Installation Of Monitoring System Research Articles

Continuous dynamic monitoring of an onshore wind turbine

Current utility-scale wind turbines are highly dynamic systems excited by a large variety of loading sources. The proper operation of wind turbines thus requires a complete knowledge of the actual dynamic behavior of the system, in order to ensure the expected longevity of their main structural elements. In that context, this paper describes the monitoring project developed for a 2.0 MW wind turbine, the description of the installed monitoring system, as well as the main steps included in the methodology developed for the continuous processing of the collected data. The main results achieved during one year of monitoring are shown in detail. They allowed to accurately characterize the variability of the dynamic properties of the wind turbine, with special emphasis on the natural frequencies and damping ratios of the most important vibration modes, throughout normal operating conditions of the turbine. In addition, several shutdown events were identified and used to estimate the modal damping of the wind turbine through the analysis of free-decay responses of the structure. This monitoring project contributes to improve the knowledge on the dynamic behavior of onshore wind turbines under normal operating conditions.

High Resolution Monitoring Above and Below the Groundwater Table Uncovers Small-Scale Hydrochemical Gradients.

Hydrochemical solute concentrations in the shallow subsurface can be spatially highly variable within small scales, particularly at interfaces. However, most monitoring systems fail to capture these small scale variations. Within this study, we developed a high resolution multilevel well (HR-MLW) with which we monitored water across the interface of the unsaturated and saturated zone with a vertical resolution of 0.05-0.5 m. We installed three of these 4 m deep HR-MLWs in the riparian zone of a third-order river and analyzed for hydrochemical parameters and stable water isotopes. The results showed three distinct vertical zones (unsaturated zone, upper saturated zone, lower saturated zone) within the alluvial aquifer. A 2 m thick layer influenced by river water (upper saturated zone) was not captured by existing monitoring wells with higher screen length. Hydrochemical data (isotopes, total ions) were consistent in all HR-MLWs and showed similar variation over time emphasizing the reliability of the installed monitoring system. Further, the depths zones were also reflected in the NO3-N concentrations; with high spatial variabilities between the three wells. The zonation was constant over time, with seasonal variability in the upper saturated zone due to the influence of river water. This study highlights the use of high resolution monitoring for identifying the spatial and temporal variability of hydrochemical parameters present in many aquifer systems. Possible applications range from riparian zones, agricultural field sites to contaminated site studies, wherever an improved understanding of biogeochemical turnover processes is necessary.

Efficient generation of receiver operating characteristics for the evaluation of damage detection in practical structural health monitoring applications.

Permanently installed guided wave monitoring systems are attractive for monitoring large structures. By frequently interrogating the test structure over a long period of time, such systems have the potential to detect defects much earlier than with conventional one-off inspection, and reduce the time and labour cost involved. However, for the systems to be accepted under real operational conditions, their damage detection performance needs to be evaluated in these practical settings. The receiver operating characteristic (ROC) is an established performance metric for one-off inspections, but the generation of the ROC requires many test structures with realistic damage growth at different locations and different environmental conditions, and this is often impractical. In this paper, we propose an evaluation framework using experimental data collected over multiple environmental cycles on an undamaged structure with synthetic damage signatures added by superposition. Recent advances in computation power enable examples covering a wide range of practical scenarios to be generated, and for multiple cases of each scenario to be tested so that the statistics of the performance can be evaluated. The proposed methodology has been demonstrated using data collected from a laboratory pipe specimen over many temperature cycles, superposed with damage signatures predicted for a flat-bottom hole growing at different rates at various locations. Three damage detection schemes, conventional baseline subtraction, singular value decomposition (SVD) and independent component analysis (ICA), have been evaluated. It has been shown that in all cases, the component methods perform significantly better than the residual method, with ICA generally the better of the two. The results have been validated using experimental data monitoring a pipe in which a flat-bottom hole was drilled and enlarged over successive temperature cycles. The methodology can be used to evaluate the performance of an installed monitoring system and to show whether it is capable of detecting particular damage growth at any given location. It will enable monitoring results to be evaluated rigorously and will be valuable in the development of safety cases.

