cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Generalized Neighbor-Interaction Models Induced by Nonlinear Lattices
Creators: name: Abdullaev, F. Kh.
name: Bludov, Yu. V.
name: Dmitriev, S. V.
name: Kevrekidis, P. G.
name: Konotop, V. V.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: It is shown that the tight-binding approximation of the nonlinear Schrödinger equation with a periodic linear potential and periodic in space nonlinearity coefficient gives rise to a number of nonlinear lattices with complex, both linear and nonlinear, neighbor interactions. The obtained lattices present non-standard possibilities, among which we mention a quasi-linear regime, where the pulse dynamics obeys essentially the linear Schr{ö}dinger equation. We analyze the properties of such models both in connection with their modulational stability, as well as in regard to the existence and stability of their localized solitary wave solutions.
Helical Fluid and (Hall)-MHD Turbulence: a Brief Review
Creators: name: Pouquet, Annick
name: Yokoi, Nobumitsu
Publisher: name: arXiv
Year: 2021
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: Helicity, a measure of the breakage of reflectional symmetry representing the topology of turbulent flows, contributes in a crucial way to their dynamics and to their fundamental statistical properties. We review several of their main features, both new and old, as the discovery of bi-directional cascades or the role of helical vortices in the enhancement of large-scale magnetic fields in the dynamo problem. The dynamical contribution in magnetohydrodynamic (MHD) of the cross-correlation between velocity and induction is discussed as well. We consider next how turbulent transport is affected by helical constraints, in particular in the context of magnetic reconnection and fusion plasmas {under one- and two-fluid approximations}. Central issues on how to construct turbulence models for non-reflectionally symmetric helical flows are reviewed, including in the presence of shear, and we finally briefly mention the possible role of helicity in the development of strongly localized quasi-singular structures {at small scale).
description: 14 pages, 0 figure 0 table
Aspects of the disordered harmonic chain
Creators: name: Fogedby, Hans C.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We discuss the driven harmonic chain with fixed boundary conditions subject to weak coupling strength disorder. We discuss the evaluation of the Liapunov exponent in some detail expanding on the dynamical system theory approach by Levi et al. We show that including mass disorder the mass and coupling strength disorder can be combined in a renormalised mass disorder. We review the method of Dhar regarding the disorder-averaged heat current, apply the approach to the disorder-averaged large deviation function and finally comment on the validity of the Gallavotti-Cohen fluctuation theorem. The paper is also intended as an introduction to the field and includes detailed calculations.
description: 22 pages, 7 figures, latex document
Structured input-output analysis of transitional wall-bounded flows
Creators: name: Liu, Chang
name: Gayme, Dennice F.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: Systems and Control (eess.SY)
subject: FOS: Physical sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: Input-output analysis of transitional channel flows has proven to be a valuable analytical tool for identifying important flow structures and energetic motions. The traditional approach abstracts the nonlinear terms as forcing that is unstructured, in the sense that this forcing is not directly tied to the underlying nonlinearity in the dynamics. This paper instead employs a structured singular value-based approach that preserves certain input-output properties of the nonlinear forcing function in an effort to recover the larger range of key flow features identified through nonlinear analysis, experiments, and direct numerical simulation (DNS) of transitional channel flows. Application of this method to transitional plane Couette and plane Poiseuille flows leads to not only the identification of the streamwise coherent structures predicted through traditional input-output approaches, but also the characterization of the oblique flow structures as those requiring the least energy to induce transition in agreement with DNS studies, and nonlinear optimal perturbation analysis. The proposed approach also captures the recently observed oblique turbulent bands that have been linked to transition in experiments and DNS with very large channel size. The ability to identify the larger amplification of the streamwise varying structures predicted from DNS and nonlinear analysis in both flow regimes suggests that the structured approach allows one to maintain the nonlinear effects associated with weakening of the lift-up mechanism, which is known to dominate the linear operator. Capturing this key nonlinear effect enables the prediction of the wider range of known transitional flow structures within the analytical input-output modeling paradigm.
description: 26pages, 10 figures
การศึกษาโครงสร้างความร่วมมือในการจัดการก่อนการเป็นเมืองมรดกโลกกรณีศึกษา เชียงใหม่ ประเทศไทย
Creators: name: ปิยเดช อัครโพธิวงศ์
Publisher: name: Thammasat University
Year: 2019
Subjects: แนวคิดการอนุรักษ์มรดกมีชีวิต
การอนุรักษ์
การวิเคราะห์โครงข่ายทางสังคม
มรดกโลก
เชียงใหม่

description: Journal of Architectural/Planning Research and Studies, 16, 1, 125-138
Time for pulse traversal through slabs of dispersive and negative ($ε$, $μ$) materials
Creators: name: Nanda, Lipsa
name: Ramakrishna, S. Anantha
Publisher: name: arXiv
Year: 2007
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Other Condensed Matter (cond-mat.other)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: The traversal times for an electromagnetic pulse traversing a slab of dispersive and dissipative material with negative dielectric permittivity ($ε$) and magnetic permeability ($μ$) have been calculated by using the average flow of electromagnetic energy in the medium. The effects of bandwidth of the pulse and dissipation in the medium have been investigated. While both large bandwidth and large dissipation have similar effects in smoothening out the resonant features that appear due to Fabry-Pérot resonances, large dissipation can result in very small or even negative traversal times near the resonant frequencies. We have also investigated the traversal times and Wigner delay times for obliquely incident pulses and evanescent pulses. The coupling to slab plasmon polariton modes in frequency ranges with negative $ε$ or $μ$ is shown to result in large traversal times at the resonant conditions. We also find that the group velocity mainly contributes to the delay times for pulse propagating across a slab with n=-1. We have checked that the traversal times are positive and subluminal for pulses with sufficiently large bandwidths.
description: 9 pages, 9 figures, Submitted to Phys. Rev. A
Development of a black galingale dryer using biomass working together with a CLOHP/ CV heat exchanger
Creators: name: Pattanapol Meena
Publisher: name: Mahasarakham University
Year: 2014
Subjects: Closed-loop oscillating heat pipe (CLOHP), check valve (CV), heat exchanger, drying, biomass

