Aiming at the problem that the traditional Unscented Kalman Filtering(UKF) algorithm can't solve the problem that the measurement covariance matrix is unknown and the measured value contains outliers,this paper pr...Aiming at the problem that the traditional Unscented Kalman Filtering(UKF) algorithm can't solve the problem that the measurement covariance matrix is unknown and the measured value contains outliers,this paper proposes a robust adaptive UKF algorithm based on Support Vector Regression(SVR).The algorithm combines the advantages of support vector regression with small samples,nonlinear learning ability and online estimation capability of adaptive algorithm based on innovation.Firstly,the SVR model is trained by using the innovation in the sliding window,and the new innovation is monitored.If the deviation between the estimated innovation and the measured innovation exceeds a given threshold,then measured innovation will be replaced by the predicted innovation,and then the processed innovation is used to calculate the measurement noise covariance matrix using the adaptive estimation algorithm.Simulation experiments and measured data experiments show that SVRUKF is significantly better than the traditional UKF,robust UKF and adaptive UKF algorithms for the case where the covariance matrix is unknown and the measured values have outliers.展开更多
Solar arrays are important and indispensable parts of spacecraft and provide energy support for spacecraft to operate in orbit and complete on-orbit missions.When a spacecraft is in orbit,because the solar array is ex...Solar arrays are important and indispensable parts of spacecraft and provide energy support for spacecraft to operate in orbit and complete on-orbit missions.When a spacecraft is in orbit,because the solar array is exposed to the harsh space environment,with increasing working time,the performance of its internal electronic components gradually degrade until abnormal damage occurs.This damage makes solar array power generation unable to fully meet the energy demand of a spacecraft.Therefore,timely and accurate detection of solar array anomalies is of great significance for the on-orbit operation and maintenance management of spacecraft.In this paper,we propose an anomaly detection method for spacecraft solar arrays based on the integrated least squares support vector machine(ILS-SVM)model:it selects correlated telemetry data from spacecraft solar arrays to form a training set and extracts n groups of training subsets from this set,then gets n corresponding least squares support vector machine(LS-SVM)submodels by training on these training subsets,respectively;after that,the ILS-SVM model is obtained by integrating these submodels through a weighting operation to increase the prediction accuracy and so on;finally,based on the obtained ILS-SVM model,a parameterfree and unsupervised anomaly determination method is proposed to detect the health status of solar arrays.We use the telemetry data set from a satellite in orbit to carry out experimental verification and find that the proposed method can diagnose solar array anomalies in time and can capture the signs before a solar array anomaly occurs,which reflects the applicability of the method.展开更多
In view of the problem that the current single-antenna GPS attitude determination system can only determine the body attitude when the sideslip angle is zero and the multiantenna GPS/SINS integrated navigation system ...In view of the problem that the current single-antenna GPS attitude determination system can only determine the body attitude when the sideslip angle is zero and the multiantenna GPS/SINS integrated navigation system is of large volume, high cost, and complex structure, this approach is presented to determine the attitude based on vector space with single-antenna GPS and accelerometers in the micro inertial measurement unit （MIMU）. It can provide real-time and accurate attitude information. Subsequently, the single-antenna GPS/SINS integrated navigation system is designed based on the combination of position, velocity, and attitude. Finally the semi- physical simulations of single-antenna GPS attitude determination system and single-antenna GPS/SINS integrated navigation system are carried out. The simulation results, based on measured data, show that the single-antenna GPS/SINS system can provide more accurate navigation information compared to the GPS/SINS system, based on the combination of position and velocity. Furthermore, the single-antenna GPS/SINS system is characteristic of lower cost and simpler structure. It provides the basis for the application of a single-antenna GPS/SINS integrated navigation system in a micro aerial vehicle （MAV）.展开更多
Herein,we propose a novel three-phase quasi-Z-source inverter with a high voltage transmission ratio to address challenges such as high switching loss and sizeable magnetic components in the basic quasi-Z-source inver...Herein,we propose a novel three-phase quasi-Z-source inverter with a high voltage transmission ratio to address challenges such as high switching loss and sizeable magnetic components in the basic quasi-Z-source inverter.The proposed circuit topology,control strategy,and related analysis are presented.The circuit topology of the inverter comprises a quasi-Z-source network with an integrated magnetic inductor,an active clamp circuit,a three-phase inverter bridge,and an output LC filter,all of which are connected in series.An improved 12-sector space vector modulation scheme is proposed based on the root-mean-square value of the voltage and the instantaneous value of the current.Furthermore,analyses of the inverter voltage transmission ratio,resonant process,and parametric design guidelines for integrated magnetic inductor and zero-voltage switching conditions are presented.Experimental results on a 1-kVA prototype inverter demonstrate that the proposed inverter exhibits a higher transmission ratio and efficiency than existing inverters;thus,the proposed inverter would have broad prospects in low-voltage DC-AC applications.展开更多
