Topology of Platonic Spherical Manifolds: From Homotopy to Harmonic Analysis
Kramer, Peter
2015-01-01
We carry out the harmonic analysis on four Platonic spherical three-manifolds with different topologies. Starting out from the homotopies (Everitt 2004), we convert them into deck operations, acting on the simply connected three-sphere as the cover, and obtain the corresponding variety of deck groups. For each topology, the three-sphere is tiled into copies of a fundamental domain under the corresponding deck group. We employ the point symmetry of each Platonic manifold to construct its fundamental domain as a spherical orbifold. While the three-sphere supports an~orthonormal complete basis for harmonic analysis formed by Wigner polynomials, a given spherical orbifold leads to a selection of a specific subbasis. The resulting selection rules find applications in cosmic topology, probed by the cosmic microwave background.
Yong, Ee Hou; Nelson, David R; Mahadevan, L
2013-10-25
On microscopic scales, the crystallinity of flexible tethered or cross-linked membranes determines their mechanical response. We show that by controlling the type, number, and distribution of defects on a spherical elastic shell, it is possible to direct the morphology of these structures. Our numerical simulations show that by deflating a crystalline shell with defects, we can create elastic shell analogs of the classical platonic solids. These morphologies arise via a sharp buckling transition from the sphere which is strongly hysteretic in loading or unloading. We construct a minimal Landau theory for the transition using quadratic and cubic invariants of the spherical harmonic modes. Our approach suggests methods to engineer shape into soft spherical shells using a frozen defect topology.
Socrates: Platonic Political Ideal
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Christopher P. Long
2012-08-01
Full Text Available This essay articulates the differences and suggests the similarities between the practices of Socratic political speaking and those of Platonic political writing. The essay delineates Socratic speaking and Platonic writing as both erotically oriented toward ideals capable of transforming the lives of individuals and their relationships with one another. Besides it shows that in the Protagoras the practices of Socratic political speaking are concerned less with Protagoras than with the individual young man, Hippocrates. In the Phaedo, this ideal of a Socrates is amplified in such a way that Platonic writing itself emerges as capable of doing with readers what Socratic speaking did with those he encountered. Socrates is the Platonic political ideal. The result is a picture of the transformative political power of Socratic speaking and Platonic writing both.
DEFF Research Database (Denmark)
Ostenfeld, Erik Nis
2011-01-01
Artiklen falder i to dele, en metodisk del og en gennemgang af hovedpunkter i Platons filosofi. Det er almindelig viden blandt oplyste, uddannede mennesker, at Platon er en af de vigtigste filosoffer overhovedet i den vesterlandske kultur. Dette illustreres af den indflydelse på filosofi......, litteratur og kultur, han har haft i de 2500 år, der er gået, siden han levede. Man mener også at vide, at Platons filosofi bl.a. indeholder forestillinger om en ideverden og en udødelig sjæl, der midlertidigt er havnet i en distraherende uvirkelig skyggeverden. Ved filosofiens hjælp kan den vende tilbage...... til skuet af ideerne. Hertil hører også billedet af den tredelte sjæl som en kusk med vognspand af to mere eller mindre uregerlige heste. Endelig er Platon forbundet med ideen om en idealstat regeret af filosoffer. Skønt alle disse forestillinger findes i Platons værk, er det ikke korrekt at antage...
DEFF Research Database (Denmark)
Ostenfeld, Erik Nis
2011-01-01
Artiklen falder i to dele, en metodisk del og en gennemgang af hovedpunkter i Platons filosofi. Det er almindelig viden blandt oplyste, uddannede mennesker, at Platon er en af de vigtigste filosoffer overhovedet i den vesterlandske kultur. Dette illustreres af den indflydelse på filosofi......, litteratur og kultur, han har haft i de 2500 år, der er gået, siden han levede. Man mener også at vide, at Platons filosofi bl.a. indeholder forestillinger om en ideverden og en udødelig sjæl, der midlertidigt er havnet i en distraherende uvirkelig skyggeverden. Ved filosofiens hjælp kan den vende tilbage...... til skuet af ideerne. Hertil hører også billedet af den tredelte sjæl som en kusk med vognspand af to mere eller mindre uregerlige heste. Endelig er Platon forbundet med ideen om en idealstat regeret af filosoffer. Skønt alle disse forestillinger findes i Platons værk, er det ikke korrekt at antage...
Directory of Open Access Journals (Sweden)
Maria Chiara Pievatolo
2014-03-01
Full Text Available L’ipertesto dedicata al Carmide di Platone, composto per l’uso degli studenti dell’ateneo pisano, è a disposizione di tutti qui. Il Carmide è – canonicamente – un dialogo aporetico. Ma almeno dei suoi paradossi – quello di una superscienza che pretende...
Directory of Open Access Journals (Sweden)
Maria Chiara Pievatolo
2013-01-01
Full Text Available Pensate che i testi antichi siano semplicemente vecchi? Che l’amore platonico non vada mai al sodo? Leggere il Simposio di Platone confrontandosi direttamente col testo, com’è possibile fare grazie al Perseus Project, vi farà cambiare idea.
Directory of Open Access Journals (Sweden)
Maria Chiara Pievatolo
2015-06-01
Full Text Available La guida ipertestuale alla lettura del Cratilo di Platone composta per gli studenti della facoltà di Scienze politiche dell’università di Pisa è ora visibile a tutti qui. L’ipertesto ha tratto vantaggio dall’Introduzione alla linguistica generale del professor Manuel Barbera dell’università...
Platons ‘respekt’ for Protagoras
DEFF Research Database (Denmark)
Bloch, David
2011-01-01
Platons forhold til sofisten Protagoras behandles. Hvor forskningen oftest har hævdet, at Platon har stor respekt for denne, argumenteres der her for, at Platons dialog "Protagoras" viser alt andet end respekt.......Platons forhold til sofisten Protagoras behandles. Hvor forskningen oftest har hævdet, at Platon har stor respekt for denne, argumenteres der her for, at Platons dialog "Protagoras" viser alt andet end respekt....
DEFF Research Database (Denmark)
Hellström, Anders; Hervik, Peter
2014-01-01
of fear, we argue, this predisposes people to vote for anti-immigration parties. Our analysis highlights the position of anti-immigration parties; hence, the Sweden Democrats (SD) in Sweden and the Danish People’s Party (DPP) in Denmark. We use frame analysis to detect recurrent frames in the media debate...... as such plays a similar role and provides the DPP with an identity. We conclude that we are confronted with a two-faced beast that feeds on perceptions of the people as ultimately afraid of what are not recognized as native goods....
DEFF Research Database (Denmark)
Sindbæk, Søren Michael
2012-01-01
of communities and their life world. Transcending technology, cultural dispositions and social relations, the study of innovations invites an actor-networks approach, which considers the heterogeneous nature of human-material relations. The archaeological record is potentially a rich source of evidence...... on innovations. Mostly, however, the time-resolution of archaeological data is too coarse-grained to allow us to grasp this potential to the full. In the period c. AD 790-850 a distinctly new artistic motif, the Gripping Beast, emerged in Scandinavia. A series of narrowly dated contexts provide anchor points...
Platonism, Naturalism, and Mathematical Knowledge
Brown, James Robert
2011-01-01
This study addresses a central theme in current philosophy: Platonism vs Naturalism and provides accounts of both approaches to mathematics, crucially discussing Quine, Maddy, Kitcher, Lakoff, Colyvan, and many others. Beginning with accounts of both approaches, Brown defends Platonism by arguing that only a Platonistic approach can account for concept acquisition in a number of special cases in the sciences. He also argues for a particular view of applied mathematics, a view that supports Platonism against Naturalist alternatives. Not only does this engaging book present the Platonist-Natural
Manton, Nicholas
2014-01-01
We construct a number of explicit examples of hyperbolic monopoles, with various charges and often with some platonic symmetry. The fields are obtained from instanton data in four-dimensional Euclidean space that are invariant under a circle action, and the monopole charge is equal to the instanton charge. A key ingredient is the identification of a new set of constraints on ADHM instanton data that are sufficient to ensure the circle invariance. Algebraic formulae for the Higgs field magnitude are given and from these we compute and illustrate the energy density of the monopoles. For particular monopoles, the explicit formulae provide a proof that the number of zeros of the Higgs field is greater than the monopole charge. We also present some one-parameter families of monopoles analogous to known scattering events for Euclidean monopoles within the geodesic approximation.
Origen and the Platonic Tradition
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Ilaria L.E. Ramelli
2017-02-01
Full Text Available This study situates Origen of Alexandria within the Platonic tradition, presenting Origenas a Christian philosopher who taught and studied philosophy, of which theology was part and parcel. More speciﬁcally, Origen can be described as a Christian Platonist. He criticized “false philosophies” as well as “heresies,” but not the philosophy of Plato. Against the background of recent scholarly debates, the thorny issue of the possible identity between Origen the Christian Platonist and Origen the Neoplatonist is partially addressed (although it requires a much more extensive discussion; it is also discussed in the light of Origen’s formation at Ammonius’s school and the reception of his works and ideas in “pagan” Platonism. As a consequence, and against scholarly perspectives that tend to see Christianity as anti-Platonism, the ﬁnal section of this paper asks the question of what is imperial and late antique Platonism and, on the basis of rich evidence ,suggests that this was not only “pagan” institutional Platonism.
Godel's Incompleteness Theorems and Platonic Metaphysics
Mikovic, Aleksandar
2015-01-01
We argue by using Godel's incompletness theorems in logic that platonism is the best metaphysics for science. This is based on the fact that a natural law in a platonic metaphysics represents a timeless order in the motion of matter, while a natural law in a materialistic metaphysics can be only defined as a temporary order which appears at random in the chaotic motion of matter. Although a logical possibility, one can argue that this type of metaphysics is highly implausible. Given that mathematics fits naturally within platonism, we conclude that a platonic metaphysics is more preferable than a materialistic metaphysics.
Platonism in Preface to Lyrical Ballads
Institute of Scientific and Technical Information of China (English)
严文烨
2016-01-01
Platonism has exerted great influence on Romanticism. Wordsworth, as the leading figure of English Romanticism, was inevitably influenced by Plato. Preface to Lyrical Ballads is Wordsworth's declaration of Romanticism. In this essay, the inheritance and innovation of Platonism in Preface to Lyrical Ballads is analyzed from three aspects: mimetic theories, pragmatism and expressive theories.
Platonic wholes and quantum ontology
Woszczek, Marek
2015-01-01
The subject of the book is a reconsideration of the internalistic model of composition of the Platonic type, more radical than traditional, post-Aristotelian externalistic compositionism, and its application in the field of the ontology of quantum theory. At the centre of quantum ontology is nonseparability. Quantum wholes are atemporal wholes governed by internalistic logic and they are primitive, global physical entities, requiring an extreme relativization of the fundamental notions of mechanics. That ensures quantum theory to be fully consistent with the relativistic causal structure, with
Faces of platonic solids in all dimensions
Szajewska, Marzena
2012-01-01
This paper considers Platonic solids/polytopes in the real Euclidean space R^n of dimension 3 <= n < infinity. The Platonic solids/polytopes are described together with their faces of dimensions 0 <= d <= n-1. Dual pairs of Platonic polytopes are considered in parallel. The underlying fi?nite Coxeter groups are those of simple Lie algebras of types An, Bn, Cn, F4 and of non-crystallographic Coxeter groups H3, H4. Our method consists in recursively decorating the appropriate Coxeter-Dynkin diagram. Each recursion step provides the essential information about faces of a speci?c dimension. If, at each recursion step, all of the faces are in the same Coxeter group orbit, i.e. are identical, the solid is called Platonic.
Platonic topology and CMB fluctuations: Homotopy, anisotropy, and multipole selection rules
Kramer, Peter
2009-01-01
The Cosmic Microwave Background CMB originates from an early stage in the history of the universe. Observed low multipole contributions of CMB fluctuations have motivated the search for selection rules from the underlying topology of 3-space. Everitt (2004) has generated all homotopies for Platonic spherical 3-manifolds by face gluings. We transform the glue generators into isomorphic deck transformations. The deck transformations act on a spherical Platonic 3-manifold as prototile and tile the 3-sphere by its images. A complete set of orthonormal functions on the 3-sphere is spanned by the Wigner harmonic polynomials. For a tetrahedral, two cubic and three octahedral manifolds we construct algebraically linear combinations of Wigner polynomials, invariant under deck transformations and with domain the manifold. We prove boundary conditions on polyhedral faces from homotopy. By algebraic means we pass to a multipole expansion. Assuming random models of the CMB radiation, we derive multipole selection rules, d...
BEAST: Bayesian evolutionary analysis by sampling trees
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Drummond Alexei J
2007-11-01
Full Text Available Abstract Background The evolutionary analysis of molecular sequence variation is a statistical enterprise. This is reflected in the increased use of probabilistic models for phylogenetic inference, multiple sequence alignment, and molecular population genetics. Here we present BEAST: a fast, flexible software architecture for Bayesian analysis of molecular sequences related by an evolutionary tree. A large number of popular stochastic models of sequence evolution are provided and tree-based models suitable for both within- and between-species sequence data are implemented. Results BEAST version 1.4.6 consists of 81000 lines of Java source code, 779 classes and 81 packages. It provides models for DNA and protein sequence evolution, highly parametric coalescent analysis, relaxed clock phylogenetics, non-contemporaneous sequence data, statistical alignment and a wide range of options for prior distributions. BEAST source code is object-oriented, modular in design and freely available at http://beast-mcmc.googlecode.com/ under the GNU LGPL license. Conclusion BEAST is a powerful and flexible evolutionary analysis package for molecular sequence variation. It also provides a resource for the further development of new models and statistical methods of evolutionary analysis.
Spherical Orbifolds for Cosmic Topology
Kramer, Peter
2012-01-01
Harmonic analysis is a tool to infer cosmic topology from the measured astrophysical cosmic microwave background CMB radiation. For overall positive curvature, Platonic spherical manifolds are candidates for this analysis. We combine the specific point symmetry of the Platonic manifolds with their deck transformations. This analysis in topology leads from manifolds to orbifolds. We discuss the deck transformations of the orbifolds and give basis functions for the harmonic analysis as linear combinations of Wigner polynomials on the 3-sphere. They provide new tools for detecting cosmic topology from the CMB radiation.
DEFF Research Database (Denmark)
Olsen, Anne-Marie Eggert
2015-01-01
Artiklen præsenterer i første del (A) det pædagogiske stof fra Platons Staten og Lovene, som Rousseau har læst og fundet inspiration i. Der plæderes for, at Rousseau optager og transponerer såvel principper som konkrete overvejelser uanset den forskelige historiske kontekst og de dermed sammenhæn......Artiklen præsenterer i første del (A) det pædagogiske stof fra Platons Staten og Lovene, som Rousseau har læst og fundet inspiration i. Der plæderes for, at Rousseau optager og transponerer såvel principper som konkrete overvejelser uanset den forskelige historiske kontekst og de dermed...... sammenhængende forskellige udformninger og mål for opdragelsen. I anden del (B) diskuteres Rousseaus ’platonisme’ i mere overordnet filosofisk sammenhæng, og der argumenteres for, at Rousseaus utraditionelle, pædagogisk-filosofiske Platon-læsning dels kan ses at fremdrage underbelyste centrale tematikker i...... Platons filosofi, dels understreger deres stadige aktualitet....
Plato's problem an introduction to mathematical platonism
Panza, M
2013-01-01
What is mathematics about? And how can we have access to the reality it is supposed to describe? The book tells the story of this problem, first raised by Plato, through the views of Aristotle, Proclus, Kant, Frege, Gödel, Benacerraf, up to the most recent debate on mathematical platonism.
Escaping the mythical beast: Gender mainstreaming reconceptualised
Eerdewijk, A.H.J.M. van; Davids, T.
2014-01-01
Since the early 2000s, disappointment has grown about the realization of the transformative potential that was ascribed to gender mainstreaming at its launch at the Beijing conference in 1995. The critiques on gender mainstreaming tend to represent gender mainstreaming as a 'mythical beast', and as
Flexural Mie Resonances: Localized Surface Platonic Modes
Farhat, M; Chen, P Y; Salama, K N; Bagci, H
2016-01-01
Surface plasmons polaritons were thought to exist only in metals near their plasma frequencies. The concept of spoof plasmons extended the realms of plasmonics to domains such as radio frequencies, magnetism, or even acoustic waves. Here, we introduce the concept of localized surface platonic modes (SPMs). We demonstrate that they can be generated on a two-dimensional clamped (or stress-free) cylindrical surface, in a thin elastic plate, with subwavelength corrugations under excitation by an incident flexural plane wave. Our results show that the corrugated rigid surface is elastically equivalent to a cylindrical scatterer with negatively uniform and dispersive flexural rigidity. This, indeed, suggests that plasmonic-like platonic materials can be engineered with potential applications in various areas including earthquake sensing, or elastic imaging and cloaking.
The origin of the division between Middle Platonism and Neoplatonism
DEFF Research Database (Denmark)
Catana, Leo
2013-01-01
The division of Ancient Platonism into Middle Platonism and Neoplatonism is a fairly new one. The conceptual foundation of this division was cemented in Jacob Brucker’s pioneering Historia critica philosophiae (1742-44). In the 1770s and 1780s, the term ‘Neoplatonism’ was coined on the basis...... of Brucker’s analysis. Three historiographical concepts were decisive to Brucker: ‘system of philosophy’, ‘eclecticism’ and ‘syncretism’. By means of these concepts, he characterized Middle Platonism and Neoplatonism as opposing philosophical movements, the former being a genuine form of Platonism...
Die Aufgabe des Gesetzes bei Solon und Platon
Marti, Urs
2011-01-01
Solon und Platon werden in der Literatur häufig in einem Zug genannt. Bereits Solon habe das Gesetz verstanden als Instrument zur Überwindung einer politischen Unordnung, die aus der mangelnden moralischen Qualifikation der Bürger resultiere. Die verbreitete Ansicht, Solon habe die politische Philosophie Platons vorweggenommen, bedarf der kritischen Prüfung. Tatsächlich versteht Platon unter Politik primär die moralische Erziehung der Bürger, während soziale Konflikte als Ursachen der Unordnu...
Architecture of Platonic and Archimedean polyhedral links
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
A new methodology for understanding the construction of polyhedral links has been developed on the basis of the Platonic and Archimedean solids by using our method of the 'three-cross-curve and doubletwist-line covering'. There are five classes of polyhedral links that can be explored: the tetrahedral and truncated tetrahedral links; the hexahedral and truncated hexahedral links; the dodecahedral and truncated dodecahedral links; the truncated octahedral and icosahedral links. Our results show that the tetrahedral and truncated tetrahedral links have T symmetry; the hexahedral and truncated hexahedral links, as well as the truncated octahedral links, O symmetry; the dodecahedral and truncated dodecahedral links, as well as the truncated icosahedral links, I symmetry, respectively. This study provides further insight into the molecular design, as well as theoretical characterization, of the DNA and protein catenanes.
Architecture of Platonic and Archimedean polyhedral links
Institute of Scientific and Technical Information of China (English)
2008-01-01
A new methodology for understanding the construction of polyhedral links has been developed on the basis of the Platonic and Archimedean solids by using our method of the ‘three-cross-curve and dou- ble-twist-line covering’. There are five classes of polyhedral links that can be explored: the tetrahedral and truncated tetrahedral links; the hexahedral and truncated hexahedral links; the dodecahedral and truncated dodecahedral links; the truncated octahedral and icosahedral links. Our results show that the tetrahedral and truncated tetrahedral links have T symmetry; the hexahedral and truncated hexahedral links, as well as the truncated octahedral links, O symmetry; the dodecahedral and truncated dodeca- hedral links, as well as the truncated icosahedral links, I symmetry, respectively. This study provides further insight into the molecular design, as well as theoretical characterization, of the DNA and protein catenanes.
Platonic solids in $\\mathbb Z^3$
Ionascu, Eugen J
2009-01-01
Extending previous results on a characterization of all equilateral triangle in space having vertices with integer coordinates ("in $\\mathbb Z^3$"), we look at the problem of characterizing all regular polyhedra (Platonic Solids) with the same property. To summarize, we show first that there is no regular icosahedron/ dodecahedron in $\\mathbb Z^3$. On the other hand, there is a finite (6 or 12) class of regular tetrahedra in $\\mathbb Z^3$, associated naturally to each nontrivial solution $(a,b,c,d)$ of the Diophantine equation $a^2+b^2+c^2=3d^2$ and for every nontrivial integer solution $(m,n,k)$ of the equation $m^2-mn+n^2=k^2$. Every regular tetrahedron in $\\mathbb Z^3$ belongs, up to an integer translation and/or rotation, to one of these classes. We then show that each such tetrahedron can be completed to a cube with integer coordinates. The study of regular octahedra is reduced to the cube case via the duality between the two. This work allows one to basically give a description the orthogonal group $O(3...
Searching for integrable Hamiltonian systems with Platonic symmetries
Rastelli, Giovanni
2010-01-01
In this paper we try to find examples of integrable natural Hamiltonian systems on the sphere $S^2$ with the symmetries of each Platonic polyhedra. Although some of these systems are known, their expression is extremely complicated; we try here to find the simplest possible expressions for this kind of dynamical systems. Even in the simplest cases it is not easy to prove their integrability by direct computation of the first integrals, therefore, we make use of numerical methods to provide evidences of integrability; namely, by analyzing their Poincar\\'e sections (surface sections). In this way we find three systems with platonic symmetries, one for each class of equivalent Platonic polyhedra: tetrahedral, exahedral-octahedral, dodecahedral-icosahedral, showing evidences of integrability. The proof of integrability and the construction of the first integrals are left for further works. As an outline of the possible developments if the integrability of these systems will be proved, we show how to build from th...
Impact of Platon ETC system on intercity trucking cost
Directory of Open Access Journals (Sweden)
Pogotovkina Natalya
2017-01-01
Full Text Available In 2015 Platon ETC System, a system of charging trucks with gross vehicle weight exceeding 12 tons, was implemented in Russia. The payment is collected as a compensation fo0 the damage caused to the federal public roads. Platon system is an additional source of financing for the road sector. However, its implementation made the carriers face the increasing costs. This paper presents the first results of the system functioning and the problems, associated with it. We consider the foreign systems of truck charging. The results of calculations, which show the effect of the toll collection on the prime cost of road freight transportation, are also presented.
Galactic foreground contribution to the BEAST CMB Anisotropy Maps
Mejia, J; Burigana, C; Childers, J; Figueiredo, N; Kangas, M; Lubin, P; Maino, D; Mandolesi, N; Marvil, J; Meinhold, P; O'Dwyer, I; O'Neill, H; Platania, P; Seiffert, M; Stebor, N; Tello, C A S; Villela, T; Wandelt, B; Wünsche, C A; Mej\\'{\\i}a, Jorge; Bersanelli, Marco; Burigana, Carlo; Childers, Jeff; Figueiredo, Newton; Kangas, Miikka; Lubin, Philip; Maino, Davide; Mandolesi, Nazzareno; Marvil, Josh; Meinhold, Peter; Dwyer, Ian O'; Neill, Hugh O'; Platania, Paola; Seiffert, Michael; Stebor, Nathan; Tello, Camilo; Villela, Thyrso; Wandelt, Benjamin; Wuensche, Carlos Alexandre
2004-01-01
We report limits on the Galactic foreground emission contribution to the Background Emission Anisotropy Scanning Telescope (BEAST) Ka- and Q-band CMB anisotropy maps. We estimate the contribution from the cross-correlations between these maps and the foreground emission templates of an H${\\alpha}$ map, a de-striped version of the Haslam et al. 408 MHz map, and a combined 100 $\\mu$m IRAS/DIRBE map. Our analysis samples the BEAST $\\sim10^\\circ$ declination band into 24 one-hour (RA) wide sectors with $\\sim7900$ pixels each, where we calculate: (a) the linear correlation coefficient between the anisotropy maps and the templates; (b) the coupling constants between the specific intensity units of the templates and the antenna temperature at the BEAST frequencies and (c) the individual foreground contributions to the BEAST anisotropy maps. The peak sector contributions of the contaminants in the Ka-band are of 56.5% free-free with a coupling constant of $8.3\\pm0.4$ $\\mu$K/R, and 67.4% dust with $45.0\\pm2.0$ $\\mu$K/...
Piiskop Platoni protest saksa okupatsiooni vastu a. 1918 / Piiskop Platon
Platon, Eesti Apostlik-Õigeusu kiriku peapiiskop, 1869-1919
1987-01-01
Piiskop Platon (kodanikunimega Paul Kulbusch) kirjeldab saksa okupatsiooni Eestis ja Lätis, Riia õigeusu kirikute ümberehitamist luteri kirikuteks, preestrite tagakiusamist ja väljasaatmist. A. Piibule Londonisse lääneriikide esindajatele levitamiseks saadetud pöördumise tekstile eelneb Esmo Ridala sissejuhatus ülevaatega piiskop Platoni eluloost
I grandi della fisica da Platone a Heisenberg
Von Weizsäcker, Carl Friedrich
2002-01-01
Parmenide ; Platone ; Aristotele ; Copernico, Keplero, Galilei ; Galileo Galilei ; Cartesio ; Gottfried Wilhelm Leibniz ; Cartesio, Newton, Leibniz, Kant ; Immanuel Kant ; Johann Wolfgang Goethe ; Robert Meyer ; Albert Einstein ; Niels Bohr ; Paul Adrien Maurice Dirac ; Niels Bohr e Werner Heisenberg, un ricordo del 1932 ; Werner Heisenberg ; Heisenberg, fisico e filosofo ; l'interpretazione filosofica della fisica moderna.
Platonic solids generate their four-dimensional analogues
Dechant, Pierre-Philippe
2013-01-01
In this paper, we show how regular convex 4-polytopes - the analogues of the Platonic solids in four dimensions - can be constructed from three-dimensional considerations concerning the Platonic solids alone. Via the Cartan-Dieudonne theorem, the reflective symmetries of the Platonic solids generate rotations. In a Clifford algebra framework, the space of spinors generating such three-dimensional rotations has a natural four-dimensional Euclidean structure. The spinors arising from the Platonic Solids can thus in turn be interpreted as vertices in four-dimensional space, giving a simple construction of the 4D polytopes 16-cell, 24-cell, the F_4 root system and the 600-cell. In particular, these polytopes have `mysterious' symmetries, that are almost trivial when seen from the three-dimensional spinorial point of view. In fact, all these induced polytopes are also known to be root systems and thus generate rank-4 Coxeter groups, which can be shown to be a general property of the spinor construction. These cons...
Piiskop Platoni protest saksa okupatsiooni vastu a. 1918 / Piiskop Platon
Platon, Eesti Apostlik-Õigeusu kiriku peapiiskop, 1869-1919
1987-01-01
Piiskop Platon (kodanikunimega Paul Kulbusch) kirjeldab saksa okupatsiooni Eestis ja Lätis, Riia õigeusu kirikute ümberehitamist luteri kirikuteks, preestrite tagakiusamist ja väljasaatmist. A. Piibule Londonisse lääneriikide esindajatele levitamiseks saadetud pöördumise tekstile eelneb Esmo Ridala sissejuhatus ülevaatega piiskop Platoni eluloost
A platonic solid templating Archimedean solid: an unprecedented nanometre-sized Ag37 cluster
Li, Xiao-Yu; Su, Hai-Feng; Yu, Kai; Tan, Yuan-Zhi; Wang, Xing-Po; Zhao, Ya-Qin; Sun, Di; Zheng, Lan-Sun
2015-04-01
The spontaneous formation of discrete spherical nanosized molecules is prevalent in nature, but the authentic structural mimicry of such highly symmetric polyhedra from edge sharing of regular polygons has remained elusive. Here we present a novel ball-shaped {(HNEt3)[Ag37S4(SC6H4tBu)24(CF3COO)6(H2O)12]} cluster (1) that is assembled via a one-pot process from polymeric {(HNEt3)2[Ag10(SC6H4tBu)12]}n and CF3COOAg. Single crystal X-ray analysis confirmed that 1 is a Td symmetric spherical molecule with a [Ag36(SC6H4tBu)24] anion shell enwrapping a AgS4 tetrahedron. The shell topology of 1 belongs to one of 13 Archimedean solids, a truncated tetrahedron with four edge-shared hexagons and trigons, which are supported by a AgS4 Platonic solid in the core. Interestingly, the cluster emits green luminescence centered at 515 nm at room temperature. Our investigations have provided a promising synthetic protocol for a high-nuclearity silver cluster based on underlying geometrical principles.The spontaneous formation of discrete spherical nanosized molecules is prevalent in nature, but the authentic structural mimicry of such highly symmetric polyhedra from edge sharing of regular polygons has remained elusive. Here we present a novel ball-shaped {(HNEt3)[Ag37S4(SC6H4tBu)24(CF3COO)6(H2O)12]} cluster (1) that is assembled via a one-pot process from polymeric {(HNEt3)2[Ag10(SC6H4tBu)12]}n and CF3COOAg. Single crystal X-ray analysis confirmed that 1 is a Td symmetric spherical molecule with a [Ag36(SC6H4tBu)24] anion shell enwrapping a AgS4 tetrahedron. The shell topology of 1 belongs to one of 13 Archimedean solids, a truncated tetrahedron with four edge-shared hexagons and trigons, which are supported by a AgS4 Platonic solid in the core. Interestingly, the cluster emits green luminescence centered at 515 nm at room temperature. Our investigations have provided a promising synthetic protocol for a high-nuclearity silver cluster based on underlying geometrical principles
CMB radiation in an inhomogeneous spherical space
Aurich, R; Lustig, S
2011-01-01
We analyse the CMB radiation in spherical 3-spaces with non-trivial topology. The focus is put on an inhomogeneous space which possesses observer dependent CMB properties. The suppression of the CMB anisotropies on large angular scales is analysed with respect to the position of the CMB observer. The equivalence of a lens space with a Platonic cubic space is shown and used for the harmonic analysis. We give the transformation of the CMB multipole radiation amplitude as a function of the position of the observer. General sum rules are obtained in terms of the squares of the expansion coefficients for invariant polynomials on the 3-sphere.
Erotic Wisdom and the Socratic Vocation in Plutarch’s Platonic Question 1
Directory of Open Access Journals (Sweden)
Mark Shiffman
2010-11-01
Full Text Available Plutarch's skeptical Platonism is embodied in his understanding of Socrates and Socrates' use of eros, and serves to harmonize his use of the skeptical heritage with his understanding of central Platonic teachings: questioning is the crucial tool in the search for wisdom.
Flat Zipper-Unfolding Pairs for Platonic Solids
O'Rourke, Joseph
2010-01-01
We show that four of the five Platonic solids' surfaces may be cut open with a Hamiltonian path along edges and unfolded to a polygonal net each of which can "zipper-refold" to a flat doubly covered parallelogram, forming a rather compact representation of the surface. Thus these regular polyhedra have particular flat "zipper pairs." No such zipper pair exists for a dodecahedron, whose Hamiltonian unfoldings are "zip-rigid." This report is primarily an inventory of the possibilities, and raises more questions than it answers.
Living donor kidney transplantation: "beauty and the beast"!
Danovitch, Gabriel M
2013-01-01
The report by Terasaki and colleagues in 1995 that the outcomes of spousal and biologically unrelated transplants were essentially the same as for 1-haplotype matched living related transplants changed the course of clinical transplantation. This article, entitled metaphorically "Beauty and the Beast", describes the dramatic change in the practice of living donor transplantation that followed. In the ensuing two decades, biologically unrelated living donor transplantation became commonplace in the developed world and reached its apotheosis in cross-country living donor paired exchange programs that have made transplantation accessible to many whose donors were deemed "incompatible". Such exchanges can indeed be thought of as a "thing of beauty". Sadly, the same observation was abused to exploit vulnerable donors, and the "beast" in the form of transplant tourism became a feature of transplantation in the developing world. The responsibility of the transplant community to protect the welfare of living donors and their recipients and the key role of trust in the evaluation of living donors is discussed.
BEASTling: A software tool for linguistic phylogenetics using BEAST 2
Forkel, Robert; Kaiping, Gereon A.; Atkinson, Quentin D.
2017-01-01
We present a new open source software tool called BEASTling, designed to simplify the preparation of Bayesian phylogenetic analyses of linguistic data using the BEAST 2 platform. BEASTling transforms comparatively short and human-readable configuration files into the XML files used by BEAST to specify analyses. By taking advantage of Creative Commons-licensed data from the Glottolog language catalog, BEASTling allows the user to conveniently filter datasets using names for recognised language families, to impose monophyly constraints so that inferred language trees are backward compatible with Glottolog classifications, or to assign geographic location data to languages for phylogeographic analyses. Support for the emerging cross-linguistic linked data format (CLDF) permits easy incorporation of data published in cross-linguistic linked databases into analyses. BEASTling is intended to make the power of Bayesian analysis more accessible to historical linguists without strong programming backgrounds, in the hopes of encouraging communication and collaboration between those developing computational models of language evolution (who are typically not linguists) and relevant domain experts. PMID:28796784
Astronomers Find Rare Beast by New Means
2010-01-01
For the first time, astronomers have found a supernova explosion with properties similar to a gamma-ray burst, but without seeing any gamma rays from it. The discovery, using the National Science Foundation's Very Large Array (VLA) radio telescope, promises, the scientists say, to point the way toward locating many more examples of these mysterious explosions. "We think that radio observations will soon be a more powerful tool for finding this kind of supernova in the nearby Universe than gamma-ray satellites," said Alicia Soderberg, of the Harvard-Smithsonian Center for Astrophysics. The telltale clue came when the radio observations showed material expelled from the supernova explosion, dubbed SN2009bb, at speeds approaching that of light. This characterized the supernova, first seen last March, as the type thought to produce one kind of gamma-ray burst. "It is remarkable that very low-energy radiation, radio waves, can signal a very high-energy event," said Roger Chevalier of the University of Virginia. When the nuclear fusion reactions at the cores of very massive stars no longer can provide the energy needed to hold the core up against the weight of the rest of the star, the core collapses catastrophically into a superdense neutron star or black hole. The rest of the star's material is blasted into space in a supernova explosion. For the past decade or so, astronomers have identified one particular type of such a "core-collapse supernova" as the cause of one kind of gamma-ray burst. Not all supernovae of this type, however, produce gamma-ray bursts. "Only about one out of a hundred do this," according to Soderberg. In the more-common type of such a supernova, the explosion blasts the star's material outward in a roughly-spherical pattern at speeds that, while fast, are only about 3 percent of the speed of light. In the supernovae that produce gamma-ray bursts, some, but not all, of the ejected material is accelerated to nearly the speed of light. The superfast
Music May Soothe the 'Savage Beast' of Post-Op Pain
... page: https://medlineplus.gov/news/fullstory_164526.html Music May Soothe the 'Savage Beast' of Post-Op ... pain and anxiety, but new research shows that music therapy may help ease their discomfort. Medication is ...
Controlling flexural waves in semi-infinite platonic crystals
Haslinger, Stewart G; Movchan, Alexander B; Jones, Ian S; Craster, Richard V
2016-01-01
We address the problem of scattering and transmission of a plane flexural wave through a semi-infinite array of point scatterers/resonators, which take a variety of physically interesting forms. The mathematical model accounts for several classes of point defects, including mass-spring resonators attached to the top surface of the flexural plate and their limiting case of concentrated point masses. We also analyse the special case of resonators attached to opposite faces of the plate. The problem is reduced to a functional equation of the Wiener-Hopf type, whose kernel varies with the type of scatterer considered. A novel approach, which stems from the direct connection between the kernel function of the semi-infinite system and the quasi-periodic Green's functions for corresponding infinite systems, is used to identify special frequency regimes. We thereby demonstrate dynamically anisotropic wave effects in semi-infinite platonic crystals, with particular attention paid to designing systems to exhibit dynami...
The Panchromatic Hubble Andromeda Treasury. XV. The BEAST: Bayesian Extinction and Stellar Tool
Gordon, Karl D.; Fouesneau, Morgan; Arab, Heddy; Tchernyshyov, Kirill; Weisz, Daniel R.; Dalcanton, Julianne J.; Williams, Benjamin F.; Bell, Eric F.; Bianchi, Luciana; Boyer, Martha; Choi, Yumi; Dolphin, Andrew; Girardi, Léo; Hogg, David W.; Kalirai, Jason S.; Kapala, Maria; Lewis, Alexia R.; Rix, Hans-Walter; Sandstrom, Karin; Skillman, Evan D.
2016-08-01
We present the Bayesian Extinction And Stellar Tool (BEAST), a probabilistic approach to modeling the dust extinguished photometric spectral energy distribution of an individual star while accounting for observational uncertainties common to large resolved star surveys. Given a set of photometric measurements and an observational uncertainty model, the BEAST infers the physical properties of the stellar source using stellar evolution and atmosphere models and constrains the line of sight extinction using a newly developed mixture model that encompasses the full range of dust extinction curves seen in the Local Group. The BEAST is specifically formulated for use with large multi-band surveys of resolved stellar populations. Our approach accounts for measurement uncertainties and any covariance between them due to stellar crowding (both systematic biases and uncertainties in the bias) and absolute flux calibration, thereby incorporating the full information content of the measurement. We illustrate the accuracy and precision possible with the BEAST using data from the Panchromatic Hubble Andromeda Treasury. While the BEAST has been developed for this survey, it can be easily applied to similar existing and planned resolved star surveys. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
Wenninger, Magnus J
2012-01-01
Well-illustrated, practical approach to creating star-faced spherical forms that can serve as basic structures for geodesic domes. Complete instructions for making models from circular bands of paper with just a ruler and compass. Discusses tessellation, or tiling, and how to make spherical models of the semiregular solids and concludes with a discussion of the relationship of polyhedra to geodesic domes and directions for building models of domes. "". . . very pleasant reading."" - Science. 1979 edition.
The Panchromatic Hubble Andromeda Treasury XV. The BEAST: Bayesian Extinction and Stellar Tool
Gordon, Karl D; Arab, Heddy; Tchernyshyov, Kirill; Weisz, Daniel R; Dalcanton, Julianne J; Williams, Benjamin F; Bell, Eric F; Bianchi, Luciana; Boyer, Martha; Choi, Yumi; Dolphin, Andrew; Girardi, Leo; Hogg, David W; Kalirai, Jason S; Kapala, Maria; Lewis, Alexia R; Rix, Hans-Walter; Sandstrom, Karin; Skillman, Evan D
2016-01-01
We present the Bayesian Extinction And Stellar Tool (BEAST), a probabilistic approach to modeling the dust extinguished photometric spectral energy distribution of an individual star while accounting for observational uncertainties common to large resolved star surveys. Given a set of photometric measurements and an observational uncertainty model, the BEAST infers the physical properties of the stellar source using stellar evolution and atmosphere models and constrains the line of sight extinction using a newly developed mixture model that encompasses the full range of dust extinction curves seen in the Local Group. The BEAST is specifically formulated for use with large multi-band surveys of resolved stellar populations. Our approach accounts for measurement uncertainties and any covariance between them due to stellar crowding (both systematic biases and uncertainties in the bias) and absolute flux calibration, thereby incorporating the full information content of the measurement. We illustrate the accuracy...
A Persistent Back-End for the ATLAS Online Information Service (P-BEAST)
SICOE, A D; The ATLAS collaboration; KOLOS, S; MAGNONI, L; SOLOVIEV, I
2012-01-01
This poster describes P-BEAST, a highly scalable, highly available and durable system for archiving monitoring information of the trigger and data acquisition (TDAQ) system of the ATLAS experiment. Currently this consists of 20,000 applications running on 2,400 interconnected computers but it is foreseen to grow further in the near future. P-BEAST stores considerable amounts of monitoring information which would otherwise be lost. Making this data accessible, facilitates long term analysis and faster debugging. The novelty of this research consists of using a modern key-value storage technology (Cassandra) to satisfy the large time series data rates, flexibility and scalability requirements entailed by the project. The loose schema allows the stored data to evolve seamlessly with the information flowing within the Information Service. An architectural overview of P-BEAST is presented together with a discussion on the arguments which ultimately lead to choosing Cassandra as the storage technology. Measurements...
Readings of Platonic Virtue Theories from the Middle Ages to the Renaissance
DEFF Research Database (Denmark)
Catana, Leo
2014-01-01
It is commonly known that ancient schools of ethics were revived during the Renaissance: The texts pertaining to Platonic, Aristotelian, Stoic and Epicurean ethics were edited, translated and discussed in this period. It is less known that the Renaissance also witnessed a revival of Plotinian...... ethics, by then perceived as a legitimate form of Platonic ethics. Plotinus’ ethics had been transmitted through the Middle Ages through Macrobius’ Latin treatise In somnium Scipionis I.8, which relied heavily on Plotinus’ student, Porphyry, and his report of Plotinus’ ethics. In this article...... it is argued that the Florentine humanist and philosopher Marsilio Ficino carried on this tradition of Platonic, or rather Plotinian, ethics. He was familiar with Plotinus’ Enneads, since he had had access to it through Greek manuscripts from around 1462; his Latin translation of the Enneads was published...
Efficient methods for solving discrete topology design problems in the PLATO-N project
DEFF Research Database (Denmark)
Canh, Nam Nguyen; Stolpe, Mathias
This paper considers the general multiple load structural topology design problems in the framework of the PLATO-N project. The problems involve a large number of discrete design variables and were modeled as a non-convex mixed 0–1 program. For the class of problems considered, a global optimizat......This paper considers the general multiple load structural topology design problems in the framework of the PLATO-N project. The problems involve a large number of discrete design variables and were modeled as a non-convex mixed 0–1 program. For the class of problems considered, a global...
Book Review: Zöllner, Hans-Bernd, The Beast and the Beauty: ...
Directory of Open Access Journals (Sweden)
Grit Grigoleit
2012-01-01
Full Text Available Book Review of the monograph: Zöllner, Hans-Bernd (2012, The Beast and the Beauty: The History of the Conflict between the Military and Aung San Suu Kyi in Myanmar, 1988–2011, Set in a Global Context Berlin: regiospectra Verlag, ISBN: 978-3-9401-3244-4, 592 pages
Taming the Publishing Beast: The College of St. Catherine Scholars' Retreat
Farr, Cecilia Konchar; Cavallaro, Joanne; Civil, Gabrielle; Cochrane, Susan
2009-01-01
Publishing is the sleeping beast that faculty at college like the College of St. Catherine, a 5,000-student women's college in Minnesota's Twin Cities, have tiptoed around for years. Here, as in many institutions devoted to undergraduate teaching, professors could once amble undisturbed along the promotion path equipped only with pedagogical…
Fear of the beast: a prospective study on the effects of negative information on childhood fear
Muris, P.E.H.M.; Bodden, D.H.M.; Merckelbach, H.L.G.J.; Ollendick, T.H.; King, N.J.
2003-01-01
The current study examined the effects of negative information on the enhancement of childhood fear. A large group of normal primary school children aged between 4 and 12 years (N=285) received either negative or positive information about an unknown, doglike animal, called 'the beast'. Children's f
πBUSS: a parallel BEAST/BEAGLE utility for sequence simulation under complex evolutionary scenarios.
Bielejec, Filip; Lemey, Philippe; Carvalho, Luiz Max; Baele, Guy; Rambaut, Andrew; Suchard, Marc A
2014-05-07
Simulated nucleotide or amino acid sequences are frequently used to assess the performance of phylogenetic reconstruction methods. BEAST, a Bayesian statistical framework that focuses on reconstructing time-calibrated molecular evolutionary processes, supports a wide array of evolutionary models, but lacked matching machinery for simulation of character evolution along phylogenies. We present a flexible Monte Carlo simulation tool, called πBUSS, that employs the BEAGLE high performance library for phylogenetic computations to rapidly generate large sequence alignments under complex evolutionary models. πBUSS sports a user-friendly graphical user interface (GUI) that allows combining a rich array of models across an arbitrary number of partitions. A command-line interface mirrors the options available through the GUI and facilitates scripting in large-scale simulation studies. πBUSS may serve as an easy-to-use, standard sequence simulation tool, but the available models and data types are particularly useful to assess the performance of complex BEAST inferences. The connection with BEAST is further strengthened through the use of a common extensible markup language (XML), allowing to specify also more advanced evolutionary models. To support simulation under the latter, as well as to support simulation and analysis in a single run, we also add the πBUSS core simulation routine to the list of BEAST XML parsers. πBUSS offers a unique combination of flexibility and ease-of-use for sequence simulation under realistic evolutionary scenarios. Through different interfaces, πBUSS supports simulation studies ranging from modest endeavors for illustrative purposes to complex and large-scale assessments of evolutionary inference procedures. Applications are not restricted to the BEAST framework, or even time-measured evolutionary histories, and πBUSS can be connected to various other programs using standard input and output format.
Run away from Spiritual Emptiness——An Analysis of the Theme of The Beast in the Jungle
Institute of Scientific and Technical Information of China (English)
尹贤
2015-01-01
The Beast in the Jungle tells a love tragedy:The two young English people--John Marcher and May Bartram encounters in London after they first met in Italy ten years ago.Marcher has always had a feeling that one day an awful destiny will fall on him,just as he is to be attacked by a beast crouching in the jungle.So he requests May to watch with him.Out of love,May promises
Williams, Jeremy D; Abt, Grant; Kilding, Andrew E
2010-12-01
The aim of this study was to determine the validity and reliability of a 90-minute soccer performance test: Ball-sport Endurance and Sprint Test (BEAST90). Fifteen healthy male amateur soccer players participated and attended 5 testing sessions over a 10-day period to perform physiologic and soccer-specific assessments. This included familiarization sessions and 2 full trials of the BEAST90, separated by 7 days. The total 90-minute distance, mean percent peak heart rate (HRpeak), and estimated percent peak oxygen uptake of the BEAST90 were 8,097 ± 458 m, 85 ± 5% and 82 ± 14%, respectively. Measures obtained from trial 1 and trial 2 were not significantly different (p > 0.05). Reliability of measures over 90 minutes ranged from 0.9-25.5% (% typical error). The BEAST90 protocol replicated soccer match play in terms of time, movement patterns, physical demands (volume and intensity), distances, and mean and HRpeak values, as well as having an aerobic load similar to that observed during a soccer match. Reproducibility of key physical measures during the BEAST90 were mostly high, suggesting good reliability. The BEAST90 could be used in studies that wish to determine the effects of training or nutritional interventions on prolonged intermittent physical performance.
DEFF Research Database (Denmark)
Lehtonen, Kari K.; Sundelin, Brita; Lang, Thomas;
: Tools for the Assessment of Ecosystem Health, 2009-2011), which is part of the Baltic Sea BONUS+ Programme funded jointly by national funding agencies and FP7 ERA-NET+ of the European Commission. The BEAST project consists of three workpackages (WP) with the following main tasks: WP1- Field studies...... and experiments in selected sub-regions of the Baltic Sea, WP2 - Application and validation of methods in monitoring and assessment in the Baltic Sea, and WP3 - Developing tools for ecosystem health assessment in the Baltic Sea. BEAST research activities are focused in the sub-regions of Gulf of Bothnia, Gulf...... of Finland, Gulf of Riga, Gulf of Gdansk and the Belt Sea, most of which are characterised by scarce data on biological effects of hazardous substances. The data acquired will be combined with previous data (e.g. national monitoring activities, case studies, EU BEEP project) to reach the goals of WP2 and WP3...
Energy Technology Data Exchange (ETDEWEB)
Secher, Bernard [French Atomic Energy Commission (CEA), Nuclear Energy Division (DEN) (France); CEA Saclay DM2S/SFME/LGLS, Bat. 454, F-91191 Gif-sur-Yvette Cedex (France)], E-mail: bsecher@cea.fr; Belliard, Michel [French Atomic Energy Commission (CEA), Nuclear Energy Division (DEN) (France); CEA Cadarache DER/SSTH/LMDL, Bat. 238, F-13108 Saint-Paul-lez-Durance Cedex (France); Calvin, Christophe [French Atomic Energy Commission (CEA), Nuclear Energy Division (DEN) (France); CEA Saclay DM2S/SERMA/LLPR, Bat. 470, F-91191 Gif-sur-Yvette Cedex (France)
2009-01-15
This paper describes a tool called 'Numerical Platon' developed by the French Atomic Energy Commission (CEA). It provides a freely available (GNU LGPL license) interface for coupling scientific computing applications to various freeware linear solver libraries (essentially PETSc, SuperLU and HyPre), together with some proprietary CEA solvers, for high-performance computers that may be used in industrial software written in various programming languages. This tool was developed as part of considerable efforts by the CEA Nuclear Energy Division in the past years to promote massively parallel software and on-shelf parallel tools to help develop new generation simulation codes. After the presentation of the package architecture and the available algorithms, we show examples of how Numerical Platon is used in sequential and parallel CEA codes. Comparing with in-house solvers, the gain in terms of increases in computation capacities or in terms of parallel performances is notable, without considerable extra development cost.
Heuristics of the Platonic Polyhedra for the high Restrictions Reality Research
Directory of Open Access Journals (Sweden)
José Ricardo Díaz Caballero
2013-02-01
Full Text Available In the present work, are exposed concepts, principles and procedures that make up a theory for theheuristical geometrical interpretation of high restrictions reality, based on a thesis where the PlatonicPolyhedra are carriers of a content with a high heuristic potential for the theoretical interpretation ofreality, particularly the high restriction systems , for example the Periodic Table of Chemical Elements,the System of Notes and Tempered Musical Scales and the Universal Genetic Code.
Elementary abelian regular coverings of Platonic maps, Case I: ordinary representations
Jones, Gareth A
2012-01-01
We classify the orientably regular maps which are elementary abelian regular branched coverings of Platonic maps M, in the case where the covering group and the rotation group G of M have coprime orders. The method involves studying the representations of G on certain homology groups of the sphere, punctured at the branch-points. We give a complete classification for branching over faces (or, dually, vertices) of M, and outline how the method extends to other branching patterns.
Directory of Open Access Journals (Sweden)
Sonja Weiss
2009-07-01
Full Text Available The article presents the leading Platonic doctrines of the embodied soul, examining the relation between their Orphic and Pythagorean roots and Plotinus’ correction of the Neo-Pythagorean pessimism on the one hand, and Gnostic solutions of the problem on the other. The analysis of certain Gnostic passages clearly shows that, in spite of Plotinus’ anti-Gnostic polemic, some of the ideas proposed by the philosopher as an alternative to his opponents’ pessimism are also present in the Gnostic descriptions of the emanation from the first Principle and the multiplication of the Eons. The article focuses on the passages which, avoiding an ethical valuation of the generation and multiplication process, limit the concept of sin to the human domain, where it belongs in Plotinus’ view as well. Moreover, the article endeavours to throw light on some of the most controversial themes, which were to remain irreconcilable despite a number of tenets shared by both sides.
A Persistent Back-End for the ATLAS TDAQ On-line Information Service (P-BEAST)
Sicoe, A; The ATLAS collaboration; Kolos, S; Magnoni, L; Soloviev, I
2011-01-01
This paper describes P-BEAST, a highly scalable, highly available and durable system for archiving monitoring information of the trigger and data acquisition (TDAQ) system of the ATLAS experiment at CERN. Currently this consists of 20,000 applications running on 2,400 interconnected computers but it is foreseen to grow further in the near future. P-BEAST stores considerable amounts of monitoring information which would otherwise be lost. Making this data accessible, facilitates long term analysis and faster debugging. The novelty of this research consists of using a modern key-value storage technology (Cassandra) to satisfy the massive time series data rates, flexibility and scalability requirements entailed by the project. The loose schema allows the stored data to evolve seamlessly with the information flowing within the Information Service. An architectural overview of P-BEAST is presented alongside a discussion about the technologies considered as candidates for storing the data. The arguments which ultim...
