Online Monitoring Data Research Articles

Influence of ambient temperature on the fatigue damage of welded bridge decks

Fatigue life assessment of critical bridge members using online monitoring data has been investigated in recent years. To make an efficient evaluation, a representative block of cycles is usually defined. However, relatively small amount of data in the representative block sometimes fail to cover the change caused by temperature and increasing traffic flow, which are proved by this paper to be important regarding fatigue damage. To find the relationship between fatigue damage, temperature and increasing traffic flow, an equivalent vehicle load method is presented. The statistical disposition of traffic flow and finite element analysis have been conducted, using data from the Runyang Suspension Bridge as an example. Then the damage caused by increasing traffic flow can be estimated and eliminated from the total damage so that the temperature effect is finally obtained. It is observed that temperature has a linear effect on the fatigue damage of welded joints of bridge decks within the temperature range from −4.31 °C to 46.95 °C. Possible reasons for this temperature effect have been discussed.

Structural assessment under uncertain parameters via interval analysis

An efficient health monitoring system for damage detection in civil engineering structures using on-line monitoring data is being developed to identify any possible damage in short time. The present work is based on the treatment of uncertainties, which is one of the basic common difficulties faced when modelling structures. A methodology, based on interval analysis (IA) theory [R.E. Moore, Interval Analysis, Prentice-Hall, Englewood Cliffs, NJ, 1966] applied to a numerical constraint satisfaction problem (CSP) [J.R. Casas, J.C. Matos, J.A. Figueiras, J. Vehí, O. García, P. Herrero, Bridge monitoring and assessment under uncertainty via interval analysis, in: Ninth International Conference On Structural Safety And Reliability—ICOSSAR2005, 2005. pp. 487–494], is implemented in the damage detection [J.R. Casas, J.C. Matos, J.A. Figueiras, J. Vehí, O. García, P. Herrero, Bridge monitoring and assessment under uncertainty via interval analysis, in: Ninth International Conference On Structural Safety And Reliability—ICOSSAR2005, 2005. pp. 487–494] and modelling system of a long-term monitoring project in order to achieve such an objective. An algorithm is being developed for using such methodology with the obtained data. Such methodology has been first checked in the laboratory with a simple reinforced concrete structure (loaded up to failure). The obtained results are useful for identifying the load where the structure presents changes in its behaviour. The majority of the structures present a linear elastic behaviour throughout their life. However, they tend to deteriorate; such degradation reflects on results obtained from the long term monitoring system. Structural assessment was successfully performed in this case, enabling its application to real structures.

Multi-scale numerical analysis on dynamic response and local damage in long-span bridges

This paper aims to develop an approach for multi-scale numerical analysis on structural dynamic response and local damage in long-span bridges. The strategies of finite element modeling of long-span bridges for multi-scale numerical analysis was first investigated. A multi-scale model of the Tsing Ma Bridge (TMB) was then developed based on the design drawings and proposed strategies for multi-scale modeling. The procedures for multi-scale numerical analysis on the dynamic response and local damage are proposed, in which local deterioration processes at welded details of interconnects are able to account for the major effect of the damage and nonlinear influence on structural response. The multi-scale computations are implemented based on the software ABAQUS and the developed programs via the user interface provided by the software for the purpose of easier application to large civil structures. The accuracy of the calculated procedures is addressed with two smaller controlled examples before the approach can be applied to the Tsing Ma Bridge. Based on the online monitoring data acquired from the Structural Health Monitoring (SHM) system installed on TMB, the global dynamic response of the bridge and local damage accumulation of two typical weld details in the longitudinal truss of TMB under traffic loading are numerically analyzed by using the developed model and computational procedures. The maximum value of the accumulated damage is found on the toe of the weld of the upper and/or bottom chords with the diagonal and gusset plate intersection. The fatigue life obtained from the fully coupled calculation is smaller than that from the uncoupled computation, which suggests that the significant interaction between the damage and the structural response should be considered in the structural damage analyses using the multi-scale numerical computation.

On-Line NDE and Structural Health Monitoring for Advanced Reactors

This paper considers the use of on-line structural health monitoring in advanced nuclear power systems such as IRIS. The motivation for the on-line health monitoring is to prevent routine maintenance from interrupting long-term continuous reactor operation. However, the outcome of the on-line monitoring implementation has a broader impact, and amounts to a paradigm shift in maintenance strategy from outage-based maintenance to continuous real-time monitoring of operational and structural integrity. Indeed, on-line health monitoring data will provide a foundation for diagnostics and prognostics (i.e., predictive) capabilities that will detect component degradation prior to failure, thus allowing for proactive rather than reactive maintenance strategies. Specifically, this paper briefly reports on our studies on (1) on-line monitoring strategy and its benefits, (2) candidate reactor components where on-line monitoring provides maximum benefits, (3) applicable on-line NDE sensor methodologies and conceptual sensor designs, and (4) model-based sensor performance estimations.

