检索结果-内蒙古大学图书馆

Moduli spaces and breather dynamics of analytic solutions in chiral magnets without Heisenberg exchange interaction

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Barton-Singer, Bruno Bolognesi, Stefano Gudnason, Sven Bjarke Menta, Roberto Institute of Applied and Computational Mathematics Foundation for Research and Technology - Hellas Heraklion700 13 Greece Department of Physics "E. Fermi" University of Pisa INFN Sezione di Pisa Largo Pontecorvo 3 Ed. C Pisa56127 Italy Institute of Contemporary Mathematics School of Mathematics and Statistics Henan University Henan Kaifeng475004 China Scuola Normale Superiore Piazza dei Cavalieri 7 Laboratorio NEST Piazza S. Silvestro 12 Pisa56127 Italy

We investigate the special case of the chiral magnet with vanishing Heisenberg exchange energy, whose axisymmetric Skyrmion solution has previously been found. The dynamical equations of this model look like inviscid fluid flow, and by investigating path-lines of this flow we can construct explicit static and dynamic solutions. We find an infinite-dimensional family of static Skyrmions that are related to the axisymmetric Skyrmion by co-ordinate transformations thus discovering a new moduli space, and further infinite-dimensional families of axisymmetric and non-axisymmetric breather-like supercompactons. We call the maps generating such moduli space "contour-preserving" maps. Copyright © 2024, The Authors. All rights reserved.

关键词： Exchange interactions

Day-Ahead Forecasting of Solar Irradiance & PV Power Output Through Statistical Machine Learning Methods

学校读者我要写书评

暂无评论

Day-Ahead Forecasting of Solar Irradiance & PV Power Output ...

Saudi Arabia Smart Grid Conference (SASG)

作者： Yiannis Kamarianakis Yannis Pantazis Evangelia Kalligiannaki Theodoros D. Katsaounis Konstantinos Kotsovos Issam Gereige Marwan Abdullah Aqil Jamal Athanasios Tzavaras Data Science Group Institute of Applied and Computational Mathematics Foundation for Research and Technology-Hellas Greece Dept. of Mathematics and Applied Mathematics University of Crete Greece Carbon Management Division Saudi Aramco R&D Center Dhahran Saudi Arabia Computer Electrical and Mathematical Sciences and Engineering Division King Abdullah University of Science and Technology (KAUST) Thuwal Saudi Arabia

Energy production from solar photovoltaic (PV) plants is unpredictable, mainly due to the stochastic formation and movement of clouds or aerosol - dust particles which scatter or disperse solar radiation. Accurate forecasts of PV output are essential to Distribution and Transportation System Operators as they assist efficient solar energy trading and management of electricity grids. This work evaluates an autoregressive, computationally-light KNN-regression scheme (TSFKNN) for hourly, day-ahead forecasts of solar irradiance and energy yield of various PV technologies. The model is being tested and validated using data measured in Thuwal, Saudi Arabia. The available measured records span a 60-month period. The developed forecasting models are designed for online systems and provide increased levels of accuracy and low computational cost. Several parametric and nonparametric specifications, coupled with conventional versus outlier-robust estimation procedures are tested, in order to derive an optimal month-specific daily profile (MDP). Current results demonstrate that including intraday variability to the monthly-based irradiance models achieve improved predictive accuracy between 10% and 25% on average.

关键词：

Socio-Economic Assessment of the Impact of the Anticipated Sea Level Rise on Peloponnese Coast (Eastern Mediterranean)

学校读者我要写书评

暂无评论

SSRN

SSRN 2023年

作者： Poulos, Serafeim E. Karditsa, Aikaterini Coastal & Marine Research Laboratory Institute of Applied and Computational Mathematics Foundation for Research and Technology-Hellas PO Box 1385 Crete Heraklion70013 Greece Laboratory of Physical Geography Section of Geography & Climatology Faculty of Geology & Geoenvironment National and Kapodistrian University of Athens Panepistimoupolis-Zografou TK Attiki15784 Greece Department of Port Management and Shipping National and Kapodistrian University of Athens Evripos Campus Greece

The 1455 km length of the coastline of the Peloponnese (southern Greece) is characterized by a variety of coastal landforms, mainly as a result of its geodynamic evolution and the prevailing coastal hydrodynamic conditions. In terms of coastal exposure to sea level rise highly vulnerable coasts include all types of depositional formations (beaches, deltas, lagoons), while low/very low vulnerability present rocky coasts with cliffs. The assessment of expected shoreline retreat due to sea level rise (SLR) by 2100 in 15 beach zones, representative of the 192 most touristic beaches in the Peloponnese, corresponds to approximately total loss of 37% (SSP1-2.6), 45% (SSP2-4.5) and 57% (SSP5-8.5). Adaptation to climate change impact could be achieved by applying Article 8 of Protocol 7 of the Barcelona Convention "Protocol on Integrated Coastal Zone Management in the Mediterranean", which asks for the identification of a zone at least 100 m wide from the higher limit of wave runup). In the case of Peloponnese this zone covers an area of 135 km2, consisting mostly of forests and grasslands (43.5%), cultivated land (30%), followed by wetlands (11.7%), artificial constructions (11.6%) and beaches/ dunes (3.1%);its integrated economic value in the range of 980 - 1240 Euro/m2. © 2023, The Authors. All rights reserved.