Neural network-based data-driven modelling of anomaly detection in thermal power plant

ABSTRACTThe thermal power plant systems are one of the most complex dynamical systems which must function properly all the time with least amount of costs. More sophisticated monitoring systems with early detection of failures and abnormal behaviour of the power plants are required. The detection of anomalies in historical data using machine learning techniques can lead to system health monitoring. The goal of the research is to build a neural network-based data-driven model that will be used for anomaly detection in selected sections of thermal power plant. Selected sections are Steam Superheaters and Steam Drum. Inputs for neural networks are some of the most important process variables of these sections. All of the inputs are observable from installed monitoring system of thermal power plant, and their anomaly/normal behaviour is recognized by operator's experiences. The results of applying three different types of neural networks (MLP, recurrent and probabilistic) to solve the problem of anomaly detection confirm that neural network-based data-driven modelling has potential to be integrated in real-time health monitoring system of thermal power plant.

Mining induced collapse in 1997 and seismic records at Changyu, SE China

Quarry induced collapse, an issue of particular concern in the mining industry, is a typical form of manmade disaster. Identification of the morphological characteristics of such collapses is commonly based on seismic records but comprehensive studies regarding the mechanism and energy conversion mode utilizing the seismic record is seldom undertaken. A huge collapse event at the Biyutan mining cavern at Changyu Dongtian in Wenling city, China, lasting for about 20 seconds, was observed on August 11, 1997. After the collapse, nearly 11 million m 3 of rock blocks were left on the floor. By conducting a field survey on engineering geology, retrospectively analyzing the collapsing process through interviewing local residents, referring to related documents, and identifying the seismic records obtained from 3 surrounding seismic stations, it was established the roof collapse at the Biyutan cavern, excavated in massive tuff, was due to over excavation of several pillars, which substantially affected the stress field in cavern roof giving rise to a local failure of the roof that gradually developing into a widespread failure in an area EW 800m long, SN 460m wide. During the collapse, outbursts of water and air shock waves result in loss of life and property within a distance of 150m from the mine opening. This reminds us that reasonable allocation of sufficiently strong safety pillars and installation of monitoring system are absolutely essential in quarrying operations to avoid overall failure and ensure the safety of the people nearby.

Assessment of water consumptions in small mediterranean islands\u2019 primary schools by means of a long-term online monitoring

A key challenge of our society is improving schools through the sustainable use of resources especially in countries at risk of desertification. The estimation of water consumption is the starting point for the correct dimensioning of water recovery systems. To date, unlike the energy sector, there is a lack of scientific information regarding water consumption in school buildings. Available data refer roughly to indirect estimates by means of utility bills and therefore no information on the role of water leakage in the internal network of the school is provided. In this context, the aim of the work was to define and implement an on-line monitoring system for the assessment of water consumptions in a small Mediterranean island primary school to achieve the following sub-goals: (1) definition of water consumption profile considering teaching activities and secretarial work; (2) direct assessment of water consumptions and leakages and, (3) quantification of the behaviour parameters. The installed monitoring system consisted of 33 water metres (3.24 persons per water metre) equipped with sensors set on 1-L impulse signal and connected to a data logging system. Results showed consumptions in the range 13.6–14.2 L/student/day and leakage equal to 54.8 % of the total water consumptions. Considering the behavioural parameters, the consumptions related to toilet flushing, personal, and building cleaning were, respectively, 54, 43 and 3 % of the total water ones. Finally, the obtained results could be used for dimensioning the most suitable water recovery strategies at school level such as grey water or rainwater recovery systems.

