Pervasive Fibre-optic sensor networks in bridges: A UK case study

© 2018 Taylor & Francis Group, London. Integrating fibre-optic sensor networks in a newly-constructed infrastructure assets enables datadriven performance assessment during its construction and throughout its operational life. As part of a multimillion pound railway infrastructure redevelopment project, two new railway bridges were instrumented with an extensive network of both discrete (fibre Bragg gratings or FBGs) and distributed (based on Brillouin optical time domain reflectometry or BOTDR) fibre optic sensors to measure both strain and temperature throughout construction and in-service. Completed in 2016 in Staffordshire UK, both ‘self-sensing’ bridges contain more than 500 fibre Bragg grating sensors and over 600 metres of distributed fibre optic sensor cabling. This paper describes the sensing technologies employed, installation techniques for improving sensing robustness, the monitoring programme and objectives, data processing methods and assumptions, and the primary monitoring findings of this project. Results related to measurements of prestress losses in prestressed concrete girders, estimates of steel girder deflection using FBGs and videogrammetry, and assessments of percentage utilization of critical superstructure elements are presented. In terms of future directions, BIM-based environments which incorporate sensor elements and an emerging field of research known as Data-Centric Engineering are introduced as tools to better manage, maintain and learn from the information generated from self-sensing infrastructure.EPSRC, Innovate UK and the Lloyd's Register Foundation for funding this research through the Centre for Smart Infrastructure and Construction (CSIC) Innovation and Knowledge Centre and the Alan Turing Institute

Integrated fibre-optic sensor networks as tools for monitoring strain development in bridges during construction

Long-term asset management and maintenance of civil infrastructure relies on having access to reliable performance data in order to inform critical decision-making processes. This paper discusses the development and implementation of a robust, innovative and highly distributed fibre-optic sensor network for use as a bridge monitoring and performance evaluation tool. The main steel girders of a new 26.8 metre span half-through steel railway bridge were each instrumented with 80 fibre Bragg grating (FBG) based sensors (spaced at 1 metre) prior to the casting of the concrete deck. Two major challenges with implementing fibre-optic monitoring systems remain prominent: appropriately compensating for strain changes due to temperature, and designing the system to be sufficiently robust to survive installation and continuous long-term operation. This study addresses these challenges through the implementation of a new temperature compensation sensor cable packaging and the deployment of glass-fibre reinforced strain FBG sensor cables with the aim of improving overall network reliability. The completed system is capable of measuring the dynamic strain of all installed FBG sensors simultaneously at sampling rates of 250 Hz to strain resolutions within ±10 microstrain. Data was collected and initial results are presented for the strain developed within the main girders during the casting and curing of the concrete deck. The sensor readings captured the quasi-distributed profile of strains developed along the main girders due to the casting and curing of the concrete deck and have provided insights into understanding the complex thermal response of the structure. This study demonstrates that integrated structural health monitoring systems installed at the time of construction can provide a complete record of the entire load history of a structure. Performance data of this type is invaluable for understanding the behaviour of composite concrete decks, evaluating future structural capacity, establishing long term monitoring programmes, and allowing performance-based asset management decision making

Novel Identification of LYVE-1 Positive Macrophages in Rheumatoid Synovial Tissue

Objective: LYVE-1+ macrophages are observed in a range of cancers, where they play a role in tumour lymphangiogenesis. In rheumatoid arthritis (RA), lymphangiogenesis increases in the early stage of the disease and decreases as it progresses, potentially exacerbating inflammatory cell persistence. We investigated whether LYVE-1+ macrophages were present in RA synovium. Methods: Synovial tissue from RA patients was obtained at joint replacement surgery and immunohistochemistry was performed to visualise LYVE-1+ and CD68+ cells. Results: LYVE-1+ macrophages were present in rheumatoid synovial tissue, the first observation of this kind. Conclusion: Despite the reduction in lymphangiogenesis in chronic RA, LYVE-1 positive macrophages are present and there is a potential role for macrophages in the generation of lymphatic vessels

Implementing bridge model updating for operation and maintenance purposes: examination based on UK practitioners’ views

