cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Spatial Wideband Channel Estimation for MmWave Massive MIMO Systems with Hybrid Architectures and Low-Resolution ADCs
Creators: name: Kim, In-soo
name: Choi, Junil
Publisher: name: arXiv
Year: 2021
Subjects: subject: Signal Processing (eess.SP)
subject: Information Theory (cs.IT)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Computer and information sciences

description: In this paper, a channel estimator for wideband millimeter wave (mmWave) massive multiple-input multiple-output (MIMO) systems with hybrid architectures and low-resolution analog-to-digital converters (ADCs) is proposed. To account for the propagation delay across the antenna array, which cannot be neglected in wideband mmWave massive MIMO systems, the discrete time channel that models the spatial wideband effect is developed. Also, the training signal design that addresses inter-frame, inter-user, and inter-symbol interferences is investigated when the spatial wideband effect is not negligible. To estimate the channel parameters over the continuum based on the maximum a posteriori (MAP) criterion, the Newtonized fully corrective forward greedy selection-cross validation-based (NFCFGS-CV-based) channel estimator is proposed. NFCFGS-CV is a gridless compressed sensing (CS) algorithm, whose termination condition is determined by the CV technique. The CV-based termination condition is proved to achieve the minimum squared error (SE). The simulation results show that NFCFGS-CV outperforms state-of-the-art on-grid CS-based channel estimators.
description: to appear in IEEE Transactions on Wireless Communications
Sonnenfleckenzeichnung, unnummeriert.
Zeichnung von Flecken und Fackelflächen zur Ermittlung der Sonnenaktivität am 25.12.1951, erstellt am Sonnenobservatorium Kanzelhöhe, Kärnten
Creators: name: [s.n.]
Publisher: name: [s.n.]
Year: 1951

description: Bleistiftzeichnung mit Tinte und Bleistift, erstellt als Zeichnung nach eigener Vorlage im Sonnenobservatorium Kanzelhöhe in Sattendorf, Österreich. Instrument: Heliostat mit Refraktor Eigenbau (Öffnung 110mm, f = 1650mm, projiziertes Sonnenbild D = 25cm)
Sonnenfleckenzeichnung Nr. 18011.
Zeichnung von Flecken und Fackelflächen zur Ermittlung der Sonnenaktivität am 31.12.1951, erstellt von Helmut Müller
Creators: name: [s.n.]
Publisher: name: [s.n.]
Year: 1951

description: Bleistiftzeichnung mit Tinte und Farbstift überschrieben, erstellt als Projektionsbildzeichnung in der Eidgenössischen Sternwarte Zürich. Instrument: Kern-Merz-Refraktor.
Die Beobachtungen zu Einzelflecken und zu Sonnenfleckengruppen wurden mit Bleistift auf einem Vordruck eingetragen. Unter Umständen sind Angaben zu Protuberanzen vermerkt
Security in Quantum Cryptography
Creators: name: Portmann, Christopher
name: Renner, Renato
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: Cryptography and Security (cs.CR)
subject: Information Theory (cs.IT)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: Quantum cryptography exploits principles of quantum physics for the secure processing of information. A prominent example is secure communication, i.e., the task of transmitting confidential messages from one location to another. The cryptographic requirement here is that the transmitted messages remain inaccessible to anyone other than the designated recipients, even if the communication channel is untrusted. In classical cryptography, this can usually only be guaranteed under computational hardness assumptions, e.g., that factoring large integers is infeasible. In contrast, the security of quantum cryptography relies entirely on the laws of quantum mechanics. Here we review this physical notion of security, focusing on quantum key distribution and secure communication.
description: 63 pages, 34 figures. In submission to RMP. Partly based on arXiv:1409.3525. v2: new references and minor edits
Sonnenfleckenzeichnung Nr. 18001.
Zeichnung von Flecken und Fackelflächen zur Ermittlung der Sonnenaktivität am 16.12.1951, erstellt von Adolf Lemans
Creators: name: [s.n.]
Publisher: name: [s.n.]
Year: 1951

description: Bleistiftzeichnung mit Tinte und Farbstift überschrieben, erstellt als Projektionsbildzeichnung in der Eidgenössischen Sternwarte Zürich. Instrument: Kern-Merz-Refraktor.
Die Beobachtungen zu Einzelflecken und zu Sonnenfleckengruppen wurden mit Bleistift auf einem Vordruck eingetragen. Später wurden ergänzende Angaben aufgrund auswärtiger Beobachtungen direkt auf der Fleckenzeichnung hinzugefügt. Unter Umständen sind Angaben zu Protuberanzen vermerkt
Sonnenfleckenzeichnung, unnummeriert.
Zeichnung von Flecken und Fackelflächen zur Ermittlung der Sonnenaktivität am 06.11.1951, erstellt von K. am Skalnate Pleso Observatorium
Creators: name: [s.n.]
Publisher: name: [s.n.]
Year: 1951