Energy performance gap in refurbished German dwellings: Lesson learned from a field test

Low insulation standards and obsolete heating systems of a large amount of buildings in Europe account for disproportional energy consumption. Within this project, the holistic renovation and the results from the monitoring activity of buildings from a field test, located in Southern Germany, are presented. The buildings, built at the end of the 1950s, have been retrofitted with seven different refurbishment layouts. The layouts differ in insulation and engineering system. An installed monitoring system collects thermal indoor environmental conditions and air quality conditions in rooms, as well as data about energy flows at delivery, distribution, storage and generation level, at high time resolution. The monitoring system allows a comparison between the real and the expected energy consumption of the buildings. The energy performance gap was identified and quantified for each refurbishment solution (with values up to 287% based on calculated savings): on average, the energy performance gap of the entire field test varied from 117% in 2011, 107% in 2012, 41% in 2013 and 60% in 2014. The occupants’ behavior has been identified as one of the causes for the energy performance gap. Further causes are mistakes in the installation, and malfunctioning of the engineering system. The importance of a monitoring system for buildings with a complex engineering system was confirmed.

Estimation of Unrecorded Alcohol Consumption in Low-, Middle-, and High-Income Economies for 2010.

Consumption of unrecorded alcohol is prevalent, especially in low-income countries (LIC). Monitoring and reduction of unrecorded consumption have been asked for in the World Health Organization (WHO) global strategy to reduce the harmful use of alcohol. To date, only a few countries have installed monitoring systems, however. As part of the WHO global monitoring, an expert survey using the nominal group technique, a variant of Delphi studies, was conducted to assess level and characteristics of unrecorded consumption in 46 member states. One hundred experts responded. Descriptive statistics and repeated analysis of covariance were used to analyze the data. The study showed feasibility of the chosen methodology to elicit information of unrecorded consumption with experts responding for 74% of the countries. Response rate was lower for LIC. Compared to prior WHO estimates, experts tended to estimate higher unrecorded consumption for LIC, and lower unrecorded consumption for high-income countries. Unrecorded consumption was seen as a financial, public health, and social problem by the majority of experts. Homemade alcohol was the most prevalent subcategory of unrecorded consumption globally. The chosen methodology was feasible, and new information about consumption of unrecorded consumption could be gathered. There is still a need for increasing efforts of national monitoring, especially in LIC.

Astrometric observations of visual binaries using 26-inch refractor during 2007–2014 at Pulkovo

We present the results of 15184 astrometric observations of 322 visual binaries carried out in 2007–2014 at Pulkovo observatory. In 2007, the 26-inch refractor (F = 10413 mm, D = 65 cm) was equipped with the CCD camera FLI ProLine 09000 (FOV 12′ × 12′, 3056 × 3056 pixels, 0.238 arcsec pixel−1). Telescope automation and weather monitoring system installation allowed us to increase the number of observations significantly. Visual binary and multiple systems with an angular distance in the interval 1.ʺ1–78.ʺ6 with 7.ʺ3 on average were included in the observing program. The results were studied in detail for systematic errors using calibration star pairs. There was no detected dependence of errors on temperature, pressure, and hour angle. The dependence of the 26-inch refractor’s scale on temperature was taken into account in calculations. The accuracy of measurement of a single CCD image is in the range of 0.ʺ0005 to 0.ʺ289, 0.ʺ021 on average along both coordinates. Mean errors in annual average values of angular distance and position angle are equal to 0.ʺ005 and 0.°04 respectively. The results are available here http://izmccd.puldb.ru/vds.htmand in the Strasbourg Astronomical Data Center (CDS). In the catalog, the separations and position angles per night of observation and annual average as well as errors for all the values and standard deviations of a single observation are presented. We present the results of comparison of 50 pairs of stars with known orbital solutions with ephemerides.

Analysing RMS and peak values of vibration signals for condition monitoring of wind turbine gearboxes

Wind turbines (WTs) are designed to operate under extreme environmental conditions. This means that extreme and varying loads experienced by WT components need to be accounted for as well as gaining access to wind farms (WFs) at different times of the year. Condition monitoring (CM) is used by WF owners to assess WT health by detecting gearbox failures and planning for operations and maintenance (O&M). However, there are several challenges and limitations with commercially available CM technologies – ranging from the cost of installing monitoring systems to the ability to detect faults accurately. This study seeks to address some of these challenges by developing novel techniques for fault detection using the RMS and Extreme (peak) values of vibration signals. The proposed techniques are based on three models (signal correlation, extreme vibration, and RMS intensity) and have been validated with a time domain data driven approach using CM data of operational WTs. The findings of this study show that monitoring RMS and Extreme values serves as a leading indicator for early detection of faults using Extreme value theory, giving WF owners time to schedule O&M. Furthermore, it also indicates that the prediction accuracy of each CM technique depends on the physics of failure. This suggests that an approach which incorporates the strengths of multiple techniques is needed for holistic health assessment of WT components.

