miss a tracking target or collide with another UAV.In particular,UAV close-formation control in GPS-denied environments faces difficulties owing to the low-accuracy position,close distance between vehicles,and nonholonomic dynamics of a UAV.In this paper,on the one hand,we develop an innovative UAV formation localization method to address the formation localization issues in GPS-denied environments;on the other hand,we design a novel reinforcement learning based algorithm to achieve the high-efficiency and robust performance of the controller.First,a novel Lidar-based localization algorithm is developed to measure the localization of each aircraft in the formation flight.In our solution,each UAV is equipped with Lidar as the position measurement sensor instead of the GPS module.The k-means algorithm is implemented to calculate the center point position of UAV.A novel formation position vector matching method is proposed to match center points with UAVs in the formation and estimate their position information.Second,a reinforcement learning based UAV formation control algorithm is developed by selecting the optimal policy to control UAV swarm to start and keep flying in a close formation of a specific geometry.Third,the innovative collision risk evaluation module is proposed to address the collision-free issues in the formation group.Finally,a novel experience replay method is also provided in this paper to enhance the learning efficiency.Experimental results validate the accuracy,effectiveness,and robustness of the proposed scheme.展开更多
A large-scale high altitude environment simulation test cabin was developed to accurately control temperatures and pressures encountered at high altitudes. The system was developed to provide slope-tracking dynamic co...A large-scale high altitude environment simulation test cabin was developed to accurately control temperatures and pressures encountered at high altitudes. The system was developed to provide slope-tracking dynamic control of the temperature–pressure two-parameter and overcome the control difficulties inherent to a large inertia lag link with a complex control system which is composed of turbine refrigeration device, vacuum device and liquid nitrogen cooling device. The system includes multi-parameter decoupling of the cabin itself to avoid equipment damage of air refrigeration turbine caused by improper operation. Based on analysis of the dynamic characteristics and modeling for variations in temperature, pressure and rotation speed, an intelligent controller was implemented that includes decoupling and fuzzy arithmetic combined with an expert PID controller to control test parameters by decoupling and slope tracking control strategy. The control system employed centralized management in an open industrial ethernet architecture with an industrial computer at the core. The simulation and field debugging and running results show that this method can solve the problems of a poor anti-interference performance typical for a conventional PID and overshooting that can readily damage equipment. The steady-state characteristics meet the system requirements.展开更多
While different species in nature have safely solved the problem of navigation in a dynamic environment, this remains a challenging task for researchers around the world. The paper addresses the problem of autonomous ...While different species in nature have safely solved the problem of navigation in a dynamic environment, this remains a challenging task for researchers around the world. The paper addresses the problem of autonomous navigation in an unknown dynamic environment for a single and a group of three wheeled omnidirectional mobile robots(TWOMRs). The robot has to track a dynamic target while avoiding dynamic obstacles and dynamic walls in an unknown and very dense environment. It adopts a behavior-based controller that consists of four behaviors: "target tracking", "obstacle avoidance", "dynamic wall following" and "avoid robots". The paper considers the problem of kinematic saturation. In addition, it introduces a strategy for predicting the velocity of dynamic obstacles based on two successive measurements of the ultrasonic sensors to calculate the velocity of the obstacle expressed in the sensor frame. Furthermore, the paper proposes a strategy to deal with dynamic walls even when they have U-like or V-like shapes. The approach can also deal with the formation control of a group of robots based on the leader-follower structure and the behavior-based control, where the robots have to get together and maintain a given formation while navigating toward the target, avoiding obstacles and walls in a dynamic environment. The effectiveness of the proposed approaches is demonstrated via simulation.展开更多
