Microelectromechanical systems(MEMS)technology has gained significant attention over the past decade for measuring inertial angular velocity.However,due to inherent complexity,MEMS gyroscopes typically feature up to t...Microelectromechanical systems(MEMS)technology has gained significant attention over the past decade for measuring inertial angular velocity.However,due to inherent complexity,MEMS gyroscopes typically feature up to ten times more parameters than traditional sensors,making selection a challenging task even for experts.This study addresses this challenge,focusing on defensive guidance,navigation,and control(GNC)systems where precise and reliable angular velocity measurement is critical to overall performance.A comprehensive mathematical model is introduced to encapsulate all key MEMS parameters,accompanied by discussions on calibration and Allan variance interpretation.For six leading MEMS gyroscope applications,namely inertial navigation,integrated navigation,autopilot systems,rotating projectiles,homing guidance,and north finding,the most critical parameters are identified,distinguishing suitable and unsuitable sensor choices.Special emphasis is placed on inertial navigation systems,where practical rules of thumb for error evaluation are derived using six degrees of freedom motion equations.Rigorous simulations demonstrate the influence of various sensor parameters through real-world case studies,including static navigation,multi-rotor attitude estimation,gimbal stabilization,and north finding via a turntable.This work aims to be a beacon for practitioners across diverse fields,empowering them to make more informed design decisions.展开更多
As one of the major volatile components in extraterrestrial materials,nitrogen(N_(2))isotopes serve not only as tracers for the formation and evolution of the solar system,but also play a critical role in assessing pl...As one of the major volatile components in extraterrestrial materials,nitrogen(N_(2))isotopes serve not only as tracers for the formation and evolution of the solar system,but also play a critical role in assessing planetary habitability and the search for extraterrestrial life.The integrated measurement of N_(2)and argon(Ar)isotopes by using noble gas mass spectrometry represents a state-of-the-art technique for such investigations.To support the growing demands of planetary science research in China,we have developed a high-efficiency,high-precision method for the integrated analysis of N_(2)and Ar isotopes.This was achieved by enhancing gas extraction and purification systems and integrating them with a static noble gas mass spectrometer.This method enables integrated N_(2)-Ar isotope measurements on submilligram samples,significantly improving sample utilization and reducing the impact of sample heterogeneity on volatile analysis.The system integrates CO_(2)laser heating,a modular two-stage Zr-Al getter pump,and a CuO furnace-based purification process,effectively reducing background levels(N_(2)blank as low as 0.35×10^(−6)cubic centimeters at standard temperature and pressure[ccSTP]).Analytical precision is ensured through calibration with atmospheric air and CO corrections.To validate the reliability of the method,we performed N_(2)-Ar isotope analyses on the Allende carbonaceous chondrite,one of the most extensively studied meteorites internationally.The measured N_(2)concentrations range from 19.2 to 29.8 ppm,withδ15N values between−44.8‰and−33.0‰.Concentrations of 40Ar,36Ar,and 38Ar are(12.5-21.1)×10^(−6)ccSTP/g,(90.9-150.3)×10^(−9)ccSTP/g,and(19.2-30.7)×10^(−9)ccSTP/g,respectively.These values correspond to cosmic-ray exposure ages of 4.5-5.7 Ma,consistent with previous reports.Step-heating experiments further reveal distinct release patterns of N and Ar isotopes,as well as their associations with specific mineral phases in the meteorite.In summary,the combined N_(2)-Ar isotopic system offers significant advantages for tracing volatile sources in extraterrestrial materials and will provide essential analytical support for upcoming Chinese planetary missions,such as Tianwen-2.展开更多
At the stage of preliminary scheme and algorithm design for spaceborne navigation systems, a precise and high-fidelity software global positioning system （GPS） simulator is a necessary and feasible testing facility ...At the stage of preliminary scheme and algorithm design for spaceborne navigation systems, a precise and high-fidelity software global positioning system （GPS） simulator is a necessary and feasible testing facility in laboratory environments, with consideration of the tradeoffs where possible. This article presents a software GPS measurements simulator on the L1 C/A code and carrier signal for space-oriented navigation system design. The simulator, coded in MATLAB language, generates both C/A code pseudorange and carrier phase measurements. Mathematical models in the Earth centered inertial （ECI） frame are formulated to simulate the GPS constellation and to generate GPS measurements. A series of efficient measures are investigated and utilized to rationalize the enhanced simulator, in terms of ephemeris data selection, space ionospheric model and range rate calculation, etc. Such an enhanced simulator has been facilitating our current work for designing a space integrated GPS/inertial navigation system （INS） navigation system. Consequently, it will promote our future research on space-oriented navigation system.展开更多
A new distributed fusion method of radar/infrared （IR） tracking system based on separation and combination of the measurements is proposed by analyzing the influence of rate measurement. The rate information separat...A new distributed fusion method of radar/infrared （IR） tracking system based on separation and combination of the measurements is proposed by analyzing the influence of rate measurement. The rate information separated from the radar measurements together with measurements of IR form a pseudo vector of IR, and the corresponding filter is designed. The results indicate that the method not only makes a great improvement to the local tracker＇s performance, but also improves the global tracking precision efficiently.展开更多