description: Bleistiftzeichnung mit Tinte und Farbstift, erstellt als Zeichnung nach eigener Vorlage am Skalnate Pleso Observatorium. Es sind zudem statistische Angaben für die Bestimmung der Fleckenrelativzahl notiert. Instrument: unbekannt, Sonnenbild D = 25 cm
Linear modal instabilities around post-stall swept finite-aspect ratio wings at low Reynolds numbers
Creators: name: Burtsev, Anton
name: He, Wei
name: Hayostek, Shelby
name: Zhang, Kai
name: Theofilis, Vassilios
name: Taira, Kunihiko
name: Amitay, Michael
Publisher: name: arXiv
Year: 2021
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: Linear modal instabilities of flow over finite-span untapered wings have been investigated numerically at Reynolds number 400, at a range of angles of attack and sweep on two wings having aspect ratios 4 and 8. Base flows have been generated by direct numerical simulation, marching the unsteady incompressible three-dimensional Navier-Stokes equations to a steady state, or using selective frequency damping to obtain stationary linearly unstable flows. Unstable three-dimensional linear global modes of swept wings have been identified for the first time using spectral-element time-stepping solvers. The effect of the wing geometry and flow parameters on these modes has been examined in detail. An increase of the angle of attack was found to destabilize the flow, while an increase of the sweep angle had the opposite effect. On unswept wings, TriGlobal analysis revealed that the most unstable global mode peaks in the midspan region of the wake; the peak of the mode structure moves towards the tip as sweep is increased. Data-driven analysis was then employed to study the effects of wing geometry and flow conditions on the nonlinear wake. On unswept wings, the dominant mode at low angles of attack is a Kelvin-Helmholtz-like instability, qualitatively analogous with global modes of infinite-span wings under same conditions. At higher angles of attack and moderate sweep angles, the dominant mode is a structure denominated the interaction mode. At high sweep angles, this mode evolves into elongated streamwise vortices on higher aspect ratio wings, while on shorter wings it becomes indistinguishable from tip-vortex instability.
description: 41 pages, 27 figures
malachisis
Creators: name: Smith, F.
Publisher: name: Zenodo
Year: 1859
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Andrenidae

description: 1. Prosopis malachisis.
P. nigro-caeruleo-viridis, nitida et delicatule punctata; alis hyalinis.
Female. Length 4 1 / 2 lines. Deep blue-green, with tints of purple in certain lights, particularly on the head, the clypeus with a central longitudinal ridge, its anterior margin slightly emarginate; the flagellum rufo-piceous beneath, the ocelli white. Thorax: the wings hyaline and brilliantly iridescent; the legs dark rufo-piceous with a bright purple tinge. Abdomen delicately punctured, the head and thorax more strongly so; the latter with a semicircular enclosed space at its base, which is smooth and shining.
Hab. Key Island.
description: Published as part of Smith, F., 1859, Catalogue of hymenopterous insects collected by Mr. A. R. Wallace at the Islands of Aru and Key., pp. 132-158 in Journal of the Proceedings of the Linnean Society of London, Zoology 3 on page 132
Sonnenfleckenzeichnung unnummeriert, einen Zürcher Lückentag ergänzend.
Zeichnung von Flecken und Fackelflächen zur Ermittlung der Sonnenaktivität am 25.10.1951, erstellt von Horst Künzel, Astrophysikalisches Observatorium in Potsdam
Creators: name: [s.n.]
Publisher: name: [s.n.]
Year: 1951

description: Bleistiftzeichnung mit Tinte und Bleistift, erstellt als Zeichnung nach eigener Vorlage im Astrophysikalischen Observatorium in Potsdam. Instrument: Astrograph
Sonnenfleckenzeichnung, unnummeriert.
Zeichnung von Flecken und Fackelflächen zur Ermittlung der Sonnenaktivität am 10.11.1951, erstellt von Gaston Coutrez, Observatoire Royal de Belgique in Uccle
Creators: name: [s.n.]
Publisher: name: [s.n.]
Year: 1951

description: Bleistiftzeichnung mit Tinte und Farbstift, erstellt als Zeichnung nach eigener Vorlage in Uccle.
Instrument: Merz-Grubb Refraktor Teleskop (Öffnung 160 mm, f = 2450 mm, projiziertes Sonnenbild D = 25 cm)
Sonnenfleckenzeichnung Nr. 17948.
Zeichnung von Flecken und Fackelflächen zur Ermittlung der Sonnenaktivität am 11.10.1951, erstellt von Helmut Müller
Creators: name: [s.n.]
Publisher: name: [s.n.]
Year: 1951

description: Bleistiftzeichnung mit Tinte und Farbstift überschrieben, erstellt als Projektionsbildzeichnung in der Eidgenössischen Sternwarte Zürich. Instrument: Kern-Merz-Refraktor.
Die Beobachtungen zu Einzelflecken und zu Sonnenfleckengruppen wurden mit Bleistift auf einem Vordruck eingetragen. Unter Umständen sind Angaben zu Protuberanzen vermerkt
Sonnenfleckenzeichnung, unnummeriert.
Zeichnung von Flecken und Fackelflächen zur Ermittlung der Sonnenaktivität am 10.11.1951, erstellt von Wolfgang Gleissberg an der Universitätssternwarte Istanbul
Creators: name: [s.n.]
Publisher: name: [s.n.]
Year: 1951

