Finite groups and quantum physics

International Nuclear Information System (INIS)

Kornyak, V. V.

2013-01-01

Concepts of quantum theory are considered from the constructive “finite” point of view. The introduction of a continuum or other actual infinities in physics destroys constructiveness without any need for them in describing empirical observations. It is shown that quantum behavior is a natural consequence of symmetries of dynamical systems. The underlying reason is that it is impossible in principle to trace the identity of indistinguishable objects in their evolution—only information about invariant statements and values concerning such objects is available. General mathematical arguments indicate that any quantum dynamics is reducible to a sequence of permutations. Quantum phenomena, such as interference, arise in invariant subspaces of permutation representations of the symmetry group of a dynamical system. Observable quantities can be expressed in terms of permutation invariants. It is shown that nonconstructive number systems, such as complex numbers, are not needed for describing quantum phenomena. It is sufficient to employ cyclotomic numbers—a minimal extension of natural numbers that is appropriate for quantum mechanics. The use of finite groups in physics, which underlies the present approach, has an additional motivation. Numerous experiments and observations in the particle physics suggest the importance of finite groups of relatively small orders in some fundamental processes. The origin of these groups is unclear within the currently accepted theories—in particular, within the Standard Model.

Finite Groups with Given Quantitative Non-Nilpotent Subgroups II

DEFF Research Database (Denmark)

Shi, Jiangtao; Zhang, Cui

2014-01-01

As an extension of Shi and Zhang's 2011 article [4], we prove that any finite group having at most 23 non-normal non-nilpotent proper subgroups is solvable except for G ≅ A 5 or SL(2, 5), and any finite group having at most three conjugacy classes of non-normal non-nilpotent proper subgroups is s...

The Fibonacci-Padovan sequences in finite groups

Directory of Open Access Journals (Sweden)

Sait Tas

2014-11-01

Full Text Available The Fibonacci-Padovan sequence modulo m was studied. Also, the Fibonacci-Padovan orbits of -generator finite groups such that was examined. The Fibonacci-Padovan lengths of the groups , and for , where Z is integer, were then obtained.

Blocks of finite groups and their invariants

CERN Document Server

Sambale, Benjamin

2014-01-01

Providing a nearly complete selection of up-to-date methods and results on block invariants with respect to their defect groups, this book covers the classical theory pioneered by Brauer, the modern theory of fusion systems introduced by Puig, the geometry of numbers developed by Minkowski, the classification of finite simple groups, and various computer assisted methods. In a powerful combination, these tools are applied to solve many special cases of famous open conjectures in the representation theory of finite groups. Most of the material is drawn from peer-reviewed journal articles, but there are also new previously unpublished results. In order to make the text self-contained, detailed proofs are given whenever possible. Several tables add to the text's usefulness as a reference. The book is aimed at experts in group theory or representation theory who may wish to make use of the presented ideas in their research.

Sutherland models for complex reflection groups

International Nuclear Information System (INIS)

Crampe, N.; Young, C.A.S.

2008-01-01

There are known to be integrable Sutherland models associated to every real root system, or, which is almost equivalent, to every real reflection group. Real reflection groups are special cases of complex reflection groups. In this paper we associate certain integrable Sutherland models to the classical family of complex reflection groups. Internal degrees of freedom are introduced, defining dynamical spin chains, and the freezing limit taken to obtain static chains of Haldane-Shastry type. By considering the relation of these models to the usual BC N case, we are led to systems with both real and complex reflection groups as symmetries. We demonstrate their integrability by means of new Dunkl operators, associated to wreath products of dihedral groups

On the growth of rank for subgroups of finitely generated groups

International Nuclear Information System (INIS)

Osin, D V

1999-01-01

In [1] and [2] the functions of rank growth were independently introduced and investigated for subgroups of a finitely generated free group. In the present paper the concept of growth of rank is extended to subgroups of an arbitrary finitely generated group G, and the dependence of the asymptotic behaviour of the above functions on the choice of a finite generating set in G is studied. For a broad class of groups (which includes, in particular, the free polynilpotent groups) estimates for the growth of rank for subgroups are obtained that generalize the wellknown Baumslag-Eidel'kind result on finitely generated normal subgroups. Some problems related to the realization of arbitrary functions as functions of rank growth for subgroups of soluble groups are treated

On the structure of finite-sheeted coverings of compact connected groups

OpenAIRE

Grigorian, S. A.; Gumerov, R. N.

2004-01-01

Finite-sheeted covering mappings onto compact connected groups are studied. It is shown that a finite-sheeted covering mapping from a connected Hausdorff topological space onto a compact connected abelian group G must be a homeomorphism provided that the character group of G admits division by the degree of given covering mapping. Using this result, we obtain criteria of triviality for finite coverings of G in terms of its character group and means on G. In order to establish these facts, for...

n-th Roots in finite polyhedral and centro-polyhedral groups

Indian Academy of Sciences (India)

Probability in finite groups; roots of elements; polyhedral groups; centro- polyhedral groups. 2010 Mathematics ... An element g of a finite group G is said to have an n-th root if there exists an element h ∈ G such that g = hn (n is a ..... For the proof of the fourth part, we must consider two cases: (i) m is odd and 4|d,. (ii) m, d are ...

Finite groups with the set of the number of subgroups of possible ...

Indian Academy of Sciences (India)

Finite group; the number of subgroups of possible order. 1. Introduction. Throughout this paper, groups mentioned are finite and p is a prime. An important topic in the group theory is to investigate the number of subgroups of possible order, and con- versely it is also an important subject to determine the structure of a finite ...

Group-invariant finite Fourier transforms

International Nuclear Information System (INIS)

Shenefelt, M.H.

1988-01-01

The computation of the finite Fourier transform of functions is one of the most used computations in crystallography. Since the Fourier transform involved in 3-dimensional, the size of the computation becomes very large even for relatively few sample points along each edge. In this thesis, there is a family of algorithms that reduce the computation of Fourier transform of functions respecting the symmetries. Some properties of these algorithms are: (1) The algorithms make full use of the group of symmetries of a crystal. (2) The algorithms can be factored and combined according to the prime factorization of the number of points in the sample space. (3) The algorithms are organized into a family using the group structure of the crystallographic groups to make iterative procedures possible

The Finite Heisenberg-Weyl Groups in Radar and Communications

Directory of Open Access Journals (Sweden)

Calderbank AR

2006-01-01

Full Text Available We investigate the theory of the finite Heisenberg-Weyl group in relation to the development of adaptive radar and to the construction of spreading sequences and error-correcting codes in communications. We contend that this group can form the basis for the representation of the radar environment in terms of operators on the space of waveforms. We also demonstrate, following recent developments in the theory of error-correcting codes, that the finite Heisenberg-Weyl groups provide a unified basis for the construction of useful waveforms/sequences for radar, communications, and the theory of error-correcting codes.

Introduction to orthogonal, symplectic and unitary representations of finite groups

CERN Document Server

Riehm, Carl R

2011-01-01

Orthogonal, symplectic and unitary representations of finite groups lie at the crossroads of two more traditional subjects of mathematics-linear representations of finite groups, and the theory of quadratic, skew symmetric and Hermitian forms-and thus inherit some of the characteristics of both. This book is written as an introduction to the subject and not as an encyclopaedic reference text. The principal goal is an exposition of the known results on the equivalence theory, and related matters such as the Witt and Witt-Grothendieck groups, over the "classical" fields-algebraically closed, rea

A family of dominant Fitting classes of finite soluble groups

OpenAIRE

Ballester-Bolinches, A; Martínez Pastor, Ana; Pérez-Ramos, M.D.

1998-01-01

In this paper a large family of dominant Fitting classes of finite soluble groups and the description of the corresponding injectors are obtained. Classical constructions of nilpotent and Lockett injectors as well as p-nilpotent injectors arise as particular cases. DGICYT, Ministerio de Educacion y Ciencia of Spain [ Proyecto PB 94-0965] Ballester-Bolinches, A.; Martínez Pastor, A.; Pérez-Ramos, M. (1998). A family of dominant Fitting classes of finite soluble groups. Journal of t...

A computational note on finite groups with two generators

International Nuclear Information System (INIS)

Saeed-ul-Islam, M.

1983-12-01

Finite groups with two independent generators attracted the attention of mathematicians during 1940-1959. These groups are subgroups of SU(n) and an interest is now being shown in these groups by particle physicists. In this note we give a brief history of these groups and announce some of the computations done by using a computer. (author)

The effects of core-reflected waves on finite fault inversions with teleseismic body wave data

Science.gov (United States)

Qian, Yunyi; Ni, Sidao; Wei, Shengji; Almeida, Rafael; Zhang, Han

2017-11-01

Teleseismic body waves are essential for imaging rupture processes of large earthquakes. Earthquake source parameters are usually characterized by waveform analyses such as finite fault inversions using only turning (direct) P and SH waves without considering the reflected phases from the core-mantle boundary (CMB). However, core-reflected waves such as ScS usually have amplitudes comparable to direct S waves due to the total reflection from the CMB and might interfere with the S waves used for inversion, especially at large epicentral distances for long duration earthquakes. In order to understand how core-reflected waves affect teleseismic body wave inversion results, we develop a procedure named Multitel3 to compute Green's functions that contain turning waves (direct P, pP, sP, direct S, sS and reverberations in the crust) and core-reflected waves (PcP, pPcP, sPcP, ScS, sScS and associated reflected phases from the CMB). This ray-based method can efficiently generate synthetic seismograms for turning and core-reflected waves independently, with the flexibility to take into account the 3-D Earth structure effect on the timing between these phases. The performance of this approach is assessed through a series of numerical inversion tests on synthetic waveforms of the 2008 Mw7.9 Wenchuan earthquake and the 2015 Mw7.8 Nepal earthquake. We also compare this improved method with the turning-wave only inversions and explore the stability of the new procedure when there are uncertainties in a priori information (such as fault geometry and epicentre location) or arrival time of core-reflected phases. Finally, a finite fault inversion of the 2005 Mw8.7 Nias-Simeulue earthquake is carried out using the improved Green's functions. Using enhanced Green's functions yields better inversion results as expected. While the finite source inversion with conventional P and SH waves is able to recover large-scale characteristics of the earthquake source, by adding PcP and ScS phases

Central extensions of some Abelian finite gauge groups

International Nuclear Information System (INIS)

Combe, Ph.; Rodriguez, R.; Sirugue, M.; Sirugue-Collin, M.

1981-01-01

The authors describe central extensions of Abelian finite gauge groups on lattices which are permutation invariant. Moreover some remarks are made on the gauge models on lattice associated with these non-commutative central extensions. (Auth.)

Group Journaling: A Tool for Reflection, Fun and Group Development

Science.gov (United States)

Asfeldt, Morten

2012-01-01

Personal journaling is common practice in outdoor programs and is an important means of reflection and meaning-making. For over 20 years the author has used group journals to promote reflection and understanding, raise important questions, explore difficult issues, develop writing and speaking skills, and enhance group development. In this…

The Polytopic-k-Step Fibonacci Sequences in Finite Groups

Directory of Open Access Journals (Sweden)

Ömür Deveci

2011-01-01

Full Text Available We study the polytopic-k-step Fibonacci sequences, the polytopic-k-step Fibonacci sequences modulo m, and the polytopic-k-step Fibonacci sequences in finite groups. Also, we examine the periods of the polytopic-k-step Fibonacci sequences in semidihedral group SD2m.

Reflection group on 'Expert Culture'

International Nuclear Information System (INIS)

Eggermont, G.

2000-01-01

As part of SCK-CEN's social sciences and humanities programme, a reflection group on 'Expert Culture' was established. The objectives of the reflection group are: (1) to clarify the role of SCK-CEN experts; (2) to clarify the new role of expertise in the evolving context of risk society; (3) to confront external views and internal SCK-CEN experiences on expert culture; (4) to improve trust building of experts and credibility of SCK-CEN as a nuclear actor in society; (5) to develop a draft for a deontological code; (6) to integrate the approach in training on assertivity and communication; (7) to create an output for a topical day on the subject of expert culture. The programme, achievements and perspectives of the refection group are summarised

Reflection and Transmission of a Focused Finite Amplitude Sound Beam Incident on a Curved Interface

Science.gov (United States)

Makin, Inder Raj Singh

Reflection and transmission of a finite amplitude focused sound beam at a weakly curved interface separating two fluid-like media are investigated. The KZK parabolic wave equation, which accounts for thermoviscous absorption, diffraction, and nonlinearity, is used to describe the high intensity focused beam. The first part of the work deals with the quasilinear analysis of a weakly nonlinear beam after its reflection and transmission from a curved interface. A Green's function approach is used to define the field integrals describing the primary and the nonlinearly generated second harmonic beam. Closed-form solutions are obtained for the primary and second harmonic beams when a Gaussian amplitude distribution at the source is assumed. The second part of the research uses a numerical frequency domain solution of the KZK equation for a fully nonlinear analysis of the reflected and transmitted fields. Both piston and Gaussian sources are considered. Harmonic components generated in the medium due to propagation of the focused beam are evaluated, and formation of shocks in the reflected and transmitted beams is investigated. A finite amplitude focused beam is observed to be modified due to reflection and transmission from a curved interface in a manner distinct from that in the case of a small signal beam. Propagation curves, beam patterns, phase plots and time waveforms for various parameters defining the source and media pairs are presented, highlighting the effect of the interface curvature on the reflected and transmitted beams. Relevance of the current work to biomedical applications of ultrasound is discussed.

On the total character of finite groups

Directory of Open Access Journals (Sweden)

Sunil Kumar Prajapati

2014-09-01

Full Text Available For a finite group $G$, we study the total character $tau_G$ afforded by the direct sum of all the non-isomorphic irreducible complex representations of $G$. We resolve for several classes of groups (the Camina $p$-groups, the generalized Camina $p$-groups, the groups which admit $(G,Z(G$ as a generalized Camina pair, the problem of existence of a polynomial $f(x in mathbb{Q}[x]$ such that $f(chi = tau_G$ for some irreducible character $chi$ of $G$. As a consequence, we completely determine the $p$-groups of order at most $p^5$ (with $p$ odd which admit such a polynomial. We deduce the characterization that these are the groups $G$ for which $Z(G$ is cyclic and $(G,Z(G$ is a generalized Camina pair and, we conjecture that this holds good for $p$-groups of any order.

Irreducible quantum group modules with finite dimensional weight spaces

DEFF Research Database (Denmark)

Pedersen, Dennis Hasselstrøm

a finitely generated U q -module which has finite dimensional weight spaces and is a sum of those. Our approach follows the procedures used by S. Fernando and O. Mathieu to solve the corresponding problem for semisimple complex Lie algebra modules. To achieve this we have to overcome a number of obstacles...... not present in the classical case. In the process we also construct twisting functors rigerously for quantum group modules, study twisted Verma modules and show that these admit a Jantzen filtration with corresponding Jantzen sum formula....

