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- ItemAccess to a floating wind turbine(The Royal Institution of Naval Architects, 2017-03) Shanley, Matthew; Wright, Christopher S.; Otter, Aldert; Desmond, Cian J.; Murphy, Jimmy; The Royal Institution of Naval Architects; Lir National Ocean Test Facility, Ireland; Science Foundation IrelandThe offshore wind turbine service industry is now well established with a large number of turbines being successfully operated and maintained. A number of methods and technologies are available to allow the safe transfer of service crews to these primarily fixed monopile installations. The most common of these is the bow transfer method which uses a combination of a high friction fender and a large vessel thrust to minimise relative motion between the bow and the turbine foundation. An upcoming challenge for the offshore wind turbine service industry will be the increasing use of floating foundations in far offshore and deep water sites. A number of structures are currently being developed and the first commercial floating wind farm is expected to be commissioned in late 2017. The use of floating structures will make it more difficult to ensure crew safety and comfort during transfer operations as the interaction between two floating bodies needs to be considered. Thus, the bow transfer method used to access fixed foundations may not be suitable for accessing floating turbine platforms. This paper will use a combination of physical and numerical modelling to assess the ability of a wind farm service vessel to maintain contact with a floating offshore wind turbine structure by use of the bow transfer method.
- ItemApplication of S transform in structural health monitoring(2009) Pakrashi, Vikram; Ghosh, BidishaThe successful detection of change in a data or in any of its derivatives in the presence of noise is a critical component of structural health monitoring and damage detection. This sudden change can be brought about by a sudden change in the strain or the stress field of the structural system under consideration. Two very typical examples of such sudden changes are the sudden change in stiffness of a vibrating single degree of freedom system in time and the local perturbation of stress and strain fields of a beamlike structure in space due to the presence of an open crack. New methods and analysis techniques have become popular in the field of structural health monitoring to detect and characterise such changes. Time – frequency techniques, like wavelet analysis are being more widely used in this regard in the recent times for the detection of presence, location and the calibration of the extent of these changes. This paper presents the application of S transform for the successful detection and calibration of damage in time and in space in the presence of additive Gaussian white noise. The performance of S transform based detection is compared with wavelet based and statistics based methodologies. The application and use of S transform in the field of structural health monitoring is observed to be extremely promising.
- ItemArtificial neural network application in short-term prediction in an oscillating water column(The International Society of Offshore and Polar Engineers (ISOPE), 2010-01) Sheng, Wanan; Lewis, Anthony; Science Foundation Ireland; Department of Communications, Energy and Natural Resources, IrelandOscillating Water Column (OWC) is one type of promising wave energy devices due to its obvious advantage over many other wave energy converters: no moving component in sea water. Two types of OWCs (bottom-fixed and floating) have been widely investigated, and the bottom-fixed OWCs have been very successful in several practical applications. Recently, the proposal of massive wave energy production and the availability of wave energy have pushed OWC applications from near-shore to deeper water regions where floating OWCs are a better choice. For an OWC under sea waves, the air flow driving air turbine to generate electricity is a random process. In such a working condition, single design/operation point is nonexistent. To improve energy extraction, and to optimise the performance of the device, a system capable of controlling the air turbine rotation speed is desirable. To achieve that, this paper presents a short-term prediction of the random, process by an artificial neural network (ANN), which can provide near-future information for the control system. In this research, ANN is explored and tuned for a better prediction of the airflow (as well as the device motions for a wide application). It is found that, by carefully constructing ANN platform and optimizing the relevant parameters, ANN is capable of predicting the random process a few steps ahead of the real, time with a good accuracy. More importantly, the tuned ANN works for a large range of different types of random, process.
