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Although pregnancy poses a greater risk for severe COVID-19, the underlying immunological changes associated with SARS-CoV-2 infection during pregnancy are poorly understood. We defined immune responses to SARS-CoV-2 in pregnant and non-pregnant women during acute and convalescent COVID-19 up to 258 days post symptom onset, quantifying 217 immunological parameters. Additionally, matched maternal and cord blood were collected from COVID-19 convalescent pregnancies. Although serological responses to SARS-CoV-2 were similar in pregnant and non-pregnant women, cellular immune analyses revealed marked differences in key NK cell and unconventional T cell responses during COVID-19 in pregnant women. While NK, γδ T cells and MAIT cells displayed pre-activated phenotypes in healthy pregnant women when compared to non-pregnant age-matched women, activation profiles of these pre-activated NK and unconventional T cells remained unchanged at acute and convalescent COVID-19 in pregnancy. Conversely, activation dynamics of NK and unconventional T cells were prototypical in non-pregnant women in COVID-19. In contrast, activation of αβ CD4+ and CD8+ T cells, T follicular helper cells and antibody-secreting cells was similar in pregnant and non-pregnant women with COVID-19. Elevated levels of IL-1β, IFN-γ, IL-8, IL-18 and IL-33 were also found in pregnant women in their healthy state, and these cytokine levels remained elevated during acute and convalescent COVID-19. Collectively, our study provides the first comprehensive map of longitudinal immunological responses to SARS-CoV-2 infection in pregnant women, providing insights into patient management and education during COVID-19 pregnancy.

Although the respiratory tract is the primary site of SARS-CoV-2 infection and the ensuing immunopathology, respiratory immune responses are understudied and urgently needed to understand mechanisms underlying COVID-19 disease pathogenesis. We collected paired longitudinal blood and respiratory tract samples (endotracheal aspirate, sputum or pleural fluid) from hospitalized COVID-19 patients and non-COVID-19 controls. Cellular, humoral and cytokine responses were analysed and correlated with clinical data. SARS-CoV-2-specific IgM, IgG and IgA antibodies were detected using ELISA and multiplex assay in both the respiratory tract and blood of COVID-19 patients, although a higher receptor binding domain (RBD)-specific IgM and IgG seroconversion level was found in respiratory specimens. SARS-CoV-2 neutralization activity in respiratory samples was detected only when high levels of RBD-specific antibodies were present. Strikingly, cytokine/chemokine levels and profiles greatly differed between respiratory samples and plasma, indicating that inflammation needs to be assessed in respiratory specimens for the accurate assessment of SARS-CoV-2 immunopathology. Diverse immune cell subsets were detected in respiratory samples, albeit dominated by neutrophils. Importantly, we also showed that dexamethasone and/or remdesivir treatment did not affect humoral responses in blood of COVID-19 patients. Overall, our study unveils stark differences in innate and adaptive immune responses between respiratory samples and blood and provides important insights into effect of drug therapy on immune responses in COVID-19 patients.

T-cell responses to SARS-CoV-2-derived peptide pools have been documented, however it remains largely unclear whether prominent SARS-CoV-2-specific T cell populations originate from naive or pre-existing memory sets. As HLA-B*07:02-restricted N105-113 epitope (B7/N105) is the most dominant SARS-CoV-2 CD8+ T-cell specificity to date, we dissected CD8+ T-cell responses directed at this epitope by direct ex vivo analyses in peripheral blood mononuclear cells (PBMCs) from acute and convalescent COVID-19 patients, and pre-pandemic PBMCs, tonsils, lungs and spleens. Using peptide-HLA tetramers, immunodominant B7/N105+CD8+ T-cells were detected at a high frequency (∼2.18x10-4) in COVID-19 patients, comparable to the well-established influenza-specific A2/M158+CD8+ T-cell population. Remarkably, frequencies of B7/N105+CD8+ T-cells were also readily detectable in pre-pandemic PBMCs and tonsils (at 6.55x10-5 and 2.76x10-4, respectively), although they mainly displayed a naive phenotype, indicating a lack of previous cross-reactive exposures. Ex vivo TCRαβ analyses revealed that a diverse TCRαβ repertoire and promiscuity in αβ TCR pairing underlie such high naive precursor frequencies of B7/N105+CD8+ T-cells. Overall, our study demonstrates that high precursor frequency and plasticity of TCRα-TCRβ pairing underpin immunodominance of SARS-CoV-2-specific B7/N105+CD8+ T-cell responses and advocates for vaccine strategies which include the nucleocapsid protein to elicit immunodominant CD8+ T-cell responses in HLA-B*07:02 individuals. Funding: This work was supported by theClifford Craig Foundation to KLF and KK, NHMRC Leadership Investigator Grant to KK (1173871), NHMRC Program Grant to DLD (#1132975), Research Grants Council of theHong Kong Special Administrative Region, China (#T11-712/19-N) to KK, the Victorian Government (SJK, AKW), MRFF award (#2002073) to SJK and AKW, MRFFAward (#1202445) to KK, NHMRC program grant 1149990 (SJK) and NHMRC project grant 1162760 (AKW). AKW is supported by Emerging Leadership 1 Investigator Grant (#1173433), JAJ by an NHMRC Early Career Fellowship (ECF) (#1123673), KK by NHMRC SeniorResearch Fellowship (1102792), DLD by a NHMRC Principal Research Fellowship(#1137285) and SJK by NHMRC Senior Principal Research Fellowship (#1136322). CES has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement (#792532). JR is supported by an ARC Laureate fellowship. JRH and WZ are supported by the Melbourne Research Scholarship from The University of Melbourne. LH is supported by the Melbourne International Research Scholarship (MIRS) and the Melbourne International Fee Remission Scholarship (MIFRS) from The University of Melbourne. Ethical Approval: Experiments conformed to the Declaration of Helsinki Principles and theAustralian National Health and Medical Research Council Code of Practice. Written informed consents were obtained from all blood donors prior to the study. Lung and spleen tissues were obtained from deceased organ donors after written informed consents from the next of kin.Written informed consents were obtained from participants’ parental or guardians for underage tonsil tissue donors. The study was approved by the Alfred Hospital (#280/14), Austin Health (HREC/63201/Austin-2020); the University of Melbourne (#2057366.1, #2056901.1,#2056689, #2056761, #1442952, #1955465, and #1443389), the Australian Red CrossLifeblood (ID 2015#8), the Tasmanian Health and Medical (ID H0017479) and the James Cook University (H7886) Human Research Ethics Committees.

