Combination of GPS and RTS measurements for the monitoring of semi-static and dynamic motion of pedestrian bridge

GPS and accelerometers have been broadly used the last decade for the monitoring of flexible structures and bridges, while Robotic Total Station (RTS) has been successfully assessed for the monitoring of slow and dynamic motions. Further experimental studies have revealed specific drawbacks of the GPS (multipath, etc.) and RTS (clipping, etc.) monitoring techniques and how these can be surpassed by their combined use. In the current study, we assess the performance of the complementary use of GPS and RTS for the monitoring of the semi-static and dynamic displacement of a relatively rigid pedestrian bridge, with main modal frequency more than 1Hz. Two RTS and GPS receivers were synchronised monitoring the deflection of the two sides of the mid-span of the bridge, while pedestrians excited the bridge. Several excitations (walking, marching, jumping, etc.) were examined, causing semi-static and/or dynamic displacement of the bridge, and rotation of the deck, of different amplitude and frequencies. The analysis of the RTS and GPS time-series, which was based on spectral analysis and band-pass filtering of the time-series, resulted to low- and high-frequency component expressing the semi-static and dynamic displacement. Finally, the combination of the GPS and RTS time-series made possible the estimation of 1-4mm semi-static displacement, the 5-10mm dynamic displacement and the estimation of the main modal frequencies

Combination of GPS and RTS measurements for the monitoring of semi-static and dynamic motion of pedestrian bridge

GPS and accelerometers have been broadly used the last decade for the monitoring of flexible structures and bridges, while Robotic Total Station (RTS) has been successfully assessed for the monitoring of slow and dynamic motions. Further experimental studies have revealed specific drawbacks of the GPS (multipath, etc.) and RTS (clipping, etc.) monitoring techniques and how these can be surpassed by their combined use. In the current study, we assess the performance of the complementary use of GPS and RTS for the monitoring of the semi-static and dynamic displacement of a relatively rigid pedestrian bridge, with main modal frequency more than 1Hz. Two RTS and GPS receivers were synchronised monitoring the deflection of the two sides of the mid-span of the bridge, while pedestrians excited the bridge. Several excitations (walking, marching, jumping, etc.) were examined, causing semi-static and/or dynamic displacement of the bridge, and rotation of the deck, of different amplitude and frequencies. The analysis of the RTS and GPS time-series, which was based on spectral analysis and band-pass filtering of the time-series, resulted to low- and high-frequency component expressing the semi-static and dynamic displacement. Finally, the combination of the GPS and RTS time-series made possible the estimation of 1-4mm semi-static displacement, the 5-10mm dynamic displacement and the estimation of the main modal frequencies

Combination of GPS and RTS measurements for the monitoring of semi-static and dynamic motion of pedestrian bridge

GPS and accelerometers have been broadly used the last decade for the monitoring of flexible structures and bridges, while Robotic Total Station (RTS) has been successfully assessed for the monitoring of slow and dynamic motions. Further experimental studies have revealed specific drawbacks of the GPS (multipath, etc.) and RTS (clipping, etc.) monitoring techniques and how these can be surpassed by their combined use. In the current study, we assess the performance of the complementary use of GPS and RTS for the monitoring of the semi-static and dynamic displacement of a relatively rigid pedestrian bridge, with main modal frequency more than 1Hz. Two RTS and GPS receivers were synchronised monitoring the deflection of the two sides of the mid-span of the bridge, while pedestrians excited the bridge. Several excitations (walking, marching, jumping, etc.) were examined, causing semi-static and/or dynamic displacement of the bridge, and rotation of the deck, of different amplitude and frequencies. The analysis of the RTS and GPS time-series, which was based on spectral analysis and band-pass filtering of the time-series, resulted to low- and high-frequency component expressing the semi-static and dynamic displacement. Finally, the combination of the GPS and RTS time-series made possible the estimation of 1-4mm semi-static displacement, the 5-10mm dynamic displacement and the estimation of the main modal frequencies