description: Bleistiftzeichnung mit Tinte und Bleistift, erstellt als Zeichnung nach eigener Vorlage am Istanbul Universitesi Observatuari, Beyazit (Istanbul). Instrument: Zeiss Refraktor Teleskop (Öffnung 130 mm, f = 2000 mm, projiziertes Sonnenbild D = 25 cm)
An Attempt to Improve Understanding of the Physics behind Superconductor Phase Transitions and Stability
Creators: name: Reiss, Harald
Publisher: name: arXiv
Year: 2021
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Under disturbances, superconductors may experience sudden, most undesirable phase transitions (quench) from superconducting to normal conducting state. Quench may lead to damage or even to catastrophic conductor failure. A superconductor is stable if it does not quench. Exact determination of superconductor transient, resistive states (flux flow, Ohmic) thus is mandatory to safely avoid quench. This request sharp comparison of local, transient conductor temperature and current transport density with local values of critical superconductor temperature, TCrit, and critical current density, JCrit, and the latter is a strong function of temperature. Numerical, Finite Element simulations reported previously and in this paper have provided the requested, transient temperature distribution; under disturbances, this distribution may strongly be non-uniform. But what happens if the other variable, TCrit, might not uniquely be defined? A multi-physics model (fractional parentage, Pauli selection rule, time of flight-concept with a mediating Boson, the Yukawa model and the uncertainty principle) provides relaxation time at which TCrit, as the thermodynamic, equilibrium state, finally would be obtained. But relaxation time diverges the closer the electron system approaches the phase transition, which questions existence of uniquely defined TCrit within finite process time. In this paper, focus is on multiple internal heat transfer (solid conduction and, in thin films, radiation), a suggested operator method to solve the incompleteness problem of radiative transfer, and time dependence of the order parameter obtained from the quantum-mechanical model. Traditional stability models cannot provide this information.
description: Manuscript 54 p. (including refs list), 14 Figs (1a-c to 14, of which Figs 10a-c to 14 in Appendices 1 to 4, 23 Refs. No changes of Metadata and Categories. Results and conclusions same as before. No errors to be corrected; no changes within manuscript except for more comments, stylistic improvements. Paper originally submitted to Cryogenics, after requested (minor) revisions still under review
Sonnenfleckenzeichnung Nr. 17944.
Zeichnung von Flecken und Fackelflächen zur Ermittlung der Sonnenaktivität am 05.10.1951, erstellt von Helmut Müller
Creators: name: [s.n.]
Publisher: name: [s.n.]
Year: 1951

description: Bleistiftzeichnung mit Tinte und Farbstift überschrieben, erstellt als Projektionsbildzeichnung in der Eidgenössischen Sternwarte Zürich. Instrument: Kern-Merz-Refraktor.
Die Beobachtungen zu Einzelflecken und zu Sonnenfleckengruppen wurden mit Bleistift auf einem Vordruck eingetragen. Später wurden ergänzende Angaben aufgrund auswärtiger Beobachtungen direkt auf der Fleckenzeichnung hinzugefügt. Unter Umständen sind Angaben zu Protuberanzen vermerkt
Nomia cincta
Creators: name: Smith, F.
Publisher: name: Zenodo
Year: 1859
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Halictidae
Nomia
Nomia cincta

description: 1. Nomia cincta.
N. nigra, capite thoraceque punctatis, pedibus ferrugineis; segmentis abdominis apice fulvo-testaceo late fasciatis.
Female. Length 5 lines. Black: the two basal joints of the flagellum, the apical margin of the clypeus, the labrum, mandibles, and legs ferruginous; the wings fulvo-hyaline, the nervures ferruginous, the tegulae more or less rufo-testaceous; the sides of the metathorax with tufts of pale fulvous pubescence and the floccus on the posterior femora of the same colour, the tibiae and tarsi with short ferruginous pubescence. Abdomen shining, the apical margins of the segments broadly fulvo-testaceous, very bright, having a golden lustre. Hab. Key Island.
description: Published as part of Smith, F., 1859, Catalogue of hymenopterous insects collected by Mr. A. R. Wallace at the Islands of Aru and Key., pp. 132-158 in Journal of the Proceedings of the Linnean Society of London, Zoology 3 on page 132
Sonnenfleckenzeichnung unnummeriert, einen Zürcher Lückentag ergänzend.
Zeichnung von Flecken und Fackelflächen zur Ermittlung der Sonnenaktivität am 08.11.1951, erstellt von K. am Skalnate Pleso Observatorium
Creators: name: [s.n.]
Publisher: name: [s.n.]
Year: 1951

description: Bleistiftzeichnung mit Tinte und Farbstift, erstellt als Zeichnung nach eigener Vorlage am Skalnate Pleso Observatorium. Es sind zudem statistische Angaben für die Bestimmung der Fleckenrelativzahl notiert. Instrument: unbekannt, Sonnenbild D = 25 cm
Post-quantum steering is a stronger-than-quantum resource for information processing
Creators: name: Cavalcanti, Paulo J.
name: Selby, John H.
name: Sikora, Jamie
name: Galley, Thomas D.
name: Sainz, Ana Belén
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We present the first instance where post-quantum steering is a stronger-than-quantum resource for information processing -- remote state preparation. In addition, we show that the phenomenon of post-quantum steering is not just a mere mathematical curiosity allowed by the no-signalling principle, but it may arise within compositional theories beyond quantum theory, hence making its study fundamentally relevant. We show these results by formulating a new compositional general probabilistic theory -- which we call Witworld -- with strong post-quantum features, which proves to be a intuitive and useful tool for exploring steering and its applications beyond the quantum realm.
description: 9 pages, loads of diagrams. Comments welcome. Latest version: published version
Sonnenfleckenzeichnung Nr. 17976.
Zeichnung von Flecken und Fackelflächen zur Ermittlung der Sonnenaktivität am 15.11.1951, erstellt von Helmut Müller
Creators: name: [s.n.]
Publisher: name: [s.n.]
Year: 1951

description: Bleistiftzeichnung mit Tinte und Farbstift überschrieben, erstellt als Projektionsbildzeichnung in der Eidgenössischen Sternwarte Zürich. Instrument: Kern-Merz-Refraktor.
Die Beobachtungen zu Einzelflecken und zu Sonnenfleckengruppen wurden mit Bleistift auf einem Vordruck eingetragen. Unter Umständen sind Angaben zu Protuberanzen vermerkt
Singular Euler-Maclaurin expansion on multidimensional lattices
Creators: name: Buchheit, Andreas A.
name: Keßler, Torsten
Publisher: name: arXiv
Year: 2021
Subjects: subject: Numerical Analysis (math.NA)
subject: Mathematical Physics (math-ph)
subject: Number Theory (math.NT)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 65B1, 540H05 (Primary) 46F10, 35B65, 11E45 (Secondary)

