The Experts below are selected from a list of 4281 Experts worldwide ranked by ideXlab platform
Alessandro Astolfi - One of the best experts on this subject based on the ideXlab platform.
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A Geometric Characterization of the Persistence of Excitation Condition for the Solutions of Autonomous Systems
IEEE Transactions on Automatic Control, 2017Co-Authors: Alberto Padoan, Giordano Scarciotti, Alessandro AstolfiAbstract:The persistence of Excitation of signals generated by time-invariant, autonomous, linear, and nonlinear systems is studied using a geometric approach. A rank Condition is shown to be equivalent, under certain assumptions, to the persistence of Excitation of the solutions of the class of systems considered, both in the discrete-time and in the continuous-time settings. The rank Condition is geometric in nature and can be checked a priori, i.e. without knowing explicitly the solutions of the system, for almost periodic systems. The significance of the ideas and tools presented is illustrated by means of simple examples. Applications to model reduction from input-output data and stability analysis of skew-symmetric systems are also discussed.
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CDC - A geometric characterisation of the persistence of Excitation Condition for sequences generated by discrete-time autonomous systems
2016 IEEE 55th Conference on Decision and Control (CDC), 2016Co-Authors: Alberto Padoan, Giordano Scarciotti, Alessandro AstolfiAbstract:The persistence of Excitation Condition for sequences generated by discrete-time, time-invariant, autonomous linear and nonlinear systems is studied. A rank Condition is shown to be equivalent to the persistence of Excitation of sequences generated by the class of systems considered, consistently with the results established by the authors for the continuous-time case. The Condition is geometric in nature and can be checked a priori for a Poisson stable system, that is, without knowing explicitly the state trajectories of the system. The significance of the ideas and tools presented is illustrated by means of simple examples.
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A geometric characterisation of the persistence of Excitation Condition for sequences generated by discrete-time autonomous systems
2016 IEEE 55th Conference on Decision and Control (CDC), 2016Co-Authors: Alberto Padoan, Giordano Scarciotti, Alessandro AstolfiAbstract:The persistence of Excitation Condition for sequences generated by discrete-time, time-invariant, autonomous linear and nonlinear systems is studied. A rank Condition is shown to be equivalent to the persistence of Excitation of sequences generated by the class of systems considered, consistently with the results established by the authors for the continuous-time case. The Condition is geometric in nature and can be checked a priori for a Poisson stable system, that is, without knowing explicitly the state trajectories of the system. The significance of the ideas and tools presented is illustrated by means of simple examples.
Alberto Padoan - One of the best experts on this subject based on the ideXlab platform.
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A Geometric Characterization of the Persistence of Excitation Condition for the Solutions of Autonomous Systems
IEEE Transactions on Automatic Control, 2017Co-Authors: Alberto Padoan, Giordano Scarciotti, Alessandro AstolfiAbstract:The persistence of Excitation of signals generated by time-invariant, autonomous, linear, and nonlinear systems is studied using a geometric approach. A rank Condition is shown to be equivalent, under certain assumptions, to the persistence of Excitation of the solutions of the class of systems considered, both in the discrete-time and in the continuous-time settings. The rank Condition is geometric in nature and can be checked a priori, i.e. without knowing explicitly the solutions of the system, for almost periodic systems. The significance of the ideas and tools presented is illustrated by means of simple examples. Applications to model reduction from input-output data and stability analysis of skew-symmetric systems are also discussed.
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CDC - A geometric characterisation of the persistence of Excitation Condition for sequences generated by discrete-time autonomous systems
2016 IEEE 55th Conference on Decision and Control (CDC), 2016Co-Authors: Alberto Padoan, Giordano Scarciotti, Alessandro AstolfiAbstract:The persistence of Excitation Condition for sequences generated by discrete-time, time-invariant, autonomous linear and nonlinear systems is studied. A rank Condition is shown to be equivalent to the persistence of Excitation of sequences generated by the class of systems considered, consistently with the results established by the authors for the continuous-time case. The Condition is geometric in nature and can be checked a priori for a Poisson stable system, that is, without knowing explicitly the state trajectories of the system. The significance of the ideas and tools presented is illustrated by means of simple examples.
