scholarly journals A Framework for Long-Term Vibration-Based Monitoring of Bridges

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4739
Author(s):  
Emrah Erduran ◽  
Frida Kristin Ulla ◽  
Lone Næss
Keyword(s):  
Strain Energy ◽  
Threshold Value ◽  
Modal Strain Energy ◽  
Damage Initiation ◽  
Damage Indicator ◽  
Damage Indicators ◽  
Long Term Monitoring ◽  
The Impact ◽  
Term Monitoring

A new framework for long-term monitoring of bridges is proposed in order to negate (i) the impact of measurement uncertainties on damage detection in vibration-based structural health monitoring and (ii) the low sensitivity of damage indicators to low levels of damage. The framework is developed using three vibration-based damage indicators that have an intuitive physical correlation with damage: modal curvature, modal strain energy and modal flexibility. The article first quantifies the efficacy of these damage indicators when based on two observations, one from the undamaged state and one from the monitored state, in detecting and locating damage for different damage levels that are simulated on an 84-m long railway bridge. A long-term monitoring framework based on a new parameter defined as the frequency of the damage indicator exceeding the threshold value within a population of observations is developed. Impact of several factors including the damage location, damage indicator used in the framework, and the noise level on the success of the developed framework was investigated through numerical analysis. The new parameter, when used together with modal strain energy, was shown to provide a very clear picture of damage initiation and development over time starting from very low damage levels. Furthermore, the location of the simulated damage can be identified successfully at all damage levels and even for very high noise levels using the proposed framework.

scholarly journals Analysis of the scores of competency test

2018 ◽  
Vol 210 ◽  
pp. 04006
Author(s):  
Jana Pasáčková
Keyword(s):  
Czech Republic ◽  
Secondary Schools ◽  
The Czech Republic ◽  
Study Programme ◽  
Level Of Knowledge ◽  
Long Term Monitoring ◽  
The University ◽  
The Impact ◽  
Term Monitoring

Since decreasing level of knowledge of mathematics is the problem at universities, not only in the Czech Republic, we try to define some reasons for that between our students from different secondary schools. The paper discusses the results of the examinations in mathematics at the university in the Czech Republic. The aim is focused on the differences between the scores of students from different secondary schools. We compare the results of two tests which students have to pass during the semester. In addition, we compare the impact of introducing a new subject called “Math seminar”. This seminar should help students to complete their knowledge of topics from mathematics of secondary schools. We observe the improvement of students who passed the Math seminar. We observe the impact of passing the school-leaving exam from mathematics as well. We would like to consider this as a part of a long-term monitoring of students in this study programme and re-analyze unsuccessful students after they pass the course “Math seminar”.

scholarly journals Long-Term Monitoring of Atrazine Contamination in Soil by ELISA

2001 ◽  
Vol 84 (1) ◽  
pp. 150-155 ◽  
Author(s):  
Karl Kramer ◽  
Johann Lepschy ◽  
Bertold Hock
Keyword(s):  
Low Cost ◽  
Threshold Value ◽  
Soil Samples ◽  
Sample Throughput ◽  
Atrazine Contamination ◽  
Long Term Monitoring ◽  
Term Monitoring ◽  
Selection Of ◽  
Hplc Data

Abstract An enzyme-linked immunoassay (ELISA) was used for screening atrazine residues in soil. Samples were annually collected in Southern Germany between 1993 and 1998. An average of 419.5 samples was analyzed per year amounting to 2517 samples. The fraction of positive samples defined by atrazine concentrations >100 μg/kg soil decreased successively from 8% (corresponding to 33 samples) in 1993 to 0.6% (corresponding to 2 samples) in 1998. All positive samples and a selection of negative samples were subsequently validated by HPLC. Comparison of ELISA and HPLC data yielded correlation coefficient values of r= 0.958–0.981 (n= 18–47), except for 1995 when only a correlation of r= 0.864 (n= 18) was obtained. Four samples were overestimated and another 4 were underestimated with respect to the atrazine threshold value of 100 μg/kg soil as revealed by HPLC validation. Thus, 99.68% of 2517 analyzed samples were correctly evaluated. The precision and reproducibility of the ELISA were adequate for a prescreening tool. The low cost per sample and the high sample throughput are not yet achievable by conventional analytical methods. The described combination of ELISA and HPLC has the potential to take advantage of both methods and to restrict determination errors to a minimum.

