Structural Health Monitoring (SHM) with emerging technologies like e.g. fibre optic sensors, lasers, radars, acoustic emission and Micro Electro Mechanical Systems (MEMS) made an entrance into the civil engineering field in last decades. Expansion of new technologies together with development in data communication benefited for rapid development. The author has been doing research as well as working with SHM and related tasks nearly a decade. Both theoretical knowledge and practical experience are gained in this constantly developing field. This doctoral thesis presents lessons learned in SHM and sensory technologies when monitoring civil engineering structures, mostly bridges. Nevertheless, these techniques can also be used in most applications related to civil engineering like dams, high rise buildings, off-shore platforms, pipelines, harbour structures and historical monuments. Emerging and established technologies are presented, discussed and examples are given based on the experience achieved. A special care is given to Fibre Optic Sensor (FOS) technology and its latest approach. Results from crack detection testing, long-term monitoring, and sensor comparison and installation procedure are highlighted. The important subjects around sensory technology and SHM are discussed based on the author's experience and recommendations are given. Applied research with empirical and experimental methods was carried out. A state-of-the art-review of SHM started the process but extensive literature studies were done continuously along the years in order to keep the knowledge up to date. Several SHM cases, both small and large scale, were carried out including sensor selection, installation planning, physical installation, data acquisition set-up, testing, monitoring, documentation and reporting. One case study also included modification and improvement of designed system and physical repair of sensors as well as two Site Acceptance Tests (SATs) and the novel crack detection system testing. Temporary measuring and testing also took place and numerous Structural Health Monitoring Systems (SHMSs) were designed for new bridges. The observed and measured data/phenomena were documented and analysed.  Engineers, researchers and owners of structures are given an essential implement in managing and maintaining structures. Long-term effects like shrinkage and creep in pre-stressed segmental build bridges were studied. Many studies show that existing model codes are not so good to predict these long-term effects. The results gained from the research study with New Årsta Railway Bridge are biased be the fact that our structure is indeed special. Anyhow, the results can be compared to other similar structures and adequately used for the maintenance planning for the case study. A long-term effect like fatigue in steel structures is a serious issue that may lead to structural collapse. Novel crack detection and localisation system, based on development on crack identification algorithm implemented in DiTeSt system and SMARTape delamination mechanism, was developed, tested and implemented. Additionally, new methods and procedures in installing, testing, modifying and improving the installed system were developed. There are no common procedures how to present the existing FOS techniques. It is difficult for an inexperienced person to judge and compare different systems. Experience gained when working with Fibre Optic Sensors (FOS) is collected and presented. The purpose is, firstly to give advice when judging different systems and secondly, to promote for more standardised way to present technical requirements. Furthermore, there is need to regulate the vocabulary in the field. Finally, the general accumulated experience is gathered. It is essential to understand the complexity of the subject in order to make use of it. General trends and development are compared for different applications. As the area of research is wide, some chosen, specific issues are analysed on a more detailed level. Conclusions are drawn and recommendations are given, both specific and more general. SHMS for a complex structure requires numerous parameters to be measured. Combination of several techniques will enable all required measurements to be taken. In addition, experienced specialists need to work in collaboration with structural engineers in order to provide high-quality systems that complete the technical requirement. Smaller amount of sensors with proper data analysis is better than a complicated system with numerous sensors but with poor analysis. Basic education and continuous update for people working with emerging technologies are also obligatory. A lot of capital can be saved if more straightforward communication and international collaboration are established: not only the advances but also the experienced problems and malfunctions need to be highlighted and discussed in order not to be repeated. Quality assurance issues need to be optimized in order to provide high quality SHMSs. Nevertheless, our structures are aging and we can be sure that the future for sensory technologies and SHM is promising. The final conclusion is that an expert in SHM field needs wide education, understanding, experience, practical sense, curiosity and preferably investigational mind in order to solve the problems that are faced out when working with emerging technologies in the real world applications.  The human factor, to be able to bind good relationship with workmanship cannot be neglected either. There is also need to be constantly updated as the field itself is in continuous development. / QC 20111117 / SHMS of the New Årsta Railway Bridge

