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Sergi Villalba

Bio: Sergi Villalba is an academic researcher from Polytechnic University of Catalonia. The author has contributed to research in topics: Structural health monitoring & Optical fiber. The author has an hindex of 9, co-authored 16 publications receiving 738 citations.

Papers
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Journal ArticleDOI
23 May 2016-Sensors
TL;DR: The latest developments related with the improvement of these products are presented by presenting a wide range of laboratory experiments as well as an extended review of their diverse applications in civil engineering structures.
Abstract: The application of structural health monitoring (SHM) systems to civil engineering structures has been a developing studied and practiced topic, that has allowed for a better understanding of structures’ conditions and increasingly lead to a more cost-effective management of those infrastructures In this field, the use of fiber optic sensors has been studied, discussed and practiced with encouraging results The possibility of understanding and monitor the distributed behavior of extensive stretches of critical structures it’s an enormous advantage that distributed fiber optic sensing provides to SHM systems In the past decade, several R & D studies have been performed with the goal of improving the knowledge and developing new techniques associated with the application of distributed optical fiber sensors (DOFS) in order to widen the range of applications of these sensors and also to obtain more correct and reliable data This paper presents, after a brief introduction to the theoretical background of DOFS, the latest developments related with the improvement of these products by presenting a wide range of laboratory experiments as well as an extended review of their diverse applications in civil engineering structures

572 citations

Journal ArticleDOI
TL;DR: The use of optical backscatter reflectometer (OBR) sensors is a promising measurement technology for Structural Health Monitoring (SHM) as it offers the possibility of continuous monitoring of strain and temperature along the fiber.

148 citations

Journal ArticleDOI
26 Mar 2018-Sensors
TL;DR: The results show the feasibility of using a thin coated polyimide DOFS directly bonded on the reinforcing bar without the need of indention or mechanization and a proposal for a Spectral Shift Quality (SSQ) threshold is obtained.
Abstract: When using distributed optical fiber sensors (DOFS) on reinforced concrete structures, a compromise must be achieved between the protection requirements and robustness of the sensor deployment and the accuracy of the measurements both in the uncracked and cracked stages and under loading, unloading and reloading processes. With this in mind the authors have carried out an experiment where polyimide-coated DOFS were installed on two concrete beams, both embedded in the rebar elements and also bonded to the concrete surface. The specimens were subjected to a three-point load test where after cracking, they are unloaded and reloaded again to assess the capability of the sensor when applied to a real loading scenarios in concrete structures. Rayleigh Optical Frequency Domain Reflectometry (OFDR) was used as the most suitable technique for crack detection in reinforced concrete elements. To verify the reliability and accuracy of the DOFS measurements, additional strain gauges were also installed at three locations along the rebar. The results show the feasibility of using a thin coated polyimide DOFS directly bonded on the reinforcing bar without the need of indention or mechanization. A proposal for a Spectral Shift Quality (SSQ) threshold is also obtained and proposed for future works when using polyimide-coated DOFS bonded to rebars with cyanoacrylate adhesive.

85 citations

Journal ArticleDOI
TL;DR: The main SHM results of the rehabilitation of an historical building used as hospital and the enlargement of a pre-stressed concrete bridge are presented using a novel DOFS based on an Optical Backscattered Reflectometry (OBR) technique.
Abstract: This is an Accepted Manuscript of an article published by Taylor & Francis Group in Structure and Infrastructure Engineering on 2018, available online at: http://www.tandfonline.com/10.1080/15732479.2018.1438479

67 citations

Journal ArticleDOI
TL;DR: In this paper, a Distributed Optical Fiber Sensor System (DOFS) was installed in the TMB L-9 metro tunnel in Barcelona for Structural Health Monitoring (SHM) purposes as the former could potentially be affected by the construction of a nearby residential building.

57 citations


Cited by
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Journal ArticleDOI
23 May 2016-Sensors
TL;DR: The latest developments related with the improvement of these products are presented by presenting a wide range of laboratory experiments as well as an extended review of their diverse applications in civil engineering structures.
Abstract: The application of structural health monitoring (SHM) systems to civil engineering structures has been a developing studied and practiced topic, that has allowed for a better understanding of structures’ conditions and increasingly lead to a more cost-effective management of those infrastructures In this field, the use of fiber optic sensors has been studied, discussed and practiced with encouraging results The possibility of understanding and monitor the distributed behavior of extensive stretches of critical structures it’s an enormous advantage that distributed fiber optic sensing provides to SHM systems In the past decade, several R & D studies have been performed with the goal of improving the knowledge and developing new techniques associated with the application of distributed optical fiber sensors (DOFS) in order to widen the range of applications of these sensors and also to obtain more correct and reliable data This paper presents, after a brief introduction to the theoretical background of DOFS, the latest developments related with the improvement of these products by presenting a wide range of laboratory experiments as well as an extended review of their diverse applications in civil engineering structures

572 citations

Journal ArticleDOI
TL;DR: Apart from the traditional composites for wind turbine blades, natural composites, hybrid and nanoengineered composites are discussed and their testing and modelling approaches are reviewed.
Abstract: A short overview of composite materials for wind turbine applications is presented here. Requirements toward the wind turbine materials, loads, as well as available materials are reviewed. Apart from the traditional composites for wind turbine blades (glass fibers/epoxy matrix composites), natural composites, hybrid and nanoengineered composites are discussed. Manufacturing technologies for wind turbine composites, as well their testing and modelling approaches are reviewed.

