Analytische Chemie
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- 2019 (52) (entfernen)
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- Mobile Robot Olfaction (9)
- Nano aerial robot (7)
- Swarm (7)
- TDLAS (6)
- Apis mellifera (4)
- Gas dispersion simulation (4)
- Gas tomography (4)
- Indoor air quality (4)
- Tomographic reconstruction of gas plumes (4)
- Varroa destructor (4)
Organisationseinheit der BAM
- 8.1 Sensorik, mess- und prüftechnische Verfahren (52) (entfernen)
Eingeladener Vortrag
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Small unmanned aircraft are used increasingly as flying sensor platforms to perform tasks such as gas distribution mapping or environmental monitoring. Sometimes, these applications require knowledge of the ambient wind field.
In general, it would be interesting to avoid any additional hardware, both on ground and on the aircraft. Here, we present an approach to estimate the wind vector just by exploiting the state variables of the aircraft.
An equation for wind vector estimation using a multirotor aircraft as a flying anemometer is shown. To compute the wind vector an estimate of the thrust of the aircraft is required, which is related to the rotational speed of the rotors. Hence, a sensing system for the rotational speed using phototransistors is presented.
Feuchte, sei es Material- oder Gasfeuchte, ist eine wichtige Messgröße bei der Qualitätsbeurteilung von Kunststoffen, landwirtschaftlichen Erzeugnissen, Energieträgern, Arzneimitteln, industriell und medizinisch verwendeten Gasen. Deswegen gibt es ein Interesse Feuchtemesserfahren hinsichtlich Präzision, Wiederholbarkeit, Rückführbarkeit und Stabilität kontinuierlich zu verbessern. Ein bewährtes Messprinzip für diese Aufgabe wurde bereits 1959 von Keidel entwickelt und basiert auf der Absorption und Elektrolyse von Wasserdampf. Der einfache Aufbau dieses Prinzips besteht aus einem Sensorelement, einer Gleichspannungsquelle, einem Digitalmultimeter und einen geregelten Gasstrom über den Sensor. Nach dem Faraday’schen Gesetz der Elektrolyse korreliert bei dem Messprinzip die Ladungsmenge mit der elektrolysierten Wassermasse. Jedoch bedarf es in der heutigen Zeit einer Validierung der Sensoren, weil durch gezielte Miniaturisierung weniger aktive Fläche vorhanden ist und somit das Faraday’sche Gesetz nicht vollständig anwendbar ist. In dieser Arbeit wurden coulometrische Sensoren mit einer planaren Elektrodenstruktur hinsichtlich der Einflüsse von unterschiedlichen Gasen, der Gastemperatur und dem -druck untersucht. Zusätzlich wurde eine neuartige Sensorbeschichtung basierend auf einer ionischen Flüssigkeit getestet. Des Weiteren wurde ein Messgerät für die abgestufte Bestimmung der Materialfeuchte und Wasseraktivität entwickelt und dessen messtechnischer Einsatz untersucht.
Die BAM ist nahezu über die gesamte Wertschöpfungskette hinweg wissenschaftlich tätig. Von der sicheren und effizienten Wasserstofferzeugung (POWER-to-GAS), über die (Zwischen-)Speicherung von Wasserstoff in Druckgasspeichern bis hin zum Transport bspw. mittels Trailerfahrzeug zum Endverbraucher.
Komplettiert werden die Aktivitäten der BAM durch die sicherheitstechnische Beurteilung von wasserstoffhaltigen Gasgemischen, die Verträglichkeitsbewertung von Werkstoffen bis hin zur Detektion von Wasserstoffkonzentrationen über geeignete Sensorik, auch mittels ferngesteuerter Messdrohnen (sog. UAV-Drohnen).
Zudem untersucht die BAM proaktiv Schadensrisiken und Unfallszenarien für die Sicherheitsbetrachtung, um mögliche Schwachstellen aufzeigen und potenzielle Gefährdungen erkennen zu können.
Against the background of sustainable resource management and efficiency, wood-based materials are currently experiencing a revival and, among others, plywood, Laminated Veneer Lumber and glued laminated timber are becoming increasingly more important in the building sector. Even though these materials are so-called engineered products, the element wood is naturally grown with intrinsic variability in mechanical properties and requires professional handling on-site. Otherwise, load-bearing structures made of wood materials may entail certain risks. Critical situations can, in principle, be avoided by implementing a structural health monitoring system into components or structures made from wood material. The aim is to indicate accumulation of mechanical damage and to eliminate or at least significantly reduce the risk of unexpected failure. Toward this purpose, the failure behavior of several layered wood materials under quasi-static tension was investigated in laboratory-scale experiments by means of acoustic emission (AE) measurement. Based on spectral analysis and pattern recognition, two classes of AE signals are identified for each investigated lay-up that are characterized by either low or high frequency contents in the respective power spectra. AE activity and intensity of both signal classes are analyzed, striving for predictors appropriate for AE monitoring concepts.