In Partnerschaft mit dem VDI-Kolloquium Bodenbearbeitung erwarten Sie am Institut für Bau- und Landma­ schinentechnik/lBL interessante Workshops, Vorträge und Diskussionen zu Anforderungen, Möglichkeiten so­ wie Trends in der Bodenbearbeitung und deren Auswirkungen auf ein zukünftiges Biosphärenmonitoring. Das vom BMBF geförderte Innovationsforum SeBiMo hat das Ziel technologische Lösungsansätze für eine effektive und universelle Bodensensorik zu identifizieren, die eine exakte Zustandsbestimmung direkt im Boden bzw. in der Pflanze ermöglichen. Das interdisziplinär aufgestellte Forum bündelt dabei Kompetenzen von Sen­ sorik-Entwicklern und -Herstellern, Agrartechnikunternehmen, Dienstleistern für die Landwirtschaft sowie For­schungseinrichtungen aus Mitteldeutschland. Die Partner des Innovationsforums streben an, sensortechnische Verfahren für eine umfassende Bodenraumerkundung und für die Bestimmung wesentlicher Pflanzenparameter zu definieren, die über Einzellösungen hinausgehen und der Landwirtschaft Handlungsempfehlungen für den gesamten pflanzenbaulichen Prozess von der Bodenbearbeitung bis zur Ernte geben. Die Ergebnisse werden im Rahmen dieser Veranstaltung präsentiert und diskutiert.

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Motivation - Einsatz gezogener, passiver Werkzeuge als Universalgeräte zur Bodenbearbeitung Probleme: - Zugkraftbedarf - Verschleiß - Verfahrenssicherheit

Im Beruf, in der Freizeit und in der Rehabilitation werden immer öfter digitale Medien eingesetzt. Speziell in der motorischen Rehabilitation wird zunehmend eine Digitalisierung der Therapieprozesse festgestellt. Dieser Trend soll den Therapieprozess dokumentieren, die Patienten motivieren und auch eine Unterstützung für die Therapeuten sein. Gegenwärtig werden in der Praxis verschiedene „Feedback-Informationen“ verwendet, beispielsweise Informationen zum Bewegungsweg und zur Bewegungsgeschwindigkeit. In der Regel kommen diese Informationen primär vom Trainingsgerät, da dort die entsprechenden Sensoren angebracht sind. Die Information zur Bewegungsqualität des Patienten selbst, wird von den Sensoren nicht erfasst. Im Rahmen des Projektes „AssiSt“ (Assistierte Bewegungskontrolle in der Rehabilitation durch intelligente Sensortechnologie) wurde ein anderer Ansatz verfolgt. Hier war es das Ziel, ein Assistenzsystem zu entwickeln, welches einem Patienten während seiner Übungsausführung Feedback geben kann. Es galt dabei zu prüfen, inwiefern mit einem optischen Sensor die Bewegung des Übenden direkt erfasst und in Echtzeit auf fehlerhafte Bewegungsausführungen/oder die/eine fehlerhafte Bewegungsausführung analysiert werden kann. Eine falsche Bewegungsausführung kann dazu führen, dass die Zielmuskulatur nicht richtig angesteuert wird. Darüber hinaus können aktive und passive Strukturen in der frühen postoperativen Phase überlastet werden. Hierfür wurde mithilfe von Methoden des maschinellen Lernens die Bewegung des Übenden auf Fehlerbilder hin analysiert. Bei fehlerhafter Ausführung werden dabei über eine Feedbackeinheit sofort Korrekturhinweise übermittelt, sodass auftretende Fehler zeitnah korrigiert werden können. Im Verlauf klinischer Tests wurde das Feedback des Assistenzsystems mit der Analyse eines Therapeuten verglichen, wobei eine gute Übereinstimmung erzielt wurde. Neben der Bewegungsanalyse wird durch das System zusätzlich eine Verlaufsdokumentation erstellt, sodass Patienten und Therapeuten nachträglich den Therapieverlauf auswerten können. Darüber hinaus wurde untersucht, ob Biosignale, wie bspw. die Erwärmung der Hautoberfläche infolge der Muskelarbeit während des Trainings, als Feedback geeignet sind. Dies könnte das Effektwissen des Patienten durch ein besseres Verständnis zwischen der Therapieübung und der Muskelansteuerung verbessern.