Following Hegel’s Sovereign Beast: An Excursus on the Right of Heroes
Directory of Open Access Journals (Sweden)
Joshua Ben David Nichols
2013-01-01
Full Text Available In The Beast and the Sovereign, Derrida addresses an association that is as paradoxical as it is common. On the one hand, it seems as if the sovereign is, or at least should be, the furthest from the beast. And yet, as soon as we consult the various archives of political mythology––myth, theology, philosophy, art, etc.––we find them together, inseparable despite their distance. The seminar itself is a continuation of his previous explorations of the host concepts and figures that populate the political and philosophical history of sovereignty. The course takes him through a series of texts that stretches from Plato, Machiavelli, Hobbes and Rousseau, to Freud, Heidegger, Lacan and Schmitt, among others, but his engagement with Hegel is limited. The few times that Hegel’s name does appear, it is almost exclusively a reference or aside within other more substantial engagements (Lacan and Heidegger, in particular. This absence is at least somewhat curious given the extent of Derrida’s previous engagements with Hegel’s corpus. I am not suggesting that this absence constitutes some essential oversight; rather, it is an opportunity to set out on an excursion from the course of The Beast and the Sovereign without leaving its territory. After all, Hegel also has an account of the origins of law. He, too, has a character that is set apart by his (almost animal quality. This figure arrives on stage before history begins. His role––and indeed his “right”––is to found the most basic elements of the state. We are told that his “right” is absolute. He is no Lord. He is not driven by a desire for the recognition of the other. However, who confers this “absolute” right? If his actions are not bound by any measure or proportion, how do we distinguish between the hero and the criminal?
Deconstructing the Leviathan: Derrida’s The Beast and the Sovereign
Directory of Open Access Journals (Sweden)
Jacques de Ville
2012-12-01
Full Text Available Derrida’s The Beast & the Sovereign, volume I, explores the contradictory appearance of animals in political discourse. Sometimes, as he points out, political man and the sovereign state appear in the form of an animal and, at other times, as superior to animals of which he is the master. In session two of the Seminar, the main focus of this essay, Derrida explores the ‘origin’ of this contradictory logic inter alia with reference to animal fables which he contends draw on unconscious forces in their invocation of images. They pretend to make known something that cannot be the object of knowledge. In the same vein, Derrida shows how Hobbes’s Leviathan and sovereignty itself are constructed and maintained through an uncanny fear, a fear not in the first place of one’s fellow man, but of the wolf within the self, i.e., the drive to self-destruction. It is the repression of this wolf, Derrida suggests, which leads to the further contradictory logic (in Hobbes of excluding both beast and God from the covenant whilst maintaining God as the model of sovereignty. God, in other words, ‘is’ the beast repressed and can therefore hardly serve as the foundation of sovereignty. The self, and ultimately sovereignty, it can be said in view of Derrida’s analysis, is never purely present to itself but instead arrives at itself by way of the ‘binding’ of unconscious forces. Sovereignty in this way ultimately shows itself to be divisible.
El Triangulo de Platon y El Factor Gnomonico: Una aplicacion a los oraculos de Herodoto
Perez-Enriquez, Raul
2013-01-01
A modification to the gnomonic factor using the concept of triangle of Plato is presented. With the aid of the platonic gnomonic factor (fgp) as we called it, we find that the oracles mentioned by Herodotus in his History, Dodona in Greece and Ammon in Oasis Siwa, Libya, were placed there because the noon shadow of Sun of a gnomon formed, back in 2500BC, the triangle of Plato the former, and the Egyptian sacred triangle the latter. This means that both concepts were known by Egyptians form Th...
El Triangulo de Platon y El Factor Gnomonico: Una aplicacion a los oraculos de Herodoto
Perez-Enriquez, Raul
2013-01-01
A modification to the gnomonic factor using the concept of triangle of Plato is presented. With the aid of the platonic gnomonic factor (fgp) as we called it, we find that the oracles mentioned by Herodotus in his History, Dodona in Greece and Ammon in Oasis Siwa, Libya, were placed there because the noon shadow of Sun of a gnomon formed, back in 2500BC, the triangle of Plato the former, and the Egyptian sacred triangle the latter. This means that both concepts were known by Egyptians form Thebes long before they were formalized by the Greeks. The right angled triangle concept is an idealization, as said by D. Magdolen, of an astronomical observation; i. e. it is the shadow cast by a gnomon. ----- Se presenta una modificacion al factor gnomonico usando el concepto de triangulo de Platon. Con la ayuda de lo que llamamos factor gnomonico platonico (fgp) nosotros encontramos que los oraculos mencionados por Herodoto en su Historia, Dodona en Grecia, y Ammon en el Oasis Siwa, Libia, fueron ubicados ahi porque, ha...
Khudaverdian, H M
2016-01-01
We notice that one of the Diophantine equations, $knm=2kn+2km+2nm$, arising in the universality originated Diophantine classification of simple Lie algebras, has interesting interpretations for two different sets of signs of variables. In both cases it describes "regular polyhedrons" with $k$ edges in each vertex, $n$ edges of each face, with total number of edges $|m|$, and Euler characteristics $\\chi=\\pm 2$. In the case of negative $m$ this equation corresponds to $\\chi=2$ and describes true regular polyhedrons, Platonic solids. The case with positive $m$ corresponds to Euler characteristic $\\chi=-2$ and describes the so called equivelar maps (charts) on the surface of genus $2$. In the former case there are two routes from Platonic solids to simple Lie algebras - abovementioned Diophantine classification and McKay correspondence. We compare them for all solutions of this type, and find coincidence in the case of icosahedron (dodecahedron), corresponding to $E_8$ algebra. In the case of positive $k$, $n$ an...
Labudde, D; Leitner, D; Krüger, M; Oschkinat, H
2003-01-01
The algorithm PLATON is able to assign sets of chemical shifts derived from a single residue to amino acid types with its secondary structure (amino acid species). A subsequent ranking procedure using optionally two different penalty functions yields predictions for possible amino acid species for the given set of chemical shifts. This was demonstrated in the case of the alpha-spectrin SH3 domain and applied to 9 further protein data sets taken from the BioMagRes database. A database consisting of reference chemical shift patterns (reference CSPs) was generated from assigned chemical shifts of proteins with known 3D-structure. This reference CSP database is used in our approach for extracting distributions of amino acid types with their most likely secondary structure elements (namely alpha-helix, beta-sheet, and coil) for single amino acids by comparison with query CSPs. Results obtained for the 10 investigated proteins indicates that the percentage of correct amino acid species in the first three positions in the ranking list, ranges from 71.4% to 93.2% for the more favorable penalty function. Where only the top result of the ranking list for these 10 proteins is considered, 36.5% to 83.1% of the amino acid species are correctly predicted. The main advantage of our approach, over other methods that rely on average chemical shift values is the ability to increase database content by incorporating newly derived CSPs, and therefore to improve PLATON's performance over time.
Losh, Susan Carol; Nzekwe, Brandon
2011-05-01
Faculty have long expressed concern about pseudoscience belief among students. Most US research on such beliefs examines evolution-creation issues among liberal arts students, the general public, and occasionally science educators. Because of their future influence on youth, we examined basic science knowledge and several pseudoscience beliefs among 540 female and 123 male upperclass preservice teachers, comparing them with representative samples of comparably educated American adults. Future teachers resembled national adults on basic science knowledge. Their scores on evolution; creationism; intelligent design; fantastic beasts; magic; and extraterrestrials indices depended on the topic. Exempting science education, preservice teachers rejected evolution, accepting Biblical creation and intelligent design accounts. Sizable minorities "awaited more evidence" about fantastic beasts, magic, or extraterrestrials. Although gender, disciplinary major, grade point average, science knowledge, and two religiosity measures related to beliefs about evolution-creation, these factors were generally unassociated with the other indices. The findings suggest more training is needed for preservice educators in the critical evaluation of material evidence. We also discuss the judicious use of pseudoscience beliefs in such training.
Do missing data influence the accuracy of divergence-time estimation with BEAST?
Zheng, Yuchi; Wiens, John J
2015-04-01
Time-calibrated phylogenies have become essential to evolutionary biology. A recurrent and unresolved question for dating analyses is whether genes with missing data cells should be included or excluded. This issue is particularly unclear for the most widely used dating method, the uncorrelated lognormal approach implemented in BEAST. Here, we test the robustness of this method to missing data. We compare divergence-time estimates from a nearly complete dataset (20 nuclear genes for 32 species of squamate reptiles) to those from subsampled matrices, including those with 5 or 2 complete loci only and those with 5 or 8 incomplete loci added. In general, missing data had little impact on estimated dates (mean error of ∼5Myr per node or less, given an overall age of ∼220Myr in squamates), even when 80% of sampled genes had 75% missing data. Mean errors were somewhat higher when all genes were 75% incomplete (∼17Myr). However, errors increased dramatically when only 2 of 9 fossil calibration points were included (∼40Myr), regardless of missing data. Overall, missing data (and even numbers of genes sampled) may have only minor impacts on the accuracy of divergence dating with BEAST, relative to the dramatic effects of fossil calibrations.
Spenser’s Blatant Beast: The Thousand Tongues of Elizabethan Religious Polemic
Directory of Open Access Journals (Sweden)
Christopher A. Hill
2017-04-01
Full Text Available This article addresses the final two books of the 1596 edition of Spenser’s Faerie Queene, in which there arises a formidable adversary: the Blatant Beast. This monster, whose presence dominates the end of Book Five and a substantial portion of Book Six, represents the worst excesses of caustic and satirical rhetoric as manifest in the theological and ecclesiastical pamphlet disputes that erupted after Fields and Wilcox’s 1572 Admonition to Parliament. That these disputes were about serious and far-reaching matters is undeniable; it is also undeniable that the means by which these disputes were waged, especially in notorious cases like those of Martin Marprelate, caused significant intellectual, rhetorical, and religious anxiety among combatants and observers alike. Spenser’s heavily allegorized presentation of polemic and pamphleteering in the figure of the Blatant Beast—and the travails of the Knights of Justice and of Courtesy in bringing the beast to heel—can illustrate for students the full extent of that anxiety in Reformation England, as well as articulate Spenser’s call for the timely application of “well guided speech” as the solution to these reckless disputes.
Relativistic spherical plasma waves
Bulanov, S. S.; Maksimchuk, A.; Schroeder, C. B.; Zhidkov, A. G.; Esarey, E.; Leemans, W. P.
2012-02-01
Tightly focused laser pulses that diverge or converge in underdense plasma can generate wake waves, having local structures that are spherical waves. Here we study theoretically and numerically relativistic spherical wake waves and their properties, including wave breaking.
Rainer Knab, Platons Siebter Brief. Einleitung, Text, Übersetzung, Kommentar
Brisson, Luc
2016-01-01
Cette traduction commentée de la septième Lettre attribuée à Platon est un objet étrange. On y trouve imprimé le texte édité par Burnet en 1905, mais on ne trouve rien sur l’édition de Souilhé aux Belles Lettres en 1926 ni celle de J. Moore-Blunt chez Teubner en 1985. De surcroît, la bibliographie qui clôt le volume fait montre d’incroyables faiblesses en ce qui concerne les traductions et les commentaires utilisés. Dans l’introduction, R. Knab admet, mais sans apporter d’arguments nouveaux,...
Efficient methods for solving discrete topology design problems in the PLATO-N project
DEFF Research Database (Denmark)
Canh, Nam Nguyen; Stolpe, Mathias
This paper considers the general multiple load structural topology design problems in the framework of the PLATO-N project. The problems involve a large number of discrete design variables and were modeled as a non-convex mixed 0–1 program. For the class of problems considered, a global...... optimization method based on the branch-and-cut concept was developed and implemented. In the method a large number of continuous relaxations were solved. We also present an algorithm for generating cuts to strengthen the quality of the relaxations. Several heuristics were also investigated to obtain efficient...... algorithms. The branch and cut method is used to solve benchmark examples which can be used to validate other methods and heuristics....
Queen Christina’s esoteric interests as a background to her Platonic Academies
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Susanna Åkerman
2008-01-01
Full Text Available In 1681 the blind quietist, Francois Malaval, stated that Queen Christina of Sweden late in life had ‘given up’ [Hermes] Trismegistos and the Platonists, in favour of the Church fathers. The statement does not explain what role the Church fathers were to play in her last years, but it does show that Christina really had been interested in the rather elitist and esoteric doctrine of Hermetic Platonic Christianity. In this article the author looks at her library to show the depth of this Hermetic involvement. Her interest serves as a background to her life as ex-queen in Italy after her famous abdication from the Swedish throne in 1654, when she was 27 years old.
Structure and binding in crystals of cage-like molecules: hexamine and platonic hydrocarbons
Berland, Kristian; 10.1063/1.3366652
2010-01-01
In this paper, we show that first-principle calculations using a van der Waals density functional (vdW-DF), [Phys. Rev. Lett. $\\mathbf{92}$, 246401 (2004)] permits determination of molecular crystal structure. We study the crystal structures of hexamine and the platonic hydrocarbons (cubane and dodecahedrane). The calculated lattice parameters and cohesion energy agree well with experiments. Further, we examine the asymptotic accounts of the van der Waals forces by comparing full vdW-DF with asymptotic atom-based pair potentials extracted from vdW-DF. The character of the binding differ in the two cases, with vdW-DF giving a significant enhancement at intermediate and relevant binding separations. We analyze consequences of this result for methods such as DFT-D, and question DFT-D's transferability over the full range of separations.
Hermeneutics and the philosophy of medicine: Hans-Georg Gadamer's platonic metaphor.
Lingiardi, V; Grieco, A
1999-09-01
Taking as our starting point Plato's metaphor of the doctor as philosopher we reflect on some aspects of the epistemological status of medicine. The framework to this paper is the hermeneutics of Hans-Georg Gadamer which shows the paradoxical nature of Western medicine in choosing the body-object as its investigative starting point, while in actual fact dealing with subjects. Gadamer proposes a model of medicine as the art of understanding and dialogue, which is capable of bringing together its various constituent parts, i.e. knowledge, knowing how to do and knowing how to be, in medical practice and in the physician's training. The paper concludes with a brief discussion of the dyadic figure of the physician as Platonic "master of the living totality" and wounded healer, capable of activating the patient's self-healing capacity.
The pharmacist and the Medicare Modernization Act: beauty and the beast?
Hutchison, Lisa C
2007-01-01
Pharmacists across the nation envisioned great benefits from a nationally funded prescription drug insurance program to aid our senior and disabled patients. The Medicare Modernization Act of 2003 (MMA), containing this prescription drug provision, reminds me of a wild animal that you begin to see in the distance moving toward you. You try to find higher ground to give a defensive advantage. It slowly comes into view and then it finally arrives with loud roaring and vicious threats-ugly and wonderful at the same time. When the animal's attack comes, you engage all your defensive and offensive moves. If you survive, you become stronger and wiser before the next beast appears. In the same way, the pharmacist's vision of improved access to care has been realized, although it is occurring through much pain for our beautiful pharmacy profession.
Age of the Harrison Street Beast: Electron paramagnetic resonance spectra from tooth enamel
Energy Technology Data Exchange (ETDEWEB)
Weeks, R.A. [Vanderbilt Univ., Nashville, TN (United States). Dept. of Mechanical Engineering; Elam, J.M.; Davenport, C. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Anthropology; Bogard, J.S. [Oak Ridge National Lab., TN (United States). Life Sciences Div.
1998-04-01
Workers doing road reconstruction in 1993 in Fort Wayne, Indiana, uncovered remains of a large skeleton and contacted archaeologists for assessment prior to continuing work. The archaeologists excavated the remains which were located in a 19-cm thick layer of blue glay, a pedological deposit which forms from wet, anaerobic environments associated with bogs. This glay layer was located some 2 meters below the current ground level (Davenport 1996). In this paper, the authors present the results of an EPR analysis of tooth enamel (biogenic hydroxyapatite) from the Harrison Street Beast. The objectives of this study are: (1) determine an age for the specimen through EPR analysis of molar tooth enamel; (2) resolve and identify the radiation sensitive EPR spectral components; and (3) develop a provisional model for the creation of radiation-sensitive components in the EPR spectra.
Towards the genetic basis of cerebral venous thrombosis—the BEAST Consortium: a study protocol
Cotlarciuc, Ioana; Marjot, Thomas; Khan, Muhammad S; Hiltunen, Sini; Haapaniemi, Elena; Metso, Tiina M; Putaala, Jukka; Zuurbier, Susanna M; Brouwer, Matthijs C; Passamonti, Serena M; Bucciarelli, Paolo; Pappalardo, Emanuela; Patel, Tasmin; Costa, Paolo; Colombi, Marina; Canhão, Patrícia; Tkach, Aleksander; Santacroce, Rosa; Margaglione, Maurizio; Favuzzi, Giovanni; Grandone, Elvira; Colaizzo, Donatella; Spengos, Kostas; Arauz, Antonio; Hodge, Amanda; Ditta, Reina; Debette, Stephanie; Zedde, Marialuisa; Pare, Guillaume; Ferro, José M; Thijs, Vincent; Pezzini, Alessandro; Majersik, Jennifer J; Martinelli, Ida; Coutinho, Jonathan M; Tatlisumak, Turgut; Sharma, Pankaj
2016-01-01
Introduction Cerebral venous thrombosis (CVT) is a rare cerebrovascular condition accounting for <1% of all stroke cases and mainly affects young adults. Its genetic aetiology is not clearly elucidated. Methods and analysis To better understand the genetic basis of CVT, we have established an international biobank of CVT cases, Biorepository to Establish the Aetiology of Sinovenous Thrombosis (BEAST) which aims to recruit highly phenotyped cases initially of European descent and later from other populations. To date we have recruited 745 CVT cases from 12 research centres. As an initial step, the consortium plans to undertake a genome-wide association analysis of CVT using the Illumina Infinium HumanCoreExome BeadChip to assess the association and impact of common and low-frequency genetic variants on CVT risk by using a case–control study design. Replication will be performed to confirm putative findings. Furthermore, we aim to identify interactions of genetic variants with several environmental and comorbidity factors which will likely contribute to improve the understanding of the biological mechanisms underlying this complex disease. Ethics and dissemination BEAST meets all ethical standards set by local institutional review boards for each of the participating sites. The research outcomes will be published in international peer-reviewed open-access journals with high impact and visibility. The results will be presented at national and international meetings to highlight the contributions into improving the understanding of the mechanisms underlying this uncommon but important disease. This international DNA repository will become an important resource for investigators in the field of haematological and vascular disorders. PMID:27881526
Institute of Scientific and Technical Information of China (English)
2011-01-01
OVER 19, ooospecies of animal and plant are in danger of extinction, up from just over 11, ooo in 2000, according to the latest ＂Red List of Threatened Species＂ from the International Union for Conservation of Nature （IUCN）. 2 Of those evaluated, nearly one-third are considered ＂threatened＂ （critically endangered, endangered or vulnerable ）.
Directory of Open Access Journals (Sweden)
Maria Chiara Pievatolo
2011-05-01
Full Text Available Secondo alcune fonti antiche il sofista Protagora, ormai anziano, fu accusato, come Socrate, di empietà e trovò la morte lasciando Atene, forse per sfuggire al processo o forse perché bandito dalla città. Contro questa tradizione sembra militare la testimonianza di Platone, secondo la quale, almeno in apparenza, Protagora, a differenza di altri intellettuali, non si [...
Directory of Open Access Journals (Sweden)
Bonnie Cross
2014-12-01
Full Text Available The Beast Folk in H.G. Wells’ The Island of Dr. Moreau (1896 use language to raise the fear of human degeneration by revealing the inner animal within humanity. Moreau re-creates the physical mechanisms for speech such as the larynx, but is also able to manipulate the brain to create the necessary structures for speech, previously unique to the human brain, into nonhumans. Applying Darwin’s theory that the continued use of speech led to the physical and mental changes of humans, the argument can be made that ceasing to use speech would weaken these structures of speech. After Moreau’s death, the Beast Folk no longer heed the Law and stop speaking, becoming more animalistic through their silence. Prendick also loses his language after the death of Moreau and Montgomery and begins to struggle differentiating the Beast Folk from humans. The Island of Dr. Moreau addresses the Victorian anxiety regarding the use of language as a definite boundary between humans and animals by suggesting that language fails to keep the inner animal of humanity at bay. Neuroscience has linked animal and human sounds revealing the mechanisms responsible for the production and understanding of language creating a new paradigm to explore.
On structuralism, and the poststructuralistic condition in Deleuze, inverter of Platonism
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Manuel Altamirano
2016-11-01
Full Text Available Focusing on Gilles Deleuze´s second stage of thought, specially his work of inversion of Platonism, we´ll show why the concept of structure is so important, as well as its conditions and functioning, and how this characterization has an impact on central concepts such as identity or difference. That way we´ll understand the idealistic character of Deleuze´s philosophy, thus a different kind of Plato´s idealism. We´ll take into consideration, also, the realm of the “problematic”, and the “ideal game”. We´ll evaluate the six necessary criteria of what Deleuze calls an “Idea”. Given the conditions we´ll establish trough this revision, we´ll be able to conclude that Deleuze overtakes structuralism and embraces poststructuralism. This last affirmation will be argued trough a comparison between Delezue´s poststructuralism and the basics of more classical, Lévi-Straus´s structuralism
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Mikhailova N. V.
2015-01-01
Full Text Available The author of the work proposes a philosophical and methodological interpretation of the mathematical objects, using the system triad of the main directions of substantiation of mathematics: the formalism of Hilbert, Brouwer’s intuitionism and Godel’s Platonism. The need for these directions in the concept of substantiation of mathematics from the point of view of the current state of the philosophy of mathematics is shown on the mathematical examples. The philosophical and methodological analysis of objects of mathematics has never been unambiguous, therefore in this paper the results of studies of philosophers, logicians and mathematicians, in which the problem of substantiation is explicated in the context of trends in the development of mathematics, are used. Their professional view on philosophical characteristics of the objects of mathematics contributes to the identification of the unity of all mathematical knowledge maintaining the initial mathematical base of knowledge and revealing new ways of integrating the directions of substantiation in the philosophy of mathematics. The practical problem of substantiation of mathematics is realized through the elaboration of metatheoretical knowledge under the paradigm shift in the philosophy of mathematics to the productive direction from analysis to synthesis.
Platonism, cartesianism and Hegel’s thought in the Matrix Trilogy
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Milidrag Predrag
2013-01-01
Full Text Available In this article I will try to interpret changes in Neo, the main character in The Matrix Trilogy, against the background of the ideas of Plato and Descartes, as well as Hegel’s from his Philosophy of History and The Phenomenology of Spirit. Although “philosophical” The Matrix Trilogy is not long-winded and boring film: instead of talking endlessly, the characters are working ceaselessly, and that work is changing them. Contrary to widespread opinion, this interpretation does not find the presence of Descartes’ hyperbolic doubt in the first part of trilogy, but first film sees as a pure Platonism. Nevertheless, there are the Cartesian motifs (e.g. dualism, freeing mind from preconceived opinions, acquiring different habits of belief. The result of the first film is the position of Hegelian unhappy consciousness. This is just a preparation for the key moment of whole Trilogy that is the dialogue between Neo and Architect. Neo’s decision to chose to save Trinity is interpreted in Hegel’s terms of the infinite right of the subject to satisfy himself in his activity and work; because of that, this, sixth Neo is new. After showing the differences in the objectives of Neo and Agent Smith, and transformations of the objectives of humans, the third part of the article analyzes the very end of the Matrix Revolutions, using Marx’s ideas, with some references to Plato and Nietzsche.
Expel poetry from life and society, exile poets. Modern interpretations of the Platonic postulate
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Krystyna Bartol
2012-01-01
Full Text Available This article is a critical review of the most important modern interpretations of the Platonic postulate of expelling poets from the polis, formulated in two works of the thinker, the Republic and the Laws. The reflections presented in the article focus on two fundamental questions, namely the reasons behind Plato’s refusal to allow poets into his ideal state and, secondly, the aim he was going to attain by expelling artists from the community of citizens. To try to explain the reasons behind these statements, so embarrassing to present-day readers of Plato, involves considerations of Plato’s concept of the nature of poetry (art as flawed, defective and secondary reflection of the sensual world, as well as of ethical questions (art as a perfidious tool to facilitate malevolent designs towards human characters. Any investigation as to the intentions of the philosophers that preceded the formulation of the postulate concentrates thus inevitably on his vision of utopian realism. It further aims to provide sufficient arguments that Plato, oscillating in his presentation between authoritarian diagnosis and protreptic provocation, makes recipients redefine the mutual relationship between literature and philosophy.
Une histoire de la lumière de Platon au photon
Maitte, Bernard
2015-01-01
De la sensation commune à la compréhension scientifique, nos idées sur la nature et les propriétés de la lumière ont connu un long cheminement depuis les théories de Platon jusqu'à la maîtrise du photon. L'Antiquité, la civilisation arabo-islamique, la Renaissance européenne et sa révolution scientifique, puis la science classique du me siècle, les avancées modernes enfin, autant de moments dans la riche histoire de nos connaissances sur la lumière. Ce livre décrit l'élaboration tourmentée des idées, tant philosophiques que scientifiques, qui ont scandé cette histoire, tirant profit des succès comme des échecs, des efforts comme des renoncements. "En regardant d'un oeil critique l'histoire de la lumière, nous pourrons accéder à notre tour à cette logique savoureuse et amère que l'on appelle Science." La première édition de ce livre, ici considérablement augmentée, a obtenu le prix Jean-Rostand du meilleur ouvrage de vulgarisation scientifique.
Ultra-large supramolecular coordination cages composed of endohedral Archimedean and Platonic bodies
Byrne, Kevin; Zubair, Muhammad; Zhu, Nianyong; Zhou, Xiao-Ping; Fox, Daniel S.; Zhang, Hongzhou; Twamley, Brendan; Lennox, Matthew J.; Düren, Tina; Schmitt, Wolfgang
2017-05-01
Pioneered by Lehn, Cram, Peterson and Breslow, supramolecular chemistry concepts have evolved providing fundamental knowledge of the relationships between the structures and reactivities of organized molecules. A particular fascinating class of metallo-supramolecular molecules are hollow coordination cages that provide cavities of molecular dimensions promoting applications in diverse areas including catalysis, enzyme mimetics and material science. Here we report the synthesis of coordination cages with exceptional cross-sectional diameters that are composed of multiple sub-cages providing numerous distinctive binding sites through labile coordination solvent molecules. The building principles, involving Archimedean and Platonic bodies, renders these supramolecular keplerates as a class of cages whose composition and topological aspects compare to characteristics of edge-transitive {Cu2} MOFs with A3X4 stoichiometry. The nature of the cavities in these double-shell metal-organic polyhedra and their inner/outer binding sites provide perspectives for post-synthetic functionalizations, separations and catalysis. Transmission electron microscopy studies demonstrate that single molecules are experimentally accessible.
论英国文艺复兴时期的新柏拉图主义图景%Neo-Platonic Variations in Renaissance England
Institute of Scientific and Technical Information of China (English)
潘先利
2012-01-01
Neo-Platonic variations in Renaissance England is a promising arena for further scholarly exploration. A platonic landscape is outlined with explicit British features： John Colet＇s idea in Christian image, Thomas Moore＇s Platonic Utopian train of thought and John Dee＇s Christian-Platonic numerology and magic--all construct a blueprint of Platonic cosmos.%英国文艺复兴时期的新柏拉图主义在当时是一股不可忽略的知性力量，但其形成性研究还是一个学术冷门。主要考证该思潮的本土化变体，尤其聚焦约翰·克里特的基督教理式模型、托马斯·莫尔结合了柏拉图古典社会完美观念和古罗马修辞策略的鸟托邦思想、约翰·迪的基督教一柏拉图式数字命理哲学和神秘主义魔法理论等具有英国风貌的新柏拉图主义宇宙图景。
Relativistic spherical plasma waves
Bulanov, S S; Schroeder, C B; Zhidkov, A G; Esarey, E; Leemans, W P
2011-01-01
Tightly focused laser pulses as they diverge or converge in underdense plasma can generate wake waves, having local structures that are spherical waves. Here we report on theoretical study of relativistic spherical wake waves and their properties, including wave breaking. These waves may be suitable as particle injectors or as flying mirrors that both reflect and focus radiation, enabling unique X-ray sources and nonlinear QED phenomena.
Institute of Scientific and Technical Information of China (English)
王琳; 高敏娜
2014-01-01
The background of Captain Corelli’s Mandolin is based on World War II. When the war provoked on the Greek Is-land, the Greeks fight against the Italian Fascist and live a tough life with their love. This article mainly talks about the essence of the Platonic love revealed in the book. By analyzing the description about homosexuality and heterosexuality in the book, this ar-ticle acclaims the essence of the Platonic love-the noble abstention of lust-based love and the truth, kindness and beauty of love.
Spherical coverage verification
Petkovic, Marko D; Latecki, Longin Jan
2011-01-01
We consider the problem of covering hypersphere by a set of spherical hypercaps. This sort of problem has numerous practical applications such as error correcting codes and reverse k-nearest neighbor problem. Using the reduction of non degenerated concave quadratic programming (QP) problem, we demonstrate that spherical coverage verification is NP hard. We propose a recursive algorithm based on reducing the problem to several lower dimension subproblems. We test the performance of the proposed algorithm on a number of generated constellations. We demonstrate that the proposed algorithm, in spite of its exponential worst-case complexity, is applicable in practice. In contrast, our results indicate that spherical coverage verification using QP solvers that utilize heuristics, due to numerical instability, may produce false positives.
Spherical geodesic mesh generation
Energy Technology Data Exchange (ETDEWEB)
Fung, Jimmy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kenamond, Mark Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Burton, Donald E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Shashkov, Mikhail Jurievich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-02-27
In ALE simulations with moving meshes, mesh topology has a direct influence on feature representation and code robustness. In three-dimensional simulations, modeling spherical volumes and features is particularly challenging for a hydrodynamics code. Calculations on traditional spherical meshes (such as spin meshes) often lead to errors and symmetry breaking. Although the underlying differencing scheme may be modified to rectify this, the differencing scheme may not be accessible. This work documents the use of spherical geodesic meshes to mitigate solution-mesh coupling. These meshes are generated notionally by connecting geodesic surface meshes to produce triangular-prismatic volume meshes. This mesh topology is fundamentally different from traditional mesh topologies and displays superior qualities such as topological symmetry. This work describes the geodesic mesh topology as well as motivating demonstrations with the FLAG hydrocode.
The Spherical Deformation Model
DEFF Research Database (Denmark)
Hobolth, Asgar
2003-01-01
Miller et al. (1994) describe a model for representing spatial objects with no obvious landmarks. Each object is represented by a global translation and a normal deformation of a sphere. The normal deformation is defined via the orthonormal spherical-harmonic basis. In this paper we analyse...... the spherical deformation model in detail and describe how it may be used to summarize the shape of star-shaped three-dimensional objects with few parameters. It is of interest to make statistical inference about the three-dimensional shape parameters from continuous observations of the surface and from...
Directory of Open Access Journals (Sweden)
Mauro Bonazzi
2013-05-01
Full Text Available The chapters dedicated to Parmenides and Plato play a decisive role in the composition strategy of the Adversus Colotem, since this is where Plutarch most clearly defines the background dualist thesis that will help demonstrate that Platonism is superior to Epicurism. By showing Parmenides too as a dualist engaged in distinguishing between the sensible and the intelligible world, Plutarch structures a history of ancient philosophy entirely focused on Plato. These chapters also bear witness of another centre of interest, namely Aristoteles (§ 14, who, despite the criticism he aimed at the theory of ideas, is not completely refuted, but rather used as a possible ally against epicurean materialists, Plutarch’s true bête noire.Les chapitres consacrés à Parménide et Platon jouent un rôle décisif dans la stratégie de composition de l’Adversus Colotem : c’est là en effet que Plutarque définit de la manière la plus claire la thèse dualiste de fond qui va servir à démontrer la supériorité du platonisme sur l’épicurisme. En présentant Parménide lui aussi comme un dualiste occupé à distinguer entre monde sensible et monde intelligible, Plutarque articule une histoire de la philosophie antique entièrement centrée sur Platon. Les chapitres témoignent ensuite d’un autre centre d’intérêt, avec la mention d’Aristote (§ 14, lequel, malgré les critiques qu’il adresse à la théorie des idées, n’est pas complètement réfuté, mais plutôt utilisé comme un allié possible contre les matérialistes épicuriens, la véritable « bête noire » de Plutarque.I capitoli dedicati a Parmenide e Platone giocano un ruolo decisivo nella strategia compositiva dell’Adversus Colotem: è qui infatti che Plutarco delinea nel modo più chiaro la tesi dualistica di fondo che servirà a dimostrare la superiorità del platonismo sull’epicureismo. Presentando anche Parmenide come un dualista, impegnato a distinguere tra mondo
Case study: Beauty and the Beast 3D: benefits of 3D viewing for 2D to 3D conversion
Handy Turner, Tara
2010-02-01
From the earliest stages of the Beauty and the Beast 3D conversion project, the advantages of accurate desk-side 3D viewing was evident. While designing and testing the 2D to 3D conversion process, the engineering team at Walt Disney Animation Studios proposed a 3D viewing configuration that not only allowed artists to "compose" stereoscopic 3D but also improved efficiency by allowing artists to instantly detect which image features were essential to the stereoscopic appeal of a shot and which features had minimal or even negative impact. At a time when few commercial 3D monitors were available and few software packages provided 3D desk-side output, the team designed their own prototype devices and collaborated with vendors to create a "3D composing" workstation. This paper outlines the display technologies explored, final choices made for Beauty and the Beast 3D, wish-lists for future development and a few rules of thumb for composing compelling 2D to 3D conversions.
Spherical distributions : Schoenberg revisited
Steerneman, AGM; van Perlo-ten Kleij, F
2005-01-01
An in-dimensional random vector X is said to have a spherical distribution if and only if its characteristic function is of the form phi(parallel to t parallel to), where t is an element of R-m, parallel to.parallel to denotes the usual Euclidean norm, and phi is a characteristic function on R. A mo
Spherical colloidal photonic crystals.
Zhao, Yuanjin; Shang, Luoran; Cheng, Yao; Gu, Zhongze
2014-12-16
CONSPECTUS: Colloidal photonic crystals (PhCs), periodically arranged monodisperse nanoparticles, have emerged as one of the most promising materials for light manipulation because of their photonic band gaps (PBGs), which affect photons in a manner similar to the effect of semiconductor energy band gaps on electrons. The PBGs arise due to the periodic modulation of the refractive index between the building nanoparticles and the surrounding medium in space with subwavelength period. This leads to light with certain wavelengths or frequencies located in the PBG being prohibited from propagating. Because of this special property, the fabrication and application of colloidal PhCs have attracted increasing interest from researchers. The most simple and economical method for fabrication of colloidal PhCs is the bottom-up approach of nanoparticle self-assembly. Common colloidal PhCs from this approach in nature are gem opals, which are made from the ordered assembly and deposition of spherical silica nanoparticles after years of siliceous sedimentation and compression. Besides naturally occurring opals, a variety of manmade colloidal PhCs with thin film or bulk morphology have also been developed. In principle, because of the effect of Bragg diffraction, these PhC materials show different structural colors when observed from different angles, resulting in brilliant colors and important applications. However, this angle dependence is disadvantageous for the construction of some optical materials and devices in which wide viewing angles are desired. Recently, a series of colloidal PhC materials with spherical macroscopic morphology have been created. Because of their spherical symmetry, the PBGs of spherical colloidal PhCs are independent of rotation under illumination of the surface at a fixed incident angle of the light, broadening the perspective of their applications. Based on droplet templates containing colloidal nanoparticles, these spherical colloidal PhCs can be
L’ORALITÀ A SCUOLA, DA PLATONE AL PORTFOLIO EUROPEO DELLE LINGUE
Directory of Open Access Journals (Sweden)
Alberto A. Sobrero
2010-09-01
Full Text Available L'oralità risulta primaria rispetto alla scrittura sia per quanto riguarda la razza umana (filogenesi sia per quanto riguarda lo sviluppo individuale (ontogenesi, tuttavia essa ha sempre goduto di minor prestigio della scrittura. Nella prima parte di questo articolo sono ricostruiti i diversi momenti in cui questa gerarchia è stata fondata e si è affermata stabilmente: dai contrasti epocali tra Socrate e Platone da una parte e i Sofisti dall'altra all'affermazione della centralità della scrittura da parte di Aristotele e degli aristotelici; fino, poi, all'Illuminismo, in cui l'oralità veniva ormai identificata con l'inciviltà, la rozzezza e l'arretratezza, posizione che in qualche misura permane ancora oggi. Nella seconda parte dell'articolo si ricostruisce il graduale recupero del valore dell'oralità nell'insegnamento linguistico, attraverso un'analisi dei programmi scolastici italiani, dalla Legge Casati del 1859 ai Programmi della scuola media e di quella elementare rispettivamente del 1979 e del 1985, alle più recenti "Indicazioni Moratti e infine alle "Indicazioni Fioroni". In queste ultime si sottolinea la necessità di finalizzare l'insegnamento dell'oralità anche a scopi interculturali più ampi, prioritari nella società attuale, quali il rispetto e la promozione delle differenze linguistiche e culturali, lo sviluppo del plurilinguismo; la centralità e l'autonomia dell'apprendente. Historically, the oral tradition has been more important than writing, both in human history (philogenesis and in individual, personal history (onthogenesis, but it has always had far less prestige. The first part of this paper surveys important moments in the formation and establishment of this hierarchy, starting from the fundamental contrast between the Sophists on the one hand, and Socrates and Plato from the other, to the centrality of Aristotle and Aristotelianism, up to the Age of Enlightenment and the identification between orality
Spherical coordinate descriptions of cylindrical and spherical Bessel beams.
Poletti, M A
2017-03-01
This paper derives a generalized spherical harmonic description of Bessel beams. The spherical harmonic description of the well-known cylindrical Bessel beams is reviewed and a family of spherical Bessel beams are introduced which can provide a number of azimuthal phase variations for a single beam radial amplitude. The results are verified by numerical simulations.
Lee, M. C.; Kendall, J. M., Jr.; Bahrami, P. A.; Wang, T. G.
1986-01-01
Fluid-dynamic and capillary forces can be used to form nearly perfect, very small spherical shells when a liquid that can solidify is passed through an annular die to form an annular jet. Gravity and certain properties of even the most ideal materials, however, can cause slight asymmetries. The primary objective of the present work is the control of this shell formation process in earth laboratories rather than space microgravity, through the development of facilities and methods that minimize the deleterious effects of gravity, aerodynamic drag, and uncontrolled cooling. The spherical shells thus produced can be used in insulation, recyclable filter materials, fire retardants, explosives, heat transport slurries, shock-absorbing armor, and solid rocket motors.
Bregestovski, Piotr
2012-01-01
On May 10th 2010 Platon Grigorevitch Kostyuk sadly left us at the age of 85. He was a talented scientist, a brilliant experimenter, an outstanding organizer of science and an excellent teacher. Platon Kostyuk was born in 1924 in Kiev, Ukraine. He obtained a double education: a graduate of the Kiev University Department of Biology in 1946 and the Kiev Medical Institute in 1949, he became a pioneer in neuroscience, the first in the Soviet Union to use microelectrodes for intracellular recording of electrical signals in neurons. Despite the difficulties for international travel for those living behind the Iron Curtain, he was able to present his work at the International Congress of Physiology in Buenos Aires in 1959 and here met Prof. John Eccles who invited him to work at the University of Canberra in Australia in 1960–1961. This was the start of an outstanding international career, complementing his creative achievements in the Soviet Union. In 1966 P.G. Kostyuk became director of the Bogomoletz Institute of Physiology in Kiev, which he headed for nearly 45 years. Under his direction this Institute became a leading centre for neuroscience, renowned not only in the Soviet Union but also internationally. New directions of research were developed in cell physiology, molecular biophysics and neurophysiology. Several important discoveries were made including the development of a method for intracellular perfusion, evidence for a calcium-dependent conductance in nerve cells and the discovery of new types of ion channels. Elected to the Ukraine Academy of Science in 1969 and Grand Academician of the Soviet Academy of Science in 1974, Kostyuk has also been honoured by many international societies. He is the author of more than 650 articles, 17 monographs and 7 discoveries and was the creator and editor of two scientific journals: "Neurophysiology" and "Neuroscience". The outstanding career and multifaceted activities of Academician Platon Kostyuk form a pyramid of
An Analysis of the Agency and Providence in Platonic, Aristotelian and Avicennan Metaphysics
Directory of Open Access Journals (Sweden)
S. Mahdi Emamijomeh
2014-01-01
Full Text Available The questions as to whether the cosmic order of this world is based on action/agent or not? And if an agent is involved and the world and what it contains have to be seen as action, could we declare the cosmic order a providential order? are among the problems which have always occupied the mind of philosophers. Reading through Platonic corpse leads us to the conclusion that he has founded his metaphysics upon the very idea of world of ideas. According to his works and words, Plato is a proponent of the theory of ideas. As a matter of fact, Plato's metaphysics lies in the theory of ideas. Plato illustrates the general makeup of the world of ideas and the way sensible objects stand in relation with the beings dwelling in the latter world by the well-known cave allegory in the seventh book of Republic. In his view, whatever we find around ourselves not only are not authentic realities but rather they are merely shadows of the truth. Every phenomenon has an essence or reality which is known as its form. The idea of Good overshadows the other ideas insofar as these latter ideas or forms are seen as the effects of the former. It seems we can take God, the One, Absolute Good, Absolute Beauty and Good in itself as expressions of the same reality which Plato has used in different contexts through his works. Along these terms some other notions have also been brought up like intellect, divine intellect, Demiurge, ideas and the particulars of material world. By explaining Plato's taking of these notions and terms, we believe, one can discover Platonic ontological system. In Republic, Plato argues that God is the creator of ideal bed and all other things, and he is the creator of intelligible entities (ideas. The One or reality as a whole not only contains ideas but the spirit too. The One is the final principle and the source of ideas and is beyond all human attributes. Having said these, it is not clear how reason gets itself related to the
An Analysis of the Agency and Providence in Platonic, Aristotelian and Avicennan Metaphysics
Directory of Open Access Journals (Sweden)
Vahideh Hadad
2013-12-01
Full Text Available The questions as to whether the cosmic order of this world is based on action/agent or not? And if an agent is involved and the world and what it contains have to be seen as action, could we declare the cosmic order a providential order? are among the problems which have always occupied the mind of philosophers. Reading through Platonic corpse leads us to the conclusion that he has founded his metaphysics upon the very idea of world of ideas. According to his works and words, Plato is a proponent of the theory of ideas. As a matter of fact, Plato's metaphysics lies in the theory of ideas. Plato illustrates the general makeup of the world of ideas and the way sensible objects stand in relation with the beings dwelling in the latter world by the well-known cave allegory in the seventh book of Republic. In his view, whatever we find around ourselves not only are not authentic realities but rather they are merely shadows of the truth. Every phenomenon has an essence or reality which is known as its form. The idea of Good overshadows the other ideas insofar as these latter ideas or forms are seen as the effects of the former. It seems we can take God, the One, Absolute Good, Absolute Beauty and Good in itself as expressions of the same reality which Plato has used in different contexts through his works. Along these terms some other notions have also been brought up like intellect, divine intellect, Demiurge, ideas and the particulars of material world. By explaining Plato's taking of these notions and terms, we believe, one can discover Platonic ontological system. In Republic, Plato argues that God is the creator of ideal bed and all other things, and he is the creator of intelligible entities (ideas. The One or reality as a whole not only contains ideas but the spirit too. The One is the final principle and the source of ideas and is beyond all human attributes. Having said these, it is not clear how reason gets itself related to the
Denton, Michael J; Marshall, Craig J; Legge, Michael
2002-12-07
Before the Darwinian revolution many biologists considered organic forms to be determined by natural law like atoms or crystals and therefore necessary, intrinsic and immutable features of the world order, which will occur throughout the cosmos wherever there is life. The search for the natural determinants of organic form-the celebrated "Laws of Form"-was seen as one of the major tasks of biology. After Darwin, this Platonic conception of form was abandoned and natural selection, not natural law, was increasingly seen to be the main, if not the exclusive, determinant of organic form. However, in the case of one class of very important organic forms-the basic protein folds-advances in protein chemistry since the early 1970s have revealed that they represent a finite set of natural forms, determined by a number of generative constructional rules, like those which govern the formation of atoms or crystals, in which functional adaptations are clearly secondary modifications of primary "givens of physics." The folds are evidently determined by natural law, not natural selection, and are "lawful forms" in the Platonic and pre-Darwinian sense of the word, which are bound to occur everywhere in the universe where the same 20 amino acids are used for their construction. We argue that this is a major discovery which has many important implications regarding the origin of proteins, the origin of life and the fundamental nature of organic form. We speculate that it is unlikely that the folds will prove to be the only case in nature where a set of complex organic forms is determined by natural law, and suggest that natural law may have played a far greater role in the origin and evolution of life than is currently assumed.
Georgiev, G. H.; Dinkova, C. L.
2013-10-01
Long spirals in the Euclidean plane have been introduced by A. Kurnosenko five years ago. Using a natural map of the shape sphere into the extended Gaussian plane we study spherical curves that are pre-images of plane long spirals. Loxodromes and spherical spiral antennas are typical examples of such spherical long spirals. The set of all planar spirals leaves invariant under an arbitrary similarity transformation. This set is divided in two disjoint classes by A. Kirnosenko. The first class is consist of the so-called short spirals which are widely used in geometric modeling. The second class of planar long spirals contains well-known logarithmic spiral and Archimedean spirals which have many applications in mathematics, astrophysics and industry. The notion of simplicial shape space is due to D. Kendall. The most popular simplicial shape space of order (2,3) is the set of equivalence classes of similar triangles in the plane. The sphere of radius 1/2 centered at the origin can be considered as a model of this quotient space, so-called the shape sphere. F. Bookstein and J. Lester showed that the one-point extension of the Euclidean plane, so-called the extended Gaussian plane, is another model of the same simplicial shape space. The present paper gives a description of long spirals on the shape sphere by the use a natural conformal mapping between two models. First, we examine long spirals in the extended Gaussian plane. After that, we describe some differential geometric properties of the shape sphere. Finally, we discuss parameterizations of long spirals on the shape sphere.
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M. A. Navascués
2013-01-01
Full Text Available This paper tackles the construction of fractal maps on the unit sphere. The functions defined are a generalization of the classical spherical harmonics. The methodology used involves an iterated function system and a linear and bounded operator of functions on the sphere. For a suitable choice of the coefficients of the system, one obtains classical maps on the sphere. The different values of the system parameters provide Bessel sequences, frames, and Riesz fractal bases for the Lebesgue space of the square integrable functions on the sphere. The Laplace series expansion is generalized to a sum in terms of the new fractal mappings.
Holographic Spherically Symmetric Metrics
Petri, Michael
The holographic principle (HP) conjectures, that the maximum number of degrees of freedom of any realistic physical system is proportional to the system's boundary area. The HP has its roots in the study of black holes. It has recently been applied to cosmological solutions. In this article we apply the HP to spherically symmetric static space-times. We find that any regular spherically symmetric object saturating the HP is subject to tight constraints on the (interior) metric, energy-density, temperature and entropy-density. Whenever gravity can be described by a metric theory, gravity is macroscopically scale invariant and the laws of thermodynamics hold locally and globally, the (interior) metric of a regular holographic object is uniquely determined up to a constant factor and the interior matter-state must follow well defined scaling relations. When the metric theory of gravity is general relativity, the interior matter has an overall string equation of state (EOS) and a unique total energy-density. Thus the holographic metric derived in this article can serve as simple interior 4D realization of Mathur's string fuzzball proposal. Some properties of the holographic metric and its possible experimental verification are discussed. The geodesics of the holographic metric describe an isotropically expanding (or contracting) universe with a nearly homogeneous matter-distribution within the local Hubble volume. Due to the overall string EOS the active gravitational mass-density is zero, resulting in a coasting expansion with Ht = 1, which is compatible with the recent GRB-data.
The ETE spherical Tokamak project
Energy Technology Data Exchange (ETDEWEB)
Ludwig, Gerson Otto; Andrade, Maria Celia Ramos de; Barbosa, Luis Filipe Wiltgen [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Lab. Associado de Plasma] [and others]. E-mail: ludwig@plasma.inpe.br
1999-07-01
This paper describes the general characteristics of spherical tokamaks, with a brief overview of work in the area of spherical torus already performed or in progress at several institutions. The paper presents also the historical development of the ETE (Spherical Tokamak Experiment) project, its research program, technical characteristics and status of construction in September, 1998 at the Associated plasma Laboratory (LAP) of the National Institute for Space Research (INPE) in Brazil. (author)
Spherical tokamak development in Brazil
Energy Technology Data Exchange (ETDEWEB)
Ludwig, Gerson Otto; Bosco, Edson Del; Ferreira, Julio Guimaraes [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Lab. Associado de Plasma] (and others)
2003-07-01
The general characteristics of spherical tokamaks, or spherical tori, with a brief view of work in this area already performed or in progress at several institutions worldwide are described. The paper presents also the steps in the development of the ETE (Experiment Tokamak spheric) project, its research program, technical characteristics and operating conditions as of December, 2002 a the Associated Plasma Laboratory (LAP) of the National Space Research Institute (INPE) in Brazil. (author)
L’anagogie poétique. Un dialogue entre Virgile et Platon
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Jelena Pilipović
2010-02-01
Full Text Available Établir des relations constructives entre la poésie de Virgile et certains aspects de la pensée platonicienne constitue le but de notre recherche, dont le texte présenté ici propose une esquisse. Cette recherche n’est fondée ni sur la notion d’influence ni sur celle d’analogie – la première exigeant une approche historique et biographique, la deuxième présupposant un parallélisme entre les deux œuvres antiques –, mais sur la notion de participation constructive. La notion pivot qui permet de défendre cette idée est le concept d’anagogie. L’anagogie ou l’ascension, décrite dans les textes originaux de Platon d’une manière plutôt poétique que théorétique (Phèdre, Symposion, sera incorporée dans le système philosophique de l’époque médioplatonicienne (Didaskalos d’Alkinoos : étant établi le télos suprême de l’existence humaine, elle représente la pénétration de l’âme dans le domaine éïdétique surpassant le monde sensible. Reflétée dans la structure autant que dans le corpus thématique de l’œuvre virgilienne, l’anagogie peut être proclamée comme l’un de ses principes créatifs. Sur le plan structural, la poétique de polysémie et l’idéal des significations cachées forment une hiérarchie sémantique, grâce à laquelle l’acte de lire devient une sorte d’ascension à travers le texte. La forme polysémique graduelle du texte virgilien est le fruit et l’objet central de cet article.The aim of this paper is to establish constructive relations between Virgilian poetry and some aspects of Plato’s thought. The research is based neither on the notion of influence, demanding a historical-biographical approach, nor on the notion of analogy, the two opera not being equal and their relation being causality instead of similarity, but on the notion of constructive participation. The key-point in defending this idea is, consequently, the concept of anagogy. Anagogy, or the
Spherical artifacts on ferrograms
Jones, W. R., Jr.
1976-01-01
In the past, hollow spheres detected on ferrograms have been interpreted as being due to fretting, abrasion, cavitation erosion, and fatigue-related processes. Here it is reported that such spheres were found to result from the fact that a routine grinding operation on a steel plate was carried out about 20 feet away from the ferrograph. A similar grinding operation was performed on a piece of low carbon steel a few feet from the ferrograph, and after a few minutes of grinding, the resulting ferrogram contained thousands of particles of which more than 90% were spherical. Because of the widespread occurrence of ordinary grinding operations, it seems prudent that those utilizing the ferrograph be cognizant of this type of artifact.
Spherical grating spectrometers
O'Donoghue, Darragh; Clemens, J. Christopher
2014-07-01
We describe designs for spectrometers employing convex dispersers. The Offner spectrometer was the first such instrument; it has almost exclusively been employed on satellite platforms, and has had little impact on ground-based instruments. We have learned how to fabricate curved Volume Phase Holographic (VPH) gratings and, in contrast to the planar gratings of traditional spectrometers, describe how such devices can be used in optical/infrared spectrometers designed specifically for curved diffraction gratings. Volume Phase Holographic gratings are highly efficient compared to conventional surface relief gratings; they have become the disperser of choice in optical / NIR spectrometers. The advantage of spectrometers with curved VPH dispersers is the very small number of optical elements used (the simplest comprising a grating and a spherical mirror), as well as illumination of mirrors off axis, resulting in greater efficiency and reduction in size. We describe a "Half Offner" spectrometer, an even simpler version of the Offner spectrometer. We present an entirely novel design, the Spherical Transmission Grating Spectrometer (STGS), and discuss exemplary applications, including a design for a double-beam spectrometer without any requirement for a dichroic. This paradigm change in spectrometer design offers an alternative to all-refractive astronomical spectrometer designs, using expensive, fragile lens elements fabricated from CaF2 or even more exotic materials. The unobscured mirror layout avoids a major drawback of the previous generation of catadioptric spectrometer designs. We describe laboratory measurements of the efficiency and image quality of a curved VPH grating in a STGS design, demonstrating, simultaneously, efficiency comparable to planar VPH gratings along with good image quality. The stage is now set for construction of a prototype instrument with impressive performance.