Experimental Analysis of the Impact on the Durability of Concrete Additions

2016 ◽  
Vol 249 ◽  
pp. 73-78 ◽  
Author(s):  
Vladimír Suchánek ◽  
Kateřina Hájková
Keyword(s):  
Free Fall ◽  
Concrete Surface ◽  
Hardened Concrete ◽  
Concrete Mixer ◽  
Long Term Monitoring ◽  
The Impact ◽  
Term Monitoring ◽  
Furnace Slag

This report deals with long term monitoring of durability properties of concrete using different weight doses of various kinds of additions. Particularly limestone, silica fume as a 50% suspension and blast furnace slag were used. Even though the basic recipe is based on the designed concrete, all the fresh concrete was made with a free-fall concrete mixer in the laboratory. This report deals with long-term monitoring of cement concrete surface resistance to water and defrosting chemicals (achieved 475 cycles). The article also describes results of following tests: determination of concrete frost resistance, depth of water penetration under pressure and depth of chloride penetration. Standard tests of fresh and hardened concrete specimens complement the experiment.

scholarly journals The impact of road maintenance and construction on roadside vegetation

2021 ◽  
Vol 11 (225) ◽  
Author(s):  
Alexander Sudnik ◽  
◽  
Irina Voznyachuk
Keyword(s):  
Climatic Factors ◽  
Road Maintenance ◽  
Sources Of Pollution ◽  
Mobile Sources ◽  
Roadside Vegetation ◽  
Long Term Monitoring ◽  
The Impact ◽  
Negative Factors ◽  
Term Monitoring

The article provides data on the results of long-term monitoring of the state of vegetation along the main highways of Belarus, caused by environmental pollution in roadside strips with deicing reagents based on sodium chloride in winter in combination with a set of other negative factors (exhaust gases from mobile sources of pollution, changes in environmental conditions, extreme manifestations of weather and climatic factors).

Clams after storms: the impact of multiple disturbances on seep vesicomyid clams revealed by long-term monitoring

2019 ◽  
Vol 166 (3) ◽  
Author(s):  
Ryota Nakajima ◽  
Chong Chen ◽  
Ryoichi Iwase ◽  
Hiroyuki Yamamoto ◽  
Katsunori Fujikura
Keyword(s):  
Multiple Disturbances ◽  
Long Term Monitoring ◽  
The Impact ◽  
Term Monitoring

scholarly journals The Italian TREETALKER NETWORK (ITT-Net): continuous large scale monitoring of tree functional traits and vulnerabilities to climate change

2020 ◽  
Author(s):  
Simona Castaldi ◽  
Serena Antonucci ◽  
Shahla Asgharina ◽  
Giovanna Battipaglia ◽  
Luca Belelli Marchesini ◽  
...  
Keyword(s):  
Climate Change ◽  
Real Time ◽  
High Frequency ◽  
Large Scale ◽  
Operation Mode ◽  
Cloud Services ◽  
Long Term Monitoring ◽  
The Impact ◽  
Term Monitoring

<p>The  <strong>Italian TREETALKER NETWORK (ITT-Net) </strong>aims to respond to one of the grand societal challenges: the impact of climate changes on forests ecosystem services and forest dieback. The comprehension of the link between these phenomena requires to complement the most classical approaches with a new monitoring paradigm based on large scale, single tree, high frequency and long-term monitoring tree physiology, which, at present, is limited by the still elevated costs of multi-sensor devices, their energy demand and maintenance not always suitable for monitoring in remote areas. The ITT-Net network will be a unique and unprecedented worldwide example of real time, large scale, high frequency and long-term monitoring of tree physiological parameters. By spring 2020, as part of a national funded project (PRIN) the network will have set 37 sites from the north-east Alps to Sicily where a new low cost, multisensor technology “the TreeTalker®” equipped to measure tree radial growth, sap flow, transmitted light spectral components related to foliage dieback and physiology and plant stability (developed by Nature 4.0), will monitor over 600 individual trees. A radio LoRa protocol for data transmission and access to cloud services will allow to transmit in real time high frequency data on the WEB cloud with a unique IoT identifier to a common database where big data analysis will be performed to explore the causal dependency of climate events and environmental disturbances with tree functionality and resilience.</p><p>With this new network, we aim to create a new knowledge, introducing a massive data observation and analysis, about the frequency, intensity and dynamical patterns of climate anomalies perturbation on plant physiological response dynamics in order to: 1) characterize the space of “normal or safe tree operation mode” during average climatic conditions; 2) identify the non-linear tree responses beyond the safe operation mode, induced by extreme events, and the tipping points; 3) test the possibility to use a high frequency continuous monitoring system to identify early warning signals of tree stress which might allow to follow tree dynamics under climate change in real time at a resolution and accuracy that cannot always be provided through forest inventories or remote sensing technologies.</p><p>To have an overview of the ITT Network you can visit www.globaltreetalker.org</p><p> </p>

The impact of climate change on vadose zone pore waters and its implication for long-term monitoring

2003 ◽  
Vol 29 (3) ◽  
pp. 399-411 ◽  
Author(s):  
William E Glassley ◽  
John J Nitao ◽  
Charles W Grant ◽  
James W Johnson ◽  
Carl I Steefel ◽  
...  
Keyword(s):  
Climate Change ◽  
Vadose Zone ◽  
Pore Waters ◽  
Impact Of Climate Change ◽  
Long Term Monitoring ◽  
The Impact ◽  
Term Monitoring
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