There has been a vision of creating bridge digital twins as virtual simulation models of bridge assets to facilitate remote management. Bridge model updating is one digital twin technology which can enable the continuous updating of the structural model as new monitoring data is collected. This paper examines why there is currently little industry uptake of monitoring, modelling and model updating for the operation and maintenance of bridges despite over two decades of research in these fields. The study analyses the findings from a series of semi-structured industry interviews with expert bridge professionals in the U.K. and from an extensive literature survey of bridge model updating studies to examine the disconnects between research and practice and the practical issues of implementing bridge model updating. In particular, the study found that localised damage resulting in local reduction in structural stiffness, a key assumption made in the majority of research, is subject to question by practitioners as many common types of bridge damage may not induce noticeable change in structural stiffness that existing model updating techniques would identify. Key recommendations for future research are proposed to drive adoption of bridge monitoring, modelling and model updating and thus realise their industrial value

Evaluating the early-age behaviour of full-scale prestressed concrete beams using distributed and discrete fibre optic sensors

This paper evaluates the results of a monitoring study that captures the early age behaviour of four 11.9 m prestressed concrete bridge beams utilising both distributed and discrete fibre optic sensor (FOS) arrays. The performance of the beams is evaluated before they are placed in-service as part of new concrete railway bridges in the Midlands in the UK. Two types of prestressed beams were monitored, two TY7 internal beams and two TYE7 edge beams. The beams incorporated high strength (up to 90.7 MPa) self-consolidating concrete. The entire manufacturing process which included early-age curing and the detensioning process was captured in great detail using the installed FOS system. An analysis of the curing strains within the beams revealed the significant effect that ambient temperature, curing duration, and formwork restraint has on the development of prestress losses prior to detensioning. Based on the distributed FOS readings, it was observed that the strain remained uniform along the length of the beams during the various beam monitoring stages. The measured strain data was then used to calculate prestress losses in the first six months after casting (prior to casting of the in-situ concrete bridge deck). The TY7 and TYE7 beams experienced losses that were 79% and 72% of the ultimate losses predicted using Eurocode 2 equations, respectively. Distributed strain measurements were used to provide estimates of the change in beam camber with time. The pre-camber values calculated using the recorded FOS strain data at the time of detensioning closely match the theoretically calculated values. However, camber values increased by up to 1.7 times in the first six months compared with the post-detensioning values and deviated significantly from the theoretically calculated values. The future aim of this research is to establish integrated FOS systems as viable tools for monitoring strain evolution in concrete bridges in order to establish comprehensive baselines to facilitate long term data-driven bridge monitoring programmes.The authors gratefully acknowledge the EPSRC and Innovate UK for funding this research through the CSIC Innovation and Knowledge Centre (EPSRC grant reference number EP/L010917/1)

Management of structural monitoring data of bridges using BIM

In addition to the traditional benefits that are associated with the installation of structural health monitoring systems, reductions in construction, operational, and maintenance costs and improved performance and quality can be achieved by effectively using the acquired data. However, considered in isolation, the raw data is of little use and value. It needs to be processed and put into a geometric context within the infrastructure asset, which facilitates the interpretation and analysis of the data. This supports informed decision making that leads to effective actions. This study outlines a new approach that enables to model structural performance monitoring systems in a BIM environment and hence permits visualising sensor data directly on BIM models. The paper addresses aspects related to (i) interoperability and standard data models, (ii) management and visualisation of monitoring data, and (iii) data interpretation and analysis. A prestressed concrete bridge, with a comprehensive built-in structural performance monitoring system, has been used as a case study. The case study demonstrates that by including and visualising monitoring data directly on BIM models, the acquired data gains geometrical context within the built asset, which facilitates better interpretation, analysis, and all the data-sharing benefits associated with the BIM approach.Engineering and Physical Sciences Research Council, Innovate UK (CSIC Innovation and Knowledge Centre (Grant ID: EP/L010917/1)

Current measurement by real-time counting of single electrons

The fact that electrical current is carried by individual charges has been known for over 100 years, yet this discreteness has not been directly observed so far. Almost all current measurements involve measuring the voltage drop across a resistor, using Ohm's law, in which the discrete nature of charge does not come into play. However, by sending a direct current through a microelectronic circuit with a chain of islands connected by small tunnel junctions, the individual electrons can be observed one by one. The quantum mechanical tunnelling of single charges in this one-dimensional array is time correlated, and consequently the detected signal has the average frequency f=I/e, where I is the current and e is the electron charge. Here we report a direct observation of these time-correlated single-electron tunnelling oscillations, and show electron counting in the range 5 fA-1 pA. This represents a fundamentally new way to measure extremely small currents, without offset or drift. Moreover, our current measurement, which is based on electron counting, is self-calibrated, as the measured frequency is related to the current only by a natural constant.Comment: 9 pages, 4 figures; v2: minor revisions, 2 refs added, words added to title, typos correcte