To enclose the interactive relation between the underground mining with suitable protection for surface ecological environments and surface prevention of ecological environments adapting to mining disturbing was resea...To enclose the interactive relation between the underground mining with suitable protection for surface ecological environments and surface prevention of ecological environments adapting to mining disturbing was researched and developed core of this technique. There are three aspects of controlling ecological environments, to dispose and renew before exploitation, to protect surface ecological environments in the exploitative process and to repair and build up after exploitation. Based on the moving law of overburden strata in shallow seam, the surface subsidence law and the growth law of vegetation in subsidence mine area, the integrated controlling technique has been developed synthetically by methods of theoretic analysis, laboratory simulation, numerical calculation, commercial test etc.. It includes the key techniques of aquifer-protective mining, filtering and purging of mine water through goaf, preventing and extinguishing fire in shallow seam no-rock roadway layout and waste disposal in underground, frame-building ecological functional sphere before exploitation, frame-building the ecological cycle using system after mining and so on.展开更多
Autonomous vehicle technology will transform fundamentally urban traffic systems.To better enhance the coming era of connected and autonomous vehicles,effective control strategies that interact wisely with these intel...Autonomous vehicle technology will transform fundamentally urban traffic systems.To better enhance the coming era of connected and autonomous vehicles,effective control strategies that interact wisely with these intelligent vehicles for signalized at-grade intersections are indispensable.Vehicle-to-infrastructure communication technology offers unprecedented clues to reduce the delay at signalized intersections by innovative information-based control strategies.This paper proposes a new dynamic control strategy for signalized intersections with vehicle-to-signal information.The proposed strategy is called periodic vehicle holding(PVH)strategy while the traffic signal can provide information for the vehicles that are approaching an intersection.Under preliminary autonomous vehicle(PAV)environment,left-turning and through-moving vehicles will be sorted based on different information they receive.The paper shows how PVH reorganizes traffic to increase the capacity of an intersection without causing severe spillback to the upstream intersection.Results show that PVH can reduce the delay by approximately 15%at a signalized intersection under relatively high traffic demand.展开更多
On the background of analysis on region water environment safety in the Dongjiang Lake of south-central China, the source of pollution of water environment and its control are studied. The concept of region environmen...On the background of analysis on region water environment safety in the Dongjiang Lake of south-central China, the source of pollution of water environment and its control are studied. The concept of region environment disaster chain is put forward on the basis of combination study on the disaster chain theory and pollution problem in regional water environment. Through identification and analysis of pollution disaster resources in regional water environment of the Dongjiang Lake, the annual emission of the chemical oxygen demand (COD), ammonia nitrogen, total phosphorus (TP) and heavy metal (Cd, As, Pb) are counted. According to evaluation on structure proportion of contaminants in the Dongjiang Lake, agricultural non-point source is the uppermost pollution source, which accounted for 87.74% in total pollution load. Ammonia nitrogen, TP and COD are mainly contaminants accounted for 94.27% in total pollution load. By analyzing danger of contaminants in the lake, basic form of disaster chain of water environment pollution is built elementarily. It shows characteristics of branches and trunk basin disaster chain and embodies multisource disaster implication chain caused by human activities. Then, disaster resources chain-cutting methods for pollution prevention and control of regional water environment of the Dongjiang Lake are analyzed.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
Based on the analysis of current situation of water environment in the Chaohu Lake,general ideas and measures of controlling the water environment were proposed. In respect of control ideas,controlling outbreaks of bl...Based on the analysis of current situation of water environment in the Chaohu Lake,general ideas and measures of controlling the water environment were proposed. In respect of control ideas,controlling outbreaks of blue-green algae should be as one of control goals; it is needed to combine reducing the quantity of blue-green algae with decreasing eutrophication level to make the decrease in the quantity of blue-green algae larger than their natural increase until outbreaks of blue-green algae are eliminated; all kinds of techniques should be combined closely,integrated and innovated,and corresponding safeguard measures should be adopted. In respect of control measures,controlling sources of pollution and intercepting pollutants are basic measures,of which improving sewage treatment capacity and standard greatly is a key measure,and actively controlling pollution from large-scale livestock and poultry breeding is one of main measures; rivers polluted heavily should be controlled,and using microorganisms to purify small and moderate rivers can be as one of preferred techniques; blue-green algae should be dredged deeply to reducing their quantity; water should be transferred from the Yangtze River to the Chaohu Lake or the Hauihe River to purify water bodies and increase environmental capacity; reed wetland should be restored on a large scale to increase vegetation coverage from 5% to 20%; dredging should be combined with the elevation of basement of restored reed wetland.展开更多