Reflection Positive Stochastic Processes Indexed by Lie Groups

Science.gov (United States)

Jorgensen, Palle E. T.; Neeb, Karl-Hermann; Ólafsson, Gestur

2016-06-01

Reflection positivity originates from one of the Osterwalder-Schrader axioms for constructive quantum field theory. It serves as a bridge between euclidean and relativistic quantum field theory. In mathematics, more specifically, in representation theory, it is related to the Cartan duality of symmetric Lie groups (Lie groups with an involution) and results in a transformation of a unitary representation of a symmetric Lie group to a unitary representation of its Cartan dual. In this article we continue our investigation of representation theoretic aspects of reflection positivity by discussing reflection positive Markov processes indexed by Lie groups, measures on path spaces, and invariant gaussian measures in spaces of distribution vectors. This provides new constructions of reflection positive unitary representations.

Finite Heisenberg groups and Seiberg dualities in quiver gauge theories

International Nuclear Information System (INIS)

Burrington, Benjamin A.; Liu, James T.; Mahato, Manavendra; Pando Zayas, Leopoldo A.

2006-01-01

A large class of quiver gauge theories admits the action of finite Heisenberg groups of the form Heis(Z q xZ q ). This Heisenberg group is generated by a manifest Z q shift symmetry acting on the quiver along with a second Z q rephasing (clock) generator acting on the links of the quiver. Under Seiberg duality, however, the action of the shift generator is no longer manifest, as the dualized node has a different structure from before. Nevertheless, we demonstrate that the Z q shift generator acts naturally on the space of all Seiberg dual phases of a given quiver. We then prove that the space of Seiberg dual theories inherits the action of the original finite Heisenberg group, where now the shift generator Z q is a map among fields belonging to different Seiberg phases. As examples, we explicitly consider the action of the Heisenberg group on Seiberg phases for C 3 /Z 3 , Y 4,2 and Y 6,3 quivers

Experimental Investigation of Propagation and Reflection Phenomena in Finite Amplitude Sound Beams.

Science.gov (United States)

Averkiou, Michalakis Andrea

Measurements of finite amplitude sound beams are compared with theoretical predictions based on the KZK equation. Attention is devoted to harmonic generation and shock formation related to a variety of propagation and reflection phenomena. Both focused and unfocused piston sources were used in the experiments. The nominal source parameters are piston radii of 6-25 mm, frequencies of 1-5 MHz, and focal lengths of 10-20 cm. The research may be divided into two parts: propagation and reflection of continuous-wave focused sound beams, and propagation of pulsed sound beams. In the first part, measurements of propagation curves and beam patterns of focused pistons in water, both in the free field and following reflection from curved targets, are presented. The measurements are compared with predictions from a computer model that solves the KZK equation in the frequency domain. A novel method for using focused beams to measure target curvature is developed. In the second part, measurements of pulsed sound beams from plane pistons in both water and glycerin are presented. Very short pulses (less than 2 cycles), tone bursts (5-30 cycles), and frequency modulated (FM) pulses (10-30 cycles) were measured. Acoustic saturation of pulse propagation in water is investigated. Self-demodulation of tone bursts and FM pulses was measured in glycerin, both in the near and far fields, on and off axis. All pulse measurements are compared with numerical results from a computer code that solves the KZK equation in the time domain. A quasilinear analytical solution for the entire axial field of a self-demodulating pulse is derived in the limit of strong absorption. Taken as a whole, the measurements provide a broad data base for sound beams of finite amplitude. Overall, outstanding agreement is obtained between theory and experiment.

Quasirecognition by prime graph of finite simple groups ${}^2D_n(3$

Directory of Open Access Journals (Sweden)

Behrooz Khosravi

2014-12-01

Full Text Available Let $G$ be a finite group. In [Ghasemabadi et al., characterizations of the simple group ${}^2D_n(3$ by prime graph and spectrum, Monatsh Math., 2011] it is proved that if $n$ is odd, then ${}^2D _n(3$ is recognizable by prime graph and also by element orders. In this paper we prove that if $n$ is even, then $D={}^2D_{n}(3$ is quasirecognizable by prime graph, i.e. every finite group $G$ with $Gamma(G=Gamma(D$ has a unique nonabelian composition factor and this factor is isomorphic to $D$.

A course in finite group representation theory

CERN Document Server

Webb, Peter

2016-01-01

This graduate-level text provides a thorough grounding in the representation theory of finite groups over fields and rings. The book provides a balanced and comprehensive account of the subject, detailing the methods needed to analyze representations that arise in many areas of mathematics. Key topics include the construction and use of character tables, the role of induction and restriction, projective and simple modules for group algebras, indecomposable representations, Brauer characters, and block theory. This classroom-tested text provides motivation through a large number of worked examples, with exercises at the end of each chapter that test the reader's knowledge, provide further examples and practice, and include results not proven in the text. Prerequisites include a graduate course in abstract algebra, and familiarity with the properties of groups, rings, field extensions, and linear algebra.

The classification of finite simple groups groups of characteristic 2 type

CERN Document Server

Aschbacher, Michael; Smith, Stephen D; Solomon, Ronald

2011-01-01

The book provides an outline and modern overview of the classification of the finite simple groups. It primarily covers the "even case", where the main groups arising are Lie-type (matrix) groups over a field of characteristic 2. The book thus completes a project begun by Daniel Gorenstein's 1983 book, which outlined the classification of groups of "noncharacteristic 2 type". However, this book provides much more. Chapter 0 is a modern overview of the logical structure of the entire classification. Chapter 1 is a concise but complete outline of the "odd case" with updated references, while Chapter 2 sets the stage for the remainder of the book with a similar outline of the "even case". The remaining six chapters describe in detail the fundamental results whose union completes the proof of the classification theorem. Several important subsidiary results are also discussed. In addition, there is a comprehensive listing of the large number of papers referenced from the literature. Appendices provide a brief but ...

Method for the determination of Clebsch-Gordan coefficients of finite magnetic groups

NARCIS (Netherlands)

van den Broek, P.M.; Horowitz, L.P.; Ne'eman, Y.

1980-01-01

A recent method for the determination of Clebsch-Gordan coefficients of finite magnetic groups is generalised to magnetic groups. Discussion is restricted to unitary-anti-unitary representations of type I.

Interaction of a finite-length ion beam with a background plasma: Reflected ions at the quasi-parallel bow shock

International Nuclear Information System (INIS)

Onsager, T.G.; Winske, D.; Thomsen, M.F.

1991-01-01

The coupling of a finite-length, field-aligned, ion beam with a uniform background plasma is investigated using one-dimensional hybrid computer simulations. The finite-length beam is used to study the interaction between the incident solar wind and ions reflected from the Earth's quasi-parallel bow shock, where the reflection process may vary with time. The coupling between the reflected ions and the solar wind is relevant to ion heating at the bow shock and possibly to the formation of hot, flow anomalies and re-formation of the shock itself. The authors find that although there are many similarities between the instabilities driven by the finite-length beam and those predicted by linear theory for an infinite, homogeneous beam, there are also some important differences. Consistent with linear theory, the waves which dominate the interaction are the electromagnetic right-hand polarized resonant and nonresonant modes. However, in addition to the instability growth rates, the length of time that the waves are in contact with the beam is also an important factor in determining which wave mode will dominate the interaction. Whereas linear theory predicts the nonresonant mode to have the larger growth rate for the parameters they investigate, with finite-length beam they find that both the nonresonant and resonant modes contribute to the interaction. They find that the interaction will result in strong coupling, where a significant fraction of the available free energy is converted into thermal energy in a short time, provided the beam is sufficiently dense or sufficiently long

Numerical solution of multi group-Two dimensional- Adjoint equation with finite element method

International Nuclear Information System (INIS)

Poursalehi, N.; Khalafi, H.; Shahriari, M.; Minoochehr

2008-01-01

Adjoint equation is used for perturbation theory in nuclear reactor design. For numerical solution of adjoint equation, usually two methods are applied. These are Finite Element and Finite Difference procedures. Usually Finite Element Procedure is chosen for solving of adjoint equation, because it is more use able in variety of geometries. In this article, Galerkin Finite Element method is discussed. This method is applied for numerical solving multi group, multi region and two dimensional (X, Y) adjoint equation. Typical reactor geometry is partitioned with triangular meshes and boundary condition for adjoint flux is considered zero. Finally, for a case of defined parameters, Finite Element Code was applied and results were compared with Citation Code

Magma Proof of Strict Inequalities for Minimal Degrees of Finite Groups

OpenAIRE

Murray, Scott H.; Saunders, Neil

2009-01-01

The minimal faithful permutation degree of a finite group $G$, denote by $\\mu(G)$ is the least non-negative integer $n$ such that $G$ embeds inside the symmetric group $\\Sym(n)$. In this paper, we outline a Magma proof that 10 is the smallest degree for which there are groups $G$ and $H$ such that $\\mu(G \\times H) < \\mu(G)+ \\mu(H)$.

A diagram approach to character formulae for finite and compact groups

International Nuclear Information System (INIS)

Kibler, M.; Elbaz, E.

1978-06-01

Some basic relations for the representation theory and the Wigner-Racah algebra of a finite or compact continuous group are discussed and transcribed in terms of diagrams. Special emphasis is placed on the case of a simply reducible group and all the diagrams are applicable to SU 2 without any change

A non-reflecting boundary for use in a finite element beam model of a railway track

Science.gov (United States)

Yang, Jiannan; Thompson, David J.

2015-02-01

Some beam-like structures such as a railway track are effectively infinite in nature. Analytical solutions exist for simple structures but numerical methods like the finite element (FE) method are often employed to study more complicated problems. However, when the FE method is used for structures of infinite extent it is essential to introduce artificial boundaries to limit the area of computation. Here, a non-reflecting boundary is developed using a damped tapered tip for application in a finite element model representing an infinite supported beam. The FE model of the tapered tip is validated against an analytical model based on Bessel functions. The reflection characteristics of the FE tapered tip are quantified using a wave/FE superposition method. It is shown that the damped tapered tip is much more effective than its constant counterpart and achieves reduction of the model size. The damped tapered tip is applied to a simple FE railway track model and good agreement is found when its point mobility is compared with an analytical infinite track model.

A generalized Frattini subgroup of a finite group

Directory of Open Access Journals (Sweden)

Prabir Bhattacharya

1989-01-01

Full Text Available For a finite group G and an arbitrary prime p, let SP(G denote the intersection of all maximal subgroups M of G such that [G:M] is both composite and not divisible by p; if no such M exists we set SP(G = G. Some properties of G are considered involving SP(G. In particular, we obtain a characterization of G when each M in the definition of SP(G is nilpotent.

Finite groups all of whose minimal subgroups are NE-subgroups

Indian Academy of Sciences (India)

Logo of the Indian Academy of Sciences. Indian Academy of Sciences ... In this article, we investigate the structure of under the assumption that subgroups of prime order are *-subgroups of . The finite groups, all of whose minimal subgroups of the generalized Fitting subgroup are *-subgroups are classified.

Classification of finite reparametrization symmetry groups in the three-Higgs-doublet model

International Nuclear Information System (INIS)

Ivanov, Igor P.; Vdovin, E.

2013-01-01

Symmetries play a crucial role in electroweak symmetry breaking models with non-minimal Higgs content. Within each class of these models, it is desirable to know which symmetry groups can be implemented via the scalar sector. In N-Higgs-doublet models, this classification problem was solved only for N=2 doublets. Very recently, we suggested a method to classify all realizable finite symmetry groups of Higgs-family transformations in the three-Higgs-doublet model (3HDM). Here, we present this classification in all detail together with an introduction to the theory of solvable groups, which play the key role in our derivation. We also consider generalized-CP symmetries, and discuss the interplay between Higgs-family symmetries and CP-conservation. In particular, we prove that presence of the Z 4 symmetry guarantees the explicit CP-conservation of the potential. This work completes classification of finite reparametrization symmetry groups in 3HDM. (orig.)

Solution of the diffusion equations for several groups by the finite elements method

International Nuclear Information System (INIS)

Arredondo S, C.

1975-01-01

The code DELFIN has been implemented for the solution of the neutrons diffusion equations in two dimensions obtained by applying the approximation of several groups of energy. The code works with any number of groups and regions, and can be applied to thermal reactors as well as fast reactor. Providing it with the diffusion coefficients, the effective sections and the fission spectrum we obtain the results for the systems multiplying constant and the flows of each groups. The code was established using the method of finite elements, which is a form of resolution of the variational formulation of the equations applying the Ritz-Galerkin method with continuous polynomial functions by parts, in one case of the Lagrange type with rectangular geometry and up to the third grade. The obtained results and the comparison with the results in the literature, permit to reach the conclusion that it is convenient, to use the rectangular elements in all the cases where the geometry permits it, and demonstrate also that the finite elements method is better than the finite differences method. (author)

Sparkling feather reflections of a bird-of-paradise explained by finite-difference time-domain modeling.

Science.gov (United States)

Wilts, Bodo D; Michielsen, Kristel; De Raedt, Hans; Stavenga, Doekele G

2014-03-25

Birds-of-paradise are nature's prime examples of the evolution of color by sexual selection. Their brilliant, structurally colored feathers play a principal role in mating displays. The structural coloration of both the occipital and breast feathers of the bird-of-paradise Lawes' parotia is produced by melanin rodlets arranged in layers, together acting as interference reflectors. Light reflection by the silvery colored occipital feathers is unidirectional as in a classical multilayer, but the reflection by the richly colored breast feathers is three-directional and extraordinarily complex. Here we show that the reflection properties of both feather types can be quantitatively explained by finite-difference time-domain modeling using realistic feather anatomies and experimentally determined refractive index dispersion values of keratin and melanin. The results elucidate the interplay between avian coloration and vision and indicate tuning of the mating displays to the spectral properties of the avian visual system.

Reflection group on 'Expert Culture'

Energy Technology Data Exchange (ETDEWEB)

Eggermont, G

2000-07-01

As part of SCK-CEN's social sciences and humanities programme, a reflection group on 'Expert Culture' was established. The objectives of the reflection group are: (1) to clarify the role of SCK-CEN experts; (2) to clarify the new role of expertise in the evolving context of risk society; (3) to confront external views and internal SCK-CEN experiences on expert culture; (4) to improve trust building of experts and credibility of SCK-CEN as a nuclear actor in society; (5) to develop a draft for a deontological code; (6) to integrate the approach in training on assertivity and communication; (7) to create an output for a topical day on the subject of expert culture. The programme, achievements and perspectives of the refection group are summarised.

On Non-Frattini Chief Factors and Solvability of Finite Groups

Indian Academy of Sciences (India)

A subgroup of a group is said to be a semi C A P ∗ -subgroup of if there is a chief series 1 = G 0 < G 1 < ⋯ < G m = G of such that for every non-Frattini chief factor G i / G i − 1 , H either covers G i / G i − 1 or avoids G i / G i − 1 . In this paper, some sufficient conditions for a normal subgroup of a finite group to be ...