description: We extend the classical Euler-Maclaurin expansion to sums over multidimensional lattices that involve functions with algebraic singularities. This offers a tool for the precise quantification of the effect of microscopic discreteness on macroscopic properties of a system. First, the Euler-Maclaurin summation formula is generalised to lattices in higher dimensions, assuming a sufficiently regular summand function. We then develop this new expansion further and construct the singular Euler-Maclaurin (SEM) expansion in higher dimensions, an extension of our previous work in one dimension, which remains applicable and useful even if the summand function includes a singular function factor. We connect our method to analytical number theory and show that all operator coefficients can be efficiently computed from derivatives of the Epstein zeta function. Finally we demonstrate the numerical performance of the expansion and efficiently compute singular lattice sums in infinite two-dimensional lattices, which are of high relevance in solid state and quantum physics. An implementation in Mathematica is provided online along with this article.
Single Harmonic-based Narrowband Magnetic Particle Imaging
Creators: name: Janssen, Klaas-Julian
name: Schilling, Meinhard
name: Ludwig, Frank
name: Zhong, Jing
Publisher: name: arXiv
Year: 2021
Subjects: subject: Medical Physics (physics.med-ph)
subject: FOS: Physical sciences

description: Visualization of the in vivo spatial distribution of superparamagnetic iron oxide nanoparticles (SPIONs) is crucial to biomedicine. Magnetic particle imaging (MPI) is one of the most promising approaches for direct measurements of the SPION distribution. In this paper, we systematically investigate a single-harmonic-based narrowband MPI approach. Herein, only the 3rd harmonic at 15 kHz of the SPION signal induced in an excitation magnetic field of 5 kHz is measured via a narrowband detection system for imaging during scanning a field-free-point in a field of view. Experiments on spot and line phantoms are performed to evaluate the spatial distribution by the assessment of the full width at half maximum and modulation transfer function at different excitation magnetic fields from 4 to 10 mT. Experimental results demonstrate that reconstructed images have a spatial resolution of 1.6 and 1.5 mm for a gradient field of 2.2 T/m and 4.4 T/m in x- and z-direction, respectively, at an excitation magnetic field of 4 mT. In terms of line gap, two lines with a gap of 0.5 mm are resolved. With increasing the excitation magnetic field to 10 mT, the spatial resolution gets worse to 2.4 and 2.0 mm in x- and z-direction, respectively. Moreover, the custom-built MPI scanner allows a limit of detection of 53 microgram (Fe)/mL (500 ng Fe weight) using perimag SPIONs. In addition, the excellent performance is demonstrated by imaging experiments on an "emg" logo phantom. We believe that the proposed narrowband MPI approach is a promising approach for SPION imaging.
Topological classification and diagnosis in magnetically ordered electronic materials
Creators: name: Peng, Bingrui
name: Jiang, Yi
name: Fang, Zhong
name: Weng, Hongming
name: Fang, Chen
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We show that compositions of time-reversal and spatial symmetries, also known as the magnetic-space-group symmetries, protect topological invariants as well as surface states that are distinct from those of all preceding topological states. We obtain, by explicit and exhaustive construction, the topological classification of electronic band insulators that are magnetically ordered for each one of the 1421 magnetic space groups in three dimensions. We have also computed the symmetry-based indicators for each nontrivial class, and, by doing so, establish the complete mapping from symmetry representations to topological invariants.
description: 153 pages, 21 figures
Many-body localization of 1D disordered impenetrable two-component fermions
Creators: name: Bahovadinov, M. S.
name: Kurlov, D. V.
name: Altshuler, B. L.
name: Shlyapnikov, G. V.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: We study effects of disorder on eigenstates of 1D two-component fermions with infinitely strong Hubbard repulsion. We demonstrate that the spin-independent (potential) disorder reduces the problem to the one-particle Anderson localization taking place at arbitrarily weak disorder. In contrast, a random magnetic field can cause reentrant many-body localization-delocalization transitions. Surprisingly weak magnetic field destroys one-particle localization caused by not too strong potential disorder, whereas at much stronger fields the states are many-body localized. We present numerical support of these conclusions.
ISHNE: Influence Self-attention for Heterogeneous Network Embedding
Creators: name: Yan, Yang
name: Wang, Qiuyan
Publisher: name: arXiv
Year: 2021
Subjects: subject: Social and Information Networks (cs.SI)
subject: FOS: Computer and information sciences
subject: I.2.4; I.2.6