SARS-CoV-2 causes a spectrum of illness, ranging from asymptomatic to severe COVID-19. As the immunological basis for severity remains ill-defined, we analysed 78 SARS-CoV-2-infected individuals at acute and/or convalescent timepoints, up to 102 days post-symptom onset, quantifying 184 innate and adaptive immunological parameters. Acute COVID-19 in hospitalised patients was associated with high levels of IL-6, IL-18 and IL-10, elevated neutrophil-to-lymphocyte and neutrophil-to-T cell ratios, and high proportions of activated CD38+ neutrophils, CD38+ eosinophils, CD38+ HLA-DRlo monocytes, CD38+CD56dim NK cells, CD38+ γδ T cells, antibody-secreting cells, CD38+ICOS+ circulating T follicular helper (cTFH) cells, CD38+HLA-DR+CD4+ T cells, effector CD27-CD45RA+ and CD38+ CD8+ T cells. During convalescence, elevated seroconversion and neutralising antibodies were prominent and correlated with acute CXCR3+ cTFH cell activation. Strikingly, intensive care unit (ICU) patients with severe COVID-19 displayed higher levels of soluble IL-6R, IL-18, and hyperactivation of innate, adaptive and myeloid compartments than ward patients with moderate disease. Our analyses provide a comprehensive map of longitudinal immunological responses in COVID-19 patients during acute and convalescent phases of SARS-CoV-2 infection, and integrate key cellular pathways of complex perturbed immune networks that underpin severe COVID-19, providing important insights into potential biomarkers and immunotherapies. Funding: This work was supported by the Australian National Health and Medical Research Council (NHMRC) Leadership Investigator Grant to KK (#1173871), NHMRC Program Grant to DLD (#1132975), Research Grants Council of the Hong Kong Special Administrative Region, China (#T11-712/19-N) to KK, the Jack Ma Foundation to KK, KS, DIG and AWC, the a2 milk foundation to KS, the Victorian Government MRFF award (#2002073) to SJK, DIG and AKW, MRFF Award (#1202445) to KK, NHMRC program grant 1149990 (SJK), NHMRC project grant 1162760 (AKW), NHMRC Program Grant (#1071916) to KK and DCJ, NHMRC Program Grant (1113293) to DIG, the Merridew Foundation to NJCK. KK is supported by NHMRC Senior Research Fellowship (1102792), DLD by a NHMRC Principal Research Fellowship (#1137285), KS by an NHMRC Investigator grant (#1177174), SYCT by a NHMRC Career Development Fellowship (#1145033), DIG by an NHMRC Senior Principal Research Fellowship (#1117766) and SJK by NHMRC Senior Principal Research Fellowship (#1136322). SRL is supported by an NHMRC program grant (#1149990) and practitioner fellowship (#1135851). LH and WZ are supported by the Melbourne International Research Scholarship (MIRS) and the Melbourne International Fee Remission Scholarship (MIFRS) from The University of Melbourne. XJ is supported by China Scholarship Council-University of Melbourne joint Scholarship. CES has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement (#792532). JRH and WZ are supported by the Melbourne Research Scholarship from The University of Melbourne. TMA and FM-W are International Society for Advancement of Cytometry Marylou Ingram Scholars. GHP is supported by the Australian Government Research Training Program (RTP) Scholarship. JAJ is supported by an NHMRC Early Career Fellowship (ECF) (#1123673). EBC. is supported by a NHMRC Peter Doherty Fellowship (#1091516). KK and AC were supported by the University of Melbourne Dame Kate Campbell Fellowship. The Melbourne WHO Collaborating Centre for Reference and Research on Influenza is supported by the Australian Government Department of Health. Conflict of Interest: The authors declare no conflict of interest. Ethical Approval: The study was approved by the Alfred Hospital (#280/14), Melbourne Health (HREC/17/MH/53), Monash Health (HREC/15/MonH/64/2016.196), The University of Melbourne (#2056689, #2056761, #1442952, #1955465 and #1443389) and James Cook University (H7886) Human Research Ethics Committees.

This work presents a further development of the methods of simultaneous determination of temperature and axial strain using a single fibre Bragg grating (FBG). The reflected spectrum of composite-embedded FBG sensors has been analyzed in order to separate temperature and load effects. We found out that during the curing process of the laminates, a superstructure has been introduced on the FBG. Analyzing this effect, a temperature and strain separation was implemented by simply calculating and comparing the integrated intensity of the spectral response signal. A mathematical four-parametric model has been developed to calculate the reflected spectrum of a superstructured fibre Bragg grating. The mathematically achieved data has been evaluated with experimentally determined data from fibre Bragg gratings embedded in glass-fibre reinforced composite materials.

A fiber Bragg grating (FBG) strain patch specially adapted for long-term and high-strain applications has been developed and characterized. The design concept for the patch is based on a glass-fiber reinforced plastic (gfrp) carrier material. The developed concept for the FBG integration into the carrier material was derived from reliable integration procedure of FBG sensors into composite structures. The patches’ temperature sensitivity, strain gauge factor, fiber–matrix interface adhesion and fatigue behavior were characterized. As a result, FBG strain patches with linear temperature and strain behavior, as well as excellent fatigue resistance, were developed and can be used as part of a monitoring system for advanced composite materials in aerospace structures or wind turbine power plants.

Measurement and data recording systems are important parts of a holistic Structural Health Monitoring (SHM) system. New sensor technologies such as fiber-optic sensors are often used; however, standards (or at least guidelines) are not yet available or internationally approved. This lack in standardization makes the acceptance of FOS technologies in complex SHM systems substantially difficult. A standard family for different FOS technologies is therefore being developed that should help to design SHM systems in an optimal way. International standardization activities take place in several standardization bodies such as IEC and ASTM, and within SHM societies such as ISHMII. The paper reports on activities in standardization of fiber-optic sensors, on results already achieved, and on newly started projects. Combined activities of fiber sensor experts and SHM experts from Civil Engineering are presented. These contributions should help owners of structures as well as developers of sensors and monitoring systems to select effective and validated sensing technologies. Using these standards, both parties find recommendations how to proceed in development of SHM systems to evaluate the structural behavior based on e.g. standardized fiber optic sensors, and to derive necessary measures, e.g. the optimal maintenance strategy.

