The Experts below are selected from a list of 6825 Experts worldwide ranked by ideXlab platform

T. H. T. Chan - One of the best experts on this subject based on the ideXlab platform.

  • vertical displacement measurements for bridges using optical fiber sensors and CCD Cameras a preliminary study
    Structural Health Monitoring-an International Journal, 2009
    Co-Authors: T. H. T. Chan, D. B. Ashebo, P.c. Lee, Hwa-yaw Tam, T F Chan, Eduardo Perez Gracia
    Abstract:

    Bridge managers all over the world are always looking for simple ways to measure bridge vertical displacements for structural health monitoring. However, traditional methods to obtain such data are either tedious or expensive. There is a need to develop a simple, inexpensive, and yet practical method to measure bridge vertical displacements. This paper proposes two methods using either optical fiber (FBG) sensors or a charge-coupled-device (CCD) camera, respectively, for vertical displacement measurements of bridges. The FBG sensor method is based on the measured horizontal strains together with the identified curvature functions obtained by a self-developed FBG Tilt sensor. CCD Cameras use a large number of pixels to form an image. The CCD camera method utilizes image processing techniques for pixel identification and subsequent edge detection. A preliminary study to validate the proposed methods in laboratory was presented. The tests include applying the methods to determine the vertical displacements s...

  • Vertical Displacement Measurements for Bridges Using Optical Fiber Sensors and CCD Cameras -- A Preliminary Study
    Structural Health Monitoring, 2009
    Co-Authors: T. H. T. Chan, D. B. Ashebo, P.c. Lee, Hwa-yaw Tam, T F Chan, Esther Pérez-gracia
    Abstract:

    Bridge managers all over the world are always looking for simple ways to measure bridge vertical displacements for structural health monitoring. However, traditional methods to obtain such data are either tedious or expensive. There is a need to develop a simple, inexpensive, and yet practical method to measure bridge vertical displacements. This paper proposes two methods using either optical fiber (FBG) sensors or a charge-coupled-device (CCD) camera, respectively, for vertical displacement measurements of bridges. The FBG sensor method is based on the measured horizontal strains together with the identified curvature functions obtained by a self-developed FBG Tilt sensor. CCD Cameras use a large number of pixels to form an image. The CCD camera method utilizes image processing techniques for pixel identification and subsequent edge detection. A preliminary study to validate the proposed methods in laboratory was presented. The tests include applying the methods to determine the vertical displacements separately for a concrete beam and a steel beam under various loadings. The comparisons include their installations, costs, degrees of accuracy, external factors affecting the measurement, etc. It was concluded that both methods could be used for vertical displacement measurement, and they could be complementary with one another. It was suggested to further improve the two methods developed and a successful outcome will not only help to solve an important problem for bridge management, but also prepare the way for better structural health monitoring techniques.

M V Chekhova - One of the best experts on this subject based on the ideXlab platform.

  • optical coherence tomography with a nonlinear interferometer in the high parametric gain regime
    Applied Physics Letters, 2020
    Co-Authors: Gerard J Machado, Gaetano Frascella, Juan P Torres, M V Chekhova
    Abstract:

    We demonstrate optical coherence tomography based on an SU(1,1) nonlinear interferometer with high-gain parametric downconversion. For imaging and sensing applications, this scheme promises to outperform previous experiments working at low parametric gain, since higher photon fluxes provide lower integration times for obtaining high-quality images. In this way, one can avoid using single-photon detectors or CCD Cameras with very high sensitivities, and standard spectrometers can be used instead. Other advantages are higher sensitivity to small loss and amplification before detection so that the detected light power considerably exceeds the probing one.

Esther Pérez-gracia - One of the best experts on this subject based on the ideXlab platform.

  • Vertical Displacement Measurements for Bridges Using Optical Fiber Sensors and CCD Cameras -- A Preliminary Study
    Structural Health Monitoring, 2009
    Co-Authors: T. H. T. Chan, D. B. Ashebo, P.c. Lee, Hwa-yaw Tam, T F Chan, Esther Pérez-gracia
    Abstract:

    Bridge managers all over the world are always looking for simple ways to measure bridge vertical displacements for structural health monitoring. However, traditional methods to obtain such data are either tedious or expensive. There is a need to develop a simple, inexpensive, and yet practical method to measure bridge vertical displacements. This paper proposes two methods using either optical fiber (FBG) sensors or a charge-coupled-device (CCD) camera, respectively, for vertical displacement measurements of bridges. The FBG sensor method is based on the measured horizontal strains together with the identified curvature functions obtained by a self-developed FBG Tilt sensor. CCD Cameras use a large number of pixels to form an image. The CCD camera method utilizes image processing techniques for pixel identification and subsequent edge detection. A preliminary study to validate the proposed methods in laboratory was presented. The tests include applying the methods to determine the vertical displacements separately for a concrete beam and a steel beam under various loadings. The comparisons include their installations, costs, degrees of accuracy, external factors affecting the measurement, etc. It was concluded that both methods could be used for vertical displacement measurement, and they could be complementary with one another. It was suggested to further improve the two methods developed and a successful outcome will not only help to solve an important problem for bridge management, but also prepare the way for better structural health monitoring techniques.