description: 2, 33, Journal of SCIENCE and TECHNOLOGY Mahasarakham University
A comprehensive study of 2019-2020 flare of OJ 287 using AstroSat, Swift, and NuSTAR
Creators: name: Prince, Raj
name: Raman, Gayathri
name: Khatoon, Rukaiya
name: Agarwal, Aditi
name: Varun
name: Gupta, Nayantara
name: Czerny, Bożena
name: Majumdar, Pratik
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: OJ 287 is a well-studied binary black hole system, that occasionally exhibits bright X-ray and optical flares. Here we present a detailed spectral study of its second brightest X-ray flare observed during 2019-2020 using archival Swift and NuSTAR observations along with ToO observations from AstroSat. The entire flaring period is divided into three states, defined as low, intermediate, and high states. The variation of hardness ratio (HR) with 0.3-10.0 keV integrated flux suggests a \enquote{softer-when-brighter} behavior, as also previously reported based on flux-index variations. Simultaneous high state X-ray spectra obtained using Swift, NuSTAR and AstroSat are very steep with a power-law index $>$2. A significant spectral change is observed in AstroSat-SXT and LAXPC spectrum which is consistent with Swift-XRT and NuSTAR spectrum. Together, optical-UV and X-ray spectrum during the high flux state, suggesting the emergence of a new high BL Lacertae (HBL) component. We have modeled the synchrotron peak with publicly available code named GAMERA for low, intermediate, and high flux state. Our modeling suggests the need of high magnetic field to explain the high state under the leptonic scenarios. Increase in the magnetic field value inside the jet could be linked to the increase in accretion rate as expected in the BH-disk impact scenario. The color-magnitude diagram reveals a \enquote{bluer-when-brighter} spectral energy distribution chromatism during the flaring period. Different chromatism or no chromatism at various occasions suggests a complex origin of optical emission, which is believed to be produced by disc impact or through synchrotron emission in the jet.
description: 14 pages, 13 figures, 3 tables, Accepted in MNRAS
An English translation o Bertrand's theorem
Creators: name: Santos, F. C.
name: Soares, V.
name: Tort, A. C.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Classical Physics (physics.class-ph)
subject: Physics Education (physics.ed-ph)
subject: FOS: Physical sciences

description: A beautiful theorem due to J. L. F. Bertrand concerning the laws of attraction that admit bounded closed orbits for arbitrarily chosen initial conditions is translated from French into English.
description: This is English version of a beautiful theorem due to Joseph Bertrand; simple latex file, no figures, six pages
Broadband study of BL Lac during flare of 2020: Spectral evolution and emergence of HBL component
Creators: name: Prince, Raj
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: BL Lacertae (BL Lac) is categorized as TeV blazar and considered as a possible source of astrophysical neutrinos. In 2020, the brightest X-ray flare ever detected from it. A detailed study can answer many puzzling questions related to multiband emissions and fast-flux variability often seen in this kind of source. We have performed the temporal and spectral analysis of the brightest flare. The variability is characterized by the fractional variability amplitude and the variability time. We found that the source has crossed all its previous limits of flux and reached the maximum ever seen from it in optical and X-rays. It is highly variable in X-rays with fractional variability above 100$\%$ (1.8397$\pm$0.0181) and the fastest variability time of 11.28 hours within a day. The broadband light curves correlation with X-ray suggest a time lag of one day. A broadband SED modeling is pursued to understand the possible physical mechanisms responsible for broadband emission. Modeling requires two emission regions located at two different sites to explain the low and high flux states. A significant spectral change is observed in the optical-UV and X-ray spectrum during the high state, which eventually leads to shifts in the location of the synchrotron peak towards higher energy, suggesting an emergence of a new HBL component.
description: 13 pages, 11 figures, 3 tables, Accepted in MNRAS
Interplay between polarization and quantum correlations of confined polaritons
Creators: name: Bleu, Olivier
name: Levinsen, Jesper
name: Parish, Meera M.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Optics (physics.optics)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We investigate polariton quantum correlations in a coherently driven box cavity in the low driving regime, with a particular focus on accounting for the polarization degree of freedom. The possibility of having different interaction strengths between co- and cross-circularly polarized polaritons as well as a realistic linear-polarization splitting allows one to model the system as two coupled nonlinear resonators with both self- and cross-Kerr-like nonlinearities, thus making our results potentially relevant for other experimental platforms. Within an effective wave-function approach, we obtain analytical expressions for the steady-state polarization-resolved polariton populations and second-order correlation functions, which agree very well with our numerical results obtained from a Lindblad master equation. Notably, we highlight that depending on the excitation polarization (circular or linear), both the unconventional (interference-mediated) and conventional (mediated by nonlinearities) antibunchings can be investigated in a single cavity. Moreover, using our results, we argue that recent experiments on confined fiber-cavity polaritons are likely to have probed a regime where the dominant interaction is between cross-polarized polaritons, which is characteristic of the polariton Feshbach resonance. We furthermore investigate the regime close to resonance using a two-channel model, and we show that systems with large biexciton binding energies, such as atomically thin semiconductors, are promising platforms for realizing strong polariton antibunching.
description: 24 pages, 12 figures
Βελτιστοποίηση συστημάτων ελέγχου ανεμογεννητριών για την αύξηση της ενεργειακής απόδοσής τους:
Creators: name: Μεσεμανώλης, Αθανάσιος Ι.
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Ανανεώσιμες πηγές ενέργειας
Ηλεκτρικές μηχανές
Ηλεκτρονικά Ισχύος
Συστήματα ελέγχου
Wind Energy Conversion Systems
Power electronics
Electric Machines
Control Systems