How to succeed with ethics reflection groups in community healthcare? Professionals' perceptions.

Science.gov (United States)

Karlsen, Heidi; Lillemoen, Lillian; Magelssen, Morten; Førde, Reidun; Pedersen, Reidar; Gjerberg, Elisabeth

2018-01-01

Healthcare personnel in the municipal healthcare systems experience many ethical challenges in their everyday work. In Norway, 243 municipalities participated in a national ethics project, aimed to increase ethical competence in municipal healthcare services. In this study, we wanted to map out what participants in ethics reflection groups experienced as promoters or as barriers to successful reflection. To examine what the staff experience as promoters or as barriers to successful ethics reflection. The study has a qualitative design, where 56 participants in municipal healthcare participated in 10 different focus-group interviews. Ethical considerations: The data collection was based on the participants' informed consent and approved by the Data Protection Official of the Norwegian Centre for Research Data. The informants had different experiences from ethics reflection group. Nevertheless, we found that there were several factors that were consistently mentioned: competence, facilitator's role, ethics reflection groups organizing, and organizational support were all experienced as promoters and as a significant effect on ethics reflection groups. The absence of such factors would constitute important barriers to successful ethics reflection. The results are coincident with other studies, and indicate some conditions that may increase the possibility to succeed with ethics reflection groups. A systematic approach seems to be important, the systematics of the actual reflections, but also in the organization of ethics reflection group at the workplace. Community healthcare is characterized by organizational instabilities as many vacancies, high workloads, and lack of predictability. This can be a hinder for ethics reflection group. Both internal and external factors seem to influence the organization of ethics reflection group. The municipalities' instabilities challenging this work, and perceived as a clear inhibitor for the development. The participants

On the labeling and symmetry adaptation of the solvable finite groups representations

International Nuclear Information System (INIS)

Caride, A.O.; Zanette, S.I.; Nogueira, S.R.A.

1987-01-01

We propose a method to simultaneously perform a symmetry adaptation and a labeling of the bases of the irreducible representations of the solvable finite groups. It is performed by difining a self-adjoint operator with ligenvalues which evidence the descent in symmetry of the group-subgroups sequences. We also prove two theorems on the canonicity of the cpomposition series of the solvable groups. (author) [pt

Reflection Group on 'Ethical Choices in Radiation Protection'

International Nuclear Information System (INIS)

Eggermont, G.

2000-01-01

As part of SCK-CEN's social sciences and humanities programme, a reflection group on 'Ethical Choices in Radiation Protection' was created. The objectives of the reflection group are (1) to brainstorm on critical issues of radiation protection; (2) to create a discussion forum with a variety os SCK-CEN researchers and external experts; (3) to make value judgements and open questions in radiation protection explicit; (4) to create an output for a topical day or workshop by editing a 'cahier' of contributed articles and discussion reports; (5) to complement the output of the SCK-CEN contribution in international ALARA workshops. The programme, achievements and perspectives of the refection group are summarised

Expansion in finite simple groups of Lie type

CERN Document Server

Tao, Terence

2015-01-01

Expander graphs are an important tool in theoretical computer science, geometric group theory, probability, and number theory. Furthermore, the techniques used to rigorously establish the expansion property of a graph draw from such diverse areas of mathematics as representation theory, algebraic geometry, and arithmetic combinatorics. This text focuses on the latter topic in the important case of Cayley graphs on finite groups of Lie type, developing tools such as Kazhdan's property (T), quasirandomness, product estimates, escape from subvarieties, and the Balog-Szemerédi-Gowers lemma. Applications to the affine sieve of Bourgain, Gamburd, and Sarnak are also given. The material is largely self-contained, with additional sections on the general theory of expanders, spectral theory, Lie theory, and the Lang-Weil bound, as well as numerous exercises and other optional material.

Heterogeneous Two-group Diffusion Theory for a Finite Cylindrical Reactor

Energy Technology Data Exchange (ETDEWEB)

Jonsson, Alf; Naeslund, Goeran

1961-06-15

The source and sink method given by Feinberg and Galanin is extended to a finite cylindrical reactor. The two-group diffusion theory formulation is chosen primarily because of the relatively simple formulae emerging. A machine programme, calculating the criticality constant thermal utilization and the relative number of thermal absorptions in fuel rods, has been developed for the Ferranti-Mercury Computer.

Reflection groups established by the ASN

International Nuclear Information System (INIS)

Fournier, M.

2009-01-01

Recent observations about tritium bio-kinetics in aquatic organisms might change our usual consideration about its radio-toxicity. In order to analyse these observations more thoroughly, the French nuclear safety authority (ASN) decided at the end of the year 2007 to create two independent reflection groups gathering scientists, nuclear operators and associations: the group 'tritium impact' has in charge the establishment of a status of the scientific knowledge relative to tritium sanitary impact, while the group 'defense in depth' has in charge the examination of the technical possibilities of tritium reprocessing and the establishment of a knowledge status of its environmental impact. First meetings of both groups took place in May 2008. Abstract only. (J.S.)

Some applications of the representation theory of finite groups. A partial reduction methof

NARCIS (Netherlands)

Zanten, Arend Jan van

1972-01-01

In this thesis we study the representation theory of finite groups and more specifically some aspects of the theory of characters. The technique of symmetrization and/or antisymmetrization of Kronecker powers of representations, which is well-known for the general linear group is applied here to

[Self-Reflection From Group Dialogue: The Lived Experience of Psychiatric/Mental Health Nurses].

Science.gov (United States)

Chiang, Hsien-Hsien

2015-08-01

Self-reflection is an essential element of reflective practice for group facilitators. However, this element typically exists largely at the personal level and is not addressed in group dialogues of nurses. The purpose of this study was to explore the self-reflection of psychiatric nurses in a supervision group. A phenomenological approach was used to investigate the dialogues across 12 sessions in terms of discussion content and the reflective journals of the psychiatric nurse participants. The findings showed that two forms of self-reflection included: Embodied self-reflection derived from the physical sensibility and discursive self-reflection derived from the group dialogues. The embodied and discursive self-reflections promote self-awareness in nurses. The embodiment and initiation in the group facilitates the process of self-becoming through the group dialogue, which promotes self-examination and self-direction in healthcare professionals.

Ethics reflection groups in community health services: an evaluation study.

Science.gov (United States)

Lillemoen, Lillian; Pedersen, Reidar

2015-04-17

Systematic ethics support in community health services in Norway is in the initial phase. There are few evaluation studies about the significance of ethics reflection on care. The aim of this study was to evaluate systematic ethics reflection in groups in community health (including nursing homes and residency), - from the perspectives of employees participating in the groups, the group facilitators and the service managers. The reflection groups were implemented as part of a research and development project. A mixed-methods design with qualitative focus group interviews, observations and written reports were used to evaluate. The study was conducted at two nursing homes, two home care districts and a residence for people with learning disabilities. Participants were employees, facilitators and service managers. The study was guided by ethical standard principles and was approved by the Norwegian Social Science Data Services. We found support for ethics reflection as a valuable measure to strengthen clinical practice. New and improved solutions, more cooperation between employees, and improved collaboration with patients and their families are some of the results. No negative experiences were found. Instead, the ethics reflection based on experiences and challenges in the workplace, was described as a win-win situation. The evaluation also revealed what is needed to succeed and useful tips for further development of ethics support in community health services. Ethics reflection groups focusing on ethical challenges from the participants' daily work were found to be significant for improved practice, collegial support and cooperation, personal and professional development among staff, facilitators and managers. Resources needed to succeed were managerial support, and anchoring ethics sessions in the routine of daily work.

The significance of ethics reflection groups in mental health care: a focus group study among health care professionals.

Science.gov (United States)

Hem, Marit Helene; Molewijk, Bert; Gjerberg, Elisabeth; Lillemoen, Lillian; Pedersen, Reidar

2018-06-05

Professionals within the mental health services face many ethical dilemmas and challenging situations regarding the use of coercion. The purpose of this study was to evaluate the significance of participating in systematic ethics reflection groups focusing on ethical challenges related to coercion. In 2013 and 2014, 20 focus group interviews with 127 participants were conducted. The interviews were tape recorded and transcribed verbatim. The analysis is inspired by the concept of 'bricolage' which means our approach was inductive. Most participants report positive experiences with participating in ethics reflection groups: A systematic and well-structured approach to discuss ethical challenges, increased consciousness of formal and informal coercion, a possibility to challenge problematic concepts, attitudes and practices, improved professional competence and confidence, greater trust within the team, more constructive disagreement and room for internal critique, less judgmental reactions and more reasoned approaches, and identification of potential for improvement and alternative courses of action. On several wards, the participation of psychiatrists and psychologists in the reflection groups was missing. The impact of the perceived lack of safety in reflection groups should not be underestimated. Sometimes the method for ethics reflection was utilised in a rigid way. Direct involvement of patients and family was missing. This focus group study indicates the potential of ethics reflection groups to create a moral space in the workplace that promotes critical, reflective and collaborative moral deliberations. Future research, with other designs and methodologies, is needed to further investigate the impact of ethics reflection groups on improving health care practices.

Practicing What We Preach: Teacher Reflection Groups on Cooperative Learning

Science.gov (United States)

Farrell, Thomas S. C.; Jacobs, George M.

2016-01-01

This article discusses the use of teacher reflection groups to aid teachers in their efforts to facilitate cooperative learning among their students. It is argued that these teacher reflection groups function best when they are organized with reference to eight cooperative learning principles. Furthermore, it is suggested that these reflective…

Numerical renormalization group method for entanglement negativity at finite temperature

Science.gov (United States)

Shim, Jeongmin; Sim, H.-S.; Lee, Seung-Sup B.

2018-04-01

We develop a numerical method to compute the negativity, an entanglement measure for mixed states, between the impurity and the bath in quantum impurity systems at finite temperature. We construct a thermal density matrix by using the numerical renormalization group (NRG), and evaluate the negativity by implementing the NRG approximation that reduces computational cost exponentially. We apply the method to the single-impurity Kondo model and the single-impurity Anderson model. In the Kondo model, the negativity exhibits a power-law scaling at temperature much lower than the Kondo temperature and a sudden death at high temperature. In the Anderson model, the charge fluctuation of the impurity contributes to the negativity even at zero temperature when the on-site Coulomb repulsion of the impurity is finite, while at low temperature the negativity between the impurity spin and the bath exhibits the same power-law scaling behavior as in the Kondo model.

Modeling the bidirectional reflectance distribution function of mixed finite plant canopies and soil

Science.gov (United States)

Schluessel, G.; Dickinson, R. E.; Privette, J. L.; Emery, W. J.; Kokaly, R.

1994-01-01

An analytical model of the bidirectional reflectance for optically semi-infinite plant canopies has been extended to describe the reflectance of finite depth canopies contributions from the underlying soil. The model depends on 10 independent parameters describing vegetation and soil optical and structural properties. The model is inverted with a nonlinear minimization routine using directional reflectance data for lawn (leaf area index (LAI) is equal to 9.9), soybeans (LAI, 2.9) and simulated reflectance data (LAI, 1.0) from a numerical bidirectional reflectance distribution function (BRDF) model (Myneni et al., 1988). While the ten-parameter model results in relatively low rms differences for the BRDF, most of the retrieved parameters exhibit poor stability. The most stable parameter was the single-scattering albedo of the vegetation. Canopy albedo could be derived with an accuracy of less than 5% relative error in the visible and less than 1% in the near-infrared. Sensitivity were performed to determine which of the 10 parameters were most important and to assess the effects of Gaussian noise on the parameter retrievals. Out of the 10 parameters, three were identified which described most of the BRDF variability. At low LAI values the most influential parameters were the single-scattering albedos (both soil and vegetation) and LAI, while at higher LAI values (greater than 2.5) these shifted to the two scattering phase function parameters for vegetation and the single-scattering albedo of the vegetation. The three-parameter model, formed by fixing the seven least significant parameters, gave higher rms values but was less sensitive to noise in the BRDF than the full ten-parameter model. A full hemispherical reflectance data set for lawn was then interpolated to yield BRDF values corresponding to advanced very high resolution radiometer (AVHRR) scan geometries collected over a period of nine days. The resulting parameters and BRDFs are similar to those for the

A bound for the Schur index of irreducible representations of finite groups

Energy Technology Data Exchange (ETDEWEB)

Kiselev, D D [M. V. Lomonosov Moscow State University, Faculty of Mechanics and Mathematics, Moscow (Russian Federation)

2013-08-31

We construct an optimal bound for the Schur index of irreducible complex representations of finite groups over the field of rational numbers, when only the prime divisors of the order of the group are known. We study relationships with compatible and universally compatible extensions of number fields. We give a simpler proof of the well-known Berman-Yamada bound for the Schur index over the field Q{sub p}. Bibliography: 7 titles.

On finite groups whose every proper normal subgroup is a union of ...

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

... and |N|(|N| − 1) divides |G| and in particular, |G| is even. Shi [14] proved some deep results about finite group G of order paqb containing a 2- decomposable normal subgroup N. He proved that for such a group |N| = 2, 3, 2 b1 or. 2 a1 +1, where 2b1 −1 is a Mersenne prime and 2a1 +1 is a Fermat prime. Moreover, we have.

On the Steinhaus and Bergman properties for infinite products of finite groups

Czech Academy of Sciences Publication Activity Database

Thomas, S.; Zapletal, Jindřich

2012-01-01

Roč. 4, č. 2 (2012), s. 1250002 ISSN 1793-7442 R&D Projects: GA AV ČR IAA100190902 Institutional research plan: CEZ:AV0Z10190503 Keywords : ultrafilters * products of finite groups * automatic continuity Subject RIV: BA - General Mathematics http://www.worldscientific.com/doi/abs/10.1142/S1793744212500028

Solution of multi-group diffusion equation in x-y-z geometry by finite Fourier transformation

International Nuclear Information System (INIS)

Kobayashi, Keisuke

1975-01-01

The multi-group diffusion equation in three-dimensional x-y-z geometry is solved by finite Fourier transformation. Applying the Fourier transformation to a finite region with constant nuclear cross sections, the fluxes and currents at the material boundaries are obtained in terms of the Fourier series. Truncating the series after the first term, and assuming that the source term is piecewise linear within each mesh box, a set of coupled equations is obtained in the form of three-point equations for each coordinate. These equations can be easily solved by the alternative direction implicit method. Thus a practical procedure is established that could be applied to replace the currently used difference equation. This equation is used to solve the multi-group diffusion equation by means of the source iteration method; and sample calculations for thermal and fast reactors show that the present method yields accurate results with a smaller number of mesh points than the usual finite difference equations. (auth.)

Reflective practice in ESL teacher development groups from practices to principles

CERN Document Server

Farrell, T

2013-01-01

Reflective Practise in ESL Teacher Development Groups  discusses the concept of reflective practice in ESL teachers using data from a 3-year collaborative partnership in which three ESL teachers in Canada explored their professional development through reflective practice.