Without the known state equation, a new state estimation strategy is designed to be against malicious attacks for cyber physical systems. Inspired by the idea of data reconstruction, the compressive sensing （CS） is ...Without the known state equation, a new state estimation strategy is designed to be against malicious attacks for cyber physical systems. Inspired by the idea of data reconstruction, the compressive sensing （CS） is applied to reconstruction of residual measurements after the detection and identification scheme based on the Markov graph of the system state, which increases the resilience of state estimation strategy against deception attacks. First, the observability analysis is introduced to decide the triggering time of the measurement reconstruction and the damage level from attacks. In particular, the dictionary learning is proposed to form the over-completed dictionary by K-singular value decomposition （K-SVD）, which is produced adaptively according to the characteristics of the measurement data. In addition, due to the irregularity of residual measurements, a sampling matrix is designed as the measurement matrix. Finally, the simulation experiments are performed on 6-bus power system. Results show that the reconstruction of measurements is completed well by the proposed reconstruction method, and the corresponding effects are better than reconstruction scheme based on the joint dictionary and the traditional Gauss or Bernoulli random matrix respectively. Especially, when only 29% available clean measurements are left, performance of the proposed strategy is still extraordinary, which reflects generality for five kinds of recovery algorithms.展开更多
This paper deals with the problem of active disturbance rejection control(ADRC)design for a class of uncertain nonlinear systems with sporadic measurements.A novel extended state observer(ESO)is designed in a cascade ...This paper deals with the problem of active disturbance rejection control(ADRC)design for a class of uncertain nonlinear systems with sporadic measurements.A novel extended state observer(ESO)is designed in a cascade form consisting of a continuous time estimator,a continuous observation error predictor,and a reset compensator.The proposed ESO estimates not only the system state but also the total uncertainty,which may include the effects of the external perturbation,the parametric uncertainty,and the unknown nonlinear dynamics.Such a reset compensator,whose state is reset to zero whenever a new measurement arrives,is used to calibrate the predictor.Due to the cascade structure,the resulting error dynamics system is presented in a non-hybrid form,and accordingly,analyzed in a general sampled-data system framework.Based on the output of the ESO,a continuous ADRC law is then developed.The convergence of the resulting closed-loop system is proved under given conditions.Two numerical simulations demonstrate the effectiveness of the proposed control method.展开更多
Noise measurements are especially a problem when the object under investigation is largely dimensioned and can only be measured from the distance. To obtain information about the location of noise generation, a measur...Noise measurements are especially a problem when the object under investigation is largely dimensioned and can only be measured from the distance. To obtain information about the location of noise generation, a measurement technique which makes sound visible in order to introduce further specific technical measures is advantageous. The question is if the time dependence of the signal got from such a non touching and non destructive acoustic method has the potential to calculate the materials damping from. Using a small sound source localization system （Microflown^TM probe）, specimens of magnesium alloys with different grain sizes obtained by hydrostatic extrusion were investigated. It has been demonstrated that the fine grained microstructure led to a lower damping and its dependence on the strain was reduced. In this context, acoustic measurements by a sound source localisation system which makes materials characterization possible could be used as a quality tool to detect changes in highly stressed components. This approach allows to promote a selective substitution of conventional materials by more innovative ones. The offshore sector is considered to be a field of application： Wind turbines produce noise emission which stems mainly from turbulences at the tips of the rotor blades and vibrations of components inside the nacelle （e.9. gearbox, generator, ...）. If the vibration amplitudes are too high, microcracks of components can lead to failure over the long term. The monitoring of microstructural changes using a larger type of a sound source localisation system is considered as an innovative technical approach with respect to maintenance activities.展开更多
The Aircraft Integrated Meteorological Measuring System 20 Hz(AIMMS-20) has been used by the Hong Kong Observatory(HKO),China in data collection for tropical cyclone situations over the South China Sea and windshear a...The Aircraft Integrated Meteorological Measuring System 20 Hz(AIMMS-20) has been used by the Hong Kong Observatory(HKO),China in data collection for tropical cyclone situations over the South China Sea and windshear and turbulence measurement at the Hong Kong International Airport(HKIA).This paper discusses possible methods for further enhancing the quality of the wind and temperature measurements from the system.For wind measurement,the enhancement methods include:error modelling of the accelerometer(e.g.,bias offset and cross-axis rate sensitivity),global positioning system(GPS) phase lag consideration,better representation of the inertial measurement unit(IMU) velocity based on the GPS velocities and considering their location differences,consideration of the slower update of GPS velocity,and wing flexure.For temperature measurement,the methods include the consideration of the temperature sensor response and the sensor housing response.The results of typical flights using AIMMS-20 show that the accuracy of the wind and temperature data could be improved by 20%-30%.Though the discussion in the present paper is related mainly to a specific meteorological measuring system on a particular aircraft,the techniques so employed should be a useful reference for similar systems installed on other aircraft.展开更多