- ItemAutomatic UAV inspection of tunnel infrastructure in GPS-denied underground environment(Springer Nature Switzerland AG, 2022-06-16) Zhang, Ran; Ouyang, Aohui; Li, ZiliIn the Architecture, Engineering and Construction (AEC) industry, unmanned aerial vehicles (UAV) has been widely acknowledged as a promising tool to perform adaptive structural health monitoring automatically. However, there still remains some challenges for drones to collect image data of underground structures, primarily due to low light and no GPS conditions. In order to facilitate data acquisition, this article developed a mobile software development kit (MSDK) for drone using visual positioning and predefined controlling code, which enabled the drone to automatically fly along a designated sinusoidal route, whilst continuously taking videos and images of the tunnel surface. The developed MSDK was able to adjust the drone parameters (e.g., overlapping rate, inspection range, heading, flight direction between frames of the video) for different underground infrastructure conditions. Furthermore, a field test is conducted in an abandoned windless tunnel near Cork (Goggins Hill Tunnel) to test its feasibility. Results show that the 40-m difference between the designated routine and actual routine was 1.9%, and the collected data processed by Pix4Dmapper could reconstruct the complete tunnel scene and surface details. The navigation method proposed in this paper allows UAVs to perform automatic inspection without GPS, and the collected image data is used to build a tunnel panorama view.
- ItemBusiness modelling for smart continual commissioning in ESCO set-ups(Springer Verlag, 2017-08-22) Hryshchenko, Andriy; Menzel, Karsten; Seventh Framework ProgrammeThe availability of sensors, smart meters, and so called ‘intelligent devices’ (IoT) enables owners and tenants to better understand and flexibly adjust the status of buildings and their systems according to their needs. However, it also requires a more intense and detailed knowledge about how to exploit, analyse and manage ‘big data’ compiled from these devices. Building operators, facility managers and energy suppliers are expected to collaborate and to share this data aiming to deliver more holistic, comprehensive services to clients (i.e. owners and tenants of buildings). This paper discusses how so called ESCO-business models (energy service companies) and CC-business models (continuous commissioning) can be integrated through sharing of big data and collaboration of major stakeholders involved in building operation, energy supply and engineering consultancy. It explains how building owners will benefit from the availability of such comprehensive, collaborative services.
- ItemClimate change risk for Irish timber power pole networks(Seoul National University, 2019-05-26) Hawchar, Lara; Stewart, Mark G.; Nolan, Paul; Sweeney, Fergus; Ryan, Paraic C.; Environmental Protection AgencyThe latest IPCC report states that warming of the climate system is unequivocal, and this warming may lead to increased risk of breakdown of infrastructure networks due to extreme weather. Before appropriate action can be taken for power infrastructure in this regard, we must first understand existing risk, and then try to predict potential climate related changes in risk. The work described in this paper examines both existing vulnerability, and potential future vulnerability, for a notional network of Irish timber power poles. These power pole networks represent important critical infrastructure assets, both nationally, and internationally. There are currently approximately two million timber power poles in service in Ireland, five million timber power poles in service in Australia, worth over $10 billion, and approximately 200 million treated power poles in service in the United States. The impacts of climate change on Irish power poles will be examined herein using a Monte-Carlo event-based sequential model, which incorporates structural reliability, deterioration, climatic effects and network maintenance. The hazards of interest are storm winds and timber decay - both of which may worsen due to a changing climate.
- ItemDamage calibration of a beam using wavelet analysis and image processing(Bridge Engineering in Ireland, 2006) Pakrashi, Vikram; O'Connor, Alan J.; Basu, BiswajitEfficient damage detection and calibration of structures have gained great importance in recent times in terms of health monitoring and maintenance programmes. Wavelet analysis based damage detection and calibration from the deflected shape of beams are theoretically known to be a simple and efficient way of assessing damage. However, the measurement of the static or dynamic deflected shape of a vibrating beam is often difficult. The use of sophisticated devices to measure such spatial characteristics suffer from the disadvantage of high cost of the instrument and its unavailability. This paper considers a simply supported aluminium beam with an open crack and presents a video camera based inexpensive laboratory study to assess the damage using wavelet analysis. The vibrating deflected shape recorded by the camera has been processed using image processing methods and an intelligent pattern recognition procedure for the quantification of such the dynamic deflected shape at a particular instant of time. Wavelet analysis was subsequently performed on the damaged deflected shape to successfully identify the location of the damage and estimate the degree of damage for different crack depth ratios. The image analysis based detection is found to be a novel, easy and an inexpensive technique and the method is seen to have a potential for unmanned online structural health monitoring process.