Accuracy of an autocalibrated pulse contour analysis in cardiac surgery patients: a bi-center clinical trial.

BackgroundLess-invasive and easy to install monitoring systems for continuous estimation of cardiac index (CI) have gained increasing interest, especially in cardiac surgery patients who often exhibit abrupt haemodynamic changes. The aim of the present study was to compare the accuracy of CI by a new semi-invasive monitoring system with transpulmonary thermodilution before and after cardiopulmonary bypass (CPB).MethodsSixty-five patients (41 Germany, 24 Spain) scheduled for elective coronary surgery were studied before and after CPB, respectively. Measurements included CI obtained by transpulmonary thermodilution (CITPTD) and autocalibrated semi-invasive pulse contour analysis (CIPFX). Percentage changes of CI were also calculated.ResultsThere was only a poor correlation between CITPTD and CIPFX both before (r2 = 0.34, p < 0.0001) and after (r2 = 0.31, p < 0.0001) CPB, with a percentage error (PE) of 62 and 49 %, respectively. Four quadrant plots revealed a concordance rate over 90 % indicating an acceptable correlation of trends between CITPTD and CIPFX before (concordance: 93 %) and after (concordance: 94 %) CPB. In contrast, polar plot analysis showed poor trending before and an acceptable trending ability of changes in CI after CPB.ConclusionsSemi-invasive CI by autocalibrated pulse contour analysis showed a poor ability to estimate CI compared with transpulmonary thermodilution. Furthermore, the new semi-invasive device revealed an acceptable trending ability for haemodynamic changes only after CPB.Trial registrationClinicalTrials.gov: NCT02312505 Date: 12.03.2012

Comparison of Visual Inspection and Structural-Health Monitoring As Bridge Condition Assessment Methods

This paper presents the results of a research project aimed at examining the capabilities and challenges of two distinct but not mutually exclusive approaches to in-service bridge assessment: visual inspection and installed monitoring systems. In this study, the intended functionality of both approaches was evaluated on its ability to identify potential structural damage and to provide decision-making support. Inspection and monitoring are compared in terms of their functional performance, cost, and barriers (real and perceived) to implementation. Both methods have strengths and weaknesses across the metrics analyzed, and it is likely that a hybrid evaluation technique that adopts both approaches will optimize efficiency of condition assessment and ultimately lead to better decision making.

An Operator’s Perspective on Benefits and Challenges of In-Well Monitoring

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper OTC 25085, “In-Well Monitoring for Deepwater Wells—Operator’s View,” by Sandeep Patni, SPE, Shell, and Dennis Dria, SPE, Myden Energy Consulting, prepared for the 2014 Offshore Technology Conference, Houston, 5–8 May. The paper has not been peer reviewed. In-well monitoring can improve the quality of surveillance in subsea wells, enabling low-cost, nonintrusive well and reservoir surveillance, provided that the industry overcomes the technical challenges and gaps and improves the reliability of the system. However, significant challenges remain in the selection, qualification, and deployment of these technologies in deepwater subsea wells. This paper provides an operator’s viewpoint of in-well monitoring, covering some of the key challenges. Defining Monitoring-System Value The interest in downhole monitoring has been well-documented, and much effort and money have been spent to obtain such information as needed to evaluate reservoir potential, optimize operations and production, and manage cost and risk. The primary measurement historically has been single-point downhole pressure and temperature. The value of additional measurements, such as production logging, downhole sampling, and compaction logging, is high, but they require well intervention. Permanently installed monitoring systems, distributed multipoint sensors in particular, provide unique real-time, on-demand information. General methods using coupled temperature-/pressure-transient interpretations offer unique information not previously attainable if the sensing systems are available, be they electrical or optical. Useful measurements cover a broad range of applications and include the following: Gas lift monitoring/optimization Electrical-submersible-pump optimization Production/inflow monitoring Injection profiling Water management Well- and completion-integrity monitoring Compaction monitoring Fracture-height monitoring Real-time stimulation monitoring Sand detection

