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de Koster, P.B.J. (author), Wahls, S. (author)Lax-integrable partial differential equations (PDEs) can by definition be described through a compatibility condition between two linear operators. These operators are said to form a Lax pair for the PDE, which itself is usually nonlinear. Lax pairs are a very useful tool, but unfortunately finding them is a difficult problem in practice. In...journal article 2024
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Wang, Q. (author), Lechtenfeld, Oliver J. (author), Rietveld, L.C. (author), Schuster, Jonas (author), Ernst, Mathias (author), Hofman-Caris, Roberta (author), Kaesler, Jan (author), Wang, Chunmiao (author), Yang, Min (author), Yu, Jianwei (author), Zietzschmann, F.E. (author)Activated carbon is employed for the adsorption of organic micropollutants (OMPs) from water, typically present in concentrations ranging from ng L<sup>−1</sup> to μg L<sup>−1</sup>. However, the efficacy of OMP removal is considerably deteriorated due to competitive adsorption from background dissolved organic matter (DOM), present at...journal article 2024
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Tang, Hongyu (author), Shi, Weiqi (author), Zhang, Rongjun (author), Fan, J. (author), Zhang, Kouchi (author)Tungsten disulfide (WS2) has recently attracted considerable attention owing to its excellent physical, chemical, electronic, and optical properties, leading to increased research into its applications in electronic and optoelectronic devices. However, the oxidation of 2D material affects significantly its optical and electronic properties...conference paper 2024
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Apostolidis, P. (author), Porot, Laurent (author)Bituminous binders are foreseen as colloidal dispersed systems characterised by high chemical complexity containing a plethora of molecules classified into maltenes and asphaltenes. The effect of these fractions on the overall response of bituminous binders remains elusive. This research selected two binders from the same refinery but with...journal article 2023
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de Koster, P.B.J. (author), Wahls, S. (author)We present a fast method to calculate the significantly large solitonic components of signals with large time-bandwidth products governed by the nonlinear Schrödinger equation, for which the computation typically becomes prohibitively expensive and/or numerically unstable. We partition the full signal in both frequency and time to obtain...journal article 2023
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de Koster, P.B.J. (author), Schulz, Olaf (author), Koch, Jonas (author), Pachnicke, Stephan (author), Wahls, S. (author)We experimentally investigate the problem of monitoring the Kerr-nonlinearity coefficient $\gamma$ from transmitted and received data for a single-mode fiber link of 1600 km length. We compare the accuracy and speed of three different approaches. First, a standard split-step Fourier method is used to predict the output at various $\gamma$...journal article 2023
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Chimmalgi, S. (author), Wahls, S. (author)Riemann theta functions play a crucial role in the field of nonlinear Fourier analysis, where they are used to realize inverse nonlinear Fourier transforms for periodic signals. The practical applicability of this approach has however been limited since Riemann theta functions are multi-dimensional Fourier series whose computation suffers...journal article 2023
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Zhao, Wenzhao (author), Fan, Yuling (author), Wang, Hongjian (author), Gemmeke, Hartmut (author), van Dongen, K.W.A. (author), Hopp, Torsten (author), Hesser, Jürgen (author)Objective. The image reconstruction of ultrasound computed tomography is computationally expensive with conventional iterative methods. The fully learned direct deep learning reconstruction is promising to speed up image reconstruction significantly. However, for direct reconstruction from measurement data, due to the lack of real labeled...journal article 2023
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Lee, Y.C. (author), Brühl, M. (author), Wahls, S. (author)When a large number of solitons dominates the dynamics of a system, scientists describe this collective behaviour of solitons as a soliton gas. Soliton gases are currently the subject of intense practical and theoretical investigations. The existence of soliton gases has been confirmed in experiments, but is not clear what kind of sea states...conference paper 2023
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Zhao, Z. (author), Birke, Robert (author), Chen, Lydia Y. (author)An alternative method for sharing knowledge while complying with strict data access regulations, such as the European General Data Protection Regulation (GDPR), is the emergence of synthetic tabular data. Mainstream table synthesizers utilize methodologies derived from Generative Adversarial Networks (GAN). Although several state-of-the-art ...conference paper 2023