Spherical wave rotation in spherical near-field antenna measurements
DEFF Research Database (Denmark)
Wu, Jian; Larsen, Flemming Holm; Lemanczyk, J.
1991-01-01
The rotation of spherical waves in spherical near-field antenna measurement is discussed. Considering the many difficult but interesting features of the rotation coefficients, an efficient rotation scheme is derived. The main feature of the proposed scheme is to ignore the calculation of the very...
Spek, Anthony L
2015-01-01
The completion of a crystal structure determination is often hampered by the presence of embedded solvent molecules or ions that are seriously disordered. Their contribution to the calculated structure factors in the least-squares refinement of a crystal structure has to be included in some way. Traditionally, an atomistic solvent disorder model is attempted. Such an approach is generally to be preferred, but it does not always lead to a satisfactory result and may even be impossible in cases where channels in the structure are filled with continuous electron density. This paper documents the SQUEEZE method as an alternative means of addressing the solvent disorder issue. It conveniently interfaces with the 2014 version of the least-squares refinement program SHELXL [Sheldrick (2015). Acta Cryst. C71. In the press] and other refinement programs that accept externally provided fixed contributions to the calculated structure factors. The PLATON SQUEEZE tool calculates the solvent contribution to the structure factors by back-Fourier transformation of the electron density found in the solvent-accessible region of a phase-optimized difference electron-density map. The actual least-squares structure refinement is delegated to, for example, SHELXL. The current versions of PLATON SQUEEZE and SHELXL now address several of the unnecessary complications with the earlier implementation of the SQUEEZE procedure that were a necessity because least-squares refinement with the now superseded SHELXL97 program did not allow for the input of fixed externally provided contributions to the structure-factor calculation. It is no longer necessary to subtract the solvent contribution temporarily from the observed intensities to be able to use SHELXL for the least-squares refinement, since that program now accepts the solvent contribution from an external file (.fab file) if the ABIN instruction is used. In addition, many twinned structures containing disordered solvents are now also
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Reza korrang beheshti
2014-06-01
Full Text Available Although there is not a fully developed theory of evil in Plato, some various remarks are interspersed throughout his dialogues which provided the main materials for subsequent Platonists to elaborate a systematic doctrine of evil. Proclus is the most distinguished philosopher of the later Neoplatonism whose view became authoritative within the School and thus is most representative of the Neoplatonic doctrine of evil. By a critical assessment of the antecedent theories of evil, Proclus attempts to give a monistic interpretation of Platonic remarks on the problem of evil. According to his explanation, the higher degrees and principles of Being are only and purely good and are not the causes of evils but the good things for all things alone. Evils, however, exist necessarily but only among particular beings in a relative, parasitic, accidental way and dependent upon the good. The parasitic accidental existence of evil does not have a real efficient cause. It arises due to an asymmetry between the activities of the several faculties or powers of a complex particular being. Moreover, the existence of evil is so mixed with and dependent upon the good that despite its opposition to the good, contributes, in its own manner, to the fulfillment of goodness of the whole Universe, being thus reconcilable with Divine Providence and Efficiency.
Spherical 3D isotropic wavelets
Lanusse, F.; Rassat, A.; Starck, J.-L.
2012-04-01
Context. Future cosmological surveys will provide 3D large scale structure maps with large sky coverage, for which a 3D spherical Fourier-Bessel (SFB) analysis in spherical coordinates is natural. Wavelets are particularly well-suited to the analysis and denoising of cosmological data, but a spherical 3D isotropic wavelet transform does not currently exist to analyse spherical 3D data. Aims: The aim of this paper is to present a new formalism for a spherical 3D isotropic wavelet, i.e. one based on the SFB decomposition of a 3D field and accompany the formalism with a public code to perform wavelet transforms. Methods: We describe a new 3D isotropic spherical wavelet decomposition based on the undecimated wavelet transform (UWT) described in Starck et al. (2006). We also present a new fast discrete spherical Fourier-Bessel transform (DSFBT) based on both a discrete Bessel transform and the HEALPIX angular pixelisation scheme. We test the 3D wavelet transform and as a toy-application, apply a denoising algorithm in wavelet space to the Virgo large box cosmological simulations and find we can successfully remove noise without much loss to the large scale structure. Results: We have described a new spherical 3D isotropic wavelet transform, ideally suited to analyse and denoise future 3D spherical cosmological surveys, which uses a novel DSFBT. We illustrate its potential use for denoising using a toy model. All the algorithms presented in this paper are available for download as a public code called MRS3D at http://jstarck.free.fr/mrs3d.html
Topological Lensing in Spherical Spaces
Gausmann, E; Luminet, Jean Pierre; Uzan, J P; Weeks, J; Gausmann, Evelise; Lehoucq, Roland; Luminet, Jean-Pierre; Uzan, Jean-Philippe; Weeks, Jeffrey
2001-01-01
This article gives the construction and complete classification of all three-dimensional spherical manifolds, and orders them by decreasing volume, in the context of multiconnected universe models with positive spatial curvature. It discusses which spherical topologies are likely to be detectable by crystallographic methods using three-dimensional catalogs of cosmic objects. The expected form of the pair separation histogram is predicted (including the location and height of the spikes) and is compared to computer simulations, showing that this method is stable with respect to observational uncertainties and is well suited for detecting spherical topologies.
Spherical tokamak development in Brazil
Energy Technology Data Exchange (ETDEWEB)
Ludwig, G.O.; Del Bosco, E.; Ferreira, J.G.; Berni, L.A.; Oliveira, R.M.; Andrade, M.C.R.; Shibata, C.S.; Ueda, M.; Barroso, J.J.; Castro, P.J. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Lab. Associado de Plasma; Barbosa, L.F.W. [Universidade do Vale do Paraiba (UNIVAP), Sao Jose dos Campos, SP (Brazil). Faculdade de Engenharia, Arquitetura e Urbanismo; Patire Junior, H. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Div. de Mecanica Espacial e Controle; The high-power microwave sources group
2003-12-01
This paper describes the general characteristics of spherical tokamaks, or spherical tori, with a brief overview of work in this area already performed or in progress at several institutions worldwide. The paper presents also the steps in the development of the ETE (Experimento Tokamak Esferico) project, its research program, technical characteristics and operating conditions as of December, 2002 at the Associated Plasma Laboratory (LAP) of the National Space Research Institute (INPE) in Brazil. (author)
SPHERICAL SHOCK WAVES IN SOLIDS
Differential Equation of Self-Similar Motion; Application of the Theory of Self-Similar Motion to the Problem of Expansion of a Spherical...Self-Similar Solutions of the Problem of Cratering Due to Hypervelocity Impact, and Numerical Integration of the Differential Equation of Spherical...Aluminum, Blast Waves in Other Metals; and Consideration of the Non-Similar Aspects of the Blast Wave Problem ; Experimental Procedure and Results; Singular Point of Ordinary Differential Equations; Numerical Program-Fortran
Spherical 3D Isotropic Wavelets
Lanusse, F; Starck, J -L
2011-01-01
Future cosmological surveys will provide 3D large scale structure maps with large sky coverage, for which a 3D Spherical Fourier-Bessel (SFB) analysis in is natural. Wavelets are particularly well-suited to the analysis and denoising of cosmological data, but a spherical 3D isotropic wavelet transform does not currently exist to analyse spherical 3D data. The aim of this paper is to present a new formalism for a spherical 3D isotropic wavelet, i.e. one based on the Fourier-Bessel decomposition of a 3D field and accompany the formalism with a public code to perform wavelet transforms. We describe a new 3D isotropic spherical wavelet decomposition based on the undecimated wavelet transform (UWT) described in Starck et al. 2006. We also present a new fast Discrete Spherical Fourier-Bessel Transform (DSFBT) based on both a discrete Bessel Transform and the HEALPIX angular pixelisation scheme. We test the 3D wavelet transform and as a toy-application, apply a denoising algorithm in wavelet space to the Virgo large...
Milking the spherical cow: on aspherical dynamics in spherical coordinates
Pontzen, Andrew; Teyssier, Romain; Governato, Fabio; Gualandris, Alessia; Roth, Nina; Devriendt, Julien
2015-01-01
Galaxies and the dark matter halos that host them are not spherically symmetric, yet spherical symmetry is a helpful simplifying approximation for idealised calculations and analysis of observational data. The assumption leads to an exact conservation of angular momentum for every particle, making the dynamics unrealistic. But how much does that inaccuracy matter in practice for analyses of stellar distribution functions, collisionless relaxation, or dark matter core-creation? We provide a general answer to this question for a wide class of aspherical systems; specifically, we consider distribution functions that are "maximally stable", i.e. that do not evolve at first order when external potentials (which arise from baryons, large scale tidal fields or infalling substructure) are applied. We show that a spherically-symmetric analysis of such systems gives rise to the false conclusion that the density of particles in phase space is ergodic (a function of energy alone). Using this idea we are able to demonstra...
Spherical harmonics in texture analysis
Schaeben, Helmut; van den Boogaart, K. Gerald
2003-07-01
The objective of this contribution is to emphasize the fundamental role of spherical harmonics in constructive approximation on the sphere in general and in texture analysis in particular. The specific purpose is to present some methods of texture analysis and pole-to-orientation probability density inversion in a unifying approach, i.e. to show that the classic harmonic method, the pole density component fit method initially introduced as a distinct alternative, and the spherical wavelet method for high-resolution texture analysis share a common mathematical basis provided by spherical harmonics. Since pole probability density functions and orientation probability density functions are probability density functions defined on the sphere Ω3⊂ R3 or hypersphere Ω4⊂ R4, respectively, they belong at least to the space of measurable and integrable functions L1( Ωd), d=3, 4, respectively. Therefore, first a basic and simplified method to derive real symmetrized spherical harmonics with the mathematical property of providing a representation of rotations or orientations, respectively, is presented. Then, standard orientation or pole probability density functions, respectively, are introduced by summation processes of harmonic series expansions of L1( Ωd) functions, thus avoiding resorting to intuition and heuristics. Eventually, it is shown how a rearrangement of the harmonics leads quite canonically to spherical wavelets, which provide a method for high-resolution texture analysis. This unified point of view clarifies how these methods, e.g. standard functions, apply to texture analysis of EBSD orientation measurements.
Spherical membranes in Matrix theory
Kabat, D; Kabat, Daniel; Taylor, Washington
1998-01-01
We consider membranes of spherical topology in uncompactified Matrix theory. In general for large membranes Matrix theory reproduces the classical membrane dynamics up to 1/N corrections; for certain simple membrane configurations, the equations of motion agree exactly at finite N. We derive a general formula for the one-loop Matrix potential between two finite-sized objects at large separations. Applied to a graviton interacting with a round spherical membrane, we show that the Matrix potential agrees with the naive supergravity potential for large N, but differs at subleading orders in N. The result is quite general: we prove a pair of theorems showing that for large N, after removing the effects of gravitational radiation, the one-loop potential between classical Matrix configurations agrees with the long-distance potential expected from supergravity. As a spherical membrane shrinks, it eventually becomes a black hole. This provides a natural framework to study Schwarzschild black holes in Matrix theory.
Spherical Demons: Fast Surface Registration
Yeo, B.T. Thomas; Sabuncu, Mert; Vercauteren, Tom; Ayache, Nicholas; Fischl, Bruce; Golland, Polina
2009-01-01
We present the fast Spherical Demons algorithm for registering two spherical images. By exploiting spherical vector spline interpolation theory, we show that a large class of regularizers for the modified demons objective function can be efficiently implemented on the sphere using convolution. Based on the one parameter subgroups of diffeomorphisms, the resulting registration is diffeomorphic and fast – registration of two cortical mesh models with more than 100k nodes takes less than 5 minutes, comparable to the fastest surface registration algorithms. Moreover, the accuracy of our method compares favorably to the popular FreeSurfer registration algorithm. We validate the technique in two different settings: (1) parcellation in a set of in-vivo cortical surfaces and (2) Brodmann area localization in ex-vivo cortical surfaces. PMID:18979813
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Kurt Hornik
2012-09-01
Full Text Available Clustering text documents is a fundamental task in modern data analysis, requiring approaches which perform well both in terms of solution quality and computational efficiency. Spherical k-means clustering is one approach to address both issues, employing cosine dissimilarities to perform prototype-based partitioning of term weight representations of the documents.This paper presents the theory underlying the standard spherical k-means problem and suitable extensions, and introduces the R extension package skmeans which provides a computational environment for spherical k-means clustering featuring several solvers: a fixed-point and genetic algorithm, and interfaces to two external solvers (CLUTO and Gmeans. Performance of these solvers is investigated by means of a large scale benchmark experiment.
[Spherical crystallization in pharmaceutical technology].
Szabóné, R P; Pintyéné, H K; Kása, P; Erös, I; Hasznosné, N M; Farkas, B
1998-03-01
Physical properties of crystals, such as size, crystal size distribution and morphology, may predetermine the usefulness of crystalline materials in many pharmaceutical application. The above properties can be regulated with the crystallization process. The spherical crystals are suitable for direct tablet-making because of their better flowability and compressibility properties. These crystals can be used in the filling of the capsule. In this work, the spherical crystals such as "single crystal", "poly-crystals" and agglomerates with other excipients are collected from the literature and the experimental results of the authors. A close cooperation between chemists and the pharmaceutical technologists can help for doing steps in this field.
Spherical agglomeration of acetylsalicylic acid
Directory of Open Access Journals (Sweden)
Polowczyk Izabela
2016-01-01
Full Text Available In this paper spherical agglomeration of acetylsalicylic acid was described. In the first step, the system of good and poor solvents as well as bridging liquid was selected. As a result of a preliminary study, ethyl alcohol, water and carbon tetrachloride were used as the good solvent, poor one, and bridging liquid, respectively. Then, the amount of acetylsalicylic acid and the ratio of the solvents as well as the volume of the bridging liquid were examined. In the last step, the agglomeration conditions, such as mixing intensity and time, were investigated. The spherical agglomerates obtained under optimum conditions could be subjected to a tableting process afterwards.
Basketballs as spherical acoustic cavities
Russell, Daniel A.
2010-06-01
The sound field resulting from striking a basketball is found to be rich in frequency content, with over 50 partials in the frequency range of 0-12 kHz. The frequencies are found to closely match theoretical expectations for standing wave patterns inside a spherical cavity. Because of the degenerate nature of the mode shapes, explicit identification of the modes is not possible without internal investigation with a microphone probe. A basketball proves to be an interesting application of a boundary value problem involving spherical coordinates.
Directory of Open Access Journals (Sweden)
Beatrice eDe Gelder
2011-08-01
Full Text Available Whole body expressions are among the main visual stimulus categories that are naturally associated with faces and the neuroscientific investigation of how body expressions are processed has entered the research agenda this last decade. Here we describe the stimulus set of whole body expressions termed Bodily Expressive Action Stimulus Test (BEAST, and we provide validation data for use of these materials by the community of emotion researchers. The database was composed by 254 whole body expressions resulting from 46 actors expressing 4 emotions (anger, fear, happiness and sadness. In all pictures the face of the actor was blurred and participants were asked to categorize the emotions expressed in the stimuli in a four alternative forced choice task. The results show that all emotions are well recognized, with sadness being the easiest, followed by fear, whereas happiness was the most difficult. The BEAST appears as a valuable addition to currently available tools for assessing recognition of affective signals. It can be used in explicit recognition tasks as well as in matching tasks and in implicit tasks, combined either with facial expressions, with affective prosody or presented with affective pictures as context in healthy subjects as well as in neurologically atypical populations.
Platone interprete di se stesso. «Menone» 98a alla luce di «Fedro» 249b-c
Directory of Open Access Journals (Sweden)
Lavinia Maggi
2016-01-01
Full Text Available La definizione di ἐπιστήμη come ὀρθὴ δόξα legata αἰτίας λογισμῷ, che compare in Menone 98a, presenta notevoli difficoltà interpretative non solo per quanto riguarda l’identificazione dell’αἰτία, ma anche per la possibilità o meno di scorgere sullo sfondo di tale enunciazione la teoria delle Idee (nella versione dei cosiddetti “dialoghi della maturità”. La questione può essere affrontata sia considerando il controverso passo all’interno del contesto più ampio del dialogo (dove compare per la prima volta la teoria dell’ἀνάμνησις, che alla teoria delle Idee è strettamente legata, ma anche in relazione a passi di altri dialoghi platonici, in particolare Fedro 249b-c: qui, dove l’epistemologia platonica si sviluppa secondo la teoria delle Idee, la volontà di Platone di alludere direttamente a Menone 98a sembra offrire una chiave interpretativa anche per quella precedente formulazione. La necessità di leggere ogni dialogo secondo le sue specificità (periodo di composizione, argomento principale, tipologia dei personaggi coinvolti non esclude infatti che, almeno in alcuni casi, Platone stabilisca dei collegamenti che consentano una continuità di lettura nel percorso di sviluppo del suo pensiero.
Shearfree Spherically Symmetric Fluid Models
Sharif, M
2013-01-01
We try to find some exact analytical models of spherically symmetric spacetime of collapsing fluid under shearfree condition. We consider two types of solutions: one is to impose a condition on the mass function while the other is to restrict the pressure. We obtain totally of five exact models, and some of them satisfy the Darmois conditions.
Spherical Pendulum, Actions, and Spin
Richter, Peter H.; Dullin, Holger R.; Waalkens, Holger; Wiersig, Jan
1996-01-01
The classical and quantum mechanics of a spherical pendulum are worked out, including the dynamics of a suspending frame with moment of inertia θ. The presence of two separatrices in the bifurcation diagram of the energy-momentum mapping has its mathematical expression in the hyperelliptic nature of
Cyborg beast: a low-cost 3d-printed prosthetic hand for children with upper-limb differences.
Zuniga, Jorge; Katsavelis, Dimitrios; Peck, Jean; Stollberg, John; Petrykowski, Marc; Carson, Adam; Fernandez, Cristina
2015-01-20
There is an increasing number of children with traumatic and congenital hand amputations or reductions. Children's prosthetic needs are complex due to their small size, constant growth, and psychosocial development. Families' financial resources play a crucial role in the prescription of prostheses for their children, especially when private insurance and public funding are insufficient. Electric-powered (i.e., myoelectric) and body-powered (i.e., mechanical) devices have been developed to accommodate children's needs, but the cost of maintenance and replacement represents an obstacle for many families. Due to the complexity and high cost of these prosthetic hands, they are not accessible to children from low-income, uninsured families or to children from developing countries. Advancements in computer-aided design (CAD) programs, additive manufacturing, and image editing software offer the possibility of designing, printing, and fitting prosthetic hands devices at a distance and at very low cost. The purpose of this preliminary investigation was to describe a low-cost three-dimensional (3D)-printed prosthetic hand for children with upper-limb reductions and to propose a prosthesis fitting methodology that can be performed at a distance. No significant mean differences were found between the anthropometric and range of motion measurements taken directly from the upper limbs of subjects versus those extracted from photographs. The Bland and Altman plots show no major bias and narrow limits of agreements for lengths and widths and small bias and wider limits of agreements for the range of motion measurements. The main finding of the survey was that our prosthetic device may have a significant potential to positively impact quality of life and daily usage, and can be incorporated in several activities at home and in school. This investigation describes a low-cost 3D-printed prosthetic hand for children and proposes a distance fitting procedure. The Cyborg Beast
Developement of Spherical Polyurethane Beads
Institute of Scientific and Technical Information of China (English)
K. Maeda; H. Ohmori; H. Gyotoku
2005-01-01
@@ 1Results and Discussion We established a new method to produce the spherical polyurethane beads which have narrower distribution of particle size. This narrower distribution was achieved by the polyurethane prepolymer which contains ketimine as a blocked chain-extending agent. Firstly, the prepolymer is dispersed into the aqueous solution containing surfactant. Secondaly, water comes into the inside of prepolymer as oil phase. Thirdly, ketimine is hydrolyzed to amine, and amine reacts with prepolymer immediately to be polyurethane.Our spherical polyurethane beads are very suitable for automotive interior parts especially for instrument panel cover sheet producing under the slush molding method, because of good process ability, excellent durability to the sunlight and mechanical properties at low temperature. See Fig. 1 ,Fig. 2 and Fig. 3 (Page 820).
Miniaturization of Spherical Magnetodielectric Antennas
DEFF Research Database (Denmark)
Hansen, Troels Vejle
The fundamental limitations in performance of electrically small antennas (ESAs) - and how far these may be approached - have been of great interest for over a century. Particularly over the past few decades, it has become increasingly relevant and important, to approach these limits in view...... to the important antenna parameters of radiation efficiency e and impedance bandwidth. For single-mode antennas the fundamental minimum Q is the Chu lower bound. In this Ph.D. dissertation, the topic is miniaturization of spherical antennas loaded by an internal magnetodielectric core. The goal is to determine......, quantify, and assess the effects of an internal material loading upon antenna performance, including its potentials towards miniaturization. Emphasis have been upon performing an exhaustive and exact analysis of rigorous validity covering a large class of spherical antennas. In the context of this study...
Geodesics of Spherical Dilaton Spacetimes
Institute of Scientific and Technical Information of China (English)
ZENG Yi; L(U) Jun-Li; WANG Yong-Jiu
2006-01-01
The properties of spherical dilaton black hole spacetimes are investigated through a study of their geodesies. The closed and non-closed orbits of test particles are analysed using the effective potential and phase-plane method. The stability and types of orbits are determined in terms of the energy and angular momentum of the test particles. The conditions of the existence of circular orbits for a spherical dilaton spacetime with an arbitrary dilaton coupling constant a are obtained. The properties of the orbits and in particular the position of the innermost stable circular orbit are compared to those of the Reissner-Nordstrom spacetime. The circumferential radius of innermost stable circular orbit and the corresponding angular momentum of the test particles increase for a≠0.
On noncommutative spherically symmetric spaces
Energy Technology Data Exchange (ETDEWEB)
Buric, Maja [University of Belgrade, Faculty of Physics, P.O. Box 44, Belgrade (Serbia); Madore, John [Laboratoire de Physique Theorique, Orsay (France)
2014-03-15
Two families of noncommutative extensions are given of a general space-time metric with spherical symmetry, both based on the matrix truncation of the functions on the sphere of symmetry. The first family uses the truncation to foliate space as an infinite set of spheres, and it is of dimension four and necessarily time-dependent; the second can be time-dependent or static, is of dimension five, and uses the truncation to foliate the internal space. (orig.)
On noncommutative spherically symmetric spaces
Buric, Maja
2014-01-01
Two families of noncommutative extensions are given of a general space-time metric with spherical symmetry, both based on the matrix truncation of the functions on the sphere of symmetry. The first family uses the truncation to foliate space as an infinite set of spheres, is of dimension four and necessarily time-dependent; the second can be time-dependent or static, is of dimension five and uses the truncation to foliate the internal space.
Molecular Simulations using Spherical Harmonics
Institute of Scientific and Technical Information of China (English)
CAI, Wen-Sheng; XU, Jia-Wei; SHAO, Xue-Guang; MAIGRET, Bernard
2003-01-01
Computer-aided drug design is to develop a chemical that binds to a target macromolecule known to play a key role in a disease state. In recognition of ligands by their protein receptors,molecular surfaces are often used because they represent the interacting part of molecules and they should reflex the complementarity between ligand and receptor. However, assessing the surface complementarity by searching all relative position of two surfaces is often computationally expensive. The complementarity of lobe-hole is very important in protein-ligand interactions. Spherical harmonic models based on expansions of spherical harmonic functions were used as a fingerprint to approximate the binding cavity and the ligand, respectively. This defines a new way to identify the complementarity between lobes and holes. The advantage of this method is that two spherical harmonic surfaces to be compared can be defined separately. This method can be used as a filter to eliminate candidates among a large number of conformations, and it will speed up the docking procedure. Therefore, it is possible to select complementary ligands or complementary conformations of a ligand and the macromoleeules, by comparing their fingerprints previously stored in a database.
[Plato psychiatrist, Foucault platonic].
Mathov, Nicolás
2016-05-01
This work explores the links between the concepts of "soul", "law" and "word" in Plato's work, in order to highlight the importance and the centrality of the philosophical-therapeutic dimension in the Greek philosopher's thought. In that way, this work pretends to show that "contemporary" problems usually discussed within "Human Sciences" in general, and Psychiatry in particular, should confront their knowledge with Plato's work, mainly due to the profound influence his ideas have had in our Greco-Christian culture. In that sense, and with that objective, this work also explores Michel Foucault's lucid and controversial interpretation of Plato.
Hawkins, David
1985-01-01
Some questions about the relevance of the philosophy of mathematics to mathematics teaching and to early mathematics learning are discussed. Books by Lakatos, Davis and Hersh, and Kitcher are referred to extensively, with comments on a variety of instructional practices. (MNS)
DEFF Research Database (Denmark)
Tortzen, Gorm
2007-01-01
Den korte dialog 'Kleitofon' hører til den gruppe i Corpus Platonicum, der ofte anses for at være uægte. Indledningen problematiserer dette, der gives en ny ovesættelse, og der føjes en række oplysende noter til teksten. Udgivelsesdato: April...
Socrates: Platonic Political Ideal
Directory of Open Access Journals (Sweden)
Christopher P. Long
2012-01-01
Full Text Available El ensayo articula diferencias y sugiere similitudes entre las prácticas del diálogo político de Sócrates y aquellas de la escritura política de Platón. Propone, además, que tanto el diálogo socrático como la escritura platónica se orientan eróticamente hacia ideales capaces de transformar las vidas de los individuos y sus relaciones. Demuestra que en el Protágoras las prácticas del diálogo socrático se ocupan menos de Protágoras que del joven Hipócrates. En el Fedón, este ideal de Sócrates se amplía de tal manera que la misma escritura platónica aparece como capaz de hacer con los lectores lo que el diálogo de Sócrates hacía con sus interlocutores. Sócrates es el ideal político platónico. El resultado es una visión del poder de transformación política tanto del diálogo socrático como de la escritura platónica.
Platonic Relationships among Resistors
Allen, Bradley; Liu, Tongtian
2015-01-01
Calculating the effective resistance of an electrical network is a common problem in introductory physics courses. Such calculations are typically restricted to two-dimensional networks, though even such networks can become increasingly complex, leading to several studies on their properties. Furthermore, several authors have used advanced…
Directory of Open Access Journals (Sweden)
Maria Chiara Pievatolo
2015-01-01
Full Text Available Nei colloqui precedenti si erano toccate molte opinioni filosofiche sbagliate, e allora Socrate dice: “Sarebbe ben comprensibile se uno, a motivo dell’irritazione per tante cose sbagliate, per il resto della sua vita prendesse in odio ogni discorso sull’essere e lo...
Identificação de radiofontes puntiformes presentes na região observada pelo telescópio BEAST
Oliveira, M. S.; Wuensche, C. A.; Leonardi, R.; Tello, C.
2003-08-01
Radiofontes extragalácticas são um dos principais contaminantes nas medidas da Radiação Cósmica de Fundo (RCF) em freqüências abaixo de 200 GHz. O estudo de seu comportamento espectral permite determinar a contribuição destas fontes às anisotropias intrísincas da RCF. Um dos experimentos recentes concebidos para estudar a RCF é o BEAST (Background Emission Anisotropy Scanning Telescope), cujos primeiros resultados foram publicados em fevereiro de 2003. Nos últimos meses, geramos mapas do céu nas freqüências de 30 GHz e 41 GHz, para um total de 648 horas de observação entre julho e outubro de 2002. Identificamos 4 fontes puntiformes extragalácticas na região do céu situada entre 0h 4,3 e situadas a pelo menos 25° acima do Plano Galáctico. Suas contrapartidas em 5 GHz, segundo o catálogo GB6, são: J1613+3412, J1635+3808, J0927+3902 e J1642+3948. Estas fontes também foram identificadas pelo satélite WMAP sendo que três coincidem com as observadas pelo BEAST dentro da incerteza do feixe do telescópio e a quarta encontra-se bastante próxima (J1613+3412), embora não seja coincidente. As estimativas preliminares de fluxos obtidas para esses objetos são, respectivamente, 0,51; 0,97; 1,08 e 1,6 Jy em 41 GHz. Usando estes resultados e medidas de fluxos em outras frequências existentes na literatura, apresentamos uma estimativa dos índices espectrais destes objetos no intervalo de frequências entre 4,85 GHz e 41 GHz.
Directory of Open Access Journals (Sweden)
José Lourenço Pereira da Silva
2011-03-01
Full Text Available The platonic ontology as known through the Phaedo and Republic is centered on the hypothesis of the intelligible Forms, that is, the platonic Socrates' belief that there are ontologically independent entities such as "the beautiful itself", "the good itself", "the equal itself" etc., of which all empirical things participate thereby receiving the properties they exhibit. Clearly, the main philosophical influences on this doctrine are pre-Socratic philosophy, the sophistic and Socrates' thought. The aim of this paper is to present which ideas or philosophical questions led Plato to postulate the Forms.
A ontologia platônica, como conhecida a partir do Fédon e da República, está centrada na hipótese das Formas inteligíveis, ou seja, a crença defendida pelo Sócrates platônico na existência de entidades ontologicamente independentes, “o belo em si”, “o bem em si”, “o igual em si”, etc., das quais as coisas empíricas participam recebendo por isso as propriedades que exibem. Notoriamente, as principais influências filosóficas dessa doutrina são a filosofia pré-socrática, a sofística e o pensamento de Sócrates. O objetivo deste artigo é mostrar que ideias ou questões filosóficas levaram Platão a postular as Formas.
Energy Technology Data Exchange (ETDEWEB)
Sceats, P.
1997-10-01
Some misconceptions in the financial service sector about opportunities in the European electricity market are explored. One aspect of the electricity business which is misunderstood by the brokerage community is ``spark spread``. This is the differential between the price of electricity sold by a generator and the price of the fuel used to generate it. Although the spark spread can correctly describe a power station`s individual margin it is not yet the easily tradable instrument it is seen to be by some in the broking world. The reason is that to calculate the spark spread two quantities need to be known. One of these, the ``feedstock`` price (gas or coal) is relatively easy to calculate but the other, a meaningful electricity price, is not. The price of electricity on the European market is not the published wholesale price, which is merely a loose basis for what is actually traded between electricity companies. Even if it were possible to isolate a meaningful average figure to be valued against gas or coal prices, it would not take into account the thermal efficiency of the plant and the shape of electricity supply and demand which varies from day to day. The situation is different in the USA, where electricity and gas futures are already set up and trading, and the spread between the two markets is a workable spark spread. (UK)
2003-07-01
Deeply Embedded Massive Stellar Clusters Discovered in Milky Way Powerhouse Summary Peering into a giant molecular cloud in the Milky Way galaxy - known as W49 - astronomers from the European Southern Observatory (ESO) have discovered a whole new population of very massive newborn stars . This research is being presented today at the International Astronomical Union's 25th General Assembly held in Sydney, Australia, by ESO-scientist João Alves. With the help of infrared images obtained during a period of excellent observing conditions with the ESO 3.5-m New Technology Telescope (NTT) at the La Silla Observatory (Chile), the astronomers looked deep into this molecular cloud and discovered four massive stellar clusters, with hot and energetic stars as massive as 120 solar masses. The exceedingly strong radiation from the stars in the largest of these clusters is "powering" a 20 light-year diameter region of mostly ionized hydrogen gas (a "giant HII region"). W49 is one of the most energetic regions of star formation in the Milky Way. With the present discovery, the true sources of the enormous energy have now been revealed for the first time, finally bringing to an end some decades of astronomical speculations and hypotheses. PR Photo 21a/03 : Colour Composite of W49A (NTT+SOFI). PR Photo 21b/03 : Radio and Near-Infrared Composite of W49A Giant molecular clouds Stars form predominantly inside Giant Molecular Clouds which populate our Galaxy, the Milky Way. One of the most prominent of these is W49 , which has a mass of a million solar masses. It is located some 37,000 light-years away and is the most luminous star-forming region known in our home galaxy: its luminosity is several million times the luminosity of our Sun. A smaller region within this cloud is denoted W49A - this is one of the strongest radio-emitting areas known in the Galaxy . Massive stars are excessive in all ways. Compared to their smaller and ligther brethren, they form at an Olympic speed and have a frantic and relatively short life. Formation sites of massive stars are quite rare and, accordingly, most are many thousands of light-years away. For that reason alone, it is in general much more difficult to observe details of massive-star formation. Moreover, as massive stars are generally formed in the main plane of the Galaxy, in the disc where a lot of dust is present, the first stages of such stars are normally hidden behind very thick curtains. In the case of W49A , less than one millionth of the visible light emitted by a star in this region will find its way through the heavy intervening layers of galactic dust and reach the telescopes on Earth. And finally, because massive stars just formed are still very deeply embedded in their natal clouds, they are anyway not detectable at optical wavelengths. Observations of this early phase of the lives of heavy stars must therefore be done at longer wavelengths (where the dust is more transparent), but even so, such natal dusty clouds still absorb a large proportion of the light emitted by the young stars. Infrared observations of W49 ESO PR Photo 21a/03 ESO PR Photo 21a/03 [Preview - JPEG: 464 x 400 pix - 88k [Normal - JPEG: 928 x 800 pix - 972k] ESO PR Photo 21b/03 ESO PR Photo 21b/03 [Preview - JPEG: 400 x 461 pix - 104k [Normal - JPEG: 800 x 922 pix - 1.1M] Captions : PR Photo 21a/03 presents a composite near-infrared colour image from NTT/SofI. It covers a sky area of 5 x 5 arcmin 2 and the red, green and blue colours correspond to the Ks- (wavelength 2.2 µm), H- (1.65 µm) and J-band (1.2 µm), respectively. North is up and East is to the left. The labels identify known radio sources. The main cluster is seen north-east of the region labelled "O3". The colour of a star in this image is mostly a measure of the amount of dust absorption towards this star. Hence, all blue stars in this image are located in front of the star-forming region. PR Photo 21b/03 shows a three-colour composite of the central region of the star-forming region W49A , based on a radio emission map (wavelength 3.6 cm; here rendere
National Research Council Canada - National Science Library
Silvana Paternostro
2011-01-01
... that swept his chosen successor into office, with the handover occurring on September 16. Peña Nieto's presidential appeal has partly to do with voters' anger at the failure of President Felipe...
A charged spherically symmetric solution
Indian Academy of Sciences (India)
K Moodley; S D Maharaj; K S Govinder
2003-09-01
We ﬁnd a solution of the Einstein–Maxwell system of ﬁeld equations for a class of accelerating, expanding and shearing spherically symmetric metrics. This solution depends on a particular ansatz for the line element. The radial behaviour of the solution is fully speciﬁed while the temporal behaviour is given in terms of a quadrature. By setting the charge contribution to zero we regain an (uncharged) perfect ﬂuid solution found previously with the equation of state =+ constant, which is a generalisation of a stiff equation of state. Our class of charged shearing solutions is characterised geometrically by a conformal Killing vector.
Spherically symmetric scalar field collapse
Indian Academy of Sciences (India)
Koyel Ganguly; Narayan Banerjee
2013-03-01
It is shown that a scalar field, minimally coupled to gravity, may have collapsing modes even when the energy condition is violated, that is, for ( + 3) < 0. This result may be useful in the investigation of the possible clustering of dark energy. All the examples dealt with have apparent horizons formed before the formation of singularity. The singularities formed are shell focussing in nature. The density of the scalar field distribution is seen to diverge at singularity. The Ricci scalar also diverges at the singularity. The interior spherically symmetric metric is matched with exterior Vaidya metric at the hypersurface and the appropriate junction conditions are obtained.
Cooperative effects in spherical spasers
DEFF Research Database (Denmark)
Bordo, Vladimir
2017-01-01
a shell/core contains an arbitrarily large number of active molecules in the vicinity of a metallic core/shell. An essential aspect of the theory is an ab initio account of the feedback from the core/shell boundaries which significantly modifies the molecular dynamics. The theory provides rigorous, albeit......A fully analytical semiclassical theory of cooperative optical processes which occur in an ensemble of molecules embedded in a spherical core-shell nanoparticle is developed from first principles. Both the plasmonic Dicke effect and spaser generation are investigated for the designs in which...
Intermittency in spherical Couette dynamos
Raynaud, Raphaël; 10.1103/PhysRevE.87.033011
2013-01-01
We investigate dynamo action in three-dimensional numerical simulations of turbulent spherical Couette flows. Close to the onset of dynamo action, the magnetic field exhibits an intermittent behavior, characterized by a series of short bursts of the magnetic energy separated by low-energy phases. We show that this behavior corresponds to the so-called on-off intermittency. This behavior is here reported for dynamo action with realistic boundary conditions. We investigate the role of magnetic boundary conditions in this phenomenon.
Properties of Fermion Spherical Harmonics
Hunter, G; Hunter, Geoffrey; Emami-Razavi, Mohsen
2005-01-01
The Fermion Spherical harmonics [$Y_\\ell^{m}(\\theta,\\phi)$ for half-odd-integer $\\ell$ and $m$ - presented in a previous paper] are shown to have the same eigenfunction properties as the well-known Boson Spherical Harmonics [$Y_\\ell^{m}(\\theta,\\phi)$ for integer $\\ell$ and $m$]. The Fermion functions are shown to differ from the Boson functions in so far as the ladder operators $M_+$ ($M_-$) that ascend (descend) the sequence of harmonics over the values of $m$ for a given value of $\\ell$, do not produce the expected result {\\em in just one case}: when the value of $m$ changes from $\\pm{1/2}$ to $\\mp{1/2}$; i.e. when $m$ changes sign; in all other cases the ladder operators produce the usually expected result including anihilation when a ladder operator attempts to take $m$ outside the range: $-\\ell\\le m\\le +\\ell$. The unexpected result in the one case does not invalidate this scalar coordinate representation of spin angular momentum, because the eigenfunction property is essential for a valid quantum mechani...
Progress in octahedral spherical hohlraum study
Directory of Open Access Journals (Sweden)
Ke Lan
2016-01-01
Full Text Available In this paper, we give a review of our theoretical and experimental progress in octahedral spherical hohlraum study. From our theoretical study, the octahedral spherical hohlraums with 6 Laser Entrance Holes (LEHs of octahedral symmetry have robust high symmetry during the capsule implosion at hohlraum-to-capsule radius ratio larger than 3.7. In addition, the octahedral spherical hohlraums also have potential superiority on low backscattering without supplementary technology. We studied the laser arrangement and constraints of the octahedral spherical hohlraums, and gave a design on the laser arrangement for ignition octahedral hohlraums. As a result, the injection angle of laser beams of 50°–60° was proposed as the optimum candidate range for the octahedral spherical hohlraums. We proposed a novel octahedral spherical hohlraum with cylindrical LEHs and LEH shields, in order to increase the laser coupling efficiency and improve the capsule symmetry and to mitigate the influence of the wall blowoff on laser transport. We studied on the sensitivity of the octahedral spherical hohlraums to random errors and compared the sensitivity among the octahedral spherical hohlraums, the rugby hohlraums and the cylindrical hohlraums, and the results show that the octahedral spherical hohlraums are robust to these random errors while the cylindrical hohlraums are the most sensitive. Up till to now, we have carried out three experiments on the spherical hohlraum with 2 LEHs on Shenguang(SG laser facilities, including demonstration of improving laser transport by using the cylindrical LEHs in the spherical hohlraums, spherical hohlraum energetics on the SGIII prototype laser facility, and comparisons of laser plasma instabilities between the spherical hohlraums and the cylindrical hohlraums on the SGIII laser facility.
Asymptotic analysis of outwardly propagating spherical flames
Institute of Scientific and Technical Information of China (English)
Yun-Chao Wu; Zheng Chen
2012-01-01
Asymptotic analysis is conducted for outwardly propagating spherical flames with large activation energy.The spherical flame structure consists of the preheat zone,reaction zone,and equilibrium zone.Analytical solutions are separately obtained in these three zones and then asymptotically matched.In the asymptotic analysis,we derive a correlation describing the spherical flame temperature and propagation speed changing with the flame radius.This correlation is compared with previous results derived in the limit of infinite value of activation energy.Based on this correlation,the properties of spherical flame propagation are investigated and the effects of Lewis number on spherical flame propagation speed and extinction stretch rate are assessed.Moreover,the accuracy and performance of different models used in the spherical flame method are examined.It is found that in order to get accurate laminar flame speed and Markstein length,non-linear models should be used.
Institute of Scientific and Technical Information of China (English)
王昇
2013-01-01
柏拉图的美学思想深受其所处时代及其自身哲学思想的影响。柏拉图对于美的本质、艺术的教育功能都有比较深刻的论述。其思想的精华之处至今对于我国的美育、艺术教育仍有重要的借鉴意义。%Platon's aesthetic thought is deeply influenced by the times and his own philosophy. Platon had deeply discussed the nature of beauty and the educational function of art. The essence of his thought is still of important reference meanings for the pre-cent aesthetic education and art education in our country.
The ETE spherical Tokamak project. IAEA report
Energy Technology Data Exchange (ETDEWEB)
Ludwig, Gerson Otto; Del Bosco, E.; Berni, L.A.; Ferreira, J.G.; Oliveira, R.M.; Andrade, M.C.R.; Shibata, C.S.; Barroso, J.J.; Castro, P.J.; Patire Junior, H. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Lab. Associado de Plasma]. E-mail: ludwig@plasma.inpe.br
2002-07-01
This paper describes the general characteristics of spherical tokamaks, or spherical tori, with a brief overview of work in this area already performed or in progress at several institutions worldwide. The paper presents also the historical development of the ETE (Spherical Tokamak Experiment) project, its research program, technical characteristics and operating conditions as of October, 2002 at the Associated Plasma Laboratory (LAP) of the National Space Research Institute (INPE) in Brazil. (author)
Bootstrap Current in Spherical Tokamaks
Institute of Scientific and Technical Information of China (English)
王中天; 王龙
2003-01-01
Variational principle for the neoclassical theory has been developed by including amomentum restoring term in the electron-electron collisional operator, which gives an additionalfree parameter maximizing the heat production rate. All transport coefficients are obtained in-cluding the bootstrap current. The essential feature of the study is that the aspect ratio affects thefunction of the electron-electron collision operator through a geometrical factor. When the aspectratio approaches to unity, the fraction of circulating particles goes to zero and the contribution toparticle flux from the electron-electron collision vanishes. The resulting diffusion coefficient is inrough agreement with Hazeltine. When the aspect ratio approaches to infinity, the results are inagreement with Rosenbluth. The formalism gives the two extreme cases a connection. The theoryis particularly important for the calculation of bootstrap current in spherical tokamaks and thepresent tokamaks, in which the square root of the inverse aspect ratio, in general, is not small.
Coning, symmetry and spherical frameworks
Schulze, Bernd
2011-01-01
In this paper, we combine separate works on (a) the transfer of infinitesimal rigidity results from an Euclidean space to the next higher dimension by coning, (b) the further transfer of these results to spherical space via associated rigidity matrices, and (c) the prediction of finite motions from symmetric infinitesimal motions at regular points of the symmetry-derived orbit rigidity matrix. Each of these techniques is reworked and simplified to apply across several metrics, including the Minkowskian metric $\\M^{d}$ and the hyperbolic metric $\\H^{d}$. This leads to a set of new results transferring infinitesimal and finite motions associated with corresponding symmetric frameworks among $\\E^{d}$, cones in $E^{d+1}$, $\\SS^{d}$, $\\M^{d}$, and $\\H^{d}$. We also consider the further extensions associated with the other Cayley-Klein geometries overlaid on the shared underlying projective geometry.
Libsharp - spherical harmonic transforms revisited
Reinecke, Martin
2013-01-01
We present libsharp, a code library for spherical harmonic transforms (SHTs), which evolved from the libpsht library, addressing several of its shortcomings, such as adding MPI support for distributed memory systems and SHTs of fields with arbitrary spin, but also supporting new developments in CPU instruction sets like the Advanced Vector Extensions (AVX) or fused multiply-accumulate (FMA) instructions. The library is implemented in portable C99 and provides an interface that can be easily accessed from other programming languages such as C++, Fortran, Python etc. Generally, libsharp's performance is at least on par with that of its predecessor; however, significant improvements were made to the algorithms for scalar SHTs, which are roughly twice as fast when using the same CPU capabilities. The library is available at http://sourceforge.net/projects/libsharp/ under the terms of the GNU General Public License.
Dielectric Response of Graded Spherical Composites
Institute of Scientific and Technical Information of China (English)
LI Zhi; WEI En-Bo; ZHANG Han-De; TIAN Ji-Wei
2005-01-01
@@ We investigate the effective dielectric responses of graded spherical composites under an external uniform electric field by taking the dielectric function of spherical inclusion, εi = crkeβr, where r is the inner distance of a point inside the particle from the centre of the spherical particle in the coordination. In the dilute limit, our exact result is used to test the validity of differential effective dipole approximation (DEDA) for estimating the effective response of graded spherical composites and it is shown that the DEDA is in excellent agreement with the exact result.
The geometry of spherical space form groups
Gilkey, Peter B
1989-01-01
In this volume, the geometry of spherical space form groups is studied using the eta invariant. The author reviews the analytical properties of the eta invariant of Atiyah-Patodi-Singer and describes how the eta invariant gives rise to torsion invariants in both K-theory and equivariant bordism. The eta invariant is used to compute the K-theory of spherical space forms, and to study the equivariant unitary bordism of spherical space forms and the Pin c and Spin c equivariant bordism groups for spherical space form groups. This leads to a complete structure theorem for these bordism and K-theor
Spherical Parameterization Balancing Angle and Area Distortions.
Nadeem, Saad; Su, Zhengyu; Zeng, Wei; Kaufman, Arie; Gu, Xianfeng
2017-06-01
This work presents a novel framework for spherical mesh parameterization. An efficient angle-preserving spherical parameterization algorithm is introduced, which is based on dynamic Yamabe flow and the conformal welding method with solid theoretic foundation. An area-preserving spherical parameterization is also discussed, which is based on discrete optimal mass transport theory. Furthermore, a spherical parameterization algorithm, which is based on the polar decomposition method, balancing angle distortion and area distortion is presented. The algorithms are tested on 3D geometric data and the experiments demonstrate the efficiency and efficacy of the proposed methods.
Isovector multiphonon excitations in near spherical nuclei
Smirnova, N A; Pietralla, N; Van Isacker, P; Isacker, Piet Van; Mizusaki, Takahiro; Pietralla, Norbert; Smirnova, Nadya A.
2000-01-01
The lowest isoscalar and isovector quadrupole and octupole excitations in near spherical nuclei are studied within the the proton-neutron version of the interacting boson model including quadrupole and octupole bosons (sdf-IBM-2). The main decay modes of these states in near spherical nuclei are discussed.
The center conjecture for thick spherical buildings
Ramos-Cuevas, Carlos
2009-01-01
We prove that a convex subcomplex of a spherical building of type E7 or E8 is a subbuilding or the group of building automorphisms preserving the subcomplex has a fixed point in it. Together with previous results of Muehlherr-Tits, and Leeb and the author, this completes the proof of Tits' Center Conjecture for thick spherical buildings.
Onthe static and spherically symmetric gravitational field
Gottlieb, Ioan; Maftei, Gheorghe; Mociutchi, Cleopatra
Starting from a generalization of Einstein 's theory of gravitation, proposed by one of the authors (Cleopatra Mociutchi), the authors study a particular spherical symmetric case. Among other one obtain the compatibility conditions for the existence of the static and spherically symmetruic gravitational filed in the case of extended Einstein equation.
Statistical mechanics of thin spherical shells
Kosmrlj, Andrej
2016-01-01
We explore how thermal fluctuations affect the mechanics of thin amorphous spherical shells. In flat membranes with a shear modulus, thermal fluctuations increase the bending rigidity and reduce the in-plane elastic moduli in a scale-dependent fashion. This is still true for spherical shells. However, the additional coupling between the shell curvature, the local in-plane stretching modes and the local out-of-plane undulations, leads to novel phenomena. In spherical shells thermal fluctuations produce a radius-dependent negative effective surface tension, equivalent to applying an inward external pressure. By adapting renormalization group calculations to allow for a spherical background curvature, we show that while small spherical shells are stable, sufficiently large shells are crushed by this thermally generated "pressure". Such shells can be stabilized by an outward osmotic pressure, but the effective shell size grows non-linearly with increasing outward pressure, with the same universal power law expone...
Multi-vector Spherical Monogenics, Spherical Means and Distributions in Clifford Analysis
Institute of Scientific and Technical Information of China (English)
Fred BRACKX; Bram De KNOCK Hennie; De SCHEPPER
2005-01-01
New higher-dimensional distributions have been introduced in the framework of Clifford analysis in previous papers by Brackx, Delanghe and Sommen. Those distributions were defined using spherical co-ordinates, the "finite part" distribution Fp xμ+ on the real line and the generalized spherical means involving vector-valued spherical monogenics. In this paper, we make a second generalization,leading to new families of distributions, based on the generalized spherical means involving a multivector-valued spherical monogenic. At the same time, as a result of our attempt at keeping the paper self-contained, it offers an overview of the results found so far.
Fast calculation of spherical computer generated hologram using spherical wave spectrum method.
Jackin, Boaz Jessie; Yatagai, Toyohiko
2013-01-14
A fast calculation method for computer generation of spherical holograms in proposed. This method is based on wave propagation defined in spectral domain and in spherical coordinates. The spherical wave spectrum and transfer function were derived from boundary value solutions to the scalar wave equation. It is a spectral propagation formula analogous to angular spectrum formula in cartesian coordinates. A numerical method to evaluate the derived formula is suggested, which uses only N(logN)2 operations for calculations on N sampling points. Simulation results are presented to verify the correctness of the proposed method. A spherical hologram for a spherical object was generated and reconstructed successfully using the proposed method.
Some Coincides between Platon and Chinese Philosopher%柏拉图与中国哲学家的几点重合
Institute of Scientific and Technical Information of China (English)
孙蔚
2012-01-01
西方哲学作为西方智慧的千年沉淀,和中国传统文化精神一样都是人类智慧的结晶。柏拉图作为西方最伟大的哲学家之一,他的思想中充满着对世界的深邃解读,浏览柏拉图的思想却发现这些思想不时的和我国的传统思想发生着碰撞,迸发出共同的火花。%Western philosophy as the Western wisdom Millennium precipitation,and the spirit of Chinese traditional culture,is the crystallization of human wisdom.West Platon as one of the greatest philosophers,his mind full of the world deep interpretation of Platon＇s thought,browse and find that these ideas from time to time,and China＇s traditional thought collide,sparks burst out of the common.
Modeling mantle convection in the spherical annulus
Hernlund, John W.; Tackley, Paul J.
2008-12-01
Most methods for modeling mantle convection in a two-dimensional (2D) circular annular domain suffer from innate shortcomings in their ability to capture several characteristics of the spherical shell geometry of planetary mantles. While methods such as rescaling the inner and outer radius to reduce anomalous effects in a 2D polar cylindrical coordinate system have been introduced and widely implemented, such fixes may have other drawbacks that adversely affect the outcome of some kinds of mantle convection studies. Here we propose a new approach that we term the "spherical annulus," which is a 2D slice that bisects the spherical shell and is quantitatively formulated at the equator of a spherical polar coordinate system after neglecting terms in the governing equations related to variations in latitude. Spherical scaling is retained in this approximation since the Jacobian function remains proportional to the square of the radius. We present example calculations to show that the behavior of convection in the spherical annulus compares favorably against calculations performed in other 2D annular domains when measured relative to those in a fully three-dimensional (3D) spherical shell.
