<?xml version="1.0" encoding="utf-8"?>
<export-example>
  <doc>
    <id>54231</id>
    <completedYear/>
    <publishedYear>2022</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>738</pageFirst>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue>3</issue>
    <volume>15</volume>
    <type>article</type>
    <publisherName>MDPI</publisherName>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>1</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Correlation of Load-Bearing Behavior of Reinforced Concrete Members and Velocity Changes of Coda Waves</title>
    <abstract language="eng">The integral collection of information such as strains, cracks, or temperatures by ultrasound offers the best prerequisites to monitor structures during their lifetime. In this paper, a novel approach is proposed which uses the collected information in the coda of ultrasonic signals to infer the condition of a structure. This approach is derived from component tests on a reinforced concrete beam subjected to four-point bending in the lab at Ruhr University Bochum. In addition to ultrasonic measurements, strain of the reinforcement is measured with fiber optic sensors. Approached by the methods of moment-curvature relations, the steel strains serve as a reference for velocity changes of the coda waves. In particular, a correlation between the relative velocity change and the average steel strain in the reinforcement is derived that covers 90% of the total bearing capacity. The purely empirical model yields a linear function with a high level of accuracy (R 2 =0.99, R2=0.99,  RMSE≈90μ &#13;
RMSE≈90μ strain).</abstract>
    <parentTitle language="eng">Materials</parentTitle>
    <identifier type="doi">10.3390/ma15030738</identifier>
    <identifier type="urn">urn:nbn:de:kobv:b43-542316</identifier>
    <enrichment key="opus.source">publish</enrichment>
    <enrichment key="date_peer_review">21.02.2022</enrichment>
    <licence>Creative Commons - CC BY - Namensnennung 4.0 International</licence>
    <author>F. Clauß</author>
    <author>Niklas Epple</author>
    <author>M. A. Ahrens</author>
    <author>Ernst Niederleithinger</author>
    <author>P. Mark</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Ultrasound</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Coda Wave Interferometry (CWI)</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Structural Health Monitoring</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Reinforced Concrete</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Embedded Sensors</value>
    </subject>
    <collection role="ddc" number="543">Analytische Chemie</collection>
    <collection role="ddc" number="624">Ingenieurbau</collection>
    <collection role="institutes" number="">8 Zerstörungsfreie Prüfung</collection>
    <collection role="institutes" number="">8.2 Zerstörungsfreie Prüfmethoden für das Bauwesen</collection>
    <collection role="themenfelder" number="">Infrastruktur</collection>
    <collection role="themenfelder" number="">Chemie und Prozesstechnik</collection>
    <collection role="literaturgattung" number="">Verlagsliteratur</collection>
    <collection role="fulltextaccess" number="">Datei für die Öffentlichkeit verfügbar ("Open Access")</collection>
    <collection role="unnumberedseries" number="">Wissenschaftliche Artikel der BAM</collection>
    <thesisPublisher>Bundesanstalt für Materialforschung und -prüfung (BAM)</thesisPublisher>
    <file>https://opus4.kobv.de/opus4-bam/files/54231/materials-15-00738.pdf</file>
  </doc>
  <doc>
    <id>55687</id>
    <completedYear/>
    <publishedYear>2022</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>1</pageFirst>
    <pageLast>15</pageLast>
    <pageNumber/>
    <edition/>
    <issue>16</issue>
    <volume>15</volume>
    <type>article</type>
    <publisherName>MDPI</publisherName>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>1</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Impact of External Mechanical Loads on Coda Waves in Concrete</title>
    <abstract language="eng">During their life span, concrete structures interact with many kinds of external mechanical loads. Most of these loads are considered in advance and result in reversible deformations. Nevertheless, some of the loads cause irreversible, sometimes unnoticed changes below the macroscopic scale depending on the type and dimension of the impact. As the functionality of concrete structures is often relevant to safety and society, their condition must be known and, therefore, assessed on a regular basis. Out of the spectrum of non-destructive monitoring methods, Coda Wave Interferometry using embedded ultrasonic sensors is one particularly sensitive technique to evaluate changes to heterogeneous media. However, there are various influences on Coda waves in concrete, and the interpretation of their superimposed effect is ambiguous. In this study, we quantify the relations of uniaxial compression and uniaxial tension