TY - JOUR AU - Zhang, X. AU - Turiansky, M.E. AU - Razinkovas, L. AU - Maciaszek, M. AU - Broqvist, P. AU - Yan, Q. AU - Lyons, J.L. AU - Dreyer, C.E. AU - Wickramaratne, D. AU - Gali, Ádám AU - Pasquarello, A. AU - Van de Walle, C.G. TI - First-principles calculations of defects and electron-phonon interactions: Seminal contributions of Audrius Alkauskas to the understanding of recombination processes JF - JOURNAL OF APPLIED PHYSICS J2 - J APPL PHYS VL - 135 PY - 2024 IS - 15 PG - 9 SN - 0021-8979 DO - 10.1063/5.0205525 UR - https://m2.mtmt.hu/api/publication/34832941 ID - 34832941 AB - First-principles calculations of defects and electron-phonon interactions play a critical role in the design and optimization of materials for electronic and optoelectronic devices. The late Audrius Alkauskas made seminal contributions to developing rigorous first-principles methodologies for the computation of defects and electron-phonon interactions, especially in the context of understanding the fundamental mechanisms of carrier recombination in semiconductors. Alkauskas was also a pioneer in the field of quantum defects, helping to build a first-principles understanding of the prototype nitrogen-vacancy center in diamond, as well as identifying novel defects. Here, we describe the important contributions made by Alkauskas and his collaborators and outline fruitful research directions that Alkauskas would have been keen to pursue. Audrius Alkauskas’ scientific achievements and insights highlighted in this article will inspire and guide future developments and advances in the field. © 2024 Author(s). LA - English DB - MTMT ER - TY - JOUR AU - Wilson, S.G. AU - Eaton, M.D. AU - Kópházi, József TI - Energy-Dependent, Self-Adaptive Mesh h(p)-Refinement of an Interior-Penalty Scheme for a Discontinuous Galerkin Isogeometric Analysis Spatial Discretization of the Multi-Group Neutron Diffusion Equation with Dual-Weighted Residual Error Measures JF - JOURNAL OF COMPUTATIONAL AND THEORETICAL TRANSPORT J2 - J COMPUT THEOR TRANSP PY - 2024 SN - 2332-4309 DO - 10.1080/23324309.2024.2334277 UR - https://m2.mtmt.hu/api/publication/34832886 ID - 34832886 N1 - Export Date: 3 May 2024 Correspondence Address: Wilson, S.G.; Nuclear Engineering Group, Exhibition Road, South Kensington, United Kingdom; email: seth.wilson16@imperial.ac.uk AB - Energy-dependent self-adaptive mesh refinement algorithms are developed for a symmetric interior-penalty scheme for a discontinuous Galerkin spatial discretization of the multi-group neutron diffusion equation using NURBS-based isogeometric analysis (IGA). The spatially self-adaptive algorithms employ both mesh (h) and polynomial degree (p) refinement. The discretized system becomes increasingly ill-conditioned for increasingly large penalty parameters; and there is no gain in accuracy for over penalization. Therefore, optimized penalty parameters are rigorously calculated, for general element types, from a coercivity analysis of the bilinear form. Local mesh refinement allows for a better allocation of computational resources; and thus, more accuracy per degree of freedom. Two a posteriori interpolation-based error measures are proposed. The first heuristically minimizes local contributions to the discretization error, which becomes competitive for global quantities of interest (QoIs). However, for localized QoIs, over energy-dependent meshes, certain multi-group components may become under-resolved. The second employs duality arguments to minimize important error contributions, which consistently and reliably reduces the error in the QoI. © 2024 The Author(s). Published with license by Taylor & Francis Group, LLC. LA - English DB - MTMT ER - TY - JOUR AU - Sebestény, Dániel István AU - Panka, István AU - Batki, Bálint TI - Automated group constant parameterization for low sample sizes using different Machine learning approaches JF - ANNALS OF NUCLEAR ENERGY J2 - ANN NUCL ENERGY VL - 204 PY - 2024 PG - 10 SN - 0306-4549 DO - 10.1016/j.anucene.2024.110560 UR - https://m2.mtmt.hu/api/publication/34832872 ID - 34832872 N1 - Budapest University of Technology and Economics, Institute of Nuclear Techniques, Hungary HUN-REN Centre for Energy Research, Hungary Export Date: 3 May 2024 CODEN: ANEND