In Germany, the first guideline for the use of fiber Bragg grating strain sensors, “Optical Strain Sensor based on Fiber Bragg Grating” (Berlin, Germany: Beuth-Verlag, 2010), has been developed by the GESA guideline group of VDI, “The Association of German Engineers” and published by Beuth-Verlag. This guideline provides the basic specifications of this sensor type and the sensor characteristics, which have to be known for a reliable sensor performance. In conformity to this guideline, experimental investigations on the strain transfer characteristics of fiber Bragg grating patches have been carried out. A comparison between patches and resistance strain gauges during tensile tests and combined temperature and tensile loading was carried out. The evaluated strain gauge factor and the temperature sensitivity of the strain gauge factor have been compared to the manufacturer's data. The overall performance of the patches has been evaluated. The experimental investigations showed that there are considerable disagreements between the manufacturer's specifications and the observed characteristics.

The NEMO collaboration proposes to build an underwater neutrino telescope located South-East off the Sicily coast. This paper describes the concepts underlying the communication link design going over the whole data acquisition and transport from the front-end electronics to the module sending data on-shore through a fiber optic link which relies on Dense Wavelength Division Multiplexing. An on-shore board, plugged into a PC, extracts and distributes data both to first-level trigger and control systems. Underwater apparatus monitoring and controls are guaranteed by oceanographic instruments and dedicated sensors, whose data are packed and sent back to shore using the same optical link. The communication is fully bidirectional, allowing transmission of timing and control commands. The architecture described here provides a complete real-time data transport layer between the onshore laboratory and the underwater detector. During winter 2006 a first prototype of the apparatus has been deployed: calibration results from the currently working system are here reported.

Different types of fiber-optic sensors based on glass or polymeric fibers are used to evaluate material behavior or to monitor the integrity and long-term stability of load-bearing structure components. Fiber-optic sensors have been established as a new and innovative measurement technology in very different fields, such as material science, civil engineering, light-weight structures, geotechnical areas as well as chemical and high-voltage substations. Very often, mechanical quantities such as deformation, strain or vibration are requested. However, measurement of chemical quantities in materials and structure components, such as pH value in steel reinforced concrete members also provides information about the integrity of concrete structures. A special fiber-optic chemical sensor for monitoring the alkaline state (pH value) of the cementitious matrix in steel-reinforced concrete structures with the purpose of early detection of corrosion-initiating factors is described. The paper presents the use of several fiber-optic sensor technologies in engineering. One example concerns the use of highly resolving concrete-embeddable fiber Fabry-Perot acoustic emission (AE) sensors for the assessment of the bearing behaviour of large concrete piles in existing foundations or during and after its installation. Another example concerns fiber Bragg grating (FBG) sensors attached to anchor steels (micro piles) to measure the strain distribution in loaded soil anchors. Polymer optical fibers (POF) can be — because of their high elasticity and high ultimate strain — well integrated into textiles to monitor their deformation behaviour. Such “intelligent” textiles are capable of monitoring displacement of soil or slopes, critical mechanical deformation in geotechnical structures (dikes, dams, and embankments) as well as in masonry structures during and after earthquakes.

Zusammenfassung Die Dauerhaftigkeit von Betonbauteilen zu einer messbaren Größe zu machen, ist ein vorrangiges Ziel der Baustoffforschung. Schrumpfen, Schwinden und Temperaturverformungen gefährden bei Hochleistungsbetonen deren Dauerhaftigkeit. Die begleitende messtechnische Deformationsmessung wird daher zu einer unverzichtbaren Methode, Betonrezepturen zielsicher und ökonomisch hinsichtlich der Dauerhaftigkeit zu entwickeln. Ein flexibler Fabry–Pérot-Interferometer-Sensor ermöglicht die messtechnische Erfassung der frühen Deformationsprozesse bereits ab dem Moment des Betoneinbaus. Der Artikel zeigt das Sensorprinzip, Untersuchungen zur In-situ-Referenzierung und zur Rückwirkung des Sensors sowie dessen Einsatzmöglichkeiten in der Baustoff- und Materialforschung.

Zusammenfassung Zur Gründung von Bauwerken auf weichen, gering tragfähigen Böden werden unter anderem Betonpfähle, einzeln oder in Pfahlgruppen, eingesetzt. Deren Bewertung bzgl. Tragverhalten bzw. Integrität ist bei bestimmten Baugrundverhältnissen und Pfahlgeometrien schwierig. Hierfür werden statische und dynamische Pfahlprüfungen durchgeführt. Aus Messwerten vom Pfahlkopf bzw. vom oberen Pfahlbereich werden üblicherweise die notwendigen Aussagen abgeleitet. Eine genauere Bewertung ist möglich, wenn präzise Messwerte über die gesamte Pfahllänge vorliegen. Deshalb wurden hochauflösende betoneinbettbare Messwertaufnehmer auf Basis von Faser-Fabry-Perot-Sensoren entwickelt, die in Modell- und in realen Rammpfählen getestet wurden. Der Beitrag beschreibt den Sensor, die Installation und exemplarisch einige Testergebnisse zur Erfassung der Wellenausbreitung im Modellpfahl. Feldtests wurden zurzeit der Erstellung des Manuskripts erfolgreich begonnen.