description: In recent years, Graph Neural Networks has received enormous attention from academia for its huge potential of modeling the network traits such as macrostructure and single node attributes. However, prior mainstream works mainly focus on homogeneous network and lack the capacity to characterize the network heterogeneous property. Besides, most previous literature cannot model the influence under microscope vision, making it infeasible to model the joint relation between the heterogeneity and mutual interaction within multiple relation type. In this paper, we propose an Influence Self-attention network to address the difficulties mentioned above. To model heterogeneity and mutual interaction, we redesign attention mechanism with influence factor on the single-type relation level, which learns the importance coefficient from its adjacent neighbors under the same meta-path based patterns. To incorporate the heterogeneous meta-path in a unified dimension, we developed a self-attention based framework for meta-path relation fusion according to the learned meta-path coefficient. Our experimental results demonstrate that our framework not only achieve higher results than current state-of-the-art baselines, but also show promising vision on depicting heterogeneous interactive relations under complicated network structure.
Intricate Relations Among Particle Collision, Relative Motion and Clustering in Turbulent Clouds: Computational Observation and Theory
Creators: name: Saw, Ewe-Wei
name: Meng, Xiaohui
Publisher: name: arXiv
Year: 2021
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: Considering turbulent clouds containing small inertial particles, we investigate the effect of particle collision, in particular collision-coagulation, on particle clustering and particle relative motion. We perform direct numerical simulation (DNS) of coagulating particles in isotropic turbulent flow in the regime of small Stokes number ($St=0.001-0.54$) and find that, due to collision-coagulation, the radial distribution functions (RDFs) fall-off dramatically at scales $r \sim d\,\,$ (where $d$ is the particle diameter) to small but finite values, while the mean radial-component of particle relative velocities (MRV) increase sharply in magnitudes. Based on a previously proposed Fokker-Planck (drift-diffusion) framework, we derive a theoretical account of the relationship among particle collision-coagulation rate, RDF and MRV. The theory includes contributions from turbulent-fluctuations absent in earlier mean-field theories. We show numerically that the theory accurately accounts for the DNS results (i.e., given an accurate RDF, the theory could produce an accurate MRV). Separately, we also propose a phenomenological model that could directly predict MRV and find that it is accurate when calibrated using fourth moments of the fluid velocities. We use the model to derive a general solution of RDF. We uncover a paradox: the past empirical success of the differential version of the theory is theoretically unjustified. We see a further shape-preserving reduction of the RDF (and MRV) when the gravitational settling parameter ($S_g$) is of order $O(1)$. Our results demonstrate strong coupling between RDF and MRV and imply that earlier isolated studies on either RDF or MRV have limited relevance for predicting particle collision rate.
Null Dimensional Reduction of M2-Brane
Creators: name: Kluson, J.
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We perform a general reduction of an M2-brane on a space-time that admits a null Killing vector leading to fundamental string and D2-brane action in Newton-Cartan background.
description: 14 pages, reference added
A Riemannian Metric for Geometry-Aware Singularity Avoidance by Articulated Robots
Creators: name: Marić, Filip
name: Petrović, Luka
name: Guberina, Marko
name: Kelly, Jonathan
name: Petrović, Ivan
Publisher: name: arXiv
Year: 2021
Subjects: subject: Robotics (cs.RO)
subject: FOS: Computer and information sciences

description: Articulated robots such as manipulators increasingly must operate in uncertain and dynamic environments where interaction (with human coworkers, for example) is necessary. In these situations, the capacity to quickly adapt to unexpected changes in operational space constraints is essential. At certain points in a manipulator's configuration space, termed singularities, the robot loses one or more degrees of freedom (DoF) and is unable to move in specific operational space directions. The inability to move in arbitrary directions in operational space compromises adaptivity and, potentially, safety. We introduce a geometry-aware singularity index, defined using a Riemannian metric on the manifold of symmetric positive definite matrices, to provide a measure of proximity to singular configurations. We demonstrate that our index avoids some of the failure modes and difficulties inherent to other common indices. Further, we show that this index can be differentiated easily, making it compatible with local optimization approaches used for operational space control. Our experimental results establish that, for reaching and path following tasks, optimization based on our index outperforms a common manipulability maximization technique and ensures singularity-robust motions.
description: 12 pages, 12 figures
Reachable Distance Function for KNN Classification
Creators: name: Zhang, Shichao
name: Li, Jiaye
name: Li, Yangding
Publisher: name: arXiv
Year: 2021
Subjects: subject: Machine Learning (cs.LG)
subject: Artificial Intelligence (cs.AI)
subject: FOS: Computer and information sciences

description: Distance function is a main metrics of measuring the affinity between two data points in machine learning. Extant distance functions often provide unreachable distance values in real applications. This can lead to incorrect measure of the affinity between data points. This paper proposes a reachable distance function for KNN classification. The reachable distance function is not a geometric direct-line distance between two data points. It gives a consideration to the class attribute of a training dataset when measuring the affinity between data points. Concretely speaking, the reachable distance between data points includes their class center distance and real distance. Its shape looks like "Z", and we also call it a Z distance function. In this way, the affinity between data points in the same class is always stronger than that in different classes. Or, the intraclass data points are always closer than those interclass data points. We evaluated the reachable distance with experiments, and demonstrated that the proposed distance function achieved better performance in KNN classification.
MetaLabelNet: Learning to Generate Soft-Labels from Noisy-Labels
Creators: name: Algan, Görkem
name: Ulusoy, Ilkay
Publisher: name: arXiv
Year: 2021
Subjects: subject: Machine Learning (cs.LG)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: Real-world datasets commonly have noisy labels, which negatively affects the performance of deep neural networks (DNNs). In order to address this problem, we propose a label noise robust learning algorithm, in which the base classifier is trained on soft-labels that are produced according to a meta-objective. In each iteration, before conventional training, the meta-objective reshapes the loss function by changing soft-labels, so that resulting gradient updates would lead to model parameters with minimum loss on meta-data. Soft-labels are generated from extracted features of data instances, and the mapping function is learned by a single layer perceptron (SLP) network, which is called MetaLabelNet. Following, base classifier is trained by using these generated soft-labels. These iterations are repeated for each batch of training data. Our algorithm uses a small amount of clean data as meta-data, which can be obtained effortlessly for many cases. We perform extensive experiments on benchmark datasets with both synthetic and real-world noises. Results show that our approach outperforms existing baselines.
Learning Accurate Business Process Simulation Models from Event Logs via Automated Process Discovery and Deep Learning
Creators: name: Camargo, Manuel
name: Dumas, Marlon
name: González-Rojas, Oscar
Publisher: name: arXiv
Year: 2021
Subjects: subject: Artificial Intelligence (cs.AI)
subject: Software Engineering (cs.SE)
subject: FOS: Computer and information sciences