- ItemDetection of pitting corrosion in steel using image processing(MEDACHS 2010, 2010-04-29) Ghosh, Bidisha; Pakrashi, Vikram; Schoefs, FranckThis paper presents an image processing based detection method for detecting pitting corrosion in steel structures. High Dynamic Range (HDR) imaging has been carried out in this regard to demonstrate the effectiveness of such relatively inexpensive techniques that are of immense benefit to Non – Destructive – Tesing (NDT) community. The pitting corrosion of a steel sample in marine environment is successfully detected in this paper using the proposed methodology. It is observed, that the proposed method has a definite potential to be applied to a wider range of applications.
- ItemDistributed fibre optic strain sensing of CERN infrastructures in the molasse region(Icelandic Geotechnical Society (IGS), 2019) Di Murro, V.; Soga, K.; Fern, E. J.; Pelecanos, L.; Li, Zili; Scibile, L.; CERN; Engineering and Physical Sciences Research Council; Innovate UKThe European Centre for Nuclear Research (CERN) is a large underground laboratory and it is home to two large particle accelerators, including the «Large Hadron Collider» (LHC). The particles travel at the speed of light through a series of tunnels which must comply with the high serviceability requirements. However, the underground facilities have expanded over a period of 40 years with new tunnels, shafts and caverns. Structural ageing and deterioration of the infrastructure can alter the drainage conditions around tunnels and this can cause, in turn, excess deformation of the tunnels and serviceability issue for the particle accelerators. A remote monitoring system based on distributed fibre-optic strain sensing technology has been implemented in some of the concrete-lined tunnels in order to gain insight in the long-term mechanical behaviour of the underground system. This paper presents the results of the monitoring programme and the results show a slow development of ovalisation of the tunnel over a period of three years.
- ItemEffect of chloride exposure condition on the performance of concretes containing PFA(Purdue University, 2018) Ryan, Paraic C.; O'Connor, Alan J.; Transport Infrastructure Ireland; Irish Research Council; European CommissionOver the past number of decades the use of different supplementary cementing materials have been investigated, with a view to increasing the resilience of reinforced concrete to chloride-induced corrosion. The slow nature of chloride-ion ingress has meant much of the information available on the relative performance of different concretes has been derived from accelerated testing, with the majority of these tests conducted under fully saturated conditions. While there is merit to such practices, there is also a need to examine the relative performance of different concretes under unsaturated conditions. This need is highlighted by the fact that reinforced concrete elements in the splash, spray and tidal zones of marine structures, which are subject to wetting and drying cycles, are most susceptible to reinforcement corrosion. This paper examines the effect of different wetting and drying cycles on the relative performance of OPC self-compacting concrete, and self-compacting concrete containing PFA. This was achieved through three sets of salt fog chamber tests, each with different wetting and drying cycles. It was found that, when compared to the OPC option, the relative chloride ingress resistance of the OPC + PFA concrete reduced when the degree of drying in the test increased. This indicates that fully saturated tests may somewhat overestimate the practical benefits of incorporating PFA into concrete in chloride rich environments.
- ItemThe effect of pore water pressure on structural performance of CERN concrete-lined tunnel(Civil Engineering Research Association of Ireland, 2020) Xiao, Zhipeng; Osborne, John Andrew; Perez-Duenas, Eliseo; Li, Zili; Ruane, Kieran; Jaksic, Vesna; Horizon 2020The European Centre for Nuclear research (CERN) operates the most powerful circular particle accelerator in a large-scale underground tunnel network of over 70 km. Even over four decades after construction, substantial cracks, water infiltration and structural deformation have still been developing with time based upon field observation and measurements. In particular, recent blockage of tunnel drainage system alters the hydraulic boundary condition and results in the development of pore-water pressure around the tunnel circumference, which in turn accelerates the tunnel deterioration and leakage. In this study, the development of pore water pressure and its effect on tunnel lining are investigated using 3D hydro-mechanical coupled finite element modelling. In the numerical simulation, particular emphasis is placed on the change of lining permeability and the drainage system with time. Results show that the pore water pressure on tunnel lining is significantly affected by the change of hydraulic condition, and consequently exacerbates the tunnel structural performance in the long term.