[EN] The KM3NeT research infrastructure, currently under construction in the Mediterranean Sea, will host neutrino telescopes for the identification of neutrino sources in the Universe and for studies of the neutrino mass hierarchy. These telescopes will house hundreds of thousands of photomultiplier tubes that will have to be operated in a stable and reliable fashion. In this context, the stability of the dark counts has been investigated for photomultiplier tubes with negative high voltage on the photocathode and held in insulating support structures made of 3D printed nylon material. Small gaps between the rigid support structure and the photomultiplier tubes in the presence of electric fields can lead to discharges that produce dark count rates that are highly variable. A solution was found by applying the same insulating varnish as used for the high voltage bases directly to the outside of the photomultiplier tubes. This transparent conformal coating provides a convenient and inexpensive method of insulation., The authors acknowledge the financial support of the funding agencies: Centre National de la Recherche Scientifique (CNRS), Commission Europeenne (FEDER fund and Marie Curie Program), Institut Universitaire de France (IUF), IdEx program and UnivEarthS Labex program at Sorbonne Paris Cite (ANR-10-LABX-0023 and ANR-11-IDEX-0005-02), France; The General Secretariat of Research and Technology (GSRT), Greece; Istituto Nazionale di Fisica Nucleare (INFN), Ministero dell'Istruzione, dell'Universita e della Ricerca (MIUR), Italy; Agence de l'Oriental and CNRST, Morocco; Stichting voor Fundamenteel Onderzoek der Materie (FOM), Nederlandse organisatie voorWetenschappelijk Onderzoek (NWO), the Netherlands; National Authority for Scientific Research (ANCS), Romania; Plan Estatal de Investigacion (refs. FPA2015-65150-C3-1-P, -2-P and -3-P, (MINECO/FEDER)), Severo Ochoa Centre of Excellence and MultiDark Consolider (MINECO), and Prometeo and Grisolia programs (Generalitat Valenciana), Spain.

A prototype detection unit of the KM3NeT deep-sea neutrino telescope has been installed at 3500m depth 80 km offshore the Italian coast. KM3NeT in its final configuration will contain several hundreds of detection units. Each detection unit is a mechanical structure anchored to the sea floor, held vertical by a submerged buoy and supporting optical modules for the detection of Cherenkov light emitted by charged secondary particles emerging from neutrino interactions. This prototype string implements three optical modules with 31 photomultiplier tubes each. These optical modules were developed by the KM3NeT Collaboration to enhance the detection capability of neutrino interactions. The prototype detection unit was operated since its deployment in May 2014 until its decommissioning in July 2015. Reconstruction of the particle trajectories from the data requires a nanosecond accuracy in the time calibration. A procedure for relative time calibration of the photomultiplier tubes contained in each optical module is described. This procedure is based on the measured coincidences produced in the sea by the $$^{40}$$40K background light and can easily be expanded to a detector with several thousands of optical modules. The time offsets between the different optical modules are obtained using LED nanobeacons mounted inside them. A set of data corresponding to 600 h of livetime was analysed. The results show good agreement with Monte Carlo simulations of the expected optical background and the signal from atmospheric muons. An almost background-free sample of muons was selected by filtering the time correlated signals on all the three optical modules. The zenith angle of the selected muons was reconstructed with a precision of about 3$$^circ $$∘.

Embedded conventional fibre Bragg grating (FBG) sensors with acrylate coating have been chosen for monitoring novel textile-reinforced composite materials with a complicated wavy structure as a result of reinforcing textures. Problems of monitoring this type of material occur due to the harsh fabrication technology of the composite and its complicated structure. Embedded fibre sensors are exposed to the influence of transverse and point-wise deformations. To what extent will these effects influence the measurement signal of a sensor? Temperature cycles, tension and vibration tests were carried out to answer this question. Transverse and point-wise deformation and micromechanical indentation tests on non-embedded FBG sensors were carried out to clarify the reliability of recorded signals.

The NEMO Collaboration installed and operated an underwater detector including prototypes of the critical elements of a possible underwater km3 neutrino telescope: a four-floor tower (called Mini-Tower) and a Junction Box. The detector was developed to test some of the main systems of the km3 detector, including the data transmission, the power distribution, the timing calibration and the acoustic positioning systems as well as to verify the capabilities of a single tridimensional detection structure to reconstruct muon tracks. We present results of the analysis of the data collected with the NEMO Mini-Tower. The position of photomultiplier tubes (PMTs) is determined through the acoustic position system. Signals detected with PMTs are used to reconstruct the tracks of atmospheric muons. The angular distribution of atmospheric muons was measured and results compared with Monte Carlo simulations., Astrop. Phys., accepted