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A geometric characterisation of the persistence of Excitation Condition for sequences generated by discrete-time autonomous systems
2016 IEEE 55th Conference on Decision and Control (CDC), 2016Co-Authors: Alberto Padoan, Giordano Scarciotti, Alessandro AstolfiAbstract:The persistence of Excitation Condition for sequences generated by discrete-time, time-invariant, autonomous linear and nonlinear systems is studied. A rank Condition is shown to be equivalent to the persistence of Excitation of sequences generated by the class of systems considered, consistently with the results established by the authors for the continuous-time case. The Condition is geometric in nature and can be checked a priori for a Poisson stable system, that is, without knowing explicitly the state trajectories of the system. The significance of the ideas and tools presented is illustrated by means of simple examples.
Xiuli Wang - One of the best experts on this subject based on the ideXlab platform.
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trap states and carrier dynamics of tio2 studied by photoluminescence spectroscopy under weak Excitation Condition
Physical Chemistry Chemical Physics, 2010Co-Authors: Xiuli Wang, Zhaochi Feng, Shuai Shen, Jun Zhou, Can LiAbstract:Anatase and rutile TiO2 were investigated with photoluminescence techniques under the weak Excitation Condition, where trap states play a vital role in carrier dynamics. The visible emission of anatase and near-infrared (NIR) emission of rutile both exhibit extremely long lifetimes up to milliseconds. The decay processes can be well described by the power-law decay which corresponds to the trapping–detrapping effect. These results indicate that the luminescence processes in both anatase and rutile TiO2 have a close relationship with trap states. The visible emission band was assigned to the donor–acceptor recombination. Oxygen vacancies and hydroxyl groups mainly serve as the donor and acceptor sites, respectively. The NIR luminescence is originated from the recombination of trapped electrons with free holes, while the trapped electrons were formed through two paths, direct trapping or trap-to-trap hopping. The trap states in anatase and rutile TiO2 may largely influence the photocatalysis process of TiO2 and determine the photocatalytic activity under stationary illumination.
Raymond A. De Callafon - One of the best experts on this subject based on the ideXlab platform.
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CDC - Persistent Excitation Condition for MIMO Volterra System Identification with Gaussian Distributed Input Signals
2019 IEEE 58th Conference on Decision and Control (CDC), 2019Co-Authors: Yangsheng Hu, Raymond A. De CallafonAbstract:A viable approach to the estimation and char-acterization of non-linear system dynamics on the basis of input/ouput observations of a non-linear system is a parametrization based on a Volterra model. The kernel representation of a Volterra model can approximate a large class of non-linear systems and has the advantage of being linear in the kernel parameters to be estimated. Although the number of kernel parameters typically increases exponentially, the demand for storage requirements during kernel parameter estimation can be relieved via a tensor network technique. This approach allows estimation of high degree and even multi-input multi-output (MIMO) Volterra models, which have the potential to capture more complicated non-linear dynamics. This paper gives a persistent Excitation Condition for the parameter estimation in MIMO Volterra system identification in the case of a zero mean, Gaussian distributed (not necessarily white) input signal. The persistent Excitation Condition shows that under those input Conditions a MIMO Volterra system can be identified consistently via an appropriately sized input signal.