description: Business process simulation is a well-known approach to estimate the impact of changes to a process with respect to time and cost measures -- a practice known as what-if process analysis. The usefulness of such estimations hinges on the accuracy of the underlying simulation model. Data-Driven Simulation (DDS) methods leverage process mining techniques to learn process simulation models from event logs. Empirical studies have shown that, while DDS models adequately capture the observed sequences of activities and their frequencies, they fail to accurately capture the temporal dynamics of real-life processes. In contrast, generative Deep Learning (DL) models are better able to capture such temporal dynamics. The drawback of DL models is that users cannot alter them for what-if analysis due to their black-box nature. This paper presents a hybrid approach to learn process simulation models from event logs wherein a (stochastic) process model is extracted via DDS techniques, and then combined with a DL model to generate timestamped event sequences. An experimental evaluation shows that the resulting hybrid simulation models match the temporal accuracy of pure DL models, while partially retaining the what-if analysis capability of DDS approaches.
description: 16 pages, 4 figures
Minimization of magnetic forces on Stellarator coils
Creators: name: Robin, Rémi
name: Volpe, Francesco
Publisher: name: arXiv
Year: 2021
Subjects: subject: Optimization and Control (math.OC)
subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: Magnetic confinement devices for nuclear fusion can be large and expensive. Compact stellarators are promising candidates for costreduction, but introduce new difficulties: confinement in smaller volumes requires higher magnetic field, which calls for higher coil-currents and ultimately causes higher Laplace forces on the coils-if everything else remains the same. This motivates the inclusion of force reduction in stellarator coil optimization. In the present paper we consider a coil winding surface, we prove that there is a natural and rigorous way to define the Laplace force (despite the magnetic field discontinuity across the current-sheet), we provide examples of cost associated (peak force, surface-integral of the force squared) and discuss easy generalizations to parallel and normal force-components, as these will be subject to different engineering constraints. Such costs can then be easily added to the figure of merit in any multi-objective stellarator coil optimization code. We demonstrate this for a generalization of the REGCOIL code [1], which we rewrote in python, and provide numerical examples for the NCSX (now QUASAR) design. We present results for various definitions of the cost function, including peak force reductions by up to 40 %, and outline future work for further reduction.
Sonnenfleckenzeichnung Nr. 17925.
Zeichnung von Flecken und Fackelflächen zur Ermittlung der Sonnenaktivität am 10.09.1951, erstellt von Helmut Müller
Creators: name: [s.n.]
Publisher: name: [s.n.]
Year: 1951

description: Bleistiftzeichnung mit Tinte und Farbstift überschrieben, erstellt als Projektionsbildzeichnung in der Eidgenössischen Sternwarte Zürich. Instrument: Kern-Merz-Refraktor.
Die Beobachtungen zu Einzelflecken und zu Sonnenfleckengruppen wurden mit Bleistift auf einem Vordruck eingetragen. Unter Umständen sind Angaben zu Protuberanzen vermerkt
Sonnenfleckenzeichnung unnummeriert, einen Zürcher Lückentag ergänzend.
Zeichnung von Flecken und Fackelflächen zur Ermittlung der Sonnenaktivität am 22.10.1951, erstellt vermutlich von Gaston Coutrez oder J. Delange am Observatoire Royal de Belgique in Uccle
Creators: name: [s.n.]
Publisher: name: [s.n.]
Year: 1951

description: Bleistiftzeichnung mit Tinte und Farbstift, erstellt als Zeichnung nach eigener Vorlage in Uccle.
Instrument: Merz-Grubb Refraktor Teleskop (Öffnung 160 mm, f = 2450 mm, projiziertes Sonnenbild D = 25 cm)
Tailoring Heat Dissipation in Ordered Arrays of Dipolar Coupled Magnetic Nanoparticles
Creators: name: Anand, Manish
Publisher: name: arXiv
Year: 2021
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The main aim of the present work is to analyse the effect of dipolar interaction strength $λ$, particle size $D$ and temperature $T$ on the hysteresis mechanism in ordered arrays of magnetic nanoparticles (MNPs) using computer simulations. The anisotropy axes of the MNPs are assumed to have random orientation to mimic the real system. In the absence of thermal fluctuations and dipolar interaction, the hysteresis follows the Stoner and Wohlfarth model irrespective of $D$, as expected. The hysteresis loop area is minimal for particle sizes $D \approx8-16$ nm at $T=300$ K and $λ=0.0$, indicating the dominance of superparamagnetic character. Switching magnetic interaction on is able to move the MNPs from superparamagnetic to a ferromagnetic state even at room temperature; therefore, magnetic interaction of enough strength enhances the hysteresis loop area. Interestingly, the hysteresis loop area is significant and is the same as that of Stoner and Wohlfarth particle even $T=300$ K and negligible dipolar interaction for ferromagnetic MNPs ($D>16$ nm). The coercive field $μ^{}_oH^{}_c$ and blocking temperature $T^{}_B$ also get enhanced with an increase in $λ$ and $D$. The rigorous analysis of the coercive field $μ^{}_oH^{}_c$ vs temperature data also reveals significant deviation from $T^{3/4}$ dependence of $μ^{}_oH^{}_c$ because of dipolar interaction. The amount of heat dissipated $E^{}_H$ and $μ_oH^{}_c$ decrease rapidly with $T$ for $D\approx 8-16$ nm and $λ\leq0.6$. On the other hand, $E^{}_H$ and $μ^{}_oH^{}_c$ depend weakly on $T$ with $D>16$ nm, even in the weak dipolar limit. The present work should provide a better understanding of magnetic hyperthermia to researchers working on this subject. For physicists, it would be interesting to test experimentally the results described in this article.
description: 24 Pages,7 Figures
Sonnenfleckenzeichnung, unnummeriert.
Zeichnung von Flecken und Fackelflächen zur Ermittlung der Sonnenaktivität am 29.12.1951, erstellt von Gaston Coutrez, Observatoire Royal de Belgique in Uccle
Creators: name: [s.n.]
Publisher: name: [s.n.]
Year: 1951