none 104 The selection of the photomultiplier plays a crucial role in the R&D activity related to a large-scale underwater neutrino telescope. This paper illustrates the main procedures and facilities used to characterize the performances of 72 large area photomultipliers, Hamamatsu model R7081 sel. The voltage to achieve a gain of 5×107, dark count rate and single photoelectron time and charge properties of the overall response were measured with a properly attenuated 410 nm pulsed laser. A dedicated study of the spurious pulses was also performed. The results prove that the photomultipliers comply with the general requirements imposed by the project. ISSN 0168-9002 doi:10.1016/j.nima.2009.12.040 none S. AIELLO; A. ALOISIO; F. AMELI; I.AMORE; M. ANGHINOLFI; A. ANZALONE; G. BARBARINO; E. BARBARITO; M.BATTAGLIERI; M.BAZZOTTI; R. BELLOTTI; A. BERSANI; N. BEVERINI; S. BIAGI; M. BONORI; B. BOUHDAEF; M. BRESCIA; G. CACOPARDO; C. CALÌ; A. CAPONE; L. CAPONETTO; G. CARMINATI; B. CASSANO; E. CASTORINA; A. CERES; T. CHIARUSI; M. CIRCELLA; R. COCIMANO; R. CONIGLIONE; M. CORDELLI; M. COSTA; A. DAMICO; C. DAMATO; V. DAMATO; G. DE BONIS; G. DE ROSA; G. DE RUVO; R. DE VITA; C. DISTEFANO; E. FALCHINI; V. FLAMINIO; K. FRATINI; GABRIELLI A; S. GALEOTTI; E. GANDOLFI; G. GIACOMELLI; F. GIORGI; G. GIOVANETTI; A. GRIMALDI; A. GRMEK; R. HABEL; E. LEONORA; A. LONARDO; G. LONGO; D. LO PRESTI; F. LUCARELLI; L. MACCIONE; A. MARGIOTTA; A. MARTINI; R. MASULLO; F. MAUGERI; R. MEGNA; E. MIGNECO; S. MINUTOLI; M. MONGELLI; T. MONTARULI; M. MORGANTI; P. MUSICO; M. MUSUMECI; C.A. NICOLAU; A. ORLANDO; M. OSIPENKO; G. OSTERIA; R. PAPALEO; V. PAPPALARDO; C. PETTA; P. PIATTELLI; D. PIOMBO; G. RAIA; N. RANDAZZO; S. REITO; G. RICCO; G. RICCOBENE; M. RIPANI; A. ROVELLI; M. RUPPI; G.V. RUSSO; S. RUSSO; P. SAPIENZA; M. SEDITA; E. SHIROKOV; F. SIMEONE; V. SIPALA; C. SOLLIMA; F. SPEZIALE; M. SPURIO; M. TAIUTI; G. TERRENI; L. TRASATTI; S. URSO; V. VALENTE; M. VECCHI; P. VICINI; R. WISCHNEWSKI S. AIELLO; A. ALOISIO; F. AMELI; I.AMORE; M. ANGHINOLFI; A. ANZALONE; G. BARBARINO; E. BARBARITO; M.BATTAGLIERI; M.BAZZOTTI; R. BELLOTTI; A. BERSANI; N. BEVERINI; S. BIAGI; M. BONORI; B. BOUHDAEF; M. BRESCIA; G. CACOPARDO; C. CALÌ; A. CAPONE; L. CAPONETTO; G. CARMINATI; B. CASSANO; E. CASTORINA; A. CERES; T. CHIARUSI; M. CIRCELLA; R. COCIMANO; R. CONIGLIONE; M. CORDELLI; M. COSTA; A. DAMICO; C. DAMATO; V. DAMATO; G. DE BONIS; G. DE ROSA; G. DE RUVO; R. DE VITA; C. DISTEFANO; E. FALCHINI; V. FLAMINIO; K. FRATINI; GABRIELLI A; S. GALEOTTI; E. GANDOLFI; G. GIACOMELLI; F. GIORGI; G. GIOVANETTI; A. GRIMALDI; A. GRMEK; R. HABEL; E. LEONORA; A. LONARDO; G. LONGO; D. LO PRESTI; F. LUCARELLI; L. MACCIONE; A. MARGIOTTA; A. MARTINI; R. MASULLO; F. MAUGERI; R. MEGNA; E. MIGNECO; S. MINUTOLI; M. MONGELLI; T. MONTARULI; M. MORGANTI; P. MUSICO; M. MUSUMECI; C.A. NICOLAU; A. ORLANDO; M. OSIPENKO; G. OSTERIA; R. PAPALEO; V. PAPPALARDO; C. PETTA; P. PIATTELLI; D. PIOMBO; G. RAIA; N. RANDAZZO; S. REITO; G. RICCO; G. RICCOBENE; M. RIPANI; A. ROVELLI; M. RUPPI; G.V. RUSSO; S. RUSSO; P. SAPIENZA; M. SEDITA; E. SHIROKOV; F. SIMEONE; V. SIPALA; C. SOLLIMA; F. SPEZIALE; M. SPURIO; M. TAIUTI; G. TERRENI; L. TRASATTI; S. URSO; V. VALENTE; M. VECCHI; P. VICINI; R. WISCHNEWSKI

Optical fiber sensor (OFS) technologies have developed rapidly over the last few decades, and various types of OFS have found practical applications in the field of civil engineering. In this paper, which is resulting from the work of the RILEM technical committee “Optical fiber sensors for civil engineering applications”, different kinds of sensing techniques, including change of light intensity, interferometry, fiber Bragg grating, adsorption measurement and distributed sensing, are briefly reviewed to introduce the basic sensing principles. Then, the applications of OFS in highway structures, building structures, geotechnical structures, pipelines as well as cables monitoring are described, with focus on sensor design, installation technique and sensor performance. It is believed that the State-of-the-Art review is helpful to engineers considering the use of OFS in their projects, and can facilitate the wider application of OFS technologies in construction industry.

Performance description of fiber-optic sensor products is mostly well done; however, the performance of sensors when applied in rather harsh environment is different from those determined in laboratory before installation. Performance of applied sensors is difficult to define. Standardized procedures for evaluation of the sensor performance after application or integration into materials are necessary. The difficulty to evaluate on-site the mechanical behavior or physical and chemical processes in the sensing zone of strain sensors is described for sensors installed in offshore environment. The paper refers on current standardization activities and corresponding research activities to develop guidelines for application and integration.

We have designed and built an underwater measurement system, PORFIDO (Physical Oceanography by RFID Outreach) to gather oceanographic data from the Optical Modules of a neutrino telescope with a minimum of disturbance to the main installation. PORFIDO is composed of a sensor glued to the outside of an Optical Module, in contact with seawater, and of a reader placed inside the sphere, facing the sensor. Data are transmitted to the reader through the glass by RFID and to shore in real time for periods of years. The sensor gathers power from the radio frequency, thus eliminating the need for batteries or connectors through the glass. We have deployed four PORFIDO probes measuring temperatures with the NEMO-KM3Net-Italy Phase 2 tower in april 2013. The four probes are operative and are transmitting temperature data from 3500 m depth.

Fiber-optic strain sensors are increasingly used in very different technical fields. Sensors are provided with specifications defined by the manufacturer or ascertained by the interested user. If deformation sensors are to be used to evaluate the long-term behavior of safety-relevant structures or to monitor critical structure components, their performance and signal stability must be of high quality to enable reliable data recording. The measurement system must therefore be validated according to established technical rules and standards before its application and after. In some cases, not all details of the complex characteristic and performance of applied fiber-optic sensors are sufficiently understood, or can be validated because of a lack of knowledge and methods to check the sensors’ behavior. This contribution focusses therefore on the importance of serious validation in avoiding a decrease or even deterioration of the sensors’ function. Methods for validation of applied sensors are discussed and should reveal weaknesses in validation of embedded or integrated fiber-optic deformation and/or strain sensors. An outlook to some research work that has to be carried out to ensure a well-accepted practical use of fiber-optic sensors is given.