on Coda waves propagating in normal concrete. We found that both the signal correlation of ultrasonic signals as well as their velocity variation directly reflect the stress change in concrete structures in a laboratory environment. For the linear elastic range up to 30% of the strength, we calculated a velocity variation of −0.97‰/MPa for compression and 0.33%/MPa for tension using linear regression. In addition, these parameters revealed even weak irreversible changes after removal of the load. Furthermore, we show the time-dependent effects of shrinkage and creep on Coda waves by providing the development of the signal parameters over time during half a year together with creep recovery. Our observations showed that time-dependent material changes must be taken into account for any comparison of ultrasonic signals that are far apart in time. The study’s results demonstrate how Coda Wave Interferometry is capable of monitoring stress changes and detecting even small-size microstructural changes. By indicating the stated relations and their separation from further impacts, e.g., temperature and moisture, we anticipate our study to contribute to the qualification of Coda Wave Interferometry for its application as an early-warning system for concrete structures.</abstract>
    <parentTitle language="eng">Materials</parentTitle>
    <identifier type="doi">10.3390/ma15165482</identifier>
    <identifier type="issn">1996-1944</identifier>
    <identifier type="urn">urn:nbn:de:kobv:b43-556878</identifier>
    <enrichment key="opus.source">publish</enrichment>
    <enrichment key="date_peer_review">14.09.2022</enrichment>
    <enrichment key="opus.doi.autoCreate">false</enrichment>
    <enrichment key="opus.urn.autoCreate">true</enrichment>
    <licence>Creative Commons - CC BY - Namensnennung 4.0 International</licence>
    <author>F. Diewald</author>
    <author>Niklas Epple</author>
    <author>T. Kraenkel</author>
    <author>C. Gehlen</author>
    <author>Ernst Niederleithinger</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Ultrasound</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Coda Wave Interferometry (CWI)</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Mechanical Load</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Microstructure</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Concrete</value>
    </subject>
    <collection role="ddc" number="543">Analytische Chemie</collection>
    <collection role="ddc" number="620">Ingenieurwissenschaften und zugeordnete Tätigkeiten</collection>
    <collection role="ddc" number="624">Ingenieurbau</collection>
    <collection role="institutes" number="">8 Zerstörungsfreie Prüfung</collection>
    <collection role="institutes" number="">8.2 Zerstörungsfreie Prüfmethoden für das Bauwesen</collection>
    <collection role="themenfelder" number="">Infrastruktur</collection>
    <collection role="themenfelder" number="">Material</collection>
    <collection role="themenfelder" number="">Degradationsmechanismen</collection>
    <collection role="themenfelder" number="">Chemie und Prozesstechnik</collection>
    <collection role="literaturgattung" number="">Verlagsliteratur</collection>
    <collection role="fulltextaccess" number="">Datei für die Öffentlichkeit verfügbar ("Open Access")</collection>
    <collection role="unnumberedseries" number="">Wissenschaftliche Artikel der BAM</collection>
    <thesisPublisher>Bundesanstalt für Materialforschung und -prüfung (BAM)</thesisPublisher>
    <file>https://opus4.kobv.de/opus4-bam/files/55687/materials-Diewald_Epple.pdf</file>
  </doc>
  <doc>
    <id>52012</id>
    <completedYear/>
    <publishedYear>2021</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>266</pageFirst>
    <pageLast>275</pageLast>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume>127</volume>
    <type>bookpart</type>
    <publisherName>Springer Nature</publisherName>
    <publisherPlace>Cham, Switzerland</publisherPlace>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Towards Monitoring of Concrete Structures with Embedded Ultrasound Sensors and Coda Waves – First Results of DFG for CoDA</title>
    <abstract language="eng">Due to the importance of reinforced concrete structures for modern society, damage assessment during the entire life-cycle of such structures has become a special interest in non-destructive testing. Using embedded ultrasound sensors in combination with other measurement methods, numerical modeling and self-made data collectors, tailored specifically for monitoring tasks, the German research group DFG FOR CoDA aims to investigate and develop novel methods for damage detection and rapid model updating in reinforced concrete structures. In the first stage of the project, besides the development of custom-built, low-cost data collectors, ultrasonic transducers are embedded in a large, reinforced concrete specimen on a BAM test site near Berlin. In this experiment, the influence of changing environmental conditions (mainly temperature) on the ultrasound signal is investigated using coda-wave interferometry. The results show a correlation between changes in temperature and ultrasonic velocity. Such changes must be taken into consideration in a long-term monitoring setup to distinguish between reversible and permanent changes. By correcting the data using a linear relation between concrete temperature and velocity change to remove the seasonal trends and by low-pass filtering the data to remove daily variations can remove most of the temperature influence on the ultrasound measurements.</abstract>