description: Σκοπός της διατριβής ήταν η ανάπτυξη μιας μεθόδου ελέγχου για αιολικά συστήματα, η οποία θα επιτυγχάνει μεγιστοποίηση της παρεχόμενης ισχύος προς το ηλεκτρικό δίκτυο. Το σύστημα ελέγχου που αναπτύχθηκε επιτυγχάνει λειτουργία του ανεμοκινητήρα στην ταχύτητα μέγιστης ισχύος και παράλληλα μειώνει τις απώλειες της ηλεκτρογεννήτριας, ούτως ώστε να μεγιστοποιείται η παραγόμενη ισχύς. Ταυτόχρονα, αναπτύχθηκε μια μέθοδος ευθυγράμμισης της ατράκτου της ανεμογεννήτριας με την διεύθυνση του ανέμου, η οποία επιτυγχάνει γρήγορο και ακριβή εντοπισμό της διεύθυνσης του ανέμου. Η λειτουργία του συστήματος ελέγχθηκε τόσο σε επίπεδο προσομοίωσης όσο και σε πειραματικό αιολικό σύστημα.
description: Aim of the thesis was the introduction of a control method for wind energy conversion system which achieve maximum power production to the utility grid. The proposed control system achieves operation at the maximum power point of the wind turbine and it simultaneously reduces the electrical generator losses, such as power production is maximized. Moreover, a method for the alignment of the nacelle of the wind turbine with the direction of the incident wind has been developed, that achieve fast and accurate tracking of the wind direction. The operation of the control system has been validated through simulations and on experimental wind energy conversion system installations.
MPEC 2024-T51 : 2024 TJ
Creators: name: Minor Planet Center Staff
Publisher: name: The Minor Planet Center
Year: 2024
Subjects: subject: Small Solar System bodies
valueUri: http://astrothesaurus.org/uat/1469
subject: 2024 TJ

description: The Minor Planet Electronic Circulars contain information on unusual minor planets, routine data on comets and natural satellites, and occasional editorial announcements.  They are published on behalf of Division F of the International Astronomical Union by the Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Strategies for collecting Metrics and Logs in WebAPI using Csharp with OpenTelemetry
Creators: name: Filho, Nagib
Publisher: name: Zenodo
Year: 2024
Subjects: Strategies
Metrics Collection
Logs
C# Systems
OpenTelemetry
Monitoring
Observability
Instrumentation
Telemetry
Performance Analysis
Error Diagnosis
Integration

description: The article provides an introduction to OpenTelemetry, an essential tool for the observability of distributed systems. With the increasing complexity of applications, OpenTelemetry offers a unified standard for collecting metrics, logs, and tracing. The text details the initial setup in C# applications, including the collection of metrics and logs, integration with monitoring backends like Jaeger, and best practices for instrumentation.
Η οργάνωση της παραγωγής και η λειτουργία της κεραμικής των οικιστικών οριζόντων Ι – ΙΙΙ από το Αρχοντικό Γιαννιτσών:
Creators: name: Δελιόπουλος, Γεώργιος Κ.
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Κεραμική παράδοση
Τυπολογία
Συγκειμενική ανάλυση
Εποχή Χαλκού
Pottery tradition
Typology
Contextual analysis
Bronze Age

