Roadmap on measurement technologies for next generation structural health monitoring systems

Structural health monitoring (SHM) is the automation of the condition assessment process of an engineered system. When applied to geometrically large components or structures, such as those found in civil and aerospace infrastructure and systems, a critical challenge is in designing the sensing solution that could yield actionable information. This is a difficult task to conduct cost-effectively, because of the large surfaces under consideration and the localized nature of typical defects and damages. There have been significant research efforts in empowering conventional measurement technologies for applications to SHM in order to improve performance of the condition assessment process. Yet, the field implementation of these SHM solutions is still in its infancy, attributable to various economic and technical challenges. The objective of this Roadmap publication is to discuss modern measurement technologies that were developed for SHM purposes, along with their associated challenges and opportunities, and to provide a path to research and development efforts that could yield impactful field applications. The Roadmap is organized into four sections: distributed embedded sensing systems, distributed surface sensing systems, multifunctional materials, and remote sensing. Recognizing that many measurement technologies may overlap between sections, we define distributed sensing solutions as those that involve or imply the utilization of numbers of sensors geometrically organized within (embedded) or over (surface) the monitored component or system. Multi-functional materials are sensing solutions that combine multiple capabilities, for example those also serving structural functions. Remote sensing are solutions that are contactless, for example cell phones, drones, and satellites. It also includes the notion of remotely controlled robots

Characterization and Modelling of Composites

Composites have increasingly been used in various structural components in the aerospace, marine, automotive, and wind energy sectors. The material characterization of composites is a vital part of the product development and production process. Physical, mechanical, and chemical characterization helps developers to further their understanding of products and materials, thus ensuring quality control. Achieving an in-depth understanding and consequent improvement of the general performance of these materials, however, still requires complex material modeling and simulation tools, which are often multiscale and encompass multiphysics. This Special Issue aims to solicit papers concerning promising, recent developments in composite modeling, simulation, and characterization, in both design and manufacturing areas, including experimental as well as industrial-scale case studies. All submitted manuscripts will undergo a rigorous review process and will only be considered for publication if they meet journal standards. Selected top articles may have their processing charges waived at the recommendation of reviewers and the Guest Editor

Contribution to the development of new photonic systems for fiber optic sensing applications

En este trabajo de doctorado se presentan nuevos sistemas y subsistemas de sensores de fibra óptica. Así, se proponen y desarrollan nuevas técnicas, componentes y tecnologías basadas en láseres de fibra con espejos distribuidos (random), fibras de cristal fotónico, estructuras de luz lenta, multiplexores de inserción y extracción (add and drop), conmutadores tele-alimentados por luz, reflectometría óptica tanto en el dominio del tiempo como de la frecuencia o filtros ópticos reconfigurables. También se han demostrado nuevas aplicaciones para estructuras de sensores tradicionales y técnicas de medida ya conocidas. Todas ellas dirigidas a la mejora del funcionamiento de los actuales transductores, redes de sensores y aplicaciones de monitorización de salud estructural. De este modo, y en primer lugar, se han desarrollado nuevos transductores puntuales. En concreto, dos sensores interferométricos basados en fibras de cristal fotónico y otro basado en una estructura resonante en anillo. También se han realizado diferentes redes de sensores utilizando OTDRs comerciales. Por un lado, se han multiplexado diferentes sensores utilizando una red en forma de bus y, por el otro, se ha interrogado de manera remota un sensor FLM/LPG a una distancia de 253 km sin necesidad de amplificación. Se han estudiado láseres basados en efecto de realimentación distribuida random (RDFB) para su uso en interrogación de sensores. Para ello, se han demostrado dos nuevos láseres multi-longitud de onda y también, por primera vez, se ha modulado un laser random. Después, se han demostrado experimentalmente varias redes de sensores de fibra óptica teniendo en cuenta los principales desafíos que estas presentan: multiplexar varios sensores en una misma red y permitir su monitorización de manera remota. En primer lugar, se han multiplexado sensores basados en la modulación de la intensidad óptica utilizando técnicas de multiplexación en dominio del tiempo. En segundo lugar, se han multiplexado sensores basados en fibras de cristal fotónico. En tercer lugar, se presentan tres nuevos métodos para la medida remota de sensores. Por último, se incluye la demostración de un conmutador de fibra óptica tele-alimentado a través de luz. Éste se utiliza en tres redes diferentes para añadir robustez e incrementar la versatilidad en la multiplexación. Finalmente, se han realizado tres pruebas de campo para aplicaciones de monitorización de salud estructural.In this PhD work, different new photonic systems and subsystems for fiber optic sensing are presented. The aim of this thesis has been to contribute to the fiber optic sensors field using modern techniques, components and technologies such as random fiber lasers, photonic crystal fibers, slow light structures, add and drop multiplexers, powered by light switches, optical frequency and time domain reflectometry or reconfigurable optical filters, among others. New applications of traditional sensing structures or techniques have been also demonstrated. All of them focused on improving the performance of current sensors transducers, multiplexing networks and structural health monitoring applications. Thus, new point transducers have been developed: two of them are interferometric sensors based on photonic crystal fibers; and another one is based on a fiber ring resonator structure. Fiber optic sensor networks using commercial OTDRs have been also explored. On the one hand, different sensors have been successfully multiplexed in the same bus network. And, on the other hand, a FLM/LPG sensor was remotely interrogated at a distance of 253 km without using amplification. Random distributed feedback (RDFB) lasers have been explored for sensors interrogation. Two multi-wavelength Raman fiber lasers suitable for sensors interrogation have been demonstrated. Also, a random fiber laser has been internally modulated for the first time. Then, some experimental demonstrations of fiber optic sensors networks have been carried out taking into account the principal challenges they pose: multiplexing a number of optical sensors in a single networks, and enabling the possibility of remote sensing. Firstly, intensity sensors using TDM technology have been multiplexed. Secondly, PCF sensors have been successfully multiplexed. Thirdly, three new approaches to enable remote sensing are presented. Finally, a remote powered by light fiber optic switch have been included in three networks in order to add robustness and multiplexing versatility.Este trabajo se ha llevado a cabo gracias a las aportaciones económicas recibidas de los siguientes organismos, entre otros: - Secretaría de Estado de Investigación, Desarrollo e Innovación, Ministerio de Economía y Competitividad de España a través del programa de Formación del Personal Investigador y asociado al proyecto de investigación TEC2010-20224-C02-01. - Universidad Pública de Navarra mediante las ayudas a tesis doctorares. - Acción Europea COST- TD1001: Novel and Reliable Optical Fibre Sensor Systems for Future Security and Safety Applications (OFSeSa) - También se ha recibido financiación del Proyecto de Investigación de la Secretaría de Estado de Investigación, Desarrollo e Innovación, Ministerio de Economía y Competitividad de España TEC2013-47264-C2-2-R, de Innocampus, del Proyecto Europeo SUDOE-ECOAL-Intereg Project ECOAL-MGT y de los Fondos FEDER.Programa Oficial de Doctorado en Tecnologías de las Comunicaciones (RD 1393/2007)Komunikazioen Teknologietako Doktoretza Programa Ofiziala (ED 1393/2007

