Building energy consumption accounts for nearly 40% of global energy consumption, HVAC （Heating, Ventilating, and Air Conditioning） systems are the major building energy consumers, and as one type of HVAC systems, t...Building energy consumption accounts for nearly 40% of global energy consumption, HVAC （Heating, Ventilating, and Air Conditioning） systems are the major building energy consumers, and as one type of HVAC systems, the heat pump air conditioning system, which is more energy-efficient compared to the traditional air conditioning system, is being more widely used to save energy. However, in northern China, extreme climatic conditions increase the cooling and heating load of the heat pump air conditioning system and accelerate the aging of the equipment, and the sensor may detect drifted parameters owing to climate change. This non-linear drifted parameter increases the false alarm rate of the fault detection and the need for unnecessary troubleshooting. In order to overcome the impact of the device aging and the drifted parameter, a Kalman filter and SPC （statistical process control） fault detection method are introduced in this paper. In this method, the model parameter and its standard variance can he estimated by Kalman filter based on the gray model and the real-time data of the air conditioning system. Further, by using SPC to construct the dynamic control limits, false alarm rate is reduced. And this paper mainly focuses on the cold machine failure in the component failure and its soft fault detection. This approach has been tested on a simulation model of the ＂Sino-German Energy Conservation Demonstration Center＂ building heat pump air-conditioning system in Shenyang, China, and the results show that the Kalman filter and SPC fault detection method is simple and highly efficient with a low false alarm rate, and it can deal with the difficulties caused by the extreme environment and the non-linear influence of the parameters, and what＇s more, it provides a good foundation for dynamic fault diagnosis and fault prediction analysis.展开更多
Initiated three decades ago,integrated design of controllers and fault detectors has continuously attracted research attention.The recent development of the unified control and detection framework with an observer-bas...Initiated three decades ago,integrated design of controllers and fault detectors has continuously attracted research attention.The recent development of the unified control and detection framework with an observer-based residual generator in its core gives a more general form of the previous works.Its applications to residual centred modelling of uncertain control systems,fault detection in feedback control systems with uncertainties,fault-tolerant control(FTC)as well as control performance degradation monitoring,detection and recovery are introduced.In conclusion,some future perspectives are proposed.展开更多
Understanding the dynamics of surface water area and their drivers is crucial for human survival and ecosystem stability in inland arid and semi-arid areas.This study took Gansu Province,China,a typical area with comp...Understanding the dynamics of surface water area and their drivers is crucial for human survival and ecosystem stability in inland arid and semi-arid areas.This study took Gansu Province,China,a typical area with complex terrain and variable climate,as the research subject.Based on Google Earth Engine,we used Landsat data and the Open-surface Water Detection Method with Enhanced Impurity Control method to monitor the spatiotemporal dynamics of surface water area in Gansu Province from 1985 to 2022,and quantitatively analyzed the main causes of regional differences in surface water area.The findings revealed that surface water area in Gansu Province expanded by 406.88 km2 from 1985 to 2022.Seasonal surface water area exhibited significant fluctuations,while permanent surface water area showed a steady increase.Notably,terrestrial water storage exhibited a trend of first decreasing and then increasing,correlated with the dynamics of surface water area.Climate change and human activities jointly affected surface hydrological processes,with the impact of climate change being slightly higher than that of human activities.Spatially,climate change affected the'source'of surface water to a greater extent,while human activities tended to affect the'destination'of surface water.Challenges of surface water resources faced by inland arid and semi-arid areas like Gansu Province are multifaceted.Therefore,we summarized the surface hydrology patterns typical in inland arid and semi-arid areas and tailored surface water'supply-demand'balance strategies.The study not only sheds light on the dynamics of surface water area in Gansu Province,but also offers valuable insights for ecological protection and surface water resource management in inland arid and semi-arid areas facing water scarcity.展开更多