Fourier transform and the Verlinde formula for the quantum double of a finite group

NARCIS (Netherlands)

Koornwinder, T.H.; Schroers, B.J.; Slingerland, J.K.; Bais, F.A.

1999-01-01

We define a Fourier transform $S$ for the quantum double $D(G)$ of a finite group $G$. Acting on characters of $D(G)$, $S$ and the central ribbon element of $D(G)$ generate a unitary matrix representation of the group $SL(2,Z)$. The characters form a ring over the integers under both the algebra

Special Semigroup Classes Over Some Monoid Constructions and a New Example of a Finitely Presented Monoid with a Non-Finitely Generated Group of Units

Directory of Open Access Journals (Sweden)

Seda OĞUZ ÜNAL

2016-10-01

Full Text Available Abstract. In this paper, necessary and sufficient conditions are studied for Bruck-Reilly and gener- alized Bruck-Reilly ∗-extensions of direct product of k monoids to be regular, unit regular, completely regular and orthodox. Moreover, we give an example of a finitely presented monoid (generalized Bruck-Reilly ∗-extension of Bruck-Reilly extension of a free group with infinite rank, the group of units of which is not finitely generated.2010 Mathematics Subject Classification: 16S15; 20E06; 20E22.Keywords and Phrases: Generalized Bruck-Reilly ∗-extension, finite generation, finite presentability. Özet.  Bu makalede k tane monoidin direkt çarpımının Bruck-Reilly ve genelleştirilmiş Bruck-Reilly *- genişlemelerinin, regüler, terslenebilir regüler, tamamen regüler ve orthodox olabilmesi için gerek ve yeter koşullar çalışılmıştır.  Ayrıca, biz terslenebilir elemanlarının grubu sonlu üreteçli olmayan sonlu sunumlu bir monoid (sonsuz ranklı bir serbest grubun Bruck-Reilly genişlemesinin genelleştirilmiş Bruck-Reilly *-genişlemesi örneği verdik. Anahtar Kelimeler: Genelleştirilmiş Bruck-Reilly *-genişlemesi, sonlu üreteçlilik, sonlu sunumluluk.

A low-memory algorithm for finding short product representations in finite groups

NARCIS (Netherlands)

Bisson, G.; Sutherland, A.V.

2012-01-01

We describe a space-efficient algorithm for solving a generalization of the subset sum problem in a finite group G, using a Pollard-¿ approach. Given an element z and a sequence of elements S, our algorithm attempts to find a subsequence of S whose product in G is equal to z. For a random sequence S

A low-memory algorithm for finding short product representations in finite groups

NARCIS (Netherlands)

Bisson, G.; Sutherland, A.V.

2011-01-01

We describe a space-efficient algorithm for solving a generalization of the subset sum problem in a finite group G, using a Pollard-rho approach. Given an element z and a sequence of elements S, our algorithm attempts to find a subsequence of S whose product in G is equal to z. For a random sequence

Being a reflective teacher——reflection on group management

Institute of Scientific and Technical Information of China (English)

Pan; Lehui

2015-01-01

<正>Introduction According to Pollard and Triggs(1997),reflective teaching is a process through which the capacity to make such professional judgments can be developed and maintained.Then what is a reflective teacher?Reflective teacher is someone who reflects systematically on her practice in a constant attempt to improve

Multivariate stability of force-reflecting teleoperation: Structures of finite and infinite zeros

International Nuclear Information System (INIS)

Daniel, R.W.; McAree, P.R.

2000-01-01

This paper presents a stability analysis of force-position teleoperation under general end-effector contact. The analysis is based on the finite and infinite zero structure of the multivariable root-locus resulting from modulation of the environment stiffness. The starting point is an analysis of the stability of robot force control, motivated by the observation that the human-operator in a force reflection loop acts as a force servo, generating position commands in response to reflected force. Asymptotic root loci properties are used to establish passivity conditions on force feedback to give root locus interpretations of the well-known results that (1) feedback via the inverse joint Jacobian can lead to (kinematic) instability and that (2) passivity is preserved by kinematically proper force feedback through the transpose of the joint angle Jacobian. It is demonstrated that a fully constrained force-position teleoperation loop has an identical infinite zero structure to that of a slave manipulation under kinematically proper force control and that the dominant vibration modes of a force-position loop are fully described by a multivariable analogue of the single-input single-output pseudo-system investigated in a study by Daniel and McAree. Extension of the analysis to cover partial end-effector constraint provides a design tool for teleoperation control and serves to aid selection of teleoperation slate-arms. The paper concludes by giving a passivity condition for multiple-input multiple-output force-position teleoperation for stable contact against all environments

Enhancing medical students' reflectivity in mentoring groups for professional development - a qualitative analysis.

Science.gov (United States)

Lutz, Gabriele; Pankoke, Nina; Goldblatt, Hadass; Hofmann, Marzellus; Zupanic, Michaela

2017-07-14

Professional competence is important in delivering high quality patient care, and it can be enhanced by reflection and reflective discourse e.g. in mentoring groups. However, students are often reluctant though to engage in this discourse. A group mentoring program involving all preclinical students as well as faculty members and co-mentoring clinical students was initiated at Witten-Herdecke University. This study explores both the attitudes of those students towards such a program and factors that might hinder or enhance how students engage in reflective discourse. A qualitative design was applied using semi-structured focus group interviews with preclinical students and semi-structured individual interviews with mentors and co-mentors. The interview data were analyzed using thematic content analysis. Students' attitudes towards reflective discourse on professional challenges were diverse. Some students valued the new program and named positive outcomes regarding several features of professional development. Enriching experiences were described. Others expressed aversive attitudes. Three reasons for these were given: unclear goals and benefits, interpersonal problems within the groups hindering development and intrapersonal issues such as insecurity and traditional views of medical education. Participants mentioned several program setup factors that could enhance how students engage in such groups: explaining the program thoroughly, setting expectations and integrating the reflective discourse in a meaningful way into the curriculum, obliging participation without coercion, developing a sense of security, trust and interest in each other within the groups, randomizing group composition and facilitating group moderators as positive peer and faculty role models and as learning group members. A well-designed and empathetic setup of group mentoring programs can help raise openness towards engaging in meaningful reflective discourse. Reflection on and communication of

Dynamical renormalization group resummation of finite temperature infrared divergences

International Nuclear Information System (INIS)

Boyanovsky, D.; Vega, H.J. de; Boyanovsky, D.; Simionato, M.; Holman, R.; Simionato, M.

1999-01-01

We introduce the method of dynamical renormalization group to study relaxation and damping out of equilibrium directly in real time and apply it to the study of infrared divergences in scalar QED. This method allows a consistent resummation of infrared effects associated with the exchange of quasistatic transverse photons and leads to anomalous logarithmic relaxation of the form e -αampersandhthinsp;Tampersandhthinsp;tampersandhthinsp;ln[t/t 0 ] for hard momentum charged excitations. This is in contrast with the usual quasiparticle interpretation of charged collective excitations at finite temperature in the sense of exponential relaxation of a narrow width resonance for which the width is the imaginary part of the self-energy on shell. In the case of narrow resonances away from thresholds, this approach leads to the usual exponential relaxation. The hard thermal loop resummation program is incorporated consistently into the dynamical renormalization group yielding a picture of relaxation and damping phenomena in a plasma in real time that transcends the conceptual limitations of the quasiparticle picture and other types of resummation schemes. copyright 1999 The American Physical Society

On the Set of the Numbers of Conjugates of Noncyclic Proper Subgroups of Finite Groups

DEFF Research Database (Denmark)

Shi, Jiangtao; Zhang, Cui

2013-01-01

Let G be a finite group and (G) the set of the numbers of conjugates of noncyclic proper subgroups of G. We prove that (1) if |(G)| ≤ 2, then G is solvable, and (2) G is a nonsolvable group with |(G)| = 3 if and only if G≅PSL(2,5) or PSL(2,13) or SL(2,5) or SL(2,13)....

Elastic collisions of classical point particles on a finite frictionless linear track with perfectly reflecting endpoints

Science.gov (United States)

DeLuca, R.

2006-03-01

Repeated elastic collisions of point particles on a finite frictionless linear track with perfectly reflecting endpoints are considered. The problem is analysed by means of an elementary linear algebra approach. It is found that, starting with a state consisting of a projectile particle in motion at constant velocity and a target particle at rest in a fixed known position, the points at which collisions occur on track, when plotted versus progressive numerals, corresponding to the collisions themselves, show periodic patterns for a rather large choice of values of the initial position x(0) and on the mass ratio r. For certain values of these parameters, however, only regular behaviour over a large number of collisions is detected.

On classification of finite groups with four generators, three of which having orders p,p,q (p

International Nuclear Information System (INIS)

Yacoub, K.R.

1984-03-01

Finite groups with two independent generators attracted the attention of authors for several years. The author, having started on such groups in his PhD Thesis in 1953, discussed later on the existence and the structure of finite groups with three generators, one being of arbitrary order and the other two having given orders [Pub. Math. Debrecen, 11, 32-38(1964), 13, 9-16(1966)] and others. Recently, the author started the problem of finite groups with four generators a,b,c and d when b,c and d have the same odd prime order p. It is the object of the present paper to deal with a similar problem when the given orders are p, p and q with p q together with the particular case when m is an element of set containing p,q will be kept to a further discussion. The present paper consists actually of two main parts, the first deals with the case p does not divide q-1 while the second deals with the case p divides q-1. (author)

Evolution of topological features in finite antiferromagnetic Heisenberg chains

International Nuclear Information System (INIS)

Chen Changfeng

2003-01-01

We examine the behavior of nonlocal topological order in finite antiferromagnetic Heisenberg chains using the density matrix renormalization group techniques. We find that chains with even and odd site parity show very different behavior in the topological string order parameter, reflecting interesting interplay of the intrinsic magnetic correlation and the topological term in the chains. Analysis of the calculated string order parameter as a function of the chain length and the topological angle indicates that S=1/2 and S=1 chains show special behavior while all S>1 chains have similar topological structure. This result supports an earlier conjecture on the classification of quantum spin chains based on an analysis of their phase diagrams. Implications of the topological behavior in finite quantum spin chains are discussed

Item Construction Using Reflective, Formative, or Rasch Measurement Models: Implications for Group Work

Science.gov (United States)

Peterson, Christina Hamme; Gischlar, Karen L.; Peterson, N. Andrew

2017-01-01

Measures that accurately capture the phenomenon are critical to research and practice in group work. The vast majority of group-related measures were developed using the reflective measurement model rooted in classical test theory (CTT). Depending on the construct definition and the measure's purpose, the reflective model may not always be the…

Renormalization group and finite size effects in scalar lattice field theories

International Nuclear Information System (INIS)

Bernreuther, W.; Goeckeler, M.

1988-01-01

Binder's phenomenological renormalization group is studied in the context of the O(N)-symmetric euclidean lattice φ 4 theory in dimensions d ≤ 4. By means of the field theoretical formulation of the renormalization group we analyse suitable ratios of Green functions on finite lattices in the limit where the dimensionless lattice length L >> 1 and where the dimensionless bare mass approaches the critical point of the corresponding infinite volume model. If the infrared-stable fixed point which controls this limit is a simple zero of the β-function we are led to formulae which allow the extraction of the critical exponents ν and η. For the gaussian fixed point in four dimensions, discussed as a known example for a multiple zero of the β-function, we derive for these ratios the leading logarithmic corrections to mean field scaling. (orig.)

Developing Reflective Dispositions through Collaborative Knowledge-Building during Small Group Bible Study

Science.gov (United States)

Toh, Tze Keong; Koh, Joyce Hwee Ling; Chai, Ching Sing

2017-01-01

This article explores the use of a constructivist pedagogical approach to cultivate reflective dispositions during small group Bible study. Conducted in a local church Bible class setting (n = 12), the instructional design emulated the reflective thinking process, while adopting collaborative knowledge-building as its pedagogical framework.…

A finite capacity queue with Markovian arrivals and two servers with group services

Directory of Open Access Journals (Sweden)

S. Chakravarthy

1994-01-01

Full Text Available In this paper we consider a finite capacity queuing system in which arrivals are governed by a Markovian arrival process. The system is attended by two exponential servers, who offer services in groups of varying sizes. The service rates may depend on the number of customers in service. Using Markov theory, we study this finite capacity queuing model in detail by obtaining numerically stable expressions for (a the steady-state queue length densities at arrivals and at arbitrary time points; (b the Laplace-Stieltjes transform of the stationary waiting time distribution of an admitted customer at points of arrivals. The stationary waiting time distribution is shown to be of phase type when the interarrival times are of phase type. Efficient algorithmic procedures for computing the steady-state queue length densities and other system performance measures are discussed. A conjecture on the nature of the mean waiting time is proposed. Some illustrative numerical examples are presented.

Modeling Bidirectional Reflectance Distribution Function of One-dimensional Random Rough Surfaces with the Finite Difference Time Domain Method

Directory of Open Access Journals (Sweden)

Min-Jhong Gu

2014-08-01

Full Text Available This article describes the development of a suite of programs that is capable of simulating the radiation properties of a random rough surface (RRS. The fundamental approach involves the generation, by fast Fourier transform (FFT built with rigorous finite difference time domain (FDTD, as the theoretical basis for the simulation of a bidirectional reflectance distribution function (BRDF of the RRS. The results are compared with the measurements and modeling of existing work to verify the feasibility of customized programming. It was found that the results of this study were a better match to the measurement data than those achieved in other modeling work.

The classification of the finite simple groups, number 7 part III, chapters 7-11 the generic case, stages 3b and 4a

CERN Document Server

Gorenstein, Daniel; Solomon, Ronald

2018-01-01

The classification of finite simple groups is a landmark result of modern mathematics. The multipart series of monographs which is being published by the AMS (Volume 40.1-40.7 and future volumes) represents the culmination of a century-long project involving the efforts of scores of mathematicians published in hundreds of journal articles, books, and doctoral theses, totaling an estimated 15,000 pages. This part 7 of the series is the middle of a trilogy (Volume 40.5, Volume 40.7, and forthcoming Volume 40.8) treating the Generic Case, i.e., the identification of the alternating groups of degree at least 13 and most of the finite simple groups of Lie type and Lie rank at least 4. Moreover, Volumes 40.4-40.8 of this series will provide a complete treatment of the simple groups of odd type, i.e., the alternating groups (with two exceptions) and the groups of Lie type defined over a finite field of odd order, as well as some of the sporadic simple groups. In particular, this volume completes the construction, be...

Overgroups of root groups in classical groups

CERN Document Server

Aschbacher, Michael

2016-01-01

The author extends results of McLaughlin and Kantor on overgroups of long root subgroups and long root elements in finite classical groups. In particular he determines the maximal subgroups of this form. He also determines the maximal overgroups of short root subgroups in finite classical groups and the maximal overgroups in finite orthogonal groups of c-root subgroups.