Challenges in field monitoring of energy performance of air conditioners

Experimental work could be conducted in either laboratory or at field site. Generally, the laboratory experiments are carried out in an artificial setting and with a highly controlled environment. By contrast, the field experiments often take place in a natural setting, subject to the influences of many uncontrolled factors. Therefore, it is necessary to carefully assess the possible limitations and appropriateness of an experiment before embarking on it. In this paper, a case study of field monitoring of the energy performance of air conditioners is presented. Significant challenges facing the experimental work are described. Lessons learnt from this case study are also discussed. In particular, it was found that ongoing analysis of the monitoring data and the correction of abnormal issues are two of the keys for a successful field test program. It was also shown that the installation of monitoring systems could have a significant impact on the accuracy of the data being collected. Before monitoring system was set up to collect monitoring data, it is recommended that an initial analysis of sample monitored data should be conducted to make sure that the monitoring data can achieve the expected precision. In the case where inevitable inherent errors were induced from the installation of field monitoring systems, appropriate remediation may need to be developed and implemented for the improved accuracy of the estimation of results. Ongoing analysis of monitoring data and correction of any abnormal issues would be the key to a successful field test program.

Performance Study of an Eight-story Steel Building Equipped with Oil Dampers Damaged During the 2011 Great East Japan Earthquake Part 1: Structural Identification and Damage Reasoning

Oil dampers installed on the first floor of an eight-story steel building were completely destroyed during the 2011 Great East Japan Earthquake. It is believed to be the first time in the world that real oil dampers in service failed due to earthquakes. Before this failure event, the actual performance of buildings that use oil dampers during catastrophic earthquakes has never been verified. Investigating the cause of the damage of the oil dampers is thus necessary and urgent. In this paper, a comprehensive identification was conducted to rebuild the numerical model of this damped structure equipped with/without damaged oil dampers using the measurement data of the installed monitoring system. Furthermore, the damage process of the oil dampers was postulated based on the identification and simulation results. The limit states of the oil dampers were studied. Based on the damages of the dampers and connection, the oil dampers experienced the displacement limit state when the allowable displacement limit was surpassed and the central cylinder pushed against the abutment. The insufficient stroke limit is the main cause of the collision between the damper and the abutment on the floor, which finally led to the failure of the oil dampers.

Continuous dynamic monitoring of a centenary iron bridge for structural modification assessment

A multi-channel continuous dynamic monitoring system has been installed in a centenary iron arch bridge on late November 2011. The historic infrastructure, completed in 1889 and crossing the Adda river about 50 km far from Milan, is the most important monument of XIX century iron architecture in Italy and is still used as roadway and railway bridge. The monitoring project follows a series of preliminary ambient vibration tests carried out on the bridge since June 2009. The paper describes the bridge structure and its dynamic characteristics identified from the experimental studies developed since 2009, the installed monitoring system and the software developed in LabVIEW for automatically processing the collected data. Subsequently, the tracking of automatically identified natural frequencies over a period of about 18 months is presented and discussed, highlighting the effects of environmental and operational conditions on the bridge dynamic characteristics as well as the detection of structural changes, mainly based on natural frequencies shifts.

Modern means of monitoring the hydrological regime in the Siret River Basin (Romania)