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Chimmalgi, S. (author)Due to the ever increasing global connectivity, the demand on the fiber-optic communication infrastructure is projected to keep increasing rapidly. A major factor currently limiting transmission capacity is the fiber nonlinearity. Some researchers have suggested the application of nonlinear Fourier transforms to exploit the fiber nonlinearity...doctoral thesis 2022
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Prins, Peter J. (author)<b>Research question</b><br/>The topic of this dissertation is the numerical computation of the forward and inverse Non-linear Fourier Transform (NFT) for the Korteweg–de Vries equation (KdV), for sampled signals that decay sufficiently fast on both sides. With NFTs certain non-linear Partial Differential Equations (PDEs) can be solved in a way...doctoral thesis 2022
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de Koster, P.B.J. (author), Brühl, M. (author), Wahls, S. (author)We propose a novel method to determine the average water depth from shallow, weakly nonlinear water waves that are approximated by the Korteweg-de Vries equation. Our identification method only requires free-surface measurements from two wave gauges aligned in the direction of wave propagation. The method we propose is based on comparing...conference paper 2022
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de Koster, P.B.J. (author), Koch, Jonas (author), Schulz, Olaf (author), Pachnicke, Stephan (author), Wahls, S. (author)Recently, a nonlinear Fourier transform-based Kerr-nonlinearity identification algorithm was demonstrated for a 1000 km NZDSF link with accuracy of 75%. Here, we demonstrate an accuracy of 99% over 1600 km SSMF. Reasons for improved accuracy are discussed.conference paper 2022
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Brühl, M. (author), Prins, Peter J. (author), Ujvary, Sebastian (author), Barranco, Ignacio (author), Wahls, S. (author), Liu, Philip L.-F. (author)In this paper, we study the propagation of bores over a long distance. We employ experimental data as input for numerical simulations using COULWAVE. The experimental flume is extended numerically to an effective relative length of x/h=3000, which allows all far-field solitons to emerge from the undular bore in the simulation data. We apply the...journal article 2022
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Prins, Peter J. (author), Wahls, S. (author)We propose a numerical algorithm that computes the eigenvalues of the Korteweg–de Vries equation (KdV) from sampled input data with vanishing boundary conditions. It can be used as part of the Non-linear Fourier Transform (NFT) for the KdV equation. The algorithm that we propose makes use of Sturm-Liouville (SL) oscillation theory to guaranty...journal article 2022
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Hajizad, O. (author), Kumar, A. (author), Petrov, R.H. (author), Sietsma, J. (author), Dollevoet, R.P.B.J. (author), Li, Z. (author)Microscopic stress and strain partitioning control the mechanical and damage behavior of multiphase steels. Using a combined numerical and experimental approach, local strain distributions and deformation localization are characterized in a carbide free bainitic steel produced by continuous cooling. The microstructure of the steel consists of...journal article 2022
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Grazian, F. (author), Shi, W. (author), Soeiro, Thiago B. (author), Dong, J. (author), Bauer, P. (author)When considering EV wireless charging that uses inductive power transfer with magnetic resonance, the coils’ current distortion must be minimized to guarantee compliance with the electromagnetic compatibility limits on the radiated magnetic field set by the relevant industrial standards. This paper analyzes the current distortion caused by...conference paper 2022
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Grillo Peternella, F. (author)Photonic sensors have recently attracted much attention in both industry and academia. High accuracy, low weight and the possibility of building a large sensor network are key benefits of photonic sensors. Another benefit is installing optical sensors in harsh environments where electronic sensors' usage is not plausible: aerospace applications...doctoral thesis 2021
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Hajizad, O. (author)In this PhD thesis, we investigated possible steel candidates for use in railway crossings in order to reduce the damage in them. Pearlitic R350HT together with Bainitic grades including CrB, B1400 and carbide free B360 were investigated for their mechanical properties such as ultimate strength, yield strength, ductility and hardness. The...doctoral thesis 2021