关键词： Beaches

Uniqueness for Some Mixed Problems of Nonlinear Elastostatics

学校读者我要写书评

暂无评论

arXiv 2025年

作者： Rosakis, Phoebus Department of Mathematics and Applied Mathematics University of Crete Crete Heraklion70013 Greece Institute for Applied and Computational Mathematics Foundation of Research and Technology-Hellas Crete Heraklion70013 Greece Center of Mediocrity for Antiquated Materials Mitato Crete72300 Greece

We show that certain mixed displacement/traction problems (including live pressure tractions) of nonlinear elastostatics that are solved by a homogeneous deformation, admit no other classical equilibrium solution under suitable constitutive inequalities and domain boundary restrictions. This extends a well known theorem of Knops and Stuart on the pure displacement problem. © 2025, CC BY.

关键词： Digital arithmetic

MAXIMALITY AND COMPLETENESS OF ORTHOGONAL EXPONENTIALS ON THE CUBE

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Kolountzakis, Mihail N. Lev, Nir Matolcsi, Máté Department of Mathematics and Applied Mathematics University of Crete Voutes Campus Heraklion70013 Greece Institute of Computer Science Foundation of Research and Technology Hellas N. Plastira 100 Vassilika Vouton Heraklion700 13 Greece Department of Mathematics Bar-Ilan University Ramat-Gan5290002 Israel HUN-REN Alfréd Rényi Mathematical Institute Reáltanoda utca 13-15 BudapestH-1053 Hungary Department of Analysis Hungary Operations Research Institute of Mathematics Budapest University of Technology and Economics Műegyetem rkp. 3. BudapestH-1111 Hungary

It is possible to have a packing by translates of a cube that is maximal (i.e. no other cube can be added without overlapping) but does not form a tiling. In the long running analogy of packing and tiling to orthogonality and completeness of exponentials on a domain, we pursue the question whether one can have maximal orthogonal sets of exponentials for a cube without them being complete. We prove that this is not possible in dimensions 1 and 2, but is possible in dimensions 3 and higher. We provide several examples of such maximal incomplete sets of exponentials, differing in size, and we raise relevant questions. We also show that even in dimension 1 there are sets which are spectral (i.e. have a complete set of orthogonal exponentials) and yet they also possess maximal incomplete sets of orthogonal *** Codes 42B10, 42C05, 52C22 © 2024, CC BY.

关键词： Geometry

Optimization of Crop Yields in Sustainable Agriculture: Application of Big Data Analytics and Artificial Intelligence

学校读者我要写书评

暂无评论

Remote Sensing in Earth Systems Sciences 2025年第2期8卷 375-386页

作者： Nimma, Divya Dhanke, Jyoti A. Murthy, G.S.N. Khandekar, Sachin Dadu Hymavathi, J. Jangir, Pradeep Singh, Mahesh Department of Computational Science University of Southern Mississippi Hattiesburg 39406 MS United States Department of Engineering Science (Mathematics) Bharati Vidyapeeth’s College of Engineering Lavale Maharashtra Pune India Department of CSE Aditya University Surampalem India Department of Civil Engineering Sinhgad College of Engineering Maharashtra Pune India Department of CSE Koneru Lakshmaiah Education Foundation Andhra Pradesh Vaddeswaram India Department of Biosciences Saveetha School of Engineering Saveetha Institute of Medical and Technical Sciences Chennai India Hourani Center for Applied Scientific Research Al-Ahliyya Amman University Amman 19328 Jordan Department of Robotics and Automation Symbiosis Institute of Technology Pune Campus Symbiosis International (Deemed University) Pune India

Making informed economic decisions based on agricultural data is challenging without proper crop management. Data has become the single most important part of modern farming, and its rapid evolution is a major contributor to the rise of “smart farming.” Using sensors to gather objective data with the end aim of increasing productivity and sustainability has several advantages. Information that might boost productivity while decreasing resource waste and pollution levels is essential for managed farms. The cornerstone of future sustainable farming will be data-driven agriculture using robotic solutions based on AI-based techniques. This paper examines the current state of advanced farm management systems, discussing topics like data acquisition in crop fields and variable rate applications, to assist farmers in saving money, protecting the environment, and transforming food production so that it can sustainably keep up with the expected increase in population. The advent of machine learning, big data technologies, and high-performance computers has opened up new avenues for data-intensive research in the interdisciplinary subject of agro technology. These avenues of exploration have been aided by the development of more capable computers. A comprehensive literature review on the issue of the applications of machine learning in agricultural manufacturing is provided in this research. Machine learning has shown its utility in agriculture via two applications: filtering and categorizing products. The use of machine learning on sensor data is transforming conventional farm management systems into AI-enabled programs. These services provide farmers instantaneous, complete access to ideas and insights that may guide their decisions. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025.