Peer group reflection helps clinical teachers to critically reflect on their teaching.

Science.gov (United States)

Boerboom, Tobias B B; Jaarsma, Debbie; Dolmans, Diana H J M; Scherpbier, Albert J J A; Mastenbroek, Nicole J J M; Van Beukelen, Peter

2011-01-01

Student evaluations can help clinical teachers to reflect on their teaching skills and find ways to improve their teaching. Studies have shown that the mere presentation of student evaluations is not a sufficient incentive for teachers to critically reflect on their teaching. We evaluated and compared the effectiveness of two feedback facilitation strategies that were identical except for a peer reflection meeting. In this study, 54 clinical teachers were randomly assigned to two feedback strategies. In one strategy, a peer reflection was added as an additional step. All teachers completed a questionnaire evaluating the strategy that they had experienced. We analysed the reflection reports and the evaluation questionnaire. Both strategies stimulated teachers to reflect on feedback and formulate alternative actions for their teaching practice. The teachers who had participated in the peer reflection meeting showed deeper critical reflection and more concrete plans to change their teaching. All feedback strategies were considered effective by the majority of the teachers. Strategies with student feedback and self-assessment stimulated reflection on teaching and helped clinical teachers to formulate plans for improvement. A peer reflection meeting seemed to enhance reflection quality. Further research should establish whether it can have lasting effects on teaching quality.

Structure of some relative relation modules of finite p-groups

International Nuclear Information System (INIS)

Yamin, M.

1990-06-01

Let G be a finite p-group generated by (g i , 1 ≤ i ≤ d), G i the cyclic subgroup generated by g i , E the free product of the G i , 1 ≤ i ≤ d, and S the kernel of the natural epimorphism of E onto G. The largest elementary abelian p-quotient S-circumflex = S/S'S p , regarded as an IF p G-module via conjugation in E, is called a relative relation module of G. If d is the minimum number of generaters for G, the author has proved that S-circumflex is nonprojective and indecomposable. The aim of this paper is to give an alternative proof for the indecomposability of S-circumflex; the proof here is more informative as it deals with Loewy structure and generating sets of S-circumflex and other associated modules. (author). 9 refs

Temperature-reflection I

DEFF Research Database (Denmark)

McGady, David A.

2017-01-01

-temperature path integrals for quantum field theories (QFTs) should be T-reflection invariant. Because multi-particle partition functions are equal to Euclidean path integrals for QFTs, we expect them to be T-reflection invariant. Single-particle partition functions though are often not invariant under T......In this paper, we revisit the claim that many partition functions are invariant under reflecting temperatures to negative values (T-reflection). The goal of this paper is to demarcate which partition functions should be invariant under T-reflection, and why. Our main claim is that finite...... that T-reflection is unrelated to time-reversal. Finally, we study the interplay between T-reflection and perturbation theory in the anharmonic harmonic oscillator in quantum mechanics and in Yang-Mills in four-dimensions. This is the first in a series of papers on temperature-reflections....

The classification of p-compact groups for p odd

DEFF Research Database (Denmark)

Andersen, Kasper K. S.; Grodal, Jesper Kragh; Møller, Jesper Michael

2008-01-01

A p-compact group, as defined by Dwyer and Wilkerson, is a purely homotopically defined p-local analog of a compact Lie group. It has long been the hope, and later the conjecture, that these objects should have a classification similar to the classification of compact Lie groups. In this paper we...... groups are uniquely determined as p-compact groups by their Weyl groups seen as finite reflection groups over the p-adic integers. Our approach in fact gives a largely self-contained proof of the entire classification theorem for p odd....

Dense QCD in a Finite Volume

OpenAIRE

Yamamoto, Naoki; Kanazawa, Takuya

2009-01-01

We study the properties of QCD at high baryon density in a finite volume where color superconductivity occurs. We derive exact sum rules for complex eigenvalues of the Dirac operator at finite chemical potential, and show that the Dirac spectrum is directly related to the color superconducting gap $\\Delta$. Also, we find a characteristic signature of color superconductivity: an X-shaped spectrum of partition function zeros in the complex quark mass plane near the origin, reflecting the $Z(2)_...

Observations on finite quantum mechanics

International Nuclear Information System (INIS)

Balian, R.; Itzykson, C.

1986-01-01

We study the canonical transformations of the quantum mechanics on a finite phase space. For simplicity we assume that the configuration variable takes an odd prime number 4 K±1 of distinct values. We show that the canonical group is unitarily implemented. It admits a maximal abelian subgroup of order 4 K, commuting with the finite Fourier transform F, a finite analogue of the harmonic oscillator group. This provides a natural construction of F 1/K and of an orthogonal basis of eigenstates of F [fr

Theory of reflection reflection and transmission of electromagnetic, particle and acoustic waves

CERN Document Server

Lekner, John

2016-01-01

This book deals with the reflection of electromagnetic and particle waves by interfaces. The interfaces can be sharp or diffuse. The topics of the book contain absorption, inverse problems, anisotropy, pulses and finite beams, rough surfaces, matrix methods, numerical methods,  reflection of particle waves and neutron reflection. Exact general results are presented, followed by long wave reflection, variational theory, reflection amplitude equations of the Riccati type, and reflection of short waves. The Second Edition of the Theory of Reflection is an updated and much enlarged revision of the 1987 monograph. There are new chapters on periodically stratified media, ellipsometry, chiral media, neutron reflection and reflection of acoustic waves. The chapter on anisotropy is much extended, with a complete treatment of the reflection and transmission properties of arbitrarily oriented uniaxial crystals. The book gives a systematic and unified treatment reflection and transmission of electromagnetic and particle...

Analysis of Smith-Purcell BWO with end reflections

International Nuclear Information System (INIS)

Kumar, V.; Kim, K.-J.

2006-01-01

We present a one-dimensional time-dependent analysis and simulation of Smith-Purcell (SP) backward wave oscillator (BWO) taking end reflections and attenuation into account. In the linear regime, we obtain an analytic solution and calculate the start current. The dependence of start current on end reflections is studied taking the attenuation due to finite conductivity into account. In this paper, we have set up Maxwell-Lorentz equations for the one-dimensional time-dependent analysis of SP-BWO including end reflection and attenuation due to finite conductivity. We have obtained a solution in the linear regime and extended the analysis to the nonlinear regime by solving the Maxwell-Lorentz equations numerically. Our analysis can be used for detailed optimization of outcoupled power and start current in SP-BWO taking end reflection and attenuation into account.

Enhancing the Effectiveness of Work Groups and Teams: A Reflection.

Science.gov (United States)

Kozlowski, Steve W J

2018-03-01

Teamwork has been at the core of human accomplishment across the millennia, and it was a focus of social psychological inquiry on small group behavior for nearly half a century. However, as organizations world-wide reorganized work around teams over the past two decades, the nature of teamwork and factors influencing it became a central focus of research in organizational psychology and management. In this article, I reflect on the impetus, strategy, key features, and scientific contribution of "Enhancing the Effectiveness of Work Groups and Teams," by Kozlowski and Ilgen, a review monograph published in Psychological Science in the Public Interest in 2006.

Cooperative Learning in Higher Education: Hispanic and Non-Hispanic Undergraduates' Reflections on Group Grades

Science.gov (United States)

Morgan, Bobbette M.

2004-01-01

The purpose of the study is to share reflections from 140 non-Hispanic undergraduate students and 83 Hispanic students who have participated in cooperative written examinations for group grades. Reflections are clustered by themes identified from the students' comments using Van Manen's (1990) hermeneutic phenomonological approach, which is how…

Preserving third year medical students' empathy and enhancing self-reflection using small group "virtual hangout" technology.

Science.gov (United States)

Duke, Pamela; Grosseman, Suely; Novack, Dennis H; Rosenzweig, Steven

2015-01-01

Medical student professionalism education is challenging in scope, purpose, and delivery, particularly in the clinical years when students in large universities are dispersed across multiple clinical sites. We initiated a faculty-facilitated, peer small group course for our third year students, creating virtual classrooms using social networking and online learning management system technologies. The course emphasized narrative self-reflection, group inquiry, and peer support. We conducted this study to analyze the effects of a professionalism course on third year medical students' empathy and self-reflection (two elements of professionalism) and their perceptions about the course. Students completed the Groningen Reflection Ability Scale (GRAS) and the Jefferson Scale of Empathy (JSE) before and after the course and provided anonymous online feedback. The results of the JSE before and after the course demonstrated preservation of empathy rather than its decline. In addition, there was a statistically significant increase in GRAS scores (p < 0.001), suggesting that the sharing of personal narratives may foster reflective ability and reflective practice among third year students. This study supports previous findings showing that students benefit from peer groups and discussion in a safe environment, which may include the use of a virtual group video platform.

Exploratory study of the characteristics of feedback in the reflective dialogue group given to medical students in a clinical clerkship

Directory of Open Access Journals (Sweden)

Chin-Chen Wen

2015-02-01

Full Text Available Purpose: Structured narrative reflective writing combined with guided feedback is an efficient teaching method for enhancing medical students’ reflective capacity. However, what kinds of feedback offered and reflection presented in a reflective group remain unclear. The aim of this study was to investigate the characteristics of feedback in a reflective dialogue group. Methods: Fifth-year medical students on a monthly interval rotation at the pediatric department of a medical center in eastern Taiwan during the 2012 academic year completed their reflective writing regarding patient and family psychosocial issues, and were subsequently debriefed in a 2-h group discussion session to receive feedback from a clinical tutor and peers. Content analysis was conducted to explore the characteristics of feedback and reflection presented in the reflective dialogue. The evaluative questionnaire regarding the benefits of reflection with others was administrated following the group session. Results: Forty students participated in five reflective groups and 108 psychosocial issues were discussed and identified. The tutor played an initiating role in the group discussion by providing six equal feedback types involving exploring new knowledge, initiating advanced discussion, highlighting the issues, and encouraging the students. The students provided eight types of feedback that involved a substantial deep discussion on psychosocial issues and action plans based on the complex interactive ecological network of clinical encounters. Each student attained 1.25 times the depth or breadth of reflection after receiving feedback and experienced the benefits of reflection with others. Conclusion: Through structured narrative reflective writing combined with pluralistic group discussion with a tutor and peers, the medical students had time to think deeply and broadly about psychosocial issues among patients and their family members. Facilitative feedback providing new

Quantum channels irreducibly covariant with respect to the finite group generated by the Weyl operators

Science.gov (United States)

Siudzińska, Katarzyna; Chruściński, Dariusz

2018-03-01

In matrix algebras, we introduce a class of linear maps that are irreducibly covariant with respect to the finite group generated by the Weyl operators. In particular, we analyze the irreducibly covariant quantum channels, that is, the completely positive and trace-preserving linear maps. Interestingly, imposing additional symmetries leads to the so-called generalized Pauli channels, which were recently considered in the context of the non-Markovian quantum evolution. Finally, we provide examples of irreducibly covariant positive but not necessarily completely positive maps.

Free Fermions and the Classical Compact Groups

Science.gov (United States)

Cunden, Fabio Deelan; Mezzadri, Francesco; O'Connell, Neil

2018-06-01

There is a close connection between the ground state of non-interacting fermions in a box with classical (absorbing, reflecting, and periodic) boundary conditions and the eigenvalue statistics of the classical compact groups. The associated determinantal point processes can be extended in two natural directions: (i) we consider the full family of admissible quantum boundary conditions (i.e., self-adjoint extensions) for the Laplacian on a bounded interval, and the corresponding projection correlation kernels; (ii) we construct the grand canonical extensions at finite temperature of the projection kernels, interpolating from Poisson to random matrix eigenvalue statistics. The scaling limits in the bulk and at the edges are studied in a unified framework, and the question of universality is addressed. Whether the finite temperature determinantal processes correspond to the eigenvalue statistics of some matrix models is, a priori, not obvious. We complete the picture by constructing a finite temperature extension of the Haar measure on the classical compact groups. The eigenvalue statistics of the resulting grand canonical matrix models (of random size) corresponds exactly to the grand canonical measure of free fermions with classical boundary conditions.

Free Fermions and the Classical Compact Groups

Science.gov (United States)

Cunden, Fabio Deelan; Mezzadri, Francesco; O'Connell, Neil

2018-04-01

There is a close connection between the ground state of non-interacting fermions in a box with classical (absorbing, reflecting, and periodic) boundary conditions and the eigenvalue statistics of the classical compact groups. The associated determinantal point processes can be extended in two natural directions: (i) we consider the full family of admissible quantum boundary conditions (i.e., self-adjoint extensions) for the Laplacian on a bounded interval, and the corresponding projection correlation kernels; (ii) we construct the grand canonical extensions at finite temperature of the projection kernels, interpolating from Poisson to random matrix eigenvalue statistics. The scaling limits in the bulk and at the edges are studied in a unified framework, and the question of universality is addressed. Whether the finite temperature determinantal processes correspond to the eigenvalue statistics of some matrix models is, a priori, not obvious. We complete the picture by constructing a finite temperature extension of the Haar measure on the classical compact groups. The eigenvalue statistics of the resulting grand canonical matrix models (of random size) corresponds exactly to the grand canonical measure of free fermions with classical boundary conditions.

Reflection groups established by the ASN; Les groupes de reflexion mis en place par l'ASN

Energy Technology Data Exchange (ETDEWEB)

Fournier, M. [ASN, 75 - Paris (France)

2009-07-01

Recent observations about tritium bio-kinetics in aquatic organisms might change our usual consideration about its radio-toxicity. In order to analyse these observations more thoroughly, the French nuclear safety authority (ASN) decided at the end of the year 2007 to create two independent reflection groups gathering scientists, nuclear operators and associations: the group 'tritium impact' has in charge the establishment of a status of the scientific knowledge relative to tritium sanitary impact, while the group 'defense in depth' has in charge the examination of the technical possibilities of tritium reprocessing and the establishment of a knowledge status of its environmental impact. First meetings of both groups took place in May 2008. Abstract only. (J.S.)

Do seedling functional groups reflect ecological strategies of woody plant species in Caatinga?

Directory of Open Access Journals (Sweden)

Tatiane Gomes Calaça Menezes

2017-11-01

Full Text Available ABSTRACT It is assumed that morphological traits of seedlings reflect different strategies in response to environmental conditions. The ecological significance of this has been widely documented in rainforests, where habitat structure and species interactions play an important role in community assembly. However, in seasonally dry ecosystems, where environmental filtering is expected to strongly influence community structure, this relationship is poorly understood. We investigated this relationship between functional groups of seedlings and life history traits and tested whether functional group predicts the ecological strategies employed by woody species to deal with the stressful conditions in seasonally dry ecosystems. Seedling functional groups, life history traits and traits that reflect ecological strategies for occupying seasonally dry environments were described for twenty-six plant species. Seedlings of species from the Caatinga vegetation exhibited a functional profile different from that observed in rainforests ecosystems. Phanerocotylar-epigeal seedlings were the most frequently observed groups, and had the largest range of ecological strategies related to dealing with seasonally dry environments, while phanerocotylar-hypogeal-reserve seedlings exhibited an increase in frequency with seasonality. We discuss these results in relation to those observed in other tropical forests and their ecological significance in seasonally dry environments.