description: Ο σκοπός της παρούσας διατριβής είναι να παρουσιαστούν τα βασικά τεχνολογικά και μορφολογικά χαρακτηριστικά της κεραμικής των οικιστικών οριζόντων IIΙ-ΙΙ (Πρώιμη/ Μέση Εποχή Χαλκού) και του ορίζοντα Ι (Ύστερη Εποχή Χαλκού) από το Αρχοντικό Γιαννιτσών, ώστε να μελετηθούν η οργάνωση της κεραμικής παραγωγής και η λειτουργία των αγγείων στους παραπάνω οικιστικούς ορίζοντες. Η μελέτη βασίστηκε σε θεωρητικές έννοιες, όπως είναι τα δρώντα υποκείμενα (agents), η δομοποίηση (structuration), η βιογραφία των αντικειμένων, η ακολουθία εγχειρημάτων και η συγκειμενική ανάλυση. Τα αποτελέσματα της μελέτης δείχνουν ότι η κεραμική παράδοση του Αρχοντικού σε όλους τους οικιστικούς ορίζοντες εντάσσεται στην ευρύτερη, κοινή κεραμική παράδοση σύγχρονων οικισμών της κεντρικής και δυτικής Μακεδονίας. Επιπλέον, η κεραμική παραγωγή φαίνεται ότι ήταν μη εντατικοποιημένη και μικρής κλίμακας, από εξειδικευμένους αγγειοπλάστες του οικισμού, οι οποίοι ακολουθούσαν γενικούς κατασκευαστικούς κανόνες. Ωστόσο, η χρήση και ο ρόλος ορισμένων κεραμικών κατηγοριών διαφέρουν ανάμεσα στους ορίζοντες της ΠΕΧ/ΜΕΧ και στον ορίζοντα της ΥΕΧ.
description: The present thesis aims to present the technological and morphological traits of pottery from the habitation layers III-ΙΙ (Early/ Middle Bronze Age) and the layer I (Late Bronze Age) of Archontiko Giannitson, in order to examine the organization of pottery production and the function of vessels in the aforementioned layers. The study followed some theoretical concepts, such as agency, structuration, object biography, chaine opératoire and contextual analysis. The results of pottery study indicate that pottery tradition of Bronze Age Archontiko belongs to a common pottery tradition in most contemporary, central and western Macedonian sites. Furthermore, pottery production in Archontiko was organized on a small scale by specialized potters, who followed some fixed manufacture rules. However, the use and the role of some pottery categories changed from EBA/MBA layers to the LBA layer.
Radiation-cooled Dew Water Condensers Studied by Computational Fluid Dynamic (CFD)
Creators: name: Clus, O.
name: Ouazzani, Jalil
name: Muselli, M.
name: Nikolayev, Vadim
name: Sharan, Girja
name: Beysens, D.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: Harvesting condensed atmospheric vapour as dew water can be an alternative or complementary potable water resource in specific arid or insular areas. Such radiation-cooled condensing devices use already existing flat surfaces (roofs) or innovative structures with more complex shapes to enhance the dew yield. The Computational Fluid Dynamic - CFD - software PHOENICS has been programmed and applied to such radiation cooled condensers. For this purpose, the sky radiation is previously integrated and averaged for each structure. The radiative balance is then included in the CFD simulation tool to compare the efficiency of the different structures under various meteorological parameters, for complex or simple shapes and at various scales. It has been used to precise different structures before construction. (1) a 7.32 m^2 funnel shape was studied; a 30 degree tilted angle (60 degree cone half-angle) was computed to be the best compromise for funnel cooling. Compared to a 1 m^2 flat condenser, the cooling efficiency was expected to be improved by 40%. Seventeen months measurements in outdoor tests presented a 138 % increased dew yield as compared to the 1 m^2 flat condenser. (2) The simulation results for 5 various condenser shapes were also compared with experimental measurement on corresponding pilots systems: 0.16 m^2 flat planar condenser, 1 m^2 and 30 degree tilted planar condenser, 30 m^2 and 30 degree tilted planar condenser, 255 m^2 multi ridges, a preliminary construction of a large scale dew plant being implemented in the Kutch area (Gujarat, India).
Nonlinear Hall Effects
Creators: name: Du, Z. Z.
name: Lu, Hai-Zhou
name: Xie, X. C.
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: The Hall effects comprise one of the oldest but most vital fields in condensed matter physics, and they persistently inspire new findings, such as quantum Hall effects and topological phases of matter. The recently discovered nonlinear Hall effect is a new member of the family of Hall effects. It is characterized as a transverse Hall voltage in response to two longitudinal currents in the Hall measurement, but it does not require time-reversal symmetry to be broken. It has deep connections to symmetry and topology and, thus, opens new avenues by which to probe the spectral, symmetry and topological properties of emergent quantum materials and phases of matter. In this Perspective, we present an overview of the recent progress regarding the nonlinear Hall effect. We discuss the open problems, the prospects of the use of the nonlinear Hall effect in spectroscopic and device applications, and generalizations to other nonlinear transport effects.
description: A subscription-free version can be found at https://rdcu.be/cwqYd
The Quantum Configuration Space of Loop Quantum Cosmology
Creators: name: Velhinho, J. M.
Publisher: name: arXiv
Year: 2007
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: The article gives an account of several aspects of the space known as the Bohr compactification of the line, featuring as the quantum configuration space in loop quantum cosmology, as well as of the corresponding configuration space realization of the so-called polymer representation. Analogies with loop quantum gravity are explored, providing an introduction to (part of) the mathematical structure of loop quantum gravity, in a technically simpler context.
description: 14 pages. Minor changes, typos corrected, 1 reference added. To appear in Class. Quantum Grav
Desenvolvimento de um chatbot para atendimento automático em pizzarias
Creators: name: Douglas Rodrigues de Sousa
Publisher: name: Zenodo
Year: 2021
Subjects: Chatbot
Processamento de Linguagem Natural
Reconhecimento de Padrões
Telegram
Atendimento ao Cliente
Inteligência Artificial
Pizza
Automação de Atendimento
Natural Language Processing (NLP)
Python
scikit-learn
Naïve Bayes
spacy

description: This work deals with developing a chatbot aimed at serving pizza shop customers using Naturallanguage processing tools and pattern recognition, aimed at the Telegram platform. The mainidea is to build a chatbot to deal with overload problem from calls. Most of the time, theservice is done only by one employee by telephone or message exchange applications, such asWhatsapp, Telegram, and Facebook Messenger. In this way, customers end up waiting a longtime to be served because they depend on the establishment’s ability to deal with inquiries. Theproject implements pattern recognition techniques for the processing and classifying messages,thus assisting pizzerias in attending and questions related to customer queries. Finally, thiswork presents the results obtained by implementing and future works. The project results wereconsidered satisfactory, given that most of the questions asked to the system were answeredcorrectly.