Fibre optic sensors for monitoring in safety-relevant structures have to be validated in order to proof their reliability under typical structural load conditions. The reliable use of optical fibre sensors depends strongly on an appropriate and qualitative application. Diagnostics of the physical condition of embedded and surface-applied fibre optic strain sensors are demonstrated on field examples. Distributed strain measurement based on Rayleigh backscattering is used to determine breakage of the fibre, interface adhesion problems and to identify application related strain transfer mechanisms.

Static and dynamic pile tests are carried out to determine the load bearing capacity and the quality of reinforced concrete piles. As part of a round robin test to evaluate dynamic load tests, structure integrated fibre optic strain sensors were used to receive more detailed information about the strains along the pile length compared to conventional measurements at the pile head. This paper shows the instrumentation of the pile with extrinsic Fabry-Perot interferometers sensors and fibre Bragg gratings sensors together with the results of the conducted static load test as well as the dynamic load tests and pile integrity tests.

Diagnosis of the operational condition of facilities in power stations and transmission networks is of significant importance to ensure their reliable operation. Early detection of incipient faults or overload avoids failure of important parts of the power supply system. Diagnostics also allows planning maintenance activities to exploit full performance of the equipment and therefore enables economical operation of the quite expensive facilities. A variety of measuring and surveillance methods as well as very different sensor types installed are used to get information about the behaviour of important facility components. This chapter gives an overview on the most important facilities to be monitored, and an introduction to diagnostic tasks and strategies applied to these facilities. The most commonly used measurement and diagnostic methods are described such as optical methods (free-space optical detection, usage of electro-optic and magneto-optic effects as well as of optical fibre-guided methods), acoustic methods and mechanical methods. These diagnostic and monitoring methods are explained based on selected examples with regard to components of high-voltage (HV) transformers, cable systems, switchgears and circuit breakers, overhead transmission lines and finally generators and motors. New developments and trends in high power facilities and grids, and the corresponding diagnostic tasks are described at the end of this chapter.

Fiber-optic sensors are increasingly used if special requirements avoid the application of electrical sensors, or economic benefit is promised. The scientific background is well developed; however, there are some restrictions with respect to long-term reliable use. For a widespread practical use, sensor products must be manufactured, characterized and validated according to standards. Guidelines on how to apply sensors and evaluate their operation on-site including special facilities to evaluate applied sensors are needed. The paper will present validation methods to evaluate the quality of sensor systems function. It will also indicate lacks of knowledge and methods to be filled to promote the use of FOS. © (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

In high-voltage facilities of power stations and transmission networks, discharge activities leading to catastrophic failure can occur. Early detection of partial discharges (PD) in polymeric insulations of HV cable terminations and joints is therefore increasingly important. This paper describes a monitoring methodology to detect PD activity in silicone elastomer by two independent fibre-optic sensor types. Fluorescent fibre-based sensors are sensitive to plasma optical emission already at the onset of PD while an acoustic fibre-optic sensor responds to acoustic emission from the PD during its progression. The sensitivities of both sensor types are compared, and it is demonstrated that they provide complementary information for fibre-optic sensor-based monitoring of high-voltage cable accessories.

In Germany, the first guideline for the use of fibre Bragg grating strain sensors, "Optical Strain Sensor based on Fibre Bragg Grating" [1], has been developed by the GESA guideline group of VDI "The Association of German Engineers" and published by Beuth Verlag. This guideline provides the basic specifications of these sensor types and the sensor characteristics which have to be known for a reliable sensor performance. In conformity to this guideline, experimental investigations on the strain transfer characteristics of fibre Bragg grating patches have been carried out. A comparison between patches and resistance strain gauges during tensile tests and combined temperature and tensile loading was carried out. The evaluated strain gauge factor and the temperature sensitivity of the strain gauge factor have been compared to the manufacturer's data. The overall performance of the patches has been evaluated. The experimental investigations showed that there are partial disagreements between the manufacturer's specifications and the observed characteristics.

The latest results and the activities towards the realization of a km 3 Cherenkov neutrino detector carried out by the NEMO Collaboration are described. The realization of a Phase-1 project has validated all relevant technologies proposed for the realization of the km 3 detector on a test site at 2000 m depth. The realization of a new infrastructure on the candidate Capo Passero site (for Phase-2 project) will provide the possibility to test detector components at 3500 m depth.

Structural health monitoring plays an important role in Europe. New structures are equipped with integrated sensor systems already during construction, existing structures are increasingly upgraded with monitoring systems to get on-line information about the state of the structure as well as the load history. A number of activities are being carried out, new projects are in the pipeline. There are several European projects which bring interdisciplinary experts together to develop new monitoring methods or to provide complex monitoring systems. This chapter gives an overview on outstanding European projects, on existing SHM networks and related events such as workshops and conferences. Main centres with SHM activities in research institutions, universities and companies in European countries are presented. A few highlighted monitoring systems developed for newly built structures (e.g. the main railway station in Berlin), for observation of safety-relevant structures (e.g. the Eder gravity dam in the German state of Hess) and to preserve architectural monuments when damage occurs (e.g. the Royal Villa in Monza in northern Italy or the San Vigilio church on Lake Lugano in Switzerland). Outlook and future trends in monitoring of European structures and a few notes on validation of monitoring systems close the chapter. Extensive research activities concerning intelligent textiles equipped with polymer optical fibre strain sensors for stabilising limited geotechnical areas as well as tiny fibre optic pH sensors to monitor the pH value of steel-reinforced concrete structures are addressed.