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Persistent Excitation Condition for MIMO Volterra System Identification with Gaussian Distributed Input Signals
2019 IEEE 58th Conference on Decision and Control (CDC), 2019Co-Authors: Yangsheng Hu, Raymond A. De CallafonAbstract:A viable approach to the estimation and char-acterization of non-linear system dynamics on the basis of input/ouput observations of a non-linear system is a parametrization based on a Volterra model. The kernel representation of a Volterra model can approximate a large class of non-linear systems and has the advantage of being linear in the kernel parameters to be estimated. Although the number of kernel parameters typically increases exponentially, the demand for storage requirements during kernel parameter estimation can be relieved via a tensor network technique. This approach allows estimation of high degree and even multi-input multi-output (MIMO) Volterra models, which have the potential to capture more complicated non-linear dynamics. This paper gives a persistent Excitation Condition for the parameter estimation in MIMO Volterra system identification in the case of a zero mean, Gaussian distributed (not necessarily white) input signal. The persistent Excitation Condition shows that under those input Conditions a MIMO Volterra system can be identified consistently via an appropriately sized input signal.
Li Liang - One of the best experts on this subject based on the ideXlab platform.
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color modulation and temperature sensing investigation of gd2o3 1 mol er3 1 mol yb3 phosphors under different Excitation Condition
Journal of Luminescence, 2019Co-Authors: Xueru Zhang, Yuxiao Wang, Li LiangAbstract:Abstract Recently, modulating emission color and increasing temperature sensing sensitivity of rare earth doped materials are imperative because of their applications in colorful display, multiplexed labeling and temperature sensing. In this work, the emission color, radiated from Gd2O3: 1 mol% Er3+/1 mol% Yb3+ phosphors, is modulated through co-Excitation Condition, which is attributed to the additional co-excited up-conversion processes. The validity of co-excited up-conversion processes are demonstrated via the multi-photon up-conversion processes. More importantly, the temperature-dependent green emissions from Gd2O3: 1 mol%Er3+/1 mol%Yb3+ phosphors under different Excitation Condition are investigated. The fluorescence intensity ratio (FIR) of 522 and 562 nm (R522/562) exhibits relatively high sensing sensitivities among that of R522/538, R522/553, R522/562 due to the big energy gap. The maximal sensing sensibility (4.1 %K−1) is obtained as the sample is co-excited under 980 and 1550 nm lasers, which is 37% improvement over single 980 nm laser Excitation (3.0 %K−1). The results confirm that the co-excited method is promising to serve as an alternative approach for tuning the emission color and enhancing the temperature sensing sensibility of up-conversion materials.
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Color modulation and temperature sensing investigation of Gd2O3: 1 mol% Er3+, 1 mol% Yb3+ phosphors under different Excitation Condition
Journal of Luminescence, 2019Co-Authors: Xueru Zhang, Yuxiao Wang, Li LiangAbstract:Abstract Recently, modulating emission color and increasing temperature sensing sensitivity of rare earth doped materials are imperative because of their important applications in colorful display, multiplexed labeling and temperature sensing. In this work, the emission color, radiated from Gd 2 O 3 : 1 mol% Er 3+ /1 mol% Yb 3+ phosphors, is observed to be strongly dependent on Excitation Condition, which is attributed to the additional co-excited up-conversion processes. Meanwhile, the validity of co-excited up-conversion processes are demonstrated through the multi-photon up-conversion processes. More importantly, the temperature-dependent green emissions of Gd 2 O 3 : 1 mol% Er 3+ /1 mol% Yb 3+ phosphors under different Excitation Condition are investigated and the fluorescence intensity ratio (FIR) of 522 and 562 nm ( R 522/562 ) exhibits relatively high sensing sensitivities among that of R 522/538 , R 522/553 , R 522/562 due to their big energy gap. The maximal sensing sensibility (4.1 %K −1 ) is obtained as the sample is co-excited under 980 and 1550 nm lasers, which is 37% improvement over single 980 nm laser Excitation (3.0 %K −1 ). In addition, the obvious variation in emission color with the temperature increase is observed, especially when the sample is excited with 1550 nm laser or co-excited with 980 and 1550 nm laser. The results confirm that the co-excited method is promising to serve as an alternative approach for tuning the emission color and enhancing the temperature sensing sensibility of up-conversion materials.