This paper is concerned with the problem of robust H-infinity filtering on uncertain systems under sampled measurements, both continuous disturbance and discrete disturbance are considered in the systems. The paramete...This paper is concerned with the problem of robust H-infinity filtering on uncertain systems under sampled measurements, both continuous disturbance and discrete disturbance are considered in the systems. The parameter uncertainty is assumed to be time-varying norm-bounded. The aim is to design an asymptotically stable filter, using the locally sampled measurements, which ensures both the robust asymptotic stability and a prescribed level of H-infinity performance for the filtering error dynamics for all admissible uncertainties. The derivation process is simplified by introducing auxiliary systems and the sufficient condition for the existence of such a filter is proposed. During the study, the main results were expressed as LMIs by employing various matrix techniques. Using LMI toolbox of Matlab software, it is very convenient to obtain the appropriate filter. Finally, a numerical example shows that the method is effective and feasible.展开更多
We investigate asymptotical stabilization for a class of chaotic systems by means of quantization measurements of states.The quantizer adopted in this paper takes finite many values.In particular,one zoomer is placed ...We investigate asymptotical stabilization for a class of chaotic systems by means of quantization measurements of states.The quantizer adopted in this paper takes finite many values.In particular,one zoomer is placed at the input terminal of the quantizer,and another zoomer is located at the output terminal of the quantizer.The zoomers possess a common adjustable time-varying parameter.By using the adaptive laws for the time-varying parameter and estimating boundary error of values of quantization,the stabilization feedback controller with the quantized state measurements is proposed for a class of chaotic systems.Finally,some numerical examples are given to demonstrate the validity of the proposed methods.展开更多
In this paper, the measurement method of calorimetric power for an electron cyclotron resonance heating（ECRH） system for EAST is presented. This method requires measurements of the water flow through the cooling cir...In this paper, the measurement method of calorimetric power for an electron cyclotron resonance heating（ECRH） system for EAST is presented. This method requires measurements of the water flow through the cooling circuits and the input and output water temperatures in each cooling circuit. Usually, the inlet water temperature stability is controlled to obtain more accurate results.The influence of the inlet water temperature change on the measurement results is analyzed for the first time in this paper. Also, a novel temperature calibration method is proposed. This kind of calibration method is accurate and effective, and can be easily implemented.展开更多
By considering a 3-mode optomechanical system formed by two cavities interacting with a common mechanical mode,we demonstrate that phonon-counting measurements lead to a significant enhancement of entanglement in the ...By considering a 3-mode optomechanical system formed by two cavities interacting with a common mechanical mode,we demonstrate that phonon-counting measurements lead to a significant enhancement of entanglement in the output of the two cavities.This conclusion still holds for an inefficient detector,but the dependence on system parameters changes qualitatively from the ideal limit of perfect projective measurements.We find non-trivial optimal points for the entanglement as functions of detector efficiency,measurement outcome,and optical drive strengths.We characterize both the highest achievable entanglement as well as a‘typical’value,obtained at the most likely measurement outcome.Numerical results are well understood within an approximate analytical approach based on perturbation theory around the ideal detector limit.展开更多
We study the quenched random disorder(QRD) effects created by aerosil dispersion in the octylcyanobiphenyl(8CB) liquid crystal(LC) using atomic force microscopy technique. Gelation process in the 8CB+aerosil gels yiel...We study the quenched random disorder(QRD) effects created by aerosil dispersion in the octylcyanobiphenyl(8CB) liquid crystal(LC) using atomic force microscopy technique. Gelation process in the 8CB+aerosil gels yields a QRD network which also changes the surface topography. By increasing the aerosil concentration, the original smooth pattern of LC sample surfaces is suppressed by the emergence of a fractal aerosil surface effect and these surfaces become more porous, rougher and they have more and larger crevices. The dispersed aerosil also serves as pinning centers for the liquid crystal molecules. It is observed that via the diffusion-limitedaggregation process, aerosil nano-particles yield a fractal-like surface pattern for the less disordered samples. As the aerosil dispersion increases, the surface can be described by more aggregated regions, which also introduces more roughness. Using this fact, we show that there is a net correlation between the short-range ordered x-ray peak widths(the results of previous x-ray diffraction experiments) and the calculated surface roughness. In other words, we show that these QRD gels can also be characterized by their surface roughness values.展开更多
This paper investigates asymptotic bounded consensus tracking（ABCT） of double-integrator multi-agent systems（MASs） with an asymptotically-unbounded-acceleration and bounded-jerk target（AUABJT） available to parti...This paper investigates asymptotic bounded consensus tracking（ABCT） of double-integrator multi-agent systems（MASs） with an asymptotically-unbounded-acceleration and bounded-jerk target（AUABJT） available to partial agents based on sampled-data without velocity measurements. A sampled-data consensus tracking protocol（CTP） without velocity measurements is proposed to guarantee that double-integrator MASs track an AUABJT available to only partial agents.The eigenvalue analysis method together with the augmented matrix method is used to obtain the necessary and sufficient conditions for ABCT. A numerical example is provided to illustrate the effectiveness of theoretical results.展开更多