Bounce-free Spherical Hydrodynamic Implosion
Kagan, Grigory; Hsu, Scott C; Awe, Thomas J
2011-01-01
In a bounce-free spherical hydrodynamic implosion, the post-stagnation hot core plasma does not expand against the imploding flow. Such an implosion scheme has the advantage of improving the dwell time of the burning fuel, resulting in a higher fusion burn-up fraction. The existence of bounce-free spherical implosions is demonstrated by explicitly constructing a family of self-similar solutions to the spherically symmetric ideal hydrodynamic equations. When applied to a specific example of plasma liner driven magneto-inertial fusion, the bounce-free solution is found to produce at least a factor of four improvement in dwell time and fusion energy gain.
Spherical foam growth in Al alloy melt
Institute of Scientific and Technical Information of China (English)
SHANG; Jintang; HE; Deping
2005-01-01
Due to the demand of high-tech Al alloy foam with spherical pores, high strength and high energy-absorption capacity has become one of the research foci. The aim of this study is to ascertain the growth regularity of spherical foam in Al alloy melt. Three-dimensional packing model such as face-centered cubic is established to study the spherical foam growth. Theoretical results are compared with experimental ones, and the face-centered cubic model corresponds well with the experiment. It is reasonable to assume that the pores have the same radius, the total pore number keeps unchanged and spherical foam grows with face-centered cubic packing mode. This study presents a useful help to control the average pore radius and film thickness.
Recurrence and differential relations for spherical spinors
Szmytkowski, Radosław
2010-01-01
We present a comprehensive table of recurrence and differential relations obeyed by spin one-half spherical spinors (spinor spherical harmonics) $\\Omega_{\\kappa\\mu}(\\mathbf{n})$ used in relativistic atomic, molecular, and solid state physics, as well as in relativistic quantum chemistry. First, we list finite expansions in the spherical spinor basis of the expressions $\\mathbf{A}\\cdot\\mathbf{B}\\,\\Omega_{\\kappa\\mu}(\\mathbf{n})$ and {$\\mathbf{A}\\cdot(\\mathbf{B}\\times\\mathbf{C})\\, \\Omega_{\\kappa\\mu}(\\mathbf{n})$}, where $\\mathbf{A}$, $\\mathbf{B}$, and $\\mathbf{C}$ are either of the following vectors or vector operators: $\\mathbf{n}=\\mathbf{r}/r$ (the radial unit vector), $\\mathbf{e}_{0}$, $\\mathbf{e}_{\\pm1}$ (the spherical, or cyclic, versors), $\\boldsymbol{\\sigma}$ (the $2\\times2$ Pauli matrix vector), $\\hat{\\mathbf{L}}=-i\\mathbf{r}\\times\\boldsymbol{\
Planar and spherical stick indices of knots
Adams, Colin; Hawkins, Katherine; Sia, Charmaine; Silversmith, Rob; Tshishiku, Bena; 10.1142/S0218216511008954
2011-01-01
The stick index of a knot is the least number of line segments required to build the knot in space. We define two analogous 2-dimensional invariants, the planar stick index, which is the least number of line segments in the plane to build a projection, and the spherical stick index, which is the least number of great circle arcs to build a projection on the sphere. We find bounds on these quantities in terms of other knot invariants, and give planar stick and spherical stick constructions for torus knots and for compositions of trefoils. In particular, unlike most knot invariants,we show that the spherical stick index distinguishes between the granny and square knots, and that composing a nontrivial knot with a second nontrivial knot need not increase its spherical stick index.
FY 2005 Miniature Spherical Retroreflectors Final Report
Energy Technology Data Exchange (ETDEWEB)
Anheier, Norman C.; Bernacki, Bruce E.; Johnson, Bradley R.; Riley, Brian J.; Sliger, William A.
2005-12-01
Research done by the Infrared Photonics team at Pacific Northwest National Laboratory (PNNL) is focused on developing miniature spherical retroreflectors using the unique optical and material properties of chalcogenide glass to reduce both performance limiting spherical and chromatic aberrations. The optimized optical performance will provide efficient signal retroreflection that enables a broad range of remote detection scenarios for mid-wave infrared (MWIR) and long-wave infrared (LWIR) sensing applications. Miniature spherical retroreflectors can be developed to aid in the detection of signatures of nuclear proliferation or other chemical vapor or radiation signatures. Miniature spherical retroreflectors are not only well suited to traditional bistatic LIDAR methods for chemical plume detection and identification, but could enable remote detection of difficult semi-volatile chemical materials or low level radiation sources.
Novel Electrically Small Spherical Electric Dipole Antenna
DEFF Research Database (Denmark)
Kim, Oleksiy S.
2010-01-01
of 72 ohms is numerically investigated and its performance is compared to that of the multiarm spherical helix antenna of the same size. Both antennas yield equal quality factors, which are about 1.5 times the Chu lower bound, but quite different cross-polarization characteristics.......This paper introduces a novel electrically small spherical meander antenna. Horizontal sections of the meander are composed of wire loops, radii of which are chosen so that the whole structure is conformal to a sphere of radius a. To form the meander the loops are connected by wires at a meridian...... plane. The antenna operates as an electric dipole, i.e. it radiates the TM10 spherical mode. The antenna is self-resonant and can be matched to a wide range of input feed lines without an external matching network. In this paper, a spherical meander antenna of the size ka = 0.27 and the input impedance...
FY 2006 Miniature Spherical Retroreflectors Final Report
Energy Technology Data Exchange (ETDEWEB)
Anheier, Norman C.; Bernacki, Bruce E.; Krishnaswami, Kannan
2006-12-28
Research done by the Infrared Photonics team at Pacific Northwest National Laboratory (PNNL) is focused on developing miniature spherical retroreflectors using the unique optical and material properties of chalcogenide glass to reduce both performance limiting spherical aberrations. The optimized optical performance will provide efficient signal retroreflection that enables a broad range of remote detection scenarios for mid-wave infrared (MWIR) and long-wave infrared (LWIR) sensing applications. Miniature spherical retroreflectors can be developed to aid in the detection of signatures of nuclear proliferation or other chemical vapor or radiation signatures. Miniature spherical retroreflectors are not only well suited to traditional LIDAR methods for chemical plume detection and identification, but could enable remote detection of difficult semi-volatile chemical materials or low level radiation sources.
Spherically symmetric brane spacetime with bulk gravity
Chakraborty, Sumanta; SenGupta, Soumitra
2015-01-01
Introducing term in the five-dimensional bulk action we derive effective Einstein's equation on the brane using Gauss-Codazzi equation. This effective equation is then solved for different conditions on dark radiation and dark pressure to obtain various spherically symmetric solutions. Some of these static spherically symmetric solutions correspond to black hole solutions, with parameters induced from the bulk. Specially, the dark pressure and dark radiation terms (electric part of Weyl curvature) affect the brane spherically symmetric solutions significantly. We have solved for one parameter group of conformal motions where the dark radiation and dark pressure terms are exactly obtained exploiting the corresponding Lie symmetry. Various thermodynamic features of these spherically symmetric space-times are studied, showing existence of second order phase transition. This phenomenon has its origin in the higher curvature term with gravity in the bulk.
3D Printing Electrically Small Spherical Antennas
DEFF Research Database (Denmark)
Kim, Oleksiy S.
2013-01-01
3D printing is applied for rapid prototyping of an electrically small spherical wire antenna. The model is first printed in plastic and subsequently covered with several layers of conductive paint. Measured results are in good agreement with simulations.......3D printing is applied for rapid prototyping of an electrically small spherical wire antenna. The model is first printed in plastic and subsequently covered with several layers of conductive paint. Measured results are in good agreement with simulations....
3D Printing Electrically Small Spherical Antennas
DEFF Research Database (Denmark)
Kim, Oleksiy S.
2013-01-01
3D printing is applied for rapid prototyping of an electrically small spherical wire antenna. The model is first printed in plastic and subsequently covered with several layers of conductive paint. Measured results are in good agreement with simulations.......3D printing is applied for rapid prototyping of an electrically small spherical wire antenna. The model is first printed in plastic and subsequently covered with several layers of conductive paint. Measured results are in good agreement with simulations....
PREPARATION OF SPHERICAL URANIUM DIOXIDE PARTICLES
Levey, R.P. Jr.; Smith, A.E.
1963-04-30
This patent relates to the preparation of high-density, spherical UO/sub 2/ particles 80 to 150 microns in diameter. Sinterable UO/sub 2/ powder is wetted with 3 to 5 weight per cent water and tumbled for at least 48 hours. The resulting spherical particles are then sintered. The sintered particles are useful in dispersion-type fuel elements for nuclear reactors. (AEC)
Spherical cows in dark matter indirect detection
Bernal, Nicolás; Necib, Lina; Slatyer, Tracy R.
2016-12-01
Dark matter (DM) halos have long been known to be triaxial, but in studies of possible annihilation and decay signals they are often treated as approximately spherical. In this work, we examine the asymmetry of potential indirect detection signals of DM annihilation and decay, exploiting the large statistics of the hydrodynamic simulation Illustris. We carefully investigate the effects of the baryons on the sphericity of annihilation and decay signals for both the case where the observer is at 8.5 kpc from the center of the halo (exemplified in the case of Milky Way-like halos), and for an observer situated well outside the halo. In the case of Galactic signals, we find that both annihilation and decay signals are expected to be quite symmetric, with axis ratios very different from 1 occurring rarely. In the case of extragalactic signals, while decay signals are still preferentially spherical, the axis ratio for annihilation signals has a much flatter distribution, with elongated profiles appearing frequently. Many of these elongated profiles are due to large subhalos and/or recent mergers. Comparing to gamma-ray emission from the Milky Way and X-ray maps of clusters, we find that the gamma-ray background appears less spherical/more elongated than the expected DM signal from the large majority of halos, and the Galactic gamma ray excess appears very spherical, while the X-ray data would be difficult to distinguish from a DM signal by elongation/sphericity measurements alone.
柏拉图分析法在非计划性拔管管理对策中的作用%The Effect of Platon Analysis Method in Unplanned Extubation Management
Institute of Scientific and Technical Information of China (English)
2013-01-01
目的：探讨柏拉图分析法在气管插管非计划性拔管风险管理中的作用。方法：2011年10月-2012年10月应用柏拉图分析对UEX 相关因素进行调查分析，找出主要因素，结合科室实际情况制定切实可行的改进措施。并进行实施前后效果对比。结果：实施后非计划性拔管的发生情况低于实施前（P0.05）。结论：采取柏拉图分析方法能针对性地找出存在的不足，减少气管插管患者非计划性拔管的发生率。%Objective:To investigate effect of the Platon analysis method in tracheal intubation of unplanned extubation risk management. Method:From October 2011 to October 2012,the main factors of UEX were investigated and analyzed by Platon analysis,and the actual formulation of feasible improvement measures were done.compared before and after the implementation effect.Result:After the implementation of UEX occurred less than before(P0.05).Conclusion:Platon analysis method can find out the main problems,reduce the incidence of tracheal intubation in patients with UEX.
Scaling of a fast spherical discharge
Energy Technology Data Exchange (ETDEWEB)
Antsiferov, P. S., E-mail: Ants@isan.troitsk.ru; Dorokhin, L. A. [Russian Academy of Sciences, Institute of Spectroscopy (Russian Federation)
2017-02-15
The influence of the discharge cavity dimensions on the properties of the spherical plasma formed in a fast discharge was studied experimentally. The passage of a current pulse with an amplitude of 30–40 kA and a rise rate of ~10{sup 12} A/s (a fast discharge) through a spherical ceramic (Al{sub 2}O{sub 3}) cavity with an inner diameter of 11 mm filled with argon at a pressure of 80 Pa results in the formation of a 1- to 2-mm-diameter spherical plasma with an electron temperature of several tens of electronvolts and a density of 10{sup 18}–10{sup 19} cm{sup –3}. It is shown that an increase in the inner diameter of the discharge cavity from 11 to 21 mm leads to the fourfold increase in the formation time of the spherical plasma and a decrease in the average ion charge. A decrease in the cavity diameter to 7 mm makes the spherical plasma unstable.
Recent Progress on Spherical Torus Research
Energy Technology Data Exchange (ETDEWEB)
Ono, Masayuki [PPPL; Kaita, Robert [PPPL
2014-01-01
The spherical torus or spherical tokamak (ST) is a member of the tokamak family with its aspect ratio (A = R0/a) reduced to A ~ 1.5, well below the normal tokamak operating range of A ≥ 2.5. As the aspect ratio is reduced, the ideal tokamak beta β (radio of plasma to magnetic pressure) stability limit increases rapidly, approximately as β ~ 1/A. The plasma current it can sustain for a given edge safety factor q-95 also increases rapidly. Because of the above, as well as the natural elongation κ, which makes its plasma shape appear spherical, the ST configuration can yield exceptionally high tokamak performance in a compact geometry. Due to its compactness and high performance, the ST configuration has various near term applications, including a compact fusion neutron source with low tritium consumption, in addition to its longer term goal of attractive fusion energy power source. Since the start of the two megaampere class ST facilities in 2000, National Spherical Torus Experiment (NSTX) in the US and Mega Ampere Spherical Tokamak (MAST) in UK, active ST research has been conducted worldwide. More than sixteen ST research facilities operating during this period have achieved remarkable advances in all of fusion science areas, involving fundamental fusion energy science as well as innovation. These results suggest exciting future prospects for ST research both near term and longer term. The present paper reviews the scientific progress made by the worldwide ST research community during this new mega-ampere-ST era.
Statistical Mechanics of Thin Spherical Shells
Košmrlj, Andrej; Nelson, David R.
2017-01-01
We explore how thermal fluctuations affect the mechanics of thin amorphous spherical shells. In flat membranes with a shear modulus, thermal fluctuations increase the bending rigidity and reduce the in-plane elastic moduli in a scale-dependent fashion. This is still true for spherical shells. However, the additional coupling between the shell curvature, the local in-plane stretching modes, and the local out-of-plane undulations leads to novel phenomena. In spherical shells, thermal fluctuations produce a radius-dependent negative effective surface tension, equivalent to applying an inward external pressure. By adapting renormalization group calculations to allow for a spherical background curvature, we show that while small spherical shells are stable, sufficiently large shells are crushed by this thermally generated "pressure." Such shells can be stabilized by an outward osmotic pressure, but the effective shell size grows nonlinearly with increasing outward pressure, with the same universal power-law exponent that characterizes the response of fluctuating flat membranes to a uniform tension.
Friction factor for water flow through packed beds of spherical and non-spherical particles
Directory of Open Access Journals (Sweden)
Kaluđerović-Radoičić Tatjana
2017-01-01
Full Text Available The aim of this work was the experimental evaluation of different friction factor correlations for water flow through packed beds of spherical and non-spherical particles at ambient temperature. The experiments were performed by measuring the pressure drop across the bed. Packed beds made of monosized glass spherical particles of seven different diameters were used, as well as beds made of 16 fractions of quartz filtration sand obtained by sieving (polydisperse non-spherical particles. The range of bed voidages was 0.359–0.486, while the range of bed particle Reynolds numbers was from 0.3 to 286 for spherical particles and from 0.1 to 50 for non-spherical particles. The obtained results were compared using a number of available literature correlations. In order to improve the correlation results for spherical particles, a new simple equation was proposed in the form of Ergun’s equation, with modified coefficients. The new correlation had a mean absolute deviation between experimental and calculated values of pressure drop of 9.04%. For non-spherical quartz filtration sand particles the best fit was obtained using Ergun’s equation, with a mean absolute deviation of 10.36%. Surface-volume diameter (dSV necessary for correlating the data for filtration sand particles was calculated based on correlations for dV = f(dm and Ψ = f(dm. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. ON172022
Background reduction of a spherical gaseous detector
Fard, Ali Dastgheibi; Loaiza, Pia; Piquemal, Fabrice; Giomataris, Ioannis; Gray, David; Gros, Michel; Magnier, Patrick; Navick, Xavier-François; Savvidis, Ilias
2015-08-01
The Spherical gaseous detector (or Spherical Proportional Counter, SPC) is a novel type of detector. It consists of a large spherical volume filled with gas, using a single detection readout channel. The detector allows 100 % detection efficiency. SEDINE is a low background version of SPC installed at the Laboratoire Souterrain de Modane (LSM) underground laboratory (4800 m.w.e) looking for rare events at very low energy threshold, below 100 eV. This work presents the details on the chemical cleaning to reduce internal 210Pb surface contamination on the copper vessel and the external radon reduction achieved via circulation of pure air inside anti-radon tent. It will be also show the radon measurement of pure gases (Ar, N, Ne, etc) which are used in the underground laboratory for the low background experiments.
Homogeneous spacelike singularities inside spherical black holes
Burko, L M
1997-01-01
Recent numerical simulations have found that the Cauchy horizon inside spherical charged black holes, when perturbed nonlinearly by a self-gravitating, minimally-coupled, massless, spherically-symmetric scalar field, turns into a null weak singularity which focuses monotonically to $r=0$ at late times, where the singularity becomes spacelike. Our main objective is to study this spacelike singularity. We study analytically the spherically-symmetric Einstein-Maxwell-scalar equations asymptotically near the singularity. We obtain a series-expansion solution for the metric functions and for the scalar field near $r=0$ under the simplifying assumption of homogeneity. Namely, we neglect spatial derivatives and keep only temporal derivatives. We find that there indeed exists a generic spacelike singularity solution for these equations (in the sense that the solution depends on enough free parameters), with similar properties to those found in the numerical simulations. This singularity is strong in the Tipler sense,...
Stability of spherical converging shock wave
Energy Technology Data Exchange (ETDEWEB)
Murakami, M., E-mail: murakami-m@ile.osaka-u.ac.jp [Institute of Laser Engineering, Osaka University, Osaka 565-0871 (Japan); Sanz, J. [ETSI Aeronauticos, Universidad Politecnica de Madrid, Madrid 28040 (Spain); Iwamoto, Y. [Graduate School of Science and Engineering, Ehime University, Ehime 790-8577 (Japan)
2015-07-15
Based on Guderley's self-similar solution, stability of spherical converging shock wave is studied. A rigorous linear perturbation theory is developed, in which the growth rate of perturbation is given as a function of the spherical harmonic number ℓ and the specific heats ratio γ. Numerical calculation reveals the existence of a γ-dependent cut-off mode number ℓ{sub c}, such that all the eigenmode perturbations for ℓ > ℓ{sub c} are smeared out as the shock wave converges at the center. The analysis is applied to partially spherical geometries to give significant implication for different ignition schemes of inertial confinement fusion. Two-dimensional hydrodynamic simulations are performed to verify the theory.
A quadrilateralized spherical cube Earth data base
Chan, F. K.
1980-01-01
A quadrilateralized spherical cube was constructed to form the basis for the rapid storage and retrieval of high resolution data obtained of the Earth's surface. The structure of this data base was derived from a spherical cube, which was obtained by radially projecting a cube onto its circumscribing sphere. An appropriate set of curvilinear coordinates were chosen such that the resolution cells on the spherical cube were of equal area and were also of essentially the same shape. The main properties of the Earth data base were that the indexing scheme was binary and telescopic in nature, the resolution cells were strung together in a two dimensional manner, the cell addresses were easily computed, and the conversion from geographic to data base coordinates was comparatively simple. It was concluded that this data base structure was perhaps the most viable one for handling remotely sensed data obtained by satellites.
Background reduction of a spherical gaseous detector
Energy Technology Data Exchange (ETDEWEB)
Fard, Ali Dastgheibi [Laboratoire Souterrain de Modane, France ali.dastgheibi-fard@lsm.in2p3.fr (France); Loaiza, Pia; Piquemal, Fabrice [Laboratoire Souterrain de Modane (France); Giomataris, Ioannis; Gray, David; Gros, Michel; Magnier, Patrick; Navick, Xavier-François [CEA Saclay - IRFU/SEDI - 91191 Gif sur Yvette (France); Savvidis, Ilias [Aristotle University of Thessaloniki (Greece)
2015-08-17
The Spherical gaseous detector (or Spherical Proportional Counter, SPC) is a novel type of detector. It consists of a large spherical volume filled with gas, using a single detection readout channel. The detector allows 100 % detection efficiency. SEDINE is a low background version of SPC installed at the Laboratoire Souterrain de Modane (LSM) underground laboratory (4800 m.w.e) looking for rare events at very low energy threshold, below 100 eV. This work presents the details on the chemical cleaning to reduce internal {sup 210}Pb surface contamination on the copper vessel and the external radon reduction achieved via circulation of pure air inside anti-radon tent. It will be also show the radon measurement of pure gases (Ar, N, Ne, etc) which are used in the underground laboratory for the low background experiments.
Stability of Self-Similar Spherical Accretion
Gaite, J
2006-01-01
Spherical accretion flows are simple enough for analytical study, by solution of the corresponding fluid dynamic equations. The solutions of stationary spherical flow are due to Bondi. The questions of the choice of a physical solution and of stability have been widely discussed. The answer to these questions is very dependent on the problem of boundary conditions, which vary according to whether the accretor is a compact object or a black hole. We introduce a particular, simple form of stationary spherical flow, namely, self-similar Bondi flow, as a case with physical interest in which analytic solutions for perturbations can be found. With suitable no matter-flux-perturbation boundary conditions, we will show that acoustic modes are stable in time and have no spatial instability at r=0. Furthermore, their evolution eventually becomes ergodic-like and shows no trace of instability or of acquiring any remarkable pattern.
Static spherically symmetric wormholes with isotropic pressure
Cataldo, Mauricio; Rodríguez, Pablo
2016-01-01
In this paper we study static spherically symmetric wormhole solutions sustained by matter sources with isotropic pressure. We show that such spherical wormholes do not exist in the framework of zero-tidal-force wormholes. On the other hand, it is shown that for the often used power-law shape function there is no spherically symmetric traversable wormholes sustained by sources with a linear equation of state $p=\\omega \\rho$ for the isotropic pressure, independently of the form of the redshift function $\\phi(r)$. We consider a solution obtained by Tolman at 1939 for describing static spheres of isotropic fluids, and show that it also may describe wormhole spacetimes with a power-law redshift function, which leads to a polynomial shape function, generalizing a power-law shape function, and inducing a solid angle deficit.
DEFF Research Database (Denmark)
Hansen, Troels V.; Kim, Oleksiy S.; Breinbjerg, Olav
2012-01-01
We present closed-form expressions for central properties of spherical wave functions of arbitrary order in relation to arbitrarily sized spherical antennas with lossless solid material cores. These properties are the electric or magnetic spherical surface current distribution radiating a spherical...
Preparation of Spherical Microfinc Silicon Powder
Institute of Scientific and Technical Information of China (English)
SHENG Yong; Zou Jun; LI Bing; TU Mingjing
2008-01-01
Under certain conditions of proper temperature and pH value,sodium silicate was hydrolyzed in liquid ammonia chloride,and spherical microfine SiO2 powder in micrometer-size was prepared.In this experiment,the relationship between needed time and proper pH value,temperature,density ofthe solution.and its current capacity were found.The optimum conditions are pH 8.5,70℃,and the concentration of sodium silicate is O.6 mol/L for the density ofthe solution.The structure of spherical microfine silicon was charactetized by SEM andXRD.
Sphericizing metal powders by mechanical means
Institute of Scientific and Technical Information of China (English)
WANG Fu-xiang; GAI Guo-sheng; YANG Yu-fen
2006-01-01
A dry mechanical surface treatment was described,in which irregularly shaped metal powders were impacted and sphericized by using high speed airflow impact method particles composite system(PCS). The optimum technological parameters for the metal powders processed were determined according to the treatment effect under different conditions. The results show that the irregularly shaped metal powders are impacted into dense spherical particles,the bulk density and tap density of the metal powders increase noticeably. The combination property of metal powders is improved greatly.
Toroidal membrane vesicles in spherical confinement
Bouzar, Lila; Müller, Martin Michael
2015-01-01
We investigate the morphology of a toroidal fluid membrane vesicle confined inside a spherical container. The equilibrium shapes are assembled in a geometrical phase diagram as a function of scaled area and reduced volume of the membrane. For small area the vesicle can adopt its free form. When increasing the area, the membrane cannot avoid contact and touches the confining sphere along a circular contact line, which extends to a zone of contact for higher area. The elastic energies of the equilibrium shapes are compared to those of their confined counterparts of spherical topology to predict under which conditions a topology change is favored energetically.
Toroidal membrane vesicles in spherical confinement
Bouzar, Lila; Menas, Ferhat; Müller, Martin Michael
2015-09-01
We investigate the morphology of a toroidal fluid membrane vesicle confined inside a spherical container. The equilibrium shapes are assembled in a geometrical phase diagram as a function of scaled area and reduced volume of the membrane. For small area the vesicle can adopt its free form. When increasing the area, the membrane cannot avoid contact and touches the confining sphere along a circular contact line, which extends to a zone of contact for higher area. The elastic energies of the equilibrium shapes are compared to those of their confined counterparts of spherical topology to predict under which conditions a topology change is favored energetically.
Overview of spherical tokamak research in Japan
Takase, Y.; Ejiri, A.; Fujita, T.; Fukumoto, N.; Fukuyama, A.; Hanada, K.; Idei, H.; Nagata, M.; Ono, Y.; Tanaka, H.; Uchida, M.; Horiuchi, R.; Kamada, Y.; Kasahara, H.; Masuzaki, S.; Nagayama, Y.; Oishi, T.; Saito, K.; Takeiri, Y.; Tsuji-Iio, S.
2017-10-01
Nationally coordinated research on spherical tokamak is being conducted in Japan. Recent achievements include: (i) plasma current start-up and ramp-up without the use of the central solenoid by RF waves (in electron cyclotron and lower hybrid frequency ranges), (ii) plasma current start-up by AC Ohmic operation and by coaxial helicity injection, (iii) development of an advanced fuelling technique by compact toroid injection, (iv) ultra-long-pulse operation and particle control using a high temperature metal wall, (v) access to the ultra-high-β regime by high-power reconnection heating, and (vi) improvement of spherical tokamak plasma stability by externally applied helical field.
POLARON IN CYLINDRICAL AND SPHERICAL QUANTUM DOTS
Directory of Open Access Journals (Sweden)
L.C.Fai
2004-01-01
Full Text Available Polaron states in cylindrical and spherical quantum dots with parabolic confinement potentials are investigated applying the Feynman variational principle. It is observed that for both kinds of quantum dots the polaron energy and mass increase with the increase of Frohlich electron-phonon coupling constant and confinement frequency. In the case of a spherical quantum dot, the polaron energy for the strong coupling is found to be greater than that of a cylindrical quantum dot. The energy and mass are found to be monotonically increasing functions of the coupling constant and the confinement frequency.
Hole Size in a Spherical Resonator
Directory of Open Access Journals (Sweden)
Jared Kearns
2012-06-01
Full Text Available When air is blown strongly through a straw and across a hole in a hollow sphere, a high-pitched whistling sound is heard. This paper tests two models, Helmholtz Resonance and Spherical Harmonics, to determine which most accurately models this phenomenon. This was done by measuring the frequencies produced when air was blown across identical spheres with different hole sizes, as well as across spheres of different volumes with identical holes. The frequencies were found to closely match frequencies predicted by spherical harmonics.
Hole Size in a Spherical Resonator
Directory of Open Access Journals (Sweden)
Jared Kearns
2012-06-01
Full Text Available When air is blown strongly through a straw and across a hole in a hollow sphere, a high-pitched whistling sound is heard. This paper tests two models, Helmholtz Resonance and Spherical Harmonics, to determine which most accurately models this phenomenon. This was done by measuring the frequencies produced when air was blown across identical spheres with different hole sizes, as well as across spheres of different volumes with identical holes. The frequencies were found to closely match frequencies predicted by spherical harmonics
Spherical Black Holes cannot Support Scalar Hair
Sudarsky, D
1998-01-01
The static spherically symmetric ``black hole solution" of the Einstein - conformally invariant massless scalar field equations known as the BBMB ( Bocharova, , Bronikov, Melinkov, Bekenstein) black hole is critically examined. It is shown that the stress energy tensor is ill-defined at the horizon, and that its evaluation through suitable regularization yields ambiguous results. Consequently, the configuration fails to represent a genuine black hole solution. With the removal of this solution as a counterexample to the no hair conjecture, we argue that the following appears to be true: Spherical black holes cannot carry any kind of classical scalar hair.
Fast algorithms for spherical harmonic expansions, III
Tygert, Mark
2009-01-01
We accelerate the computation of spherical harmonic transforms, using what is known as the butterfly scheme. This provides a convenient alternative to the approach taken in the second paper from this series on "Fast algorithms for spherical harmonic expansions." The requisite precomputations become manageable when organized as a "depth-first traversal" of the program's control-flow graph, rather than as the perhaps more natural "breadth-first traversal" that processes one-by-one each level of the multilevel procedure. We illustrate the results via several numerical examples.
Analysis on two novel spherical helical antennas
Institute of Scientific and Technical Information of China (English)
Hou ZHANG; Yingzeng YIN; Dongyu XIA
2009-01-01
Two novel spherical helical antennas are designed by projecting the planar equiangular spiral antenna onto hemisphere and partial sphere surfaces.Their radiation properties are analyzed by the moment method with curved basis and test function,and the curves of the voltage standing wave ratio (VSWR),gain,polarization and pattern that change with frequency are also given,respectively.It can be seen that the circular polarization band of the novel hemispherical helical antenna is broader.The gain curve of the partial spherical helical antenna is flatter and the structure is simpler.
Inflation in spherically symmetric inhomogeneous models
Energy Technology Data Exchange (ETDEWEB)
Stein-Schabes, J.A.
1986-11-01
Exact analytical solutions of Einstein's equations are found for a spherically symmetric inhomogeneous metric in the presence of a massless scalar field with a flat potential. The process of isotropization and homogenization is studied in detail. It is found that the time dependence of the metric becomes de Sitter for large times. Two cases are studied. The first deals with a homogeneous scalar field, while the second with a spherically symmetric inhomogeneous scalar field. In the former case the metric is of the Robertson-Walker form, while the latter is intrinsically inhomogeneous. 16 refs.
Simulation on the aggregation process of spherical particle confined in a spherical shell
Wang, J.; Xu, J. J.; Zhang, L.
2016-04-01
The aggregation process of spherical particles confined in a spherical shell was studied by using a diffusion-limited cluster-cluster aggregation (DLCA) model. The influence of geometrical confinement and wetting-like properties of the spherical shell walls on the particle concentration profile, aggregate structure and aggregation kinetics had been explored. The results show that there will be either depletion or absorption particles near the shell walls depending on the wall properties. It is observed that there are four different types of density distribution which can be realized by modifying the property of the inner or outer spherical shell wall. In addition, the aggregate structure will become more compact in the confined spherical shell comparing to bulk system with the same particle volume fraction. The analysis on the aggregation kinetics indicates that geometrical confinement will promote the aggregation process by reducing the invalid movement of the small aggregates and by constraining the movement of those large aggregates. Due to the concave geometrical characteristic of the outer wall of the spherical shell, its effects on the aggregating kinetics and the structure of the formed aggregates are more evident than those of the inner wall. This study will provide some instructive information of controlling the density distribution of low-density porous polymer hollow spherical shells and helps to predict gel structures developed in confined geometries.
Magnetic moments of odd spherical nuclei
Energy Technology Data Exchange (ETDEWEB)
Levon, A.I.; Fedotkin, S.N.; Vdovin, A.I.
1986-06-01
Using the quasiparticle-phonon model, the magnetic moments of the ground state and several of the excited states are calculated for spherical nuclei. The polarization of the core is taken into account, by means of 1+ phonons, as well as 2/sup +/ and 3/sup -/ excitations, which give a collective contribution to the magnetic moment.
Noncommutative spherically symmetric spacetimes at semiclassical order
Fritz, Christopher
2016-01-01
Working within the recent formalism of Poisson-Riemannian geometry, we completely solve the case of generic spherically symmetric metric and spherically symmetric Poisson-bracket to find a unique answer for the quantum differential calculus, quantum metric and quantum Levi-Civita connection at semiclassical order $O(\\lambda)$. Here $\\lambda$ is the deformation parameter, plausibly the Planck scale. We find that $r,t,dr,dt$ are all forced to be central, i.e. undeformed at order $\\lambda$, while for each value of $r,t$ we are forced to have a fuzzy sphere of radius $r$ with a unique differential calculus which is necessarily nonassociative at order $\\lambda^2$. We give the spherically symmetric quantisation of the FLRW cosmology in detail and also recover a previous analysis for the Schwarzschild black hole, now showing that the quantum Ricci tensor for the latter vanishes at order $\\lambda$. The quantum Laplace-Beltrami operator for spherically symmetric models turns out to be undeformed at order $\\lambda$ whi...
Optical properties of spherical gold mesoparticles
DEFF Research Database (Denmark)
Evlyukhin, A. B.; Kuznetsov, A. I.; Novikov, S. M.;
2012-01-01
Optical properties of spherical gold particles with diameters of 150-650 nm (mesoparticles) are studied by reflectance spectroscopy. Particles are fabricated by laser-induced transfer of metallic droplets onto metal and dielectric substrates. Contributions of higher multipoles (beyond the quadrup...
An iterative method for spherical bounces
Buniy, Roman V
2016-01-01
We develop a new iterative method for finding approximate solutions for spherical bounces associated with the decay of the false vacuum in scalar field theories. The method works for any generic potential in any number of dimensions, contains Coleman's thin-wall approximation as its first iteration, and greatly improves its accuracy by including higher order terms.
Spherical Horn Array for Wideband Propagation Measurements
DEFF Research Database (Denmark)
Franek, Ondrej; Pedersen, Gert Frølund
2011-01-01
A spherical array of horn antennas designed to obtain directional channel information and characteristics is introduced. A dual-polarized quad-ridged horn antenna with open flared boundaries and coaxial feeding for the frequency band 600 MHz–6 GHz is used as the element of the array. Matching...
Spherical polymer brushes under good solvent conditions
DEFF Research Database (Denmark)
Lo Verso, Federica; Egorov, Sergei A.; Milchev, Andrey
2010-01-01
A coarse grained model for flexible polymers end-grafted to repulsive spherical nanoparticles is studied for various chain lengths and grafting densities under good solvent conditions by molecular dynamics methods and density functional theory. With increasing chain length, the monomer density...
Realizability of stationary spherically symmetric transonic accretion
Ray, A K; Ray, Arnab K.
2002-01-01
The spherically symmetric stationary transonic (Bondi) flow is considered a classic example of an accretion flow. This flow, however, is along a separatrix, which is usually not physically realizable. We demonstrate, using a pedagogical example, that it is the dynamics which selects the transonic flow.
Sparse acoustic imaging with a spherical array
DEFF Research Database (Denmark)
Fernandez Grande, Efren; Xenaki, Angeliki
2015-01-01
proposes a plane wave expansion method based on measurements with a spherical microphone array, and solved in the framework provided by Compressed Sensing. The proposed methodology results in a sparse solution, i.e. few non-zero coefficients, and it is suitable for both source localization and sound field...
Compressive sensing with a spherical microphone array
DEFF Research Database (Denmark)
Fernandez Grande, Efren; Xenaki, Angeliki
2016-01-01
A wave expansion method is proposed in this work, based on measurements with a spherical microphone array, and formulated in the framework provided by Compressive Sensing. The method promotes sparse solutions via ‘1-norm minimization, so that the measured data are represented by few basis functions...
Programmable shape transformation of elastic spherical domes.
Abdullah, Arif M; Braun, Paul V; Hsia, K Jimmy
2016-07-20
We investigate mismatch strain driven programmable shape transformation of spherical domes and report the effects of different geometric and structural characteristics on dome behavior in response to applied mismatch strain. We envision a bilayer dome design where the differential swelling of the inner layer with respect to the passive outer layer in response to changes in dome surroundings (such as the introduction of an organic solvent) introduces mismatch strain within the bilayer system and causes dome shape transformation. Finite element analysis reveals that, in addition to snap-through, spherical domes undergo bifurcation buckling and eventually gradual bending to morph into cylinders with increasing mismatch strain. Besides demonstrating how the snap-through energy barrier depends on the spherical dome shape, our analysis identifies three distinct groups of dome geometries based on their mismatch strain-transformed configuration relationships. Our experiments with polymer-based elastic bilayer domes that exhibit differential swelling in organic solvents qualitatively confirm the finite element predictions. We establish that, in addition to externally applied stimuli (mismatch strain), bilayer spherical dome morphing can be tuned and hence programmed through its geometry and structural characteristics. Incorporation of an elastic instability mechanism such as snap-through within the framework of stimuli-responsive functional devices can improve their response time which is otherwise controlled by diffusion. Hence, our proposed design guidelines can be used to realize deployable, multi-functional, reconfigurable, and therefore, adaptive structures responsive to a diverse set of stimuli across multiple length scales.
Brain injuries caused by spherical bolts.
Roth, Jonathan; Mayo, Ami; Elran, Hanoch; Razon, Nissim; Kluger, Yoram
2005-05-01
Metallic particles contained in antihuman bombs increase the number of fatalities. The ballistics of these particles depends on the explosive that is used, the distance from the explosion, the shape of the particle projected, and the biomechanics of the injured tissue. The authors present their experience with penetrating spherical bolt injuries to the brain. The authors retrospectively reviewed clinical and radiological data obtained in eight patients with penetrating spherical bolt injuries to the cranium: four had Glasgow Coma Scale (GCS) scores less than 8 (three died, one from an unrelated injury) and four had a GCS score of 15 (all survived). Two of the latter patients suffered unique anatomical injuries attributed to the distinctive ballistics of spherical bolts: in one patient the bolt penetrated the cavernous sinus causing minimal cranial nerve injury, and in the other patient the bolt lodged in the fourth ventricle causing acute hydrocephalus without other neurological deficits. Penetrating spherical bolts to the brain may be lethal. Nevertheless, they have unique ballistics that cause highly delineated anatomical damage and minor neurological deficits.
Collapsing spherical null shells in general relativity
Directory of Open Access Journals (Sweden)
S Khakshournia
2011-03-01
Full Text Available In this work, the gravitational collapse of a spherically symmetric null shell with the flat interior and a charged Vaidya exterior spacetimes is studied. There is no gravitational impulsive wave present on the null hypersurface which is shear-free and contracting. It follows that there is a critical radius at which the shell bounces and starts expanding.
The glass transition of hard spherical colloids
Energy Technology Data Exchange (ETDEWEB)
Pusey, P.N. (Royal Signals and Radar Establishment, Malvern (UK)); Van Megen, W. (Royal Melbourne Inst. of Tech. (Australia). Dept. of Applied Physics)
1990-03-01
When suspended in a liquid, hard spherical colloidal particles can show fluid, crystalline and glassy phases. A light scattering study of the dynamics of the metastable fluid and glassy phases is reported. Comparison is made with the predictions of mode-coupling theories applied to the glass transition of simple atomic systems. (orig.).
Fluidization of non-spherical particles: Sphericity, Zingg factor and other fluidization parameters
Institute of Scientific and Technical Information of China (English)
Baiqian Liu; Xiaohui Zhang; Ligang Wang; Hui Hong
2008-01-01
A comparison of sphericity and Zingg factor for particle morphology and description of fluidized-bed dynamics are presented. It is found that Zingg factor Fz =LHIB2 (where L, H and B are, respectively, the length, breadth and height of a particle) well describes the effect of particle morphology. Experimental results show that non-spherical particles give poor fluidizing quality as compared to spherical particles in terms of pressure drop, Umf, etc. With the same volume-equivalent diameter, non-spherical particles have lower Umf and fluidizing coefficient δ. Some smooth curves have been obtained between the parameters δ Umf and Fz. The quality of fluidization could be evaluated by fluidizing coefficient, which has been correlated to the Zingg factor and minimum fluidizing velocity in this paper.
论兽面纹玉琮的艺术本质%On the Art Essence of the Beast Face Jade Cong
Institute of Scientific and Technical Information of China (English)
邓健铭
2013-01-01
The essence of the art of research and exploration , from ancient Greece to Platon at the beginning of the twentieth Century Freud;from Qu Yuan's “Lisao” to Zong Bing's “landscape painting , the” Wang Wei's “Syria painting” , has not stopped . Now we think that the essence of art is to visualize the means to create the appreciation to produce utilitarian mentality and self confirmation of the virtual world . Collection of Hubei Provincial Museum Ceng Houyi tomb unearthed jade Cong animal motifs , as grave goods , its unearthed time , material , shape , function and artistic value , giving it a unique aesthetic essence . The essence of art study provides complete and concrete object and is of great important role and significance .%对于艺术本质的研究与探索，从古希腊的柏拉图到20世纪初的弗洛伊德；从屈原的《离骚》到宗炳的《画山水述》、王微的《叙画》，一直就没有停留过。当下我们认为艺术的本质是以形象化的手段营造的让欣赏者产生非功利心态并进而自我确证的虚拟世界。湖北省博物馆馆藏曾侯乙墓出土的兽面纹玉琮，作为陪葬品，其出土的年代、材质、造型、功能及艺术价值，赋予它独特的审美本质。这对于艺术本质的研究提供了完整且形象具体的实物，有着重要的十分重要的作用和意义。
Asgharinejad, A.; Askari, H. R.
2016-09-01
In this paper, electromagnetically induced transparency (EIT) is investigated in a GaAs spherical quantum dot (SQD) with central potential in presence of spherical metallic nanoparticle (SMNP). Solving the Schrödinger equation in effective mass, eigenfunctions and eigenvalues of SQD are obtained. By using the obtained eigenfunctions and eigenvalues, the susceptibility of SQD is found. In addition, dependence of EIT on radius of SQD and SMNP, distance between SMNP and SQD and Rabi and probe frequencies are investigated.
What is the spacetime of {\\em physically realizable} spherical collapse?
Wagh, S M; Govinder, K S; Wagh, Sanjay M.; Saraykar, Ravindra V.; Govinder, Keshlan S.
2002-01-01
We argue that a particular spacetime, a spherically symmetric spacetime with hyper-surface orthogonal, radial, homothetic Killing vector, is a physically meaningful spacetime that describes the problem of spherical gravitational collapse in its full "physical" generality.
Theoretical study on spherical proton emission
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
The proton radioactivity half-lives of spherical proton emitters are investigated within a generalized liquid drop model(GLDM),including the proximity effects between nuclei in a neck and the mass and charge asymmetry.The penetrability is calculated in the WKB approximation and the assault frequency is estimated by the quantum mechanism method considering the structure of the parent nucleus.The spectroscopic factor is taken into account in half-life calculation,which is obtained by employing the relativistic mean field(RMF) theory.The half-lives within the GLDM are compared with the experimental data and other theoretical values.The results show that the GLDM works quite well for spherical proton emitters when the assault frequency is estimated by the quantum mechanical method and the spectroscopic factor is considered.
Colloidal cholesteric liquid crystal in spherical confinement
Li, Yunfeng; Jun-Yan Suen, Jeffrey; Prince, Elisabeth; Larin, Egor M.; Klinkova, Anna; Thérien-Aubin, Héloïse; Zhu, Shoujun; Yang, Bai; Helmy, Amr S.; Lavrentovich, Oleg D.; Kumacheva, Eugenia
2016-08-01
The organization of nanoparticles in constrained geometries is an area of fundamental and practical importance. Spherical confinement of nanocolloids leads to new modes of packing, self-assembly, phase separation and relaxation of colloidal liquids; however, it remains an unexplored area of research for colloidal liquid crystals. Here we report the organization of cholesteric liquid crystal formed by nanorods in spherical droplets. For cholesteric suspensions of cellulose nanocrystals, with progressive confinement, we observe phase separation into a micrometer-size isotropic droplet core and a cholesteric shell formed by concentric nanocrystal layers. Further confinement results in a transition to a bipolar planar cholesteric morphology. The distribution of polymer, metal, carbon or metal oxide nanoparticles in the droplets is governed by the nanoparticle size and yields cholesteric droplets exhibiting fluorescence, plasmonic properties and magnetic actuation. This work advances our understanding of how the interplay of order, confinement and topological defects affects the morphology of soft matter.
Theoretical study on spherical proton emission
Institute of Scientific and Technical Information of China (English)
ZHANG HongFei; WANG YongJia; DONG JianMin; LI JunQing
2009-01-01
The proton radioactivity half-lives of spherical proton emitters are investigated within a generalized liquid drop model (GLDM),including the proximity effects between nuclei in a neck and the mass and charge asymmetry.The penetrability is calculated in the WKB approximation and the assault frequency is estimated by the quantum mechanism method considering the structure of the parent nucleus.The spectroscopic factor is taken into account in half-life calculation,which is obtained by employing the relativistic mean field (RMF) theory.The half-lives within the GLDM are compared with the experimental data and other theoretical values.The results show that the GLDM works quite well for spherical proton emitters when the assault frequency is estimated by the quantum mechanical method and the spectroscopic factor is considered.
Spontaneous spherical symmetry breaking in atomic confinement
Sveshnikov, Konstantin; Tolokonnikov, Andrey
2017-07-01
The effect of spontaneous breaking of initial SO(3) symmetry is shown to be possible for an H-like atom in the ground state, when it is confined in a spherical box under general boundary conditions of "not going out" through the box surface (i.e. third kind or Robin's ones), for a wide range of physically reasonable values of system parameters. The most novel and nontrivial result, which has not been reported previously, is that such an effect takes place not only for attractive, but also for repulsive interactions of atomic electrons with the cavity environment. Moreover, in the limit of a large box size R ≫ aB the regime of an atom, soaring over a plane with boundary condition of "not going out", is reproduced, rather than a spherically symmetric configuration, which would be expected on the basis of the initial SO(3) symmetry of the problem.
Spherical projections and liftings in geometric tomography
DEFF Research Database (Denmark)
Goodey, Paul; Kiderlen, Markus; Weil, Wolfgang
2011-01-01
We consider a variety of integral transforms arising in Geometric Tomography. It will be shown that these can be put into a common framework using spherical projection and lifting operators. These operators will be applied to support functions and surface area measures of convex bodies and to rad......We consider a variety of integral transforms arising in Geometric Tomography. It will be shown that these can be put into a common framework using spherical projection and lifting operators. These operators will be applied to support functions and surface area measures of convex bodies...... and to radial functions of star bodies. We then investigate averages of lifted projections and show that they correspond to self-adjoint intertwining operators. We obtain formulas for the eigenvalues of these operators and use them to ascertain circumstances under which tomographic measurements determine...... the original bodies. This approach via mean lifted projections leads us to some unexpected relationships between seemingly disparate geometric constructions....
Spherical silicon micromirrors bent by anodic bonding.
Wu, Tong; Yamasaki, Takahiro; Hokari, Ryohei; Hane, Kazuhiro
2011-06-06
We propose here a novel and stable method for fabricating spherical micromirror by bonding a flat freestanding single-crystal-silicon (SCS) membrane with a fulcrum on a glass substrate. Smooth convex spherical surface is achieved inside the fulcrum by the bending moment generated in the circumference of the SCS membrane. The surface profiles fit well with parabolic curves within 36nm RMS error indicating a good optical performance. By modifying the diameter of the fulcrum, we also demonstrate that it is possible to fabricate micromirrors with a wide range of focal length (0.4mm-1.6mm). The fabricated micromirrors are also used as the mold for replication of micro polymeric lenses. The surface profiles of the micromirrors are transferred to the polymeric replica with a high accuracy.
Neutron spectroscopy with the Spherical Proportional Counter
Bougamont, E; Derre, J; Galan, J; Gerbier, G; Giomataris, I; Gros, M; Katsioulas, I; Jourde, D; Magnier, P; Navick, X F; Papaevangelou, T; Savvidis, I; Tsiledakis, G
2015-01-01
A novel large volume spherical proportional counter, recently developed, is used for neutron measurements. Gas mixtures of $N_{2}$ with $C_{2}H_{6}$ and pure $N_{2}$ are studied for thermal and fast neutron detection, providing a new way for the neutron spectroscopy. The neutrons are detected via the ${}^{14}N(n, p)C^{14}$ and ${}^{14}N(n, \\alpha)B^{11}$ reactions. Here we provide studies of the optimum gas mixture, the gas pressure and the most appropriate high voltage supply on the sensor of the detector in order to achieve the maximum amplification and better resolution. The detector is tested for thermal and fast neutrons detection with a ${}^{252}Cf$ and a ${}^{241}Am-{}^{9}Be$ neutron source. The atmospheric neutrons are successfully measured from thermal up to several MeV, well separated from the cosmic ray background. A comparison of the spherical proportional counter with the current available neutron counters is also given.
Constructive spherical codes near the Shannon bound
Solé, Patrick
2011-01-01
Shannon gave a lower bound in 1959 on the binary rate of spherical codes of given minimum Euclidean distance $\\rho$. Using nonconstructive codes over a finite alphabet, we give a lower bound that is weaker but very close for small values of $\\rho$: The construction is based on the Yaglom map combined with some finite sphere packings obtained from nonconstructive codes for the Euclidean metric. Concatenating geometric codes meeting the TVZ bound with a Lee metric BCH code over GF(p); we obtain spherical codes that are polynomial time constructible. Their parameters outperform those obtained by Lachaud and Stern in 1994. At very high rate they are above 98 per cent of the Shannon bound.
Quality metric for spherical panoramic video
Zakharchenko, Vladyslav; Choi, Kwang Pyo; Park, Jeong Hoon
2016-09-01
Virtual reality (VR)/ augmented reality (AR) applications allow users to view artificial content of a surrounding space simulating presence effect with a help of special applications or devices. Synthetic contents production is well known process form computer graphics domain and pipeline has been already fixed in the industry. However emerging multimedia formats for immersive entertainment applications such as free-viewpoint television (FTV) or spherical panoramic video require different approaches in content management and quality assessment. The international standardization on FTV has been promoted by MPEG. This paper is dedicated to discussion of immersive media distribution format and quality estimation process. Accuracy and reliability of the proposed objective quality estimation method had been verified with spherical panoramic images demonstrating good correlation results with subjective quality estimation held by a group of experts.
Flow past a porous approximate spherical shell
Srinivasacharya, D.
2007-07-01
In this paper, the creeping flow of an incompressible viscous liquid past a porous approximate spherical shell is considered. The flow in the free fluid region outside the shell and in the cavity region of the shell is governed by the Navier Stokes equation. The flow within the porous annulus region of the shell is governed by Darcy’s Law. The boundary conditions used at the interface are continuity of the normal velocity, continuity of the pressure and Beavers and Joseph slip condition. An exact solution for the problem is obtained. An expression for the drag on the porous approximate spherical shell is obtained. The drag experienced by the shell is evaluated numerically for several values of the parameters governing the flow.
Spherical Helices for Resonant Wireless Power Transfer
Directory of Open Access Journals (Sweden)
Maja Škiljo
2013-01-01
Full Text Available The capabilities of electrically small spherical helical antennas for wireless power transmission at small and moderate distances are analyzed. Influence of design on antenna radiation resistance, efficiency, and mode ratio is examined. These are the factors that, according to the theoretical considerations depicted herein, govern the maximum transfer performances. Various designs and configurations are considered for the purpose, with accent on small-size receivers suitable for implementation in powering common-sized gadgets. It is shown that spherical helix design is easily manipulated to achieve a reduced antenna size. Good radiation characteristics and impedance match are maintained by multiple-arm folded antenna design and by adjusting the separation between the arms.
Spherical Needlets for CMB Data Analysis
Marinucci, D; Balbi, A; Baldi, P; Cabella, P; Kerkyacharian, G; Natoli, P; Picard, D; Vittorio, N
2007-01-01
We discuss Spherical Needlets and their properties. Needlets are a form of spherical wavelets which do not rely on any kind of tangent plane approximation and enjoy good localization properties in both pixel and harmonic space; moreover needlets coefficients are asymptotically uncorrelated at any fixed angular distance, which makes their use in statistical procedures very promising. In view of these properties, we believe needlets may turn out to be especially useful in the analysis of Cosmic Microwave Background (CMB) data on the incomplete sky, as well as of other cosmological observations. As a final advantage, we stress that the implementation of needlets is computationally very convenient and may rely completely on standard data analysis packages such as HEALPix.
Spherically Symmetric, Self-Similar Spacetimes
Wagh, S M; Wagh, Sanjay M.; Govinder, Keshlan S.
2001-01-01
Self-similar spacetimes are of importance to cosmology and to gravitational collapse problems. We show that self-similarity or the existence of a homothetic Killing vector field for spherically symmetric spacetimes implies the separability of the spacetime metric in terms of the co-moving coordinates and that the metric is, uniquely, the one recently reported in [cqg1]. The spacetime, in general, has non-vanishing energy-flux and shear. The spacetime admits matter with any equation of state.