Eduardo Perez Gracia - One of the best experts on this subject based on the ideXlab platform.

  • vertical displacement measurements for bridges using optical fiber sensors and CCD Cameras a preliminary study
    Structural Health Monitoring-an International Journal, 2009
    Co-Authors: T. H. T. Chan, D. B. Ashebo, P.c. Lee, Hwa-yaw Tam, T F Chan, Eduardo Perez Gracia
    Abstract:

    Bridge managers all over the world are always looking for simple ways to measure bridge vertical displacements for structural health monitoring. However, traditional methods to obtain such data are either tedious or expensive. There is a need to develop a simple, inexpensive, and yet practical method to measure bridge vertical displacements. This paper proposes two methods using either optical fiber (FBG) sensors or a charge-coupled-device (CCD) camera, respectively, for vertical displacement measurements of bridges. The FBG sensor method is based on the measured horizontal strains together with the identified curvature functions obtained by a self-developed FBG Tilt sensor. CCD Cameras use a large number of pixels to form an image. The CCD camera method utilizes image processing techniques for pixel identification and subsequent edge detection. A preliminary study to validate the proposed methods in laboratory was presented. The tests include applying the methods to determine the vertical displacements s...

D. B. Ashebo - One of the best experts on this subject based on the ideXlab platform.

  • vertical displacement measurements for bridges using optical fiber sensors and CCD Cameras a preliminary study
    Structural Health Monitoring-an International Journal, 2009
    Co-Authors: T. H. T. Chan, D. B. Ashebo, P.c. Lee, Hwa-yaw Tam, T F Chan, Eduardo Perez Gracia
    Abstract:

    Bridge managers all over the world are always looking for simple ways to measure bridge vertical displacements for structural health monitoring. However, traditional methods to obtain such data are either tedious or expensive. There is a need to develop a simple, inexpensive, and yet practical method to measure bridge vertical displacements. This paper proposes two methods using either optical fiber (FBG) sensors or a charge-coupled-device (CCD) camera, respectively, for vertical displacement measurements of bridges. The FBG sensor method is based on the measured horizontal strains together with the identified curvature functions obtained by a self-developed FBG Tilt sensor. CCD Cameras use a large number of pixels to form an image. The CCD camera method utilizes image processing techniques for pixel identification and subsequent edge detection. A preliminary study to validate the proposed methods in laboratory was presented. The tests include applying the methods to determine the vertical displacements s...

  • Vertical Displacement Measurements for Bridges Using Optical Fiber Sensors and CCD Cameras -- A Preliminary Study
    Structural Health Monitoring, 2009
    Co-Authors: T. H. T. Chan, D. B. Ashebo, P.c. Lee, Hwa-yaw Tam, T F Chan, Esther Pérez-gracia
    Abstract:

    Bridge managers all over the world are always looking for simple ways to measure bridge vertical displacements for structural health monitoring. However, traditional methods to obtain such data are either tedious or expensive. There is a need to develop a simple, inexpensive, and yet practical method to measure bridge vertical displacements. This paper proposes two methods using either optical fiber (FBG) sensors or a charge-coupled-device (CCD) camera, respectively, for vertical displacement measurements of bridges. The FBG sensor method is based on the measured horizontal strains together with the identified curvature functions obtained by a self-developed FBG Tilt sensor. CCD Cameras use a large number of pixels to form an image. The CCD camera method utilizes image processing techniques for pixel identification and subsequent edge detection. A preliminary study to validate the proposed methods in laboratory was presented. The tests include applying the methods to determine the vertical displacements separately for a concrete beam and a steel beam under various loadings. The comparisons include their installations, costs, degrees of accuracy, external factors affecting the measurement, etc. It was concluded that both methods could be used for vertical displacement measurement, and they could be complementary with one another. It was suggested to further improve the two methods developed and a successful outcome will not only help to solve an important problem for bridge management, but also prepare the way for better structural health monitoring techniques.