Robust H-infinity filtering for a class of uncertain discrete-time linear systems with time delays and missing measurements is studied in this paper. The uncertain parameters are supposed to reside in a convex polytop...Robust H-infinity filtering for a class of uncertain discrete-time linear systems with time delays and missing measurements is studied in this paper. The uncertain parameters are supposed to reside in a convex polytope and the missing measurements are described by a binary switching sequence satisfying a Bernoulli distribution. Our attention is focused on the analysis and design of robust H-infinity filters such that, for all admissible parameter uncertainties and all possible missing measurements, the filtering error system is exponentially mean-square stable with a prescribed H-infinity disturbance attenuation level. A parameter-dependent approach is proposed to derive a less conservative result. Sufficient conditions are established for the existence of the desired filter in terms of certain linear matrix inequalities （LMIs）. When these LMIs are feasible, an explicit expression of the desired filter is also provided. Finally, a numerical example is presented to illustrate the effectiveness and applicability of the proposed method.展开更多
Most currently existing investigations on the observability of passive guidance systems can only provide a qualitative result. In this paper, a quantitative method, which utilizes Cramér-Rao lower bound in the es...Most currently existing investigations on the observability of passive guidance systems can only provide a qualitative result. In this paper, a quantitative method, which utilizes Cramér-Rao lower bound in the estimability analysis of closed-loop guidance systems with bearings-only measurements, is proposed. The new method provides an intuitive result for observability of the guidance system through graphical analysis. As a demonstration, a numerical example is presented, in which the degrees of observability of the guidance systems under two commonly used guidance laws are compared by using the new approach.展开更多
In this paper,we explore how to estimate the phase damping parameter γ and the tunneling amplitude parameter ？from a spin-boson dephasing quantum model by periodical projective measurements.The preparation of initia...In this paper,we explore how to estimate the phase damping parameter γ and the tunneling amplitude parameter ？from a spin-boson dephasing quantum model by periodical projective measurements.The preparation of initial states is accomplished by performing the period measurements in our scheme.The parameter γ can be always estimated when projective measurement bases are chosen as θ = π/2 and φ = 0.Based on the estimated value of γ and the interval information of ？,we can select another measurement bases（θ = π/4 and φ = π/2） to obtain the estimated value of ？.A coherent control is indispensable to estimate ？ if γ is in the interval of ？;whereas the control is not necessary if γ is out of the known interval of ？.We establish the relation between the optimal period time and the parameter γ or ？ in terms of Fisher information.Although the optimal measurement period cannot be selected beforehand,the aforementioned relation can be utilized to adjust the measurement period to approach the optimal one.展开更多
This paper investigates the problem of robust H!fixed-order dynamic output feedback( DOF)controller design for a class of Takagi-Sugeno( T-S) fuzzy affine systems using quantized measurements.Through a state-input aug...This paper investigates the problem of robust H!fixed-order dynamic output feedback( DOF)controller design for a class of Takagi-Sugeno( T-S) fuzzy affine systems using quantized measurements.Through a state-input augmentation method,some sufficient conditions for controller synthesis are developed based upon piecewise quadratic Lyapunov functions( PQLFs) in terms of LMIs. Two illustrative studies are conducted to verify the effectiveness of the proposed controller synthesis approach.展开更多
Background and Aim: Irradiation methods such as double scattering method and spot scanning method have been used in proton beam treatment devices. In the scattering method, a ridge filter or a range modulation wheel i...Background and Aim: Irradiation methods such as double scattering method and spot scanning method have been used in proton beam treatment devices. In the scattering method, a ridge filter or a range modulation wheel is used to create a spread-out Bragg peak, but the distribution at the patient position may change due to positional deviation of the incident beam. Therefore, assessment of the incident position of the beam is very important even in the scattering method. To investigate the width and distribution of the proton beam before entering the RMW, a radiochromic film was installed at the outlet of the transport pipe and the entrance of the profile-monitoring detector. Methods: In this study, the distributions of the beam at the exit of the transport pipe and the entrance of the monitor detector were measured using films. The beam width was measured from the full width at half maximum of the profile obtained from the distribution. Measurements were conducted every month for 10 months. Results: Beams of widths ranging from 1.82 to 2.30 mm in the horizontal direction and 4.25 to 5.33 mm in the vertical direction were outputted from the exit of the transport pipe. Beams of widths ranging from 2.16 to 2.67 mm in the horizontal direction and 4.06 to 5.31 mm in the vertical direction were outputted from the entrance of the monitor detector. The maximum width fluctuation for 10 months was 0.55 mm in the horizontal direction and 1.26 mm in the vertical direction at the entrance of the monitor detector. Conclusions: The distribution was obtained before the proton beam was scattered by the scatterer, and then we propose a method to periodically measure and monitor the changes in the beam distributions every month.展开更多