Design and implementation of a new system for large bridge monitoring—GeoSHM

Structural Health Monitoring (SHM) is a relatively new branch of civil engineering that focuses on assessing the health status of infrastructure, such as long-span bridges. Using a broad range of in-situ monitoring instruments, the purpose of the SHM is to help engineers understand the behaviour of structures, ensuring their structural integrity and the safety of the public. Under the Integrated Applications Promotion (IAP) scheme of the European Space Agency (ESA), a feasibility study (FS) project that used the Global Navigation Satellite Systems (GNSS) and Earth Observation (EO) for Structural Health Monitoring of Long-span Bridges (GeoSHM) was initiated in 2013. The GeoSHM FS Project was led by University of Nottingham and the Forth Road Bridge (Scotland, UK), which is a 2.5 km long suspension bridge across the Firth of Forth connecting Edinburgh and the Northern part of Scotland, was selected as the test structure for the GeoSHM FS project. Initial results have shown the significant potential of the GNSS and EO technologies. With these successes, the FS project was further extended to the demonstration stage, which is called the GeoSHM Demo project where two other long-span bridges in China were included as test structures. Led by UbiPOS UK Ltd. (Nottingham, UK), a Nottingham Hi-tech company, this stage focuses on addressing limitations identified during the feasibility study and developing an innovative data strategy to process, store, and interpret monitoring data. This paper will present an overview of the motivation and challenges of the GeoSHM Demo Project, a description of the software and hardware architecture and a discussion of some primary results that were obtained in the last three years

FDG-PET/MRI for nonoperative management of rectal cancer: A prospective pilot study

Nonoperative management (NOM) is increasingly utilized for rectal cancer patients with a clinical complete response (cCR) following total neoadjuvant therapy (TNT). The objective of this pilot study was to determine whether FDG-PET/MRI alters clinical response assessments among stage I-III rectal cancer patients undergoing TNT followed by NOM, relative to MRI alone. This prospective study included 14 subjects with new rectal cancer diagnoses. Imaging consisted of FDG-PET/MRI for initial staging, post-TNT restaging, and surveillance during NOM. Two independent readers assessed treatment response on MRI followed by FDG-PET/MRI. Inter-reader differences were resolved by consensus review. The reference standard for post-TNT restaging consisted of surgical pathology or clinical follow-up. 7/14 subjects completed post-TNT restaging FDG-PET/MRIs. 5/7 subjects had evidence of residual disease and underwent total mesorectal excision; 2/7 subjects had initial cCR with no evidence of disease after 12 months of NOM. FDG-PET/MRI assessments of cCR status at post-TNT restaging had an accuracy of 100%, compared with 71% for MRI alone, as FDG-PET detected residual tumor in 2 more subjects. Inter-reader agreement for cCR status on FDG-PET/MRI was moderate (kappa, 0.56). FDG-PET provided added value in 82% (9/11) of restaging/surveillance scans. Our preliminary data indicate that FDG-PET/MRI can detect more residual disease after TNT than MRI alone, with the FDG-PET component providing added value in most restaging/surveillance scans

Bose-Einstein correlations of charged hadrons in proton-proton collisions at s\sqrt s = 13 TeV

Bose-Einstein correlations of charged hadrons are measured over a broad multiplicity range, from a few particles up to about 250 reconstructed charged hadrons in proton-proton collisions at $\sqrt{s}$ = 13 TeV. The results are based on data collected using the CMS detector at the LHC during runs with a special low-pileup configuration. Three analysis techniques with different degrees of dependence on simulations are used to remove the non-Bose-Einstein background from the correlation functions. All three methods give consistent results. The measured lengths of homogeneity are studied as functions of particle multiplicity as well as average pair transverse momentum and mass. The results are compared with data from both CMS and ATLAS at $\sqrt{s}$ = 7 TeV, as well as with theoretical predictions.[graphic not available: see fulltext]Bose-Einstein correlations of charged hadrons are measured over a broad multiplicity range, from a few particles up to about 250 reconstructed charged hadrons in proton-proton collisions at $\sqrt{s} =$ 13 TeV. The results are based on data collected using the CMS detector at the LHC during runs with a special low-pileup configuration. Three analysis techniques with different degrees of dependence on simulations are used to remove the non-Bose-Einstein background from the correlation functions. All three methods give consistent results. The measured lengths of homogeneity are studied as functions of particle multiplicity as well as average pair transverse momentum and mass. The results are compared with data from both CMS and ATLAS at $\sqrt{s} =$ 7 TeV, as well as with theoretical predictions