On-line Monitoring of Wastewater True Color Using Digital Image Analysis and Artificial Neural Network

The American Dye Manufactures’ Institute (ADMI) 3 and 31 wavelength (WL) methods are the most well-known analytical methods for measuring wastewater true color. However, these two methods use a spectrophotometer as the measurement device. The measurements thus must be conducted in the laboratory and cannot provide on-line monitoring data for process control. This study applies the digital image analysis (DIA) method to develop an effective and economical method for on-line monitoring of the wastewater true color. The DIA method was used to measure three types of colored samples including the platinum-cobalt color standard solutions, synthetic colored samples and real colored samples. Experimental results show that the DIA method performed not only with good accuracy and precision but also high sensitivity in the measurement of true color. However, the DIA values present different linear relationship with the ADMI 3 and 31 WL values for different sample hues. Direct substitutions of DIA, ADMI 3 and 31 WL v...

Mechanical systems hazard estimation using condition monitoring

The ability to predict hazards of mechanical systems accurately can significantly enhance the predictive maintenance task. However, predicting hazards of systems accurately is non-trivial, especially when historical failure data are sparse or zero. The proposed proportional covariate model (PCM) overcomes this difficulty. This paper describes the concepts of PCM briefly and focuses on the estimation of the hazards of mechanical systems using accelerated life tests and condition monitoring data. This new approach to hazard estimation can reduce the number of accelerated life tests significantly. The hazard estimation can further be refined and updated with on-line condition monitoring data on a continual basis.

Online monitoring system and data management for KamLAND

In January 22, 2002, KamLAND started the data-taking. The KamLAND detector is a complicated system which consists of liquid scintillator, buffer oil, spherical balloon and so on. In order to maintain the detector safety, we constructed monitoring system which collected detector status information such as balloon weight, liquid scintillator oil level and so on. In addition, we constructed continuous Rn monitoring system for the 7Be solar neutrino detection. The KamLAND monitoring system consists of various network, LON, 1-Wire, and TCP/IP, and these are indispensable for continuous experimental data acquisition.

Monitoring of structures and environment when constructing Lefortovo Tunnel in Moscow

The construction of the largest municipal highway tunnel in Russia intended for passing 3800 cars per hour in three lanes was completed in December, 2003. The tunnel is the last link closing the Moscow Third Transport Ring. The tunnel total length is 3.3 km. The construction of the main tunnel section of 2222 m long has been carried out within the national preserve zone ''Lefortovo - Nemetskaya sloboda'' where the historical monuments - buildings of the 18th century and fountains with ponds are located in the vast park zone. The construction has been accomplished in the complicated geological conditions with use of the Herrenknecht bentonite tunnel boring machine with an external diameter of 14.2 m as well as the lining made of high-accuracy reinforced concrete segments with two rows of waterproofing seals. For the shallow embedded structures the lining of frame reinforced concrete elements with film insulation has been erected in excavations with ''ground wall'' protection strengthened with prestressed anchor bolts and locally supplemented with steel braces. Tunnel construction has been carried out with continuous monitoring of stresses and strains in structures, quality of filling the clearance between the lining and the ground with grouting mortar, alteration of ground water conditions, deformations of buildings and communications located within the construction area. For that purpose special gauges, geodetic and geophysical research methods and ground water observation holes have been used. By the results of the tunnelling starting stage the previously developed methods of tunnel lining analysis, prediction of ground massif deformations and specifying the tunnel face thrust pressure have been corrected. Particularly, the measurements inside the tunnel have revealed a certain reserve of the lining bearing capacity and showed that during advancing the shield influence upon the lining pressure has been showed along a length of about 100 m. The accepted construction method and work management as well as on-line monitoring data (correct prediction, preliminary detection of non-documented communications and purposeful, according to the prediction, ground consolidation in the foundation of separate structures including compensation grouting) have provided tunnelling during 1 year with an average advance of 8 m per day without accidents and emergencies and disturbance of urban environment with the minimum values of surface settlements (from 2 to 12 mm) providing invariability of the ground water level. (A). Reprinted with permission from Elsevier. For the covering abstract see ITRD E124500.