The real-time transient stability detection and emergency control technology based on wide area response has become a hot research area in power system stability studies.Several different technologies have been propos...The real-time transient stability detection and emergency control technology based on wide area response has become a hot research area in power system stability studies.Several different technologies have been proposed,but lots of problems remain to be solved before they can be applied in practice.A wide area measurement system(WAMS)based test platform is developed for transient stability detection and control.The design as well as main function modules of the platform are introduced.In addition,three generator power angle prediction methods and six response based transient instability detection technologies are given.Results of engineering application demonstrate that the developed test platform can provide a real-time operation environment,which can effectively compare and analyze the validity and practicability of these transient stability detection technologies.Based on the measured perturbed trajectories from actual power systems or the Real-Time Digital Simulators(RTDS),the platform can realize the assessment and visual result presentation of various responses from different transient instability detection technologies.The test platform can be applied to different power systems and it is convenient to embed new transient instability detection modules.Meanwhile some deficiencies and shortcomings in engineering application are pointed out and corresponding suggestions are given.In conclusion,the hardware and software structure,function modulus and engineering applications are presented.The application in actual power systems shows that it has a good application perspective.展开更多
This note addresses diagnosis and performance degradation detection issues from an integrated viewpoint of functionality maintenance and cyber security of automatic control systems.It calls for more research attention...This note addresses diagnosis and performance degradation detection issues from an integrated viewpoint of functionality maintenance and cyber security of automatic control systems.It calls for more research attention on three aspects:(i)application of control and detection uni ed framework to enhancing the diagnosis capability of feedback control systems,(ii)projection-based fault detection,and complementary and explainable applications of projection-and machine learning-based techniques,and(iii)system performance degradation detection that is of elemental importance for today's automatic control systems.Some ideas and conceptual schemes are presented and illustrated by means of examples,serving as convincing arguments for research e orts in these aspects.They would contribute to the future development of capable diagnosis systems for functionality safe and cyber secure automatic control systems.展开更多
We demonstrate an ultralow-noise single-photon detection system based on a sensitive photomultiplier tube（PMT） with precise temperature control, which can capture fast single photons with intervals around 10 ns.By i...We demonstrate an ultralow-noise single-photon detection system based on a sensitive photomultiplier tube（PMT） with precise temperature control, which can capture fast single photons with intervals around 10 ns.By improvement of the electromagnetic shielding and introduction of the self-differencing method, the dark counts（DCs） are cut down to ~1%. We further develop an ultra-stable PMT cooling subsystem and observe that the DC goes down by a factor of 3.9 each time the temperature drops 10°C. At -20°C it is reduced 400 times with respect to the room temperature（25°C）, that is, it becomes only 2 counts per second, which is on par with the superconducting nanowire detectors. Meanwhile, despite a 50% loss, the detection efficiency is still 13%. Our detector is available for ultra-precise single-photon detection in environments with strong electromagnetic disturbances.展开更多
A novel controlled laser air-force detection(CLAFD)technique was developed to detect the rheological properties of polymers with the characteristics of non-destruction and cross-contamination free.Dynamic testing and ...A novel controlled laser air-force detection(CLAFD)technique was developed to detect the rheological properties of polymers with the characteristics of non-destruction and cross-contamination free.Dynamic testing and static testing were carried out in the technique.Back propagation neural network algorithm was used to establish the air-force control model.The replicability of CLAFD system was analyzed,the viscoelastic properties of polyurethane were investigated using alternating load testing.A comparative analysis of performances was made between the CLAFD and the texture analysis(TA)on the testing of creep-recovery and stress relaxation.The results demonstrated that the CLAFD system had good replicability.The lagging phase angle was between 0°-90°in the testing of alternating load.This illustrated that the CLAFD technique could be used to detect viscoelasticity.The parameters of response speed and the precision of the CLAFD entirely surpassed the TA on the creep-recovery testing.The CLAFD technique will provide a new real-time,non-destruction and cross-contamination-free detection method for material science,especially for those materials such as artificial biological tissue and function food products.展开更多