description: Bleistiftzeichnung mit Tinte und Farbstift, erstellt als Zeichnung nach eigener Vorlage in Uccle.
Instrument: Merz-Grubb Refraktor Teleskop (Öffnung 160 mm, f = 2450 mm, projiziertes Sonnenbild D = 25 cm)
A model of interacting Navier-Stokes singularities
Creators: name: Faller, H.
name: Fery, L.
name: Geneste, D.
name: Dubrulle, B.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: Classical Physics (physics.class-ph)
subject: FOS: Physical sciences

description: We introduce a model of interacting singularities of Navier-Stokes, named pin\,cons. They follow a Hamiltonian dynamics, obtained by the condition that the velocity field around these singularities obeys locally Navier-Stokes equations. This model can be seen of a generalization of the vorton model of Novikov, that was derived for the Euler equations. When immersed in a regular field, the pin\,cons are further transported and sheared by the regular field, while applying a stress onto the regular field, that becomes dominant at a scale that is smaller than the Kolmogorov length. We apply this model to compute the motion of a dipole of pin\,cons. When the initial relative orientation of the dipole is inside the interval (0, pi/2), a dipole made of pin\,con of same intensity exhibits a transient collapse stage, following a scaling with dipole radius tending to 0 like (tc - t) power 0.63. For long time, the dynamics of the dipole is however repulsive, with both components running away from each other to infinity.
description: 24 pages 13 figures
A topological perspective on weather regimes
Creators: name: Strommen, Kristian
name: Chantry, Matthew
name: Dorrington, Joshua
name: Otter, Nina
Publisher: name: arXiv
Year: 2021
Subjects: subject: Atmospheric and Oceanic Physics (physics.ao-ph)
subject: Algebraic Topology (math.AT)
subject: Chaotic Dynamics (nlin.CD)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: It has long been suggested that the mid-latitude atmospheric circulation possesses what has come to be known as `weather regimes', loosely categorised as regions of phase space with above-average density and/or extended persistence. Their existence and behaviour has been extensively studied in meteorology and climate science, due to their potential for drastically simplifying the complex and chaotic mid-latitude dynamics. Several well-known, simple non-linear dynamical systems have been used as toy-models of the atmosphere in order to understand and exemplify such regime behaviour. Nevertheless, no agreed-upon and clear-cut definition of a `regime' exists in the literature. We argue here for an approach which equates the existence of regimes in a dynamical system with the existence of non-trivial topological structure of the system's attractor. We show using persistent homology, an algorithmic tool in topological data analysis, that this approach is computationally tractable, practically informative, and identifies the relevant regime structure across a range of examples.
description: Major revisions and improvements to exposition. More mathematical details in the Appendix. New title
Sonnenfleckenzeichnung, unnummeriert.
Zeichnung von Flecken und Fackelflächen zur Ermittlung der Sonnenaktivität am 13.11.1951, erstellt von Gaston Coutrez, Observatoire Royal de Belgique in Uccle
Creators: name: [s.n.]
Publisher: name: [s.n.]
Year: 1951

description: Bleistiftzeichnung mit Tinte und Farbstift, erstellt als Zeichnung nach eigener Vorlage in Uccle.
Instrument: Merz-Grubb Refraktor Teleskop (Öffnung 160 mm, f = 2450 mm, projiziertes Sonnenbild D = 25 cm)
Sonnenfleckenzeichnung Nr. 17915.
Zeichnung von Flecken und Fackelflächen zur Ermittlung der Sonnenaktivität am 31.08.1951, erstellt von Helmut Müller
Creators: name: [s.n.]
Publisher: name: [s.n.]
Year: 1951

description: Bleistiftzeichnung mit Tinte und Farbstift überschrieben, erstellt als Projektionsbildzeichnung in der Eidgenössischen Sternwarte Zürich. Instrument: Kern-Merz-Refraktor.
Die Beobachtungen zu Einzelflecken und zu Sonnenfleckengruppen wurden mit Bleistift auf einem Vordruck eingetragen. Unter Umständen sind Angaben zu Protuberanzen vermerkt
Sonnenfleckenzeichnung Nr. 17952.
Zeichnung von Flecken und Fackelflächen zur Ermittlung der Sonnenaktivität am 15.10.1951, erstellt von Helmut Müller
Creators: name: [s.n.]
Publisher: name: [s.n.]
Year: 1951

description: Bleistiftzeichnung mit Tinte und Farbstift überschrieben, erstellt als Projektionsbildzeichnung in der Eidgenössischen Sternwarte Zürich. Instrument: Kern-Merz-Refraktor.
Die Beobachtungen zu Einzelflecken und zu Sonnenfleckengruppen wurden mit Bleistift auf einem Vordruck eingetragen. Später wurden ergänzende Angaben aufgrund auswärtiger Beobachtungen direkt auf der Fleckenzeichnung hinzugefügt. Unter Umständen sind Angaben zu Protuberanzen vermerkt
Nomia longicornis
Creators: name: Smith, F.
Publisher: name: Zenodo
Year: 1859
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Halictidae
Nomia
Nomia longicornis