Geological environment effects caused by the control of groundwater exploitation in Jiangyin city are discussed thoroughly, including the dynamic variation of groundwater levels and quality and the development of land...Geological environment effects caused by the control of groundwater exploitation in Jiangyin city are discussed thoroughly, including the dynamic variation of groundwater levels and quality and the development of land sub-sidence and ground fissures. According to the dynamic characteristics of groundwater levels, some advice about groundwater exploitation is offered. Our research will provide a basis for using groundwater resources and the preven- tion of geological disasters in Jiangyin city and the Suzhou-Wuxi-Changzhou area. The following results are deduced from our research. First, groundwater levels vary with the exploitation of groundwater in Jiangyin city and are affected by hydrogeological conditions. The groundwater levels remained rather stable before and after the implementation of control of groundwater exploitation in the northwest of Jiangyin city along the Yangtze River. A suitable level of exploitation should be allowed. In the southeast, the speed of recovery of the groundwater level has been rather rapid after the control of exploitation. We conclude that groundwater might be exploited locally after the groundwater level has recovered. In the southwest, the speed of recovery of the groundwater level is rather slow and exploitation of ground-water should be prohibited. Second, groundwater quality is stable in Jiangyin city and the contents of the main chemical indices of groundwater varied only slightly before and after the control of exploitation. Third, after controlling the exploitation, the speed of land subsidence has clearly slowed down and the development of ground fissures has been controlled effectively.展开更多
Development and use of controlled release fertilizer (CRF) in southern China, potential advantages of CRF in increasing rice yield and nutrient use efficiency were introduced, as well as its role of minimizing rice fi...Development and use of controlled release fertilizer (CRF) in southern China, potential advantages of CRF in increasing rice yield and nutrient use efficiency were introduced, as well as its role of minimizing rice field’s environmental contamination was discussed. Meanwhile, some suggestions were proposed.展开更多
The research objective of this review is to discuss the rationale that led to the development of Controlled Environment Agriculture (CEA) and investigate this agricultural approach as a potential solution to mitigate ...The research objective of this review is to discuss the rationale that led to the development of Controlled Environment Agriculture (CEA) and investigate this agricultural approach as a potential solution to mitigate the increased pressures on food security. It describes the need for urban cultivation systems using controlled environments and how they can be harnessed to address pressures facing food security. The factors that have contributed to the growth of CEAs, education, environmental justice, and the advantages and disadvantages of growing crops in CEAs in urban areas will be discussed. The article reviews global urban cultivation systems using controlled environments, by identifying the technologies needed to establish them. The practice of CEA is being increasingly adopted worldwide and we describe urban agriculture and compare it with traditional growing systems. Indoor farming systems that integrate into existing urban infrastructure such as vertical farming and plant factories using CEAs are discussed. Indoor farming gives urban areas enhanced access to food sources, but the cost is high, however decreasing due to recent technological advances. The current review extends the literature by incorporating recent research on the topic of agriculture in urban areas and food security. This review seeks to provide additional information regarding the viability of CEA in urban areas.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.12274019)the NSAF Joint Fund(Grant No.U2230402)。
文摘Finding the optimal control is of importance to quantum metrology under a noisy environment.In this paper,we tackle the problem of finding the optimal control to enhance the performance of quantum metrology under an arbitrary non-Markovian bosonic environment.By introducing an equivalent pseudomode model,the non-Markovian dynamic evolution is reduced to a Lindblad master equation,which helps us to calculate the gradient of quantum Fisher information and perform the gradient ascent algorithm to find the optimal control.Our approach is accurate and circumvents the need for the Born-Markovian approximation.As an example,we consider the frequency estimation of a spin with pure dephasing under two types of non-Markovian environments.By maximizing the quantum Fisher information at a fixed evolution time,we obtain the optimal multi-axis control,which results in a notable enhancement in quantum metrology.The advantage of our method lies in its applicability to the arbitrary non-Markovian bosonic environment.