Finite Discrete Gabor Analysis

DEFF Research Database (Denmark)

Søndergaard, Peter Lempel

2007-01-01

frequency bands at certain times. Gabor theory can be formulated for both functions on the real line and for discrete signals of finite length. The two theories are largely the same because many aspects come from the same underlying theory of locally compact Abelian groups. The two types of Gabor systems...... can also be related by sampling and periodization. This thesis extends on this theory by showing new results for window construction. It also provides a discussion of the problems associated to discrete Gabor bases. The sampling and periodization connection is handy because it allows Gabor systems...... on the real line to be well approximated by finite and discrete Gabor frames. This method of approximation is especially attractive because efficient numerical methods exists for doing computations with finite, discrete Gabor systems. This thesis presents new algorithms for the efficient computation of finite...

Construction method of QC-LDPC codes based on multiplicative group of finite field in optical communication

Science.gov (United States)

Huang, Sheng; Ao, Xiang; Li, Yuan-yuan; Zhang, Rui

2016-09-01

In order to meet the needs of high-speed development of optical communication system, a construction method of quasi-cyclic low-density parity-check (QC-LDPC) codes based on multiplicative group of finite field is proposed. The Tanner graph of parity check matrix of the code constructed by this method has no cycle of length 4, and it can make sure that the obtained code can get a good distance property. Simulation results show that when the bit error rate ( BER) is 10-6, in the same simulation environment, the net coding gain ( NCG) of the proposed QC-LDPC(3 780, 3 540) code with the code rate of 93.7% in this paper is improved by 2.18 dB and 1.6 dB respectively compared with those of the RS(255, 239) code in ITU-T G.975 and the LDPC(3 2640, 3 0592) code in ITU-T G.975.1. In addition, the NCG of the proposed QC-LDPC(3 780, 3 540) code is respectively 0.2 dB and 0.4 dB higher compared with those of the SG-QC-LDPC(3 780, 3 540) code based on the two different subgroups in finite field and the AS-QC-LDPC(3 780, 3 540) code based on the two arbitrary sets of a finite field. Thus, the proposed QC-LDPC(3 780, 3 540) code in this paper can be well applied in optical communication systems.

Tagclouds and Group Cognition: Effect of Tagging Support on Students' Reflective Learning in Team Blogs

Science.gov (United States)

Xie, Ying; Lin, Shu-Yuan

2016-01-01

We investigated the effects of supported tagging (a prompting mechanism for students to stop and think about their writing) for team blogging on undergraduate students' reflective learning and the relationship between tagclouds and group cognition. Thirty-nine students were randomly assigned to six groups and blogged for 5 weeks. Three groups were…

Analytic Coarse-Mesh Finite-Difference Method Generalized for Heterogeneous Multidimensional Two-Group Diffusion Calculations

International Nuclear Information System (INIS)

Garcia-Herranz, Nuria; Cabellos, Oscar; Aragones, Jose M.; Ahnert, Carol

2003-01-01

In order to take into account in a more effective and accurate way the intranodal heterogeneities in coarse-mesh finite-difference (CMFD) methods, a new equivalent parameter generation methodology has been developed and tested. This methodology accounts for the dependence of the nodal homogeneized two-group cross sections and nodal coupling factors, with interface flux discontinuity (IFD) factors that account for heterogeneities on the flux-spectrum and burnup intranodal distributions as well as on neighbor effects.The methodology has been implemented in an analytic CMFD method, rigorously obtained for homogeneous nodes with transverse leakage and generalized now for heterogeneous nodes by including IFD heterogeneity factors. When intranodal mesh node heterogeneity vanishes, the heterogeneous solution tends to the analytic homogeneous nodal solution. On the other hand, when intranodal heterogeneity increases, a high accuracy is maintained since the linear and nonlinear feedbacks on equivalent parameters have been shown to be as a very effective way of accounting for heterogeneity effects in two-group multidimensional coarse-mesh diffusion calculations

Solution of the neutron diffusion equation at two groups of energy by method of triangular finite elements

International Nuclear Information System (INIS)

Correia Filho, A.

1981-04-01

The Neutron Diffusion Equation at two groups of energy is solved with the use of the Finite - Element Method with first order triangular elements. The program EFTDN (Triangular Finite Elements on Neutron Diffusion) was developed using the language FORTRAN IV. The discrete formulation of the Diffusion Equation is obtained with the application of the Galerkin's Method. In order to solve the eigenvalue - problem, the Method of the Power is applied and, with the purpose of the convergence of the results, Chebshev's polynomial expressions are applied. On the solution of the systems of equations Gauss' Method is applied, divided in two different parts: triangularization of the matrix of coeficients and retrosubstitution taking in account the sparsity of the system. Several test - problems are solved, among then two P.W.R. type reactors, the ZION-1 with 1300 MWe and the 2D-IAEA - Benchmark. Comparision of results with standard solutions show the validity of application of the EFM and precision of the results. (Author) [pt

Finite groups all of whose minimal subgroups are NE∗ -subgroups

Indian Academy of Sciences (India)

subgroup of G if there exists a subnormal subgroup T of G such that G = HT and H ∩ T is a. NE-subgroup of G. In this article, we investigate the structure of G under the assump- tion that subgroups of prime order are NE∗-subgroups of G. The finite ...

Dense QCD in a Finite Volume

International Nuclear Information System (INIS)

Yamamoto, Naoki; Kanazawa, Takuya

2009-01-01

We study the properties of QCD at high baryon density in a finite volume where color superconductivity occurs. We derive exact sum rules for complex eigenvalues of the Dirac operator at a finite chemical potential, and show that the Dirac spectrum is directly related to the color superconducting gap Δ. Also, we find a characteristic signature of color superconductivity: an X-shaped spectrum of partition function zeros in the complex quark mass plane near the origin, reflecting the Z(2) L xZ(2) R symmetry of the diquark pairing. Our results are universal in the domain Δ -1 π -1 where L is the linear size of the system and m π is the pion mass at high density.

Speed of sound reflects Young's modulus as assessed by microstructural finite element analysis

NARCIS (Netherlands)

Bergh, van den J.P.W.; Lenthe, van G.H.; Hermus, A.R.M.M.; Corstens, F.H.M.; Smals, A.G.H.; Huiskes, H.W.J.

2000-01-01

We analyzed the ability of the quantitative ultrasound (QUS) parameter, speed of sound (SOS), and bone mineral density (BMD), as measured by dual-energy X-ray absorptiometry (DXA), to predict Young's modulus, as assessed by microstructural finite element analysis (muFEA) from microcomputed

Developing critical awareness : the consequences of action and reflection for perceptions of group injustices

NARCIS (Netherlands)

Turner-Zwinkels, Felicity M.; Postmes, Tom; van Zomeren, Martijn

Individuals often cannot address (objective) group injustices until they develop a (subjective) critical awareness of them. In three studies, we tested two potential psychological pathways toward critical awareness: Reflection (deductive, knowledge driven) and action (inductive, action driven)

Mesh-size errors in diffusion-theory calculations using finite-difference and finite-element methods

International Nuclear Information System (INIS)

Baker, A.R.

1982-07-01

A study has been performed of mesh-size errors in diffusion-theory calculations using finite-difference and finite-element methods. As the objective was to illuminate the issues, the study was performed for a 1D slab model of a reactor with one neutron-energy group for which analytical solutions were possible. A computer code SLAB was specially written to perform the finite-difference and finite-element calculations and also to obtain the analytical solutions. The standard finite-difference equations were obtained by starting with an expansion of the neutron current in powers of the mesh size, h, and keeping terms as far as h 2 . It was confirmed that these equations led to the well-known result that the criticality parameter varied with the square of the mesh size. An improved form of the finite-difference equations was obtained by continuing the expansion for the neutron current as far as the term in h 4 . In this case, the critical parameter varied as the fourth power of the mesh size. The finite-element solutions for 2 and 3 nodes per element revealed that the criticality parameter varied as the square and fourth power of the mesh size, respectively. Numerical results are presented for a bare reactive core of uniform composition with 2 zones of different uniform mesh and for a reactive core with an absorptive reflector. (author)

Reflecting reflection in supervision

DEFF Research Database (Denmark)

Lystbæk, Christian Tang

associated with reflection and an exploration of alternative conceptions that view reflection within the context of settings which have a more group- and team-based orientation. Drawing on an action research project on health care supervision, the paper questions whether we should reject earlier views...... of reflection, rehabilitate them in order to capture broader connotations or move to new ways of regarding reflection that are more in keeping with not only reflective but also emotive, normative and formative views on supervision. The paper presents a critical perspective on supervision that challenge...... the current reflective paradigm I supervision and relate this to emotive, normative and formative views supervision. The paper is relevant for Nordic educational research into the supervision and guidance...

The chainable continua are the spaces approximated by finite COTS

Directory of Open Access Journals (Sweden)

Judy A. Kennedy

2001-10-01

Full Text Available We show that the chainable continua (also called snake-like or arc-likecontinua, are precisely the Hausdorff reflections of inverse limits of sequences of finite COTS under maps which are continuous and are separating.

Introduction to Sporadic Groups

Directory of Open Access Journals (Sweden)

Luis J. Boya

2011-01-01

Full Text Available This is an introduction to finite simple groups, in particular sporadic groups, intended for physicists. After a short review of group theory, we enumerate the 1+1+16=18 families of finite simple groups, as an introduction to the sporadic groups. These are described next, in three levels of increasing complexity, plus the six isolated ''pariah'' groups. The (old five Mathieu groups make up the first, smallest order level. The seven groups related to the Leech lattice, including the three Conway groups, constitute the second level. The third and highest level contains the Monster group M, plus seven other related groups. Next a brief mention is made of the remaining six pariah groups, thus completing the 5+7+8+6=26 sporadic groups. The review ends up with a brief discussion of a few of physical applications of finite groups in physics, including a couple of recent examples which use sporadic groups.

Clifford algebra in finite quantum field theories

International Nuclear Information System (INIS)

Moser, M.

1997-12-01

We consider the most general power counting renormalizable and gauge invariant Lagrangean density L invariant with respect to some non-Abelian, compact, and semisimple gauge group G. The particle content of this quantum field theory consists of gauge vector bosons, real scalar bosons, fermions, and ghost fields. We assume that the ultimate grand unified theory needs no cutoff. This yields so-called finiteness conditions, resulting from the demand for finite physical quantities calculated by the bare Lagrangean. In lower loop order, necessary conditions for finiteness are thus vanishing beta functions for dimensionless couplings. The complexity of the finiteness conditions for a general quantum field theory makes the discussion of non-supersymmetric theories rather cumbersome. Recently, the F = 1 class of finite quantum field theories has been proposed embracing all supersymmetric theories. A special type of F = 1 theories proposed turns out to have Yukawa couplings which are equivalent to generators of a Clifford algebra representation. These algebraic structures are remarkable all the more than in the context of a well-known conjecture which states that finiteness is maybe related to global symmetries (such as supersymmetry) of the Lagrangean density. We can prove that supersymmetric theories can never be of this Clifford-type. It turns out that these Clifford algebra representations found recently are a consequence of certain invariances of the finiteness conditions resulting from a vanishing of the renormalization group β-function for the Yukawa couplings. We are able to exclude almost all such Clifford-like theories. (author)

Discrete finite nilpotent Lie analogs: New models for unified gauge field theory

International Nuclear Information System (INIS)

Kornacker, K.

1978-01-01

To each finite dimensional real Lie algebra with integer structure constants there corresponds a countable family of discrete finite nilpotent Lie analogs. Each finite Lie analog maps exponentially onto a finite unipotent group G, and is isomorphic to the Lie algebra of G. Reformulation of quantum field theory in discrete finite form, utilizing nilpotent Lie analogs, should elminate all divergence problems even though some non-Abelian gauge symmetry may not be spontaneously broken. Preliminary results in the new finite representation theory indicate that a natural hierarchy of spontaneously broken symmetries can arise from a single unbroken non-Abelian gauge symmetry, and suggest the possibility of a new unified group theoretic interpretation for hadron colors and flavors

The Weyl approach to the representation theory of reflection equation algebra

International Nuclear Information System (INIS)

Saponov, P A

2004-01-01

The present paper deals with the representation theory of reflection equation algebra, connected to a Hecke type R-matrix. Up to some reasonable additional conditions, the R-matrix is arbitrary (not necessary originating from quantum groups). We suggest a universal method for constructing finite dimensional irreducible representations in the framework of the Weyl approach well known in the representation theory of classical Lie groups and algebras. With this method a series of irreducible modules is constructed. The modules are parametrized by Young diagrams. The spectrum of central elements s k Tr q L k is calculated in the single-row and single-column representations. A rule for the decomposition of the tensor product of modules into a direct sum of irreducible components is also suggested

Toward finite quantum field theories

International Nuclear Information System (INIS)

Rajpoot, S.; Taylor, J.G.

1986-01-01

The properties that make the N=4 super Yang-Mills theory free from ultraviolet divergences are (i) a universal coupling for gauge and matter interactions, (ii) anomaly-free representations, (iii) no charge renormalization, and (iv) if masses are explicitly introduced into the theory, then these are required to satisfy the mass-squared supertrace sum rule Σsub(s=0.1/2)(-1)sup(2s+1)(2s+1)M 2 sub(s)=O. Finite N=2 theories are found to satisfy the above criteria. The missing member in this class of field theories are finite field theories consisting of N=1 superfields. These theories are discussed in the light of the above finiteness properties. In particular, the representations of all simple classical groups satisfying the anomaly-free and no-charge renormalization conditions for finite N=1 field theories are discussed. A consequence of these restrictions on the allowed representations is that an N=1 finite SU(5)-based model of strong and electroweak interactions can contain at most five conventional families of quarks and leptons, a constraint almost compatible with the one deduced from cosmological arguments. (author)

Conversion of optical wave polarizations in 1D finite anisotropic photonic crystal

International Nuclear Information System (INIS)

Ouchani, N.; Nougaoui, N.; Daoudi, A.; Bria, D.

2006-07-01

We show that by using one dimensional anisotropic photonic structures, it is possible to realize optical wave polarization conversion by transmission or by reflection. Thus a single incident S(P) polarized plane wave can produce a single reflected P(S) polarized wave and a single transmitted P(S) polarized wave. This polarization conversion property can be fulfilled with a simple finite superlattice constituted by anisotropic dielectric materials. We discuss the appropriate choices of the material and geometrical properties to realize such structures. The transmission and reflection coefficients are discussed in relation with the dispersion curves of the finite structure embedded between two isotropic substrates. Both transmission and reflection coefficients are calculated in the framework of Green's function method. The amplitude and the polarization characteristics of reflected and transmitted waves are determined as function of frequency ω , and wave vector k parallel ( parallel to the interface) and the orientations of the principal axes of the layers constituting the SL. Moreover, this structure exhibits a coupling between S and P waves that does not exist in SL composed only of isotropic materials. Specific applications of these results are given for a superlattice consisting of alternating biaxial anisotropic layers NaNO 2 /SbSi sandwiched between two identical semi-infinite isotropic media. (author)

Accuracy of finite-difference modeling of seismic waves : Simulation versus laboratory measurements

Science.gov (United States)

Arntsen, B.