This article studies distributed pose(orientation and position)estimation of leader–follower multi-agent systems over𝜅-layer graphs in 2-D plane.Only the leaders have access to their orientations and position...This article studies distributed pose(orientation and position)estimation of leader–follower multi-agent systems over𝜅-layer graphs in 2-D plane.Only the leaders have access to their orientations and positions,while the followers can measure the relative bearings or(angular and linear)velocities in their unknown local coordinate frames.For the orientation estimation,the local relative bearings are used to obtain the relative orientations among the agents,based on which a distributed orientation estimation algorithm is proposed for each follower to estimate its orientation.For the position estimation,the local relative bearings are used to obtain the position constraints among the agents,and a distributed position estimation algorithm is proposed for each follower to estimate its position by solving its position constraints.Both the orientation and position estimation errors converge to zero asymptotically.A simulation example is given to verify the theoretical results.展开更多
文摘Microelectromechanical systems(MEMS)technology has gained significant attention over the past decade for measuring inertial angular velocity.However,due to inherent complexity,MEMS gyroscopes typically feature up to ten times more parameters than traditional sensors,making selection a challenging task even for experts.This study addresses this challenge,focusing on defensive guidance,navigation,and control(GNC)systems where precise and reliable angular velocity measurement is critical to overall performance.A comprehensive mathematical model is introduced to encapsulate all key MEMS parameters,accompanied by discussions on calibration and Allan variance interpretation.For six leading MEMS gyroscope applications,namely inertial navigation,integrated navigation,autopilot systems,rotating projectiles,homing guidance,and north finding,the most critical parameters are identified,distinguishing suitable and unsuitable sensor choices.Special emphasis is placed on inertial navigation systems,where practical rules of thumb for error evaluation are derived using six degrees of freedom motion equations.Rigorous simulations demonstrate the influence of various sensor parameters through real-world case studies,including static navigation,multi-rotor attitude estimation,gimbal stabilization,and north finding via a turntable.This work aims to be a beacon for practitioners across diverse fields,empowering them to make more informed design decisions.
基金supported by the Bureau of Frontier Sciences and Basic Research,Chinese Academy of Sciences(Grant No.QYJ-2025-0103)the National Natural Science Foundation of China(Grant Nos.42441834,42241105,42441825,and 42203048)the Key Research Program of the Institute of Geology and Geophysics,Chinese Academy of Sciences(Grant No.IGGCAS-202401).
文摘As one of the major volatile components in extraterrestrial materials,nitrogen(N_(2))isotopes serve not only as tracers for the formation and evolution of the solar system,but also play a critical role in assessing planetary habitability and the search for extraterrestrial life.The integrated measurement of N_(2)and argon(Ar)isotopes by using noble gas mass spectrometry represents a state-of-the-art technique for such investigations.To support the growing demands of planetary science research in China,we have developed a high-efficiency,high-precision method for the integrated analysis of N_(2)and Ar isotopes.This was achieved by enhancing gas extraction and purification systems and integrating them with a static noble gas mass spectrometer.This method enables integrated N_(2)-Ar isotope measurements on submilligram samples,significantly improving sample utilization and reducing the impact of sample heterogeneity on volatile analysis.The system integrates CO_(2)laser heating,a modular two-stage Zr-Al getter pump,and a CuO furnace-based purification process,effectively reducing background levels(N_(2)blank as low as 0.35×10^(−6)cubic centimeters at standard temperature and pressure[ccSTP]).Analytical precision is ensured through calibration with atmospheric air and CO corrections.To validate the reliability of the method,we performed N_(2)-Ar isotope analyses on the Allende carbonaceous chondrite,one of the most extensively studied meteorites internationally.The measured N_(2)concentrations range from 19.2 to 29.8 ppm,withδ15N values between−44.8‰and−33.0‰.Concentrations of 40Ar,36Ar,and 38Ar are(12.5-21.1)×10^(−6)ccSTP/g,(90.9-150.3)×10^(−9)ccSTP/g,and(19.2-30.7)×10^(−9)ccSTP/g,respectively.These values correspond to cosmic-ray exposure ages of 4.5-5.7 Ma,consistent with previous reports.Step-heating experiments further reveal distinct release patterns of N and Ar isotopes,as well as their associations with specific mineral phases in the meteorite.In summary,the combined N_(2)-Ar isotopic system offers significant advantages for tracing volatile sources in extraterrestrial materials and will provide essential analytical support for upcoming Chinese planetary missions,such as Tianwen-2.
基金Research Fund of Shanghai Academy of Spaceflight Technology
文摘At the stage of preliminary scheme and algorithm design for spaceborne navigation systems, a precise and high-fidelity software global positioning system （GPS） simulator is a necessary and feasible testing facility in laboratory environments, with consideration of the tradeoffs where possible. This article presents a software GPS measurements simulator on the L1 C/A code and carrier signal for space-oriented navigation system design. The simulator, coded in MATLAB language, generates both C/A code pseudorange and carrier phase measurements. Mathematical models in the Earth centered inertial （ECI） frame are formulated to simulate the GPS constellation and to generate GPS measurements. A series of efficient measures are investigated and utilized to rationalize the enhanced simulator, in terms of ephemeris data selection, space ionospheric model and range rate calculation, etc. Such an enhanced simulator has been facilitating our current work for designing a space integrated GPS/inertial navigation system （INS） navigation system. Consequently, it will promote our future research on space-oriented navigation system.