文摘To effectively select risk control schemes in uncertain environments,this paper has proposed an analysis and evaluation method based on the fuzzy comprehensive evaluation method.Firstly,enterprises have adopted the brainstorming method and the Delphi method to identify risks in engineering projects,and organized the identified risks in the form of checklists to facilitate further analysis.Secondly,the fuzzy comprehensive evaluation theory was introduced to determine the comparison matrix of each risk factor and its weight.Furthermore,the top five risk factors in terms of weight ranking were taken as the evaluation factors for the selection of risk control plans.The plans were scored through the weighted scoring method,and the optimal risk control plan was determined based on the score.Finally,the feasibility of the proposed selection technology was verified through A research example of the risk control plan assessment for the construction project of Enterprise A.
文摘This paper presents a thermophysical study approach for a pure environmental control system(ECS),incorporating the geometric dimensions of heat exchangers,ram air duct,and air cycle machine(ACM)blades of the Sabreliner’s environmental control system.Real flight scenarios are simulated by considering flight input variables such as altitude,aircraft speed,compression ratio of the air cycle machine,and the mass flow rate of bleed air.The study evaluates the coefficient of performance(COP)of the environmental control system,the heat exchanger efficiencies,and the work distribution of the air cycle machine based on five flight scenarios,with a particular focus on considering the effects of humidity on environmental control system performance.The results demonstrate that at cruising altitude(11,000 m),air humidity conditions allow an increase in the COP of around 9.28%compared to dry conditions.Conversely,on land,humidity conditions reduce the performance by 4.26%compared to dry conditions.It was also found that the effects of humidity at high aircraft speeds become negligible.In general terms,the humidity conditions in the air proved to have positive effects on the environmental control system’s performance but negative effects on the heat exchanger efficiencies,reducing them by 0.22%.Additionally,land conditions reflect significant improvements in performance when the compression ratio of the air cycle machine is varied.Furthermore,in the work distribution of the air cycle machine,humidity conditions were demonstrated to consume 2.91%less work fromthe turbine compared to dry conditions.
基金co-supported by the National Natural Science Foundation of China(Nos.61773031 and 61573042)Graduate Innovation Practice Fund of Beihang University,China(No.YCSJ-01-201915)funded by the State Key Laboratory of Software Development Environment,China.
文摘In recent years,formation control of multi-agent has been a significant research subject in the field of cooperative control.However,previous works have mainly concentrated on formation control for simple point-mass model and linear model.In contrast,this paper presents a novel cooperative algorithm for multiple air vehicles formation control,which aims to devise a control strategy based on guidance route to achieve precisely coordinated formation control for a group of fixed-wing aircraft in a complex task environment.The proposed method introduces the leader-follower structure for effective organization of the multi-agent coordination.Moreover,the Partial Integrated Formation and Control(PIFC)is adopted to design the control law for Guidance-Route based Formation Control(GRFC).Additionally,the proposed approach designs two guidance-route generation strategies for two special situations to demonstrate the effectiveness of GRFC in complex task environments.Theoretical analysis reveals that the proposed control protocol for guidance command can ensure the overall stability and tracking accuracy of the system.Numerical simulations are performed to illustrate the theoretical results,and verify that the proposed approach can achieve coordinated formation control precisely in a complex task environment.