<p>  </p> <p>Graphene is a two-dimensional (2-D) sheet of <em>sp2</em> hybridized carbon atoms with extraordinary thermal, electrical, and mechanical properties. Among numerous sophisticated and costly synthesis techniques including chemical vapor deposition (CVD), SiC and microwave plasma; liquid-phase exfoliation (LPE) has been one of the most widely used techniques for low-cost and large scale graphene synthesis since it was first reported in 2008. LPE involves the use of liquid media to exfoliate graphite precursors directly into mono- or few-layered graphene. Stable dispersions of few-layered graphene are desirable for thin-film deposition on a large scale but are limited by the use of polar organic solvents with high boiling points and unfavorable toxicity profiles. This limitation can be overcome by milling and exfoliation of graphene nanoplatelets (GrNPs) in ethyl acetate (EtOAc) and acetone, volatile solvents with low toxicity profiles and modest environmental impact. Solvent-assisted grinding of pristine GrNPs on a horizontal ball mill followed by sonication produces concentrated suspensions up to 356 µg/mL that remain stable at room temperature for a minimum of 6 weeks without the addition of surfactants. Exfoliated graphene layers have an average thickness of 4.5 nm which corresponds to 10–12 layers of graphene on Si/SiO2 substrates. EtOAc and acetone-based dispersions of exfoliated graphene can be deposited uniformly using conventional airbrush equipment as low-boiling point solvents evaporates instantaneously after deposition. This deposition method also provides freedom regarding to target substrate and overcomes any substrate related limitations observed in other techniques. Practical demonstrations of spray-coated graphene films include (i) conductive surfaces with sheet resistance as low as 1 kΩ/sq, and (ii) solid contacts for disposable and low-cost nitrate-selective electrodes, with high reproducibility in the voltage readouts across multiple sensors.</p>

Wissenschaftliche Schriftenreihe, die Dissertationen der Professur Mess- und Sensortechnik beinhaltet. / Scientific series containing dissertations of the Professorship of Measurement and Sensor Technology.

Current controls the motion of a manipulator. The manipulators at ABB are powered by a three-phase alternating current system where shunt resistors are utilised to measure the current to the motors. Magnetic field sensors are instead investigated to eliminate issues with power losses, the number of components and the cost of the shunt resistors. Since current produces a magnetic field, it can be measured without contact using a magnetic field sensor. However, employing non-contact magnetic field sensors in three-phase implementations introduces problems with stray magnetic fields due to the three traces being in close proximity to each other. This magnetic crosstalk will influence the sensors, hence the current measurement for each trace. In this thesis separating this influence of the magnetic fields is done through a software approach. Initially, two magnetic field sensors, a tunnel magnetoresistance sensor and a Fluxgate sensor, were tested and evaluated to gain knowledge and understanding. From the different tests, it was decided to continue with the Fluxgate sensor. Further, a partial least-squares regression was constructed to separate the magnetic field and predict the current in each trace from the Fluxgate sensor output. From a simulation created, the current could be predicted with an error of approximately 1 nA, meaning less than 0.1% when considering a simulated linear model of the Fluxgate sensor.

Mechanical overburdening is a major risk factor that provokes non-infectious claw diseases. Moreover, lameness-causing lesions often remain undetected and untreated. Therefore, prevention of claw tissue overburdening is of interest, especially by analyzing harmful effects within dairy cows’ housing environment. However, objective “on-cow” methods for bovine gait analysis are underdevel- oped. The purpose of the study was to apply an innovative mobile pressure sensor system attached at the claws to perform pedobarometric gait analysis. A further goal was the supplementation with accelerative data, generated simultaneously by use of two inertial measurement units (IMUs), attached at metatarsal level. IMU data were analyzed with an automatic step detection algorithm. Gait analysis was performed in ten dairy cows, walking and trotting on concrete flooring and rubber mats. In addition to the basic applicability of the sensor systems and with the aid of the automatic step detection algorithm for gait analysis in cows, we were able to determine the impact of the gait and flooring type on kinematic and kinetic parameters. For pressure sensor output, concrete was associated with significantly (p < 0.001) higher maximum and average pressure values and a significantly smaller contact area, compared to rubber mats. In contrast to walking, trotting led to a significantly higher force, especially under the medial claw. Further, IMU-derived parameters were significantly influenced by the gait. The described sensor systems are useful tools for detailed gait analysis in dairy cows. They allow the investigation of actors which may affect claw health negatively.