基金supported by the National Natural Science Foundation of China (60574022).
文摘A new distributed fusion method of radar/infrared （IR） tracking system based on separation and combination of the measurements is proposed by analyzing the influence of rate measurement. The rate information separated from the radar measurements together with measurements of IR form a pseudo vector of IR, and the corresponding filter is designed. The results indicate that the method not only makes a great improvement to the local tracker＇s performance, but also improves the global tracking precision efficiently.
基金This work was supported by the Natural Science Foundation of China （NSFC）-Guangdong Joint Foundation Key Project （No. U1401253）, the NSFC （Nos. 61573153, 616721 74）, the Foundation of Guangdong Provincial Science and Technology Projects （No. 2013B010401001 ）, the Fundamental Research Funds for the Central Universities （No. 2015ZZ099）, the Guangzhou Science and Technology Plan Project （No. 201510010132）, the Maoming Science and Technology Plan Project （No. MM201 7000004）, and the National Natural Science Foundation of Guangdong Province （No. 2016A030313510）.
文摘Without the known state equation, a new state estimation strategy is designed to be against malicious attacks for cyber physical systems. Inspired by the idea of data reconstruction, the compressive sensing （CS） is applied to reconstruction of residual measurements after the detection and identification scheme based on the Markov graph of the system state, which increases the resilience of state estimation strategy against deception attacks. First, the observability analysis is introduced to decide the triggering time of the measurement reconstruction and the damage level from attacks. In particular, the dictionary learning is proposed to form the over-completed dictionary by K-singular value decomposition （K-SVD）, which is produced adaptively according to the characteristics of the measurement data. In addition, due to the irregularity of residual measurements, a sampling matrix is designed as the measurement matrix. Finally, the simulation experiments are performed on 6-bus power system. Results show that the reconstruction of measurements is completed well by the proposed reconstruction method, and the corresponding effects are better than reconstruction scheme based on the joint dictionary and the traditional Gauss or Bernoulli random matrix respectively. Especially, when only 29% available clean measurements are left, performance of the proposed strategy is still extraordinary, which reflects generality for five kinds of recovery algorithms.
基金supported by the National Natural Science Foundation of China(61833016,61873295).
文摘This paper deals with the problem of active disturbance rejection control(ADRC)design for a class of uncertain nonlinear systems with sporadic measurements.A novel extended state observer(ESO)is designed in a cascade form consisting of a continuous time estimator,a continuous observation error predictor,and a reset compensator.The proposed ESO estimates not only the system state but also the total uncertainty,which may include the effects of the external perturbation,the parametric uncertainty,and the unknown nonlinear dynamics.Such a reset compensator,whose state is reset to zero whenever a new measurement arrives,is used to calibrate the predictor.Due to the cascade structure,the resulting error dynamics system is presented in a non-hybrid form,and accordingly,analyzed in a general sampled-data system framework.Based on the output of the ESO,a continuous ADRC law is then developed.The convergence of the resulting closed-loop system is proved under given conditions.Two numerical simulations demonstrate the effectiveness of the proposed control method.
文摘Noise measurements are especially a problem when the object under investigation is largely dimensioned and can only be measured from the distance. To obtain information about the location of noise generation, a measurement technique which makes sound visible in order to introduce further specific technical measures is advantageous. The question is if the time dependence of the signal got from such a non touching and non destructive acoustic method has the potential to calculate the materials damping from. Using a small sound source localization system （Microflown^TM probe）, specimens of magnesium alloys with different grain sizes obtained by hydrostatic extrusion were investigated. It has been demonstrated that the fine grained microstructure led to a lower damping and its dependence on the strain was reduced. In this context, acoustic measurements by a sound source localisation system which makes materials characterization possible could be used as a quality tool to detect changes in highly stressed components. This approach allows to promote a selective substitution of conventional materials by more innovative ones. The offshore sector is considered to be a field of application： Wind turbines produce noise emission which stems mainly from turbulences at the tips of the rotor blades and vibrations of components inside the nacelle （e.9. gearbox, generator, ...）. If the vibration amplitudes are too high, microcracks of components can lead to failure over the long term. The monitoring of microstructural changes using a larger type of a sound source localisation system is considered as an innovative technical approach with respect to maintenance activities.
文摘The Aircraft Integrated Meteorological Measuring System 20 Hz(AIMMS-20) has been used by the Hong Kong Observatory(HKO),China in data collection for tropical cyclone situations over the South China Sea and windshear and turbulence measurement at the Hong Kong International Airport(HKIA).This paper discusses possible methods for further enhancing the quality of the wind and temperature measurements from the system.For wind measurement,the enhancement methods include:error modelling of the accelerometer(e.g.,bias offset and cross-axis rate sensitivity),global positioning system(GPS) phase lag consideration,better representation of the inertial measurement unit(IMU) velocity based on the GPS velocities and considering their location differences,consideration of the slower update of GPS velocity,and wing flexure.For temperature measurement,the methods include the consideration of the temperature sensor response and the sensor housing response.The results of typical flights using AIMMS-20 show that the accuracy of the wind and temperature data could be improved by 20%-30%.Though the discussion in the present paper is related mainly to a specific meteorological measuring system on a particular aircraft,the techniques so employed should be a useful reference for similar systems installed on other aircraft.