366 citations

01 Jan 1995
TL;DR: In this article, the authors present an analysis of the weakly-guiding fibers with step index profiles and their effect on wave propagation in the context of sourceless media, and the results show that these properties can be used to predict the wave propagation properties.
Abstract: Preface.Introduction.Chapter 1. Selected Topics in Electromagnetic Wave Propagation.1.1. Maxwell's Equations and the Fundamental Fields.1.2. Electromagnetic Wave Propagation in Sourceless Media.1.3. Power Transmission.1.4. Group Velocity.1.5. Reflection and Transmission of Waves at Plane Interfaces.1.6. Material Resonances and Their Effects on Wave Propagation.Problems.References.Chapter 2. Symmetric Dielectric Slab Waveguides.2.1. Ray Analysis of the Slab Waveguides.2.2. Field Analysis of the Slab Waveguides.2.3. Solutions of the Eigenvalue Equations.2.4. Power Transmission and Confinement.2.5. Leaky Waves.2.6. Radiation Modes.2.7. Wave Propagation in Curved Slab Waveguides.Problems.References.Chapter 3. Weakly-Guiding Fibers with Step Index Profiles.3.1. Rays and Fields in the Step Index Fiber.3.2. Field Analysis of the Weakly-Guiding Fiber.3.3. Eigenvalue Equation for LP Modes.3.4. LP Mode Characteristics.3.5. Single Mode Fiber Parameters.3.6. Derivation of the General Step Index Fiber Modes.Problems.References.Chapter 4. Loss Mechanisms in Silica Fiber.4.1. Basic Loss Effects in Transmission.4.2. Fabrication of Silica Fibers.4.3. Intrinsic Loss.4.4. Extrinsic Loss.4.5. Bending Loss.4.6. Source-to-Fiber Coupling.Problems.References.Chapter 5. Dispersion.5.1. Pulse Propagation in Media Possessing Quadratic Dispersion.5.2. Material Dispersion.5.3. Dispersion in Optical Fiber.5.4. Chromatic Dispersion Compensation.5.5. Polarization Dispersion.5.6. System Considerations and Dispersion Measurement.Problems.References.Chapter 6. Special Purpose Index Profiles.6.1. Multimode Graded Index Fiber.6.2. Special Index Profile Optimization.Problems.References.Chapter 7. Nonlinear Effects in Fibers I: Non-Resonant Processes.7.1. Nonlinear Optics Fundamentals.7.2. Nonlinear Phase Modulation on Pulses.7.3. The Nonlinear Schrodinger Equation.7.4. Additional Non-Resonant Processes.Problems.References.Chapter 8. Nonlinear Effects in Fibers II: Resonant Processes and Amplification.8.1. Raman Scattering.8.2. Stimulated Brillouin Scattering.8.3. Rare-Earth-Doped Fiber Amplifiers.Problems.References.Appendix A: Properties of Bessel Functions.Appendix B: Notation.Index.

328 citations

Journal ArticleDOI
15 Sep 2018-Sensors
TL;DR: Some advanced applications and key sectors of the global fibre-optic strain sensors market are envisaged, as well as the main market players acting in this field.
Abstract: Fibre Bragg grating (FBG) strain sensors are not only a very well-established research field, but they are also acquiring a bigger market share due to their sensitivity and low costs In this paper we review FBG strain sensors with high focus on the underlying physical principles, the interrogation, and the read-out techniques Particular emphasis is given to recent advances in highly-performing, single head FBG, a category FBG strain sensors belong to Different sensing schemes are described, including FBG strain sensors based on mode splitting Their operation principle and performance are reported and compared with the conventional architectures In conclusion, some advanced applications and key sectors the global fibre-optic strain sensors market are envisaged, as well as the main market players acting in this field

280 citations

Journal ArticleDOI
TL;DR: In this article, the optical fiber sensors employed in environmental monitoring are summarized for understanding of their sensing principles and fabrication processes, followed by discussion on the potentials of OFS in manufacturing.
Abstract: Environmental monitoring has become essential in order to deal with environmental resources efficiently and safely in the realm of green technology. Environmental monitoring sensors are required for detection of environmental changes in industrial facilities under harsh conditions, (e.g. underground or subsea pipelines) in both the temporal and spatial domains. The utilization of optical fiber sensors is a promising scheme for environmental monitoring of this kind, owing to advantages including resistance to electromagnetic interference, durability under extreme temperatures and pressures, high transmission rate, light weight, small size, and flexibility. In this paper, the optical fiber sensors employed in environmental monitoring are summarized for understanding of their sensing principles and fabrication processes. Numerous specific applications in petroleum engineering, civil engineering, and agricultural engineering are explored, followed by discussion on the potentials of OFS in manufacturing.

236 citations