 

Este trabalho trata do desenvolvimento de um chatbot destinado ao atendimento de clientes depizzarias utilizando ferramentas de processamento de Linguagem Natural e reconhecimentode padrões, voltados à plataforma Telegram. A ideia do chatbot é solucionar o problema desobrecarga de atendimentos, pois na maioria das vezes o atendimento é feito somente por umfuncionário por meio telefônico ou aplicativos de trocas de mensagens, tais como Whatsapp,Telegram, Facebook Messenger, entre outros. Dessa maneira, os clientes esperam muito tempopara serem atendidos, pois dependem da capacidade do estabelecimento de lidar com as solicitações. O projeto implementa técnicas de reconhecimento de padrões para o processamentoe classificação das mensagens, visando assim auxiliar pizzarias nos atendimentos e questõesreferentes a dúvidas dos clientes. Os resultados do projeto foram considerados satisfatórios hajavista que a maioria das perguntas feitas ao sistema foram respondidas de forma correta.

 

Palavras Chave: Atendimento de clientes. Chatbot. Processamento de Linguagem Natural.Naïve Bayes. spaCe. Telegram.
Instantons and Berry's connections on quantum graph
Creators: name: Inoue, Tomonori
name: Sakamoto, Makoto
name: Ueba, Inori
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: In this paper, we study non-Abelian Berry's connections in the parameter space of boundary conditions for Dirac zero modes on quantum graphs. We apply the ADHM construction, which is the method for constructing Yang-Mills instanton solutions, to the Berry's connections. Then we find that the instanton configurations appear as the Berry's connections.
description: 18 pages, 3figures
Analysis of Lundgren's matched asymptotic expansion approach to the Kármán-Howarth equation using the EDQNM turbulence closure
Creators: name: Meldi, Marcello
name: Vassilicos, John Christos
Publisher: name: arXiv
Year: 2021
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: In this paper we investigate whether the features of the non-equilibrium cascade, which have been identified in recent studies using high-fidelity tools, can be captured in the case of the classical dissipation scaling by turbulence closures based on the statistical description of freely decaying isotropic turbulence. Numerical results obtained using the EDQNM model over a very large range of Reynolds numbers (from $Re_λ=50$ up to $Re_λ=10^6$) are analyzed to perform an extensive investigation of the scaling region identified as inertial range in Kolmogorov's theory. It is observed that EDQNM results are in agreement with the results of Lundgren's matched asymptotic expansion approach to the Karman-Howarth equation. Both predict that the Kolmogorov inertial range equilibrium is never obtained irrespective of Reynolds number. Equilibrium is reached in the vicinity of the Taylor length $λ$ (which depends on viscosity) as Reynolds number tends to infinity and there is a gradual departure from equilibrium as the length scale moves away from $λ$, in particular towards scales larger than $λ$ all the way to the integral length-scale.
Deterministic quantum one-time pad via Fibonacci anyons
Creators: name: Xu, Cheng-Qian
name: Zhou, D. L.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Anyonic states, which are topologically robust originated from their peculiar structure of Hilbert space, have important applications in quantum computing and quantum communication. When an anyonic state is used as an information carrier of the deterministic quantum one-time pad (DQOTP), we find that the Fibonacci particle-antiparticle pair produced from vacuum can be used to asymptotically send $2\log_2 d_τ$ bits of classical information ($d_τ$ is the quantum dimension of a Fibonacci anyon $τ$), which equals to the anyonic mutual information of the pair. Furthermore, by studying the DQOTP via a parameterized state of six Fibonacci anyons with trivial total charge, we give the analytical results of the maximum number of messages that can be sent for different parameters, which is a step function with every step corresponding to a regular simplex from the viewpoint of geometry. The results for the maximum number of messages sent by the DQOTP can be explained by the anyonic accessible information.
description: 8 pages, 3 figures
Universal statistics of waves in a random time-varying medium
Creators: name: Carminati, R.
name: Chen, H.
name: Pierrat, R.
name: Shapiro, B.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: We study the propagation of waves in a medium in which the wave velocity fluctuates randomly in time. We prove that at long times, the statistical distribution of the wave energy is log-normal, with the average energy growing exponentially. For weak disorder, another regime preexists at shorter times, in which the energy follows a negative exponential distribution, with an average value growing linearly with time. The theory is in perfect agreement with numerical simulations, and applies to different kinds of waves. The existence of such universal statistics bridges the fields of wave propagation in time-disordered and space-disordered media.
Conifold singularities, resumming instantons and non-perturbative mirror symmetry
Creators: name: Saueressig, Frank
name: Vandoren, Stefan
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We determine the instanton corrected hypermultiplet moduli space in type IIB compactifications near a Calabi-Yau conifold point where the size of a two-cycle shrinks to zero. We show that D1-instantons resolve the conifold singularity caused by worldsheet instantons. Furthermore, by resumming the instanton series, we reproduce exactly the results obtained by Ooguri and Vafa on the type IIA side, where membrane instantons correct the hypermultiplet moduli space. Our calculations therefore establish that mirror symmetry holds non-perturbatively in the string coupling.
description: 14 pages, 1 figure
Towards understanding how Touch ID impacts users' authentication secrets selection for iPhone lock.
Creators: name: Cherapau, Ivan
Publisher: name: Zenodo
Year: 2015
Subjects: Smartphone
Security
iPhone
Touch ID
Authentication