Modeling of thermal processes in spherical area
Demyanchenko, O.; Lyashenko, V.
2016-10-01
In this paper a mathematical model of the temperature field in spherical area with complex conditions of heat exchange with the environment is considered. The solution of the nonlinear initial boundary value problem is reduced to the solution of the nonlinear integral equation of Fredholm type respect to spatial coordinates and Volterra with the kernel in the form of the Green's function on the time coordinate.
Survival probability for open spherical billiards
Dettmann, Carl P.; Rahman, Mohammed R.
2014-12-01
We study the survival probability for long times in an open spherical billiard, extending previous work on the circular billiard. We provide details of calculations regarding two billiard configurations, specifically a sphere with a circular hole and a sphere with a square hole. The constant terms of the long-time survival probability expansions have been derived analytically. Terms that vanish in the long time limit are investigated analytically and numerically, leading to connections with the Riemann hypothesis.
Precursory singularities in spherical gravitational collapse
Lake, Kayll
1992-05-01
General conditions are developed for the formation of naked precursory ('shell-focusing') singularities in spherical gravitational collapse. These singularities owe their nakedness to the fact that the gravitational potential fails to be single valued prior to the onset of a true gravitational singularity. It is argued that they do not violate the spirit of cosmic censorship. Rather, they may well be an essentially generic feature of relativistic gravitational collapse.
The electromagnetic Casimir effect of spherical cavity
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
The Casimir effect results from the zero-point energy of vacuum. A spherical cavity can be divided into three regions, and we make an analysis of every region and then give a formal solution of Casimir energy. The zeta-function regularization is also used to dispel the divergence of the summation. At the end, we can see the Casimir effect of a single sphere is included in our results.
Bayesian variable selection with spherically symmetric priors
De Kock, M. B.; Eggers, H. C.
2014-01-01
We propose that Bayesian variable selection for linear parametrisations with Gaussian iid likelihoods be based on the spherical symmetry of the diagonalised parameter space. Our r-prior results in closed forms for the evidence for four examples, including the hyper-g prior and the Zellner-Siow prior, which are shown to be special cases. Scenarios of a single variable dispersion parameter and of fixed dispersion are studied, and asymptotic forms comparable to the traditional information criter...
Capillary condensation for fluids in spherical cavities
Urrutia, Ignacio; Szybisz, Leszek
2005-01-01
The capillary condensation for fluids into spherical nano-cavities is analyzed within the frame of two theoretical approaches. One description is based on a widely used simplified version of the droplet model formulated for studying atomic nuclei. The other, is a more elaborated calculation performed by applying a density functional theory. The agreement between both models is examined and it is shown that a small correction to the simple fluid model improves the predictions. A connection to ...
Interpolating Spherical Harmonics for Computing Antenna Patterns
2011-07-01
the specific radon-transform algorithms of ISAR. 28 References [1] Arfken , George [1970] Mathematical Methods for Physicists, second edi- tion...approximation methods . Section 2 sets out two antenna patterns to be tested in the spline algorithm. Section 3 reviews the spherical harmonic functions Y mn...number of samples on the sphere [12]. This compressed sensing result will not reduce the method of moment computations. All the current must be
Thermal deformations of a glass spherical satellite
Vasiliev, V. P.; Nenadovich, V. D.; Murashkin, V. V.; Sokolov, A. L.
2016-09-01
The effect of the kind of the reflecting coating of a glass spherical satellite on thermal deformations caused by the solar irradiation is considered. Two types of coating deposited on one of the hemispheres are considered: aluminum with a protective layer of bakelite varnish and interference dielectric coating for two orientations of the satellite orbit. Structures of a multilayer dielectric coating and technologies of its deposition are described.
Spherical Cancer Models in Tumor Biology
Directory of Open Access Journals (Sweden)
Louis-Bastien Weiswald
2015-01-01
Full Text Available Three-dimensional (3D in vitro models have been used in cancer research as an intermediate model between in vitro cancer cell line cultures and in vivo tumor. Spherical cancer models represent major 3D in vitro models that have been described over the past 4 decades. These models have gained popularity in cancer stem cell research using tumorospheres. Thus, it is crucial to define and clarify the different spherical cancer models thus far described. Here, we focus on in vitro multicellular spheres used in cancer research. All these spherelike structures are characterized by their well-rounded shape, the presence of cancer cells, and their capacity to be maintained as free-floating cultures. We propose a rational classification of the four most commonly used spherical cancer models in cancer research based on culture methods for obtaining them and on subsequent differences in sphere biology: the multicellular tumor spheroid model, first described in the early 70s and obtained by culture of cancer cell lines under nonadherent conditions; tumorospheres, a model of cancer stem cell expansion established in a serum-free medium supplemented with growth factors; tissue-derived tumor spheres and organotypic multicellular spheroids, obtained by tumor tissue mechanical dissociation and cutting. In addition, we describe their applications to and interest in cancer research; in particular, we describe their contribution to chemoresistance, radioresistance, tumorigenicity, and invasion and migration studies. Although these models share a common 3D conformation, each displays its own intrinsic properties. Therefore, the most relevant spherical cancer model must be carefully selected, as a function of the study aim and cancer type.
Gravitational collapse of barotropic spherical fluids
Giambo, R; Magli, G; Piccione, P; Giambo', Roberto; Giannoni, Fabio; Magli, Giulio; Piccione, Paolo
2003-01-01
The gravitational collapse of spherical, barotropic perfect fluids is analyzed here. For the first time, the final state of these systems is characterized without resorting to simplifying assumptions - such as self-similarity - using a new approach based on non-linear o.d.e. techniques. Formation of naked singularities is shown to occur for solutions such that the mass function is sufficiently regular in a neighborhood of the spacetime singularity.
New mathematical framework for spherical gravitational collapse
Giambo, R; Magli, G; Piccione, P; Giambo', Roberto; Giannoni, Fabio; Magli, Giulio; Piccione, Paolo
2003-01-01
A theorem, giving necessary and sufficient condition for naked singularity formation in spherically symmetric non static spacetimes under hypotheses of physical acceptability, is formulated and proved. The theorem relates existence of singular null geodesics to existence of regular curves which are super-solutions of the radial null geodesic equation, and allows us to treat all the known examples of naked singularities from a unified viewpoint. New examples are also found using this approach, and perspectives are discussed.
New mathematical framework for spherical gravitational collapse
Energy Technology Data Exchange (ETDEWEB)
Giambo, Roberto [Dipartimento di Matematica e Informatica, Universita di Camerino (Italy); Giannoni, Fabio [Dipartimento di Matematica e Informatica, Universita di Camerino (Italy); Magli, Giulio [Dipartimento di Matematica, Politecnico di Milano (Italy); Piccione, Paolo [Dipartimento di Matematica e Informatica, Universita di Camerino (Italy)
2003-03-21
A theorem, giving necessary and sufficient condition for naked singularity formation in spherically symmetric non-static spacetimes under hypotheses of physical acceptability, is formulated and proved. The theorem relates the existence of singular null geodesics to the existence of regular curves which are supersolutions of the radial null geodesic equation, and allows us to treat all the known examples of naked singularities from a unified viewpoint. New examples are also found using this approach, and perspectives are discussed. (letter to the editor)
Analysis of liquid bridge between spherical particles
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
A pair of central moving spherical particles connected by a pendular liquid bridge with interstitial Newtonian fluid is often encountered in pariculate coalescence process. In this paper, by assuming perfect-wet condition, the effects of liquid volume and separation distance on static liquid bridge are analyzed, and the relation between rupture energy and liquid bridge volume is also studied. These points would be of significance in industrial processes related to adhesive particles.
Ultrasonic analysis of spherical composite test specimens
Energy Technology Data Exchange (ETDEWEB)
Brosey, W.D.
1984-08-22
Filament wound spherical test specimens have been examined ultrasonically as part of a program to determine the effectiveness of various nondestructive evaluation techniques for analysis of mechanical characteristics of a composite with enclosed geometry. The Kevlar-epoxy composite specimens contained simulated defect conditions which were located, and the extent of damage determined, using ultrasonic analysis. Effects of transducer frequency and signal parameters have been examined to determine optimum conditions for flaw detection. The data were displayed in rectangular and axonometric projection.
Effects of coating spherical iron oxide nanoparticles
2016-01-01
International audience; We investigate the effect of several coatings applied in biomedical applications to iron oxide nanoparticles on the size, structure and composition of the particles. The four structural techniques employed – TEM, DLS, VSM, SAXS and EXAFS – show no significant effects of the coatings on the spherical shape of the bare nanoparticles, the average sizes or the local order around the Fe atoms. The NPs coated with hydroxylmethylene bisphosphonate or catechol have a lower pro...
Resonating properties of passive spherical optical microcavities
Institute of Scientific and Technical Information of China (English)
Wen Li(李文); Ruopeng Wang(王若鹏)
2004-01-01
As an optically pumped device, the lasing characteristics of a spherical microcavity laser depend on the optical pumping processes. These characteristics can be described in term of the Q factor and the optical field distribution in a microsphere. We derived analytical expressions and carried out numerical calculation for Q factor and optical field. The Q factor is found to be oscillatory functions of the radius of a microsphere and the pumping wavelength, and the pumping efficiency for a resonating microsphere is much higher than that for an anti-resonating microsphere. Using tunable lasers as pumping sources is suggested in order to achieve a higher pumping efficiency. Numerical calculation on optical field distribution in spherical microcavities shows that a well focused Gaussian beam is a suitable incident wave for cavity quantum electrodynamics experiments in which strong confinement of optical field in the center of a microsphere is requested, but higher order spherical wave should be used instead for exciting whispering-gallery-mode (WGM) microsphere lasers, for the purpose of favoring optical energy transferring to WGM in optical microspheres.
Earth Sphericity Effects on Subduction Morphology
Morra, G.; Chatelain, P.; Tackley, P.; Koumoutsakos, P.
2007-12-01
We present here the first application in Geodynamics of a Multipole accelerated Boundary Element Method (FMM- BEM) for Stokes Flow. The approach offers the advantage of a reduced number of computational elements and linear scaling with the problem size. We show that this numerical mehod can be fruitfully applied to the simulation of several geodynamic systems at the planetary scale in spheical coordinates and we suggest a general appraoch for modeling combined mantle convection and plate tectonics. The potentialities of the approach are shown investigating the effect played by Earth sphericity on the subduction of a very wide oceanic lithosphere , comparing the morphology of the subducted lithosphere in a spherical and in flat setting. The results show a striking difference between the two models: while the slab on a "flat Earth" shows slight undulation, the same subducting plate on a spherical Earth-like setting presents a distinct folding below the trench far from the edges, with wavelength of (1000km-2000km) as Pacific trenches.
Fusion potential for spherical and compact tokamaks
Energy Technology Data Exchange (ETDEWEB)
Sandzelius, Mikael
2003-02-01
The tokamak is the most successful fusion experiment today. Despite this, the conventional tokamak has a long way to go before being realized into an economically viable power plant. In this master thesis work, two alternative tokamak configurations to the conventional tokamak has been studied, both of which could be realized to a lower cost. The fusion potential of the spherical and the compact tokamak have been examined with a comparison of the conventional tokamak in mind. The difficulties arising in the two configurations have been treated from a physical point of view concerning the fusion plasma and from a technological standpoint evolving around design, materials and engineering. Both advantages and drawbacks of either configuration have been treated relative to the conventional tokamak. The spherical tokamak shows promising plasma characteristics, notably a high {beta}-value but have troubles with high heat loads and marginal tritium breeding. The compact tokamak operates at a high plasma density and a high magnetic field enabling it to be built considerably smaller than any other tokamak. The most notable down-side being high heat loads and neutron transport problems. With the help of theoretical reactor studies, extrapolating from where we stand today, it is conceivable that the spherical tokamak is closer of being realized of the two. But, as this study shows, the compact tokamak power plant concept offers the most appealing prospect.
Spherical Layout Implementation using Centroidal Voronoi Tessellations
Larrea, Martin; Martig, Sergio; Castro, Silvia
2009-01-01
The 3D tree visualization faces multiple challenges: the election of an appropriate layout, the use of the interactions that make the data exploration easier and a metaphor that helps in the process of information understanding. A good combination of these elements will result in a visualization that effectively conveys the key features of a complex structure or system to a wide range of users and permits the analytical reasoning process. In previous works we presented the Spherical Layout, a technique for 3D tree visualization that provides an excellent base to achieve those key features. The layout was implemented using the TriSphere algorithm, a method that discretized the spheres's surfaces with triangles to achieve a uniform distribution of the nodes. The goal of this work was centered in a new algorithm for the implementation of the Spherical layout; we called it the Weighted Spherical Centroidal Voronoi Tessellations (WSCVT). In this paper we present a detailed description of this new implementation an...
Scaling Relationships for Spherical Polymer Brushes Revisited.
Chen, Guang; Li, Hao; Das, Siddhartha
2016-06-16
In this short paper, we revisit the scaling relationships for spherical polymer brushes (SPBs), i.e., polymer brushes grafted to rigid, spherical particles. Considering that the brushes can be described to be encased in a series of hypothetical spherical blobs, we identify significant physical discrepancies in the model of Daoud and Cotton (Journal of Physics, 1982), which is considered to be the state of the art in scaling modeling of SPBs. We establish that the "brush" configuration of the polymer molecules forming the SPBs is possible only if the swelling ratio (which is the ratio of the end-to-end length of the blob-encased polymer segment to the corresponding coil-like polymer segment) is always less than unity-a notion that has been erroneously overlooked in the model of Daoud and Cotton. We also provide new scaling arguments that (a) establish this swelling (or more appropriately shrinking) ratio as a constant (less than unity) for the case of "good" solvent, (b) recover the scaling predictions for blob dimension and monomer number and monomer concentration distributions within the blob, and
Encounters between spherical galaxies - II. Systems with a dark halo
Gonzalez-Garcia, AC; van Albada, TS
2005-01-01
We perform N-body simulations of encounters between spherical systems surrounded by a spherical halo. Following a preceding paper with a similar aim, the initial systems include a spherical Jaffe model for the luminous matter and a Hernquist model for the halo. The merger remnants from this sample a
PENETRATION OF A SOUND FIELD THROUGH A MULTILAYERED SPHERICAL SHELL
Directory of Open Access Journals (Sweden)
G. Ch. Shushkevich
2013-01-01
Full Text Available An analytical solution of the boundary problem describing the process of penetration of thesound field of a spherical emitter located inside a thin unclosed spherical shell through a permeable multilayered spherical shell is considered. The influence of some parameters of the problem on the value of the sound field weakening (screening coefficient is studied via a numerical simulation.
Larose, Daniel
2016-01-01
Contrairement à la majorité des interprètes du Timée de Platon, nous ne croyons pas que la figure du démiurge représente réellement une cause productrice. Ce type de causalité, explicitement attribué au νοῦς dans le Phédon, ne peut, selon nous, être associé qu’à l’activité de l’âme du monde et des dieux de la tradition. Le démiurge joue un autre rôle. Représentant le meilleur des êtres intelligibles éternels (37a), un dieu éternel (34a), le démiurge ne peut, à ce titre, être un principe de mo...
Addition theorems for spin spherical harmonics: II. Results
Energy Technology Data Exchange (ETDEWEB)
Bouzas, Antonio O, E-mail: abouzas@mda.cinvestav.mx [Departamento de Fisica Aplicada, CINVESTAV-IPN, Carretera Antigua a Progreso Km. 6, Apdo. Postal 73 ' Cordemex' , Merida 97310, Yucatan (Mexico)
2011-04-22
Based on the results of part I (2011 J. Phys. A: Math. Theor. 44 165301), we obtain the general form of the addition theorem for spin spherical harmonics and give explicit results in the cases involving one spin-s' and one spin-s spherical harmonics with s', s = 1/2, 1, 3/2, and |s' - s| = 0, 1. We also obtain a fully general addition theorem for one scalar and one tensor spherical harmonic of arbitrary rank. A variety of bilocal sums of ordinary and spin spherical harmonics are given in explicit form, including a general explicit expression for bilocal spherical harmonics.
Watermarking on 3D mesh based on spherical wavelet transform
Institute of Scientific and Technical Information of China (English)
金剑秋; 戴敏雅; 鲍虎军; 彭群生
2004-01-01
In this paper we propose a robust watermarking algorithm for 3D mesh. The algorithm is based on spherical wavelet transform. Our basic idea is to decompose the original mesh into a series of details at different scales by using spherical wavelet transform; the watermark is then embedded into the different levels of details. The embedding process includes: global sphere parameterization, spherical uniform sampling, spherical wavelet forward transform, embedding watermark, spherical wavelet inverse transform, and at last resampling the mesh watermarked to recover the topological connectivity of the original model. Experiments showed that our algorithm can improve the capacity of the watermark and the robustness of watermarking against attacks.
Lott, Debra
2007-01-01
This article describes a project with a transformative approach to color theory and still life. Students' use of an arbitrary color scheme can open their eyes, push their creativity and produce exciting paintings. Ordinary still-life objects will be transformed into dramatic, vibrant visuals. The Fauve style of painting is a great art history…
Morphogenesis of membrane invaginations in spherical confinement
Kahraman, Osman; Mueller, Martin Michael
2012-01-01
We study the morphology of a fluid membrane in spherical confinement. When the area of the membrane is slightly larger than the area of the outer container, a single axisymmetric invagination is observed. For higher area self-contact occurs; the invagination breaks symmetry and deforms into an ellipsoid-like shape connected to its outer part via a small slit. For even higher areas an invagination forms inside the original invagination. The folding patterns observed could constitute basic building blocks in the morphogenesis of biological tissues and organelles.
Inversion of band patterns in spherical tumblers.
Chen, Pengfei; Lochman, Bryan J; Ottino, Julio M; Lueptow, Richard M
2009-04-10
Bidisperse granular mixtures in spherical tumblers segregate into three bands: one at each pole and one at the equator. For low fill levels, large particles are at the equator; for high fill levels, the opposite occurs. Segregation is robust, though the transition depends on fill level, particle size, and rotational speed. Discrete element method simulations reproduce surface patterns and reveal internal structures. Particle trajectories show that small particles flow farther toward the poles than large particles in the upstream portion of the flowing layer for low fill levels leading to a band of small particles at each pole. The opposite occurs for high fill levels, though more slowly.
Spherical solitons in ion-beam plasma
Energy Technology Data Exchange (ETDEWEB)
Das, G.C.; Ibohanbi Singh, K. (Manipur Univ., Imphal (India). Dept. of Mathematics)
1991-01-01
By using the reductive perturbation technique, the soliton solution of an ion-acoustic wave radially ingoing in a spherically bounded plasma consisting of ions and ion-beams with multiple electron temperatures is obtained. In sequel to the earlier investigations, the solitary waves are studied as usual through the derivation of a modified Korteweg-de Vries (K-dV) equation in different plasma models arising due to the variation of the isothermality of the plasmas. The characteristics of the solitons are finally compared with those of the planar and the cylindrical solitons. (orig.).
The dynamo bifurcation in rotating spherical shells
Morin, Vincent; 10.1142/S021797920906378X
2010-01-01
We investigate the nature of the dynamo bifurcation in a configuration applicable to the Earth's liquid outer core, i.e. in a rotating spherical shell with thermally driven motions. We show that the nature of the bifurcation, which can be either supercritical or subcritical or even take the form of isola (or detached lobes) strongly depends on the parameters. This dependence is described in a range of parameters numerically accessible (which unfortunately remains remote from geophysical application), and we show how the magnetic Prandtl number and the Ekman number control these transitions.
The Spherical Bolometric Albedo of Planet Mercury
Mallama, Anthony
2017-01-01
Published reflectance data covering several different wavelength intervals has been combined and analyzed in order to determine the spherical bolometric albedo of Mercury. The resulting value of 0.088 +/- 0.003 spans wavelengths from 0 to 4 {\\mu}m which includes over 99% of the solar flux. This bolometric result is greater than the value determined between 0.43 and 1.01 {\\mu}m by Domingue et al. (2011, Planet. Space Sci., 59, 1853-1872). The difference is due to higher reflectivity at wavelen...
The Spherical Tokamak MEDUSA for Mexico
Ribeiro, C.; Salvador, M.; Gonzalez, J.; Munoz, O.; Tapia, A.; Arredondo, V.; Chavez, R.; Nieto, A.; Gonzalez, J.; Garza, A.; Estrada, I.; Jasso, E.; Acosta, C.; Briones, C.; Cavazos, G.; Martinez, J.; Morones, J.; Almaguer, J.; Fonck, R.
2011-10-01
The former spherical tokamak MEDUSA (Madison EDUcation Small Aspect.ratio tokamak, R Mexican Fusion Network. Strong liaison within national and international plasma physics communities is expected. New activities on plasma & engineering modeling are expected to be developed in parallel by using the existing facilities such as a multi-platform computer (Silicon Graphics Altix XE250, 128G RAM, 3.7TB HD, 2.7GHz, quad-core processor), ancillary graph system (NVIDIA Quadro FE 2000/1GB GDDR-5 PCI X16 128, 3.2GHz), and COMSOL Multiphysics-Solid Works programs.
Design of spherical symmetric gradient index lenses
Miñano, Juan C.; Grabovičkić, Dejan; Benítez, Pablo; González, Juan C.; Santamaría, Asunción
2012-10-01
Spherical symmetric refractive index distributions also known as Gradient Index lenses such as the Maxwell-Fish-Eye (MFE), the Luneburg or the Eaton lenses have always played an important role in Optics. The recent development of the technique called Transformation Optics has renewed the interest in these gradient index lenses. For instance, Perfect Imaging within the Wave Optics framework has recently been proved using the MFE distribution. We review here the design problem of these lenses, classify them in two groups (Luneburg moveable-limits and fixed-limits type), and establish a new design techniques for each type of problem.
Ergodicity and Gaussianity for Spherical Random Fields
Marinucci, Domenico
2009-01-01
We investigate the relationship between ergodicity and asymptotic Gaussianity of isotropic spherical random fields, in the high-resolution (or high-frequency) limit. In particular, our results suggest that under a wide variety of circumstances the two conditions are equivalent, i.e. the sample angular power spectrum may converge to the population value if and only if the underlying field is asymptotically Gaussian, in the high frequency sense. These findings may shed some light on the role of Cosmic Variance in Cosmic Microwave Background (CMB) radiation data analysis.
Polymer and spherical nanoparticle diffusion in nanocomposites
Karatrantos, Argyrios; Composto, Russell J.; Winey, Karen I.; Clarke, Nigel
2017-05-01
Nanoparticle and polymer dynamics in nanocomposites containing spherical nanoparticles were investigated by means of molecular dynamics simulations. We show that the polymer diffusivity decreases with nanoparticle loading due to an increase of the interfacial area created by nanoparticles, in the polymer matrix. We show that small sized nanoparticles can diffuse much faster than that predicted from the Stokes-Einstein relation in the dilute regime. We show that the nanoparticle diffusivity decreases at higher nanoparticle loading due to nanoparticle-polymer interface. Increase of the nanoparticle radius slows the nanoparticle diffusion.
Compressive sensing with a spherical microphone array.
Fernandez-Grande, Efren; Xenaki, Angeliki
2016-02-01
A wave expansion method is proposed in this work, based on measurements with a spherical microphone array, and formulated in the framework provided by Compressive Sensing. The method promotes sparse solutions via ℓ1-norm minimization, so that the measured data are represented by few basis functions. This results in fine spatial resolution and accuracy. This publication covers the theoretical background of the method, including experimental results that illustrate some of the fundamental differences with the "conventional" least-squares approach. The proposed methodology is relevant for source localization, sound field reconstruction, and sound field analysis.
Finite element modelingof spherical induction actuator
Galary, Grzegorz
2005-01-01
The thesis deals with finite element method simulations of the two-degree of freedom spherical induction actuator performed using the 2D and 3D models. In some cases non-linear magnetization curves, rotor movement and existence of higher harmonics are taken into account. The evolution of the model leading to its simplification is presented. Several rotor structures are tested, namely the one-layer, two-layers and two-layers-with-teeth rotor. The study of some rotor parameters, i.e. t...
Quantum Radiation of Uniformly Accelerated Spherical Mirrors
Frolov, V
2001-01-01
We study quantum radiation generated by a uniformly accelerated motion of small spherical mirrors. To obtain Green's function for a scalar massless field we use Wick's rotation. In the Euclidean domain the problem is reduced to finding an electric potential in 4D flat space in the presence of a metallic toroidal boundary. The latter problem is solved by a separation of variables. After performing an inverse Wick's rotation we obtain the Hadamard function in the wave-zone regime and use it to calculate the vacuum fluctuations and the vacuum expectation for the energy density flux in the wave zone.
Spherical Gravitating Systems of Arbitrary Dimension
Das, A
2001-01-01
We study spherically symmetric solutions to the Einstein field equations under the assumption that the space-time may possess an arbitrary number of spatial dimensions. The general solution of Synge is extended to describe systems of any dimension. Arbitrary dimension analogues of known four dimensional solutions are also presented, derived using the above scheme. Finally, we discuss the requirements for the existence of Birkhoff's theorems in space-times of arbitrary dimension with or without matter fields present. Cases are discussed where the assumptions of the theorem are considerably weakened yet the theorem still holds. We also discuss where the weakening of certain conditions may cause the theorem to fail.
Conservative interpolation between general spherical meshes
Directory of Open Access Journals (Sweden)
E. Kritsikis
2015-06-01
Full Text Available An efficient, local, explicit, second-order, conservative interpolation algorithm between spherical meshes is presented. The cells composing the source and target meshes may be either spherical polygons or longitude–latitude quadrilaterals. Second-order accuracy is obtained by piecewise-linear finite volume reconstruction over the source mesh. Global conservation is achieved through the introduction of a supermesh, whose cells are all possible intersections of source and target cells. Areas and intersections are computed exactly to yield a geometrically exact method. The main efficiency bottleneck caused by the construction of the supermesh is overcome by adopting tree-based data structures and algorithms, from which the mesh connectivity can also be deduced efficiently. The theoretical second-order accuracy is verified using a smooth test function and pairs of meshes commonly used for atmospheric modelling. Experiments confirm that the most expensive operations, especially the supermesh construction, have O(NlogN computational cost. The method presented is meant to be incorporated in pre- or post-processing atmospheric modelling pipelines, or directly into models for flexible input/output. It could also serve as a basis for conservative coupling between model components, e.g. atmosphere and ocean.
Conservative interpolation between general spherical meshes
Kritsikis, Evaggelos; Aechtner, Matthias; Meurdesoif, Yann; Dubos, Thomas
2017-01-01
An efficient, local, explicit, second-order, conservative interpolation algorithm between spherical meshes is presented. The cells composing the source and target meshes may be either spherical polygons or latitude-longitude quadrilaterals. Second-order accuracy is obtained by piece-wise linear finite-volume reconstruction over the source mesh. Global conservation is achieved through the introduction of a supermesh, whose cells are all possible intersections of source and target cells. Areas and intersections are computed exactly to yield a geometrically exact method. The main efficiency bottleneck caused by the construction of the supermesh is overcome by adopting tree-based data structures and algorithms, from which the mesh connectivity can also be deduced efficiently.The theoretical second-order accuracy is verified using a smooth test function and pairs of meshes commonly used for atmospheric modelling. Experiments confirm that the most expensive operations, especially the supermesh construction, have O(NlogN) computational cost. The method presented is meant to be incorporated in pre- or post-processing atmospheric modelling pipelines, or directly into models for flexible input/output. It could also serve as a basis for conservative coupling between model components, e.g., atmosphere and ocean.
Spontaneous spherical symmetry breaking in atomic confinement
Sveshnikov, K
2016-01-01
The effect of spontaneous breaking of initial SO(3) symmetry is shown to be possible for an H-like atom in the ground state, when it is confined in a spherical box under general boundary conditions of "not going out" through the box surface (i.e. third kind or Robin's ones), for a wide range of physically reasonable values of system parameters. The reason is that such boundary conditions could yield a large magnitude of electronic wavefunction in some sector of the box boundary, what in turn promotes atomic displacement from the box center towards this part of the boundary, and so the underlying SO(3) symmetry spontaneously breaks. The emerging Goldstone modes, coinciding with rotations around the box center, restore the symmetry by spreading the atom over a spherical shell localized at some distances from the box center. Atomic confinement inside the cavity proceeds dynamically -- due to the boundary condition the deformation of electronic wavefunction near the boundary works as a spring, that returns the at...
Spherical primary optical telescope (SPOT) segments
Hall, Christopher; Hagopian, John; DeMarco, Michael
2012-09-01
The spherical primary optical telescope (SPOT) project is an internal research and development program at NASA Goddard Space Flight Center. The goals of the program are to develop a robust and cost effective way to manufacture spherical mirror segments and demonstrate a new wavefront sensing approach for continuous phasing across the segmented primary. This paper focuses on the fabrication of the mirror segments. Significant cost savings were achieved through the design, since it allowed the mirror segments to be cast rather than machined from a glass blank. Casting was followed by conventional figuring at Goddard Space Flight Center. After polishing, the mirror segments were mounted to their composite assemblies. QED Technologies used magnetorheological finishing (MRF®) for the final figuring. The MRF process polished the mirrors while they were mounted to their composite assemblies. Each assembly included several magnetic invar plugs that extended to within an inch of the face of the mirror. As part of this project, the interaction between the MRF magnetic field and invar plugs was evaluated. By properly selecting the polishing conditions, MRF was able to significantly improve the figure of the mounted segments. The final MRF figuring demonstrates that mirrors, in the mounted configuration, can be polished and tested to specification. There are significant process capability advantes due to polishing and testing the optics in their final, end-use assembled state.
Initial assessments of ignition spherical torus
Energy Technology Data Exchange (ETDEWEB)
Peng, Y.K.M.; Borowski, S.K.; Bussell, G.T.; Dalton, G.R.; Gorker, G.E.; Haines, J.R.; Hamilton, W.R.; Kalsi, S.S.; Lee, V.D.; Miller, J.B.
1985-12-01
Initial assessments of ignition spherical tori suggest that they can be highly cost effective and exceptionally small in unit size. Assuming advanced methods of current drive to ramp up the plasma current (e.g., via lower hybrid wave at modest plasma densities and temperatures), the inductive solenoid can largely be eliminated. Given the uncertainties in plasma energy confinement times and the effects of strong paramagnetism on plasma pressure, and allowing for the possible use of high-strength copper alloys (e.g., C-17510, Cu-Ni-Be alloy), ignition spherical tori with a 50-s burn are estimated to have major radii ranging from 1.0 to 1.6 m, aspect ratios from 1.4 to 1.7, vacuum toroidal fields from 2 to 3 T, plasma currents from 10 to 19 MA, and fusion power from 50 to 300 MW. Because of its modest field strength and simple poloidal field coil configuration, only conventional engineering approaches are needed in the design. A free-standing toroidal field coil/vacuum vessel structure is assessed to be feasible and relatively independent of the shield structure and the poloidal field coils. This exceptionally simple configuration depends significantly, however, on practical fabrication approaches of the center conductor post, about which there is presently little experience. 19 refs.
Relativistic radiative transfer in relativistic spherical flows
Fukue, Jun
2017-02-01
Relativistic radiative transfer in relativistic spherical flows is numerically examined under the fully special relativistic treatment. We first derive relativistic formal solutions for the relativistic radiative transfer equation in relativistic spherical flows. We then iteratively solve the relativistic radiative transfer equation, using an impact parameter method/tangent ray method, and obtain specific intensities in the inertial and comoving frames, as well as moment quantities, and the Eddington factor. We consider several cases; a scattering wind with a luminous central core, an isothermal wind without a core, a scattering accretion on to a luminous core, and an adiabatic accretion on to a dark core. In the typical wind case with a luminous core, the emergent intensity is enhanced at the center due to the Doppler boost, while it reduces at the outskirts due to the transverse Doppler effect. In contrast to the plane-parallel case, the behavior of the Eddington factor is rather complicated in each case, since the Eddington factor depends on the optical depth, the flow velocity, and other parameters.
Preparation of nanoporous titania spherical nanoparticles
Shiba, Kota; Sato, Soh; Matsushita, Takayuki; Ogawa, Makoto
2013-03-01
Preparation of nanoporous titania particles from well-defined titania-octadecylamine (titania-ODA) hybrid spherical particles with 450 nm in size, which were prepared by the method reported previously (Chem. Commun., 2009, pp. 6851-6853 [39]; RSC Adv., 2012, vol. 2, pp. 1343-1349 [40]), was studied. ODA was removed by solvent extraction with acidic ethanol to obtain nanoporous titania particles and subsequent calcination led to the formation of nanoporous titania particles with the nanopore size ranging from 2 to 4 nm depending on the calcination temperature. The as-synthesized titania was amorphous and was transformed into anatase (at around 300 °C) and rutile (at around 600 °C) by the heat treatment. The phase transition behavior was discussed in comparison with that of as-synthesized titania-ODA particles without ODA removal. Spherical particles of titania-ODA hybrids with 70 nm in size were also transformed into nanoporous titania particles composed of anatase crystallites by the washing and calcination at 500 °C for 1 h.
Understanding pop-ins in spherical nanoindentation
Energy Technology Data Exchange (ETDEWEB)
Pathak, Siddhartha, E-mail: pathak@lanl.gov, E-mail: siddharthapathak@gmail.com [MPA-CINT Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Riesterer, Jessica L.; Michler, Johann [Empa, Swiss Federal Laboratory for Materials Testing and Research, Laboratory for Mechanics of Materials and Nanostructures, Feuerwerkerstrasse 39, Thun 3602 (Switzerland); Kalidindi, Surya R. [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)
2014-10-20
Pop-ins, or sudden displacement-bursts at constant load in a nanoindentation test, are typically attributed to the difficulty of setting up potent dislocation sources in the very small indentation zones in these experiments. Such displacement (and strain) bursts would intuitively indicate a sharp drop in stress during the pop-in event itself. However, spherical indentation stress-strain curves routinely exhibit a high and stable indentation stress value during the pop-in, and the indentation stresses decrease only after a further finite amount of additional indentation displacement has been applied. In order to understand this discrepancy, we utilize a combination of interrupted spherical indentation tests along with depth profiling of the residual indentation surfaces using in-situ atomic force microscopy (AFM) to study pop-ins. The AFM surface profile maps show that there is an asymmetric profile change over a limited region around the indentation contact area for a single pop-in; the asymmetry disappears upon further loading beyond the pop-in. A plausible sequence of physical processes (related to metal plasticity) occurring underneath the indenter during and immediately after the occurrence of the pop-in is proposed to explain these observations.
Saltation of Non-Spherical Sand Particles
Wang, Zhengshi; Ren, Shan; Huang, Ning
2014-01-01
Saltation is an important geological process and the primary source of atmospheric mineral dust aerosols. Unfortunately, no studies to date have been able to precisely reproduce the saltation process because of the simplified theoretical models used. For example, sand particles in most of the existing wind sand movement models are considered to be spherical, the effects of the sand shape on the structure of the wind sand flow are rarely studied, and the effect of mid-air collision is usually neglected. In fact, sand grains are rarely round in natural environments. In this paper, we first analyzed the drag coefficients, drag forces, and starting friction wind speeds of sand grains with different shapes in the saltation process, then established a sand saltation model that considers the coupling effect between wind and the sand grains, the effect of the mid-air collision of sand grains, and the effect of the sand grain shape. Based on this model, the saltation process and sand transport rate of non-spherical sand particles were simulated. The results show that the sand shape has a significant impact on the saltation process; for the same wind speed, the sand transport rates varied for different shapes of sand grains by as much as several-fold. Therefore, sand shape is one of the important factors affecting wind-sand movement. PMID:25170614
Rayleigh scattering of a spherical sound wave.
Godin, Oleg A
2013-02-01
Acoustic Green's functions for a homogeneous medium with an embedded spherical obstacle arise in analyses of scattering by objects on or near an interface, radiation by finite sources, sound attenuation in and scattering from clouds of suspended particles, etc. An exact solution of the problem of diffraction of a monochromatic spherical sound wave on a sphere is given by an infinite series involving products of Bessel functions and Legendre polynomials. In this paper, a simple, closed-form solution is obtained for scattering by a sphere with a radius that is small compared to the wavelength. Soft, hard, impedance, and fluid obstacles are considered. The solution is valid for arbitrary positions of the source and receiver relative to the scatterer. Low-frequency scattering is shown to be rather sensitive to boundary conditions on the surface of the obstacle. Low-frequency asymptotics of the scattered acoustic field are extended to transient incident waves. The asymptotic expansions admit an intuitive interpretation in terms of image sources and reduce to classical results in appropriate limiting cases.
Non-Spherical Models of Neutron Stars
Zubairi, O; Romero, A; Mellinger, R; Weber, F; Orsaria, M; Contrera, G
2015-01-01
Non-rotating neutron stars are generally treated in theoretical studies as perfect spheres. Such a treatment, however, may not be correct if strong magnetic fields are present (such as for magnetars) and/or the pressure of the matter in the cores of neutron stars is non-isotropic (e.g., color superconducting). In this paper, we investigate the structure of non-spherical neutron stars in the framework of general relativity. Using a parameterized metric to model non-spherical mass distributions, we first derive a stellar structure equation for deformed neutron stars. Numerical investigations of this model equation show that the gravitational masses of deformed neutron stars depend rather strongly on the degree and type (oblate or prolate) of stellar deformation. In particular, we find that the mass of a neutron star increases with increasing oblateness but decreases with increasing prolateness. If this feature carries over to a full two-dimensional treatment of deformed neutron stars, this opens up the possibil...
Spherically symmetric conformal gravity and "gravitational bubbles"
Berezin, V A; Eroshenko, Yu N
2016-01-01
The general structure of the spherically symmetric solutions in the Weyl conformal gravity is described. The corresponding Bach equation are derived for the special type of metrics, which can be considered as the representative of the general class. The complete set of the pure vacuum solutions is found. It consists of two classes. The first one contains the solutions with constant two-dimensional curvature scalar of our specific metrics, and the representatives are the famous Robertson-Walker metrics. One of them we called the "gravitational bubbles", which is compact and with zero Weyl tensor. The second class is more general, with varying curvature scalar. We found its representative as the one-parameter family. It appears that it can be conformally covered by the thee-parameter Mannheim-Kazanas solution. We also investigated the general structure of the energy-momentum tensor in the spherical conformal gravity and constructed the vectorial equation that reveals clearly the same features of non-vacuum solu...
Characterizing student mathematics teachers' levels of understanding in spherical geometry
Guven, Bulent; Baki, Adnan
2010-12-01
This article presents an exploratory study aimed at the identification of students' levels of understanding in spherical geometry as van Hiele did for Euclidean geometry. To do this, we developed and implemented a spherical geometry course for student mathematics teachers. Six structured, task-based interviews were held with eight student mathematics teachers at particular times through the course to determine the spherical geometry learning levels. After identifying the properties of spherical geometry levels, we developed Understandings in Spherical Geometry Test to test whether or not the levels form hierarchy, and 58 student mathematics teachers took the test. The outcomes seemed to support our theoretical perspective that there are some understanding levels in spherical geometry that progress through a hierarchical order as van Hiele levels in Euclidean geometry.
Energetic particles in spherical tokamak plasmas
McClements, K. G.; Fredrickson, E. D.
2017-05-01
Spherical tokamaks (STs) typically have lower magnetic fields than conventional tokamaks, but similar mass densities. Suprathermal ions with relatively modest energies, in particular beam-injected ions, consequently have speeds close to or exceeding the Alfvén velocity, and can therefore excite a range of Alfvénic instabilities which could be driven by (and affect the behaviour of) fusion α-particles in a burning plasma. STs heated with neutral beams, including the small tight aspect ratio tokamak (START), the mega amp spherical tokamak (MAST), the national spherical torus experiment (NSTX) and Globus-M, have thus provided an opportunity to study toroidal Alfvén eigenmodes (TAEs), together with higher frequency global Alfvén eigenmodes (GAEs) and compressional Alfvén eigenmodes (CAEs), which could affect beam current drive and channel fast ion energy into bulk ions in future devices. In NSTX GAEs were correlated with a degradation of core electron energy confinement. In MAST pulses with reduced magnetic field, CAEs were excited across a wide range of frequencies, extending to the ion cyclotron range, but were suppressed when hydrogen was introduced to the deuterium plasma, apparently due to mode conversion at ion-ion hybrid resonances. At lower frequencies fishbone instabilities caused fast particle redistribution in some MAST and NSTX pulses, but this could be avoided by moving the neutral beam line away from the magnetic axis or by operating the plasma at either high density or elevated safety factor. Fast ion redistribution has been observed during GAE avalanches on NSTX, while in both NSTX and MAST fast ions were transported by saturated kink modes, sawtooth crashes, resonant magnetic perturbations and TAEs. The energy dependence of fast ion redistribution due to both sawteeth and TAEs has been studied in Globus-M. High energy charged fusion products are unconfined in present-day STs, but have been shown in MAST to provide a useful diagnostic of beam ion
Spherical solitons in Earth’S mesosphere plasma
Energy Technology Data Exchange (ETDEWEB)
Annou, K., E-mail: kannou@cdta.dz [Centre de développement des technologies avancées (Algeria); Annou, R. [USTHB, Faculty of physics (Algeria)
2016-01-15
Soliton formation in Earth’s mesosphere plasma is described. Nonlinear acoustic waves in plasmas with two-temperature ions and a variable dust charge where transverse perturbation is dealt with are studied in bounded spherical geometry. Using the perturbation method, a spherical Kadomtsev–Petviashvili equation that describes dust acoustic waves is derived. It is found that the parameters taken into account have significant effects on the properties of nonlinear waves in spherical geometry.
Maximum mass of a barotropic spherical star
Fujisawa, Atsuhito; Yoo, Chul-Moon; Nambu, Yasusada
2015-01-01
The ratio of total mass $M$ to surface radius $R$ of spherical perfect fluid ball has an upper bound, $M/R < B$. Buchdahl obtained $B = 4/9$ under the assumptions; non-increasing mass density in outward direction, and barotropic equation of states. Barraco and Hamity decreased the Buchdahl's bound to a lower value $B = 3/8$ $(< 4/9)$ by adding the dominant energy condition to Buchdahl's assumptions. In this paper, we further decrease the Barraco-Hamity's bound to $B \\simeq 0.3636403$ $(< 3/8)$ by adding the subluminal (slower-than-light) condition of sound speed. In our analysis, we solve numerically Tolman-Oppenheimer-Volkoff equations, and the mass-to-radius ratio is maximized by variation of mass, radius and pressure inside the fluid ball as functions of mass density.
Angular momentum in cluster Spherical Collapse Model
Cupani, Guido; Mardirossian, Fabio
2011-01-01
Our new formulation of the Spherical Collapse Model (SCM-L) takes into account the presence of angular momentum associated with the motion of galaxy groups infalling towards the centre of galaxy clusters. The angular momentum is responsible for an additional term in the dynamical equation which is useful to describe the evolution of the clusters in the non-equilibrium region which is investigated in the present paper. Our SCM-L can be used to predict the profiles of several strategic dynamical quantities as the radial and tangential velocities of member galaxies, and the total cluster mass. A good understanding of the non-equilibrium region is important since it is the natural scenario where to study the infall in galaxy clusters and the accretion phenomena present in these objects. Our results corroborate previous estimates and are in very good agreement with the analysis of recent observations and of simulated clusters.
Electronically Steerable Spherical Array capabilities and interfaces
Taylor, T. H., Jr.
1982-01-01
The development of the Electronically Steerable Spherical Array (ESSA) was started in 1975. ESSA provides the inertialess antenna needed by user satellites for communication over their large coverage angles towards the Tracking Data Relay Satellite System (TDRSS). The performance of ESSA over large coverage angles is better than the performance provided by phased arrays. The primary difference between the two antenna types is the method of beam forming. The ESSA steers a beam by illuminating a set of elements which point in the desired direction. This set of elements is illuminated by a simple multipole switch called a switching power divider (SPD). Attention is given to details regarding the difference in performance between ESSA and phased arrays, the ESSA block diagram, the performance improvement achieved by phase compensation, power requirements, the four operating modes, multibeam operation, and the data interface.
On three-dimensional spherical acoustic cloaking
Energy Technology Data Exchange (ETDEWEB)
Munteanu, Ligia; Chiroiu, Veturia, E-mail: ligia_munteanu@hotmail.com, E-mail: veturiachiroiu@yahoo.com [Institute of Solid Mechanics, Romanian Academy, 15 Constantin Mille, PO Box 1-863, 010141 Bucharest (Romania)
2011-08-15
Transformation acoustics opens a new avenue towards the design of acoustic metamaterials, which are materials engineered at the subwavelength scale in order to mimic the parameters in wave equations. The design of the acoustic cloaking is based on the property of equations being invariant under a coordinate transformation, i.e. a specific spatial compression is equivalent to a variation of the material parameters in the original space. In this paper, the sound invisibility performance is discussed for spherical cloaks. The original domain consists of alternating concentric layers made from piezoelectric ceramics and epoxy resin, following a triadic Cantor sequence. The spatial compression, obtained by applying the concave-down transformation, leads to an equivalent domain with an inhomogeneous and anisotropic distribution of the material parameters.
Spherical Boson Stars as Black Hole mimickers
Guzman, F S; 10.1103/PhysRevD.80.084023
2010-01-01
We present spherically symmetric boson stars as black hole mimickers based on the power spectrum of a simple accretion disk model. The free parameters of the boson star are the mass of the boson and the fourth order self-interaction coefficient in the scalar field potential. We show that even if the mass of the boson is the only free parameter it is possible to find a configuration that mimics the power spectrum of the disk due to a black hole of the same mass. We also show that for each value of the self-interaction a single boson star configuration can mimic a black hole at very different astrophysical scales in terms of the mass of the object and the accretion rate. In order to show that it is possible to distinguish one of our mimickers from a black hole we also study the deflection of light.
Corrosion Experiments Using Spherical Uranium Powders
Energy Technology Data Exchange (ETDEWEB)
Powell, G. L. [Y-12 National Security Complex, Oak Ridge, TN (United States); Siekhaus, W. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Teslich, N. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2017-02-01
Corrosion experiments using spherical U powders are continuing with scanning electron microscopy (SEM) showing that the particles are highly textured, 5 m to 25 m diameters with 4% larger particles that are fused smaller particles. This U has a high specific surface area with no corners or back-sides, is well annealed with no machining work, and coated with a coherent oxide film, 30 nm to 300 nm thick. Exposure of this powder to low vapor pressure H_{2}O in the absence of O_{2}, i.e., a vacuum desiccator, resulted in a coherent oxide film growth of ~1 m/y, ~ 10X the growth rate in ambient air, displaying fracture along the growth plane at ~300 nm.
Aharonov-Bohm effect in spherical billiard
Institute of Scientific and Technical Information of China (English)
Dehua Wang
2007-01-01
Using Gutzwiller's periodic orbit theory, we study the quantum level density of a spherical billiard in the presence of a magnetic flux line added at its center, especially discuss the influence of the magnetic flux strength on the quantum level density. The Fourier transformed quantum level density of this system has allowed direct comparison between peaks in the level density and the length of the periodic orbits. For particular magnetic flux strength, the amplitude of the peaks in the level density decreased and some of the peaks disappeared. This result suggests that Aharonov-Bohm effect manifests itself through the cancellation of periodic orbits. This phenomenon will provide a new experimental testing ground for exploring Aharonov-Bohm effect.
Libpsht - algorithms for efficient spherical harmonic transforms
Reinecke, Martin
2010-01-01
Libpsht (or "library for Performant Spherical Harmonic Transforms") is a collection of algorithms for efficient conversion between spatial-domain and spectral-domain representations of data defined on the sphere. The package supports transforms of scalars as well as spin-1 and spin-2 quantities, and can be used for a wide range of pixelisations (including HEALPix, GLESP and ECP). It will take advantage of hardware features like multiple processor cores and floating-point vector operations, if available. Even without this additional acceleration, the employed algorithms are among the most efficient (in terms of CPU time as well as memory consumption) currently being used in the astronomical community. The library is written in strictly standard-conforming C90, ensuring portability to many different hard- and software platforms, and allowing straightforward integration with codes written in various programming languages like C, C++, Fortran, Python etc. Libpsht is distributed under the terms of the GNU General ...
Aerodynamic properties of spherical balloon wind sensors.
Fichtl, G. H.; Demandel, R. E.; Krivo, S. J.
1972-01-01
A first-order theory of the fluctuating lift and drag coefficients associated with the aerodynamically induced motions of rising and falling spherical wind sensors is developed. The equations of motion of a sensor are perturbed about an equilibrium state in which the buoyancy force balances the mean vertical drag force. It is shown that, to within first order in perturbation quantities, the aerodynamic lift force is confined to the horizontal, and the fluctuating drag force associated with fluctuations in the drag coefficient acts along the vertical. The perturbation equations are transformed with Fourier-Stieltjes integrals. The resulting equations lead to relationships between the power spectra of the aerodynamically induced velocity components and the spectra of the fluctuating lift and drag coefficients.
Spherical Accretion in Nearby Weakly Active Galaxies
Moscibrodzka, M A
2005-01-01
We consider the sample of weakly active galaxies situated in 'Local Universe' collected in the paper of Pellegrini (2005) with inferred accretion efficiencies from $10^{-2}$ to $10^{-7}$. We apply a model of spherically symmetrical Bondi accretion for given parameters ($M_{BH}$,$T_{\\infty}$,$\\rho_{\\infty}$,) taken from observation. We calculate spectra emitted by the gas accreting onto its central objects using Monte Carlo method including synchrotron and bremsstrahlung photons as seed photons. We compare our results with observed nuclear X-ray luminosities $L_{X,nuc}$ (0.3-10 keV) of the sample. Model is also tested for different external medium parameters ($\\rho_{\\infty}$ and $T_{\\infty}$) and different free parameters of the model. Our model is able to explain most of the observed nuclear luminosities $L_X$ under an assumption that half of the compresion energy is transfered directly to the electrons.
Free hyperboloidal evolution in spherical symmetry
Vañó-Viñuales, Alex
2016-01-01
We address the hyperboloidal initial value problem in the context of Numerical Relativity, motivated by its evolution on hyperboloidal slices: smooth spacelike slices that reach future null infinity, the "location" in spacetime where radiation is to be extracted. Our approach uses the BSSN and Z4 formulations and a time-independent conformal factor. The resulting system of PDEs includes formally diverging terms at null infinity. Here we discuss a regularized numerical scheme in spherical symmetry. A critical ingredient are the gauge conditions, which control the treatment of future null infinity. Stable numerical evolutions have been performed with regular and black hole initial data on a hyperboloidal slice. A sufficiently large scalar field perturbation will create a black hole, whose final stationary state is different from the trumpet initial data derived here.
Geometric inequalities in spherically symmetric spacetimes
Csukás, Károly Zoltán
2016-01-01
ADM mass is usually preferred against using quasi-local notions of mass in deriving geometric inequalities. We are interested in testing if usage of quasi-local mass provide any benefits. In spherical symmetry there is a highly accepted notion: the Misner-Sharp mass. It is closely related to the energy contained within a 2-surface and its null-expansions, which are used to determine if a surface is trapped. We use it to investigate inequalities between black hole's, Cauchy surface's and normal body's measurable parameters. There are investigations involving quasi-local charge and area. Our aim is to involv quasi-local mass too. This method support wide range of known inequalities and provide some new ones involving mass.
Equivalence Bimodule between Spherical Noncommutative Tori
Institute of Scientific and Technical Information of China (English)
Chun Gil PARK
2003-01-01
Let ni,mj ＞ 1. In [5], the spherical noncommutative torus Sppd was defined by twisting Tr+2 × Zl in Tpd C*(Zl) by a totally skew multiplier p on Tr+2 × Zl for Tpd a pd-homogeneous C*-algebra over Пs4i＝1 S2n+I ×Пs2 S2 ×Пs3j＝1 S2mj-1 ×Пs1 S1 × Tr+2. It is shown that Sppd is strongly Morita equivalent to C(Пs4i＝1 S2ni ×Пs2S2×Пs3j＝1 S2mj-1 ×Пs1 S1) C*(Tr+3× Zl, p).