Biomedical Engineering

Biomedical engineering is currently relatively wide scientific area which has been constantly bringing innovations with an objective to support and improve all areas of medicine such as therapy, diagnostics and rehabilitation. It holds a strong position also in natural and biological sciences. In the terms of application, biomedical engineering is present at almost all technical universities where some of them are targeted for the research and development in this area. The presented book brings chosen outputs and results of research and development tasks, often supported by important world or European framework programs or grant agencies. The knowledge and findings from the area of biomaterials, bioelectronics, bioinformatics, biomedical devices and tools or computer support in the processes of diagnostics and therapy are defined in a way that they bring both basic information to a reader and also specific outputs with a possible further use in research and development

Advanced Interrogation of Fiber-Optic Bragg Grating and Fabry-Perot Sensors with KLT Analysis

The Karhunen-Loeve Transform (KLT) is applied to accurate detection of optical fiber sensors in the spectral domain. By processing an optical spectrum, although coarsely sampled, through the KLT, and subsequently processing the obtained eigenvalues, it is possible to decode a plurality of optical sensor results. The KLT returns higher accuracy than other demodulation techniques, despite coarse sampling, and exhibits higher resilience to noise. Three case studies of KLT-based processing are presented, representing most of the current challenges in optical fiber sensing: (1) demodulation of individual sensors, such as Fiber Bragg Gratings (FBGs) and Fabry-Perot Interferometers (FPIs); (2) demodulation of dual (FBG/FPI) sensors; (3) application of reverse KLT to isolate different sensors operating on the same spectrum. A simulative outline is provided to demonstrate the KLT operation and estimate performance; a brief experimental section is also provided to validate accurate FBG and FPI decoding

Micro-/Nano-Fiber Sensors and Optical Integration Devices

The development of micro/nanofiber sensors and associated integrated systems is a major project spanning photonics, engineering, and materials science, and has become a key academic research trend. During the development of miniature optical sensors, different materials and micro/nanostructures have been reasonably designed and functionalized on the ordinary single-mode optical fibers. The combination of various special optical fibers and new micro/nanomaterials has greatly improved the performance of the sensors. In terms of optical integration, micro/nanofibers play roles in independent and movable optical waveguide devices, and can be conveniently integrated into two-dimensional chips to realize the efficient transmission and information exchange of optical signals based on optical evanescent field coupling technology. In terms of systematic integration, the unique optical transmission mode of optical fiber has shown great potential in the array and networking of multiple sensor units.In this book, more than ten research papers were collected and studied, presenting research on optical micro/nanofiber devices and related integrated systems, covering high-performance optical micro/nanofiber sensors, fine characterization technologies for optical micro/nanostructures, weak signal detection technologies in photonic structures, as well as fiber-assisted highly integrated optical detection systems

