The Experts below are selected from a list of 12189 Experts worldwide ranked by ideXlab platform

Simon Nehr - One of the best experts on this subject based on the ideXlab platform.

  • Radiation Resistant Fiber Bragg grating in random air-line Fibers for sensing applications in nuclear reactor cores
    Optics Express, 2018
    Co-Authors: Mohamed A.s. Zaghloul, Mohan Wang, Sheng Huang, Cyril Hnatovsky, Dan Grobnic, Stephen Mihailov, David Carpenter, Joshua Daw, Guillaume Laffont, Simon Nehr
    Abstract:

    This paper reports the testing results of radiation Resistant Fiber Bragg grating (FBG) in random air-line (RAL) Fibers in comparison with FBGs in other radiation-hardened Fibers. FBGs in RAL Fibers were fabricated by 80 fs ultrafast laser pulse using a phase mask approach. The Fiber Bragg gratings tests were carried out in the core region of a 6 MW MIT research reactor (MITR) at a steady temperature above 600°C and an average fast neutron (>1 MeV) flux >1.2 × 10$^{14}$ n/cm$^2$/s. Fifty five-day tests of FBG sensors showed less than 5 dB reduction in FBG peak strength after over 1 × 10$^{20}$ n/cm$^2$ of accumulated fast neutron dose. The radiation-induced compaction of FBG sensors produced less than 5.5 nm FBG wavelength shift toward shorter wavelength. To test temporal responses of FBG sensors, a number of reactor anomaly events were artificially created to abruptly change reactor power, temperature, and neutron flux over short periods of time. The thermal sensitivity and temporal responses of FBGs were determined at different accumulated doses of neutron flux. Results presented in this paper reveal that temperature-stable Type-II FBGs fabricated in radiation-hardened Fibers can survive harsh in-pile conditions. Despite large parameter drift induced by strong nuclear radiation, further engineering and innovation on both optical Fibers and Fiber devices could lead to useful Fiber sensors for various in-pile measurements to improve safety and efficiency of existing and next generation nuclear reactors.

Ole Bang - One of the best experts on this subject based on the ideXlab platform.

Mohamed A.s. Zaghloul - One of the best experts on this subject based on the ideXlab platform.

  • Radiation Resistant Fiber Bragg grating in random air-line Fibers for sensing applications in nuclear reactor cores
    Optics Express, 2018
    Co-Authors: Mohamed A.s. Zaghloul, Mohan Wang, Sheng Huang, Cyril Hnatovsky, Dan Grobnic, Stephen Mihailov, David Carpenter, Joshua Daw, Guillaume Laffont, Simon Nehr
    Abstract:

    This paper reports the testing results of radiation Resistant Fiber Bragg grating (FBG) in random air-line (RAL) Fibers in comparison with FBGs in other radiation-hardened Fibers. FBGs in RAL Fibers were fabricated by 80 fs ultrafast laser pulse using a phase mask approach. The Fiber Bragg gratings tests were carried out in the core region of a 6 MW MIT research reactor (MITR) at a steady temperature above 600°C and an average fast neutron (>1 MeV) flux >1.2 × 10$^{14}$ n/cm$^2$/s. Fifty five-day tests of FBG sensors showed less than 5 dB reduction in FBG peak strength after over 1 × 10$^{20}$ n/cm$^2$ of accumulated fast neutron dose. The radiation-induced compaction of FBG sensors produced less than 5.5 nm FBG wavelength shift toward shorter wavelength. To test temporal responses of FBG sensors, a number of reactor anomaly events were artificially created to abruptly change reactor power, temperature, and neutron flux over short periods of time. The thermal sensitivity and temporal responses of FBGs were determined at different accumulated doses of neutron flux. Results presented in this paper reveal that temperature-stable Type-II FBGs fabricated in radiation-hardened Fibers can survive harsh in-pile conditions. Despite large parameter drift induced by strong nuclear radiation, further engineering and innovation on both optical Fibers and Fiber devices could lead to useful Fiber sensors for various in-pile measurements to improve safety and efficiency of existing and next generation nuclear reactors.

Yoji Okabe - One of the best experts on this subject based on the ideXlab platform.

  • an ultrasonic visualization system using a Fiber optic bragg grating sensor and its application to damage detection at a temperature of 1000 c
    Mechanical Systems and Signal Processing, 2021
    Co-Authors: Osamu Saito, Yoji Okabe
    Abstract:

    Abstract Structural health monitoring (SHM) techniques are required to evaluate the reliability of aging heat-Resistant structures. To build a method of high-temperature in situ damage diagnosis, the authors developed a laser ultrasonic visualization system with a heat-Resistant Fiber-optic Bragg grating (FBG) sensing configuration. In this system, an ultrasonic wave is excited by laser irradiation on the surface of a material and then received by a remotely installed FBG sensor. Because both the wave excitation and wave sensing parts have excellent heat resistance, the proposed sensing system enables a stable ultrasonic measurement at a temperature of 1000 °C. In this research, a wavenumber-frequency analysis shows that the proposed sensing system was able to visualize the correct laser ultrasonic wavefield in a planar structure. The ultrasonic visualization performance was then verified for a plate of heat-Resistant material at temperatures of 200 and 1000 °C. A wavenumber-frequency analysis based on a three-dimensional Fourier transform was also conducted to extract the wave components corresponding to the reflection caused by an artificial defect in the plate. As a result, the developed method enabled clear damage identification at temperatures as high as 1000 °C.

Antonio Nanni - One of the best experts on this subject based on the ideXlab platform.

  • Fiber reinforced cement based composite system for concrete confinement
    Construction and Building Materials, 2012
    Co-Authors: Francisco De Caso Y Basalo, Fabio Matta, Antonio Nanni
    Abstract:

    Abstract This paper reports on a feasibility study to develop a reversible and potentially fire-Resistant Fiber reinforced cement-based matrix (FRC) composite system for concrete confinement applications. The first part of this study aimed at selecting a candidate FRC system from different Fiber (including glass and basalt) and inorganic matrix combinations on the basis of: constructability, by verifying the workability and ease of installation on concrete cylinders; structural performance, by evaluating strength and deformability enhancement in confined concrete cylinders tested under uniaxial compression; and compatibility, by examining the quality of the concrete–FRC interface and the level of Fiber impregnation using scanning electron microscope images. In the second part of this study, the selected FRC system was further assessed through compression tests of additional concrete cylinders confined using different FRC reinforcement ratios, where both axial and in-plane (radial) deformations were measured to assess confinement effectiveness. The feasibility of making the application reversible was investigated by introducing a bond breaker between the concrete substrate and the composite jacket in a series of confined cylinders. The prototype FRC system produced a substantial increase in strength and deformability with respect to unconfined cylinders. A superior deformability was attained without the use of a bond breaker. The predominant failure mode was loss of compatibility due to Fiber–matrix separation, which points to the need of improving Fiber impregnation to enable a more efficient use of the constituent materials. Semi-empirical linear and nonlinear models for compressive strength and deformation in FRC-confined concrete are also presented.