Theoretical Study of a Spherical Plasma Focus
Ay, Yasar
A theoretical model is developed for two concentric electrodes spherical plasma focus device in order to investigate the plasma sheath dynamics, radiative emission, and the ion properties. The work focuses on the model development of the plasma sheath dynamics and its validation, followed by studying of the radiation effects and the beam-ion properties in such unique geometry as a pulsed source for neutrons, soft and hard x-rays, and electron and ion beams. Chapter 1 is an introduction on fusion systems including plasma focus. Chapter 2 is an extensive literature survey on plasma focus modeling and experiments including the various radiations and their mechanism. Chapter 3 details modeling and validation of the plasma sheath dynamics model with comparison between hydrogen, deuterium, tritium and deuterium-tritium mixture for the production of pulsed neutrons. Chapter 4 is a study of the radiative phase, in which neutron yield is investigated, as well as the predicted beam-ion properties. Chapter 5 summarizes and discusses the results. Chapter 6 provides concluding remarks and proposed future works. The phases of the developed model are the rundown phase I, rundown phase II, the reflected phase and a radiative phase. The rundown phase I starts immediately after the completion of the gas breakdown and ends when the current sheath reaches the equator point of the spherical shape. Then immediately followed by rundown phase II to start and it ends when the shock front hits the axis, which is the beginning of the reflected shock phase. Reflected shock front moves towards the incoming current sheath and meets it which is both the end of the reflected shock phase and the beginning of the radiative phase. After the reflected shock front and the current sheath meet, the current sheath continues to move radially inward by compressing the produced plasma column until it reaches the axis. Since the discharge current contains important information about the plasma dynamic
A note on reflection of spherical waves
Taraldsen, Gunnar
2005-06-01
In 1909 Sommerfeld gave an exact solution for the reflection of a spherical wave from a plane surface in terms of an oscillatory integral and also presented an asymptotic solution for the case where both source and receiver are at the boundary. Weyl (1919) presented an alternative solution and also an asymptotic solution for the case where the source is at the boundary. It is known that the general case is solved if a general solution for the case where the source is at the boundary is known. Here it is demonstrated that it is sufficient to have the general solution for the case where both source and receiver are at the boundary. This is mainly of theoretical interest, but may have practical applications. As an example it is demonstrated that Sommerfeld's approximate solution gives Ingard's (1951) approximate solution which is valid for arbitrary source and receiver heights. .
Advances in spherical neutron polarimetry with Cryopad
Energy Technology Data Exchange (ETDEWEB)
Lelievre-Berna, E. [Institut Laue-Langevin, 6, rue J. Horowitz, BP 156, 38042 Grenoble cedex 9 (France)]. E-mail: lelievre@ill.fr; Bourgeat-Lami, E. [Institut Laue-Langevin, 6, rue J. Horowitz, BP 156, 38042 Grenoble cedex 9 (France); Fouilloux, P. [CEA-DRFMC/SPSMS/MDN, 38054 Grenoble Cedex 9 (France); Geffray, B. [CEA-DRFMC/SPSMS/MDN, 38054 Grenoble Cedex 9 (France); Gibert, Y. [Institut Laue-Langevin, 6, rue J. Horowitz, BP 156, 38042 Grenoble cedex 9 (France); Kakurai, K. [ASRC, JAERI, Tokai, Ibaraki 319-1195 (Japan); Kernavanois, N. [Institut Laue-Langevin, 6, rue J. Horowitz, BP 156, 38042 Grenoble cedex 9 (France); Longuet, B. [CEA-DRFMC/SPSMS/MDN, 38054 Grenoble Cedex 9 (France); Mantegezza, F. [CEA-DRFMC/SPSMS/MDN, 38054 Grenoble Cedex 9 (France); Nakamura, M. [ASRC, JAERI, Tokai, Ibaraki 319-1195 (Japan); Pujol, S. [Institut Laue-Langevin, 6, rue J. Horowitz, BP 156, 38042 Grenoble cedex 9 (France); Regnault, L.-P. [CEA-DRFMC/SPSMS/MDN, 38054 Grenoble Cedex 9 (France); Tasset, F. [Institut Laue-Langevin, 6, rue J. Horowitz, BP 156, 38042 Grenoble cedex 9 (France); Takeda, M. [ASRC, JAERI, Tokai, Ibaraki 319-1195 (Japan); Thomas, M. [Institut Laue-Langevin, 6, rue J. Horowitz, BP 156, 38042 Grenoble cedex 9 (France); Tonon, X. [Institut Laue-Langevin, 6, rue J. Horowitz, BP 156, 38042 Grenoble cedex 9 (France)
2005-02-15
Within the frame of the ILL millennium programme, the European ENPI network and the ILL-ASRC/JAERI Memorandum of Understanding, a third-generation Cryopad has been developed and built in three copies. The aim of this collaboration is to open new fields of investigation on the D3/ILL diffractometer, the IN22/CEA and TAS-1/JAERI three-axis spectrometers: complex antiferromagnetic structures, precision determination of antiferromagnetic distributions, magnetic-lattice excitations spectra, search for the neutron electric dipole moment, etc. We present the progress performed with the new-generation devices and show how easy and reliable it is today to carry out spherical neutron polarimetry measurements with Cryopad.
Mixed convection from an isolated spherical particle
DEFF Research Database (Denmark)
Bhattacharyya, S.; Singh, Ashok
2008-01-01
A numerical study on mixed convection around a hot spherical particle moving vertically downwards in a still fluid medium has been made. The flow field is considered to be axisymmetric for the range of Reynolds number (based on the diameter and the settling velocity of the particle) considered....... A third-order accurate upwind scheme is employed to compute the flow field and the temperature distribution. The form of the wake and the thermal field is analyzed for several values of Grashof number and the Reynolds number. The influence of buoyancy on drag and the rate of heat transfer are studied....... At moderate Reynolds number, recirculating eddy develops in the downstream of the sphere. With the rise of surface temperature this eddy collapses and the fluid adjacent to the heated surface develops into a buoyant plume above the sphere. The increase in surface temperature of the sphere delays the flow...
Dynamical friction force exerted on spherical bodies
Esquivel, O
2007-01-01
We present a rigorous calculation of the dynamical friction force exerted on a spherical massive perturber moving through an infinite homogenous system of field stars. By calculating the shape and mass of the polarization cloud induced by the perturber in the background system, which decelerates the motion of the perturber, we recover Chandrasekhar's drag force law with a modified Coulomb logarithm. As concrete examples we calculate the drag force exerted on a Plummer sphere or a sphere with the density distribution of a Hernquist profile. It is shown that the shape of the perturber affects only the exact form of the Coulomb logarithm. The latter converges on small scales, because encounters of the test and field stars with impact parameters less than the size of the massive perturber become inefficient. We confirm this way earlier results based on the impulse approximation of small angle scatterings.
Spherical collapse for unified dark matter models
Caramês, Thiago R P; Velten, Hermano E S
2014-01-01
We study the non-linear spherical "top hat" collapse for Chaplygin and viscous unified cosmologies. The term unified refers to models where dark energy and dark matter are replaced by one single component. For the generalized Chaplygin gas (GCG) we extend previous results of [R. A. A. Fernandes {\\it et al}. Physical Review D 85, 083501 (2012)]. We discuss the differences at non-linear level between the GCG with $\\alpha=0$ and the $\\Lambda$CDM model. We show that both are indeed different. The bulk viscous model which differs from the GCG due to the existence of non-adiabatic perturbations is also studied. In this case, the clustering process is in general suppressed and the viable parameter space of the viscous model that accelerates the background expansion does not lead to collapsed structures. This result challenges the viability of unified viscous models.
Thermodynamic motivations of spherically symmetric static metrics
Moradpour, H
2015-01-01
Bearing the thermodynamic arguments together with the two definitions of mass in mind, we try to find metrics with spherical symmetry. We consider the adiabatic condition along with the Gong-Wang mass, and evaluate the $g_{rr}$ element which points to a null hypersurface. In addition, we generalize the thermodynamics laws to this hypersurface to find its temperature and thus the corresponding surface gravity which enables us to get a relation for the $g_{tt}$ element. Finally, we investigate the mathematical and physical properties of the discovered metric in the Einstein relativity framework which shows that the primary mentioned null hypersurface is an event horizon. We also show that if one considers the Misner-Sharp mass in the calculations, the Schwarzschild metric will be got. The relationship between the two mass definitions in each metric is studied. The results of considering the geometrical surface gravity are also addressed.
Nonlinear axisymmetric liquid currents in spherical annuli
Astafyeva, N. M.; Vvedenskaya, N. D.; Yavorskaya, I. M.
1978-01-01
A numerical analysis of non-linear axisymmetric viscous flows in spherical annuli of different gap sizes is presented. Only inner sphere was supposed to rotate at a constant angular velocity. The streamlines, lines of constant angular velocity, kinetic energy spectra, and spectra of velocity components are obtained. A total kinetic energy and torque needed to rotate the inner sphere are calculated as functions of Re for different gap sizes. In small-gap annulus nonuniqueness of steady solutions of Navier-Stokes equations is established and regions of different flow regime existences are found. Numerical solutions in a wide-gap annulus and experimental results are used in conclusions about flow stability in the considered range of Re. The comparison of experimental and numerical results shows close qualitative and quantitative agreement.
Stability of Spherical Vesicles in Electric Fields
2010-01-01
The stability of spherical vesicles in alternating (ac) electric fields is studied theoretically for asymmetric conductivity conditions across their membranes. The vesicle deformation is obtained from a balance between the curvature elastic energies and the work done by the Maxwell stresses. The present theory describes and clarifies the mechanisms for the four types of morphological transitions observed experimentally on vesicles exposed to ac fields in the frequency range from 500 to 2 × 107 Hz. The displacement currents across the membranes redirect the electric fields toward the membrane normal to accumulate electric charges by the Maxwell−Wagner mechanism. These accumulated electric charges provide the underlying molecular mechanism for the morphological transitions of vesicles as observed on the micrometer scale. PMID:20575588
Laser Pulse Heating of Spherical Metal Particles
Tribelsky, Michael I.; Miroshnichenko, Andrey E.; Kivshar, Yuri S.; Luk'Yanchuk, Boris S.; Khokhlov, Alexei R.
2011-10-01
We consider the general problem of laser pulse heating of spherical metal particles with the sizes ranging from nanometers to millimeters. We employ the exact Mie solution of the diffraction problem and solve the heat-transfer equation to determine the maximum temperature rise at the particle surface as a function of optical and thermometric parameters of the problem. Primary attention is paid to the case when the thermal diffusivity of the particle is much larger than that of the environment, as it is in the case of metal particles in fluids. We show that, in this case, for any given duration of the laser pulse, the maximum temperature rise as a function of the particle size reaches a maximum at a certain finite size of the particle. We suggest simple approximate analytical expressions for this dependence, which cover the entire parameter range of the problem and agree well with direct numerical simulations.
Saltation movement of large spherical particles
Chara, Z.; Dolansky, J.; Kysela, B.
2017-07-01
The paper presents experimental and numerical investigations of the saltation motion of a large spherical particle in an open channel. The channel bottom was roughed by one layer of glass rods of diameter 6 mm. The plastic spheres of diameter 25.7 mm and density 1160 kgm-3 were fed into the water channel and theirs positions were viewed by a digital camera. Two light sheets were placed above and under the channel, so the flow was simultaneously lighted from the top and the bottom. Only particles centers of which moved through the light sheets were recorded. Using a 2D PIV method the trajectories of the spheres and the velocity maps of the channel flow were analyzed. The Lattice-Boldzmann Method (LBM) was used to simulate the particle motion.
Parametric resonance in spherical immersed elastic shells
Ko, William
2014-01-01
We perform a stability analysis for a fluid-structure interaction problem in which a spherical elastic shell or membrane is immersed in a 3D viscous, incompressible fluid. The shell is an idealised structure having zero thickness, and has the same fluid lying both inside and outside. The problem is formulated mathematically using the immersed boundary framework in which Dirac delta functions are employed to capture the two-way interaction between fluid and immersed structure. The elastic structure is driven parametrically via a time-periodic modulation of the elastic membrane stiffness. We perform a Floquet stability analysis, considering the case of both a viscous and inviscid fluid, and demonstrate that the forced fluid-membrane system gives rise to parametric resonances in which the solution becomes unbounded even in the presence of viscosity. The analytical results are validated using numerical simulations with a 3D immersed boundary code for a range of wavenumbers and physical parameter values. Finally, ...
Dynamic stiffness model of spherical parallel robots
Cammarata, Alessandro; Caliò, Ivo; D`Urso, Domenico; Greco, Annalisa; Lacagnina, Michele; Fichera, Gabriele
2016-12-01
A novel approach to study the elastodynamics of Spherical Parallel Robots is described through an exact dynamic model. Timoshenko arches are used to simulate flexible curved links while the base and mobile platforms are modelled as rigid bodies. Spatial joints are inherently included into the model without Lagrangian multipliers. At first, the equivalent dynamic stiffness matrix of each leg, made up of curved links joined by spatial joints, is derived; then these matrices are assembled to obtain the Global Dynamic Stiffness Matrix of the robot at a given pose. Actuator stiffness is also included into the model to verify its influence on vibrations and modes. The latter are found by applying the Wittrick-Williams algorithm. Finally, numerical simulations and direct comparison to commercial FE results are used to validate the proposed model.
Collective excitations of spherical semiconductor nanoparticles
Moradi, Afshin
2016-10-01
In this article, we study the dispersion properties of bulk and surface electrostatic oscillations of a spherical quantum electron-hole semiconductor plasma as a simple model of a semiconductor nanoparticle. We derive general dispersion relation for both bulk and surface modes, using quantum hydrodynamic theory (including the electrons and holes quantum recoil effects, quantum statistical pressures of the plasma species, as well as exchange and correlation effects) in conjunction with Poisson’s equation and appropriate boundary conditions. We show that for the arbitrary value of angular quantum number {\\ell }≥slant 1 there are only two surface plasmon modes, but two infinite series of bulk modes for {\\ell }≥slant 0 that owe their existence to the curvature of the interface. We use the typical values of GaAs semiconductor to compute the bulk and surface mode frequencies for different value of {\\ell }.
Spherical explosion with central energy source
Masuyama, Miyu; Tsuboki, Yoichiro
2015-01-01
We present a novel semi-analytic solution describing the propagation of a spherical blast wave driven by a central energy source. The initial density profile has a power-law function of the distance from the center and the energy is injected only into the central region at a rate given by a power-law function of time. This solution is composed of three regions separated by the contact surface and the shock front. The innermost region is assumed to be uniform and the outside of the contact surface includes the shocked matter described by self-similar solutions. We analytically derive the applicable range of parameters of this solution from requirements to satisfy boundary conditions. We perform numerical simulations for flows with various values of parameters, some of which reside out of the thus derived applicable range, and compare with the semi-analytic solutions.
Exact Spherically Symmetric Solutions in Massive Gravity
Berezhiani, Z; Nesti, F; Pilo, L
2008-01-01
A phase of massive gravity free from pathologies can be obtained by coupling the metric to an additional spin-two field. We study the gravitational field produced by a static spherically symmetric body, by finding the exact solution that generalizes the Schwarzschild metric to the case of massive gravity. Besides the usual 1/r term, the main effects of the new spin-two field are a shift of the total mass of the body and the presence of a new power-like term, with sizes determined by the mass and the shape (the radius) of the source. These modifications, being source dependent, give rise to a dynamical violation of the Strong Equivalence Principle. Depending on the details of the coupling of the new field, the power-like term may dominate at large distances or even in the ultraviolet. The effect persists also when the dynamics of the extra field is decoupled.
Cusps of Bishop Spherical Indicatrixes and Their Visualizations
Haiming Liu; Donghe Pei
2013-01-01
The main result of this paper is using Bishop Frame and “Type-2 Bishop Frame” to study the cusps of Bishop spherical images and type-2 Bishop spherical images which are deeply related to a space curve and to make them visualized by computer. We find that the singular points of the Bishop spherical images and type-2 Bishop spherical images correspond to the point where Bishop curvatures and type-2 Bishop curvatures vanished and their derivatives are not equal to zero. As applications and illus...
Foliation dependence of black hole apparent horizons in spherical symmetry
Faraoni, Valerio; Firouzjaee, Javad T; Helou, Alexis; Musco, Ilia
2016-01-01
Numerical studies of gravitational collapse to black holes make use of apparent horizons, which are intrinsically foliation-dependent. We expose the problem and discuss possible solutions using the Hawking quasilocal mass. In spherical symmetry, we present a physically sensible approach to the problem by restricting to spherically symmetric spacetime slicings. In spherical symmetry the apparent horizons are gauge-independent in any spherically symmetric foliation but physical quantities associated with them, such as surface gravity and temperature, are not. The widely used comoving and Kodama foliations, which are of particular interest, are discussed in detail.
Foliation dependence of black hole apparent horizons in spherical symmetry
Faraoni, Valerio; Ellis, George F. R.; Firouzjaee, Javad T.; Helou, Alexis; Musco, Ilia
2017-01-01
Numerical studies of gravitational collapse to black holes make use of apparent horizons, which are intrinsically foliation dependent. We expose the problem and discuss possible solutions using the Hawking-Hayward quasilocal mass. In spherical symmetry, we present a physically sensible approach to the problem by restricting to spherically symmetric spacetime slicings. In spherical symmetry, the apparent horizons enjoy a restricted gauge independence in any spherically symmetric foliation, but physical quantities associated with them, such as surface gravity and temperature, are fully gauge dependent. The widely used comoving and Kodama foliations, which are of particular interest, are discussed in detail as examples.
Spherical Arrays for Wireless Channel Characterization and Emulation
DEFF Research Database (Denmark)
Franek, Ondrej; Pedersen, Gert Frølund
2014-01-01
Three types of spherical arrays for use in wireless communication research are presented. First, a spherical array of 32 monopoles with beam steering in arbitrary direction and with arbitrary polarization is described. Next, a spherical array with 16 quad-ridged open-flared horns is introduced, o......, offering better wideband performance and easier beam steering. Finally, a multi-probe setup for over-the-air testing of multiple-input multiple-output mobile devices is presented, being essentially a spherical array with inward radiation....
Investigation of spherical and concentric mechanism of compound droplets
Directory of Open Access Journals (Sweden)
Meifang Liu
2016-07-01
Full Text Available Polymer shells with high sphericity and uniform wall thickness are always needed in the inertial confined fusion (ICF experiments. Driven by the need to control the shape of water-in-oil (W1/O compound droplets, the effects of the density matching level, the interfacial tension and the rotation speed of the continuing fluid field on the sphericity and wall thickness uniformity of the resulting polymer shells were investigated and the spherical and concentric mechanisms were also discussed. The centering of W1/O compound droplets, the location and movement of W1/O compound droplets in the external phase (W2 were significantly affected by the density matching level of the key stage and the rotation speed of the continuing fluid field. Therefore, by optimizing the density matching level and rotation speed, the batch yield of polystyrene (PS shells with high sphericity and uniform wall thickness increased. Moreover, the sphericity also increased by raising the oil/water (O/W2 interfacial tension, which drove a droplet to be spherical. The experimental results show that the spherical driving force is from the interfacial tension affected by the two relative phases, while the concentric driving force, as a resultant force, is not only affected by the three phases, but also by the continuing fluid field. The understanding of spherical and concentric mechanism can provide some guidance for preparing polymer shells with high sphericity and uniform wall thickness.
Low-Q Electrically Small Spherical Magnetic Dipole Antennas
DEFF Research Database (Denmark)
Kim, Oleksiy S.
2010-01-01
Three novel electrically small antenna configurations radiating a TE10 spherical mode corresponding to a magnetic dipole are presented and investigated: multiarm spherical helix (MSH) antenna, spherical split ring resonator (S-SRR) antenna, and spherical split ring (SSR) antenna. All three antennas...... are self-resonant, with the input resistance tuned to 50 ohms by an excitation curved dipole/monopole. A prototype of the SSR antenna has been fabricated and measured, yielding results that are consistent with the numerical simulations. Radiation quality factors (Q) of these electrically small antennas (in...
Dynamical systems and spherically symmetric cosmological models
He, Yanjing
2006-06-01
In this thesis we present a study of the timelike self-similar spherically symmetric cosmological models with two scalar fields with exponential potentials. We first define precisely the timelike self-similar spherically symmetric (TSS) spacetimes. We write the TSS metric in a conformally isometric form in a coordinate system adapted to the geometry of the spacetime manifold. In this coordinate system, both the metric functions of the TSS spacetimes and the potential functions of the scalar fields can be simplified to four undetermined functions of a single coordinate. As a result, the Einstein field equations reduce to an autonomous system of first-order ODEs and polynomial constraints in terms of these undetermined functions. By introducing new bounded variables as well as a new independent variable and solving the constraints, we are able to apply the theory of dynamical systems to study the properties of the TSS solutions. By finding invariant sets and associated monotonic functions, by applying the LaSalle Invariance Principle and the Monotonicity Principle, by applying the [straight phi] t -connected property of a limit set, and using other theorems, we prove that all of the TSS trajectories are heteroclinic trajectories. In addition, we conduct numerical simulations to confirm and support the qualitative analysis. We obtain all possible types of TSS solutions, by analyzing the qualitative behavior of the original system of ODES from those of the reduced one. We obtain asymptotic expressions for the TSS solutions (e.g., the asymptotic expressions for the metric functions, the source functions and the Ricci scalar). In particular, self-similar flat Friedmann-Robertson-Walker spacetimes are examined in order to obtain insights into the issues related to the null surface in general TSS spacetimes in these coordinates. A discussion of the divergence of the spacetime Ricci scalar and the possible extension of the TSS solutions across the null boundary is presented
Explosive fragmentation of liquids in spherical geometry
Milne, A.; Longbottom, A.; Frost, D. L.; Loiseau, J.; Goroshin, S.; Petel, O.
2016-07-01
Rapid acceleration of a spherical shell of liquid following central detonation of a high explosive causes the liquid to form fine jets that are similar in appearance to the particle jets that are formed during explosive dispersal of a packed layer of solid particles. Of particular interest is determining the dependence of the scale of the jet-like structures on the physical parameters of the system, including the fluid properties (e.g., density, viscosity, and surface tension) and the ratio of the mass of the liquid to that of the explosive. The present paper presents computational results from a multi-material hydrocode describing the dynamics of the explosive dispersal process. The computations are used to track the overall features of the early stages of dispersal of the liquid layer, including the wave dynamics, and motion of the spall and accretion layers. The results are compared with new experimental results of spherical charges surrounded by a variety of different fluids, including water, glycerol, ethanol, and vegetable oil, which together encompass a significant range of fluid properties. The results show that the number of jet structures is not sensitive to the fluid properties, but primarily dependent on the mass ratio. Above a certain mass ratio of liquid fill-to-explosive burster (F / B), the number of jets is approximately constant and consistent with an empirical model based on the maximum thickness of the accretion layer. For small values of F / B, the number of liquid jets is reduced, in contrast with explosive powder dispersal, where small F / B yields a larger number of particle jets. A hypothetical explanation of these features based on the nucleation of cavitation is explored numerically.
Bulanov, Stepan; Maksimchuk, Anatoly; Zhidkov, Alexei
2009-11-01
We report on the analytic and computer simulation study of a relativistic spherical wake wave. Such a wave in the breaking regime, traveling towards the center is able to reflect and focus the incoming radiation and up-shifting its frequency. The reflected and focused electromagnetic pulse can have such high intensity, that it is able to create e^+e^- pairs via Schwinger process.
Thermophoresis of spherical and non-spherical particles: a review of theories and experiments.
Zheng, F
2002-03-29
Thermophoresis is an important mechanism of micro-particle transport due to a temperature gradient in the surrounding medium and has found numerous applications, especially in the field of aerosol technology. Extensive studies, both theoretical and experimental, have been done to understand the nature of this phenomenon. However, it is clear that a lot more of work needs to be done before we can predict thermophoresis accurately for any given gas-particle system as well as particle shape and orientation in any flow regime. This paper reviews the existing theories and data in two major categories, for spherical particles and for non-spherical particles, as well as the various techniques in making thermophoresis measurements. The current state of development for thermophoresis studies is that for spheres the theories and experimental data agree with each other fairly well but for non-spherical particles in the transition regime the theories are yet to be developed and experimental data showing the effect of particle shape are much needed in all Knudsen number range. The best techniques of thermophoretic force measurements involve the use of electrodynamic balances to work on single micro-particles and the use of microgravity to minimize the effect of convection. A combination of the above two has not been attempted and should provide the most accurate data.
Effect of the spherical Earth on a simple pendulum
2003-01-01
We consider the period of a simple pendulum in the gravitational field of the spherical Earth. Effectively, gravity is enhanced compared with the often used flat Earth approximation, such that the period of the pendulum is shortened. We discuss the flat Earth approximation, and show when the corrections due to the spherical Earth may be of interest.
Improvements in the spherical collapse model and dark energy cosmologies
Del Popolo, A.
In the present paper, we study how the effects of deviations from spherical symmetry of a system, produced by angular momentum, and shear stress, influence typical parameters of the spherical collapse model, like the linear density threshold for collapse of the non-relativistic component (δ c) and its virial overdensity (Δ V). The study is performed in the framework of the Einstein-de Sitter and Λ CDM models, and assuming that the vacuum component is not clustering within the homogeneous non-spherical overdensities. We start from the standard spherical top hat model (SCM) which does not take account the non-spherical effects, and we add to this model the shear term and angular momentum term, which are finally expressed in terms of the density contrast, δ . We find that the non-spherical terms change the non-linear evolution of the system and that the collapse stops ``naturally" at the virial radius, differently from the standard spherical collapse model. Moreover, shear and rotation gives rise to higher values of the linear overdensity parameter and different values of Δ V with respect to the standard spherical collapse model.
Development of a spherical aerial vehicle for urban search
Hou, Kang; Sun, Hanxu; Jia, Qingxuan; Zhang, Yanheng
2014-06-01
With the ability to provide close surveillance in narrow space or urban areas, spherical aerial vehicles have been of great interest to many scholars and researchers. The spherical aerial vehicle offers substantial design advantages over the conventional small aerial vehicles. As a kind of small aerial vehicles, spherical aerial vehicle is presented in this paper. Firstly, the unique structure of spherical aerial vehicle is presented in detail. And then as the key component of the spherical aerial vehicle, the meshed spherical shell is analyzed. The shell is made of carbon fiber and is used to protect the inner devices, so the deformation of the shell is analyzed and simulated. Then the experimental results verify the above analysis and the composite carbon fiber material makes the mesh spherical shell small deformation. Considering the whole vehicle has a shell outside, the lift affect of the meshed spherical shell is analyzed. The simulation and experiment results are basically consistent with theoretical analysis, and the impact of the meshed shell has small resistance for the airflow through the sphere.
Plasma production by means of discharge in a spherical cavity
Antsiferov, P. S.; Dorokhin, L. A.; Koshelev, K. N.
2010-01-01
The work is devoted to the study of plasma, appearing as a result of cumulation of shock wave with form close to spherical. The shock wave was obtained by triggering of fast discharge (dI/dt about 10(12) A/s) on inner surface of cavity, made from insulator. Spherical cavity with radius 4.5 mm was fi
Negative Trions Trapped by a Spherical Parabolic Quantum Dot
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
In this paper, a negatively charged exciton trapped by a spherical parabolic quantum dot has been investigated. The energy spectra of low-lying states are calculated by means of matrix diagonalization. The important feature of the low-lying states of the negatively charged excitons in a spherical quantum dot is obtained via an analysis of the energy spectra.
Systematic Calibration for a Backpacked Spherical Photogrammetry Imaging System
Rau, J. Y.; Su, B. W.; Hsiao, K. W.; Jhan, J. P.
2016-06-01
A spherical camera can observe the environment for almost 720 degrees' field of view in one shoot, which is useful for augmented reality, environment documentation, or mobile mapping applications. This paper aims to develop a spherical photogrammetry imaging system for the purpose of 3D measurement through a backpacked mobile mapping system (MMS). The used equipment contains a Ladybug-5 spherical camera, a tactical grade positioning and orientation system (POS), i.e. SPAN-CPT, and an odometer, etc. This research aims to directly apply photogrammetric space intersection technique for 3D mapping from a spherical image stereo-pair. For this purpose, several systematic calibration procedures are required, including lens distortion calibration, relative orientation calibration, boresight calibration for direct georeferencing, and spherical image calibration. The lens distortion is serious on the ladybug-5 camera's original 6 images. Meanwhile, for spherical image mosaicking from these original 6 images, we propose the use of their relative orientation and correct their lens distortion at the same time. However, the constructed spherical image still contains systematic error, which will reduce the 3D measurement accuracy. Later for direct georeferencing purpose, we need to establish a ground control field for boresight/lever-arm calibration. Then, we can apply the calibrated parameters to obtain the exterior orientation parameters (EOPs) of all spherical images. In the end, the 3D positioning accuracy after space intersection will be evaluated, including EOPs obtained by structure from motion method.
SYSTEMATIC CALIBRATION FOR A BACKPACKED SPHERICAL PHOTOGRAMMETRY IMAGING SYSTEM
Directory of Open Access Journals (Sweden)
J. Y. Rau
2016-06-01
Full Text Available A spherical camera can observe the environment for almost 720 degrees’ field of view in one shoot, which is useful for augmented reality, environment documentation, or mobile mapping applications. This paper aims to develop a spherical photogrammetry imaging system for the purpose of 3D measurement through a backpacked mobile mapping system (MMS. The used equipment contains a Ladybug-5 spherical camera, a tactical grade positioning and orientation system (POS, i.e. SPAN-CPT, and an odometer, etc. This research aims to directly apply photogrammetric space intersection technique for 3D mapping from a spherical image stereo-pair. For this purpose, several systematic calibration procedures are required, including lens distortion calibration, relative orientation calibration, boresight calibration for direct georeferencing, and spherical image calibration. The lens distortion is serious on the ladybug-5 camera’s original 6 images. Meanwhile, for spherical image mosaicking from these original 6 images, we propose the use of their relative orientation and correct their lens distortion at the same time. However, the constructed spherical image still contains systematic error, which will reduce the 3D measurement accuracy. Later for direct georeferencing purpose, we need to establish a ground control field for boresight/lever-arm calibration. Then, we can apply the calibrated parameters to obtain the exterior orientation parameters (EOPs of all spherical images. In the end, the 3D positioning accuracy after space intersection will be evaluated, including EOPs obtained by structure from motion method.
Characterizing Student Mathematics Teachers' Levels of Understanding in Spherical Geometry
Guven, Bulent; Baki, Adnan
2010-01-01
This article presents an exploratory study aimed at the identification of students' levels of understanding in spherical geometry as van Hiele did for Euclidean geometry. To do this, we developed and implemented a spherical geometry course for student mathematics teachers. Six structured, "task-based interviews" were held with eight student…
Decay rates of spherical and deformed proton emitters
Energy Technology Data Exchange (ETDEWEB)
Davids, C. N.; Esbensen, H.
1999-11-23
Using Green's function techniques, the authors derive expressions for the width of a proton decaying state in spherical and deformed nuclei. The authors show that the proton decay widths calculated by the exact expressions of Maglione et al. are equivalent to the distorted wave expressions of Bugrov et al., and that of {angstrom} berg et al. in the spherical case.
Transport coefficients for rigid spherically symmetric polymers or aggregates
Strating, P.; Wiegel, F.W.
1994-01-01
In this paper we investigate the transport properties for rigid spherically symmetric macromolecules, having a segment density distribution falling off as r- lambda . We calculate the rotational and translational diffusion coefficient for a spherically symmetric polymer and the shear viscosity for a
Rapid Prototyping of Electrically Small Spherical Wire Antennas
DEFF Research Database (Denmark)
Kim, Oleksiy S.
2014-01-01
It is shown how modern rapid prototyping technologies can be applied for quick and inexpensive, but still accurate, fabrication of electrically small wire antennas. A well known folded spherical helix antenna and a novel spherical zigzag antenna have been fabricated and tested, exhibiting...
Theory and applications of spherical microphone array processing
Jarrett, Daniel P; Naylor, Patrick A
2017-01-01
This book presents the signal processing algorithms that have been developed to process the signals acquired by a spherical microphone array. Spherical microphone arrays can be used to capture the sound field in three dimensions and have received significant interest from researchers and audio engineers. Algorithms for spherical array processing are different to corresponding algorithms already known in the literature of linear and planar arrays because the spherical geometry can be exploited to great beneficial effect. The authors aim to advance the field of spherical array processing by helping those new to the field to study it efficiently and from a single source, as well as by offering a way for more experienced researchers and engineers to consolidate their understanding, adding either or both of breadth and depth. The level of the presentation corresponds to graduate studies at MSc and PhD level. This book begins with a presentation of some of the essential mathematical and physical theory relevant to ...
Vibrations of moderately thick shallow spherical shells at large amplitudes
Sathyamoorthy, M.
1994-04-01
A shallow shell theory is presented for the geometrically nonlinear analysis of moderately thick isotropic spherical shells. Effects of transverse shear deformation and rotatory inertia are included in the governing equations of motion by means of tracing constants. When these effects are ignored, the governing equations readily reduce to those applicable for thin shallow spherical shells. Solutions to the system of thick shell equations are obtained by means of Galerkin's method and the numerical Runge-Kutta procedure. Numerical results are presented for certain cases of shallow spherical shells considering different geometric shell parameters. Transverse shear and rotatory inertia effects are found to be important in linear as well as nonlinear responses of shallow spherical shells. The nonlinear frequency-amplitude behavior is of the softening type for shallow spherical shells and of the hardening type for circular plates. Frequency ratios are lower at any given amplitude when the effects of transverse shear and rotatory inertia are included in the analysis.
Spherical radial basis functions, theory and applications
Hubbert, Simon; Morton, Tanya M
2015-01-01
This book is the first to be devoted to the theory and applications of spherical (radial) basis functions (SBFs), which is rapidly emerging as one of the most promising techniques for solving problems where approximations are needed on the surface of a sphere. The aim of the book is to provide enough theoretical and practical details for the reader to be able to implement the SBF methods to solve real world problems. The authors stress the close connection between the theory of SBFs and that of the more well-known family of radial basis functions (RBFs), which are well-established tools for solving approximation theory problems on more general domains. The unique solvability of the SBF interpolation method for data fitting problems is established and an in-depth investigation of its accuracy is provided. Two chapters are devoted to partial differential equations (PDEs). One deals with the practical implementation of an SBF-based solution to an elliptic PDE and another which describes an SBF approach for solvi...
Plasmonic and silicon spherical nanoparticle antireflective coatings
Baryshnikova, K. V.; Petrov, M. I.; Babicheva, V. E.; Belov, P. A.
2016-03-01
Over the last decade, plasmonic antireflecting nanostructures have been extensively studied to be utilized in various optical and optoelectronic systems such as lenses, solar cells, photodetectors, and others. The growing interest to all-dielectric photonics as an alternative optical technology along with plasmonics motivates us to compare antireflective properties of plasmonic and all-dielectric nanoparticle coatings based on silver and crystalline silicon respectively. Our simulation results for spherical nanoparticles array on top of amorphous silicon show that both silicon and silver coatings demonstrate strong antireflective properties in the visible spectral range. For the first time, we show that zero reflectance from the structure with silicon coatings originates from the destructive interference of electric- and magnetic-dipole responses of nanoparticle array with the wave reflected from the substrate, and we refer to this reflection suppression as substrate-mediated Kerker effect. We theoretically compare the silicon and silver coating effectiveness for the thin-film photovoltaic applications. Silver nanoparticles can be more efficient, enabling up to 30% increase of the overall absorbance in semiconductor layer. Nevertheless, silicon coatings allow up to 64% absorbance increase in the narrow band spectral range because of the substrate-mediated Kerker effect, and band position can be effectively tuned by varying the nanoparticles sizes.
L curve for spherical triangle region quadtrees
Institute of Scientific and Technical Information of China (English)
YUAN; Wen; CHENG; Chengqi; MA; Ainai; GUAN; Xiaojing
2004-01-01
The sequence of facets and nodes has a direct influence on the efficiency of access to spherical triangle region quadtree. Based on the labeling schema by Lee,spatial curves both for facets and nodes are proposed and the main algorithms for coordinate translation, node L sequence generation and visiting nodes are presented. In particular, constant time algorithms for generating node L sequence are advanced by using bit manipulation operations, which can be easily implemented with hardware. In L curve the distance between three nodes of a facet is mostly limited in a range of small value, thus making fast access possible. Though codes of sibling facets are continuous,the difference between codes of some cousins may occasionally be very large and makes the distance of a few facets also very large, thus greatly increasing the mean node distance and the total traversing distance. Therefore an m cluster of nodes is proposed as a basic storage unit for n cluster, which should store every shared node in each, and the distance between three nodes of a facet is limited to a controllable scope.
Spherical gravitational curvature boundary-value problem
Šprlák, Michal; Novák, Pavel
2016-08-01
Values of scalar, vector and second-order tensor parameters of the Earth's gravitational field have been collected by various sensors in geodesy and geophysics. Such observables have been widely exploited in different parametrization methods for the gravitational field modelling. Moreover, theoretical aspects of these quantities have extensively been studied and well understood. On the other hand, new sensors for observing gravitational curvatures, i.e., components of the third-order gravitational tensor, are currently under development. As the gravitational curvatures represent new types of observables, their exploitation for modelling of the Earth's gravitational field is a subject of this study. Firstly, the gravitational curvature tensor is decomposed into six parts which are expanded in terms of third-order tensor spherical harmonics. Secondly, gravitational curvature boundary-value problems defined for four combinations of the gravitational curvatures are formulated and solved in spectral and spatial domains. Thirdly, properties of the corresponding sub-integral kernels are investigated. The presented mathematical formulations reveal some important properties of the gravitational curvatures and extend the so-called Meissl scheme, i.e., an important theoretical framework that relates various parameters of the Earth's gravitational field.
Azimuthal dynamo wave in spherical shell convection
Cole, Elizabeth; Mantere, Maarit J; Brandenburg, Axel
2013-01-01
We report the finding of an azimuthal dynamo wave of a low-order (m=1) mode in direct numerical simulations (DNS) of turbulent convection in spherical shells. Such waves are predicted by mean field dynamo theory and have been obtained previously in mean-field models. Observational results both from photometry and Doppler imaging have revealed persistent drifts of spots for several rapidly rotating stars, but, although an azimuthal dynamo wave has been proposed as a possible mechanism responsible for this behavior, it has been judged as unlikely, as practical evidence for such waves from DNS has been lacking. The large-scale magnetic field in our DNS, which is due to self-consistent dynamo action, is dominated by a retrograde m=1 mode. Its pattern speed is nearly independent of latitude and does not reflect the speed of the differential rotation at any depth. The extrema of magnetic m=1 structures coincide reasonably with the maxima of m=2 structures of the temperature. These results provide direct support for...
Bounce-free spherical hydrodynamic implosion
Kagan, Grigory; Tang, Xian-Zhu; Hsu, Scott C.; Awe, Thomas J.
2011-10-01
In a bounce-free spherical hydrodynamic implosion, the post-stagnation hot core plasma does not expand against the imploding flow. A solution family realizing such a regime has been explicitly found. This regime found is most naturally applied and would be of most benefit to plasma liner driven magneto-inertial fusion (MIF). That is, this version of inertial confinement relies on maintaining the compressed hot spot within the thermonuclear burning condition for as long as possible, rather than on initiating the burn wave. Consequently, in MIF it is the best-case scenario that the fuel target persists in the state of maximum compression after reaching stagnation. Also, the plasma liner driven MIF provides substantial freedom in shaping the profiles of the imploding flow (i.e. liner) pressure, density and fluid velocity. By comparing the fuel disassembly time against that of a stationary imploding flow case, we find that shaping this flow appropriately is likely to increase the dwell time and fusion gain by a factor of four or more. Moreover, in this newly found regime the shocked region of the liner is at rest. That is, the kinetic energy of the original liner is entirely converted into internal energy. Hence, our result supports the idea of using the deuterium-tritium in the inner parts of the liner or the so-called ``after-burner,'' which upon becoming shocked will also burn, thus further increasing the gain. The work is supported by LANL LDRD.
Scaling regimes in spherical shell rotating convection
Gastine, T; Aubert, J
2016-01-01
Rayleigh-B\\'enard convection in rotating spherical shells can be considered as a simplified analogue of many astrophysical and geophysical fluid flows. Here, we use three-dimensional direct numerical simulations to study this physical process. We construct a dataset of more than 200 numerical models that cover a broad parameter range with Ekman numbers spanning $3\\times 10^{-7} \\leq E \\leq 10^{-1}$, Rayleigh numbers within the range $10^3 < Ra < 2\\times 10^{10}$ and a Prandtl number unity. We investigate the scaling behaviours of both local (length scales, boundary layers) and global (Nusselt and Reynolds numbers) properties across various physical regimes from onset of rotating convection to weakly-rotating convection. Close to critical, the convective flow is dominated by a triple force balance between viscosity, Coriolis force and buoyancy. For larger supercriticalities, a subset of our numerical data approaches the asymptotic diffusivity-free scaling of rotating convection $Nu\\sim Ra^{3/2}E^{2}$ in ...
The Ambivalent Position and its Reason of Platonic Unity of Virtue%柏拉图在美德的统一性问题上的矛盾立场及其缘由
Institute of Scientific and Technical Information of China (English)
黎良华
2014-01-01
美德的统一性问题是希腊哲学所重点讨论的哲学问题。在柏拉图那里，个人的美德具有一种统一性关系，但公民的美德却体现出一种各阶层具有专属于自身的特定美德的倾向。在美德的统一性问题上，柏拉图在个人美德与公民美德之间体现出某种矛盾性立场，其中缘由在于柏拉图在哲学上的二元论立场所带来的实践上的二元关怀。%The unity of virtues is an important Greek philosophical issue. For Plato,individual virtues were unified,but civic virtues tended to represent a specific social class. The ambivalent position of unified individual virtues with non-unified civic virtues in Plato's philosophy was due to platonic dualism.
Bed of polydisperse viscous spherical drops under thermocapillary effects
Sharanya, V.; Raja Sekhar, G. P.; Rohde, Christian
2016-08-01
Viscous flow past an ensemble of polydisperse spherical drops is investigated under thermocapillary effects. We assume that the collection of spherical drops behaves as a porous media and estimates the hydrodynamic interactions analytically via the so- called cell model that is defined around a specific representative particle. In this method, the hydrodynamic interactions are assumed to be accounted by suitable boundary conditions on a fictitious fluid envelope surrounding the representative particle. The force calculated on this representative particle will then be extended to a bed of spherical drops visualized as a Darcy porous bed. Thus, the "effective bed permeability" of such a porous bed will be computed as a function of various parameters and then will be compared with Carman-Kozeny relation. We use cell model approach to a packed bed of spherical drops of uniform size (monodisperse spherical drops) and then extend the work for a packed bed of polydisperse spherical drops, for a specific parameters. Our results show a good agreement with the Carman-Kozeny relation for the case of monodisperse spherical drops. The prediction of overall bed permeability using our present model agrees well with the Carman-Kozeny relation when the packing size distribution is narrow, whereas a small deviation can be noted when the size distribution becomes broader.
Spherical Accretion in a Uniformly Expanding Universe
Colpi, Monica; Shapiro, Stuart L.; Wasserman, Ira
1996-10-01
We consider spherically symmetric accretion of material from an initially homogeneous, uniformly expanding medium onto a Newtonian point mass M. The gas is assumed to evolve adiabatically with a constant adiabatic index F, which we vary over the range Γ ɛ [1, 5/3]. We use a one-dimensional Lagrangian code to follow the spherical infall of material as a function of time. Outflowing shells gravitationally bound to the point mass fall back, giving rise to a inflow rate that, after a rapid rise, declines as a power law in time. If there were no outflow initially, Bondi accretion would result, with a characteristic accretion time-scale ta,0. For gas initially expanding at a uniform rate, with a radial velocity U = R/t0 at radius R, the behavior of the flow at all subsequent times is determined by ta,0/t0. If ta,0/t0 ≫ 1, the gas has no time to respond to pressure forces, so the fluid motion is nearly collisionless. In this case, only loosely bound shells are influenced by pressure gradients and are pushed outward. The late-time evolution of the mass accretion rate Mdot is close to the result for pure dust, and we develop a semianalytic model that accurately accounts for the small effect of pressure gradients in this limit. In the opposite regime, ta,0/t0 ≪ 1, pressure forces significantly affect the motion of the gas. At sufficiently early times, t ≤ ttr, the flow evolved along a sequence of quasi-stationary, Bondi-like states, with a time-dependent Mdot determined by the slowly varying gas density at large distances. However, at later times, t ≥ ttr, the fluid flow enters a dustllke regime; ttr is the time when the instantaneous Bondi accretion radius reaches the marginally bound radius. The transition time ttr depends sensitively on ta,0/t0 for a given Γ and can greatly exceed t0. We show that there exists a critical value Γ = 11/9, below which the transition from fluid to ballistic motion disappears. As one application of our calculations, we consider the
Experimental investigation of reshocked spherical gas interfaces
Si, Ting; Zhai, Zhigang; Yang, Jiming; Luo, Xisheng
2012-05-01
The evolution of a spherical gas interface under reshock conditions is experimentally studied using the high-speed schlieren photography with high time resolutions. A number of experimental sets of helium or SF6 bubble surrounded by air for seven different end wall distances have been performed. Distinct flow structures are observed due to the additional vorticity and wave configuration caused by the reshock. In the air/helium case, the deformation of the reshocked bubble is dependent on the development of the penetrating air jet along the symmetry axis of the bubble. In general, two separate vortex rings can be observed, i.e., one develops slowly, and the other approaches and eventually impinges on the shock tube end wall. In the air/SF6 case, two SF6 jets moving in opposite directions are generated and the oscillation of the interface is observed for small end wall distances, while small scale vortex morphologies on the gas interface are found for large end wall distances. The physical mechanisms of the baroclinic vorticity generation and the pressure perturbation are highlighted in the interface evolution process. Based on the sequence of the schlieren images obtained during a single run for each case, the x-t diagrams of the shock and reshock interacting with the helium or SF6 bubble are plotted and the velocities estimated in linear stages are compared with those calculated from one-dimensional gas dynamics. The changes with time in the characteristic bubble sizes including the interface length, height, and vortex diameter are also measured.
Time reversal for a single spherical scatterer.
Chambers, D H; Gautesen, A K
2001-06-01
We show that the time reversal operator for a planar time reversal mirror (TRM) can have up to four distinct eigenvalues with a small spherical acoustic scatterer. Each eigenstate represents a resonance between the TRM and an induced scattering moment of the sphere. Their amplitude distributions on the TRM are orthogonal superpositions of the radiation patterns from a monopole and up to three orthogonal dipoles. The induced monopole moment is associated with the compressibility contrast between the sphere and the medium, while the dipole moments are associated with density contrast. The number of eigenstates is related to the number of orthogonal orientations of each induced multipole. For hard spheres (glass, metals) the contribution of the monopole moment to the eigenvalues is much greater than that of the dipole moments, leading to a single dominant eigenvalue. The other eigenvalues are much smaller, making it unlikely multiple eigenvalues could have been observed in previous experiments using hard materials. However, for soft materials such as wood, plastic, or air bubbles the eigenvalues are comparable in magnitude and should be observable. The presence of multiple eigenstates breaks the one-to-one correspondence between eigenstates and distinguishable scatterers discussed previously by Prada and Fink [Wave Motion 20, 151-163 (1994)]. However, eigenfunctions from separate scatterers would have different phases for their eigenfunctions, potentially restoring the ability to distinguish separate scatterers. Since relative magnitudes of the eigenvalues for a single scatterer are governed by the ratio of the compressibility contrast to the density contrast, measurement of the eigenvalue spectrum would provide information on the composition of the scatterer.
HFE and Spherical Cryostats MC Study
Energy Technology Data Exchange (ETDEWEB)
Brodsky, Jason P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2016-09-26
The copper vessel containing the nEXO TPC is surrounded by a buffer of HFE, a liquid refrigerant with very low levels of radioactive element contamination. The HFE is contained within the cryostat’s inner vessel, which is in turn inside the outer vessel. While some HFE may be necessary for stable cooling of nEXO, it is possible that using substantially more than necessary for thermal reasons will help reduce backgrounds originating in the cryostats. Using a larger amount of HFE is accomplished by making the cryostat vessels larger. By itself, increasing the cryostat size somewhat increases the background rate, as the thickness of the cryostat wall must increase at larger sizes. However, the additional space inside the cryostat will be filled with HFE which can absorb gamma rays headed for the TPC. As a result, increasing the HFE reduces the number of backgrounds reaching the TPC. The aim of this study was to determine the relationship between HFE thickness and background rate. Ultimately, this work should support choosing a cryostat and HFE size that satisfies nEXO’s background budget. I have attempted to account for every consequence of changing the cryostat size, although naturally this remains a work in progress until a final design is achieved. At the moment, the scope of the study includes only the spherical cryostat design. This study concludes that increasing cryostat size reduces backgrounds, reaching neglible backgrounds originating from the cryostat at the largest sizes. It also shows that backgrounds originating from the inherent radioactivity of the HFE plateau quickly, so may be considered essentially fixed at any quantity of HFE.
Complete classification of spherically symmetric static spacetimes via Noether symmetries
Ali, Farhad; Ali, Sajid
2013-01-01
In this paper we give a complete classification of spherically symmetric static space-times by their Noether symmetries. The determining equations for Noether symmetries are obtained by using the usual Lagrangian of a general spherically symmetric static spacetime which are integrated for each case. In particular we observe that spherically symmetric static spacetimes are categorized into six distinct classes corresponding to Noether algebra of dimensions 5, 6, 7, 9, 11 and 17. Using Noether`s theorem we also write down the first integrals for each class of such spacetimes corresponding to their Noether symmetries.
Virial theorem and hypervirial theorem in a spherical geometry
Energy Technology Data Exchange (ETDEWEB)
Li Yan; Chen Jingling [Theoretical Physics Division, Chern Institute of Mathematics, Nankai University, Tianjin 300071 (China); Zhang Fulin, E-mail: flzhang@tju.edu.cn, E-mail: chenjl@nankai.edu.cn [Physics Department, School of Science, Tianjin University, Tianjin 300072 (China)
2011-09-09
The virial theorem in the one- and two-dimensional spherical geometry are presented in both classical and quantum mechanics. Choosing a special class of hypervirial operators, the quantum hypervirial relations in the spherical spaces are obtained. With the aid of the Hellmann-Feynman theorem, these relations can be used to formulate a perturbation theorem without wavefunctions, corresponding to the hypervirial-Hellmann-Feynman theorem perturbation theorem of Euclidean geometry. The one-dimensional harmonic oscillator and two-dimensional Coulomb system in the spherical spaces are given as two sample examples to illustrate the perturbation method. (paper)
Spherical interferometry for the characterization of precision spheres
Nicolaus, R. A.; Bartl, G.
2016-09-01
Interferometry with spherical wavefronts is usually used for characterizing precise optics. A special spherical interferometer was set up to measure the volume of high precision spheres used for the new definition of the SI unit kilogram, for which a fundamental constant, such as Planck’s constant h or Avogadro’s constant N A, was to be determined. Furthermore with this type of interferometer and with a special evaluating algorithm, absolute form deviations of spheres can be determined. With this knowledge, a sphere can be processed further to reach unrivaled small sphericity deviations.
Electrically small circularly polarized spherical antenna with air core
DEFF Research Database (Denmark)
Kim, O. S.
2013-01-01
An electrically small circularly polarized self-resonant spherical antenna with air core is presented. The antenna is a modified multiarm spherical helix exciting TM10 and TE10 spherical modes with equal radiated power, and thus yielding perfect circular polarization over the entire far......-field sphere (except the polar regions, where the radiation is low). The self-resonance is achieved by exciting higher-order TM modes, which provide the necessary electric stored energy in the near-field, while contributing negligibly to the far-field radiation of the antenna. The antenna has electrical size...
Non-Spherical Microcapsules for Increased Core Content Volume Delivery
Oliva-Buisson, Yvette J.
2014-01-01
The goal of this project was to advance microencapsulation from the standard spherical microcapsule to a non-spherical, high-aspect ratio (HAR), elongated microcapsule. This was to be accomplished by developing reproducible methods of synthesizing or fabricating robust, non-spherical, HAR microcapsules. An additional goal of this project was to develop the techniques to the point where scale-up of these methods could be examined. Additionally, this project investigated ways to apply the microencapsulation techniques developed as part of this project to self-healing formulations.