The hydrometrical monitoring of the water courses represents a major step in apprehending the hydrological regime. The old systems of monitoring imposed - in special circumstances – great efforts from operators, who sometimes reached exhaustion. For example, a flood in the lower basin of the Siret River extends on a period of even more than a week; meanwhile the gauging station observer must provide recorded data at least three to three hours. Lately new monitoring programs have been introduced to cover both classical gauging stations, and especially automatic stations which are already installed in the field. DESWAT Project (Destructive Water) which was conducted with the financial and technical support of USAID (United States Agency for Investment and Development) and USTDA (U.S. Trade and Development Agency) aims to elaborate appropriate recommendations in the field of flood protection, including public information, and modernization of hydrological monitoring network in the Siret River Basin, using the latest technology. Siret Water Administration has currently 82 automatic gauging stations and 35 independent automatic rainfall stations from the DESWAT project. The information collected by the automatic stations represents basic elements for the hydrological forecasting program RFS (River Forecast System). As a result of the project "Plan for Prevention, Protection and Mitigation of floods in the Siret River Basin" (Part I) there were obtained hydrological risk maps for the Siret River and its main tributaries, so that in Part II of the same project to be obtained risk maps for the smaller tributaries. As result of the project, Siret Water Administration also benefited of the hydrologic modelling software ISIS necessary to adjust and update the maps. The EASTAVERT Project will be implemented by the partner institutions for water management in Romania, Ukraine and Moldova, and aims to reduce the vulnerability to flooding of the communities in the border regions by carrying out upgrading works at the hydrological complex Stanca-Costesti, improving the warning system by installing monitoring systems in the Siret and Prut River Basins and increasing the responsiveness of the population through information.

Analysis of Structural Health Monitoring Data from Hammersmith Flyover

AbstractThere has recently been considerable research published on the applicability of monitoring systems for improving civil infrastructure management decisions. Less research has been published on the challenges in interpreting the collected data to provide useful information for engineering decision makers. This paper describes some installed monitoring systems on the Hammersmith Flyover, a major bridge located in central London (United Kingdom). The original goals of the deployments were to evaluate the performance of systems for monitoring prestressing tendon wire breaks and to assess the performance of the bearings supporting the bridge piers because visual inspections had indicated evidence of deterioration in both. This paper aims to show that value can be derived from detailed analysis of measurements from a number of different sensors, including acoustic emission monitors, strain, temperature and displacement gauges. Two structural monitoring systems are described, a wired system installed by a...

Assessment and Management of Concrete Bridges Supported by Monitoring Data-Based Finite-Element Modeling

The long-term assessment of large and complex civil infrastructures, such as prestressed concrete bridges, based on Finite Element (FE) modelling remains a challenging task. The construction process, the influence of erection methods, the characterization of concrete properties, geometric accuracy and environmental conditions are key factors involved in the development of robust FE models. Data collected using permanently installed monitoring systems is the most reliable strategy to improve such assessments. Indeed, the availability of monitoring data is increasingly being used in the validation of design assumptions, updating of FE models and safety factors. In this work, the long-term behaviour of a long segmental bridge built in Portugal − Leziria Bridge − is evaluated using FE model-updating. The combination of several factors, including: (i) the bridge’s scale, (ii) the monitoring database, (iii) the comprehensive scanning of important characteristics of the bridge and (iv) the FE modelling approach, makes this case study unique. Although the sensor trends are satisfactorily predicted, extrapolation of shrinkage and creep models, the influence of interior and exterior environments and thickness variations of the structural elements are identified as areas for further research.

Optimizing groundwater monitoring systems for landfills with random leaks under heterogeneous subsurface conditions

Landfills are one of the most common human activities threatening the natural groundwater quality. The landfill may leak, and the corresponding plumes may contaminate an area, entailing costly remediation measures. The objective of the installation of monitoring systems at landfill sites is to detect the contaminant plumes before they reach the regulatory compliance boundary in order to enable cost-effective counter measures. In this study, a classical decision analysis approach is linked to a stochastic simulation model to determine the optimal groundwater monitoring system given uncertainties due to the hydrogeological conditions and contaminant source characteristics. A Monte Carlo approach is used to incorporate uncertainties. Hydraulic conductivity and the leak location are the random inputs of the simulation model. The design objectives are to: (1) maximize the detection probability, (2) minimize the area of contamination at the time of detection, and (3) minimize the total cost of the monitoring system. A synthetic test case based on a real-world case in the Netherlands is analyzed. The results show that monitoring systems located close to the source are optimal except for the cases with very high unit installation and sampling cost and/or very cheap unit remediation.