60 Technik
Filtern
Erscheinungsjahr
Dokumenttyp
Volltext vorhanden
- ja (41)
Gehört zur Bibliographie
- nein (41)
Schlagworte
- Rapid Prototyping <Fertigung> (4)
- CO2-Bilanz (3)
- Elektrofahrzeug (3)
- Elektromobilität (3)
- additive manufacturing (3)
- 3D-Druck (2)
- Agglomerat (2)
- BEV (2)
- Biokatalyse (2)
- Biotechnik (2)
Institut
- FB Umweltplanung/-technik (UCB) (15)
- FB Technik (12)
- FB Bauen + Leben (6)
- IMiP - Institut für Mikroverfahrenstechnik und Partikeltechnologie (3)
- IBioPD - Institut für biotechnisches Prozessdesign (2)
- LaROS - Labor für Radiotechnologie und optische Systeme (2)
- FB Umweltwirtschaft/-recht (UCB) (1)
- Sonstiges (1)
Die Umbenetzungsagglomeration bietet die Möglichkeit einer Trennung nach zwei Partikeleigenschaften. Hierbei wird nach den Benetzungseigenschaften des Feststoffs in Bezug zur Suspensions- und Bindeflüssigkeit getrennt und nach der Größe. Ziel dieser Arbeit ist, die Reinheit der entstehenden Graphitagglomerate in einer Mischung mit Quarzsand gravimetrisch zu bestimmen und diese mit den Benetzungseigenschaften zu korrelieren. Die Güte dieser Ergebnisse wird mit einer Mikroröntgentomographie (µ-CT) untersucht. Es konnte gezeigt werden, dass sich Quarzsand mit Paraffinöl nicht benetzen lässt und somit Reinheiten von 99,5 % bis 99,9 % erreicht werden, was das Ergebnis der µ-CT bestätigt. Einen Einfluss der Partikelgröße des Quarzsandes konnte im untersuchten Bereich nicht bestätigt werden.
This research conducted a probabilistic life-cycle assessment (pLCA) into the greenhouse gas (GHG) emissions performance of nine combinations of truck size and powertrain technology for a recent past and a future (largely decarbonised) situation in Australia. This study finds that the relative and absolute life-cycle GHG emissions performance strongly depends on the vehicle class, powertrain and year of assessment. Life-cycle emission factor distributions vary substantially in their magnitude, range and shape. Diesel trucks had lower life-cycle GHG emissions in 2019 than electric trucks (battery, hydrogen fuel cell), mainly due to the high carbon-emission intensity of the Australian electricity grid (mainly coal) and hydrogen production (mainly through steam–methane reforming). The picture is, however, very different for a more decarbonised situation, where battery electric trucks, in particular, provide deep reductions (about 75–85%) in life-cycle GHG emissions. Fuel-cell electric (hydrogen) trucks also provide substantial reductions (about 50–70%), but not as deep as those for battery electric trucks. Moreover, hydrogen trucks exhibit the largest uncertainty in emissions performance, which reflects the uncertainty and general lack of information for this technology. They therefore carry an elevated risk of not achieving the expected emission reductions. Battery electric trucks show the smallest (absolute) uncertainty, which suggests that these trucks are expected to deliver the deepest and most robust emission reductions. Operational emissions (on-road driving and vehicle maintenance combined) dominate life-cycle emissions for all vehicle classes. Vehicle manufacturing and upstream emissions make a relatively small contribution to life-cycle emissions from diesel trucks (<5% each), but these are important aspects for electric trucks (5% to 30%).
The research program “Engineered Artificial Minerals (EnAM)” addresses the challenge of recycling valuable elements from battery waste streams. These elements, such as lithium (Li), often migrate in the slag phase, in some cases as crystals. EnAM crystals represent concentrated reservoirs of these elements, which can only be effectively recycled if they are extracted from the slag matrix and then separated. Selective wet agglomeration is a separation process based on a three-phase system and is often used in coal and ore processing. The produced agglomerates in this process can be easily separated from the remaining suspension. The precise quantification of the wetting properties and adhesion strength between suspended particles and binding liquid droplets is a scientific challenge. An accurate technique suitable for adhesion force measurements in three-phase systems with micrometer-scale particles is Fluidic Force Microscopy (FluidFM®). An experimental setup with optical control is being developed to measure adhesion forces between droplets and flat/rough surfaces. This will enable precise measurements of adhesion forces between solid EnAM crystals and binding liquid droplets. Based on these measurements, optimal agglomeration conditions can be selected in the future to improve selective wet agglomeration with respect to recycling processes.