Analytical solution of the simplified spherical harmonics equations in spherical turbid media
Edjlali, Ehsan; Bérubé-Lauzière, Yves
2016-10-01
We present for the first time an analytical solution for the simplified spherical harmonics equations (so-called SPN equations) in the case of a steady-state isotropic point source inside a spherical homogeneous absorbing and scattering medium. The SPN equations provide a reliable approximation to the radiative transfer equation for describing light transport inside turbid media. The SPN equations consist of a set of coupled partial differential equations and the eigen method is used to obtain a set of decoupled equations, each resembling the heat equation in the Laplace domain. The equations are solved for the realistic partial reflection boundary conditions accounting for the difference in refractive indices between the turbid medium and its environment (air) as occurs in practical cases of interest in biomedical optics. Specifically, we provide the complete solution methodology for the SP3, which is readily applicable to higher orders as well, and also give results for the SP5. This computationally easy to obtain solution is investigated for different optical properties of the turbid medium. For validation, the solution is also compared to the analytical solution of the diffusion equation and to gold standard Monte Carlo simulation results. The SP3 and SP5 analytical solutions prove to be in good agreement with the Monte Carlo results. This work provides an additional tool for validating numerical solutions of the SPN equations for curved geometries.
Guo, Xiaoxia; Zhao, Kongshuang
2017-07-01
We report here a dielectric study on cationic and anionic spherical polyelectrolyte brush (SPB) (consisting of a polystyrene (PS) core and poly (2-aminoethylmethacrylate hydrochloride (PAEMH) chains or poly (acrylic acid) (PAA) chains grafted onto the core) suspensions over a frequency range of 40 Hz-110 MHz. The relaxation behavior of the suspensions shows significant changes in the brush layer properties when changing the particle mass fraction or pH of the system. After eliminating the electrode polarization effect at a low frequency, two definite relaxations related to interfacial polarization, around 100 kHz and 10 MHz respectively, are observed. Based on a single layer spherical-shell model, we developed a curve-fitting procedure to analyze such dielectric spectra for soft particles, and then calculated the dielectric properties of the components of the SPBs (such as the permittivities and conductivities of the layer and solution phase), especially the layer thickness d s of the polyelectrolyte chain (PE) layer. We also found a larger confinement degree of counterions in the PAEMH brush due to the protonation of the amino group. Moreover, the repulsive force between the SPB particles is evaluated by using the d s combined with the relative theoretical formulas. We conclude that by raising (reducing) the acidity of the system, the stability of the PAEMH-SPB (PAA-SPB) suspension was improved. An increase in particle concentration can also improve the stability of these two dispersions.
Turbulence Modulation by Non-Spherical Particles
DEFF Research Database (Denmark)
Mandø, Matthias
. This study encompass an outlook on existing work, an experimental study, development of a numerical model and a case study advancing the modeling techniques for pulverized coal combustion to deal with larger non-spherical biomass particles. Firstly, existing knowledge concerning the motion of non...... of non-spherical particles. Secondly, an extensive parametric study concerning the measurement of turbulence intensity in a particle-laden jet compared to that of a clear jet has been undertaken. The effect of three different sizes of spherical particles as well as two distinct non-spherical shapes...... from the interaction with particles. Validation, using existing measurements as well as those obtained for the particle-laden jet, demonstrate that the new model is able to predict the experimentally observed tendencies and thus represent an improvement compared to existing models. The additional...
Automated spherical aberration correction in scanning confocal microscopy
Yoo, H.W.; Royen, M.E.; van Cappellen, W.A.; Houtsmuller, A.B.; Verhaegen, M.H.G.; Schitter, G.
2014-01-01
Mismatch between the refractive indexes of immersion media and glass coverslips introduces spherical aberrations in microscopes especially for high numerical aperture objectives. This contribution demonstrates an automated adjustment of the coverslip correction collar in scanning confocal microscopy
FY 2008 Miniature Spherical Retroreflectors – Final Report
Energy Technology Data Exchange (ETDEWEB)
Anheier, Norman C.; Bernacki, Bruce E.; Klymyshyn, Nicholas A.; Krishnaswami, Kannan; Rodriguez, Carmen P.
2009-02-01
Through the duration of the NNSA Office of Nuclear Nonproliferation Research and Development (NA-22) Miniature Spherical Retroreflectors lifecycle project, our research team focused on developing solutions to the fabrication bottleneck that has inhibited development and deployment of wide-angle optically interrogated chemical and radiological remote sensing technology. Our team advanced the concept of step-index clad retroreflectors to approximate an optimized, but yet unrealized spherical gradient index design. An intensive numerical simulation effort was undertaken that resulted in optimized step-index optical designs for mid-infrared applications. Geometric optics ray trace modeling was performed to better understand the geometrical dependencies of the miniature spherical retroreflector application. We adopted and advanced the concept of optical cross section, a metric that provides relative performance comparisons between different retroreflector designs and our cross-section analysis demonstrated that our step-index design provided 90% of the range capacity of the ideal spherical index design.
Spherical robot of combined type: Dynamics and control
Kilin, Alexander A.; Pivovarova, Elena N.; Ivanova, Tatyana B.
2015-11-01
This paper is concerned with free and controlled motions of a spherical robot of combined type moving by displacing the center of mass and by changing the internal gyrostatic momentum. Equations of motion for the nonholonomic model are obtained and their first integrals are found. Fixed points of the reduced system are found in the absence of control actions. It is shown that they correspond to the motion of the spherical robot in a straight line and in a circle. A control algorithm for the motion of the spherical robot along an arbitrary trajectory is presented. A set of elementary maneuvers (gaits) is obtained which allow one to transfer the spherical robot from any initial point to any end point.
Spherically symmetric brane spacetime with bulk f(R) gravity
Energy Technology Data Exchange (ETDEWEB)
Chakraborty, Sumanta [IUCAA, Ganeshkhind, Pune University Campus, Post Bag 4, Pune (India); SenGupta, Soumitra [Indian Association for the Cultivation of Science, Department of Theoretical Physics, Kolkata (India)
2015-01-01
Introducing f(R) term in the five-dimensional bulk action we derive effective Einstein's equation on the brane using Gauss-Codazzi equation. This effective equation is then solved for different conditions on dark radiation and dark pressure to obtain various spherically symmetric solutions. Some of these static spherically symmetric solutions correspond to black hole solutions, with parameters induced from the bulk. Specially, the dark pressure and dark radiation terms (electric part of Weyl curvature) affect the brane spherically symmetric solutions significantly. We have solved for one parameter group of conformal motions where the dark radiation and dark pressure terms are exactly obtained exploiting the corresponding Lie symmetry. Various thermodynamic features of these spherically symmetric space-times are studied, showing existence of second order phase transition. This phenomenon has its origin in the higher curvature term with f(R) gravity in the bulk. (orig.)
Trapped ion imaging with a high numerical aperture spherical mirror
Energy Technology Data Exchange (ETDEWEB)
Shu, G; Dietrich, M R; Kurz, N; Blinov, B B, E-mail: shugang@u.washington.ed [Department of Physics, University of Washington, Seattle, WA 98105-1560 (United States)
2009-08-14
Efficient collection and analysis of trapped ion qubit fluorescence is essential for robust qubit state detection in trapped ion quantum computing schemes. We discuss simple techniques of improving photon collection efficiency using high numerical aperture (N.A.) reflective optics. To test these techniques we placed a spherical mirror with an effective N.A. of about 0.9 inside a vacuum chamber in the vicinity of a linear Paul trap. We demonstrate stable and reliable trapping of single barium ions, in excellent agreement with our simulations of the electric field in this setup. While a large N.A. spherical mirror introduces significant spherical aberration, the ion image quality can be greatly improved by a specially designed aspheric corrector lens located outside the vacuum system. Our simulations show that the spherical mirror/corrector design is an easy and cost-effective way to achieve high photon collection rates when compared to a more sophisticated parabolic mirror setup.
Photodetachment of H- near a Hard Spherical Surface
Institute of Scientific and Technical Information of China (English)
M. Haneef; Iftikhar Ahmad; A. Afaq; A. Rahman
2012-01-01
The photodetachment of a hydrogen negative ion (H- ) near a hard spherical surface is investigated by using the theoretical imaging method. The surface is oriented in such a fashion that the laser polarization direction is perpendicular to the principal axis of the spherical surface. Analytical expressions are derived for the detached-electron flux and photodetachment cross section. Strong interference patterns are observed in the detached-electron flux, while no visible oscillations are found in the photodetachment cross section.%The photodetachment of a hydrogen negative ion (H-) near a hard spherical surface is investigated by using the theoretical imaging method.The surface is oriented in such a fashion that the laser polarization direction is perpendicular to the principal axis of the spherical surface.Analytical expressions are derived for the detachedelectron flux and photodetachment cross section.Strong interference patterns are observed in the detachedelectron flux,while no visible oscillations are found in the photodetachment cross section.
Dynamics of a Spherical Null Shell within the Distributional Formalism
Khakshournia, Samad; Mansouri, Reza
2004-01-01
Dynamics of a null thin shell immersed in a generic spherically symmetric spacetime is obtained within the distributional formalism. It has been shown that the distributional formalism leads to the same result as in the conventional formalism.
Cavity method in the spherical Sherrington-Kirkpatrick model
Panchenko, Dmitry
2006-01-01
We develop a cavity method in the spherical Sherrington-Kirkpatrick model at high temperature and small external field. As one application we compute the limit of the covariance matrix for fluctuations of the overlap and magnetization.
An Approximate Solution for Spherical and Cylindrical Piston Problem
Indian Academy of Sciences (India)
S K Singh; V P Singh
2000-02-01
A new theory of shock dynamics (NTSD) has been derived in the form of a finite number of compatibility conditions along shock rays. It has been used to study the growth and decay of shock strengths for spherical and cylindrical pistons starting from a non-zero velocity. Further a weak shock theory has been derived using a simple perturbation method which admits an exact solution and also agrees with the classical decay laws for weak spherical and cylindrical shocks.
Electrical Characterization of Spherical Copper Oxide Memristive Array Sensors
2014-03-27
running, dinner-table debate etiquette, sailing, electric guitar, and the Seattle bus system, but only earned his Bachelor of Science in Electrical ... ELECTRICAL CHARACTERIZATION OF SPHERICAL COPPER OXIDE MEMRISTIVE ARRAY SENSORS THESIS James P. Orta, Second Lieutenant, USAF AFIT-ENP-14-M-40...not subject to copyright protection in the United States. AFIT-ENP-14-M-40 ELECTRICAL CHARACTERIZATION OF SPHERICAL COPPER OXIDE MEMRISTIVE ARRAY
Towards AN Easier Orientation for Spherical Photogrammetry
Fangi, G.
2015-02-01
For architectural metric documentation, Spherical Photogrammetry (SP) has demonstrated its validity and efficiency in many projects already. The speed of surveying is high, the accuracy and completeness of the plotting are satisfactory. However, there are still many problems to be solved. The weakest point is the orientation procedure, which is rather difficult to perform, in the sense that only very experienced people can run it, and few people only make use of it. The old orientation steps are 1) model formation (limited to binocular panoramas couples); 2) link of all the models in a block adjustment with independent model triangulation; 3) block bundle adjustment with 4 parameters/pano (3 coord.+1 orientation bearing); 4) block bundle adjustment with 6 parameters/pano, say the previous 4 + 2 correction angles around the horizontal axes. The panoramas must be spherical and quasi-horizontal. In order to make easier the orientation, enabling more people to use SP, an improved approach has been set up. It consists in the combination of any possible model formed either by three and two panoramas. The trinocular vision, say the combination of three different panoramas to form a unique model, has the advantage to be much more robust in comparison to binocular vision in the sense that the trinocular model is likely to be more error-free than any of the three composing binocular models. It contains less model deformation, the model coordinates are validated by the mutual comparison of the three intersecting binocular models. In addition, the number of possible trinocular models is normally much larger than the one of binocular models. The steps for a semi-automatic orientation of a block of panoramas proceed as follows: - Form any possible trinocular models by combination of the panoramas; - in case that no trinocular model has been formed, form any possible binocular model; - run a block adjustment with the algorithm of independent model, to link together the models in
TOWARDS AN EASIER ORIENTATION FOR SPHERICAL PHOTOGRAMMETRY
Directory of Open Access Journals (Sweden)
G. Fangi
2015-02-01
Full Text Available For architectural metric documentation, Spherical Photogrammetry (SP has demonstrated its validity and efficiency in many projects already. The speed of surveying is high, the accuracy and completeness of the plotting are satisfactory. However, there are still many problems to be solved. The weakest point is the orientation procedure, which is rather difficult to perform, in the sense that only very experienced people can run it, and few people only make use of it. The old orientation steps are 1 model formation (limited to binocular panoramas couples; 2 link of all the models in a block adjustment with independent model triangulation; 3 block bundle adjustment with 4 parameters/pano (3 coord.+1 orientation bearing; 4 block bundle adjustment with 6 parameters/pano, say the previous 4 + 2 correction angles around the horizontal axes. The panoramas must be spherical and quasi-horizontal. In order to make easier the orientation, enabling more people to use SP, an improved approach has been set up. It consists in the combination of any possible model formed either by three and two panoramas. The trinocular vision, say the combination of three different panoramas to form a unique model, has the advantage to be much more robust in comparison to binocular vision in the sense that the trinocular model is likely to be more error-free than any of the three composing binocular models. It contains less model deformation, the model coordinates are validated by the mutual comparison of the three intersecting binocular models. In addition, the number of possible trinocular models is normally much larger than the one of binocular models. The steps for a semi-automatic orientation of a block of panoramas proceed as follows: - Form any possible trinocular models by combination of the panoramas; - in case that no trinocular model has been formed, form any possible binocular model; - run a block adjustment with the algorithm of independent model, to link together
Application of spherical micro diodes for brachytherapy dosimetry
Energy Technology Data Exchange (ETDEWEB)
Broisman, Andrey, E-mail: andreybr@ariel.ac.i [Medical Physics, Ariel University Center, Ariel 40700 (Israel); Shani, Gad [Biomedical Engineering, Ben Gurion University, P.O. Box 653, Beer Sheva 84105 (Israel)
2011-03-15
The research presented in this paper demonstrates the feasibility and the advantages of using spherical micro diodes for radiation dosimetry. The spherical symmetry of the diode response is demonstrated, compared to that of planar diodes. The application of the spherical diode described here is for radiotherapy dosimetry, particularly brachytherapy. Measurements were done in PMMA phantoms. The advantage of the spherical diode is that it can be used for radiation measurement in a 4{pi} geometry, it was demonstrated by measurements in both axial and azimuthal planes. The diodes were found to respond equally to radiation coming from all directions, directly from the source or due to scattered radiation within the medium. In the present work 1.8 mm diameter silicone diodes were used. The small size of these spherical diodes provides local dose measurement and can be used for in situ dosimetry while treatment takes place. Treatment planning correction can be made accordingly. Commercially available seeds of the isotopes I{sup 125} and Pd{sup 103} were used as radiation sources. The spherical diodes response was compared with that of planar diodes XRB generally used for UV and X-ray dosimetry, and with TLD measurements. We have also compared the measured results with Monte Carlo simulation, applying the MCNP code and with calculations shown in the TG-43 report.
ALGORITHM FOR SPHERICITY ERROR AND THE NUMBER OF MEASURED POINTS
Institute of Scientific and Technical Information of China (English)
HE Gaiyun; WANG Taiyong; ZHAO Jian; YU Baoqin; LI Guoqin
2006-01-01
The data processing technique and the method determining the optimal number of measured points are studied aiming at the sphericity error measured on a coordinate measurement machine (CMM). The consummate criterion for the minimum zone of spherical surface is analyzed first, and then an approximation technique searching for the minimum sphericity error from the form data is studied. In order to obtain the minimum zone of spherical surface, the radial separation is reduced gradually by moving the center of the concentric spheres along certain directions with certain steps. Therefore the algorithm is precise and efficient. After the appropriate mathematical model for the approximation technique is created, a data processing program is developed accordingly. By processing the metrical data with the developed program, the spherical errors are evaluated when different numbers of measured points are taken from the same sample, and then the corresponding scatter diagram and fit curve for the sample are graphically represented. The optimal number of measured points is determined through regression analysis. Experiment shows that both the data processing technique and the method for determining the optimal number of measured points are effective. On average, the obtained sphericity error is 5.78 μm smaller than the least square solution,whose accuracy is increased by 8.63%; The obtained optimal number of measured points is half of the number usually measured.
A static spherically symmetric thin shell wormhole colliding with a spherical thin shell
Gao, Sijie
2015-01-01
We consider a static spherically symmetric thin shell wormhole collides with another thin shell consisting of ordinary matter. By employing the geometrical constraint, which leads to the conservation of energy and momentum, we show that the state after the collision can be solved from the initial data. In the low speed approximation, the solutions are rather simple. The shell may either bounce back or pass through the wormhole. In either case, the wormhole shrinks right after the collision. In the ``bouncing'' case, a surprising result is that the radial speeds before and after the collision satisfy an addition law, which is independent of the masses of the wormhole and the shell. Once the shell passes through the wormhole, we find that the shell always expands. However, the expansion rate is the same as its collapsing rate right before the collision. Finally, we find out the solution for the shell moving together with the wormhole.
Spherical grating based x-ray Talbot interferometry
Energy Technology Data Exchange (ETDEWEB)
Cong, Wenxiang, E-mail: congw@rpi.edu, E-mail: xiy2@rpi.edu, E-mail: wangg6@rpi.edu; Xi, Yan, E-mail: congw@rpi.edu, E-mail: xiy2@rpi.edu, E-mail: wangg6@rpi.edu; Wang, Ge, E-mail: congw@rpi.edu, E-mail: xiy2@rpi.edu, E-mail: wangg6@rpi.edu [Biomedical Imaging Center, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)
2015-11-15
Purpose: Grating interferometry is a state-of-the-art x-ray imaging approach, which can acquire information on x-ray attenuation, phase shift, and small-angle scattering simultaneously. Phase-contrast imaging and dark-field imaging are very sensitive to microstructural variation and offers superior contrast resolution for biological soft tissues. However, a common x-ray tube is a point-like source. As a result, the popular planar grating imaging configuration seriously restricts the flux of photons and decreases the visibility of signals, yielding a limited field of view. The purpose of this study is to extend the planar x-ray grating imaging theory and methods to a spherical grating scheme for a wider range of preclinical and clinical applications. Methods: A spherical grating matches the wave front of a point x-ray source very well, allowing the perpendicular incidence of x-rays on the grating to achieve a higher visibility over a larger field of view than the planer grating counterpart. A theoretical analysis of the Talbot effect for spherical grating imaging is proposed to establish a basic foundation for x-ray spherical gratings interferometry. An efficient method of spherical grating imaging is also presented to extract attenuation, differential phase, and dark-field images in the x-ray spherical grating interferometer. Results: Talbot self-imaging with spherical gratings is analyzed based on the Rayleigh–Sommerfeld diffraction formula, featuring a periodic angular distribution in a polar coordinate system. The Talbot distance is derived to reveal the Talbot self-imaging pattern. Numerical simulation results show the self-imaging phenomenon of a spherical grating interferometer, which is in agreement with the theoretical prediction. Conclusions: X-ray Talbot interferometry with spherical gratings has a significant practical promise. Relative to planar grating imaging, spherical grating based x-ray Talbot interferometry has a larger field of view and
Akbar, M. M.
2017-06-01
It is well known that static spherically symmetric spacetimes can admit foliations by flat spacelike hypersurfaces, which are best described in terms of the Painlevè-Gullstrand coordinates. The uniqueness and existence of such foliations were addressed earlier. In this paper, we prove, purely geometrically, that any possible foliation of a static spherically symmetric spacetime by an arbitrary codimension-one spherical spacelike geometry, up to time translation and rotation, is unique, and we find the algebraic condition under which it exists. This leads us to what can be considered as the most natural generalization of the Painlevè-Gullstrand coordinate system for static spherically symmetric metrics, which, in turn, makes it easy to derive generic conclusions on foliation and to study specific cases as well as to easily reproduce previously obtained generalizations as special cases. In particular, we note that the existence of foliation by flat hypersurfaces guarantees the existence of foliation by hypersurfaces whose Ricci curvature tensor is everywhere non-positive (constant negative curvature is a special case). The study of uniqueness and the existence concurrently solves the question of embeddability of a spherical spacelike geometry in one-dimensional higher static spherically symmetric spacetimes, and this produces known and new results geometrically, without having to go through the momentum and Hamiltonian constraints.
Institute of Scientific and Technical Information of China (English)
徐萌; 郭凤霞; 司法启; 梁立峰; 倪惠珍; 王海玲
2013-01-01
目的:降低不合理用药率,提高临床合理用药水平.方法:选取我院588名医师2010年第1、2季度病历共2 940份,采用柏拉图分析法对其中的不合理用药情况进行解析,找出关键的影响因素,采取切实可行的应对措施,再与改进后的2011年第1、2季度的2 940份病历相关情况进行比较.结果:我院不合理用药的类型包括用药时机不当、用药疗程不当等,并主要体现在围手术期用药时,影响因素涉及未及时进行病原学检查和药敏试验、未区分预防和治疗用药等；通过采取提高认识、知识培训、完善资料等措施,不合理用药发生频数由改进前的4 003例次下降到1 814例次,不合理用药分类的15项中有13项指标显著下降(P＜0.05).结论:柏拉图分析法可量化临床药师各项活动和考评临床药学服务效果,可提高医院临床合理用药水平.%OBJECTIVE: To reduce the incidence of irrational drug use and improve rational use of drugs in the clinic. METHODS: 2 940 medical records were collected from 588 physicians of our hospital in the first and second quarter of 2010. Irrational drug use was analyzed by Platonic analysis to find out important influential factors and carry out the feasible corresponding measures, and then compared with 2 940 medical records collected in the first and second quarter of 2011. RESULTS: Irrational drug use of our hospital included inappropriate medication time, improper treatment course, and so on, which was mainly reflected in aspect of perioperative medication; influential factors involved etiological examination and drug sensitive test behind time, confusion between prophylactic medication and therapeutic medication, etc. After enhancing understanding, training, perfecting information and other measures, the number of irrational drug use decreased from 4 003 to 1 814, and that of 13 items decreased sharply among 15 items of irrational drug use (P<0.05). CONCLUSIONS: Platonic
Institute of Scientific and Technical Information of China (English)
朱璇璇; 黄凌燕
2013-01-01
诺姆·乔姆斯基是杰出的美国语言学家、政治活动家、哲学家和思想家，其一生的研究方向主要集中在两个方面：数理语言学和政治评论，即“柏拉图问题”（Platonic Problem）和“奥威尔问题”（Orwellian Problem）。通过解读乔姆斯基语言学和政治学二者之间确实存在某种微妙的关系--关于人的本质（human nature）的研究，并就乔姆斯基关于人的本质的主要观点为出发点，探讨和研究乔姆斯基对“柏拉图问题”和“奥威尔问题”的看法。%Noam Chomsky is the distinguished linguists, politician, philosopher and ideologist, whose research has focused on two aspects: mathematical linguistics and political criticism, that is, a research of the solution to Platonic Problem and Orwellian Problem. The essay will find out certain delicate relationship between Chomsky’s linguistic ideas and political thought, and both Platonic Problem and Orwellian Problem are subsumed under research on human nature, from which the author will explore both problems more deeply and thoroughly.
Directory of Open Access Journals (Sweden)
Kohei Arai
2012-06-01
Full Text Available Simulation method of sea water which contains spherical and non-spherical particles of suspended solid and phytoplankton based on Monte Carlo Ray Tracing: MCRT is proposed for identifying non-spherical species of phytoplankton. From the simulation results, it is found that the proposed MCRT model is validated. Also some possibility of identification of spherical and non-spherical shapes of particles which are contained in sea water is shown. Meanwhile, simulations with the different shape of particles, Prolate and Oblate show that Degree of Polarization: DP depends on shapes. Therefore, non-spherical shape of phytoplankton can be identified with polarization characteristics measurements of the ocean.
Comparative study of"imitation theory"--from Platon to Aristotle%“模仿说”比较研究——从柏拉图到亚里士多德
Institute of Scientific and Technical Information of China (English)
胡安奇
2012-01-01
“模仿”历来是西方文论和美学史的一条主线，它贯穿于文论和美学的始终。众多的模仿说当中，古希腊柏拉图建立在“理念论”之上的模仿说和亚里士多德“艺术模仿现实”的唯物主义模仿说尤其光彩夺目，他们共同奠定了西方美学、文论的理论基础。本文简要回顾了柏拉图和亚氏模仿说的基本内涵，并对这两种模仿说进行简略的比较，最后小结柏拉图和亚氏师徒二人在模仿说理论上产生分歧的原因。% "Imitation"has always been the masterstroke of western literary theory and aesthetics history, it runs through in literary theory and aesthetics. In many imitation, ancient Greek Platon’s"imitation theory"built on the"theory of idea"and Aristotle’s materialism imitating of"art imitating reality"is especially bright, together they laid the theory foundation of western aesthetics and literary theory. This paper presents the basic connotation of Platon and Asia 's imitation theory, and a simple comparison between the two kind of imitation theory, finally summarizes the reasons of divergence.
Chu, K; Rasmussen, B
2012-06-01
To review the issues a physicist may encounter in a community hospital during the transition from film/paper charts to a paperless environment with ARIA and a TrueBeam LINAC. With a lean budget, it was necessary for the physics group to take on the project management responsibilities in order save costs. This work highlights the lessons learned during the planning and execution of our project. Like many hospitals around the county, our hospital was caught in the economic downturn and was unable to provide all of the capital necessary to upgrade to the radiation oncology department. However, with the support of the hospital foundation, a total of $6M was secured for new LINAC, ARIA and CT simulator. To save costs on facilities and computers, it was necessary for the physics group to be involved in creating architectural drawings for shielding calculations, finding a vendor to remove the old linac, assisting the foundation to raise money, submission of the 'Certificate of Need' approval with the state, negotiation with vendors, IT infrastructure, reviews with the general contractor and vendor's project team, and ultimately writing the commissioning reports for the new systems as well as developing new policies and procedures. During a period of 4 months, the old LINAC was removed, facility renovations made, the TrueBeam linac was installed, accepted, and commissioned and first patients were treated. In addition, we transitioned from a film/paper environment to a paperless environment. However, this was very stressful for staff and it may be advisable to stage such a project over a longer period of time. There was also significant lost revenue (∼$2M) during downtime of construction, installation, and commissioning. The radiation oncology department was upgraded (The Beauty) on a tight budget but at the cost of added stress (The Beast) to the staff. © 2012 American Association of Physicists in Medicine.
Optofluidic encapsulation of crystalline colloidal arrays into spherical membrane.
Kim, Shin-Hyun; Jeon, Seog-Jin; Yang, Seung-Man
2008-05-07
Double emulsion droplets encapsulating crystalline colloidal arrays (CCAs) with a narrow size distribution were produced using an optofluidic device. The shell phase of the double emulsion was a photocurable resin that was photopolymerized downstream of the fluidic channel within 1 s after drop generation. The present optofluidic synthesis scheme was very effective for fabricating highly monodisperse spherical CCAs that were made structurally stable by in situ photopolymerization of the encapsulating shells. The shell thickness and the number of core emulsion drops could be controlled by varying the flow rates of the three coflowing streams in the dripping regime. The spherical CCAs confined in the shell exhibited distinct diffraction patterns in the visible range, in contrast to conventional film-type CCAs. As a result of their structure, the spherical CCAs exhibited photonic band gaps for normal incident light independent of the position on the spherical surface. This property was induced by heterogeneous nucleation at the smooth wall of the spherical emulsion drop during crystallization into a face-centered cubic (fcc) structure. On the other hand, the solidified shells did not permit the penetration of ionic species, enabling the CCAs to maintain their structure in a continuous aqueous phase of high ionic strength for at least 1 month. In addition, the evaporation of water molecules inside the shell was slowed considerably when the core-shell microparticles were exposed to air: It took approximately 6 h for a suspension encapsulated in a thick shell to evaporate completely, which is approximately 1000 times longer than the evaporation time for water droplets with the same volume. Finally, the spherical CCAs additionally exhibited enhanced stability against external electric fields. The spherical geometry and high dielectric constant of the suspension contributed to reducing the electric field inside the shell, thereby inhibiting the electrophoretic movement of
Source distance determination based on the spherical harmonics
Koutny, Adam; Jiricek, Ondrej; Thomas, Jean-Hugh; Brothanek, Marek
2017-02-01
This paper deals with the processing of signals measured by a spherical microphone array, focusing on the utilization of near-field information of such an array. The processing, based on the spherical harmonics decomposition, is performed in order to investigate the radial-dependent spherical functions and extract their argument - distance to the source. Using the low-frequency approximation of these functions, the source distance is explicitly expressed. The source distance is also determined from the original equation (using no approximation) by comparing both sides of this equation. The applicability of both methods is first presented in the noise-less data simulation, then validated with data contaminated by the additive white noise of different signal-to-noise ratios. Finally, both methods are tested for real data measured by a rigid spherical microphone array of radius 0.15 m, consisting of 36 microphones for a point source represented by a small speaker. The possibility of determination of the source distance using low-order spherical harmonics is shown.
Richtmyer - Meshkov instability in a spherical target with density variation
Mandal, Labakanta; Banerjee, Rahul; Khan, Manoranjan; Gupta, M R
2011-01-01
The motion of unstable fluid interface due to Richtmyer - Meshkov (RM) instability incorporating with density variation has been studied in a spherical target using Lagrangian formulation. During the compression in Inertial Confinement Fusion (ICF)process, the density of deuterium - tritium (DT) fuel increases 1000 times greater than the density of gaseous DT fuel within the core of spherical target. We have extended the feature of density variation [PRA,84-Mikaelian & Lindl] in spherical geometry.Due to convergent shock impingement, the perturbed interface will be nonspherical which leads to the density variation in both radial as well as in polar angle. We have shown that the interface of perturbed surface decreases with time to reach a minimum and then kick back to gradual increase. As the perturbed radius decreases, the density increases and reaches a maxima corresponding to a minima of perturbed radius. This is the practical situation of density characteristics during implosion of ICF. The numerical ...
Symmetries and deformations in the spherical shell model
Van Isacker, P.; Pittel, S.
2016-02-01
We discuss symmetries of the spherical shell model that make contact with the geometric collective model of Bohr and Mottelson. The most celebrated symmetry of this kind is SU(3), which is the basis of Elliott’s model of rotation. It corresponds to a deformed mean field induced by a quadrupole interaction in a single major oscillator shell N and can be generalized to include several major shells. As such, Elliott’s SU(3) model establishes the link between the spherical shell model and the (quadrupole component of the) geometric collective model. We introduce the analogue symmetry induced by an octupole interaction in two major oscillator shells N-1 and N, leading to an octupole-deformed solution of the spherical shell model. We show that in the limit of large oscillator shells, N\\to ∞ , the algebraic octupole interaction tends to that of the geometric collective model.
Plane-wave decomposition by spherical-convolution microphone array
Rafaely, Boaz; Park, Munhum
2001-05-01
Reverberant sound fields are widely studied, as they have a significant influence on the acoustic performance of enclosures in a variety of applications. For example, the intelligibility of speech in lecture rooms, the quality of music in auditoria, the noise level in offices, and the production of 3D sound in living rooms are all affected by the enclosed sound field. These sound fields are typically studied through frequency response measurements or statistical measures such as reverberation time, which do not provide detailed spatial information. The aim of the work presented in this seminar is the detailed analysis of reverberant sound fields. A measurement and analysis system based on acoustic theory and signal processing, designed around a spherical microphone array, is presented. Detailed analysis is achieved by decomposition of the sound field into waves, using spherical Fourier transform and spherical convolution. The presentation will include theoretical review, simulation studies, and initial experimental results.
Resonance energy transfer: The unified theory via vector spherical harmonics.
Grinter, Roger; Jones, Garth A
2016-08-21
In this work, we derive the well-established expression for the quantum amplitude associated with the resonance energy transfer (RET) process between a pair of molecules that are beyond wavefunction overlap. The novelty of this work is that the field of the mediating photon is described in terms of a spherical wave rather than a plane wave. The angular components of the field are constructed in terms of vector spherical harmonics while Hankel functions are used to define the radial component. This approach alleviates the problem of having to select physically correct solution from non-physical solutions, which seems to be inherent in plane wave derivations. The spherical coordinate system allows one to easily decompose the photon's fields into longitudinal and transverse components and offers a natural way to analyse near-, intermediate-, and far-zone RET within the context of the relative orientation of the transition dipole moments for the two molecules.
Exact and asymptotic black branes with spherical compactification
Chopovsky, Alexey; Zhuk, Alexander
2012-01-01
In the six-dimensional Kaluza-Klein model with the multidimensional cosmological constant $\\Lambda_6$, we obtain the black brane with spherical compactification of the internal space. The matter source for this exact solution consists of two parts. First, it is a fine-tuned homogeneous perfect fluid which provides spherical compactification of the internal space. Second, it is a gravitating massive body with the dustlike equation of state in the external space and tension $\\hat p_1=-(1/2)\\hat\\varepsilon$ in the internal space. This solution exists both in the presence and absence of $\\Lambda_6$. In the weak-field approximation, we also get solutions of the linearized Einstein equations for the model with spherical compactification. Here, the gravitating matter source has the dustlike equation of state in the external space and an arbitrary equation of state $\\hat p_1=\\Omega \\hat\\varepsilon$ in the internal space. In the case $\\Lambda_6>0$ and $\\Omega\
A Helium Atom Confined by a Spherical Gaussian Potential Well
Institute of Scientific and Technical Information of China (English)
QIU Liang; XIE Wen-Fang; WANG An-Min
2008-01-01
The helium atom confined by a non-impenetrable spherical box, i.e., a spherical Gaussian potential well which possesses finite height and range, is studied employing the exact diagonalization method. Total energies of the ground and three low-excited states are obtained as a function of the confined potential radii. We find that the confinement may cause accidental degeneracies between levels with different low-excited states and the inversion of the energy values. The results for the three-dimensional spherical potential well and the two-dimensional disc-like potential well are compared with each other: in general, the energies of the states decrease and the energy intervals between states increase with the reduction of the space dimensions.
Analysis of spherical thermo-acoustic radiation in gas
Directory of Open Access Journals (Sweden)
Hanping Hu
2012-09-01
Full Text Available A general solution of the spherical thermo-acoustic (TA radiation from any solid in gas is derived by using a fully thermally-mechanically coupled TA model. Therefore, the characteristics and regularities of spherical TA emission can be studied more completely. It is shown that flat amplitude-frequency response, the most important feature for planar TA emission from technical standpoint, still exists for spherical TA emission, and changes with the radius of a sphere, thickness of TA sample, and the distance from surface. This expression agrees well with experimental and theoretical results of planer TA emission for much larger sphere and lays the foundation to calculate complex TA emission problems.
A Non-axisymmetric Spherical α2-Dynamo
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Using the Chebyshev-tau method, the generation of oscillatory nonaxisymmetric stellar magnetic fields by the α2-dynamo is studied in spherical geometry. Following the boundary conditions given by Schubert & Zhang, the spherical α2-dynamo consists of a fully convective spherical shell with inner radius ri and outer radius ro. A comparison of the critical dynamo numbers of axisymmetric and φ-dependent modes for different thicknesses of the convective shell and different α-profiles leads to the following qualitative results: (I) when the angular factor of α-profile is sinnθ cosθ (n = 1, 2, 4) the solutions of the α2-dynamo are oscillatory and non-axisymmetric, (ii) the thinner the convective shell, the more easily is the nonaxisymmetric mode excited and the higher is the latitudinal wave number, (iii) the thickness of the outer convective shell has an effect on the symmetries of the magnetic fields.
Mechanisms of Stochastic Diffusion of Energetic Ions in Spherical Tori
Energy Technology Data Exchange (ETDEWEB)
Ya.I. Kolesnichenko; R.B. White; Yu.V. Yakovenko
2001-01-18
Stochastic diffusion of the energetic ions in spherical tori is considered. The following issues are addressed: (I) Goldston-White-Boozer diffusion in a rippled field; (ii) cyclotron-resonance-induced diffusion caused by the ripple; (iii) effects of non-conservation of the magnetic moment in an axisymmetric field. It is found that the stochastic diffusion in spherical tori with a weak magnetic field has a number of peculiarities in comparison with conventional tokamaks; in particular, it is characterized by an increased role of mechanisms associated with non-conservation of the particle magnetic moment. It is concluded that in current experiments on National Spherical Torus eXperiment (NSTX) the stochastic diffusion does not have a considerable influence on the confinement of energetic ions.
Orthogonal basis for spherical monogenics by step two branching
Lavicka, R; Van Lancker, P
2010-01-01
Spherical monogenics can be regarded as a basic tool for the study of harmonic analysis of the Dirac operator in Euclidean space R^m. They play a similar role as spherical harmonics do in case of harmonic analysis of the Laplace operator on R^m. Fix the direct sum R^m = R^p x R^q. In this paper we will study the decomposition of the space M_n(R^m;C_m) of spherical monogenics of order n under the action of Spin(p) x Spin(q). As a result we obtain a Spin(p) x Spin(q)-invariant orthonormal basis for M_n(R^m;C_m). In particular, using the construction with p = 2 inductively, this yields a new orthonormal basis for the space M_n(R^m;C_m).
Preparation of spherical cobalt carbonate powder with high tap density
Institute of Scientific and Technical Information of China (English)
XIAO Jin; WANG Jian-feng; LIU Yong-dong; LI Jie; LIU Ye-xiang
2006-01-01
Spherical cobalt carbonate with high tap density, good crystallization and uniform particle size was prepared by controlled chemical crystal method using cobalt chloride and ammonium bicarbonate as cobalt source and precipitator. The effects of pH value and reaction time on crystallization and physical properties of cobalt carbonate were studied. The results show that the key factors influencing the preparation process of spherical cobalt carbonate with high tap density and good crystallization are how to control pH value (7.25 ± 0.05) and keep some reaction time (about 10 h). Co4O3 was prepared by sintering spherical morphology CoCO3 samples at varied temperatures. The results show that as the decomposition temperature increases, the as-obtained Co4O3 products with porous structure transform into polyhedral structure with glazed surface, and simultaneously the cobalt content and tap density increase. However, the specific surface area shows a trend of decrease.
Multi-level spherical moments based 3D model retrieval
Institute of Scientific and Technical Information of China (English)
LIU Wei; HE Yuan-jun
2006-01-01
In this paper a novel 3D model retrieval method that employs multi-level spherical moment analysis and relies on voxelization and spherical mapping of the 3D models is proposed. For a given polygon-soup 3D model, first a pose normalization step is done to align the model into a canonical coordinate frame so as to define the shape representation with respect to this orientation. Afterward we rasterize its exterior surface into cubical voxel grids, then a series of homocentric spheres with their center superposing the center of the voxel grids cut the voxel grids into several spherical images. Finally moments belonging to each sphere are computed and the moments of all spheres constitute the descriptor of the model. Experiments showed that Euclidean distance based on this kind of feature vector can distinguish different 3D models well and that the 3D model retrieval system based on this arithmetic yields satisfactory performance.
Plane-wave decomposition by spherical-convolution microphone array
Rafaely, Boaz; Park, Munhum
2004-05-01
Reverberant sound fields are widely studied, as they have a significant influence on the acoustic performance of enclosures in a variety of applications. For example, the intelligibility of speech in lecture rooms, the quality of music in auditoria, the noise level in offices, and the production of 3D sound in living rooms are all affected by the enclosed sound field. These sound fields are typically studied through frequency response measurements or statistical measures such as reverberation time, which do not provide detailed spatial information. The aim of the work presented in this seminar is the detailed analysis of reverberant sound fields. A measurement and analysis system based on acoustic theory and signal processing, designed around a spherical microphone array, is presented. Detailed analysis is achieved by decomposition of the sound field into waves, using spherical Fourier transform and spherical convolution. The presentation will include theoretical review, simulation studies, and initial experimental results.
Reynolds stress and heat flux in spherical shell convection
Käpylä, P J; Guerrero, G; Brandenburg, A; Chatterjee, P
2010-01-01
Context. Turbulent fluxes of angular momentum and heat due to rotationally affected convection play a key role in determining differential rotation of stars. Aims. We compute turbulent angular momentum and heat transport as functions of the rotation rate from stratified convection. We compare results from spherical and Cartesian models in the same parameter regime in order to study whether restricted geometry introduces artefacts into the results. Methods. We employ direct numerical simulations of turbulent convection in spherical and Cartesian geometries. In order to alleviate the computational cost in the spherical runs and to reach as high spatial resolution as possible, we model only parts of the latitude and longitude. The rotational influence, measured by the Coriolis number or inverse Rossby number, is varied from zero to roughly seven, which is the regime that is likely to be realised in the solar convection zone. Cartesian simulations are performed in overlapping parameter regimes. Results. For slow ...
Montero, Pedro J
2012-01-01
Brown has recently introduced a covariant formulation of the BSSN equations which is well suited for curvilinear coordinate systems. This is particularly desirable as many astrophysical phenomena are symmetric with respect to the rotation axis or are such that curvilinear coordinates adapt better to their geometry. However, the singularities associated with such coordinate systems are known to lead to numerical instabilities unless special care is taken (e.g., regularization at the origin). Cordero-Carrion will present a rigorous derivation of partially implicit Runge-Kutta methods in forthcoming papers, with the aim of treating numerically the stiff source terms in wave-like equations that may appear as a result of the choice of the coordinate system. We have developed a numerical code solving the BSSN equations in spherical symmetry and the general relativistic hydrodynamic equations written in flux-conservative form. A key feature of the code is that it uses a second-order partially implicit Runge-Kutta me...
Plastic instabilities in statically and dynamically loaded spherical vessels
Energy Technology Data Exchange (ETDEWEB)
Duffey, Thomas A [Los Alamos National Laboratory; Rodriguez, Edward A [Los Alamos National Laboratory
2010-01-01
Significant changes were made in design limits for pressurized vessels in the 2007 version of the ASME Code (Section VIII, Div. 3) and 2008 and 2009 Addenda. There is now a local damage-mechanics based strain-exhaustion limit as well as the well-known global plastic collapse limit. Moreover, Code Case 2564 (Section VIII, Div. 3) has recently been approved to address impulsively loaded vessels. It is the purpose of this paper to investigate the plastic collapse limit as it applies to dynamically loaded spherical vessels. Plastic instabilities that could potentially develop in spherical shells under symmetric loading conditions are examined for a variety of plastic constitutive relations. First, a literature survey of both static and dynamic instabilities associated with spherical shells is presented. Then, a general plastic instability condition for spherical shells subjected to displacement controlled and impulsive loading is given. This instability condition is evaluated for six plastic and visco-plastic constitutive relations. The role of strain-rate sensitivity on the instability point is investigated. Calculations for statically and dynamically loaded spherical shells are presented, illustrating the formation of instabilities as well as the role of imperfections. Conclusions of this work are that there are two fundamental types of instabilities associated with failure of spherical shells. In the case of impulsively loaded vessels, where the pulse duration is short compared to the fundamental period of the structure, one instability type is found not to occur in the absence of static internal pressure. Moreover, it is found that the specific role of strain-rate sensitivity on the instability strain depends on the form of the constitutive relation assumed.
Uniform approximation from symbol calculus on a spherical phase space
Energy Technology Data Exchange (ETDEWEB)
Yu Liang, E-mail: liangyu@wigner.berkeley.edu [Department of Physics, University of California, Berkeley, CA 94720 (United States)
2011-12-16
We use symbol correspondence and quantum normal form theory to develop a more general method for finding uniform asymptotic approximations. We then apply this method to derive a result we announced in an earlier paper, namely the uniform approximation of the 6j-symbol in terms of the rotation matrices. The derivation is based on the Stratonovich-Weyl symbol correspondence between matrix operators and functions on a spherical phase space. The resulting approximation depends on a canonical, or area-preserving, map between two pairs of intersecting level sets on the spherical phase space. (paper)
PERFORATION OF PLASTIC SPHERICAL SHELLS UNDER IMPACT BY CYLINDRICAL PROJECTILES
Institute of Scientific and Technical Information of China (English)
NING Jian-guo; SONG Wei-dong
2006-01-01
The objective is to study the perforation of a plastic spherical shell impacted by a cylindrical projectile. First, the deformation modes of the shell were given by introducing an isometric transformation. Then, the perforation mechanism of the shell was analyzed and an analytical model was advanced. Based on Hamilton principle, the governing equation was obtained and solved using Runge-Kuta method. Finally, some important theoretical predictions were given to describe the perforation mechanism of the shell. The results will play an important role in understanding the perforation mechanism of spherical shells impacted by a projectile.
Newtonian and General Relativistic Models of Spherical Shells
Vogt, D
2009-01-01
A family of spherical shells with varying thickness is derived by using a simple Newtonian potential-density pair. Then, a particular isotropic form of a metric in spherical coordinates is used to construct a General Relativistic version of the Newtonian family of shells. The matter of these relativistic shells presents equal azimuthal and polar pressures, while the radial pressure is a constant times the tangential pressure. We also make a first study of stability of both the Newtonian and relativistic families of shells.
Construction of Aesthetic Spherical Patterns from Planar IFSs
Chen, Ning; Zhang, Yuting; Chung, K. W.
2016-07-01
To construct symmetrical patterns on the unit sphere from the planar iterative function systems (IFSs), we present a method of constructing IFSs with D3 symmetry which is composed of three-fold rotational symmetries together with reflections. An algorithm is developed to generate strange attractors with D3 symmetry on a triangular face and then project it onto the surface of the unit sphere to form aesthetics patterns with spherical symmetry. As an illustrative example, we consider the regular inscribed icosahedron in the unit sphere which contains 20 triangular faces. This method is valid to randomly generate aesthetic spherical patterns using planar IFSs.
Addition theorems for spin spherical harmonics: I. Preliminaries
Energy Technology Data Exchange (ETDEWEB)
Bouzas, Antonio O, E-mail: abouzas@mda.cinvestav.mx [Departamento de Fisica Aplicada, CINVESTAV-IPN, Carretera Antigua a Progreso Km. 6, Apdo. Postal 73 ' Cordemex' , Merida 97310, Yucatan (Mexico)
2011-04-22
We develop a systematic approach to deriving addition theorems for, and some other bilocal sums of, spin spherical harmonics. In this first part we establish some necessary technical results. We discuss the factorization of orbital and spin degrees of freedom in certain products of Clebsch-Gordan coefficients, and obtain general explicit results for the matrix elements in configuration space of tensor products of arbitrary rank of the position and angular-momentum operators. These results are the basis of the addition theorems for spin spherical harmonics obtained in part II (2011 J. Phys. A: Math. Theor. 44 165302).
Cubic versus spherical magnetic nanoparticles: the role of surface anisotropy.
Salazar-Alvarez, G; Qin, J; Sepelák, V; Bergmann, I; Vasilakaki, M; Trohidou, K N; Ardisson, J D; Macedo, W A A; Mikhaylova, M; Muhammed, M; Baró, M D; Nogués, J
2008-10-08
The magnetic properties of maghemite (gamma-Fe2O3) cubic and spherical nanoparticles of similar sizes have been experimentally and theoretically studied. The blocking temperature, T(B), of the nanoparticles depends on their shape, with the spherical ones exhibiting larger T(B). Other low temperature properties such as saturation magnetization, coercivity, loop shift or spin canting are rather similar. The experimental effective anisotropy and the Monte Carlo simulations indicate that the different random surface anisotropy of the two morphologies combined with the low magnetocrystalline anisotropy of gamma-Fe2O3 is the origin of these effects.
Strongly Localized Image States of Spherical Graphitic Particles
Directory of Open Access Journals (Sweden)
Godfrey Gumbs
2014-01-01
Full Text Available We investigate the localization of charged particles by the image potential of spherical shells, such as fullerene buckyballs. These spherical image states exist within surface potentials formed by the competition between the attractive image potential and the repulsive centripetal force arising from the angular motion. The image potential has a power law rather than a logarithmic behavior. This leads to fundamental differences in the nature of the effective potential for the two geometries. Our calculations have shown that the captured charge is more strongly localized closest to the surface for fullerenes than for cylindrical nanotube.
A parametric study on ice formation inside a spherical capsule
Energy Technology Data Exchange (ETDEWEB)
Ismail, K.A.R.; Silva, T.M. da [Depto. de Engenharia Termica e de Fluidos - FEM-UNICAMP CP: 6122, CEP 13083-970, SP, Campinas (Brazil); Henriquez, J.R. [Depto. de Engenharia Mecanica - DEMEC, UFPE, CEP 50740-530, PE, Recife (Brazil)
2003-09-01
This paper reports the results of a numerical study on the heat transfer during the process of solidification of water inside a spherical capsule. The governing equations of the problem and associated boundary conditions were formulated and solved using a finite difference approach and a moving grid scheme. The model was optimized and the numerical predictions were validated by comparison with experimental results realized by the authors. The model was also used to investigate the effects of the size and material of the shell, initial temperature of the phase change material and the external temperature of the spherical capsule on the solidified mass fraction and the time for the complete solidification. (authors)
Orthogonal fast spherical Bessel transform on uniform grid
Serov, Vladislav V.
2017-07-01
We propose an algorithm for the orthogonal fast discrete spherical Bessel transform on a uniform grid. Our approach is based upon the spherical Bessel transform factorization into the two subsequent orthogonal transforms, namely the fast Fourier transform and the orthogonal transform founded on the derivatives of the discrete Legendre orthogonal polynomials. The method utility is illustrated by its implementation for the problem of a two-atomic molecule in a time-dependent external field simulating the one utilized in the attosecond streaking technique.
Vibration Analysis of the Piezoelectric, Piezomagnetic Materials in Spherical Symmetry
Directory of Open Access Journals (Sweden)
Qun Guan
2013-01-01
Full Text Available Considering that the piezoelectric, piezomagnetic materials are in the spherical coordinate system and not accounting the body weight, body electric charge and body electric current, from the motion equation, gradient equation and the piezoelectric, piezomagnetic constructive equation, the steady-state solutions of variables such as stress, strain, displacement, electric displacement, electric field intensity, electric potential, magnetic intensity, magnetic potential under additional stimulations are deduced, thereof it can provide good theoretical basement for the dynamic control of the piezoelectric, piezomagnetic materials in the space spherical symmetry.
Investigation of the Spherical Stellarator Concept - Final Report
Energy Technology Data Exchange (ETDEWEB)
Moroz, P.E.
2000-10-15
This document is a final report of the U.S. DOE grant entitled ''Investigation of the Spherical Stellarator Concept'' which supported theoretical and numerical investigation of a novel fusion concept, the ultra-low-aspect-ratio stellarator system called Spherical Stellarator (SS). The research was concentrated on (a) search for principally different types of SS configurations, (b) optimization of SS configurations by varying the parameters of the coil systems, (c) finite beta and finite plasma current (including bootstrap current) equilibria in the SS, and (d) Monte Carlo particle transport simulations for the SS.
Spherically symmetric black-hole entropy without brick walls
Ren, Zhao; Yue-Qin, Wu; Li-Chun, Zhang
2003-11-01
Properties of the thermal radiation of black holes are discussed using a new equation of state density motivated by the generalized uncertainty relation in quantum gravity. There is no burst at the last stage of emission from a spherically symmetric black hole. When the new equation of state density is used to investigate the entropy of a bosonic field and fermionic field outside the horizon of a static spherically symmetric black hole, the divergence that appears in the brick-wall model is removed without any cutoff. The entropy proportional to the horizon area is derived from the contribution from the vicinity of the horizon.
Transitions in a magnetized quasi-laminar spherical Couette Flow
Kaprzyk, C; Seilmayer, M; Stefani, F
2016-01-01
First results of a new spherical Couette experiment are presented. The liquid metal flow in a spherical shell is exposed to a homogeneous axial magnetic field. For a Reynolds number Re=1000, we study the effect of increasing Hartmann number Ha. The resulting flow structures are inspected by ultrasound Doppler velocimetry. With a weak applied magnetic field, we observe an equatorially anti-symmetric jet instability with azimuthal wave number m=3. As the magnetic field strength increases, this instability vanishes. When the field is increased further, an equatorially symmetric return flow instability arises. Our observations are shown to be in good agreement with linear stability analysis and non-linear flow simulations.