description: 2. Nomia longicornis.
N. nigra, lucida et delicatula punctata, facie pube brevi grisea tecta, femorum posticorum flocco pallido, tibiis externe fusco-pubeseentibus; maris antennis, capite thoraceque longioribus.
Male. Length 4 lines. Brassy, with tints of green on the clypeus, metathorax, and thorax beneath; the head and thorax very closely and finely punctured; the clypeus produced and highly polished; the mandibles rufo-testaceous, the antennae as long as the head and thorax. Thorax: the wings hyaline and splendidly iridescent, the tegulae and the tarsi rufo-testaceous. Abdomen closely punctured, the apical margins of the segments smooth and shining; the head and thorax above with a pale fulvous pubescence, that on the sides of the metathorax and legs pale and glittering; the abdomen has a pale scattered glittering pubescence.
Hab. Aru.
description: Published as part of Smith, F., 1859, Catalogue of hymenopterous insects collected by Mr. A. R. Wallace at the Islands of Aru and Key., pp. 132-158 in Journal of the Proceedings of the Linnean Society of London, Zoology 3 on page 133
On the stationary solutions of random polymer models and their zero-temperature limits
Creators: name: Croydon, David A.
name: Sasada, Makiko
Publisher: name: arXiv
Year: 2021
Subjects: subject: Probability (math.PR)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 82D60 (primary), 37K60, 37L40, 60E05, 60K35, 82B23

description: We derive stationary measures for certain zero-temperature random polymer models, which we believe are new in the case of the zero-temperature limit of the beta random polymer (that has been called the river delta model). To do this, we apply techniques developed for understanding the stationary measures of the corresponding positive-temperature random polymer models (and some deterministic integrable systems). More specifically, the article starts with a survey of results for the four basic beta-gamma models (i.e. the inverse-gamma, gamma, inverse-beta and beta random polymers), highlighting how the maps underlying the systems in question can each be reduced to one of two basic bijections, and that through an `independence preservation' property, these bijections characterise the associated stationary measures. We then derive similar descriptions for the corresponding zero-temperature maps, whereby each is written in terms of one of two bijections. One issue with this picture is that, unlike in the positive-temperature case, the change of variables required is degenerate in general, and so whilst the argument yields stationary solutions, it does not provide a complete characterisation of them. On the other hand, this degeneracy does allow us to explain the appearance of atoms in the stationary measures of certain zero-temperature models. We also derive from our viewpoint various links between random polymer models, some of which recover known results, some of which are novel, and some of which lead to further questions.
Sonnenfleckenzeichnung Nr. 17999.
Zeichnung von Flecken und Fackelflächen zur Ermittlung der Sonnenaktivität am 13.12.1951, erstellt von Helmut Müller
Creators: name: [s.n.]
Publisher: name: [s.n.]
Year: 1951

description: Bleistiftzeichnung mit Tinte und Farbstift überschrieben, erstellt als Projektionsbildzeichnung in der Eidgenössischen Sternwarte Zürich. Instrument: Kern-Merz-Refraktor.
Die Beobachtungen zu Einzelflecken und zu Sonnenfleckengruppen wurden mit Bleistift auf einem Vordruck eingetragen. Unter Umständen sind Angaben zu Protuberanzen vermerkt
Sonnenfleckenzeichnung Nr. 17907.
Zeichnung von Flecken und Fackelflächen zur Ermittlung der Sonnenaktivität am 23.08.1951, erstellt von Helmut Müller
Creators: name: [s.n.]
Publisher: name: [s.n.]
Year: 1951

description: Bleistiftzeichnung mit Tinte und Farbstift überschrieben, erstellt als Projektionsbildzeichnung in der Eidgenössischen Sternwarte Zürich. Instrument: Kern-Merz-Refraktor.
Die Beobachtungen zu Einzelflecken und zu Sonnenfleckengruppen wurden mit Bleistift auf einem Vordruck eingetragen. Später wurden ergänzende Angaben aufgrund auswärtiger Beobachtungen direkt auf der Fleckenzeichnung hinzugefügt. Unter Umständen sind Angaben zu Protuberanzen vermerkt
Comments on Symmetric Mass Generation in 2d and 4d
Creators: name: Tong, David
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Symmetric mass generation is the name given to a mechanism for gapping fermions while preserving a chiral, but necessarily non-anomalous, symmetry. In this paper we describe how symmetric mass generation for continuous symmetries can be achieved using gauge dynamics in two and four dimensions. Various strong coupling effects are invoked, including known properties of supersymmetric gauge theories, specifically the phenomenon of s-confinement, and conjectured properties of non-supersymmetric chiral gauge theories.
description: 24 pages. v2 and v3: typos corrected
Sonnenfleckenzeichnung Nr. 17951.
Zeichnung von Flecken und Fackelflächen zur Ermittlung der Sonnenaktivität am 14.10.1951, erstellt von Helmut Müller
Creators: name: [s.n.]
Publisher: name: [s.n.]
Year: 1951

description: Bleistiftzeichnung mit Tinte und Farbstift überschrieben, erstellt als Projektionsbildzeichnung in der Eidgenössischen Sternwarte Zürich. Instrument: Kern-Merz-Refraktor.
Die Beobachtungen zu Einzelflecken und zu Sonnenfleckengruppen wurden mit Bleistift auf einem Vordruck eingetragen. Unter Umständen sind Angaben zu Protuberanzen vermerkt