Background:The control of vector-borne diseases(VBD)is one of the greatest challenges on the global health agenda.Rapid and uncontrolled urbanization has heightened the interest in addressing these challenges through ...Background:The control of vector-borne diseases(VBD)is one of the greatest challenges on the global health agenda.Rapid and uncontrolled urbanization has heightened the interest in addressing these challenges through an integrated vector management(IVM)approach.The aim was to identify components related to impacts,economic evaluation,and sustainability that might contribute to this integrated approach to VBD prevention.Main body:We conducted a scoping review of available literature(2000-2016)using PubMed,Web of Science,Cochrane,CINAHL,Econlit,LILACS,Global Health Database,Scopus,and Embase,as well as Tropical Diseases Bulletin,WHOLIS,WHO Pesticide Evaluation Scheme,and Google Scholar.MeSH terms and free-text terms were used.A data extraction form was used,including TIDieR and ASTAIRE.MMAT and CHEERS were used to evaluate quality.Of the 42 documents reviewed,30 were focused on dengue,eight on malaria,and two on leishmaniasis.More than a half of the studies were conducted in the Americas.Half used a quantitative descriptive approach(n=21),followed by cluster randomized controlled trials(n=11).Regarding impacts,outcomes were:a)use of measures for vector control;b)vector control;c)health measures;and d)social measures.IVM reduced breeding sites,the entomology index,and parasite rates.Results were heterogeneous,with variable magnitudes,but in all cases were favourable to the intervention.Evidence of IVM impacts on health outcomes was very limited but showed reduced incidence.Social outcomes were improved abilities and capacities,empowerment,and community knowledge.Regarding economic evaluation,only four studies performed an economic analysis,and intervention benefits outweighed costs.Costeffectiveness was dependent on illness incidence.The results provided key elements to analyze sustainability in terms of three dimensions(social,economic,and environmental),emphasizing the implementation of a community-focused eco-bio-social approach.Conclusions:IVM has an impact on reducing vector breeding sites and the entomology in展开更多
文摘Aiming at the problem that the traditional Unscented Kalman Filtering(UKF) algorithm can't solve the problem that the measurement covariance matrix is unknown and the measured value contains outliers,this paper proposes a robust adaptive UKF algorithm based on Support Vector Regression(SVR).The algorithm combines the advantages of support vector regression with small samples,nonlinear learning ability and online estimation capability of adaptive algorithm based on innovation.Firstly,the SVR model is trained by using the innovation in the sliding window,and the new innovation is monitored.If the deviation between the estimated innovation and the measured innovation exceeds a given threshold,then measured innovation will be replaced by the predicted innovation,and then the processed innovation is used to calculate the measurement noise covariance matrix using the adaptive estimation algorithm.Simulation experiments and measured data experiments show that SVRUKF is significantly better than the traditional UKF,robust UKF and adaptive UKF algorithms for the case where the covariance matrix is unknown and the measured values have outliers.
基金supported by the National Natural Science Foundation of China(7190121061973310).
文摘Solar arrays are important and indispensable parts of spacecraft and provide energy support for spacecraft to operate in orbit and complete on-orbit missions.When a spacecraft is in orbit,because the solar array is exposed to the harsh space environment,with increasing working time,the performance of its internal electronic components gradually degrade until abnormal damage occurs.This damage makes solar array power generation unable to fully meet the energy demand of a spacecraft.Therefore,timely and accurate detection of solar array anomalies is of great significance for the on-orbit operation and maintenance management of spacecraft.In this paper,we propose an anomaly detection method for spacecraft solar arrays based on the integrated least squares support vector machine(ILS-SVM)model:it selects correlated telemetry data from spacecraft solar arrays to form a training set and extracts n groups of training subsets from this set,then gets n corresponding least squares support vector machine(LS-SVM)submodels by training on these training subsets,respectively;after that,the ILS-SVM model is obtained by integrating these submodels through a weighting operation to increase the prediction accuracy and so on;finally,based on the obtained ILS-SVM model,a parameterfree and unsupervised anomaly determination method is proposed to detect the health status of solar arrays.We use the telemetry data set from a satellite in orbit to carry out experimental verification and find that the proposed method can diagnose solar array anomalies in time and can capture the signs before a solar array anomaly occurs,which reflects the applicability of the method.