Combination of gefitinib and methotrexate to treat tubal ectopic pregnancy (GEM3): a multicentre, randomised, double-blind, placebo-controlled trial

BACKGROUND: Tubal ectopic pregnancies can cause substantial morbidity or even death. Current treatment is with methotrexate or surgery. Methotrexate treatment fails in approximately 30% of women who subsequently require rescue surgery. Gefitinib, an epidermal growth factor receptor inhibitor, might improve the effects of methotrexate. We assessed the efficacy of oral gefitinib with methotrexate, versus methotrexate alone, to treat tubal ectopic pregnancy. METHODS: We performed a multicentre, randomised, double-blind, placebo-controlled trial across 50 UK hospitals. Participants diagnosed with tubal ectopic pregnancy were administered a single dose of intramuscular methotrexate (50 mg/m2) and randomised (1:1 ratio) to 7 days of additional oral gefitinib (250 mg daily) or placebo. The primary outcome, analysed by intention to treat, was surgical intervention to resolve the ectopic pregnancy. Secondary outcomes included time to resolution of ectopic pregnancy and serious adverse events. This trial is registered at the ISRCTN registry, ISCRTN 67795930. FINDINGS: Between Nov 2, 2016, and Oct 6, 2021, 328 participants were allocated to methotrexate and gefitinib (n=165) or methotrexate and placebo (n=163). Three participants in the placebo group withdrew. Surgical intervention occurred in 50 (30%) of 165 participants in the gefitinib group and in 47 (29%) of 160 participants in the placebo group (adjusted risk ratio 1·15, 95% CI 0·85 to 1·58; adjusted risk difference -0·01, 95% CI -0·10 to 0·09; p=0·37). Without surgical intervention, median time to resolution was 28·0 days in the gefitinib group and 28·0 days in the placebo group (subdistribution hazard ratio 1·03, 95% CI 0·75 to 1·40). Serious adverse events occurred in five (3%) of 165 participants in the gefitinib group and in six (4%) of 162 participants in the placebo group. Diarrhoea and rash were more common in the gefitinib group. INTERPRETATION: In women with a tubal ectopic pregnancy, adding oral gefitinib to parenteral methotrexate does not offer clinical benefit over methotrexate and increases minor adverse reactions. FUNDING: National Institute of Health Research

Airway smooth muscle as a target of asthma therapy: history and new directions

Ultimately, asthma is a disease characterized by constriction of airway smooth muscle (ASM). The earliest approach to the treatment of asthma comprised the use of xanthines and anti-cholinergics with the later introduction of anti-histamines and anti-leukotrienes. Agents directed at ion channels on the smooth muscle membrane (Ca(2+ )channel blockers, K(+ )channel openers) have been tried and found to be ineffective. Functional antagonists, which modulate intracellular signalling pathways within the smooth muscle (β-agonists and phosphodiesterase inhibitors), have been used for decades with success, but are not universally effective and patients continue to suffer with exacerbations of asthma using these drugs. During the past several decades, research energies have been directed into developing therapies to treat airway inflammation, but there have been no substantial advances in asthma therapies targeting the ASM. In this manuscript, excitation-contraction coupling in ASM is addressed, highlighting the current treatment of asthma while proposing several new directions that may prove helpful in the management of this disease

Micro-pharmacokinetics: quantifying local drug concentration at live cell membranes

Fundamental equations for determining pharmacological parameters, such as the binding afnity of a ligand for its target receptor, assume a homogeneous distribution of ligand, with concentrations in the immediate vicinity of the receptor being the same as those in the bulk aqueous phase. It is, however, known that drugs are able to interact directly with the plasma membrane, potentially increasing local ligand concentrations around the receptor. We have previously reported an infuence of ligand-phospholipid interactions on ligand binding kinetics at the β2-adrenoceptor, which resulted in distinct “micro-pharmacokinetic” ligand profles. Here, we directly quantifed the local concentration of BODIPY630/650-PEG8-S-propranolol (BY-propranolol), a fuorescent derivative of the classical β-blocker propranolol, at various distances above membranes of single living cells using fuorescence correlation spectroscopy. We show for the frst time a signifcantly increased ligand concentration immediatel adjacent to the cell membrane compared to the bulk aqueous phase. We further show a clear role of both the cell membrane and the β2-adrenoceptor in determining high local BY-propranolol concentrations at the cell surface. These data suggest that the true binding afnity of BY-propranolol for the β2-adrenoceptor is likely far lower than previously reported and highlights the critical importance of understanding the “micro-pharmacokinetic” profles of ligands for membrane-associated proteins