Against the background of sustainable resource management and efficiency, wood-based materials are currently experiencing a revival and, among others, plywood, Laminated Veneer Lumber and glued laminated timber are becoming increasingly more important in the building sector. Even though these materials are so-called engineered products, the element wood is naturally grown with intrinsic variability in mechanical properties and requires professional handling on-site. Otherwise, load-bearing structures made of wood materials may entail certain risks. Critical situations can, in principle, be avoided by implementing a structural health monitoring system into components or structures made from wood material. The aim is to indicate accumulation of mechanical damage and to eliminate or at least significantly reduce the risk of unexpected failure. Toward this purpose, the failure behavior of several layered wood materials under quasi-static tension was investigated in laboratory-scale experiments by means of acoustic emission (AE) measurement. Based on spectral analysis and pattern recognition, two classes of AE signals are identified for each investigated lay-up that are characterized by either low or high frequency contents in the respective power spectra. AE activity and intensity of both signal classes are analyzed, striving for predictors appropriate for AE monitoring concepts.
This work presents the testing of a developed elec¬tronic nose for outdoor odour nuisance monitoring. The sensor system consists of a sampling system, a measuring cell equipped with commercially available low-cost gas sensor elements and a data acquisition system. The sensor testing showed that the developed prototype is able to distinguish, identify and partially quantify individual odorous substances like ethanol, ammonia and hydrogen sulphide. Ethanol and ammonia could even be detected below or near their odour threshold.
This work presents the testing of a developed electronic nose for outdoor odour nuisance monitoring. The sensor system consists of a sampling system, a measuring cell equipped with commercially available low-cost gas sensor elements and a data acquisition system. The sensor testing showed that the developed prototype is able to distinguish, identify and partially quantify individual odorous substances like ethanol, ammonia and hydrogen sulphide. Ethanol and ammonia could even be detected below or near their odour threshold.
In civil engineering, many structures are made of reinforced concrete. Most Degradation processes relevant to this material, e.g., corrosion, are related to an increased level of material moisture.
Therefore, moisture monitoring in reinforced concrete is regarded as a crucial method for structural health monitoring. In this study, passive radio frequency identification (RFID)-based sensors are embedded into the concrete. They are well suited for long-term operation over decades and are well protected against harsh environmental conditions. The energy supply and the data transfer of the humidity sensors are provided by RFID. The sensor casing materials are optimised to withstand the high alkaline environment in concrete, having pH values of more than 12. Membrane materials are also investigated to identify materials capable of enabling water vapour transport from the porous cement matrix to the embedded humidity sensor. By measuring the corresponding relative humidity with embedded passive RFID-based sensors, the cement hydration is monitored for 170 days.
Moreover, long-term moisture monitoring is performed for more than 1000 days. The Experiments show that embedded passive RFID-based sensors are highly suitable for long-term structural health monitoring in civil engineering.
Increasing traffic volume on the one hand and ageing infrastructure on the other hand have created many new challenges for maintenance and structural health monitoring of roads and bridges. In the past, many bridges and road structures have been neglected, often resulting in traffic congestion, road closure, and increased repair costs.
This research is concerned with the development of a system to improve the challenge of maintenance and early detection of damage, particularly moisture penetration and corrosion of steel reinforced concrete components. The objective is to develop a method that will also work after 30 years and longer. Many new IoT solutions are equipped with internal energy storage elements (accumulators or batteries) which are inappropriate here, since most relevant signs of concrete degradation occur after decades, where the functioning of such elements are more than questionable. The presented technology approach uses radio-frequency identification (RFID) and enables connectivity to sensors. It offers the advantage of an passive, completely independent energy supply without any energy storage components.
Since the system should be permanently embedded in concrete, it is crucial to develop a long-term stable device which is adapted to the environmental influences of the structure, e.g., long-term resistance in very alkaline environment of pH 13. In numerous experiments, the robustness of the system was tested and evaluated. Various tests with encapsulations to protect the electronics were performed, and for long-term validation different concrete specimens were instrumented with RFID-sensor-systems. Their operating time is now around two years and investigations for signs of fatigue and damage to the encapsulation and the electronics are ongoing.