The Experts below are selected from a list of 1999911 Experts worldwide ranked by ideXlab platform

Xiaodong Wang - One of the best experts on this subject based on the ideXlab platform.

  • Low-Complexity Quickest Change Detection in Linear Systems with Unknown Time-Varying Pre-and Post-Change Distributions
    IEEE Transactions on Information Theory, 2026
    Co-Authors: Jiangfan Zhang, Xiaodong Wang
    Abstract:

    Motivated by the sequential detection of false data injection attacks (FDIAs) in a dynamic smart grid, we consider a more general problem of sequentially detecting a Time-Varying Change in a dynamic linear regression model. To be specific, when the Change occurs, a Time-Varying unknown vector is added in the linear regression model. The parameter vector of the linear regression model is also assumed to be unknown and Time-Varying. Thus, the pre- and post-Change distributions are both unknown and Time-Varying. This imposes a significant challenge for designing a computationally efficient sequential detector. We first propose two Cumulative-Sum-type algorithms to address this challenge. One is called generalized Cumulative-Sum (GCUSUM) algorithm, and the other one is called relaxed generalized Cumulative-Sum (RGCUSUM) algorithm, which is a modified version of the GCUSUM. It can be shown that the computational complexity of the proposed RGCUSUM algorithm scales linearly with the number of observations. Next, considering Lordon’s setup, for any given constraint on the expected false alarm period, a lower bound on the threshold employed in the proposed RGCUSUM algorithm is derived, which provides a useful guideline for the design of the proposed RGCUSUM algorithm to achieve any prescribed performance requirement in practice. In addition, for any given threshold employed in the proposed RGCUSUM algorithm, an upper bound on the expected detection delay is also provided. The performance of the proposed RGCUSUM algorithm is numerically studied in the context of an IEEE standard power system under FDIAs. Moreover, the numerical results demonstrate the superiority of the proposed RGCUSUM in computational efficiency.

Jiangfan Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Low-Complexity Quickest Change Detection in Linear Systems with Unknown Time-Varying Pre-and Post-Change Distributions
    IEEE Transactions on Information Theory, 2026
    Co-Authors: Jiangfan Zhang, Xiaodong Wang
    Abstract:

    Motivated by the sequential detection of false data injection attacks (FDIAs) in a dynamic smart grid, we consider a more general problem of sequentially detecting a Time-Varying Change in a dynamic linear regression model. To be specific, when the Change occurs, a Time-Varying unknown vector is added in the linear regression model. The parameter vector of the linear regression model is also assumed to be unknown and Time-Varying. Thus, the pre- and post-Change distributions are both unknown and Time-Varying. This imposes a significant challenge for designing a computationally efficient sequential detector. We first propose two Cumulative-Sum-type algorithms to address this challenge. One is called generalized Cumulative-Sum (GCUSUM) algorithm, and the other one is called relaxed generalized Cumulative-Sum (RGCUSUM) algorithm, which is a modified version of the GCUSUM. It can be shown that the computational complexity of the proposed RGCUSUM algorithm scales linearly with the number of observations. Next, considering Lordon’s setup, for any given constraint on the expected false alarm period, a lower bound on the threshold employed in the proposed RGCUSUM algorithm is derived, which provides a useful guideline for the design of the proposed RGCUSUM algorithm to achieve any prescribed performance requirement in practice. In addition, for any given threshold employed in the proposed RGCUSUM algorithm, an upper bound on the expected detection delay is also provided. The performance of the proposed RGCUSUM algorithm is numerically studied in the context of an IEEE standard power system under FDIAs. Moreover, the numerical results demonstrate the superiority of the proposed RGCUSUM in computational efficiency.

Dhesi Sarnjeet - One of the best experts on this subject based on the ideXlab platform.

  • Ultrafast time-evolution of chiral N\'eel magnetic domain walls probed by circular dichroism in x-ray resonant magnetic scattering
    2021
    Co-Authors: Léveillé Cyril, Burgos-parra Erick, Sassi Yanis, Ajejas Fernando, Chardonnet Valentin, Pedersoli Emanuele, Capotondi Flavio, De Ninno Giovanni, Maccherozzi Francesco, Dhesi Sarnjeet
    Abstract:

    Non-collinear spin textures in ferromagnetic ultrathin films are attracting a renewed interest fueled by possible fine engineering of several magnetic interactions, notably the interfacial Dzyaloshinskii-Moriya interaction. This allows the stabilization of complex chiral spin textures such as chiral magnetic domain walls (DWs), spin spirals, and magnetic skyrmions. We report here on the ultrafast behavior of chiral DWs after optical pumping in perpendicularly magnetized asymmetric multilayers, probed using time-resolved circular dichroism in x-ray resonant magnetic scattering (CD-XRMS). We observe a picosecond transient reduction of the CD-XRMS, which is attributed to the spin current-induced coherent and incoherent torques within the continuously dependent spin texture of the DWs. We argue that a specific demagnetization of the inner structure of the DW induces a flow of hot spins from the interior of the neighboring magnetic domains. We identify this Time-Varying Change of the DW textures shortly after the laser pulse as a distortion of the homochiral N'eel shape toward a transient mixed Bloch-N\'eel-Bloch textures along a direction transverse to the DW. Our study highlights how time-resolved CD-XRMS can be a unique tool for studying the time evolution in other systems showing a non-collinear electric/magnetic ordering such as skyrmion lattices, conical/helical phases, as well as the recently observed antiskyrmion lattices, in metallic or insulating materials

Léveillé Cyril - One of the best experts on this subject based on the ideXlab platform.

  • Ultrafast time-evolution of chiral N\'eel magnetic domain walls probed by circular dichroism in x-ray resonant magnetic scattering
    2021
    Co-Authors: Léveillé Cyril, Burgos-parra Erick, Sassi Yanis, Ajejas Fernando, Chardonnet Valentin, Pedersoli Emanuele, Capotondi Flavio, De Ninno Giovanni, Maccherozzi Francesco, Dhesi Sarnjeet
    Abstract:

    Non-collinear spin textures in ferromagnetic ultrathin films are attracting a renewed interest fueled by possible fine engineering of several magnetic interactions, notably the interfacial Dzyaloshinskii-Moriya interaction. This allows the stabilization of complex chiral spin textures such as chiral magnetic domain walls (DWs), spin spirals, and magnetic skyrmions. We report here on the ultrafast behavior of chiral DWs after optical pumping in perpendicularly magnetized asymmetric multilayers, probed using time-resolved circular dichroism in x-ray resonant magnetic scattering (CD-XRMS). We observe a picosecond transient reduction of the CD-XRMS, which is attributed to the spin current-induced coherent and incoherent torques within the continuously dependent spin texture of the DWs. We argue that a specific demagnetization of the inner structure of the DW induces a flow of hot spins from the interior of the neighboring magnetic domains. We identify this Time-Varying Change of the DW textures shortly after the laser pulse as a distortion of the homochiral N'eel shape toward a transient mixed Bloch-N\'eel-Bloch textures along a direction transverse to the DW. Our study highlights how time-resolved CD-XRMS can be a unique tool for studying the time evolution in other systems showing a non-collinear electric/magnetic ordering such as skyrmion lattices, conical/helical phases, as well as the recently observed antiskyrmion lattices, in metallic or insulating materials

Pedersoli Emanuele - One of the best experts on this subject based on the ideXlab platform.

  • Ultrafast time-evolution of chiral N\'eel magnetic domain walls probed by circular dichroism in x-ray resonant magnetic scattering
    2021
    Co-Authors: Léveillé Cyril, Burgos-parra Erick, Sassi Yanis, Ajejas Fernando, Chardonnet Valentin, Pedersoli Emanuele, Capotondi Flavio, De Ninno Giovanni, Maccherozzi Francesco, Dhesi Sarnjeet
    Abstract:

    Non-collinear spin textures in ferromagnetic ultrathin films are attracting a renewed interest fueled by possible fine engineering of several magnetic interactions, notably the interfacial Dzyaloshinskii-Moriya interaction. This allows the stabilization of complex chiral spin textures such as chiral magnetic domain walls (DWs), spin spirals, and magnetic skyrmions. We report here on the ultrafast behavior of chiral DWs after optical pumping in perpendicularly magnetized asymmetric multilayers, probed using time-resolved circular dichroism in x-ray resonant magnetic scattering (CD-XRMS). We observe a picosecond transient reduction of the CD-XRMS, which is attributed to the spin current-induced coherent and incoherent torques within the continuously dependent spin texture of the DWs. We argue that a specific demagnetization of the inner structure of the DW induces a flow of hot spins from the interior of the neighboring magnetic domains. We identify this Time-Varying Change of the DW textures shortly after the laser pulse as a distortion of the homochiral N'eel shape toward a transient mixed Bloch-N\'eel-Bloch textures along a direction transverse to the DW. Our study highlights how time-resolved CD-XRMS can be a unique tool for studying the time evolution in other systems showing a non-collinear electric/magnetic ordering such as skyrmion lattices, conical/helical phases, as well as the recently observed antiskyrmion lattices, in metallic or insulating materials