Sensor systems should be designed and engineered according to generally binding standards and guidelines. The use of the new fiber-optic sensor (FOS) technology requires recommendations on how to design and apply a sensor system to solve a specific measurement task. At present, corresponding national or international standards and guidelines are being developed. When customers are interested in the use of FOS technology, a multitude of reliability-related aspects have to be considered. Guidelines help give the users confidence in this new technology if they are strictly observed during manufacturing of sensor system components, when the measurement systems are designed and sensor components are selected to solve a specific measurement task, during application and later on during operation of the sensor system. The article provides a survey on important aspects that have to be considered for the use of reliable and long-term stable SHM systems, reflects upon state of the art of standards and guidelines activities, besides summarizing validation aspects that have to be described in FOS guidelines. Important technical aspects that influence sensor characteristics and the accuracy, efficiency, and long-term integrity of a sensor system are exemplified for fiber-optic strain sensors. One test method to characterize strain transfer for applied sensor fibers is discussed. Keywords: standards; guidelines; fiber-optic sensor; reliability; measurement uncertainty

Different experience from fibre sensor applications on-site has revealed the need of guidelines for developers, manufacturers, suppliers as well as users. Although best knowledge and well-founded experience are available in the fibre sensor community, a lack of technical instructions for all persons involved can lead to unreliable measurement results or even damage of sensing components. In contrast, manufacturing and application procedures according to generally binding technical rules will ensure long-term stable sensor systems and reliable measurement results. These rules have to include definitions of particular terms to describe the sensor and sensor system characteristics as well as methods to validate and use sensors properly. Because FBG sensors are the most popular sensing techniques in very different fields, important aspects to structure a set of technical recommendations will be discussed, especially for the use of FBG sensors in experimental stress analysis and for structure monitoring.

Assessment of ultimate bearing capacity and bearing behavior of large concrete piles in existing foundations or during and after installation remains a difficult task. A common and widespread test method is high-strain dynamic load testing using the one dimensional theory of wave propagation to calculate bearing capacity. Another method of quality insurance based on this theory is low-strain dynamic pile integrity testing. Both testing methods use sensors attached onto or near the pile head. In order to get more precise information about the pile response over whose length, highly resolving fiber optic sensors based on Fabry-Perot technology have been developed for integration into concrete piles at several levels. Motivation is the monitoring of pile deformations during dynamic low-strain, high-strain and static load testing with only one measuring device. First small scale piles have been tested in model tests. All signal responses from integrated sensors have been recorded and compared to signals obtained from common methods of instrumentation. The paper describes the sensing principle, sensor head installation as well as test results.

Standardization activities for fiber optic sensors are increasingly discussed in the scientific as well as users community. Although numerous standards for the characterization of fiber optic components have been available for years, guidelines or extensive standards for use of fiber optic sensors are still 'in statu nascendi'. Not only fiber sensor users are interested in getting guidelines and technical recommendations, manufacturers are also interested in getting technical standards for validation and specification. Development of standards for fiber optic sensors will be intrinsically very complex and thus different from standards for optical fibers and their components. They have to cover different physical mechanisms due to different sensor principles for a multitude of measurands, application fields, and types. The paper gives, first, a survey of recent international activities in this field. It will propose, second, a possible structure for fiber optic sensor characterization standards as well as a structure for guidelines needed for the most frequent practical applications. Special standardization issues to be included in discussion also concern: * choice and design aspects for sensors for mechanical quantities (particularly strain and deformation) * consideration of possible environmental and measurement-relevant circumstances on-site * proof test conditions * requirements on application techniques to bring the sensor system into service appropriately. The discussion in European and worldwide committees on fiber optic sensors that already exist or recently have started should cover all mentioned standardization aspects. Some problems with the establishing of manpower that is fully available for this extensive work are discussed.

Creation and development of long-term stable and reliable monitoring systems for large structures require the separate consideration of the relevant system components. The principle contributors: sensing element, cables/couplers, and sources/demodulation systems require very different reflection in regard to reliability and stability. Additionally, those aspects influence considerably the method of sensor application and its quality. The paper discusses the basic requirements on long-term monitoring systems, considers reliability aspects for different sensor application methods and provides important reliability aspects when fiber optic sensors are integrated into materials and structures. Emphasis is given on validation of measurement systems as a very important step for potential users and the use of a clear vocabulary when describing quality parameters of system components or entire monitoring systems.

Fiber Bragg grating sensor arrays can be used to monitor the mechanical behavior of rotor blades of wind turbines. In order to investigate how stable and reliably work such sensors, different fiber Bragg gratings were embedded into textilereinforced composite. Long-term temperature and tensile (fatigue) tests have been carried out with composite structure specimens. This paper reports on selected results of the tests and discusses important reliability aspects with regard to the fiber design and the fiber material.

Geotechnical measurements are producing various data which are used for interpretation and e.g. safety calculation. The reliability of such data is of most importance as every decision on civil engineering action needed is based on this data. Known and also unknown influences changing data are a basic demand for deeper investigation and research. In present time we have limited tools only to minimize perturbing influences. One of these demands-the long-term development of data also called long-term stability-is described in this paper. The paper describes a sensor head for long-term high-precision measurements of very small deflections of a diaphragm used for pressure gauges. High precision deformation measurement is assured by using a fiber Fabry-Perot interferometer sensor; identification of zero-point changes, and thus, long-term stable measurement is achieved by a specially designed absolute interferometer sensor. Several fiber optic solutions based on fiber Fabry-Perot technique have been investigated to find out a reliable sensor design. The presented sensor design has reached prototype status and allows to measure unambiguously static deformations with high precision. In order to evaluate repeatability and possible changes of zero-point reference if the head has been disconnected, validation of the described pressure gauge has been started. This validation work includes calibration and enables to evaluate possible drift effects, and to identify mechanical or thermal hysteresis. Thus, the highlight in this paper is the observation and measurement of zero-point development over time.

Commercially used fiber optic measurement methods have different performances because of different physical princi-ples and different sensor designs. Environmental influences, type of application and operational conditions can cause perturbations in the sensor system, depending on the chosen measurement principle. Such perturbations lead to faulty measurements, and thus, the structural behavior can be misinterpreted. In order to ensure reliable measurements, not only the characteristics of the sensor system must be known, but also its ability for the specific use must be proven. This paper points out essential criteria for optimum choice of fiber optic sensor systems and demonstrates necessary steps to evaluate the long-term stability and reliability of a sensor system. The paper summarizes the conditions required for evaluation of a sensor system, and briefly touches on the correct use of vocabulary of general terms in fiber sensor measurement technique to describe the real performance unambiguously. On the way towards drafting guidelines and standards for an appropriate use of fiber sensors, firstly survey of important issues is presented. Two details of these are explained with the example of FBG strain sensors. Finally, when fiber sensors are to be installed on-site, the procedure of validation is presented to assure that the particular requirements for a specific intended use of fiber sensors are fulfilled.