文摘To solve the problem of robust servo performance of Flight Environment Testbed(FET)of Altitude Ground Test Facilities(AGTF) over the whole operational envelope, a two-degree-offreedom μ synthesis method based on Linear Parameter Varying(LPV) schematic is proposed, and meanwhile a new structure frame of μ synthesis control on two degrees of freedom with double integral and weighting functions is presented, which constitutes a core support part of the paper. Aimed at the problem of reference command's rapid change, one freedom feed forward is adopted, while another freedom output feedback is used to meet good servo tracking as well as disturbance and noise rejection; furthermore, to overcome the overshoot problem and acquire dynamic tuning,the integral is introduced in inner loop, and another integral controller is used in outer loop in order to guarantee steady errors; additionally, two performance weighting functions are designed to achieve robust specialty and control energy limit considering the uncertainties in system. As the schedule parameters change over large flight envelope, the stability of closed-loop LPV system is proved using Lyapunov inequalities. The simulation results show that the relative tracking errors of temperature and pressure are less than 0.5% with LPV μ synthesis controller. Meanwhile, compared with non-LPV μ synthesis controller in large uncertainty range, the proposed approach in this research can ensure robust servo performance of FET over the whole operational envelope.
文摘China has large population and wide territory, the natural conditions of different regions are complicated. water resources are distributed unbalanced.economic developing states are unequal. For these reasons the variation of concerned water environment capacity has obvious character of regional differentiation. In this paper, from the economic development point of view, the regular pattern of regional differentiation of China's water environment capacity resources is analyzed. the concept of contradictory degree between water environment capacity and economic development is introduced, based on them, rivers in China are divided into three regions, and corresponding strategies to control water pollution are advanced. The aims are to use river water environment capacity resources effectively. to control pollution and to improve environmental quality.
基金supported by the National Basic Research Program of China (2011CB109306 and 2009CB118404)the Program of Introducing Talents of Discipline to Universities of China ("111" Project, B06014)Research Programs (CNTC-D2011100, CNTC-[2012]146, NY-[2011]3047, QKHRZ [2013] 02)
文摘Using newly developed methods and software, association mapping was conducted for chromium content and total sugar in tobacco leaf, based on four-omics datasets. Our objective was to collect data on genotype and phenotype for 60 leaf samples at four developmental stages, from three plant architectural positions and for three cultivars that were grown in two locations. Association mapping was conducted to detect genetic variants at quantitative trait SNP(QTS) loci, quantitative trait transcript(QTT) differences,quantitative trait protein(QTP) variability, and quantitative trait metabolite(QTM) changes,which can be summarized as QTX locus variation. The total heritabilities of the four-omics loci for both traits tested were 23.60% for epistasis and 15.26% for treatment interaction.Epistasis and environment × treatment interaction had important impacts on complex traits at all-omics levels. For decreasing chromium content and increasing total sugar in tobacco leaf, six methylated loci can be directly used for marker-assisted selection, and expression of ten QTTs, seven QTPs and six QTMs can be modified by selection or cultivation.
基金funded by China Scholarship Council (CSC)and National Science and Technology Major Project,China(No. 2017-V-0015-0067)。
文摘To solve the rapid transient control problem of Flight Environment Simulation System(FESS) of Altitude Ground Test Facilities(AGTF) with large heat transfer uncertainty and disturbance, a new adaptive control structure of modified robust optimal adaptive control is presented.The mathematic modeling of FESS is given and the influence of heat transfer is analyzed through energy view. To consider the influence of heat transfer in controller design, we introduce a matched uncertainty that represents heat transfer influence in the linearized system of FESS. Based on this linear system, we deduce the design of modified robust optimal adaptive control law in a general way. Meanwhile, the robust stability of the modified robust optimal adaptive control law is proved through using Lyapunov stability theory. Then, a typical aero-engine test condition with Mach Dash and Zoom-Climb is used to verify the effectiveness of the devised adaptive controller. The simulation results show that the designed controller has servo tracking and disturbance rejection performance under heat transfer uncertainty and disturbance;the relative steady-state and dynamic errors of pressure and temperature are both smaller than 1% and 0.2% respectively. Furthermore,the influence of the modification parameter c is analyzed through simulation. Finally, comparing with the standard ideal model reference adaptive controller, the modified robust optimal adaptive controller obviously provides better control performance than the ideal model reference adaptive controller does.