2017-12-01

The finite-difference technique for numerical modeling of seismic waves is still important and for some areas extensively used.For exploration purposes is finite-difference simulation at the core of both traditional imaging techniques such as reverse-time migration and more elaborate Full-Waveform Inversion techniques.The accuracy and fidelity of finite-difference simulation of seismic waves are hard to quantify and meaningfully error analysis is really onlyeasily available for simplistic media. A possible alternative to theoretical error analysis is provided by comparing finite-difference simulated data with laboratory data created using a scale model. The advantage of this approach is the accurate knowledge of the model, within measurement precision, and the location of sources and receivers.We use a model made of PVC immersed in water and containing horizontal and tilted interfaces together with several spherical objects to generateultrasonic pressure reflection measurements. The physical dimensions of the model is of the order of a meter, which after scaling represents a model with dimensions of the order of 10 kilometer and frequencies in the range of one to thirty hertz.We find that for plane horizontal interfaces the laboratory data can be reproduced by the finite-difference scheme with relatively small error, but for steeply tilted interfaces the error increases. For spherical interfaces the discrepancy between laboratory data and simulated data is sometimes much more severe, to the extent that it is not possible to simulate reflections from parts of highly curved bodies. The results are important in view of the fact that finite-difference modeling is often at the core of imaging and inversion algorithms tackling complicatedgeological areas with highly curved interfaces.

Testing Linear Temporal Logic Formulae on Finite Execution Traces

Science.gov (United States)

Havelund, Klaus; Rosu, Grigore; Norvig, Peter (Technical Monitor)

2001-01-01

We present an algorithm for efficiently testing Linear Temporal Logic (LTL) formulae on finite execution traces. The standard models of LTL are infinite traces, reflecting the behavior of reactive and concurrent systems which conceptually may be continuously alive. In most past applications of LTL. theorem provers and model checkers have been used to formally prove that down-scaled models satisfy such LTL specifications. Our goal is instead to use LTL for up-scaled testing of real software applications. Such tests correspond to analyzing the conformance of finite traces against LTL formulae. We first describe what it means for a finite trace to satisfy an LTL property. We then suggest an optimized algorithm based on transforming LTL formulae. The work is done using the Maude rewriting system. which turns out to provide a perfect notation and an efficient rewriting engine for performing these experiments.

Normal forms of invariant vector fields under a finite group action

International Nuclear Information System (INIS)

Sanchez Bringas, F.

1992-07-01

Let Γ be a finite subgroup of GL(n,C). This subgroup acts on the space of germs of holomorphic vector fields vanishing at the origin in C n . We prove a theorem of invariant conjugation to a normal form and linearization for the subspace of invariant elements and we give a description of these normal forms in dimension n=2. (author)

Finite N=1 SUSY gauge field theories

International Nuclear Information System (INIS)

Kazakov, D.I.

1986-01-01

The authors give a detailed description of the method to construct finite N=1 SUSY gauge field theories in the framework of N=1 superfields within dimensional regularization. The finiteness of all Green functions is based on supersymmetry and gauge invariance and is achieved by a proper choice of matter content of the theory and Yukawa couplings in the form Y i =f i (ε)g, where g is the gauge coupling, and the function f i (ε) is regular at ε=0 and is calculated in perturbation theory. Necessary and sufficient conditions for finiteness are determined already in the one-loop approximation. The correspondence with an earlier proposed approach to construct finite theories based on aigenvalue solutions of renormalization-group equations is established

Finite element reliability analysis of fatigue life

International Nuclear Information System (INIS)

Harkness, H.H.; Belytschko, T.; Liu, W.K.

1992-01-01

Fatigue reliability is addressed by the first-order reliability method combined with a finite element method. Two-dimensional finite element models of components with cracks in mode I are considered with crack growth treated by the Paris law. Probability density functions of the variables affecting fatigue are proposed to reflect a setting where nondestructive evaluation is used, and the Rosenblatt transformation is employed to treat non-Gaussian random variables. Comparisons of the first-order reliability results and Monte Carlo simulations suggest that the accuracy of the first-order reliability method is quite good in this setting. Results show that the upper portion of the initial crack length probability density function is crucial to reliability, which suggests that if nondestructive evaluation is used, the probability of detection curve plays a key role in reliability. (orig.)

On beam shaping of the field radiated by a line source coupled to finite or infinite photonic crystals.

Science.gov (United States)

Ceccuzzi, Silvio; Jandieri, Vakhtang; Baccarelli, Paolo; Ponti, Cristina; Schettini, Giuseppe

2016-04-01

Comparison of the beam-shaping effect of a field radiated by a line source, when an ideal infinite structure constituted by two photonic crystals and an actual finite one are considered, has been carried out by means of two different methods. The lattice sums technique combined with the generalized reflection matrix method is used to rigorously investigate the radiation from the infinite photonic crystals, whereas radiation from crystals composed of a finite number of rods along the layers is analyzed using the cylindrical-wave approach. A directive radiation is observed with the line source embedded in the structure. With an increased separation distance between the crystals, a significant edge diffraction appears that provides the main radiation mechanism in the finite layout. Suitable absorbers are implemented to reduce the above-mentioned diffraction and the reflections at the boundaries, thus obtaining good agreement between radiation patterns of a localized line source coupled to finite and infinite photonic crystals, when the number of periods of the finite structure is properly chosen.

Gate-voltage control of equal-spin Andreev reflection in half-metal/semiconductor/superconductor junctions

Energy Technology Data Exchange (ETDEWEB)

Wu, Xiuqiang, E-mail: xianqiangzhe@126.com [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China); Meng, Hao, E-mail: menghao1982@shu.edu.cn [School of Physics and Telecommunication Engineering, Shanxi University of Technology, Hanzhong 723001 (China)

2016-04-22

With the Blonder–Tinkham–Klapwijk (BTK) approach, we investigate conductance spectrum in Ferromagnet/Semiconductor/Superconductor (FM/Sm/SC) double tunnel junctions where strong Rashba spin–orbit interaction (RSOI) is taken into account in semiconductors. For the half-metal limit, we find that the in-gap conductance becomes finite except at zero voltage when inserting a ferromagnetic insulator (FI) at the Sm/SC interface, which means that the appearance of a long-range triplet states in the half-metal. This is because of the emergence of the unconventional equal-spin Andreev reflection (ESAR). When the FI locates at the FM/Sm interface, however, we find the vanishing in-gap conductance due to the absence of the ESAR. Moreover, the non-zero in-gap conductance shows a nonmonotonic dependence on RSOI which can be controlled by applying an external gate voltage. Our results can be used to generate and manipulate the long-range spin triplet correlation in the nascent field of superconducting spintronics. - Highlights: • We study the equal-spin Andreev reflection in half-metal/semiconductor/superconductor (HM/Sm/SC) junctions. • The equal-spin Andreev reflection appearance when inserting a ferromagnetic insulator at the Sm/SC interface. • The finite in-gap conductance is attributed to the emergence of the equal-spin Andreev reflection. • The finite in-gap conductance shows a nonmonotonic dependence on Rashba spin–orbit interaction. • The finite in-gap conductance can be controlled by applying an external gate voltage.

Reflection of sound from finite-size plane and curved surfaces

DEFF Research Database (Denmark)

Rindel, Jens Holger

2005-01-01

of a reflector array can improve if the size of the panels is decreased. The same design frequency applies to a single reflector and a reflector array, but with different meaning; in the latter case the design frequency is the upper limit for useful reflections. This design rule was first used...

On some homological functors of Bieberbach group of dimension four with dihedral point group of order eight

Science.gov (United States)

Mohammad, Siti Afiqah; Ali, Nor Muhainiah Mohd; Sarmin, Nor Haniza; Idrus, Nor'ashiqin Mohd; Masri, Rohaidah

2014-06-01

A Bieberbach group is a torsion free crystallographic group, which is an extension of a free abelian group of finite rank by a finite point group, while homological functors of a group include nonabelian tensor square, exterior square and Schur Multiplier. In this paper, some homological functors of a Bieberbach group of dimension four with dihedral point group of order eight are computed.

New strings for old Veneziano amplitudes. II. Group-theoretic treatment

Science.gov (United States)

Kholodenko, A. L.

2006-09-01

In this part of our four parts work we use theory of polynomial invariants of finite pseudo-reflection groups in order to reconstruct both the Veneziano and Veneziano-like (tachyon-free) amplitudes and the generating function reproducing these amplitudes. We demonstrate that such generating function and amplitudes associated with it can be recovered with help of finite dimensional exactly solvableN=2 supersymmetric quantum mechanical model known earlier from works of Witten, Stone and others. Using the Lefschetz isomorphism theorem we replace traditional supersymmetric calculations by the group-theoretic thus solving the Veneziano model exactly using standard methods of representation theory. Mathematical correctness of our arguments relies on important theorems by Shepard and Todd, Serre and Solomon proven respectively in the early 50s and 60s and documented in the monograph by Bourbaki. Based on these theorems, we explain why the developed formalism leaves all known results of conformal field theories unchanged. We also explain why these theorems impose stringent requirements connecting analytical properties of scattering amplitudes with symmetries of space-time in which such amplitudes act.

Pomarning-eddington approximation for time-dependent radiation transfer in finite slab media

International Nuclear Information System (INIS)

El-Wakil, S.A.; Degheidy, A.R.; Sallah, M.

2005-01-01

The time-dependent monoenergetic radiation transfer equation with linear anisotropic scattering is proposed. Pomraning-Eddington approximation is used to calculate the radiation intensity in finite plane-parallel media. Numerical results are done for the isotropic media. Shielding calculations are shown for reflectivity and transmissivity at different times. The medium is assumed to have specular-reflecting boundaries. Two different weight functions are introduced to force the boundary conditions to be fulfilled

Cook-Levin Theorem Algorithmic-Reducibility/Completeness = Wilson Renormalization-(Semi)-Group Fixed-Points; ``Noise''-Induced Phase-Transitions (NITs) to Accelerate Algorithmics (``NIT-Picking'') REPLACING CRUTCHES!!!: Models: Turing-machine, finite-state-models, finite-automata

Science.gov (United States)

Young, Frederic; Siegel, Edward

Cook-Levin theorem theorem algorithmic computational-complexity(C-C) algorithmic-equivalence reducibility/completeness equivalence to renormalization-(semi)-group phase-transitions critical-phenomena statistical-physics universality-classes fixed-points, is exploited via Siegel FUZZYICS =CATEGORYICS = ANALOGYICS =PRAGMATYICS/CATEGORY-SEMANTICS ONTOLOGY COGNITION ANALYTICS-Aristotle ``square-of-opposition'' tabular list-format truth-table matrix analytics predicts and implements ''noise''-induced phase-transitions (NITs) to accelerate versus to decelerate Harel [Algorithmics (1987)]-Sipser[Intro.Thy. Computation(`97)] algorithmic C-C: ''NIT-picking''(!!!), to optimize optimization-problems optimally(OOPO). Versus iso-''noise'' power-spectrum quantitative-only amplitude/magnitude-only variation stochastic-resonance, ''NIT-picking'' is ''noise'' power-spectrum QUALitative-type variation via quantitative critical-exponents variation. Computer-''science''/SEANCE algorithmic C-C models: Turing-machine, finite-state-models, finite-automata,..., discrete-maths graph-theory equivalence to physics Feynman-diagrams are identified as early-days once-workable valid but limiting IMPEDING CRUTCHES(!!!), ONLY IMPEDE latter-days new-insights!!!

Avoiding Pitfalls and Realising Opportunities: Reflecting on Issues of Sampling and Recruitment for Online Focus Groups.

Science.gov (United States)

Boydell, Nicola; Fergie, Gillian; McDaid, Lisa; Hilton, Shona

2014-02-01

The increasing prominence of the Internet in everyday life has prompted methodological innovations in qualitative research, particularly the adaptation of established methods of data collection for use online. The alternative online context brings with it both opportunities and challenges. To date the literature on online focus groups has focused mainly on the suitability of the method for qualitative data collection, and the development of approaches to facilitation that maximise interaction. By reflecting on our experiences of designing and attempting to recruit participants to online focus groups for two exploratory research projects, we aim to contribute some novel reflections around the less articulated issues of sampling and recruitment for online focus groups. In particular, we highlight potentially problematic issues around offline recruitment for an online method of data collection; the potential of using social media for recruitment; and the uncertainties around offering incentives in online recruitment, issues which have received little attention in the growing literature around online focus groups. More broadly, we recommend continued examination of online social practices and the social media environment to develop appropriate and timely online recruitment strategies and suggest further areas for future research and innovation.

Avoiding Pitfalls and Realising Opportunities: Reflecting on Issues of Sampling and Recruitment for Online Focus Groups

Directory of Open Access Journals (Sweden)

Nicola Boydell MSc

2014-02-01

Full Text Available The increasing prominence of the Internet in everyday life has prompted methodological innovations in qualitative research, particularly the adaptation of established methods of data collection for use online. The alternative online context brings with it both opportunities and challenges. To date the literature on online focus groups has focused mainly on the suitability of the method for qualitative data collection, and the development of approaches to facilitation that maximise interaction. By reflecting on our experiences of designing and attempting to recruit participants to online focus groups for two exploratory research projects, we aim to contribute some novel reflections around the less articulated issues of sampling and recruitment for online focus groups. In particular, we highlight potentially problematic issues around offline recruitment for an online method of data collection; the potential of using social media for recruitment; and the uncertainties around offering incentives in online recruitment, issues which have received little attention in the growing literature around online focus groups. More broadly, we recommend continued examination of online social practices and the social media environment to develop appropriate and timely online recruitment strategies and suggest further areas for future research and innovation.