Binary hard-sphere mixtures within spherical pores
Kim, S C; Lee, C H
1999-01-01
The free-energy model, which is based on the fundamental geometric measures of the particles, has been employed to investigate the structural properties of nonuniform hard-sphere mixtures within spherical pores. Monte Carlo simulation has been performed to calculate the density profiles of hard-sphere mixtures confined in spherical pores, and the simulation has been compared with the calculated results. Comparisons between the theoretical results and the simulation data have shown that the free-energy model demonstrates reliable accuracy and reproduces the simulation data accurately even for larger size ratios of hard spheres.
Accretion processes for general spherically symmetric compact objects
Energy Technology Data Exchange (ETDEWEB)
Bahamonde, Sebastian [University College London, Department of Mathematics, London (United Kingdom); Jamil, Mubasher [National University of Sciences and Technology (NUST), H-12, Department of Mathematics, School of Natural Sciences (SNS), Islamabad (Pakistan)
2015-10-15
We investigate the accretion process for different spherically symmetric space-time geometries for a static fluid. We analyze this procedure using the most general black hole metric ansatz. After that, we examine the accretion process for specific spherically symmetric metrics obtaining the velocity of the sound during the process and the critical speed of the flow of the fluid around the black hole. In addition, we study the behavior of the rate of change of the mass for each chosen metric for a barotropic fluid. (orig.)
A Spherical Earth Solution for TOA Lightning Location Retrieval
Koshak, W. J.; Solakiewicz, R. J.
1999-01-01
The problem of retrieving ligntning, ground-strike location on a spherical Earth surface using a network of 4 or more time-of-arrival (TOA) sensors is considered, It is shown that this problem has an analytic solution and therefore does not require the use of nonlinear estimation theory (e.g., minimization). The mathematical robustness of the analytic solution is tested using computer-generated lightning sources and simulated TOA measurement errors. A summary of a quasi-analytic extension of the spherical Earth solution to an oblate spheroid Earth geometry is also provided.
MECHANISM DESIGN AND MOTION ANALYSIS OF A SPHERICAL MOBILE ROBOT
Institute of Scientific and Technical Information of China (English)
Zhan Qiang; Jia Chuan; Ma Xiaohui; Zhai Yutao
2005-01-01
A new spherical mobile robot BHQ-1 is designed. The spherical robot is driven by two internally mounted motors that induce the ball to move straight and turn around on a flat surface. A dynamic model of the robot is developed with Lagrange method and factors affecting the driving torque of two motors are analyzed. The relationship between the turning radius of the robot and the length of two links is discussed in order to optimize its mechanism design. Simulation and experimental results demonstrate the good controllability and motion performance of BHQ-1.
Accretion Processes for General Spherically Symmetric Compact Objects
Bahamonde, Sebastian
2015-01-01
We investigate the accretion process for different spherically symmetric space-time geometries for a static fluid. We analyse this procedure using the most general black hole metric ansatz. After that, we examine the accretion process for specific spherically symmetric metrics obtaining the velocity of the sound during the process and the critical speed of the flow of the fluid around the black hole. In addition, we study the behaviour of the rate of change of the mass for each chosen metric for a barotropic fluid.
Institute of Scientific and Technical Information of China (English)
BI Chuanxing; CHEN Xinzhao; ZHOU Rong; CHEN Jian
2005-01-01
In the light of the concept of spherical wave source, the theoretical model of nearfield acoustic holography (NAH) based on the spherical wave superposition method (SWSM), including reconstruction of expansion coefficients, prediction of acoustic field, error sensitivity analysis, regularization method and a searching method with dual measurement surfaces for determining the optimal number of expansion terms, is established. Subsequently, the spherical wave source boundary point method (SWSBPM) and its application in the NAH are introduced briefly. Considering the similarity of the SWSM and the SWSBPM for realizing the NAH, they are compared. The similarities and differences of the two methods are illuminated by a rigorous mathematical justification and two experiments on a single source and two coherent sources in the semi-free acoustic field. And, the superiority of the NAH based on the SWSBPM is demonstrated.
Naked Singularities in Spherically Symmetric, Self-Similar Spacetimes
Wagh, S M; Wagh, Sanjay M.; Govinder, Keshlan S.
2001-01-01
We show that all known naked singularities in spherically symmetric self-similar spacetimes arise as a result of singular initial matter distribution. This is a result of the peculiarity of the coordinate transformation that takes these spacetimes into a separable form. Therefore, these examples of naked singularities are of no apparent consequence to astrophysical observations or theories.
Evolution of spherical overdensities in new agegraphic dark energy model
Setare, M R; Darabi, F
2016-01-01
We study the structure formation by investigating the spherical collapse model in the context of new agegraphic dark energy model in flat FRW cosmology. We compute the perturbational quantities $g(a)$, $\\delta_{c}(z_{c})$, $\\lambda(z_{c})$, $\\xi(z_{c})$, $\\Delta_{vir}(z_{c})$, $\\log[\
Analytical calculation of the wake potential of a spherical resonator
Directory of Open Access Journals (Sweden)
Sebastian Ratschow
2002-05-01
Full Text Available An analytical formula for the wake potential of a closed spherical resonator with perfectly conducting walls is presented. Mode analysis is used for the calculation. For every rotationally symmetric TM mode the loss parameter is calculated and the formula for the determination of the corresponding frequency is given. The final wake potential is an infinite sum over all modes mentioned above.
Design and Transmission Analysis of an Asymmetrical Spherical Parallel Manipulator
DEFF Research Database (Denmark)
Wu, Guanglei; Caro, Stéphane; Wang, Jiawei
2015-01-01
This paper presents an asymmetrical spherical parallel manipulator and its transmissibility analysis. This manipulator contains a center shaft to both generate a decoupled unlimited-torsion motion and support the mobile platform for high positioning accuracy. This work addresses the transmission ...
Time integration of the shallow water equations in spherical geometry
D. Lanser; J.G. Blom (Joke); J.G. Verwer (Jan)
2000-01-01
textabstractThe shallow water equations in spherical geometry provide a prototype for developing and testing numerical algorithms for atmospheric circulation models. In a previous paper we have studied a spatial discretization of these equations based on an Osher-type finite-volume method on stereog
Buckling-driven Delamination in Layered Spherical Shells
DEFF Research Database (Denmark)
Sørensen, Kim Dalsten; Jensen, Henrik Myhre
2008-01-01
An analysis of buckling-driven delamination of a thin film on a spherical substrate has been carried out. The effects of the substrate having a double curvature compared to previous studies of delamination on cylindrical substrates turn out to be non-trivial: In addition to the effect of the shap...
Wideband scalable probe for Spherical Near-Field Antenna measurements
DEFF Research Database (Denmark)
Kim, Oleksiy S.; Pivnenko, Sergey; Breinbjerg, Olav
2011-01-01
The paper presents a design of an open-boundary quad-ridged horn to be used as a wideband scalable dual-linearly polarized probe for spherical near-field antenna measurements. With a new higher-order probe correction technique developed at the Technical University of Denmark, the probe will enabl...
Multiphase, non-spherical gas accretion onto a black hole
Barai, Paramita; Nagamine, Kentaro
2011-01-01
(Abridged) We investigate non-spherical behavior of gas accreting onto a central supermassive black hole performing simulations using the SPH code GADGET-3 including radiative cooling and heating by the central X-ray source. As found in earlier 1D studies, our 3D simulations show that the accretion mode depends on the X-ray luminosity (L_X) for a fixed density at infinity and accretion efficiency. In the low L_X limit, gas accretes in a stable, spherically symmetric fashion. In the high L_X limit, the inner gas is significantly heated up and expands, reducing the central mass inflow rate. The expanding gas can turn into a strong enough outflow capable of expelling most of the gas at larger radii. For some intermediate L_X, the accretion flow becomes unstable developing prominent non-spherical features, the key reason for which is thermal instability (TI) as shown by our analyses. Small perturbations of the initially spherically symmetric accretion flow that is heated by the intermediate L_X quickly grow to fo...
Composite spherically symmetric configurations in Jordan-Brans-Dicke theory
Kozyrev, S
2010-01-01
In this article, a study of the scalar field shells in relativistic spherically symmetric configurations has been performed. We construct the composite solution of Jordan-Brans-Dicke field equation by matching the conformal Brans solutions at each junction surfaces. This approach allows us to associate rigorously with all solutions as a single glued "space", which is a unique differentiable manifold M^4.
The volume of fluid method in spherical coordinates
Janse, A.M.C.; Dijk, P.E.; Kuipers, J.A.M.
2000-01-01
The volume of fluid (VOF) method is a numerical technique to track the developing free surfaces of liquids in motion. This method can, for example, be applied to compute the liquid flow patterns in a rotating cone reactor. For this application a spherical coordinate system is most suited. The novel
Kinematic modeling, analysis and test on a quiet spherical pump
Guan, Dong; Wu, Jiu Hui; Jing, Li; Hilton, Harry H.; Lu, Kuan
2016-11-01
In this paper, design and modeling of a novel spherical pump are undertaken. Both sound and vibration properties of the pump are studied experimentally. The working mechanism of the pump is analyzed firstly, and then structural design and kinematic theory are modeled by using two different coordinate systems. Nonlinear kinematic constraint equations are developed using a generalized computational method for spatial kinematic analysis. These equations are solved to yield the displacement, angular velocity and acceleration properties of motion parts with different structural parameters. Sound and vibration characteristics of the spherical pump and traditional solenoid pumps are studied experimentally at different rotating speeds of 1000, 1500, 2000, 2500 and 3000 rev/min. Results indicate that sound pressure levels of the proposed spherical are reduced to 40.7 dB(A), which are 11.1 dB(A) lower than the traditional solenoid pump's 51.8 dB(A) at the rated operating conditions. The sound spectra are analyzed in detail in order to investigate the causes, which are structural pattern and working mechanisms. The proposed spherical pump has many advantages and can be utilized as a substitute for other pumps in some special fields, such as hospital facilities and household appliances.
ON APPROXIMATION BY SPHERICAL REPRODUCING KERNEL HILBERT SPACES
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The spherical approximation between two nested reproducing kernels Hilbert spaces generated from different smooth kernels is investigated. It is shown that the functions of a space can be approximated by that of the subspace with better smoothness. Furthermore, the upper bound of approximation error is given.
Particle Velocity Measurement for Spherical Wave in Solid
Institute of Scientific and Technical Information of China (English)
ZHENG Xue-feng; WANG Zhan-jiang; LIN Jun-de; SHEN Jun-yi
2006-01-01
An experimental technique for research on spherical divergent wave propagation in a solid has been developed,in which the source of generating spherical wave is a center initiating explosive charge designed in a mini-spherical shape with yield equivalent to 0.125 g and 0. 486 g TNT and a set of circular electromagnetic particle velocity gages is used to record the particle velocity histories. By using the circular electromagnetic particle velocity gages, the signal outputs not only are unattenuated due to the geometrical divergence, but also represent the average of the measured dynamic states of the medium over a circle on the wavefront. The distinctive features of this technique are very useful for the study of spherical divergent wave propagation in a solid, especially in an inhomogeneous solid, and the corresponding material dynamics.Many experimental measurements were conducted in polymethylmethacrylate (PMMA) and granite by means of the technique, and the reproducibility of tests was shown to be good. The measurement technique of the circular electromagnetic particle velocity gages is also suitable to the case of cylindrical wave.
Spacelike spherically symmetric CMC foliation in the extended Schwarzschild spacetime
Lee, Kuo-Wei
2015-01-01
We first summarize the characterization of smooth spacelike spherically symmetric constant mean curvature (SS-CMC) hypersurfaces in the Schwarzschild spacetime and Kruskal extension. Then use the characterization to prove special SS-CMC foliation property, and verify part of the conjecture by Malec and \\'{O} Murchadha in their 2003 paper.
A note on spherical derivatives and normal families
Grahl, Jürgen
2010-01-01
We show that a family of meromorphic functions in the unit disk $\\dk$ whose spherical derivatives are uniformly bounded away from zero is normal. Furthermore, we show that for each $f$ meromorphic in $\\dk$ we have $\\inf_{z\\in\\dk} f^#(z)\\le \\frac{1}{2}
Dynamics of Shape Fluctuations of Quasi-spherical Vesicles Revisited
DEFF Research Database (Denmark)
Miao, L.; Lomholt, Michael Andersen; Kleis, J.
2002-01-01
In this paper, the dynamics of spontaneous shape fluctuations of a single, giant quasi-spherical vesicle formed from a single lipid species is revisited theoretically. A coherent physical theory for the dynamics is developed based on a number of fundamental principles and considerations, and a sy...
Precise Measurement of Separation Between Two Spherical Source Masses
Institute of Scientific and Technical Information of China (English)
陈德才; 罗俊; 胡忠坤; 赵亮
2004-01-01
A driving gauge method is performed to determine the separation between two spherical source masses in the measurement of Newtonian gravitational constant G. The experimental result shows that the uncertainty of determining the separation is about 0.35μm, which would contribute an uncertainty of 7.3ppm to the value of G.
Observers in spacetimes with spherical and axial symmetries
Gusin, Pawel; Kusnierz, Bartosz; Radosz, Andrzej
2015-01-01
We introduce in the explicit form the tetrads of arbitrary observers in spacetimes with spherical and axial symmetries. The observers confined to the equatorial plane are parametrized by the pair of functions. We apply this description in the analysis of the null-geodesics in the observers' frames. The observers with the constant acceleration are distinguished.
3D Face Compression and Recognition using Spherical Wavelet Parametrization
Directory of Open Access Journals (Sweden)
Rabab M. Ramadan
2012-09-01
Full Text Available In this research an innovative fully automated 3D face compression and recognition system is presented. Several novelties are introduced to make the system performance robust and efficient. These novelties include: First, an automatic pose correction and normalization process by using curvature analysis for nose tip detection and iterative closest point (ICP image registration. Second, the use of spherical based wavelet coefficients for efficient representation of the 3D face. The spherical wavelet transformation is used to decompose the face image into multi-resolution sub images characterizing the underlying functions in a local fashion in both spacial and frequency domains. Two representation features based on spherical wavelet parameterization of the face image were proposed for the 3D face compression and recognition. Principle component analysis (PCA is used to project to a low resolution sub-band. To evaluate the performance of the proposed approach, experiments were performed on the GAVAB face database. Experimental results show that the spherical wavelet coefficients yield excellent compression capabilities with minimal set of features. Haar wavelet coefficients extracted from the face geometry image was found to generate good recognition results that outperform other methods working on the GAVAB database.
Is the dark halo of our Galaxy spherical?
Helmi, A
2004-01-01
It has been recently claimed that the confined structure of the debris from the Sagittarius dwarf implies that the dark matter halo of our Galaxy should be nearly spherical, in strong contrast with predictions from cold dark matter simulations, where dark haloes are found to have typical density axi
Time integration of the shallow water equations in spherical geometry
Lanser, D.; Blom, J.G.; Verwer, J.G.
2000-01-01
The shallow water equations in spherical geometry provide a prototype for developing and testing numerical algorithms for atmospheric circulation models. In a previous paper we have studied a spatial discretization of these equations based on an Osher-type finite-volume method on stereographic and l
Dynamics and control of vibratory gyroscopes with special spherical symmetry
CSIR Research Space (South Africa)
Shatalov, M
2006-01-01
Full Text Available system and determination of the scale factors. In the present paper the effect of vibrating pattern precession is considered in a spherical coordinates. On the basis of exact solution of 3-D equations of motion of thick isotropic sphere, which...
Wavemoth-Fast Spherical Harmonic Transforms by Butterfly Matrix Compression
Seljebotn, D. S.
2012-03-01
We present Wavemoth, an experimental open source code for computing scalar spherical harmonic transforms (SHTs). Such transforms are ubiquitous in astronomical data analysis. Our code performs substantially better than existing publicly available codes owing to improvements on two fronts. First, the computational core is made more efficient by using small amounts of pre-computed data, as well as paying attention to CPU instruction pipelining and cache usage. Second, Wavemoth makes use of a fast and numerically stable algorithm based on compressing a set of linear operators in a pre-computation step. The resulting SHT scales as O(L 2log2 L) for the resolution range of practical interest, where L denotes the spherical harmonic truncation degree. For low- and medium-range resolutions, Wavemoth tends to be twice as fast as libpsht, which is the current state-of-the-art implementation for the HEALPix grid. At the resolution of the Planck experiment, L ~ 4000, Wavemoth is between three and six times faster than libpsht, depending on the computer architecture and the required precision. Because of the experimental nature of the project, only spherical harmonic synthesis is currently supported, although adding support for spherical harmonic analysis should be trivial.
Simple compactifications and polar decomposition of homogeneous real spherical spaces
DEFF Research Database (Denmark)
Knop, Friedrich; Krötz, Bernhard; Sayag, Eitan
2015-01-01
Let Z be an algebraic homogeneous space Z = G/H attached to real reductive Lie group G. We assume that Z is real spherical, i.e., minimal parabolic subgroups have open orbits on Z. For such spaces, we investigate their large scale geometry and provide a polar decomposition. This is obtained from...
Packing of non-spherical aggregate particles by DEM
Stroeven, P.; He, H.
2013-01-01
Loose random and dense random mono-size pacl
Novel spherical hohlraum with cylindrical laser entrance holes and shields
Energy Technology Data Exchange (ETDEWEB)
Lan, Ke [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Center for Applied Physics and Technology, Peking University, Beijing 100871 (China); Zheng, Wudi [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)
2014-09-15
Our recent works [K. Lan et al., Phys. Plasmas 21, 010704 (2014); K. Lan et al., Phys. Plasmas 21, 052704 (2014)] have shown that the octahedral spherical hohlraums are superior to the cylindrical hohlraums in both higher symmetry during the capsule implosion and lower backscatter without supplementary technology. However, both the coupling efficiency from the drive laser energy to the capsule and the capsule symmetry decrease remarkably when larger laser entrance holes (LEHs) are used. In addition, the laser beams injected at angles > 45° transport close to the hohlraum wall, thus the wall blowoff causes the LEH to close faster and results in strong laser plasma interactions inside the spherical hohlraums. In this letter, we propose a novel octahedral hohlraum with LEH shields and cylindrical LEHs to alleviate these problems. From our theoretical study, with the LEH shields, the laser coupling efficiency is significantly increased and the capsule symmetry is remarkably improved in the spherical hohlraums. The cylindrical LEHs take advantage of the cylindrical hohlraum near the LEH and mitigate the influence of the blowoff on laser transport inside a spherical hohlraum. The cylindrical LEHs can also be applied to the rugby and elliptical hohlraums.
Internally Pressurized Spherical and Cylindrical Cavities in Rock Salt
DEFF Research Database (Denmark)
Krenk, Steen
1978-01-01
The paper deals with the stress distribution around cavities under pressure in an infinite, non-linear elastic material. A homogeneous stress state is assumed at infinity. For spherical and cylindrical cavities simple formulae are derived for the stress concentration, the extent of the non-linear...
Investigation of spherical aberration effects on coherent lidar performance
DEFF Research Database (Denmark)
Hu, Qi; Rodrigo, Peter John; Iversen, Theis Faber Quist
2013-01-01
In this paper we demonstrate experimentally the performance of a monostatic coherent lidar system under the influence of phase aberrations, especially the typically predominant spherical aberration (SA). The performance is evaluated by probing the spatial weighting function of the lidar system...
Spherical agglomerates of lactose with enhanced mechanical properties.
Lamešić, Dejan; Planinšek, Odon; Lavrič, Zoran; Ilić, Ilija
2017-01-10
The aim of this study was to prepare spherical agglomerates of lactose and to evaluate their physicochemical properties, flow properties, particle friability and compaction properties, and to compare them to commercially available types of lactose for direct compression (spray-dried, granulated and anhydrous β-lactose). Porous spherical agglomerates of α-lactose monohydrate with radially arranged prism-like primary particles were prepared exhibiting a high specific surface area. All types of lactose analysed had passable or better flow properties, except for anhydrous β-lactose, which had poor flowability. Particle friability was more pronounced in larger granulated lactose particles; however, particle structure was retained in all samples analysed. The mechanical properties of spherical agglomerates of lactose, in terms of compressibility, established with Walker analysis, and compactibility, established with a compactibility profile, were found to be superior to any commercially available types of lactose. Higher compactibility of spherical agglomerates of lactose is ascribed to significantly higher particle surface area due to a unique internal structure with higher susceptibility to fragmentation. Copyright © 2016 Elsevier B.V. All rights reserved.
Aerosol-Assisted Self-Assembly of Mesostructured Spherical Nanoparticles
Energy Technology Data Exchange (ETDEWEB)
Brinker, C.J.; Fan,; H.; Lu, Y.; Rieker, T.; Stump, A.; Ward, T.L.
1999-03-23
Nanostructured particles exhibiting well-defined pore sizes and pore connectivities (1-, 2-, or 3-dimensional) are of interest for catalysis, chromatography, controlled release, low dielectric constant fillers, and custom-designed pigments and optical hosts. During the last several years considerable progress has been made on controlling the macroscopic forms of mesoporous silicas prepared by surfactant and block copolymer liquid crystalline templating procedures. Typically interfacial phenomena are used to control the macroscopic form (particles, fibers, or films), while self-assembly of amphiphilic surfactants or polymers is used to control the mesostructure. To date, although a variety of spherical or nearly-spherical particles have been prepared, their extent of order is limited as is the range of attainable mesostructures. They report a rapid, aerosol process that results in solid, completely ordered spherical particles with stable hexagonal, cubic, or vesicular mesostructures. The process relies on evaporation-induced interfacial self-assembly (EISA) confined to a spherical aerosol droplet. The process is simple and generalizable to a variety of materials combinations. Additionally, it can be modified to provide the first aerosol route to the formation of ordered mesostructured films.
Minimum Q Electrically Small Spherical Magnetic Dipole Antenna - Theory
DEFF Research Database (Denmark)
Breinbjerg, Olav; Kim, Oleksiy S.
2009-01-01
The stored energies, radiated power, and quality factor of a magnetic-dipole antenna, consisting of a spherical electrical surface current density enclosing a magnetic core, is obtained through direct spatial integration of the internally and externally radiated field expressed in terms of spheri...
Demagnetization factor for a powder of randomly packed spherical particles
DEFF Research Database (Denmark)
Bjørk, Rasmus; Bahl, Christian R.H.
2013-01-01
The demagnetization factors for randomly packed spherical particle powders with different porosities, sample aspect ratios, and monodisperse, normal, and log-normal particle size distributions have been calculated using a numerical model. For a relative permeability of 2, comparable to room...... permeability. © 2013 AIP Publishing LLC...
Axially and spherically symmetric solitons in warm plasma
Dvornikov, Maxim
2010-01-01
We study the existence of stable axially and spherically symmetric plasma structures on the basis of the new nonlinear Schrodinger equation (NLSE) accounting for nonlocal electron nonlinearities. The numerical solutions of NLSE having the form of spatial solitions are obtained and their stability is analyzed. We discuss the possible application of the obtained results to the theoretical description of natural plasmoids in the atmosphere.
Advanced spherical near-field antenna measurement techniques
DEFF Research Database (Denmark)
Nielsen, Jeppe Majlund; Pivnenko, Sergey; Breinbjerg, Olav
2011-01-01
The DTU-ESA facility has since the 1980es provided highly accurate antenna radiation pattern measurements and gain calibration by use of the probe corrected spherical nearfield technique, both for ESA (the European Space Agency) and other customers and continues to do so. Recent years activities ...
Testing for Sphericity in Phase I Control Chart Applications
DEFF Research Database (Denmark)
Windfeldt, Gitte Bjørg; Bisgaard, Søren
2009-01-01
When using (x) over bar -R charts it is a crucial assumption that the observations within samples are independent and have common variance. However, this assumption is almost never checked. We propose to use the samples gathered during the phase I study and the test for distributional sphericity...
Heterogeneous nucleation on potent spherical substrates during solidification
Energy Technology Data Exchange (ETDEWEB)
Ma Qian [BCAST - Brunel Centre for Advanced Solidification Technology, Brunel University, West London UB8 3PH (United Kingdom)]. E-mail: ma.qian@brunel.ac.uk
2007-02-15
For a spherical-cap nucleus to become a 'transformation nucleus', the linear dimension (d) of the flat substrate must exceed the critical nucleus size (2r *). This Turnbull criterion (d {>=} 2r *) defines a minimum undercooling for grain formation on, and effective inoculation with, flat nucleating substrates. However, for nucleation on potent substrates the spherical-cap model is no longer tenable. The free growth model has in general considered the growth of a two-dimensional nucleus on a potent flat substrate. Inspired by the particle-core structures observed in magnesium alloys after inoculation with nearly spherical zirconium particles, a model has been proposed, on the basis of an adsorption and surface diffusion mechanism, for heterogeneous nucleation and grain formation on potent spherical substrates of d {>=} 2r *. The critical undercooling required is found to be approximately the same as that defined by Turnbull's patch nucleation theory. The model shows excellent agreement with experiments compared from different perspectives.
Acoustic source localization in mixed field using spherical microphone arrays
Huang, Qinghua; Wang, Tong
2014-12-01
Spherical microphone arrays have been used for source localization in three-dimensional space recently. In this paper, a two-stage algorithm is developed to localize mixed far-field and near-field acoustic sources in free-field environment. In the first stage, an array signal model is constructed in the spherical harmonics domain. The recurrent relation of spherical harmonics is independent of far-field and near-field mode strengths. Therefore, it is used to develop spherical estimating signal parameter via rotational invariance technique (ESPRIT)-like approach to estimate directions of arrival (DOAs) for both far-field and near-field sources. In the second stage, based on the estimated DOAs, simple one-dimensional MUSIC spectrum is exploited to distinguish far-field and near-field sources and estimate the ranges of near-field sources. The proposed algorithm can avoid multidimensional search and parameter pairing. Simulation results demonstrate the good performance for localizing far-field sources, or near-field ones, or mixed field sources.
Sufficient condition for Blackhole formation in spherical gravitational collapse
Giambo, R; Magli, G; Giambo', Roberto; Giannoni, Fabio; Magli, Giulio
2002-01-01
A sufficient condition for the validity of Cosmic Censorship in spherical gravitational collapse is formulated and proved. The condition relies on an attractive mathematical property of the apparent horizon, which holds if ''minimal'' requirements of physical reasonableness are satisfied by the matter model.
DLVO interaction energies between hollow spherical particles and collector surfaces
The surface element integration technique was used to systematically study Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energies/forces between hollow spherical particles (HPs) and a planar surface or two intercepting half planes under different ionic strength conditions. The inner and outer ...
Thermal undulations of quasi-spherical vesicles stabilized by gravity
DEFF Research Database (Denmark)
Henriksen, Jonas Rosager; Ipsen, John Hjorth
2002-01-01
The classical treatment of quasi-spherical vesicle undulations has, in the present work, been reviewed and extended to systems, which are affected by a gravitational field caused by a density difference across the membrane. The effects have been studied by the use of perturbation theory leading...
Calculation of Eddy currents in the ETE spherical torus
Energy Technology Data Exchange (ETDEWEB)
Ludwig, Gerson Otto
2002-07-01
A circuit model based on a Green's function method was developed to evaluate the currents induced during startup in the vessel of ETE (Spherical Tokamak Experiment). The eddy currents distribution is calculated using a thin shell approximation for the vacuum vessel and local curvilinear coordinates. The results are compared with values of the eddy currents measured in ETE. (author)
Spherical nanoindentation stress-strain analysis, Version 1
Energy Technology Data Exchange (ETDEWEB)
2016-11-07
Nanoindentation is a tool that allows the mechanical response of a variety of materials at the nano to micron length scale to be measured. Recent advances in spherical nanoindentation techniques have allowed for a more reliable and meaningful characterization of the mechanical response from nanoindentation experiments in the form on an indentation stress-strain curve. This code base, Spin, is written in MATLAB (The Mathworks, Inc.) and based on the analysis protocols developed by S.R. Kalidindi and S. Pathak [1, 2]. The inputs include the displacement, load, harmonic contact stiffness, harmonic displacement, and harmonic load from spherical nanoindentation tests in the form of an Excel (Microsoft) spreadsheet. The outputs include indentation stress-strain curves and indentation properties as well their variance due to the uncertainty of the zero-point correction in the form of MATLAB data (.mat) and figures (.png). [1] S. Pathak, S.R. Kalidindi. Spherical nanoindentation stress–strain curves, Mater. Sci. Eng R-Rep 91 (2015). [2] S.R. Kalidindi, S. Pathak. Determination of the effective zero-point and the extraction of spherical nanoindentation stress-strain curves, Acta Materialia 56 (2008) 3523-3532.
Novel Spherical Robot with Hybrid Pendulum Driving Mechanism
Directory of Open Access Journals (Sweden)
Sung-Su Ahn
2014-11-01
Full Text Available As regards omnidirectional driving, conventional one- and two-pendulum spherical robots have a limited capability due to a limited pendulum motion range. In particular, such robots cannot move from a stationary state in a parallel direction to the center horizontal axis to which the pendulums are attached. Thus, to overcome the limited driving capability of one- and two-pendulum driven spherical robots, a passive version of a spherical robot, called KisBot II, was developed with a curved two-pendulum driving mechanism operated by a joystick. However, this paper presents an active upgraded version of KisBot II that includes a DSP-based control system and Task-based software architecture for driving control and data communication, respectively. A dynamic model for two-pendulum driving is derived using the Lagrange equation method, and a feedback controller for linear driving using two pendulums is then constructed based on the dynamic model. Experiments with several motions verify the driving efficiency of the proposed novel spherical robot.
Resonance and Neck Length for a Spherical Resonator
Directory of Open Access Journals (Sweden)
Emily Corning
2011-06-01
Full Text Available The relationship between the neck length of a spherical resonator and its period of fundamental resonance was investigated. This was done by measuring the frequency of fundamental resonance of the resonator at 6 different neck lengths. It was found that its resonance resembled Helmholtz resonance but was not that of ideal Helmholtz resonance.
Variable Free Spectral Range Spherical Mirror Fabry-Perot Interferometer
Kerner, K; Yashchuk, V V; Budker, D; Kerner, Katherine; Rochester, Simon M.; Yashchuk, Valeriy V.
2003-01-01
A spherical Fabry-Perot interferometer with adjustable mirror spacing is used to produce interference fringes with frequency separation (c/2L)/N, N=2-15. The conditions for observation of these fringes are derived from the consideration of the eigenmodes of the cavity with high transverse indices.
Radiation quality factor of spherical antennas with material cores
DEFF Research Database (Denmark)
Hansen, Troels Vejle; Kim, Oleksiy S.; Breinbjerg, Olav
2011-01-01
This paper gives a description of the radiation quality factor and resonances of spherical antennas with material cores. Conditions for cavity and radiating resonances are given, and a theoretical description of the radiation quality factor, as well as simple expressions describing the relative...
STRESS CONCENTRATION DUE TO A SPHERICAL VOID UNDER HERTZIAN CONTACT
Directory of Open Access Journals (Sweden)
Stelian ALACI,
2010-06-01
Full Text Available The present paper presents the method of estimating the stress concentrator effect of a spherical void from an elastic half-space. An essential part consists in estimation of FEM error by finding the contact pressure from half-plane using an analytical method. Next, the stress concentrator effect of the same void, except for placed into elastic space, is found.
Minimum Q circularly polarized electrically small spherical antennas
DEFF Research Database (Denmark)
Kim, Oleksiy S.
2011-01-01
The radiation problem for the TM10- and TE10-mode electric current densities on the surface of a spherical magnetic-coated PEC core is solved analytically. The combination of the electric and magnetic dipole modes reduces the radiation Q of the antenna. Moreover, with an appropriately designed ma...... spherical helix antenna with a magnetic-coated PEC core radiating both TM10 and TE10 spherical modes exhibits a perfect circular polarization in almost all directions. The antenna is self-resonant with the radiation Q being 0.67QChu, or 1.27Qdual.......The radiation problem for the TM10- and TE10-mode electric current densities on the surface of a spherical magnetic-coated PEC core is solved analytically. The combination of the electric and magnetic dipole modes reduces the radiation Q of the antenna. Moreover, with an appropriately designed...... magnetic-coated PEC core the stored energies of these modes balance each other making the antenna self-resonant and at the same time ensuring a perfect circularly polarized radiation. Numerical results for a practical dual-mode electrically small antenna confirm the theoretical predictions. A 4-arm...
MODELING RESULTS FROM CESIUM ION EXCHANGE PROCESSING WITH SPHERICAL RESINS
Energy Technology Data Exchange (ETDEWEB)
Nash, C.; Hang, T.; Aleman, S.
2011-01-03
Ion exchange modeling was conducted at the Savannah River National Laboratory to compare the performance of two organic resins in support of Small Column Ion Exchange (SCIX). In-tank ion exchange (IX) columns are being considered for cesium removal at Hanford and the Savannah River Site (SRS). The spherical forms of resorcinol formaldehyde ion exchange resin (sRF) as well as a hypothetical spherical SuperLig{reg_sign} 644 (SL644) are evaluated for decontamination of dissolved saltcake wastes (supernates). Both SuperLig{reg_sign} and resorcinol formaldehyde resin beds can exhibit hydraulic problems in their granular (nonspherical) forms. SRS waste is generally lower in potassium and organic components than Hanford waste. Using VERSE-LC Version 7.8 along with the cesium Freundlich/Langmuir isotherms to simulate the waste decontamination in ion exchange columns, spherical SL644 was found to reduce column cycling by 50% for high-potassium supernates, but sRF performed equally well for the lowest-potassium feeds. Reduced cycling results in reduction of nitric acid (resin elution) and sodium addition (resin regeneration), therefore, significantly reducing life-cycle operational costs. These findings motivate the development of a spherical form of SL644. This work demonstrates the versatility of the ion exchange modeling to study the effects of resin characteristics on processing cycles, rates, and cold chemical consumption. The value of a resin with increased selectivity for cesium over potassium can be assessed for further development.
Spherically symmetric inhomogeneous bianisotropic media: Wave propagation and light scattering
DEFF Research Database (Denmark)
Novitsky, Andrey; Shalin, Alexander S.; Lavrinenko, Andrei
2017-01-01
We develop a technique for finding closed-form expressions for electromagnetic fields in radially inhomogeneous bianisotropic media, both the solutions of the Maxwell equations and material tensors being defined by the set of auxiliary two-dimensional matrices. The approach is applied to determine...... the scattering cross-sections by spherical particles, the fields inside which correspond to the Airy-exponential waves....
Exact solution of the neutron transport equation in spherical geometry
Energy Technology Data Exchange (ETDEWEB)
Anli, Fikret; Akkurt, Abdullah; Yildirim, Hueseyin; Ates, Kemal [Kahramanmaras Suetcue Imam Univ. (Turkey). Faculty of Sciences and Letters
2017-03-15
Solution of the neutron transport equation in one dimensional slab geometry construct a basis for the solution of neutron transport equation in a curvilinear geometry. Therefore, in this work, we attempt to derive an exact analytical benchmark solution for both neutron transport equations in slab and spherical medium by using P{sub N} approximation which is widely used in neutron transport theory.
Finite size melting of spherical solid-liquid aluminium interfaces
DEFF Research Database (Denmark)
Chang, J.; Johnson, Erik; Sakai, T.
2009-01-01
We have investigated the melting of nano-sized cone shaped aluminium needles coated with amorphous carbon using transmission electron microscopy. The interface between solid and liquid aluminium was found to have spherical topology. For needles with fixed apex angle, the depressed melting...
Reynolds stress and heat flux in spherical shell convection
Käpylä, P. J.; Mantere, M. J.; Guerrero, G.; Brandenburg, A.; Chatterjee, P.
2011-07-01
Context. Turbulent fluxes of angular momentum and enthalpy or heat due to rotationally affected convection play a key role in determining differential rotation of stars. Their dependence on latitude and depth has been determined in the past from convection simulations in Cartesian or spherical simulations. Here we perform a systematic comparison between the two geometries as a function of the rotation rate. Aims: Here we want to extend the earlier studies by using spherical wedges to obtain turbulent angular momentum and heat transport as functions of the rotation rate from stratified convection. We compare results from spherical and Cartesian models in the same parameter regime in order to study whether restricted geometry introduces artefacts into the results. In particular, we want to clarify whether the sharp equatorial profile of the horizontal Reynolds stress found in earlier Cartesian models is also reproduced in spherical geometry. Methods: We employ direct numerical simulations of turbulent convection in spherical and Cartesian geometries. In order to alleviate the computational cost in the spherical runs, and to reach as high spatial resolution as possible, we model only parts of the latitude and longitude. The rotational influence, measured by the Coriolis number or inverse Rossby number, is varied from zero to roughly seven, which is the regime that is likely to be realised in the solar convection zone. Cartesian simulations are performed in overlapping parameter regimes. Results: For slow rotation we find that the radial and latitudinal turbulent angular momentum fluxes are directed inward and equatorward, respectively. In the rapid rotation regime the radial flux changes sign in accordance with earlier numerical results, but in contradiction with theory. The latitudinal flux remains mostly equatorward and develops a maximum close to the equator. In Cartesian simulations this peak can be explained by the strong "banana cells". Their effect in the
Holographic Refraction and the Measurement of Spherical Ametropia.
Nguyen, Nicholas Hoai Nam
2016-10-01
To evaluate the performance of a holographic logMAR chart for the subjective spherical refraction of the human eye. Bland-Altman analysis was used to assess the level of agreement between subjective spherical refraction using the holographic logMAR chart and conventional autorefraction and subjective spherical refraction. The 95% limits of agreement (LoA) were calculated between holographic refraction and the two standard methods (subjective and autorefraction). Holographic refraction has a lower mean spherical refraction when compared to conventional refraction (LoA 0.11 ± 0.65 D) and when compared to autorefraction (LoA 0.36 ± 0.77 D). After correcting for systemic bias, this is comparable between autorefraction and conventional subjective refraction (LoA 0.45 ± 0.79 D). After correcting for differences in vergence distance and chromatic aberration between holographic and conventional refraction, approximately 65% (group 1) of measurements between holography and conventional subjective refraction were similar (MD = 0.13 D, SD = 0.00 D). The remaining 35% (group 2) had a mean difference of 0.45 D (SD = 0.12 D) between the two subjective methods. Descriptive statistics showed group 2's mean age (21 years, SD = 13 years) was considerably lower than group 1's mean age (41 years, SD = 17), suggesting accommodation may have a role in the greater mean difference of group 2. Overall, holographic refraction has good agreement with conventional refraction and is a viable alternative for spherical subjective refraction. A larger bias between holographic and conventional refraction was found in younger subjects than older subjects, suggesting an association between accommodation and myopic over-correction during holographic refraction.
Modeling of Ionospheric Delay for SBAS Using Spherical Harmonics Functions
Directory of Open Access Journals (Sweden)
Deokhwa Han
2013-06-01
Full Text Available In SBAS (satellite-based augmentation system, it is important to estimate ionospheric delay accurately to guarantee user's accuracy and integrity. Grid based ionospheric models are generally used to estimate ionospheric delay for SBAS. In grid based model, SBAS broadcasts vertical ionospheric delays at the grid point, and users get their ionospheric delay by interpolating those values. Ionospheric model based on spherical harmonics function is another method to estimate ionospheric delay. This is a function based approach and spherical harmonics function is a 2-D fourier series, containing the product of latitude dependent associated Legendre functions and the sum of the longitude dependent sine and cosine terms. Using ionospheric delay measurements, coefficients for each spherical harmonics functions are estimated. If these coefficients are known, user can reconstruct ionospheric delay. In this paper, we consider the spherical harmonics based model and propose a ionospheric delay estimation strategy for SBAS that can be used to mitigate ionospheric delay estimation error, especially in storm condition. First, coefficients are estimated under initial order and degree. Then residual errors for each measurement are modeled by higher order and degree terms, then coefficients for these terms are estimated. Because SBAS message capacity is limited, in normal condition, initial order terms are only used to estimate ionospheric delay. If ionospheric storm is detected and there is need to mitigate the error, higher order terms are also used and error can be decreased. To compare the accuracy of spherical harmonics based model with grid based model, some post-processing test results are presented. Raw observation data is obtained from RINEX format and the root mean square(RMS and max value of residual errors are presented.
Robustness of oscillatory α2 dynamos in spherical wedges
Cole, E.; Brandenburg, A.; Käpylä, P. J.; Käpylä, M. J.
2016-10-01
Context. Large-scale dynamo simulations are sometimes confined to spherical wedge geometries by imposing artificial boundary conditions at high latitudes. This may lead to spatio-temporal behaviours that are not representative of those in full spherical shells. Aims: We study the connection between spherical wedge and full spherical shell geometries using simple mean-field dynamos. Methods: We solve the equations for one-dimensional time-dependent α2 and α2Ω mean-field dynamos with only latitudinal extent to examine the effects of varying the polar angle θ0 between the latitudinal boundaries and the poles in spherical coordinates. Results: In the case of constant α and ηt profiles, we find oscillatory solutions only with the commonly used perfect conductor boundary condition in a wedge geometry, while for full spheres all boundary conditions produce stationary solutions, indicating that perfect conductor conditions lead to unphysical solutions in such a wedge setup. To search for configurations in which this problem can be alleviated we choose a profile of the turbulent magnetic diffusivity that decreases toward the poles, corresponding to high conductivity there. Oscillatory solutions are now achieved with models extending to the poles, but the magnetic field is strongly concentrated near the poles and the oscillation period is very long. By changing both the turbulent magnetic diffusivity and α profiles so that both effects are more concentrated toward the equator, we see oscillatory dynamos with equatorward drift, shorter cycles, and magnetic fields distributed over a wider range of latitudes. Those profiles thus remove the sensitive and unphysical dependence on θ0. When introducing radial shear, we again see oscillatory dynamos, and the direction of drift follows the Parker-Yoshimura rule. Conclusions: A reduced α effect near the poles with a turbulent diffusivity concentrated toward the equator yields oscillatory dynamos with equatorward migration and
DEFF Research Database (Denmark)
Jensen, Jesper Rindom; Christensen, Mads Græsbøll; Larsen, Morten Holm
2009-01-01
Recently, multiple description spherical trellis-coded quantization (MDSTCQ) for quantization of sinusoidal parameters was proposed, which suffered from a suboptimal implementation. Therefore, we propose the multiple description spherical quantization with repetition coding of the amplitudes (MDS...
A falling-head procedure for the measurement of filter media sphericity
African Journals Online (AJOL)
A falling-head procedure for the measurement of filter media sphericity. ... Filter media sphericity is normally determined experimentally in a laboratory filtration column. The pressure drop is measured across ... Article Metrics. Metrics Loading .
Mathematical models of grinding manufacture and tooth contact analysis of spherical gears
Institute of Scientific and Technical Information of China (English)
LI Ting; PAN CunYun
2009-01-01
act paths of the meshing of the spherical gear pair are complex and multiform.These are very useful to further investigations on transmission theory and practical applications of spherical gear pairs.
Supersymmetry and eigensurface topology of the spherical quantum pendulum
Schmidt, Burkhard
2014-01-01
We undertook a mutually complementary analytic and computational study of the full-fledged spherical (3D) quantum rotor subject to combined orienting and aligning interactions characterized, respectively, by dimensionless parameters $\\eta$ and $\\zeta$. By making use of supersymmetric quantum mechanics (SUSY QM), we found two sets of conditions under which the problem of a spherical quantum pendulum becomes analytically solvable. These conditions coincide with the loci $\\zeta=\\frac{\\eta^2}{4k^2}$ of the intersections of the eigenenergy surfaces spanned by the $\\eta$ and $\\zeta$ parameters. The integer topological index $k$ is independent of the eigenstate and thus of the projection quantum number $m$. These findings have repercussions for rotational spectra and dynamics of molecules subject to combined permanent and induced dipole interactions.
Turbulent dynamos in spherical shell segments of varying geometrical extent
Mitra, Dhrubaditya; Brandenburg, Axel; Moss, David
2008-01-01
We use three-dimensional direct numerical simulations of the helically forced magnetohydrodynamic equations in spherical shell segments in order to study the effects of changes in the geometrical shape and size of the domain on the growth and saturation of large-scale magnetic fields. We inject kinetic energy along with kinetic helicity in spherical domains via helical forcing using Chandrasekhar-Kendall functions. We use perfect conductor boundary conditions for the magnetic field to ensure that no magnetic helicity escapes the domain boundaries. We find dynamo action giving rise to magnetic fields at scales larger than the characteristic scale of the forcing. The magnetic energy exceeds the kinetic energy over dissipative time scales, similar to that seen earlier in Cartesian simulations in periodic boxes. As we increase the size of the domain in the azimuthal direction we find that the nonlinearly saturated magnetic field organizes itself in long-lived cellular structures with aspect ratios close to unity....
Asymptotic dynamics of a frustrated model with spherical constraint
Energy Technology Data Exchange (ETDEWEB)
Mendoza-Coto, Alejandro [Departamento de Física, Universidade Federal do Rio Grande do Sul, CP 15051, 91501-970 Porto Alegre (Brazil); Díaz-Méndez, Rogelio, E-mail: rogelio@fisica.uh.cu [Nanophysics Group, Electric Engineering Faculty, CUJAE, CP 19390, La Habana (Cuba); Group of Complex Systems, Physics Faculty, University of Havana, CP 10400, La Habana (Cuba)
2013-11-15
We solve the Langevin dynamics of a continuum model with a spherical constraint, considering a ferromagnetic exchange and a long-range antiferromagnetic interaction. Analytical results within the Hartree approximation show an equivalence in the form of spatial and auto-correlation functions in the long time regime between this model and the recently studied Ginzburg–Landau frustrated model. The low-temperature behavior is discussed in the context of glassy dynamics. The emergence of interesting features regarding the establishment of the saturated phase is also analyzed in the view of recent literature. - Highlights: • We solve the long-time dynamics of a model with ferro and antiferromagnetic interactions and spherical restriction. • We find the critical behavior of spatial and self-correlations. • The new results are analyzed in the frame of existing literature on glassy states and thin films.
Portable digital holographic microscope using spherical reference beam
Watanabe, Eriko; Hoshino, Kazuhiro; Takeuchi, Shuichi
2015-04-01
In this study, we developed and evaluated a portable digital holographic microscope (DHM) using a spherical reference beam. To reduce the size of this DHM, we replaced the objective lens with a small aspherical single lens, which produces the spherical reference beam. In addition, integrating the CCD camera and beam splitter yielded a simplified alignment along with further microscope compactness, resulting in a DHM with dimensions of 150 (W) × 470 (D) × 244.5 (H) mm3, which is a portable size. The spatial resolution of the developed DHM was evaluated and a value of 870 nm was experimentally obtained, similar to the theoretical resolution of 851 nm. In addition, we conducted measurements on leukemia cells to evaluate the applicability of our novel microscope to cystoscopy.
Novel radio-frequency ion trap with spherical geometry
Noshad, Houshyar
2014-01-01
Confinement of single ions in a novel radio-frequency (RF) quadrupole ion trap with spherical shape is investigated. An optimization of this spherical ion trap (SIT) is carried out in order to suppress its nonlinearity substantially by eliminating the electric octupole moment. Hence, a trapping potential and consequently an electric field very similar to the ideal quadrupole ion trap (QIT) are obtained. Afterwards, three stability regions for the optimized SIT are numerically computed. The regions coincide well with those reported in the literature for the ideal QIT. The reason is attributed to the zero electric octupole moment of our proposed trap. The SIT simple geometry and relative ease of fabrication along with its increased trapping volume compared to the conventional hyperbolic quadrupole ion trap, make it an appropriate choice for miniaturization.
Thermodynamic Volume Product in Spherically Symmetric and Axisymmetric Spacetime
Pradhan, Parthapratim
2016-01-01
In this Letter, we compute particularly thermodynamic \\emph{volume product, volume sum, volume minus and volume division} for wide variety of spherically symmetric spacetime and axisymmetric spacetime in the frame work of \\emph{extended phase space}. We consider Einstein gravity as well as other than Einstein gravity i.e. \\emph{Ho\\v{r}ava Lifshitz} gravity. We speculate that for spherically symmetric black holes the volume product is mass-independent both in Einstein gravity as well as Ho\\v{r}ava Lifshitz gravity while the other combination is mass-dependent. For axisymmetric black hole spacetime in Einstein gravity all the combination is \\emph{mass-dependent}. There has been no chance to generate any combination of volume product is mass-independent. Interestingly, \\emph{only rotating BTZ black hole} in 3D provides the volume product formula is mass-independent i.e. \\emph{universal} and hence it is quantized.
Ultrasmooth, Highly Spherical Monocrystalline Gold Particles for Precision Plasmonics
Lee, You-Jin
2013-12-23
Ultrasmooth, highly spherical monocrystalline gold particles were prepared by a cyclic process of slow growth followed by slow chemical etching, which selectively removes edges and vertices. The etching process effectively makes the surface tension isotropic, so that spheres are favored under quasi-static conditions. It is scalable up to particle sizes of 200 nm or more. The resulting spherical crystals display uniform scattering spectra and consistent optical coupling at small separations, even showing Fano-like resonances in small clusters. The high monodispersity of the particles we demonstrate should facilitate the self-assembly of nanoparticle clusters with uniform optical resonances, which could in turn be used to fabricate optical metafluids. Narrow size distributions are required to control not only the spectral features but also the morphology and yield of clusters in certain assembly schemes. © 2013 American Chemical Society.
Surface Plasmon Coupling and Control Using Spherical Cap Structures
Energy Technology Data Exchange (ETDEWEB)
Gong, Yu; Joly, Alan G.; Zhang, Xin; El-Khoury, Patrick Z.; Hess, Wayne P.
2017-06-05
Propagating surface plasmons (PSPs) launched from a protruded silver spherical cap structure are investigated using photoemission electron microscopy (PEEM) and finite difference time domain (FDTD) calculations. Our combined experimental and theoretical findings reveal that PSP coupling efficiency is comparable to conventional etched-in plasmonic coupling structures. Additionally, plasmon propagation direction can be varied by a linear rotation of the driving laser polarization. A simple geometric model is proposed in which the plasmon direction selectivity is proportional to the projection of the linear laser polarization on the surface normal. An application for the spherical cap coupler as a gate device is proposed. Overall, our results indicate that protruded cap structures hold great promise as elements in emerging surface plasmon applications.
AdS nonlinear instability: moving beyond spherical symmetry
Dias, Oscar J C
2016-01-01
Anti-de Sitter (AdS) is conjectured to be nonlinear unstable to a weakly turbulent mechanism that develops a cascade towards high frequencies, leading to black hole formation [1,2]. We give evidence that the gravitational sector of perturbations behaves differently from the scalar one studied in [2]. In contrast with [2], we find that not all gravitational normal modes of AdS can be nonlinearly extended into periodic horizonless smooth solutions of the Einstein equation. In particular, we show that even seeds with a single normal mode can develop secular resonances, unlike the spherically symmetric scalar field collapse studied in [2]. Moreover, if the seed has two normal modes, more than one resonance can be generated at third order, unlike the spherical collapse of [2]. We also show that weak turbulent perturbative theory predicts the existence of direct and inverse cascades, with the former dominating the latter for equal energy two-mode seeds.
Gravitational and electric energies in collapse of spherically thin capacitor
Ruffini, Remo
2013-01-01
In our previous article (PHYSICAL REVIEW D 86, 084004 (2012)), we present a study of strong oscillating electric fields and electron-positron pair-production in gravitational collapse of a neutral stellar core at or over nuclear densities. In order to understand the back-reaction of such electric energy building and radiating on collapse, we adopt a simplified model describing the collapse of a spherically thin capacitor to give an analytical description how gravitational energy is converted to both kinetic and electric energies in collapse. It is shown that (i) averaged kinetic and electric energies are the same order, about an half of gravitational energy of spherically thin capacitor in collapse; (ii) caused by radiating and rebuilding electric energy, gravitational collapse undergoes a sequence of "on and off" hopping steps in the microscopic Compton scale. Although such a collapse process is still continuous in terms of macroscopic scales, it is slowed down as kinetic energy is reduced and collapsing tim...