基金This work was supported by the National Natural Science Foundation of China (No.60274009) and the National Program (863) of High TechnologyDevelopment(No.2004AA412030).
文摘This paper is concerned with the problem of robust H-infinity filtering on uncertain systems under sampled measurements, both continuous disturbance and discrete disturbance are considered in the systems. The parameter uncertainty is assumed to be time-varying norm-bounded. The aim is to design an asymptotically stable filter, using the locally sampled measurements, which ensures both the robust asymptotic stability and a prescribed level of H-infinity performance for the filtering error dynamics for all admissible uncertainties. The derivation process is simplified by introducing auxiliary systems and the sufficient condition for the existence of such a filter is proposed. During the study, the main results were expressed as LMIs by employing various matrix techniques. Using LMI toolbox of Matlab software, it is very convenient to obtain the appropriate filter. Finally, a numerical example shows that the method is effective and feasible.
基金Supported by the National Science Foundation of China under Grant No.11172017the Guangdong Natural Science Foundation under Grant No.8151009001000061Natural Science Joint Research Program Foundation of Guangdong Province under Grant No.8351009001000002
文摘We investigate asymptotical stabilization for a class of chaotic systems by means of quantization measurements of states.The quantizer adopted in this paper takes finite many values.In particular,one zoomer is placed at the input terminal of the quantizer,and another zoomer is located at the output terminal of the quantizer.The zoomers possess a common adjustable time-varying parameter.By using the adaptive laws for the time-varying parameter and estimating boundary error of values of quantization,the stabilization feedback controller with the quantized state measurements is proposed for a class of chaotic systems.Finally,some numerical examples are given to demonstrate the validity of the proposed methods.
基金supported by the National Magnetic Confinement Fusion Science Program of China (Grant Nos.2011GB102000, 2015GB103000)
文摘In this paper, the measurement method of calorimetric power for an electron cyclotron resonance heating（ECRH） system for EAST is presented. This method requires measurements of the water flow through the cooling circuits and the input and output water temperatures in each cooling circuit. Usually, the inlet water temperature stability is controlled to obtain more accurate results.The influence of the inlet water temperature change on the measurement results is analyzed for the first time in this paper. Also, a novel temperature calibration method is proposed. This kind of calibration method is accurate and effective, and can be easily implemented.
基金support from NSFC(Grants No.11974040 and No.12150610464)NSAF(Grant No.U1930402)support from MOST(Grant No.2017YFA0304503)。
文摘By considering a 3-mode optomechanical system formed by two cavities interacting with a common mechanical mode,we demonstrate that phonon-counting measurements lead to a significant enhancement of entanglement in the output of the two cavities.This conclusion still holds for an inefficient detector,but the dependence on system parameters changes qualitatively from the ideal limit of perfect projective measurements.We find non-trivial optimal points for the entanglement as functions of detector efficiency,measurement outcome,and optical drive strengths.We characterize both the highest achievable entanglement as well as a‘typical’value,obtained at the most likely measurement outcome.Numerical results are well understood within an approximate analytical approach based on perturbation theory around the ideal detector limit.
文摘We study the quenched random disorder(QRD) effects created by aerosil dispersion in the octylcyanobiphenyl(8CB) liquid crystal(LC) using atomic force microscopy technique. Gelation process in the 8CB+aerosil gels yields a QRD network which also changes the surface topography. By increasing the aerosil concentration, the original smooth pattern of LC sample surfaces is suppressed by the emergence of a fractal aerosil surface effect and these surfaces become more porous, rougher and they have more and larger crevices. The dispersed aerosil also serves as pinning centers for the liquid crystal molecules. It is observed that via the diffusion-limitedaggregation process, aerosil nano-particles yield a fractal-like surface pattern for the less disordered samples. As the aerosil dispersion increases, the surface can be described by more aggregated regions, which also introduces more roughness. Using this fact, we show that there is a net correlation between the short-range ordered x-ray peak widths(the results of previous x-ray diffraction experiments) and the calculated surface roughness. In other words, we show that these QRD gels can also be characterized by their surface roughness values.
基金supported by the National Natural Science Foundation of China(Grant Nos.61203147,61374047,61473138,and 61403168)the Fundamental Research Funds for the Central Universities of China(Grant No.JUSRP51510)
文摘This paper investigates asymptotic bounded consensus tracking（ABCT） of double-integrator multi-agent systems（MASs） with an asymptotically-unbounded-acceleration and bounded-jerk target（AUABJT） available to partial agents based on sampled-data without velocity measurements. A sampled-data consensus tracking protocol（CTP） without velocity measurements is proposed to guarantee that double-integrator MASs track an AUABJT available to only partial agents.The eigenvalue analysis method together with the augmented matrix method is used to obtain the necessary and sufficient conditions for ABCT. A numerical example is provided to illustrate the effectiveness of theoretical results.
基金This work was supported by the National Natural Science Foundation of China(No.60574084)the National 863 Project(No.2006AA04Z428)the National 973 Program of China(No.2002CB312200).