description: Smartphones today store large amounts of data that can be confidential, private or sensitive. To protect such data, all mobile OSs have a phone lock mechanism, a mechanism that requires user authentication in order to access applications or data on the phone, while also allowing to keep data-at-rest encrypted with encryption key dependent on the authentication secret. Recently Apple has introduced Touch ID feature that allows to use a fingerprint-based authentication to unlock an iPhone. The intuition behind such technology was that its usability would motivate users to use stronger passwords for locking their devices without sacrificing usability substantially. To this date, it is not clear, however, if users take an advantage of Touch ID technology and if they, indeed, employ stronger authentication secrets. It is the main objective and the contribution of this work to fill this knowledge gap. In order to answer this question, we conducted three user studies (a) an in-person survey with 90 subjects, (b) an interview study with 21 participants, and (c) an online survey with 374 subjects. Overall we found that users do not take an advantage of Touch ID and use weak authentication secrets, mainly PIN-codes, similarly to those users who do not have Touch ID sensor on their devices. To our surprise, we found that more than 30% of subjects in each group did not know that they could use alphanumeric passwords instead of four digits PIN-codes. Others stated that they adopted PIN-codes due to better usability in comparison to passwords. Most of the subjects agreed that Touch ID, indeed, offers usability benefits such as convenience, speed and ease of use. Finally, we found that there is a disconnect between users desires for security that their passcodes have to offer and the reality. In particular, only 12% of participants correctly estimated the security PIN-codes provide while the rest had unjustified expectations.
Evolution of Massive Haloes in non-Gaussian Scenarios
Creators: name: Grossi, M.
name: Dolag, K.
name: Branchini, E.
name: Matarrese, S.
name: Moscardini, L.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We have performed high-resolution cosmological N-body simulations of a concordance LCDM model to study the evolution of virialized, dark matter haloes in the presence of primordial non-Gaussianity. Following a standard procedure, departures from Gaussianity are modeled through a quadratic Gaussian term in the primordial gravitational potential, characterized by a dimensionless non-linearity strength parameter f_NL. We find that the halo mass function and its redshift evolution closely follow the analytic predictions of Matarrese et al.(2000). The existence of precise analytic predictions makes the observation of rare, massive objects at large redshift an even more attractive test to detect primordial non-Gaussian features in the large scale structure of the universe.
description: 7 pages,3 figures, submitted to MNRAS
Η αρχιτεκτονική γλυπτική της Αθήνας από την πρώιμη στη μέση βυζαντινή περίοδο
Creators: name: Θεοχάρης, Ιωάννης Ε.
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Βυζάντιο
Γλυπτική
Αθήνα
Byzantine
Sculpture
Athens