A new central railway station - Lehrter Bahnhof- is being built in Berlin. Because of construction activities in immediate vicinity and because of difficult soil conditions, vertical displacements will be expected. In order to avoid damage to the bridges and to a widely spanned glass roof which will be supported by two concrete bridges these two bridges have to be monitored right from the beginning of construction until commissioning as well as later on for several years. For this purpose, a long-term monitoring concept has been developed. Sensors with excellent long-term stability have been chosen to carry out the concept. This paper describes the measuring concept as well as components of the system. Especially techniques to monitor settlements and heaves (by means of laser-based optics and hydrostatic leveling components) and to measure strain and inclination of the prestressed concrete bridges (by embedded long-gage length fiber-optic strain sensors, resistive strain gages, and inclinometers) are described. All measures are redundantly monitored. Measurements on-site are referenced by measurements on two large-scale beam models well-defined loaded under laboratory and field conditions.

This paper summarizes the results of availability analysis completed for optical shared protection rings (OSPRs) applied to long-haul networks. Fault scenarios are described for the case of clients with automatic protection switching (APS) although results of the analysis are given for both clients with and without APS. It is shown that for clients with APS, OSPRs can provide avilability comparable to SONET/SDH rings.

The rapid evolution of terrestrial optical networks is driving the need for optical domain performance monitoring in order to provide the lowest transport cost per managed bit. This paper presents various techniques for monitoring optical signals between 3R interfaces in terms of their economic value to the network operator.

In a German slab track system (Feste Fahrbahn FF, system Boegl) for speeds up to 300 km/h and more different fiber optic sensors have been embedded in several levels and locations of the track system. The track system consists of prestressed precast panels of steel fiber concrete which are supported by a cat-in-situ concrete or asphalt base course. The sensors are to measure the bond behavior or the stress transfer in the track system. For that, tiny fiber-optic sensors - fiber Fabry-Perot and Bragg grating sensors - have been embedded very near to the interface of the layers. Measurements were taken on a full scale test sample (slab track panel of 6.45 m length) as well as on a real high speed track. The paper describes the measurement task and discusses aspects with regard to sensor design and prefabrication of the sensor frames as well as the embedding procedure into the concrete track. Results from static and dynamic full scale tests carried out in the testing laboratory of BAM and from measurements on a track are given.

A new central railway station - Lehrter Bahnhof - is being built in Berlin. Because of construction activities in immediate vicinity and because of difficult soil conditions, different vertical displacements have to be expected. In order to avoid damage to the bridges and to a widely spanned glass roof which will be supported by two concrete bridges these two bridges have to be monitored with regard to their deformation performance right from the beginning of construction until commissioning as well as later on for several years. For this purpose, a monitoring concept has been developed and sensors with excellent long-term stability have been chosen. This paper describes the system for monitoring settlements and heaves by means of laser-based optics and hydrostatic leveling. Additionally, strain and inclination of the prestressed concrete bridges are redundantly monitored by embedded long-gage length fiber-optic strain sensors as well as resistive strain gages, and inclinometers. Measurements on-site are referenced by measurements on two test beams well-defined loaded under laboratory and field conditions. The paper also describes the measuring concept and the sensor techniques as well as installation of the sensor system and first results.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Currently, fibre-optic sensors (FOSs) are commonly used if special requirements make the application of electrical sensors impossible, or economic benefit is promised. The scientific background of FOS technology is well developed; however, there are still some restrictions with respect to long-term reliable use. For widespread practical use, sensor products must be manufactured, characterized and validated according to standards. Guidelines on how to apply sensors and evaluate their operation on-site including special facilities to evaluate applied sensors are needed. This paper will focus on important aspects, such as when FOSs may be used under real practical conditions, and will present validation methodologies to evaluate the overall quality of the sensor system's function. It will also indicate the lack of knowledge and methods to be elaborated to promote the use of FOS.

The use of fiber optic sensors for measuring and monitoring tasks on structure components and large civil structures will only be successful if one is attentive to a nubmer of conditions in this raw environment. Most of the tasks require a direct contact of the sensor element to the measuring object without any protecting barrier. Such a contact may always entail mechanical damages to the sensor surface and chemical attacks on the primary coating.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Monitoring of the structure condition with the long-term goal of a `self-supervising' building presupposes sensor techniques which yield measuring information about the building characteristic and open up possibilities to detect beginning damage. This paper is to demonstrate the activities of the IEMB in Berlin for use of fiber optic sensors in order to get more efficient information about quality parameters of buildings and structure components. The necessary steps for a successful integration of fiber sensors into structures -- from lab experiments via tests on large parts of structures in the test hall to applications on real structures -- are described. The preconditions for a sensor design which is suitable for embedment into mortar bodies for construction-accompanying measurements as well as for a handable application on steel structures on-site are presented. Examples of applications of fiber optic sensors for experimental investigations on large elements, and for measurements during construction and on specially test loaded bridges are described.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Surface-applied fibre optic strain sensors were investigated using a unique validation facility equipped with application-independent optical reference systems. First, different adhesives for the sensor's application were analysed regarding their material properties. Measurements resulting from conventional measurement techniques, such as thermo-mechanical analysis and dynamic mechanical analysis, were compared with measurements resulting from digital image correlation, which has the advantage of being a non-contact technique. Second, fibre optic strain sensors were applied to test specimens with the selected adhesives. Their strain-transfer mechanism was analysed in comparison with conventional strain gauges. Relative movements between the applied sensor and the test specimen were visualized easily using optical reference methods, digital image correlation and electronic speckle pattern interferometry. Conventional strain gauges showed limited opportunities for an objective strain-transfer analysis because they are also affected by application conditions.

A single stage magnetically focused image converter, having a nickel mesh at its first accelerating electrode, was constructed. An S‐11 post‐oxidized photocathode was processed in this image tube. The imaging properties of this type of image converter have been studied under static and pulsed conditions. The output image resolution was studied as a function of the pulse duration or the switching on time. The effect of the application of a pulse to the photocathode or the control grid on the output image resolution is also mentioned. The ’S’ distortion and pincushion distortion under pulsed conditions is also briefly described. Applications of this image converter in spark gap photography, plasma diagnostics, and beam cross‐section photography of the 1.3 GeV synchrotron at Frascati are briefly mentioned.