基金Supported by the National Natural Science Foundation Committee of China(61503259)China Postdoctoral Science Foundation Funded Project(2017M611261)+1 种基金Chinese Scholarship Council(201608210107)Hanyu Plan of Shenyang Jianzhu University(XKHY2-64)
文摘Building energy consumption accounts for nearly 40% of global energy consumption, HVAC （Heating, Ventilating, and Air Conditioning） systems are the major building energy consumers, and as one type of HVAC systems, the heat pump air conditioning system, which is more energy-efficient compared to the traditional air conditioning system, is being more widely used to save energy. However, in northern China, extreme climatic conditions increase the cooling and heating load of the heat pump air conditioning system and accelerate the aging of the equipment, and the sensor may detect drifted parameters owing to climate change. This non-linear drifted parameter increases the false alarm rate of the fault detection and the need for unnecessary troubleshooting. In order to overcome the impact of the device aging and the drifted parameter, a Kalman filter and SPC （statistical process control） fault detection method are introduced in this paper. In this method, the model parameter and its standard variance can he estimated by Kalman filter based on the gray model and the real-time data of the air conditioning system. Further, by using SPC to construct the dynamic control limits, false alarm rate is reduced. And this paper mainly focuses on the cold machine failure in the component failure and its soft fault detection. This approach has been tested on a simulation model of the ＂Sino-German Energy Conservation Demonstration Center＂ building heat pump air-conditioning system in Shenyang, China, and the results show that the Kalman filter and SPC fault detection method is simple and highly efficient with a low false alarm rate, and it can deal with the difficulties caused by the extreme environment and the non-linear influence of the parameters, and what＇s more, it provides a good foundation for dynamic fault diagnosis and fault prediction analysis.
基金This work was supported by the National Natural Science Foundation of China(62020106003,62073029)the Beijing Natural Science Foundation(4202045)the Fundamental Research Funds for the Central Universities(FRF-TP-20-012A3).
文摘Initiated three decades ago,integrated design of controllers and fault detectors has continuously attracted research attention.The recent development of the unified control and detection framework with an observer-based residual generator in its core gives a more general form of the previous works.Its applications to residual centred modelling of uncertain control systems,fault detection in feedback control systems with uncertainties,fault-tolerant control(FTC)as well as control performance degradation monitoring,detection and recovery are introduced.In conclusion,some future perspectives are proposed.
基金This research was supported by the Third Xinjiang Scientific Expedition Program(2021xjkk010102)the National Natural Science Foundation of China(41261047,41761043)+1 种基金the Science and Technology Plan of Gansu Province,China(20YF3FA042)the Youth Teacher Scientific Capability Promoting Project of Northwest Normal University,Gansu Province,China(NWNU-LKQN-17-7).
文摘Understanding the dynamics of surface water area and their drivers is crucial for human survival and ecosystem stability in inland arid and semi-arid areas.This study took Gansu Province,China,a typical area with complex terrain and variable climate,as the research subject.Based on Google Earth Engine,we used Landsat data and the Open-surface Water Detection Method with Enhanced Impurity Control method to monitor the spatiotemporal dynamics of surface water area in Gansu Province from 1985 to 2022,and quantitatively analyzed the main causes of regional differences in surface water area.The findings revealed that surface water area in Gansu Province expanded by 406.88 km2 from 1985 to 2022.Seasonal surface water area exhibited significant fluctuations,while permanent surface water area showed a steady increase.Notably,terrestrial water storage exhibited a trend of first decreasing and then increasing,correlated with the dynamics of surface water area.Climate change and human activities jointly affected surface hydrological processes,with the impact of climate change being slightly higher than that of human activities.Spatially,climate change affected the'source'of surface water to a greater extent,while human activities tended to affect the'destination'of surface water.Challenges of surface water resources faced by inland arid and semi-arid areas like Gansu Province are multifaceted.Therefore,we summarized the surface hydrology patterns typical in inland arid and semi-arid areas and tailored surface water'supply-demand'balance strategies.The study not only sheds light on the dynamics of surface water area in Gansu Province,but also offers valuable insights for ecological protection and surface water resource management in inland arid and semi-arid areas facing water scarcity.