The aim of this work was to develop a novel method for studying the 3D morphology of agglomerates obtained by spherical agglomeration. It has been found, that the combination of shock-freezing the samples in a mixture of ethanol and dry ice followed by an X-ray microtomography measurement leads to useful results. Hereby, the image quality for low absorbing material like the used graphite was enhanced by propagation-based X-ray microtomography, which results in phase contrast images. We also discuss our 3D image post-processing routine, which is used to determine the morphology parameters sphericity, fractal dimension and packing density. Furthermore, a two-dimensional kernel density estimation is used to calculate the joint probability density of agglomerate size and the morphology parameter. In future, this method will be used to determine the morphological behaviour of agglomerates during the different phases of spherical agglomeration.
More and more universities are recognizing their role model and creative function in society and are acting accordingly - also in terms of mobility. In this way, universities can make an important contribution to climate protection, as mobility is responsible for more than 20 percent of global greenhouse gas emissions. The GreenMetric ranking also takes the area of mobility into account via the Transportation category, which is weighted at 18%. This paper uses the example of the Environmental Campus Birkenfeld at Trier University of Applied Sciences, Germany, to show what opportunities universities in rural areas have to reduce transportation-related emissions of students and employees. The possibilities of avoiding transportation as well as different solutions for the reduction of transportation-related greenhouse gas emissions are discussed. Furthermore, conflicts of objectives inherent to the university system in the area of mobility are considered, especially in the area of internationalization.
Additive manufacturing is an essential tool in innovative production processes. The extended degrees of freedom offer much potential in usage, construction, and product design. Rising raw material and energy costs, constantly increasing environmental requirements, and the increasing demand for resource-saving products represent a paradigm shift in classic production processes.
In addition to the purely energetic evaluation, developing energy models is a method to determine energy consumption and reduce it in the long term. The specific energy consumption model, also known as the SEC model, allows a quick estimation of energy consumption by multiplying the SEC with a unit like the mass of the workpiece, the manufacturing time, or the exposed area. Here, high dependence on the used machine, the considered peripheral devices, and the geometry are noticeable.
Previous studies, such as those by Kellens et al. and Baumers et al., have laid the basis for understanding the energy demands of PBF-LB/M processes. Various energy models have subsequently been proposed, including those by Paul and Anand, Yi et al., Lv et al., and Hui et al. These models are often limited by their specificity to sub-processes or subsystems. This results in limitations in their applicability to other manufacturing machines or inaccuracies in energy consumption predictions. The simulation accuracy ACC is mostly in the range of 90% with the limitation of small sample sizes. Moreover, nearly, all these models rely heavily on process time information, making the accuracy of their simulations largely dependent on the quality of the underlying time model.
In the following study, two manufacturing machines of the PBF-LB/M process are analyzed and compared with other studies. The aim is to analyze the power and resource consumption to use these data to build an improved energy model with a high accuracy, which can be used as an additional parameter in the adapted design methodology. Furthermore, potential savings are derived from the load curves.
Background: The environmental impact of electric scooters has been the subject of critical debate in the scientific community for the past 5 years. The data published so far are very inhomogeneous and partly methodologically incomplete. Most of the data available in the literature suffer from an average bias of 34%, because end-of-life (EOL) impacts have not been modelled, reported or specified. In addition, the average lifetime mileage of shared fleets of e-scooters, as they are operated in cities around the world, has recently turned out to be much lower than expected. This casts the scooters in an unfavourable light for the necessary mobility transition. Data on impact categories other than the global warming potential (GWP) are scarce. This paper aims to quantify the strengths and weaknesses of e-scooters in terms of their contribution to sustainable transport by more specifically defining and extending the life cycle assessment (LCA) modelling conditions: the modelling is based on two genuine material inventories obtained by dismantling two different e-scooters, one based on a traditional aluminium frame and another, for the first time, based on plastic material.