description: Η συγκεκριμένη διατριβή αποσκοπεί στην εξέταση της αρχιτεκτονικής γλυπτικής της Αθήνας από την πρώιμη στη μέση βυζαντινή περίοδο. Ως χρονικό πλαίσιο επιλέχθηκε η περίοδος από την ίδρυση του θέματος Ελλάδος έως την επίσκεψη του Βασιλείου Β΄ στην Αθήνα το 1018. Επανεξετάστηκαν τα κριτήρια με τα οποία προσεγγίσθηκε η γυπτική της λεγόμενης Αθηναϊκής Σχολής και εκείνης των «σκοτεινών χρόνων» της πόλης. Πυρήνας της διατριβής υπήρξε η εξέταση του γλυπτού διακόσμου τεσσάρων ναών της Αθήνας, που μετασκευάστηκαν σε χριστιανικές εκκλησίες: του Παρθενώνα, του Ερεχθείου, του Ηφαιστείου και του Ασκληπιείου. Μέσα από την επανεξέταση του γλυπτού τους διακόσμου επιχειρήθηκε η αναθεώρηση απόψεων σχετικά με το τέλος του παγανισμού και τη διάδοση του χριστιανισμού στην πόλη.
description: The present thesis aims at presenting the architectural sculpture in Athens from the Early to the Middle Byzantine Period. The historical frame of the our material is the period between the foundation of the theme of Hellas and the visit of Basil II to the city in 1018. In the first part of the thesis we reassessed the criteria for dating the sculptures of the so-called “Athenian School” and those of the “Dark Ages”. In the second part, the core of our study, we analyzed the marble decoration of four Athenian temples converted into Christian churches (the Parthenon, the Erechteion, the Hephaisteion and the Asclepieion). Through recounting the history of architectural sculpture in Athens, we proposed a new picture of the end of paganism and the establishment of the Christian religion in the city.
Precision wavelength calibration for Radial Velocity measurements using Uranium lines between 3800-6900 Å
Creators: name: Sharma, Rishikesh
name: Chakraborty, Abhijit
Publisher: name: arXiv
Year: 2021
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: We present here the precise wavelength calibration of a high-resolution spectrum using Uranium (U) lines in the wavelength range of 3809 - 6833 Å for precision radial velocity measurements for exoplanet detection or related astrophysical sciences. We identify 1540 well-resolved U lines from a high-resolution (R=67,000) spectrum of the uranium-argon hollow cathode lamp (UAr HCL) using PARAS spectrograph in the aforesaid wavelength range. We calculate the neutral and first allowed transitions (Ritz wavelength) of U from its known energy levels and compare them with our observed central wavelengths. We measure an offset of -0.15 mÅ\space in our final U line list. The line list has an average measurement uncertainty of 15 m s$^{-1}$ (0.013 pixels or 0.28 mÅ). We included these lines to the PARAS data analysis framework to perform the wavelength calibration and then calculate the multi-order Radial Velocity (RV) of PARAS spectra. The typical dispersion of residuals around the wavelength solution of a UAr spectrum, using U lines, is found to be 0.8 mÅ\space($\sim$45 m s$^{-1}$). With the use of this line list, we present our results for the precision RV of an on-sky source (A RV standard star), and an off-sky source (A HCL) observed with PARAS along with UAr HCL. We measure the dispersion in absolute drift difference between two fibers (inter-fiber drift) for a span of 6.5 hours to be 88 cm s$^{-1}$, and the RV dispersion (${σ_{RV}}$) for a RV standard star, HD55575 over the course of $\sim$450 days to be 3.2 m s$^{-1}$. These results are in good agreement with the previous ones measured using the ThAr HCL. It proves that the ThAr HCL with $\sim$ 99\% pure-Th are replaceable with the UAr HCL for the wavelength calibration of the high-resolution spectrographs such as PARAS (R $\leq$ 67,000) to achieve a RV precision of 1-3 m s$^{-1}$ in the visible region.
description: 15 pages, 8 figures, 1 long table, Published in SPIE-JATIS
Sound velocity and absorption measurements under high pressure using picosecond ultrasonics in diamond anvil cell. Application to the stability study of AlPdMn
Creators: name: Decremps, Frederic
name: Belliard, Laurent
name: Perrin, Bernard
name: Gauthier, Michel
Publisher: name: arXiv
Year: 2007
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We report an innovative high pressure method combining the diamond anvil cell device with the technique of picosecond ultrasonics. Such an approach allows to accurately measure sound velocity and attenuation of solids and liquids under pressure of tens of GPa, overcoming all the drawbacks of traditional techniques. The power of this new experimental technique is demonstrated in studies of lattice dynamics, stability domain and relaxation process in a metallic sample, a perfect single-grain AlPdMn quasicrystal, and rare gas, neon and argon. Application to the study of defect-induced lattice stability in AlPdMn up to 30 GPa is proposed. The present work has potential for application in areas ranging from fundamental problems in physics of solid and liquid state, which in turn could be beneficial for various other scientific fields as Earth and planetary science or material research.
Large radius exciton in single-walled carbon nanotubes
Creators: name: Adamyan, Vadym M.
name: Smyrnov, Oleksii A.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: The spectrum of large radius exciton in an individual semiconducting single-walled carbon nanotube (SWCNT) is described within the framework of elementary potential model, in which exciton is modeled as bound state of two oppositely charged quasi-particles confined on the tube surface. Due to the parity of the interaction potential the exciton states split into the odd and even series. It is shown that for the bare and screened Coulomb electron-hole (e-h) potentials the binding energy of even excitons in the ground state well exceeds the energy gap. The factors preventing the collapse of single-electron states in isolated semiconducting SWCNTs are discussed.
description: 14 pages, 1 figure, 5 tables
Positive and negative pressure effects on the magnetic ordering and the Kondo effect in the compound Ce2RhSi3
Creators: name: Nakano, T.
name: Sengupta, Kausik
name: Rayaprol, Sudhindra
name: Hedo, M.
name: Uwatoko, Y.
name: Sampathkumaran, E. V.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The competition between magnetic ordering and the Kondo effect in Ce2RhSi3, ordering antiferromagnetically at 7 K, is investigated by the measurements of magnetization, heat capacity and electrical resistivity on the solid solutions, Ce(2-x)La(x)RhSi3, Ce(2-y)Y(y)RhSi3, and Ce2RhSi(3-z)Ge(z), as well as by high pressure studies on this compound. The trends in the Kondo and Neel temperature variations among these alloys are compared to infer the roles of unit-cell volume and electronic structure changes. On the basis of the results, we infer that this compound lies at the peak of Doniach-magnetic-phase-diagram. The high pressure electrical resistivity data indicate that the quantum critical point for this compound is in the vicinity of 4 GPa.
Estimation of Tropical Cyclone Wind Using a Modified Jelesnianski's Pressure Model
Creators: name: Sasiwimon Pornprapai
Publisher: name: Mahasarakham University
Year: 2014
Subjects: Wind Model, Tropical Cyclone, Jelesnianki's Pressure Model, Typhoon Vamei