基金Supported by National Natural Science Foundation of China(51577049)Open Foundation of State Key Lab.of Alternate Electrical Power System with Renewable Energy Sources(Grant No.LAPS14005).
文摘The real-time transient stability detection and emergency control technology based on wide area response has become a hot research area in power system stability studies.Several different technologies have been proposed,but lots of problems remain to be solved before they can be applied in practice.A wide area measurement system(WAMS)based test platform is developed for transient stability detection and control.The design as well as main function modules of the platform are introduced.In addition,three generator power angle prediction methods and six response based transient instability detection technologies are given.Results of engineering application demonstrate that the developed test platform can provide a real-time operation environment,which can effectively compare and analyze the validity and practicability of these transient stability detection technologies.Based on the measured perturbed trajectories from actual power systems or the Real-Time Digital Simulators(RTDS),the platform can realize the assessment and visual result presentation of various responses from different transient instability detection technologies.The test platform can be applied to different power systems and it is convenient to embed new transient instability detection modules.Meanwhile some deficiencies and shortcomings in engineering application are pointed out and corresponding suggestions are given.In conclusion,the hardware and software structure,function modulus and engineering applications are presented.The application in actual power systems shows that it has a good application perspective.
文摘This note addresses diagnosis and performance degradation detection issues from an integrated viewpoint of functionality maintenance and cyber security of automatic control systems.It calls for more research attention on three aspects:(i)application of control and detection uni ed framework to enhancing the diagnosis capability of feedback control systems,(ii)projection-based fault detection,and complementary and explainable applications of projection-and machine learning-based techniques,and(iii)system performance degradation detection that is of elemental importance for today's automatic control systems.Some ideas and conceptual schemes are presented and illustrated by means of examples,serving as convincing arguments for research e orts in these aspects.They would contribute to the future development of capable diagnosis systems for functionality safe and cyber secure automatic control systems.
基金supported by the National Natural Science Foundation of China(Nos.11574026 and 11274037)the Program for New Century Excellent Talents in University,MOE of China(No.NCET-12-0765)the Foundation for the Author of National Excellent Doctoral Dissertation,China(No.201236)
文摘We demonstrate an ultralow-noise single-photon detection system based on a sensitive photomultiplier tube（PMT） with precise temperature control, which can capture fast single photons with intervals around 10 ns.By improvement of the electromagnetic shielding and introduction of the self-differencing method, the dark counts（DCs） are cut down to ~1%. We further develop an ultra-stable PMT cooling subsystem and observe that the DC goes down by a factor of 3.9 each time the temperature drops 10°C. At -20°C it is reduced 400 times with respect to the room temperature（25°C）, that is, it becomes only 2 counts per second, which is on par with the superconducting nanowire detectors. Meanwhile, despite a 50% loss, the detection efficiency is still 13%. Our detector is available for ultra-precise single-photon detection in environments with strong electromagnetic disturbances.
基金the National Natural Science Foundation Project of the People’s Republic of China(Grant No.31571921)the National Science Foundation Project of the United States of America(Grant No.8018)the Beijing Natural Science Foundation of the People’s Republic of China(Grant No.6202020).
文摘A novel controlled laser air-force detection(CLAFD)technique was developed to detect the rheological properties of polymers with the characteristics of non-destruction and cross-contamination free.Dynamic testing and static testing were carried out in the technique.Back propagation neural network algorithm was used to establish the air-force control model.The replicability of CLAFD system was analyzed,the viscoelastic properties of polyurethane were investigated using alternating load testing.A comparative analysis of performances was made between the CLAFD and the texture analysis(TA)on the testing of creep-recovery and stress relaxation.The results demonstrated that the CLAFD system had good replicability.The lagging phase angle was between 0°-90°in the testing of alternating load.This illustrated that the CLAFD technique could be used to detect viscoelasticity.The parameters of response speed and the precision of the CLAFD entirely surpassed the TA on the creep-recovery testing.The CLAFD technique will provide a new real-time,non-destruction and cross-contamination-free detection method for material science,especially for those materials such as artificial biological tissue and function food products.