A concept of online monitoring for the Wendelstein 7-X experiment

Abstract Steady state operation of the Wendelstein 7-X fusion experiment makes it indispensable to visualize a representative portion of the measured data online. A three tier concept for online data monitoring is introduced and focused upon four main points: • the generation of representative raw monitoring data within a data acquisition tier without disturbing the data acquisition • the online analysis of all raw monitoring data by a monitor server tier including the synchronization of data from different sources • the visualization of the monitoring data by a monitor client tier for local and remote participation • the communication between the participating tiers The current prototypic implementation is presented and the techniques used as well as the benefits achieved are discussed.

Robust signal extraction for on-line monitoring data

Data from the automatic monitoring of intensive care patients exhibits trends, outliers, and level changes as well as periods of relative constancy. All this is overlaid with a high level of noise and there are dependencies between the different items measured. Current monitoring systems tend to deliver too many false warnings which reduces their acceptability by medical staff. The challenge is to develop a method which allows a fast and reliable denoising of the data and which can separate artefacts from clinical relevant structural changes in the patients condition (Estadistica 53 (2001) 259). A simple median filter works well as long as there is no substantial trend in the data but improvements may be possible by approximating the data by a local linear trend. As a first step in this programme, the paper examines the relative merits of the L 1 regression, the repeated median (Biometrika 68 (1982) 242) and the least median of squares (Bull. Internat. Statist. Inst. 46 (1975) 375; J. Amer. Statist. Assoc. 79 (1984) 871). The question of dependency between different items is a topic for future research.

The Effects of Age, Ability, and Memory Monitoring on Prospective Memory Task Performance

In this study we examined the influences of age, ability, and monitoring on event-based prospective memory performance. Two samples of younger and older adults who differed in educational attainment and verbal ability were compared. Monitoring of the prospective task was measured through use of an on-line thought probe. Results yielded comparable prospective memory performance for the age/ability groups. On-line monitoring responses revealed a higher frequency of task-irrelevant thoughts among younger adults compared to older adults. However, on-line monitoring data were not related to prospective memory performance. Recognition memory was the strongest predictor of successful prospective memory, followed by working memory. These findings and their implications for current conceptions of prospective memory aging are discussed.

Fatigue analysis and life prediction of bridges with structural health monitoring data — Part I: methodology and strategy

This paper is aimed at developing a methodology and strategy for fatigue damage assessment and life prediction of bridge-deck sections of existing bridges with online structural health monitoring data. A fatigue damage model based on the continuum damage mechanics (CDM) is developed for evaluating accumulative fatigue damage of existing bridges. A structural model for the fatigue stress analysis of bridge-deck structures is proposed, in which structures are modeled by elastic members and welded connections with possible accumulative damage. Based on the proposed model, an analytical approach for evaluating the fatigue damage and service life of bridge-deck sections based on strain history data from an online structural health monitoring system and the CDM fatigue model are suggested. The updating of the representative block of cycles of the local stress by online monitoring data in the future is included in the computational approach. In order to compare results of fatigue damage and service life prediction evaluated by the CDM fatigue damage model, a modified Palmgren–Miner rule is developed for the same fatigue problem.

MET-RODOS: A Comprehensive Atmospheric Dispersion Module

A comprehensive meteorological dispersion module called MET-RODOS is being developed to serve the real-time RODOS decision support system with an integrated prediction capability for airborne radioactive spread, deposition and gamma radiation exposure on all scales. Deposition, ground level air concentrations, and ground level gamma dose rates from up to 15 simultaneous released nuclides are calculated using a nested system of local and long range atmospheric dispersion models, driven by real-time available on-line meteorological information. The MET-RODOS module uses concurrently the available source term and weather information in the RODOS data base system, and returns, up to +36h forecasts of nuclei-specific air and deposited concentrations including gamma dose rate estimations for display and subsequent processing within the RODOS framework. Weather and meteorology is available to the system via on-line connections to on-site local meteorological observations (met-towers and sodars) and via network (either public domain Internet or user-owed point-to-point ISDN) connections to remote national or international meteorological forecasting services. In its final form, scheduled for operational use in 1999, the MET-RODOS meteorological module is intended to service the RODOS system with actual and forecast (+36h) nuclei-specific air concentrations, deposition values, and gamma radiation estimates on the local, national, and European scale. provisions are furthermore being made for accommodating on-line available radiological monitoring data in the meteorological model chains in order for the module to assist with source term determination based on real-time data assimilation and back-fitting procedures.

The European Union Radiological Data Exchange Platform (EURDEP): Two Years of International Data Exchange Experience

Following a workshop (Arona, 1-3 June 1994) on the 'Technical Aspects of Intemational Exchange of Radiological On-line Monitoring data', a study was started to test the feasibility of exchanging automatic monitoring data between the fifteen EU Member States, Norway, Switzerland and the JRC-Ispra. Currently the underlying measurement network consists of existing monitoring stations in twelve countries from where information is exchanged on a weekly basis. In the longer term it will include all 17 above mentioned countries and will be extended to Eastern Europe. In a second workshop (Arona, 19-21 June 1996) the experience gained in the data exchange has been discussed, as well as the use of other communication protocols and the expansion of the system to participants in Eastern Europe. The practical experience gained during this feasibility study and the outcomes of the last workshop are reported.