基金the Astronautic Technology Foundation (HTZC0405)
文摘In view of the problem that the current single-antenna GPS attitude determination system can only determine the body attitude when the sideslip angle is zero and the multiantenna GPS/SINS integrated navigation system is of large volume, high cost, and complex structure, this approach is presented to determine the attitude based on vector space with single-antenna GPS and accelerometers in the micro inertial measurement unit （MIMU）. It can provide real-time and accurate attitude information. Subsequently, the single-antenna GPS/SINS integrated navigation system is designed based on the combination of position, velocity, and attitude. Finally the semi- physical simulations of single-antenna GPS attitude determination system and single-antenna GPS/SINS integrated navigation system are carried out. The simulation results, based on measured data, show that the single-antenna GPS/SINS system can provide more accurate navigation information compared to the GPS/SINS system, based on the combination of position and velocity. Furthermore, the single-antenna GPS/SINS system is characteristic of lower cost and simpler structure. It provides the basis for the application of a single-antenna GPS/SINS integrated navigation system in a micro aerial vehicle （MAV）.
基金the National Natural Science Foundation of China(Grant No.51537001)Fund of“Taishan Scholar”Climbing Plan of Shandong Province,China。
文摘Herein,we propose a novel three-phase quasi-Z-source inverter with a high voltage transmission ratio to address challenges such as high switching loss and sizeable magnetic components in the basic quasi-Z-source inverter.The proposed circuit topology,control strategy,and related analysis are presented.The circuit topology of the inverter comprises a quasi-Z-source network with an integrated magnetic inductor,an active clamp circuit,a three-phase inverter bridge,and an output LC filter,all of which are connected in series.An improved 12-sector space vector modulation scheme is proposed based on the root-mean-square value of the voltage and the instantaneous value of the current.Furthermore,analyses of the inverter voltage transmission ratio,resonant process,and parametric design guidelines for integrated magnetic inductor and zero-voltage switching conditions are presented.Experimental results on a 1-kVA prototype inverter demonstrate that the proposed inverter exhibits a higher transmission ratio and efficiency than existing inverters;thus,the proposed inverter would have broad prospects in low-voltage DC-AC applications.
文摘Background:The control of vector-borne diseases(VBD)is one of the greatest challenges on the global health agenda.Rapid and uncontrolled urbanization has heightened the interest in addressing these challenges through an integrated vector management(IVM)approach.The aim was to identify components related to impacts,economic evaluation,and sustainability that might contribute to this integrated approach to VBD prevention.Main body:We conducted a scoping review of available literature(2000-2016)using PubMed,Web of Science,Cochrane,CINAHL,Econlit,LILACS,Global Health Database,Scopus,and Embase,as well as Tropical Diseases Bulletin,WHOLIS,WHO Pesticide Evaluation Scheme,and Google Scholar.MeSH terms and free-text terms were used.A data extraction form was used,including TIDieR and ASTAIRE.MMAT and CHEERS were used to evaluate quality.Of the 42 documents reviewed,30 were focused on dengue,eight on malaria,and two on leishmaniasis.More than a half of the studies were conducted in the Americas.Half used a quantitative descriptive approach(n=21),followed by cluster randomized controlled trials(n=11).Regarding impacts,outcomes were:a)use of measures for vector control;b)vector control;c)health measures;and d)social measures.IVM reduced breeding sites,the entomology index,and parasite rates.Results were heterogeneous,with variable magnitudes,but in all cases were favourable to the intervention.Evidence of IVM impacts on health outcomes was very limited but showed reduced incidence.Social outcomes were improved abilities and capacities,empowerment,and community knowledge.Regarding economic evaluation,only four studies performed an economic analysis,and intervention benefits outweighed costs.Costeffectiveness was dependent on illness incidence.The results provided key elements to analyze sustainability in terms of three dimensions(social,economic,and environmental),emphasizing the implementation of a community-focused eco-bio-social approach.Conclusions:IVM has an impact on reducing vector breeding sites and the entomology in
