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Low-Emission Transport: Erfolgreiche PhD-Abschlüsse von Xue Zhang und Anish Raj Kathribail

28.07.2022
 

Xue Zhang und Anish Raj Kathribail, die beide als PhD-Studierende am Center for Low-Emission Transport tätig waren, haben vor kurzem erfolgreich Ihre Doktorratsstudien abgeschlossen. Wir gratulieren dazu sehr herzlich!
 

Zhang hatte ihre Abschlussprüfung an der KU Leuven, Kathribail schloss sein Studium an der VUB - Vrije Universiteit Brussel mit Auszeichnung ab.

Xue Zhangs Dissertation stand unter dem Titel “Development of pass-by noise prediction models for road vehicles employing machine learning”, hier der Abstract:

This work applies machine learning techniques to real-world data for developing pass-by noise models capable of accurate short-term predictions. Several aspects surrounding vehicle noise and traffic noise modelling are investigated, including single vehicle pass-by noise prediction, traffic noise sound pressure level (SPL) prediction and traffic noise annoyance prediction. The proposed approach combines object detection of video data with the development of traffic noise prediction models. The use of summary statistics is proposed to accurately represent traffic dynamic features based on individual vehicle trajectories extracted from raw video data. The traffic dynamic features are further defined as input variables of the machine-learning model, which can be continuously and flexibly adjusted if new input variables are demanded. Considering the temporal dependencies of the data samples, recurrent neural networks (RNN) are proposed for traffic noise modelling. A robust bi-directional RNN model is developed for accurately predicting continuous traffic noise SPL levels in short-term, using only traffic dynamic features as model input. Psycho-acoustic annoyance, which refers to the individual subjective perception, is defined as another output variable of the developed road traffic noise models. By taking into account annoyance as the additional output variable, the impact of excessive traffic noise can be better assessed. The developed traffic noise SPL model and annoyance model are further interpreted by applying the method of explainable Artificial Intelligence, evaluating the influence of traffic dynamics on traffic noise SPL level and annoyance level from both local and global perspectives. The model interpretations significantly increase the transparency of the black-box machine-learning models, which can serve as an effective tool to support policy makers and urban planners in their decision-making process concerning traffic noise abatement measures. In short, the proposed system has the potential to support a continuous spatial monitoring of traffic noise and warning for excessive noise with real-time follow-up intervention measures, which can eventually contribute to smart mobility management under the framework of Smart City.

Gefördert wurde die Arbeit von der EU-Kommission im Rahmen des H2020 MSCA ETN Projekts PBNv2 (Next generation Pass-By Noise approaches for new powertrain vehicles, GA 721615). We gratefully acknowledge the European Commission for its support of the Marie Sklodowska Curie program through the H2020 ETN PBNv2 project (GA 721615). nagement under the framework of Smart City.

Anish Raj Kathribails Dissertation behandelt das Thema “Surface modification of Ni-rich cathode and its study from material to laboratory prototype for high energy Li-ion batteries”. Der Abstract:

Hence in the planned thesis, a carbon coating was produced on LiNi0.6Mn0.2Co0.2O2 (NMC622) material. Carbon coatings with two different precursors were performed namely furfuryl alcohol-based (FA) and resorcinol formaldehyde-based (RF) ones. Owing to the better physical and electrochemical properties, FA-based coating was considered for further detailed study. The coating carried out via acid-catalyzed polymerization of furfuryl alcohol, followed by a calcination step. The effect of calcination on the thickness of the coating and electrochemical behavior is in detailed investigated. The coating with ~ 15-20 nm thick carbon layer on top of NMC622, resulted in ~ 8% improved long-term (400 cycles) capacity retention and ~ 50% enhanced high-power (10C) discharge performances compared to uncoated ones. Nevertheless, to understand the effect of calcination on the NMC622, the samples calcined in the same way without coating are carried out and found to improve the performances due to enhanced crystallinity by removal of surface impurities.

Further, to achieve better electrode processing, aqueous-based slurry preparation of uncoated and carbon-coated NMC622 is carried out and compared with the conventional N-methyl-pyrrolidone (NMP) slurry processing. Here the coated materials show better processability i.e. the fabricated electrodes do not show any physical or mechanical instabilities due to their good control over the pH value. The electrochemical tests such as long-term charge-discharge and C-rate performance showed improvement in the carbon coated samples when compared with the uncoated ones. Furthermore, a psuedo-2D isothermal model of uncoated/coated NMC622 was constructed based on the Doyle-Fuller-Newman model. The simulated charge-discharge performance obtained for the uncoated and coated materials at a defined C-rate show an improvement in capacity for the surface coated NMC622 and supports the experimental results. Additionally, to understand the effect of carbon coating the particle vs. carbon coating on the electrode, the carbon coated NMC622 electrode were prepared using magnetron sputtering. The controlled carbon coating thickness of 4 nm, 8 nm, 16 nm, and 32 nm resulted in better electrochemical performances when compared to its uncoated pristine electrode. Especially, the 16 nm carbon coating showed better performances in long-term as well as C-rate analysis.

Additionally, the full cells of uncoated/coated NMC622 vs. graphite were fabricated at the coin cell level. The results showed better electrochemical performance of the coated material at 25°C and 60°C. Finally, to transfer the gained knowledge from the coin cells to a market near LIBs, laboratory prototype pouch cells of the coated and uncoated NMCs were fabricated and found to show good performance. However, to commercialize the technology further optimization of the process is desirable. In this way, the present thesis work shows material to lab prototype study of the surface coated NMC622.#

Wir freuen uns sehr über diesen großen Erfolg und wünschen Xue Zhang und Anish Raj Kathribail alles Gute für ihre weitere wissenschaftliche Laufbahn!