基金This work was co-funded by the National Natural Science Foundation of China(No.52072309)Key Research and Development Program of Shaanxi,China(No.2019ZDLGY14-02-01)+5 种基金Shenzhen Fundamental Research Program,China(No.JCYJ20190806152203506)Aeronautical Science Foundation of China(No.ASFC-2018ZC53026)Funding Project with Beijing Institute of Spacecraft System Engineering,China(No.JSZL2020203B004)the Basic Research Program of Taicang,China(No.TC2021JC09)the Natural Science Foundation of Shaanxi Province,China(No.2023-JC-QN-0003)Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University,China(No.CX2021033).
文摘Highly accurate positioning is a crucial prerequisite of multi Unmanned Aerial Vehicle close-formation flight for target tracking,formation keeping,and collision avoidance.Although the position of a UAV can be obtained through the Global Positioning System(GPS),it is difficult for a UAV to obtain highly accurate positioning data in a GPS-denied environment(e.g.,a GPS jamming area,suburb,urban canyon,or mountain area);this may cause it to miss a tracking target or collide with another UAV.In particular,UAV close-formation control in GPS-denied environments faces difficulties owing to the low-accuracy position,close distance between vehicles,and nonholonomic dynamics of a UAV.In this paper,on the one hand,we develop an innovative UAV formation localization method to address the formation localization issues in GPS-denied environments;on the other hand,we design a novel reinforcement learning based algorithm to achieve the high-efficiency and robust performance of the controller.First,a novel Lidar-based localization algorithm is developed to measure the localization of each aircraft in the formation flight.In our solution,each UAV is equipped with Lidar as the position measurement sensor instead of the GPS module.The k-means algorithm is implemented to calculate the center point position of UAV.A novel formation position vector matching method is proposed to match center points with UAVs in the formation and estimate their position information.Second,a reinforcement learning based UAV formation control algorithm is developed by selecting the optimal policy to control UAV swarm to start and keep flying in a close formation of a specific geometry.Third,the innovative collision risk evaluation module is proposed to address the collision-free issues in the formation group.Finally,a novel experience replay method is also provided in this paper to enhance the learning efficiency.Experimental results validate the accuracy,effectiveness,and robustness of the proposed scheme.
基金supported by the Aeronautical Science Foun-dation of China(No.2012XX51043)‘‘Fanzhou’’Youth Scientific Funds of China(No.20100504)
文摘A large-scale high altitude environment simulation test cabin was developed to accurately control temperatures and pressures encountered at high altitudes. The system was developed to provide slope-tracking dynamic control of the temperature–pressure two-parameter and overcome the control difficulties inherent to a large inertia lag link with a complex control system which is composed of turbine refrigeration device, vacuum device and liquid nitrogen cooling device. The system includes multi-parameter decoupling of the cabin itself to avoid equipment damage of air refrigeration turbine caused by improper operation. Based on analysis of the dynamic characteristics and modeling for variations in temperature, pressure and rotation speed, an intelligent controller was implemented that includes decoupling and fuzzy arithmetic combined with an expert PID controller to control test parameters by decoupling and slope tracking control strategy. The control system employed centralized management in an open industrial ethernet architecture with an industrial computer at the core. The simulation and field debugging and running results show that this method can solve the problems of a poor anti-interference performance typical for a conventional PID and overshooting that can readily damage equipment. The steady-state characteristics meet the system requirements.