description: 2, 33, Journal of SCIENCE and TECHNOLOGY Mahasarakham University
Two-Loop Fermionic Corrections to Massive Bhabha Scattering
Creators: name: Actis, S.
name: Czakon, M.
name: Gluza, J.
name: Riemann, T.
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We evaluate the two-loop corrections to Bhabha scattering from fermion loops in the context of pure Quantum Electrodynamics. The differential cross section is expressed by a small number of Master Integrals with exact dependence on the fermion masses me, mf and the Mandelstam invariants s,t,u. We determine the limit of fixed scattering angle and high energy, assuming the hierarchy of scales me^2 << mf^2 << s,t,u. The numerical result is combined with the available non-fermionic contributions. As a by-product, we provide an independent check of the known electron-loop contributions.
description: 22 pages, 5 tables, 5 figures, eq. 4.9 corrected
Η ερυθρόμορφη κεραμική παραγωγή των εργαστηρίων Νικοσθένη και Παμφαίου:
Creators: name: Τόλια-Χριστάκου, Μαρία Β.
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Αρχαιολογία
Αγγειογραφία
Κεραμική
Εικονογραφία
Archaeology
Vase-painting
Pottery
Iconography

description: Η διδακτορική διατριβή εξετάζει την ερυθρόμορφη παραγωγή του Nικοσθένη και του Παμφαίου, δύο κεραμέων του αττικού Κεραμεικού των αρχαϊκών χρόνων. Βασικό πυρήνα της εργασίας αποτέλεσαν τα υπογεγραμμένα αγγεία τους, δέκα του Νικοσθένη και σαράντα πέντε του Παμφαίου. Εξετάστηκαν καταρχάς τα σχήματα των αγγείων που κατασκευάστηκαν στα εργαστήριά τους με τη βοήθεια δημοσιευμένων τομών, αλλά και μέσα από πρωτότυπα σχέδια που παράχθηκαν στα μουσεία από τη συγγραφέα. Σε αυτά περιελήφθησαν εκτός των υπογεγραμμένων και ανυπόγραφα αγγεία που βάσει των λεπτομερειών του σχήματος αποδόθηκαν σε κάποιο από τα εργαστήρια. Το μεγαλύτερο μέρος της εργασίας είναι αφιερωμένο στους αγγειογράφους που εργάστηκαν για τους δύο κεραμείς, τόσο εκείνους που διακόσμησαν αγγεία με τις υπογραφές των κεραμέων, όσο και στους αγγειογράφους των ανυπόγραφων. H ενδελεχής εξέταση του στυλ τους οδήγησε σε κάποιες περιπτώσεις σε νέες αποδόσεις ή αποσυσχετισμούς έργων που τους είχαν κατά καιρούς αποδοθεί. Με ενδελέχεια εξετάστηκαν και τα εικονογραφικά θέματα που τους απασχόλησαν. Στην εργασία εξετάζονται και επιμέρους θέματα, όπως οι επιγραφές στα αγγεία και οι τόποι εύρεσής τους, ενώ γίνεται προσπάθεια για τον προσδιορισμό απόλυτων χρονολογικών ορίων για την έναρξη και παύση της παραγωγής των δύο εργαστηρίων.
description: The doctoral thesis investigates the red-figure vase production by Nikosthenes and Pamphaios, two potters who worked in the Attic Kerameikos during the archaic period. The study focuses mainly on the vases bearing the potters’ signatures, ten by Nikosthenes and forty-five by Pamphaios. The first chapters examine the shapes of the vases produced in the potters’ workshops, based on published profile-drawings as well as drawings executed by the author. The thesis also studies unsigned vases attributed to either of the workshops on the basis of their profile details. A large part of the study concentrates on the painters who worked for the two potters, not only on those who decorated vases signed by them, but also on those of the unsigned ones. The detailed stylistic analysis led in many cases to either new vase attributions or dissociations. The iconographic themes depicted on the vase paintings were also studied in detail. Specific chapters examine the vase inscriptions and the places where the vases were found as well as chronological issues concerning the beginning and termination of the pottery production of the two workshops.
Navigation of a Self-Driving Vehicle Using One Fiducial Marker
Creators: name: Liu, Yibo
name: Schofield, Hunter
name: Shan, Jinjun
Publisher: name: arXiv
Year: 2021
Subjects: subject: Robotics (cs.RO)
subject: Image and Video Processing (eess.IV)
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: Navigation using only one marker, which contains four artificial features, is a challenging task since camera pose estimation using only four coplanar points suffers from the rotational ambiguity problem in a real-world application. This paper presents a framework of vision-based navigation for a self-driving vehicle equipped with multiple cameras and a wheel odometer. A multiple camera setup is presented for the camera cluster which has 360-degree vision such that our framework solely requires one planar marker. A Kalman-Filter-based fusion method is introduced for the multiple-camera and wheel odometry. Furthermore, an algorithm is proposed to resolve the rotational ambiguity problem using the prediction of the Kalman Filter as additional information. Finally, the lateral and longitudinal controllers are provided. Experiments are conducted to illustrate the effectiveness of the theory.
description: 6 pages, 9 figures
Gravitational Collapse to Toroidal and Higher Genus asymptotically AdS Black Holes
Creators: name: Mena, Filipe C.
name: Natario, Jose
name: Tod, Paul
Publisher: name: arXiv
Year: 2007
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Astrophysics (astro-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We match collapsing inhomogeneous as well as spatially homogeneous but anisotropic spacetimes to vacuum static exteriors with a negative cosmological constant and planar or hyperbolic symmetry. The collapsing interiors include the inhomogeneous solutions of Szekeres and of Barnes, which in turn include the Lemaitre-Tolman and the McVittie solutions. The collapse can result in toroidal or higher genus asymptotically AdS black holes.
description: 15 pages, 2 figures; v2: typos corrected, references added