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Fiber Optic Sensors: Fundamentals and Applications

01 Aug 1988-
About: The article was published on 1988-08-01 and is currently open access. It has received 272 citations till now. The article focuses on the topics: Fiber optic sensor.
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Journal ArticleDOI
21 Feb 2019-Sensors
TL;DR: An overview of the currently available contact-based methods for measuring respiratory rate is provided, based upon the recording of respiratory airflow, sounds, air temperature, air humidity, air components, chest wall movements, and modulation of the cardiac activity.
Abstract: There is an ever-growing demand for measuring respiratory variables during a variety of applications, including monitoring in clinical and occupational settings, and during sporting activities and exercise. Special attention is devoted to the monitoring of respiratory rate because it is a vital sign, which responds to a variety of stressors. There are different methods for measuring respiratory rate, which can be classed as contact-based or contactless. The present paper provides an overview of the currently available contact-based methods for measuring respiratory rate. For these methods, the sensing element (or part of the instrument containing it) is attached to the subject’s body. Methods based upon the recording of respiratory airflow, sounds, air temperature, air humidity, air components, chest wall movements, and modulation of the cardiac activity are presented. Working principles, metrological characteristics, and applications in the respiratory monitoring field are presented to explore potential development and applicability for each method.

248 citations


Cites background from "Fiber Optic Sensors: Fundamentals a..."

  • ...This change may be expressed as follow [106]:...

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  • ...The response is linear, and its temperature sensitivity coefficient is a function of the operating wavelength and the material’s properties of the fiber in which the FBG is inscribed [106]....

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Patent
26 May 2005
TL;DR: In this paper, a fiber optic tether disposed in coiled tubing for communicating information between downhole tools and sensors and surface equipment and methods of operating such equipment is described, which includes transmitting control signals from the surface equipment to the downhole equipment over the fiber-optic tether, or collecting information by measuring an optical property observed on the fiber optic property.
Abstract: Apparatus having a fiber optic tether disposed in coiled tubing for communicating information between downhole tools and sensors and surface equipment and methods of operating such equipment. Wellbore operations performed using the fiber optic enabled coiled tubing apparatus includes transmitting control signals from the surface equipment to the downhole equipment over the fiber optic tether, transmitting information gathered from at least one downhole sensor to the surface equipment over the fiber optic tether, or collecting information by measuring an optical property observed on the fiber optic tether. The downhole tools or sensors connected to the fiber optic tether may either include devices that manipulate or respond to optical signal directly or tools or sensors that operate according to conventional principles.

203 citations

Journal ArticleDOI
TL;DR: In this article, a review of the main classes of silica-based optical fibers are presented: radiation tolerant pure-silica core or fluorine doped optical fibers, germanosilicate optical fibers and radiation sensitive phosphosilicates and aluminosa-ilimideal optical fibers.

195 citations

Patent
10 Aug 2011
TL;DR: In this paper, a dissolvable bridge plug configured with components for maintaining anchoring and structural integrity for high pressure applications is presented, where the plug is configured such that these components may substantially dissolve to allow for ease of plug removal following such applications.
Abstract: A dissolvable bridge plug configured with components for maintaining anchoring and structural integrity for high pressure applications. Embodiments of the plug are configured such that these components may substantially dissolve to allow for ease of plug removal following such applications. In one embodiment the plug may effectively provide isolation in a cased well for applications generating over about 8,000 - 10,000 psi. At the same time, by employment of a dissolve period for the noted components, such a plug may be drilled-out in less than about 30 minutes, even where, disposed in a lateral leg of the well.

192 citations

Journal ArticleDOI
TL;DR: The current state-of-the-art of fiber optic sensing/monitoring technologies, including the basic principles of various optical fiber sensors, novel sensing and computational methodologies, and practical applications for railway infrastructure monitoring are reviewed.
Abstract: In recent years, railway infrastructures and systems have played a significant role as a highly efficient transportation mode to meet the growing demand in transporting both cargo and passengers. Application of these structures in extreme environmental situation under severe working and loading conditions, caused by the traffic growth, heavier axles and vehicles and increase in speed makes it extremely susceptible to degradation and failure. In the last two decades, a significant number of innovative sensing technologies based on fiber optic sensors (FOS) have been utilized for structural health monitoring (SHM) due to their inherent distinctive advantages, such as small size, light weight, immunity to electromagnetic interference (EMI) and corrosion, and embedding capability. Fiber optic-based monitoring systems use quasi-distributed and continuously distributed sensing techniques for real time measurement and long term assessment of structural properties. This allows for early stage damage detection and characterization, leading to timely remediation and prevention of catastrophic failures. In this scenario, FOS have been proved to be a powerful tool for meticulous assessment of railway systems including train and track behavior by enabling real-time data collection, inspection and detection of structural degradation. This article reviews the current state-of-the-art of fiber optic sensing/monitoring technologies, including the basic principles of various optical fiber sensors, novel sensing and computational methodologies, and practical applications for railway infrastructure monitoring. Additionally, application of these technologies to monitor temperature, stresses, displacements, strain measurements, train speed, mass and location, axle counting, wheel imperfections, rail settlements, wear and tear and health assessment of railway bridges and tunnels will be thoroughly discussed.

117 citations