Search for dark matter in events with a leptoquark and missing transverse momentum in proton-proton collisions at 13 TeV

A search is presented for dark matter in proton-proton collisions at a center-of-mass energy of root s= 13 TeV using events with at least one high transverse momentum (p(T)) muon, at least one high-p(T) jet, and large missing transverse momentum. The data were collected with the CMS detector at the CERN LHC in 2016 and 2017, and correspond to an integrated luminosity of 77.4 fb(-1). In the examined scenario, a pair of scalar leptoquarks is assumed to be produced. One leptoquark decays to a muon and a jet while the other decays to dark matter and low-p(T) standard model particles. The signature for signal events would be significant missing transverse momentum from the dark matter in conjunction with a peak at the leptoquark mass in the invariant mass distribution of the highest p(T) muon and jet. The data are observed to be consistent with the background predicted by the standard model. For the first benchmark scenario considered, dark matter masses up to 500 GeV are excluded for leptoquark masses m(LQ) approximate to 1400 GeV, and up to 300 GeV for m(LQ) approximate to 1500 GeV. For the second benchmark scenario, dark matter masses up to 600 GeV are excluded for m(LQ) approximate to 1400 GeV. (C) 2019 The Author(s). Published by Elsevier B.V.Peer reviewe

Measurement of t(t)over-bar normalised multi-differential cross sections in pp collisions at root s=13 TeV, and simultaneous determination of the strong coupling strength, top quark pole mass, and parton distribution functions

Peer reviewe

Search for an L-mu - L-tau gauge boson using Z -> 4 mu events in proton-proton collisions at root s=13 TeV

A search for a narrow Z' gauge boson with a mass between 5 and 70 GeV resulting from an L-mu - L-tau U (1) local gauge symmetry is reported. Theories that predict such a particle have been proposed as an explanation of various experimental discrepancies, including the lack of a dark matter signal in direct-detection experiments, tension in the measurement of the anomalous magnetic moment of the muon, and reports of possible lepton flavor universality violation in B meson decays. A data sample of proton-proton collisions at a center-of-mass energy of 13 TeV is used, corresponding to an integrated luminosity of 77.3 fb(-1) recorded in 2016 and 2017 by the CMS detector at the LHC. Events containing four muons with an invariant mass near the standard model Z boson mass are analyzed, and the selection is further optimized to be sensitive to the events that may contain Z -> Z'mu mu -> 4 mu decays. The event yields are consistent with the standard model predictions. Upper limits of 10(-8)-10(-7) at 95% confidence level are set on the product of branching fractions B(Z -> Z'mu mu)B(Z' -> mu mu), depending on the Z' mass, which excludes a Z' boson coupling strength to muons above 0.004-0.3. These are the first dedicated limits on L-mu - L-tau models at the LHC and result in a significant increase in the excluded model parameter space. The results of this search may also be used to constrain the coupling strength of any light Z' gauge boson to muons. (C) 2019 The Author(s). Published by Elsevier B.V.Peer reviewe

An embedding technique to determine ττ backgrounds in proton-proton collision data

An embedding technique is presented to estimate standard model tau tau backgrounds from data with minimal simulation input. In the data, the muons are removed from reconstructed mu mu events and replaced with simulated tau leptons with the same kinematic properties. In this way, a set of hybrid events is obtained that does not rely on simulation except for the decay of the tau leptons. The challenges in describing the underlying event or the production of associated jets in the simulation are avoided. The technique described in this paper was developed for CMS. Its validation and the inherent uncertainties are also discussed. The demonstration of the performance of the technique is based on a sample of proton-proton collisions collected by CMS in 2017 at root s = 13 TeV corresponding to an integrated luminosity of 41.5 fb(-1).Peer reviewe