Results: This study provides complete inventory data to facilitate further LCA modelling of electric kick scooters. The plastic scooter had a 26% lower lifetime GWP than the aluminium vehicle. A favourable choice of electric motor promises a further reduction in GWP. In addition to GWP, the scooter's life cycles were assessed across seven other impact categories and showed no critical environmental or health impacts compared to a passenger car. On the other hand, only the resource extraction impact revealed clear advantages for electric scooters compared to passenger cars.
Conclusions: Under certain conditions, scooters can still be an important element of the desired mobility transition. To assure a lifetime long enough is the crucial factor to make the electric scooter a favourable or even competitive vehicle in a future sustainable mobility system. A scooter mileage of more than 5400 km is required to achieve lower CO2eq/pkm emissions compared to passenger cars, which seems unlikely in today's standard use case of shared scooter fleets. In contrast, a widespread use of e-scooters as a commuting tool is modelled to be able to save 4% of greenhouse gas (GHG) emissions across the German mobility sector.
Dielectric properties of unidirectional and biaxial flax/epoxy composites at frequencies up to 1 GHz
(2023)
The relative permittivity of flax/epoxy composites in unidirectional and biaxial orientations was mapped in the frequency range of 1 kHz to 200 kHz, and for the first time in the range of 1 MHz to 1 GHz. In addition, permittivity was investigated for the first time in the temperature range between − 20 °C and 50 °C. These composites, produced using the vacuum infusion process, are increasingly used for sustainable and lightweight structural components in the automotive industry. The relative permittivity was determined using a self-developed plate capacitor with an LCR bridge and an impedance analyzer. An examination of the microstructure of the flax/epoxy composites shows that the fibers are disordered in the composite, resulting in local variations in fiber volume fraction. Furthermore, it was shown that the matrix also infiltrates into the fiber itself, resulting in an increase of the matrix fraction. It was found that unidirectional fabrics had a higher relative permittivity than biaxial fabrics, due to a higher fiber volume fraction and lower proportion of epoxy. The results suggest that it is the fiber volume fraction, rather than the manufacturing process and fiber orientation, that primarily determines the relative permittivity. It was also found that the permittivity continues to decrease below room temperature and thus behaves in a manner typical of the material in this temperature range as well.
Deep brain stimulation (DBS) is an established therapy for movement disorders such as in Parkinson's disease (PD) and essential tremor (ET). Adjusting the stimulation parameters, however, is a labour-intensive process and often requires several patient visits. Physicians prefer objective tools to improve (or maintain) the performance in DBS. Wearable motion sensors (WMS) are able to detect some manifestations of pathological signs, such as tremor in PD. However, the interpretation of sensor data is often highly technical and methods to visualise tremor data of patients undergoing DBS in a clinical setting are lacking. This work aims to visualise the dynamics of tremor responses to DBS parameter changes with WMS while patients performing clinical hand movements. To this end, we attended DBS programming sessions of two patients with the aim to visualise certain aspects of the clinical examination. PD tremor and ET were effectively quantified by acceleration amplitude and frequency. Tremor dynamics were analysed and visualised based on setpoints, movement transitions and stability aspects. These methods have not yet been employed and examples demonstrate how tremor dynamics can be visualised with simple analysis techniques. We therefore provide a base for future research work on visualisation tools in order to assist clinicians who frequently encounter patients for DBS therapy. This could lead to benefits in terms of enhanced evaluation of treatment efficacy in the future.
For the assessment of human reaction time, a test environment was developed. This system consists of an embedded device with organic light-emitting diode (OLED) displays with push buttons for the combined presentation of visual stimulation and registration of the haptic human reaction. The test leader can define the test sequence with the aid of a graphical user interface (GUI) on a personal computer (PC). The validation of the system was proved by measuring the latency times of the whole system, which are conditioned by the specific hard- and software constellation. Through the investigation of the display’s light radiation by a photodiode and the recorded current consumption, latency times and their variance were specified. In the fastest mode the system can reach an error limit of 60 μs.