- ItemEffect of road quality in structural health monitoring under operational conditions(Civil Engineering Research Association of Ireland, 2012-09) Jaksic, Vesna; Pakrashi, Vikram; O'Connor, Alan J.; Irish Research Council for Science, Engineering and TechnologyThe effect of unevenness in a bridge deck for the purpose of Structural Health Monitoring (SHM) under operational conditions is studied in this paper. The moving vehicle is modelled as a single degree of freedom system traversing the damaged beam at a constant speed. The bridge is modelled as an Euler-Bernoulli beam with a breathing crack, simply supported at both ends. The breathing crack is treated as a nonlinear system with bilinear stiffness characteristics related to the opening and closing of crack. The unevenness in the bridge deck considered is modelled using road classification according to ISO 8606:1995(E). Numerical simulations are conducted considering the effects of changing road surface classes from class A - very good to class E - very poor. Cumulant based statistical parameters, based on a new algorithm are computed on stochastic responses of the damaged beam due to passages of the load in order to calibrate the damage. Possibilities of damage detection and calibration under benchmarked and non-benchmarked cases are considered. The findings of this paper are important for establishing the expectations from different types of road roughness on a bridge for damage detection purposes using bridge-vehicle interaction where the bridge does not need to be closed for monitoring.
- ItemEffects of damage models in probabilistic assessment of structures: An illustrative example(MEDACHS08, 2008) Pakrashi, Vikram; O'Connor, Alan J.; Breysse, DenysDeterioration modelling of structures has gained significant importance in recent times in relation with structural health monitoring, rehabilitation, maintenance and decision making process. The behaviour of any deteriorating structure (or a network of structures) is extremely important while considering failure as defined from the viewpoint of both the owner/manager and the engineer. Since there are epistemic and aleatory uncertainties associated with any such process, the ideas of failure and the damage model require a probabilistic treatment. The time dependence of damage propagation very often depends on the climate conditions. On the other hand, the definition of failure by the owner and by the engineer may have different focus. These uncertainties and conflicts directly affect the assessment, optimal assessment time, repair and maintenance strategies, associated cost and the final decision regarding a structure at any given point or period of time. The paper discusses how the choice of a deterioration model (even non-functional) of a structure can affect the decision making options regarding a structure based on a probabilistic material and structure independent general framework through a simple and illustrative example. A wooden beam damaged by the growth of fungus is considered to be the benchmark problem in this regard. The damage is modelled to be comprised of two stages – the initiation and the propagation period. A Monte Carlo simulation investigates the effects of environmental parameters, active regions in time, conflicts of owner’s and engineer’s criteria and the critical location in a structure in terms of possible destructive or non destructive instrumentation.
- ItemEffects of vehicle speed in structural health monitoring from operational conditions of bridges(CRC Press, Taylor & Francis Group, 2013-06) Jaksic, Vesna; O'Connor, Alan J.; Pakrashi, Vikram; Deodatis, George; Ellingwood, Bruce R.; Frangopol, Dan M.; Irish Research Council for Science, Engineering and TechnologyThe effects of vehicle speed for Structural Health Monitoring (SHM) of bridges under operational conditions are studied in this paper. The moving vehicle is modelled as a single degree oscillator traversing a damaged beam at a constant speed. The bridge is modelled as simply supported Euler-Bernoulli beam with a breathing crack. The breathing crack is treated as a nonlinear system with bilinear stiffness characteristics related to the opening and closing of crack. The unevenness of the bridge deck is modelled using road classification according to ISO 8606:1995(E). The stochastic description of the unevenness of the road surface is used as an aid to monitor the health of the structure in its operational condition. Numerical simulations are conducted considering the effects of changing vehicle speed with regards to cumulant based statistical damage detection parameters. The detection and calibration of damage at different levels is based on an algorithm dependent on responses of the damaged beam due to passages of the load. Possibilities of damage detection and calibration under benchmarked and non-benchmarked cases are considered. Sensitivity of calibration values is studied. The findings of this paper are important for establishing the expectations from different vehicle speeds on a bridge for damage detection purposes using bridge-vehicle interaction where the bridge does not need to be closed for monitoring. The identification of bunching of these speed ranges provides guidelines for using the methodology developed in the paper.