A multi-parameter system for acquisition, monitoring, and analysis of scanning ion microprobe data

The multi-parameter data-acquisition system for the Eindhoven scanning ion microprobe set-up is described. The front-end part of the system is based on an M68030 in VME and handles real-time data acquisition, experiment control and data transport. It is linked to a DEC ALPHA-AXP workstation for data storage, on-line data monitoring and data analysis and off-line data analysis. The system can be used to apply simultaneously the micro-PIXE, NBS and NFS techniques to determine elemental concentration distributions on biomedical samples, but can also be used for coincident ion scattering experiments and time or dose dependent studies of e.g. ion-beam induced radiation damage.

Online Monitoring of Biological Reactions at Low Parts-Per-Trillion Levels by Membrane Inlet Mass Spectrometry

A flow-through membrane inlet combined with a single quadrupole mass spectrometer has been used for the direct on-line monitoring of biological reactions at the extremely low parts-per-trillion level. Linear signals over at least 4 orders of magnitude were obtained. As an example, on-line monitoring data from the microbial oxygenation of chloroethylenes in pure cultures of the methanotrophic bacteria Methylococcus capsulatus (Bath) are presented

Structural Material Anomaly Detection System Using Water Chemistry Data

The concept of an advanced water chemistry diagnosis system for detection of anomalies and preventive maintenance of system components is proposed and put into a concrete form. Using the analogy to a medical inspection system, analyses of water chemistry change will make it possible to detect symptoms of anomalies in system components. Then, correlations between water chemistry change and anomaly occurrence in the components of the BWR primary cooling system are analyzed theoretically. These fragmentary correlations are organized and reduced to an algorithm for the on-line diagnosis system using on-line monitoring data, pH and conductivity. By using actual plant data, the on-line diagnosis model system is verified to be applicable for early and automatic finding of the anomaly cause and for timely supply of much diagnostic information to plant operators.

Structural Material Anomaly Detection System Using Water Chemistry Data.

The concept of an advanced water chemistry diagnosis system for detection of anomalies and preventive maintenance of system components is proposed and put into a concrete form. Using the analogy to a medical inspection system, analyses of water chemistry change will make it possible to detect symptoms of anomalies in system components. Then, correlations between water chemistry change and anomaly occurrence in the components of the BWR primary cooling system are analyzed theoretically. These fragmentary correlations are organized and reduced to an algorithm for the on-line diagnosis system using on-line monitoring data, pH and conductivity. By using actual plant data, the on-line diagnosis model system is verified to be applicable for early and automatic finding of the anomaly cause and for timely supply of much diagnostic information to plant operators.

Development of an expert system for haemodynamic monitoring: computerized symbolization of on-line monitoring data

The development of intelligent alarm systems for intensive care benefits from the transformation of data from a quantitative to a qualitative mode. We constructed a computerized algorithm for the symbolization of on-line monitoring data of heart rate, systemic arterial, pulmonary arterial and central venous pressures, as well as central and peripheral temperatures. We tested the ability of the algorithm to symbolize the levels of the parameters and to detect significant long-term trends in ten adult patients admitted to the intensive care unit after cardiac surgery. The estimations of an experienced clinician were taken as the 'gold standard'. The symbolization of the levels of the monitored parameters was in agreement with the clinician in 99.4% of the estimations. The algorithm detected 93.0% of the trends correctly and also estimated their reliability. The clinician considered its estimations to be accurate in 96.2% of cases. On the other hand, the clinician considered unreliable 2.4% of all the trends detected and classified as reliable by the algorithm. The computerized algorithm for the symbolization of real-time monitoring data performed efficiently enough for its further use in expert systems for intelligent monitoring.

The dynamics of the continuous emulsion polymerization of methylmethacrylate

AbstractExperimental data on the dynamics of the continuous emulsion polymerization of methylmethacrylate are presented. Techniques for on‐line reaction monitoring and digital data acquisition as reported previously are used to generate dynamic data on the monomer conversion and free emulsifier concentration. Data are reported confirming the existence of multiple steady states and limit cycles in the CSTR (continuous stirred tank reactor) emulsion polymerization of methylmethacrylate. Data are also reported suggesting the presence of steady states in the absence of micelles in the reactor. The possible causes of these phenomena, and the conditions under which they occur are discussed.