Life cycle monitoring of composite aircraft components with structural health monitoring technologies

Life cycle monitoring could considerably improve the economy and sustainability of composite aircraft components. Knowledge about the quality of a component and its structural health allows thorough exploitation of it’s useful life and offers opportunity for optimization. Current life cycle monitoring efforts can be split in two main fields 1) process monitoring and 2) structural health monitoring with little overlap between them. This work aims to propose an integral monitoring approach, enabling entire life monitoring with the same sensor. First, the state of the art of both composite manufacturing as well as structural health monitoring technologies is presented. Piezoelectric sensors have been ruled out for further investigation due their brittleness. Fiber optical sensors and electrical property-based methods are further investigated. Distributed fiber optic sensors have been successfully used in composite manufacturing trials. Two processes were demonstrated: vacuum assisted resin transfer molding and resin infusion under flexible tooling. Due to their flexibility, optical fibers can survive the loads occurring during manufacturing and deliver valuable insights. It is shown for the first time numerically and experimentally, that fiber bed compaction levels and volume fractions can be calculated from the optical frequency shift measured by the optical fiber sensors. The same sensor was used for subsequent structural health monitoring. This proves that the gap between process monitoring and structural health monitoring can be closed with mutual benefits in both areas. The final chapter presents a novel electrical property-based sensing technique. The sensors are highly flexible and manufactured with a robot-based 3D-printing method. They are shown to reliably work as strain sensors and crack detectors. This work presents a thorough investigation of available and novel sensing technologies for process monitoring and structural health monitoring settings. The results obtained could pave the way to more efficient aircraft structures.Open Acces

The Public Service Media and Public Service Internet Manifesto

This book presents the collectively authored Public Service Media and Public Service Internet Manifesto and accompanying materials.The Internet and the media landscape are broken. The dominant commercial Internet platforms endanger democracy. They have created a communications landscape overwhelmed by surveillance, advertising, fake news, hate speech, conspiracy theories, and algorithmic politics. Commercial Internet platforms have harmed citizens, users, everyday life, and society. Democracy and digital democracy require Public Service Media. A democracy-enhancing Internet requires Public Service Media becoming Public Service Internet platforms – an Internet of the public, by the public, and for the public; an Internet that advances instead of threatens democracy and the public sphere. The Public Service Internet is based on Internet platforms operated by a variety of Public Service Media, taking the public service remit into the digital age. The Public Service Internet provides opportunities for public debate, participation, and the advancement of social cohesion. Accompanying the Manifesto are materials that informed its creation: Christian Fuchs’ report of the results of the Public Service Media/Internet Survey, the written version of Graham Murdock’s online talk on public service media today, and a summary of an ecomitee.com discussion of the Manifesto’s foundations

Roadmap on measurement technologies for next generation structural health monitoring systems

Structural health monitoring (SHM) is the automation of the condition assessment process of an engineered system. When applied to geometrically large components or structures, such as those found in civil and aerospace infrastructure and systems, a critical challenge is in designing the sensing solution that could yield actionable information. This is a difficult task to conduct cost-effectively, because of the large surfaces under consideration and the localized nature of typical defects and damages. There have been significant research efforts in empowering conventional measurement technologies for applications to SHM in order to improve performance of the condition assessment process. Yet, the field implementation of these SHM solutions is still in its infancy, attributable to various economic and technical challenges. The objective of this Roadmap publication is to discuss modern measurement technologies that were developed for SHM purposes, along with their associated challenges and opportunities, and to provide a path to research and development efforts that could yield impactful field applications. The Roadmap is organized into four sections: distributed embedded sensing systems, distributed surface sensing systems, multifunctional materials, and remote sensing. Recognizing that many measurement technologies may overlap between sections, we define distributed sensing solutions as those that involve or imply the utilization of numbers of sensors geometrically organized within (embedded) or over (surface) the monitored component or system. Multi-functional materials are sensing solutions that combine multiple capabilities, for example those also serving structural functions. Remote sensing are solutions that are contactless, for example cell phones, drones, and satellites. It also includes the notion of remotely controlled robots

Novel Specialty Optical Fibers and Applications

Novel Specialty Optical Fibers and Applications focuses on the latest developments in specialty fiber technology and its applications. The aim of this reprint is to provide an overview of specialty optical fibers in terms of their technological developments and applications. Contributions include:1. Specialty fibers composed of special materials for new functionalities and applications in new spectral windows.2. Hollow-core fiber-based applications.3. Functionalized fibers.4. Structurally engineered fibers.5. Specialty fibers for distributed fiber sensors.6. Specialty fibers for communications