- ItemElectric vehicle: infrastructure regulatory requirements(Irish Transport Research Network, 2010-09) Foley, Aoife M.; Winning, Ian; Ó Gallachóir, Brian P.; Ghosh, Bidisha; Murray, Roisin; Environmental Protection AgencyIn 2009 the European Union (EU) Directive on Renewable Energy placed an obligation on each Member State to ensure that 10% of transport energy (excluding aviation and marine transport) come from renewable sources by 2020. The Irish Government intends to achieve part of this target by making sure that 10% of all vehicles in its transport fleet are powered by electricity by 2020. Stakeholder groups include but are not limited to policy makers, the public, regulatory bodies, participants in the electricity retail market, the transmission and distribution system grid operators, the automotive industry, private enterprise, civil engineers, electrical engineers, electricians, architects, builders, building owners, building developers, building managers, fleet managers and EV owners. Currently it appears both internationally and Nationally the automotive industry is focused on EV manufacture, governments and policy makers have highlighted the potential environmental and job creation opportunities while the electricity sector is preparing for an additional electrical load on the grid system. The focus of this paper is to produce an international EV roadmap. A review of current international best practice and guidelines under consideration or recommended is presented. An update on any EV infrastructure charging equipment standards is also provided. Finally the regulatory modifications to existing National legislation as well as additional infrastructure items which may need control via new regulations are identified.
- ItemEmergency rehabilitation of Brownsbarn bridge(2010) Pakrashi, Vikram; Kelly, Joe; Harkin, Julie; Farrell, Aidan; Nanukuttan, SreejithThis paper outlines the repair methodology of Brownsbarn Bridge situated over the N7 near Dublin. The repair strategy was formulated following impact damage to the soffit from a low- loader carrying an excavator passing underneath the bridge. Significant damage was observed to one of the beams. The repairs were carried out as emergency works over a bank holiday weekend in Ireland successfully. The rehabilitation methodology is based on preloading the bridge before repair followed by a removal of load to ensure the reestablishment of some of the lost prestress. This paper outlines the various stages of rehabilitation and establishes the timelines of significant events along with practical discussions on the execution of the rehabilitation methodology. The bridge was continuously monitored throughout the refurbishment process. This case study is expected to be of topical interest to researchers, practicing engineers, bridge owners and end-users alike.
- ItemEnergy harvesting for monitoring bridges over their operational life(NDT.net, 2016-07) Cahill, Paul; Hanley, Ciaran; Jaksic, Vesna; Mathewson, Alan; Pakrashi, Vikram; Irish Research Council; Science Foundation Ireland; Seventh Framework ProgrammeThe use of energy harvesting materials for large infrastructure is a promising and growing field. In this regard, the use of such harvesters for the purpose of structural health monitoring of bridges has been proposed in recent times as one of the feasible options since the deployment of them can remove the necessity of an external power source. This paper addresses the performance issue of such monitors over the life-cycle of a bridge as it deteriorates and the live load on the structure increases. In this regard, a Lead Zirconate Titanate (PZT) material is considered as the energy harvesting material and a comparison is carried out over the operational life of a reinforced concrete bridge. The evolution of annual average daily traffic (AADT) is taken into consideration, as is the degradation of the structure over time, due to the effects of corrosion. Evolution of such harvested energy is estimated over the life-cycle of the bridge and the sensitivity of harvested energy is investigated for varying rates of degradation and changes in AADT. The study allows for designing and understanding the potential of energy harvesters as a health monitor for bridges. This paper also illustrates how the natural growth of traffic on a bridge over time can accentuate the identification of damage, which is desirable for an ageing structure. The paper also assesses the impact and effects of deployment of harvesters in a bridge as a part of its design process, considering performance over the entire life-cycle versus a deployment at a certain age of the structure.