Correspondence Address: Sebestény, D.Konkoly-Thege Miklós út 29-33, Hungary; email: sebesteny.daniel@ek.hun-ren.hu AB - This paper deals with group constant parameterization, a necessary step to utilize the results of assembly-level neutronics calculations at the full-core level. The focus is on low sample size problems when the commonly used linear interpolation approach is inadequate, a typical situation of using Monte Carlo codes for group constant generation. This work presents a newly developed code package for automated group constant parameterization. It implements several machine learning regression models − including a novel polynomial regression algorithm − performs hyperparameter optimization and selects the best model based on a detailed evaluation. The applicability of the new code package is demonstrated in a case study for a VVER-1200 fuel assembly covering both normal operation and transient conditions. In this example, the novel polynomial regression model provides a 73 pcm average error in kinf that leads to reactivity coefficients well within the desired precision. © 2024 The Authors LA - English DB - MTMT ER - TY - JOUR AU - Itatani, Masaki AU - Onishi, Yuhei AU - Suematsu, Nobuhiko J. AU - Lagzi, István László TI - Periodic Precipitation in a Confined Liquid Layer JF - JOURNAL OF PHYSICAL CHEMISTRY LETTERS J2 - J PHYS CHEM LETT VL - 15 PY - 2024 SP - 4948 EP - 4957 PG - 10 SN - 1948-7185 DO - 10.1021/acs.jpclett.4c00832 UR - https://m2.mtmt.hu/api/publication/34830134 ID - 34830134 LA - English DB - MTMT ER - TY - GEN AU - Bálint, Péter AU - Terhesiu, Dalia TI - Generalized law of iterated logarithm for the Lorentz gas with infinite horizon PY - 2024 UR - https://m2.mtmt.hu/api/publication/34824198 ID - 34824198 LA - English DB - MTMT ER - TY - JOUR AU - Tóth, Boglárka AU - Farkas, D. G. AU - Amelin, K. AU - Rõõm, T. AU - Nagel, U. AU - Udvardi, L. AU - Szunyogh, L. AU - Rózsa, L. AU - Ito, T. AU - Bordács, Sándor TI - Terahertz spin-wave excitations in the transverse conical phase of BiFeO3 JF - PHYSICAL REVIEW B J2 - PHYS REV B VL - 109 PY - 2024 IS - 14 SN - 2469-9950 DO - 10.1103/PhysRevB.109.144424 UR - https://m2.mtmt.hu/api/publication/34823661 ID - 34823661 LA - English DB - MTMT ER - TY - JOUR AU - Møller, Frederik AU - Nagy, Botond AU - Kormos, Márton AU - Takács, Gábor TI - Dynamical separation of charge and energy transport in one-dimensional Mott insulators JF - PHYSICAL REVIEW B J2 - PHYS REV B VL - 109 PY - 2024 IS - 16 SN - 2469-9950 DO - 10.1103/PhysRevB.109.L161112 UR - https://m2.mtmt.hu/api/publication/34818513 ID - 34818513 N1 - Export Date: 3 May 2024 AB - One-dimensional Mott insulators can be described using the sine-Gordon model, an integrable quantum field theory that provides the low-energy effective description of several one-dimensional gapped condensed matter systems, including recent realizations with trapped ultracold atoms. Employing the theory of generalized hydrodynamics, we demonstrate that this model exhibits separation of the transport of topological charge vs energy. Analysis of the quasiparticle dynamics reveals that the mechanism behind the separation is the reflective scattering between topologically charged kinks/antikinks. The effect of these scattering events is most pronounced at strong coupling and low temperatures, where the distribution of quasiparticles is narrow compared to the reflective scattering amplitude. This effect results in a distinctively shaped “arrowhead” light cone for the topological charge. LA - English DB - MTMT ER - TY - JOUR AU - Aszódi, Attila TI - Nem akárhonnan érkezett reagálás: A kancellári irányítási modell megbukott JF - INDEX.HU J2 - INDEX.HU PY - 2024 SN - 1585-3241 UR - https://m2.mtmt.hu/api/publication/34817030 ID - 34817030 LA - Hungarian DB - MTMT ER - TY - GEN ED - Aszódi, Attila / Interviewed person AU - Somodi-Solymos, Eszter TI - Lesz alternatív üzemanyag-szállító az atomerőművek számára a piacon | GENERÁTOR PY - 2024 UR - https://m2.mtmt.hu/api/publication/34816929 ID - 34816929 LA - Hungarian DB - MTMT ER - TY - GEN AU - Aszódi, Attila TI - 236 ENPOL, Prof. Dr. Aszódi Attila előadása PY - 2024 UR - https://m2.mtmt.hu/api/publication/34816904 ID - 34816904 LA - Hungarian DB - MTMT ER -