关键词： Artificial intelligence Big data analytics Optimize crop yields Sustainable agriculture

Cauchy robust principal component analysis with applications to high-deimensional data sets

学校读者我要写书评

暂无评论

arXiv 2022年

作者： Fayomi, Ayisha Pantazis, Yannis Tsagris, Michail Wood, Andrew T.A. Department of Statistics King Abdulaziz University Jeddah Saudi Arabia Institute of Applied & Computational Mathematics Foundation for Research & Technology - Hellas Heraklion Greece Department of Economics University of Crete Gallos Campus Rethymnon Greece Research School of Finance Actuarial Studies & Statistics Australian National University Canberra Australia

Principal component analysis (PCA) is a standard dimensionality reduction technique used in various research and applied fields. From an algorithmic point of view, classical PCA can be formulated in terms of operations on a multivariate Gaussian likelihood. As a consequence of the implied Gaussian formulation, the principal components are not robust to outliers. In this paper, we propose a modified formulation, based on the use of a multivariate Cauchy likelihood instead of the Gaussian likelihood, which has the effect of robustifying the principal components. We present an algorithm to compute these robustified principal components. We additionally derive the relevant influence function of the first component and examine its theoretical properties. Simulation experiments on high-dimensional datasets demonstrate that the estimated principal components based on the Cauchy likelihood outperform or are on par with existing robust PCA techniques. © 2022, CC BY.

关键词： Principal component analysis

From order to disorder of alkanethiol SAMs on complex Au (211), (221) and (311) surfaces: Impact of the substrate

学校读者我要写书评

暂无评论

arXiv 2021年

作者： Stefanakis, Dimitrios Harmandaris, Vagelis Kopidakis, Georgios Remediakis, Ioannis Department of Materials Science & Technology University of Crete Vassilika Voutes Heraklion700 13 Greece Department of Mathematics & Applied Mathematics - University of Crete Vassilika Voutes Heraklion700 13 Greece Institute of Applied & Computational Mathematics Foundation for Research and Technology-Hellas 711 10 Heraklion Greece Computation-Based Science and Technology Research Center The Cyprus Institute Nicosia2121 Cyprus Institute of Electronic Structure and Laser Foundation for Research and Technology-Hellas 711 10 Heraklion Greece

We investigate the impact of the substrate on the structural properties and the morphology of alkanethiol self-assembled monolayers (SAMs) on gold, using first principles calculations and atomistic molecular dynamics simulations. We consider hexadecanethiols on Au(211), Au(221) and Au(311) surfaces which contain few-atom wide terraces separated by monoatomic steps similar to the complex Au surfaces used in experiments. The structure of the SAMs is probed via several structural properties including tilt angles, mean C atom heights from the surface, precession angles, gauche defects, gyration tensors and relative shape anisotropy. Comparing these properties to those of the well-studied SAMs on Au(111), we observe similarities but also striking differences. A clear order to disorder transition is observed by changing the substrate: well-ordered SAMs on (111) and (211) surfaces become mixed ordered-disordered structures on (311) and fully disordered on (221). The presence of steps on the Au surfaces also results in preferential tilt orientations with long-range order. Our results show that in addition to the expected grafting density dependence, the transition from order to disorder crucially depends on substrate morphology. The onset of ordering behavior is related to the atomic structure of the surface. The key parameter that affects long-range order is the energy for changing the dihedral angle between Au-S-C(1) − C(2) of the adsorbed alkanethiol. © 2021, CC BY.

关键词： Molecular dynamics

Inverted pin beams for robust long-range propagation through atmospheric turbulence

学校读者我要写书评

暂无评论

arXiv 2023年

作者： Droulias, Sotiris Loulakis, Michalis Papazoglou, Dimitris G. Tzortzakis, Stelios Chen, Zhigang Efremidis, Nikolaos K. Institute of Applied and Computational Mathematics FORTH Crete Heraklion70013 Greece Department of Digital Systems University of Piraeus Piraeus18534 Greece Institute of Electronic Structure and Laser Foundation for Research and Technology - Hellas P.O. Box 1527 Crete Heraklion71110 Greece Department of Materials Science and Technology University of Crete Crete Heraklion700 13 Greece MOE Key Laboratory of Weak-Light Nonlinear Photonics TEDA Applied Physics Institute School of Physics Nankai University Tianjin300457 China Collaborative Innovation Center of Extreme Optics Shanxi University Shanxi Taiyuan030006 China Department of Applied Mathematics University of Crete Heraklion71409 Greece

We introduce a new class of optical beams, which feature a spatial profile akin to an "inverted pin". In particular, we asymptotically find that close to the axis the transverse amplitude profile of such beams takes the form of a Bessel function with width that gradually increases during propagation. We examine numerically the behavior of such inverted pin beams in turbulent environments as measured via the scintillation index, and show that they outperform Gaussian beams (collimated and focused) as well as Bessel beams and regular pin beams, which are all optimized, especially in the moderate and strong fluctuation regimes. Copyright © 2023, The Authors. All rights reserved.

关键词： Gaussian beams