文摘Robust H-infinity filtering for a class of uncertain discrete-time linear systems with time delays and missing measurements is studied in this paper. The uncertain parameters are supposed to reside in a convex polytope and the missing measurements are described by a binary switching sequence satisfying a Bernoulli distribution. Our attention is focused on the analysis and design of robust H-infinity filters such that, for all admissible parameter uncertainties and all possible missing measurements, the filtering error system is exponentially mean-square stable with a prescribed H-infinity disturbance attenuation level. A parameter-dependent approach is proposed to derive a less conservative result. Sufficient conditions are established for the existence of the desired filter in terms of certain linear matrix inequalities （LMIs）. When these LMIs are feasible, an explicit expression of the desired filter is also provided. Finally, a numerical example is presented to illustrate the effectiveness and applicability of the proposed method.
基金the National Natural Science Foundation of China (Grant No. 60104003 and 60374024).
文摘Most currently existing investigations on the observability of passive guidance systems can only provide a qualitative result. In this paper, a quantitative method, which utilizes Cramér-Rao lower bound in the estimability analysis of closed-loop guidance systems with bearings-only measurements, is proposed. The new method provides an intuitive result for observability of the guidance system through graphical analysis. As a demonstration, a numerical example is presented, in which the degrees of observability of the guidance systems under two commonly used guidance laws are compared by using the new approach.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61673389,61273202,and 61134008)
文摘In this paper,we explore how to estimate the phase damping parameter γ and the tunneling amplitude parameter ？from a spin-boson dephasing quantum model by periodical projective measurements.The preparation of initial states is accomplished by performing the period measurements in our scheme.The parameter γ can be always estimated when projective measurement bases are chosen as θ = π/2 and φ = 0.Based on the estimated value of γ and the interval information of ？,we can select another measurement bases（θ = π/4 and φ = π/2） to obtain the estimated value of ？.A coherent control is indispensable to estimate ？ if γ is in the interval of ？;whereas the control is not necessary if γ is out of the known interval of ？.We establish the relation between the optimal period time and the parameter γ or ？ in terms of Fisher information.Although the optimal measurement period cannot be selected beforehand,the aforementioned relation can be utilized to adjust the measurement period to approach the optimal one.
基金Sponsored by the National Natural Science Foundation of China(Grant No.61522306)
文摘This paper investigates the problem of robust H!fixed-order dynamic output feedback( DOF)controller design for a class of Takagi-Sugeno( T-S) fuzzy affine systems using quantized measurements.Through a state-input augmentation method,some sufficient conditions for controller synthesis are developed based upon piecewise quadratic Lyapunov functions( PQLFs) in terms of LMIs. Two illustrative studies are conducted to verify the effectiveness of the proposed controller synthesis approach.
文摘Background and Aim: Irradiation methods such as double scattering method and spot scanning method have been used in proton beam treatment devices. In the scattering method, a ridge filter or a range modulation wheel is used to create a spread-out Bragg peak, but the distribution at the patient position may change due to positional deviation of the incident beam. Therefore, assessment of the incident position of the beam is very important even in the scattering method. To investigate the width and distribution of the proton beam before entering the RMW, a radiochromic film was installed at the outlet of the transport pipe and the entrance of the profile-monitoring detector. Methods: In this study, the distributions of the beam at the exit of the transport pipe and the entrance of the monitor detector were measured using films. The beam width was measured from the full width at half maximum of the profile obtained from the distribution. Measurements were conducted every month for 10 months. Results: Beams of widths ranging from 1.82 to 2.30 mm in the horizontal direction and 4.25 to 5.33 mm in the vertical direction were outputted from the exit of the transport pipe. Beams of widths ranging from 2.16 to 2.67 mm in the horizontal direction and 4.06 to 5.31 mm in the vertical direction were outputted from the entrance of the monitor detector. The maximum width fluctuation for 10 months was 0.55 mm in the horizontal direction and 1.26 mm in the vertical direction at the entrance of the monitor detector. Conclusions: The distribution was obtained before the proton beam was scattered by the scatterer, and then we propose a method to periodically measure and monitor the changes in the beam distributions every month.
基金supported by Nanyang Technological University,Singapore under the Wallenberg-NTU Presidential Postdoctoral Fellowship and the Natural Science Foundation in Heilongjiang Province,China(YQ2022F003).
文摘This article studies distributed pose(orientation and position)estimation of leader–follower multi-agent systems over𝜅-layer graphs in 2-D plane.Only the leaders have access to their orientations and positions,while the followers can measure the relative bearings or(angular and linear)velocities in their unknown local coordinate frames.For the orientation estimation,the local relative bearings are used to obtain the relative orientations among the agents,based on which a distributed orientation estimation algorithm is proposed for each follower to estimate its orientation.For the position estimation,the local relative bearings are used to obtain the position constraints among the agents,and a distributed position estimation algorithm is proposed for each follower to estimate its position by solving its position constraints.Both the orientation and position estimation errors converge to zero asymptotically.A simulation example is given to verify the theoretical results.