文摘While different species in nature have safely solved the problem of navigation in a dynamic environment, this remains a challenging task for researchers around the world. The paper addresses the problem of autonomous navigation in an unknown dynamic environment for a single and a group of three wheeled omnidirectional mobile robots(TWOMRs). The robot has to track a dynamic target while avoiding dynamic obstacles and dynamic walls in an unknown and very dense environment. It adopts a behavior-based controller that consists of four behaviors: "target tracking", "obstacle avoidance", "dynamic wall following" and "avoid robots". The paper considers the problem of kinematic saturation. In addition, it introduces a strategy for predicting the velocity of dynamic obstacles based on two successive measurements of the ultrasonic sensors to calculate the velocity of the obstacle expressed in the sensor frame. Furthermore, the paper proposes a strategy to deal with dynamic walls even when they have U-like or V-like shapes. The approach can also deal with the formation control of a group of robots based on the leader-follower structure and the behavior-based control, where the robots have to get together and maintain a given formation while navigating toward the target, avoiding obstacles and walls in a dynamic environment. The effectiveness of the proposed approaches is demonstrated via simulation.
文摘To enclose the interactive relation between the underground mining with suitable protection for surface ecological environments and surface prevention of ecological environments adapting to mining disturbing was researched and developed core of this technique. There are three aspects of controlling ecological environments, to dispose and renew before exploitation, to protect surface ecological environments in the exploitative process and to repair and build up after exploitation. Based on the moving law of overburden strata in shallow seam, the surface subsidence law and the growth law of vegetation in subsidence mine area, the integrated controlling technique has been developed synthetically by methods of theoretic analysis, laboratory simulation, numerical calculation, commercial test etc.. It includes the key techniques of aquifer-protective mining, filtering and purging of mine water through goaf, preventing and extinguishing fire in shallow seam no-rock roadway layout and waste disposal in underground, frame-building ecological functional sphere before exploitation, frame-building the ecological cycle using system after mining and so on.
文摘Autonomous vehicle technology will transform fundamentally urban traffic systems.To better enhance the coming era of connected and autonomous vehicles,effective control strategies that interact wisely with these intelligent vehicles for signalized at-grade intersections are indispensable.Vehicle-to-infrastructure communication technology offers unprecedented clues to reduce the delay at signalized intersections by innovative information-based control strategies.This paper proposes a new dynamic control strategy for signalized intersections with vehicle-to-signal information.The proposed strategy is called periodic vehicle holding(PVH)strategy while the traffic signal can provide information for the vehicles that are approaching an intersection.Under preliminary autonomous vehicle(PAV)environment,left-turning and through-moving vehicles will be sorted based on different information they receive.The paper shows how PVH reorganizes traffic to increase the capacity of an intersection without causing severe spillback to the upstream intersection.Results show that PVH can reduce the delay by approximately 15%at a signalized intersection under relatively high traffic demand.
文摘On the background of analysis on region water environment safety in the Dongjiang Lake of south-central China, the source of pollution of water environment and its control are studied. The concept of region environment disaster chain is put forward on the basis of combination study on the disaster chain theory and pollution problem in regional water environment. Through identification and analysis of pollution disaster resources in regional water environment of the Dongjiang Lake, the annual emission of the chemical oxygen demand (COD), ammonia nitrogen, total phosphorus (TP) and heavy metal (Cd, As, Pb) are counted. According to evaluation on structure proportion of contaminants in the Dongjiang Lake, agricultural non-point source is the uppermost pollution source, which accounted for 87.74% in total pollution load. Ammonia nitrogen, TP and COD are mainly contaminants accounted for 94.27% in total pollution load. By analyzing danger of contaminants in the lake, basic form of disaster chain of water environment pollution is built elementarily. It shows characteristics of branches and trunk basin disaster chain and embodies multisource disaster implication chain caused by human activities. Then, disaster resources chain-cutting methods for pollution prevention and control of regional water environment of the Dongjiang Lake are analyzed.
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.