    <parentTitle language="eng">Lecture Notes in Civil Engineering. European Workshop on Structural Health Monitoring. Special Collection of 2020 Papers - Volume 1</parentTitle>
    <identifier type="isbn">978-3-030-64593-9</identifier>
    <identifier type="isbn">978-3-030-64594-6</identifier>
    <identifier type="doi">10.1007/978-3-030-64594-6_27</identifier>
    <enrichment key="opus.doi.autoCreate">false</enrichment>
    <enrichment key="opus.urn.autoCreate">true</enrichment>
    <author>Niklas Epple</author>
    <author>Daniel Fontoura Barroso</author>
    <author>Ernst Niederleithinger</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Ultrasound</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Coda Wave Interferometry (CWI)</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Embedded sensors</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Structural health monitoring</value>
    </subject>
    <collection role="ddc" number="624">Ingenieurbau</collection>
    <collection role="institutes" number="">8 Zerstörungsfreie Prüfung</collection>
    <collection role="institutes" number="">8.2 Zerstörungsfreie Prüfmethoden für das Bauwesen</collection>
    <collection role="themenfelder" number="">Infrastruktur</collection>
    <collection role="literaturgattung" number="">Verlagsliteratur</collection>
    <collection role="fulltextaccess" number="">Datei im Netzwerk der BAM verfügbar ("Closed Access")</collection>
  </doc>
  <doc>
    <id>54007</id>
    <completedYear/>
    <publishedYear>2021</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>1</pageFirst>
    <pageLast>7</pageLast>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>conferenceobject</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Accounting for Long Term Environmental Influences on Ultrasonic Monitoring Measurements of Reinforced Concrete Constructions with Embedded Transducers</title>
    <abstract language="eng">Ultrasound measurements in concrete are a well-known technique in civil engineering and non-destructive testing.&#13;
For consistent monitoring of a concrete structure, the common techniques, using external sensors can often not provide the appropriate degree of repeatability, as the surface of structures changes, and comparable coupling conditions cannot be guaranteed when a measurement is repeated after some time. By embedding ultrasound transducers in concrete, we aim to develop a strategy for long-term monitoring of infrastructure, especially bridges, as a supplement and extension to other techniques. Applying the so-called coda wave interferometry to these measurements we can detect subtle changes in the medium far beyond the Resolution limit of traditional time of flight methods. A smart sensor layout enables cost-efficient sensing of the entire area of interest.&#13;
Embedding the transducers might remove uncertainties like coupling or positioning changes, while other challenges remain.&#13;
Temperature and moisture content influence the structure and the transducers. These drifts need to be recorded and removed and good coupling must be ensured while not being able to visually inspect the sensor. In a multidisciplinary research group funded by the German Research Foundation, we aim to solve these problems on the way towards an ultrasound monitoring system for reinforced concrete structures. In various experiments in the lab and field, we determine the influence of temperature variations on the measurements and the equipment. As the monitoring task is the detection of irreversible damages - not reversible changes - a smart system requires a smart way of discrimination between permanent damages and reversible changes. With the data collected in these experiments, we present an approach to an environmental correction to ultrasound data to avoid a&#13;
misinterpretation of these environmental changes as damage indicators.</abstract>
    <parentTitle language="eng">Proceedings of the 10th International Conference on Structural Health Monitoring of Intelligent Infrastructure, SHMII 10</parentTitle>
    <enrichment key="eventName">10th International Conference on Structural Health Monitoring of Intelligent Infrastructure</enrichment>
    <enrichment key="eventPlace">Porto, Portugal</enrichment>
    <enrichment key="eventStart">30.06.2021</enrichment>
    <enrichment key="eventEnd">02.07.2021</enrichment>