- ItemExperimental detection of sudden stiffness change in a structural system employing Laser Doppler Vibrometry(2012-06) Jaksic, Vesna; Pakrashi, Vikram; Basu, Biswajit; Ryan, Kevin; Irish Research Council for Science Engineering and TechnologySudden changes in the stiffness of a structure are often indicators of structural damage. Detection of such sudden stiffness change from the vibrations of structures is important for Structural Health Monitoring (SHM) and damage detection. Non-contact measurement of these vibrations is a quick and efficient way for successful detection of sudden stiffness change of a structure. In this paper, we demonstrate the capability of Laser Doppler Vibrometry to detect sudden stiffness change in a Single Degree Of Freedom (SDOF) oscillator within a laboratory environment. The dynamic response of the SDOF system was measured using a Polytec RSV-150 Remote Sensing Vibrometer. This instrument employs Laser Doppler Vibrometry for measuring dynamic response. Additionally, the vibration response of the SDOF system was measured through a MicroStrain G-Link Wireless Accelerometer mounted on the SDOF system. The stiffness of the SDOF system was experimentally determined through calibrated linear springs. The sudden change of stiffness was simulated by introducing the failure of a spring at a certain instant in time during a given period of forced vibration. The forced vibration on the SDOF system was in the form of a white noise input. The sudden change in stiffness was successfully detected through the measurements using Laser Doppler Vibrometry. This detection from optically obtained data was compared with a detection using data obtained from the wireless accelerometer. The potential of this technique is deemed important for a wide range of applications. The method is observed to be particularly suitable for rapid damage detection and health monitoring of structures under a model-free condition or where information related to the structure is not sufficient.
- ItemExperimental study on the wave measurements of wave buoys(International Conference on Ocean Energy, 2014-11) Liu, Qiulin; Lewis, Anthony; Zhang, Yongliang; Sheng, Wanan; National Natural Science Foundation of China; National High Technology Research and Development Program, China; State Key Laboratory of Hydroscience and Engineering, ChinaWave measurement is of vital importance for assessing the wave power resources and for developing wave energy devices, especially for the wave energy production and the survivability of the wave energy device. Wave buoys are one of the most popular measuring technologies developed and used for long-term wave measurements. In order to figure out whether the wave characteristics can be recorded by using the wave buoys accurately, an experimental study was carried out on the performance of three wave buoy models, viz two WaveScan buoys and one ODAS buoy, in a wave tank using the European FP7 MARINET facilities. This paper presents the test results in both time and frequency domains and the comparison between the wave buoys and wave gauge measurements. The analysis results reveal that for both regular and irregular waves, the WaveScan buoys have better performances than the ODAS buoy in terms of accuracy and the WaveScan buoys measurements have a very good correlation with those from the wave gauges.
- ItemFrom M&V to M&T: An artificial intelligence-based framework for real-time performance verification of demand-side energy savings(Institute of Electrical and Electronics Engineers (IEEE), 2018-09) Gallagher, Colm V.; O'Donovan, Peter; Leahy, Kevin; Bruton, Ken; O'Sullivan, Dominic T. J.; Science Foundation IrelandThe European Union's Energy Efficiency Directive is placing an increased focus on the measurement and verification (M&V) of demand side energy savings. The objective of M&V is to quantify energy savings with minimum uncertainty. M&V is currently undergoing a transition to practices, known as M&V 2.0, that employ automated advanced analytics to verify performance. This offers the opportunity to effectively manage the transition from short-term M&V to long-term monitoring and targeting (M&T) in industrial facilities. The original contribution of this paper consists of a novel, robust and technology agnostic framework that not only satisfies the requirements of M&V 2.0, but also bridges the gap between M&V and M&T by ensuring persistence of savings. The approach features a unique machine learning-based energy modelling methodology, model deployment and an exception reporting system that ensures early identification of performance degradation. A case study demonstrates the effectiveness of the approach. Savings from a real-world project are found to be 177,962 +/- 12,334 kWh with a 90% confidence interval. The uncertainty associated with the savings is 8.6% of the allowable uncertainty, thus highlighting the viability of the framework as a reliable and effective tool.