文摘Based on the analysis of current situation of water environment in the Chaohu Lake,general ideas and measures of controlling the water environment were proposed. In respect of control ideas,controlling outbreaks of blue-green algae should be as one of control goals; it is needed to combine reducing the quantity of blue-green algae with decreasing eutrophication level to make the decrease in the quantity of blue-green algae larger than their natural increase until outbreaks of blue-green algae are eliminated; all kinds of techniques should be combined closely,integrated and innovated,and corresponding safeguard measures should be adopted. In respect of control measures,controlling sources of pollution and intercepting pollutants are basic measures,of which improving sewage treatment capacity and standard greatly is a key measure,and actively controlling pollution from large-scale livestock and poultry breeding is one of main measures; rivers polluted heavily should be controlled,and using microorganisms to purify small and moderate rivers can be as one of preferred techniques; blue-green algae should be dredged deeply to reducing their quantity; water should be transferred from the Yangtze River to the Chaohu Lake or the Hauihe River to purify water bodies and increase environmental capacity; reed wetland should be restored on a large scale to increase vegetation coverage from 5% to 20%; dredging should be combined with the elevation of basement of restored reed wetland.
基金Projects 2002CB412702 supported by the Special Funds for Major State Basic Research Projects of China and KZCX2-YW-113the Special Funds ofResearch Innovation Projects of CAS
文摘Geological environment effects caused by the control of groundwater exploitation in Jiangyin city are discussed thoroughly, including the dynamic variation of groundwater levels and quality and the development of land sub-sidence and ground fissures. According to the dynamic characteristics of groundwater levels, some advice about groundwater exploitation is offered. Our research will provide a basis for using groundwater resources and the preven- tion of geological disasters in Jiangyin city and the Suzhou-Wuxi-Changzhou area. The following results are deduced from our research. First, groundwater levels vary with the exploitation of groundwater in Jiangyin city and are affected by hydrogeological conditions. The groundwater levels remained rather stable before and after the implementation of control of groundwater exploitation in the northwest of Jiangyin city along the Yangtze River. A suitable level of exploitation should be allowed. In the southeast, the speed of recovery of the groundwater level has been rather rapid after the control of exploitation. We conclude that groundwater might be exploited locally after the groundwater level has recovered. In the southwest, the speed of recovery of the groundwater level is rather slow and exploitation of ground-water should be prohibited. Second, groundwater quality is stable in Jiangyin city and the contents of the main chemical indices of groundwater varied only slightly before and after the control of exploitation. Third, after controlling the exploitation, the speed of land subsidence has clearly slowed down and the development of ground fissures has been controlled effectively.
基金This study was supported by National Natural Science Foundation of China (30270770) Foundation for Achievement Transfer (02EFN214301156) and PPI/PPIC-China Cooperation Project (HN-13).
文摘Development and use of controlled release fertilizer (CRF) in southern China, potential advantages of CRF in increasing rice yield and nutrient use efficiency were introduced, as well as its role of minimizing rice field’s environmental contamination was discussed. Meanwhile, some suggestions were proposed.
文摘The research objective of this review is to discuss the rationale that led to the development of Controlled Environment Agriculture (CEA) and investigate this agricultural approach as a potential solution to mitigate the increased pressures on food security. It describes the need for urban cultivation systems using controlled environments and how they can be harnessed to address pressures facing food security. The factors that have contributed to the growth of CEAs, education, environmental justice, and the advantages and disadvantages of growing crops in CEAs in urban areas will be discussed. The article reviews global urban cultivation systems using controlled environments, by identifying the technologies needed to establish them. The practice of CEA is being increasingly adopted worldwide and we describe urban agriculture and compare it with traditional growing systems. Indoor farming systems that integrate into existing urban infrastructure such as vertical farming and plant factories using CEAs are discussed. Indoor farming gives urban areas enhanced access to food sources, but the cost is high, however decreasing due to recent technological advances. The current review extends the literature by incorporating recent research on the topic of agriculture in urban areas and food security. This review seeks to provide additional information regarding the viability of CEA in urban areas.