    <enrichment key="opus.source">publish</enrichment>
    <enrichment key="opus.doi.autoCreate">false</enrichment>
    <enrichment key="opus.urn.autoCreate">true</enrichment>
    <author>Niklas Epple</author>
    <author>Daniel Fontoura Barroso</author>
    <author>Julia Hau</author>
    <author>Ernst Niederleithinger</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Ultrasound</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Coda Wave Interferometry (CWI)</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Structural Health Monitoring</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Embedded Sensors</value>
    </subject>
    <collection role="ddc" number="624">Ingenieurbau</collection>
    <collection role="institutes" number="">8 Zerstörungsfreie Prüfung</collection>
    <collection role="institutes" number="">8.2 Zerstörungsfreie Prüfmethoden für das Bauwesen</collection>
    <collection role="themenfelder" number="">Infrastruktur</collection>
    <collection role="fulltextaccess" number="">Datei im Netzwerk der BAM verfügbar ("Closed Access")</collection>
    <collection role="literaturgattung" number="">Graue Literatur</collection>
  </doc>
  <doc>
    <id>65461</id>
    <completedYear/>
    <publishedYear>2025</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>1</pageFirst>
    <pageLast>10</pageLast>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>conferenceobject</type>
    <publisherName>e-Journal of Nondestructive Testing (eJNDT)</publisherName>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Structural Monitoring in an Urban Underground Metro Station Using Cod</title>
    <abstract language="eng">Active ultrasonic monitoring with coda wave interferometry has demonstrated its potential for structural Health monitoring in concrete structures. This study investigates its application using ultrasonic transducers embedded in the ceiling of a subway station in Munich, Germany. We evaluate the impact of environmental conditions, specifically electromagnetic interference and temperature, on data quality, as well as the influence of regular loading from passing trams. Results indicate that electromagnetic interference significantly affects measurements, while temperature effects remain minimal due to the station’s stable thermal environment. Long-term measurements and a controlled load test show that both dynamic and static loading from trams induce ultrasonic velocity changes of only 0.01%–0.06%. Although the experiment demonstrates the capacity to detect structural responses and supports the feasibility of long-term monitoring, improved electromagnetic shielding and Hardware reliability are required for successful future applications.</abstract>
    <parentTitle language="eng">NDTCE 2025 - Conference Proceedings</parentTitle>
    <identifier type="issn">1435-4934</identifier>
    <identifier type="doi">10.58286/31706</identifier>
    <identifier type="urn">urn:nbn:de:kobv:b43-654619</identifier>
    <enrichment key="eventName">NDT-CE 2025</enrichment>
    <enrichment key="eventPlace">Izmir, Turkey</enrichment>
    <enrichment key="eventStart">24.09.2025</enrichment>
    <enrichment key="eventEnd">26.09.2025</enrichment>
    <enrichment key="opus.source">publish</enrichment>
    <enrichment key="opus.doi.autoCreate">false</enrichment>
    <enrichment key="opus.urn.autoCreate">true</enrichment>
    <licence>Creative Commons - CC BY - Namensnennung 4.0 International</licence>
    <author>Niklas Epple</author>
    <author>Camila Andrea Sanchez Trujillo</author>
    <author>Julia Hau</author>
    <author>Ernst Niederleithinger</author>
    <author>F. Malm</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Coda Wave Interferometry (CWI)</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Structural health monitoring (SHM)</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Concrete</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Ultrasonic testing</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Urban infrastructure</value>
    </subject>
    <collection role="ddc" number="624">Ingenieurbau</collection>
    <collection role="institutes" number="">8 Zerstörungsfreie Prüfung</collection>
    <collection role="institutes" number="">8.2 Zerstörungsfreie Prüfmethoden für das Bauwesen</collection>
    <collection role="themenfelder" number="">Infrastruktur</collection>
    <collection role="literaturgattung" number="">Verlagsliteratur</collection>
    <collection role="fulltextaccess" number="">Datei für die Öffentlichkeit verfügbar ("Open Access")</collection>
    <collection role="unnumberedseries" number="">Wissenschaftliche Artikel der BAM</collection>
    <collection role="themenfelder" number="">Verkehrsinfrastrukturen</collection>
    <thesisPublisher>Bundesanstalt für Materialforschung und -prüfung (BAM)</thesisPublisher>
    <file>https://opus4.kobv.de/opus4-bam/files/65461/NDT_CE_Epple_et_al.pdf</file>
  </doc>
</export-example>