Elastodynamic models for extending GTD to penumbra and finite size flaws

International Nuclear Information System (INIS)

Djakou, A Kamta; Darmon, M; Potel, C

2016-01-01

The scattering of elastic waves from an obstacle is of great interest in ultrasonic Non Destructive Evaluation (NDE). There exist two main scattering phenomena: specular reflection and diffraction. This paper is especially focused on possible improvements of the Geometrical Theory of Diffraction (GTD), one classical method used for modelling diffraction from scatterer edges. GTD notably presents two important drawbacks: it is theoretically valid for a canonical infinite edge and not for a finite one and presents discontinuities around the direction of specular reflection. In order to address the first drawback, a 3D hybrid method using both GTD and Huygens secondary sources has been developed to deal with finite flaws. ITD (Incremental Theory of Diffraction), a method developed in electromagnetism, has also been developed in elastodynamics to deal with small flaws. Experimental validation of these methods has been performed. As to the second drawback, a GTD uniform correction, the UTD (Uniform Theory of Diffraction) has been developed in the view of designing a generic model able to correctly simulate both specular reflection and diffraction. A comparison has been done between UTD numerical results and UAT (Uniform Asymptotic Theory of Diffraction) which is another uniform solution of GTD. (paper)

Uniqueness in inverse elastic scattering with finitely many incident waves

International Nuclear Information System (INIS)

Elschner, Johannes; Yamamoto, Masahiro

2009-01-01

We consider the third and fourth exterior boundary value problems of linear isotropic elasticity and present uniqueness results for the corresponding inverse scattering problems with polyhedral-type obstacles and a finite number of incident plane elastic waves. Our approach is based on a reflection principle for the Navier equation. (orig.)

Methodological Reflections on the Use of Asynchronous Online Focus Groups in Health Research

Directory of Open Access Journals (Sweden)

Sarah Williams PhD

2012-09-01

Full Text Available The Internet is increasingly used as a tool in qualitative research. In particular, asynchronous online focus groups are used when factors such as cost, time, or access to participants can make conducting face-to-face research difficult. In this article we consider key methodological issues involved in using asynchronous online focus groups to explore experiences of health and illness. The written nature of Internet communication, the lack of physical presence, and the asynchronous, longitudinal aspects enable participants who might not normally contribute to research studies to reflect on their personal stories before disclosing them to the researcher. Implications for study design, recruitment strategies, and ethics should be considered when deciding whether to use this method.

Medical Students' Empathy for Vulnerable Groups: Results From a Survey and Reflective Writing Assignment.

Science.gov (United States)

Wellbery, Caroline; Saunders, Pamela A; Kureshi, Sarah; Visconti, Adam

2017-12-01

As medical education curricula increasingly acknowledge the contributions of the social determinants of health to individual health, new methods of engaging students in the care of vulnerable groups are needed. Empathy is one way to connect students with patients, but little is known about how to nurture students' empathy on behalf of populations. This study examined the relationship between individual and social empathy as groundwork for cultivating students' empathy for vulnerable groups. In 2014-2015, first-year medical students completed the Social Empathy Index at the start and end of a two-semester population health course, and they completed a reflective writing assignment exploring the challenges of caring for vulnerable patients. Pre- and posttest mean survey scores were compared, and reflective writing assignments were analyzed for themes concerning social empathy. Data from 130 students were analyzed. Scores for the contextual understanding of systemic barriers domain increased significantly. There was a trend toward increased cumulative social empathy scores that did not reach statistical significance. Students' essays revealed three themes relating to individual empathy as the foundation for social empathy; civic and moral obligations; and the role of institutional practices in caring for vulnerable groups. This study extends understanding of empathy beyond care for the individual to include care for vulnerable groups. Thus, social empathy may function as a valuable concept in developing curricula to support students' commitment to care for the underserved. Educators first need to address the many barriers students cited that impede both individual and social empathy.

Construction d'enquête et définition des groupes sociaux

Directory of Open Access Journals (Sweden)

Cyprien Tasset

2010-09-01

Full Text Available Dans ce texte, nous abordons le livre de Jerrold Seigel à travers le problème du rapport entre la construction de l'objet et celle de l'enquête. En effet, comment peut-on étudier méthodiquement un groupe tel que la bohème littéraire ? À partir d'une discussion quant à la pertinence, dans ce cas, de recourir à la méthode de la définition provisoire, nous nous interrogerons sur le genre de collectif constitué, au xixe siècle, par la bohème littéraire. À l'heure où le travail symbolique accompli au xixe siècle pour faire de la bohème un lieu social largement visible est réactivé par plusieurs entrepreneurs de groupes sociaux, cette réflexion méthodologique aura également l'intérêt de porter, indirectement, sur des efforts de regroupement contemporains.Inquiry’s construction and definition of social grouping. Reflexions from Bohemian Paris by Jerrold SeigelIn this paper, we study Jerrold Seigel's book through the prism of the issue of the relation between the way the author constructs his object and that of the inquiry. As a matter of fact, how is it possible to study methodologically a group such as literary bohemia ? After discussing the relevance, in this case, of the provisional definition method, we will ask ourselves which kind of collective literary bohemia constituted in the 19th century. At a time when several entrepreneurs of social grouping are re-activating the symbolical work carried in the 19th century to turn bohemia into a visible social area, the interest of such methodological exploration also lies in its bearing, indirectly, on contemporary grouping efforts.Construcción de la investigación y definición de grupo social. Reflexión a partir deBohemian Paris de Jerrold SeigelEn este artículo, abordamos el libro de Jerrold Seigel enfocando la relación entre la manera cómo el autor construye su objeto y la manera cómo dirige su investigación. ¿De hecho, de qué modo se puede estudiar con m

Modelling of ground penetrating radar data in stratified media using the reflectivity technique

International Nuclear Information System (INIS)

Sena, Armando R; Sen, Mrinal K; Stoffa, Paul L

2008-01-01

Horizontally layered media are often encountered in shallow exploration geophysics. Ground penetrating radar (GPR) data in these environments can be modelled by techniques that are more efficient than finite difference (FD) or finite element (FE) schemes because the lateral homogeneity of the media allows us to reduce the dependence on the horizontal spatial variables through Fourier transforms on these coordinates. We adapt and implement the invariant embedding or reflectivity technique used to model elastic waves in layered media to model GPR data. The results obtained with the reflectivity and FDTD modelling techniques are in excellent agreement and the effects of the air–soil interface on the radiation pattern are correctly taken into account by the reflectivity technique. Comparison with real wide-angle GPR data shows that the reflectivity technique can satisfactorily reproduce the real GPR data. These results and the computationally efficient characteristics of the reflectivity technique (compared to FD or FE) demonstrate its usefulness in interpretation and possible model-based inversion schemes of GPR data in stratified media

Finite element analysis of multilayer coextrusion.

Energy Technology Data Exchange (ETDEWEB)

Hopkins, Matthew Morgan; Schunk, Peter Randall; Baer, Thomas A. (Proctor & Gamble Company, West Chester, OH); Mrozek, Randy A. (Army Research Laboratory, Adelphi, MD); Lenhart, Joseph Ludlow (Army Research Laboratory, Adelphi, MD); Rao, Rekha Ranjana; Collins, Robert (Oak Ridge National Laboratory); Mondy, Lisa Ann

2011-09-01

Multilayer coextrusion has become a popular commercial process for producing complex polymeric products from soda bottles to reflective coatings. A numerical model of a multilayer coextrusion process is developed based on a finite element discretization and two different free-surface methods, an arbitrary-Lagrangian-Eulerian (ALE) moving mesh implementation and an Eulerian level set method, to understand the moving boundary problem associated with the polymer-polymer interface. The goal of this work is to have a numerical capability suitable for optimizing and troubleshooting the coextrusion process, circumventing flow instabilities such as ribbing and barring, and reducing variability in layer thickness. Though these instabilities can be both viscous and elastic in nature, for this work a generalized Newtonian description of the fluid is used. Models of varying degrees of complexity are investigated including stability analysis and direct three-dimensional finite element free surface approaches. The results of this work show how critical modeling can be to reduce build test cycles, improve material choices, and guide mold design.

Quantization and representation theory of finite W algebras

International Nuclear Information System (INIS)

Boer, J. de; Tjin, T.

1993-01-01

In this paper we study the finitely generated algebras underlying W algebras. These so called 'finite W algebras' are constructed as Poisson reductions of Kirillov Poisson structures on simple Lie algebras. The inequivalent reductions are labeled by the inequivalent embeddings of sl 2 into the simple Lie algebra in question. For arbitrary embeddings a coordinate free formula for the reduced Poisson structure is derived. We also prove that any finite W algebra can be embedded into the Kirillov Poisson algebra of a (semi)simple Lie algebra (generalized Miura map). Furthermore it is shown that generalized finite Toda systems are reductions of a system describing a free particle moving on a group manifold and that they have finite W symmetry. In the second part we BRST quantize the finite W algebras. The BRST cohomoloy is calculated using a spectral sequence (which is different from the one used by Feigin and Frenkel). This allows us to quantize all finite W algebras in one stroke. Examples are given. In the last part of the paper we study the representation theory of finite W algebras. It is shown, using a quantum inversion of the generalized Miura transformation, that the representations of finite W algebras can be constructed from the representations of a certain Lie subalgebra of the original simple Lie algebra. As a byproduct of this we are able to construct the Fock realizations of arbitrary finite W algebras. (orig.)

Using a Smartphone App and Coaching Group Sessions to Promote Residents' Reflection in the Workplace.

Science.gov (United States)

Könings, Karen D; van Berlo, Jean; Koopmans, Richard; Hoogland, Henk; Spanjers, Ingrid A E; ten Haaf, Jeroen A; van der Vleuten, Cees P M; van Merriënboer, Jeroen J G

2016-03-01

Reflecting on workplace-based experiences is necessary for professional development. However, residents need support to raise their awareness of valuable moments for learning and to thoughtfully analyze those learning moments afterwards. From October to December 2012, the authors held a multidisciplinary six-week postgraduate training module focused on general competencies. Residents were randomly assigned to one of four conditions with varying degrees of reflection support; they were offered (1) a smartphone app, (2) coaching group sessions, (3) a combination of both, or (4) neither type of support. The app allowed participants to capture in real time learning moments as a text note, audio recording, picture, or video. Coaching sessions held every two weeks aimed to deepen participants' reflection on captured learning moments. Questionnaire responses and reflection data were compared between conditions to assess the effects of the app and coaching sessions on intensity and frequency of reflection. Sixty-four residents participated. App users reflected more often, captured more learning moments, and reported greater learning progress than nonapp users. Participants who attended coaching sessions were more alert to learning moments and pursued more follow-up learning activities to improve on the general competencies. Those who received both types of support were most alert to these learning moments. A simple mobile app for capturing learning moments shows promise as a tool to support workplace-based learning, especially when combined with coaching sessions. Future research should evaluate these tools on a broader scale and in conjunction with residents' and students' personal digital portfolios.

Self-reflection, gender and science achievement

Science.gov (United States)

Shoop, Kathleen A.

Drawing on socio-cognitive learning theory, this study compared achievement scores of 134 male and female high school biology students randomly assigned to groups which either used self-reflection, used self-reflection and received feedback, or did not self-reflect. Following a pretest, the teacher provided self-reflection strategy instruction to students in the two intervention groups and then subsequently provided in-class self-reflection time for these groups. The posttest concluded the unit; the retention measure was five weeks later. A quasi-experimental 3 x 3 x 2 (time x intervention x gender) factorial repeated-measures control group design was used for this study; a repeated measures ANOVA and several one-way ANOVA's were used to answer the research questions. Results from the repeated-measures ANOVA revealed significant results for Time and Time x Intervention, with the reflection group demonstrating significantly lower gains from pretest to posttest than the other two groups. The ANOVA examining differences between those who reflected and those who reflected and received feedback provided significant results with similar results for the difference between the control group and the reflection group. For teachers and students this study provides several areas of practical significance. Primarily, teachers may find lower student achievement if students regularly self-reflect but do not receive feedback for their reflection.

The effect of reflections on the performance of an acoustic energy transfer system

NARCIS (Netherlands)

Roes, M.G.L.; Hendrix, M.A.M.; Duarte, J.L.

2012-01-01

Abstract—The performance of an acoustic energy transfer (AET) system, defined as the ratio of electrical output to input power, is affected to a large extent by reflections. Their effect is examined in this paper. A finite element model is created to model reflections in a typical AET system, of

Finite and profinite quantum systems

CERN Document Server

Vourdas, Apostolos

2017-01-01

This monograph provides an introduction to finite quantum systems, a field at the interface between quantum information and number theory, with applications in quantum computation and condensed matter physics. The first major part of this monograph studies the so-called `qubits' and `qudits', systems with periodic finite lattice as position space. It also discusses the so-called mutually unbiased bases, which have applications in quantum information and quantum cryptography. Quantum logic and its applications to quantum gates is also studied. The second part studies finite quantum systems, where the position takes values in a Galois field. This combines quantum mechanics with Galois theory. The third part extends the discussion to quantum systems with variables in profinite groups, considering the limit where the dimension of the system becomes very large. It uses the concepts of inverse and direct limit and studies quantum mechanics on p-adic numbers. Applications of the formalism include quantum optics and ...

3D-Printed Broadband Dielectric Tube Terahertz Waveguide with Anti-Reflection Structure

Science.gov (United States)

Vogt, Dominik Walter; Leonhardt, Rainer

2016-11-01

We demonstrate broadband, low loss, and close-to-zero dispersion guidance of terahertz (THz) radiation in a dielectric tube with an anti-reflection structure (AR-tube waveguide) in the frequency range from 0.2 to 1.0 THz. The anti-reflection structure (ARS) consists of close-packed cones in a hexagonal lattice arranged on the outer surface of the tube cladding. The feature size of the ARS is in the order of the wavelength between 0.2 and 1.0 THz. The waveguides are fabricated with the versatile and cost efficient 3D-printing method. Terahertz time-domain spectroscopy (THz-TDS) measurements as well as 3D finite-difference time-domain simulations (FDTD) are performed to extensively characterize the AR-tube waveguides. Spectrograms, attenuation spectra, effective phase refractive indices, and the group-velocity dispersion parameters β 2 of the AR-tube waveguides are presented. Both the experimental and numerical results confirm the extended bandwidth and smaller group-velocity dispersion of the AR-tube waveguide compared to a low loss plain dielectric tube THz waveguide. The AR-tube waveguide prototypes show an attenuation spectrum close to the theoretical limit given by the infinite cladding tube waveguide.

Reflection, radiation, and interference near the black hole horizon

International Nuclear Information System (INIS)

Kuchiev, M.Yu.

2004-01-01

The event horizon of black holes is capable of reflection: there is a finite probability for any particle that approaches the horizon to bounce back. The albedo of the horizon depends on the black hole temperature and the energy of the incoming particle. The reflection shares its physical origins with the Hawking process of radiation; both of them arise as consequences of the mixing of the incoming and outgoing waves that takes place due to quantum processes on the event horizon

On the reflection of solitons of the cubic nonlinear Schrödinger equation

KAUST Repository

Katsaounis, Theodoros

2016-07-05

In this paper, we perform a numerical study on the interesting phenomenon of soliton reflection of solid walls. We consider the 2D cubic nonlinear Schrödinger equation as the underlying mathematical model, and we use an implicit-explicit type Crank-Nicolson finite element scheme for its numerical solution. After verifying the perfect reflection of the solitons on a vertical wall, we present the imperfect reflection of a dark soliton on a diagonal wall.

Observing Engineering Student Teams from the Organization Behavior Perspective Using Linguistic Analysis of Student Reflections and Focus Group Interviews

Science.gov (United States)

Kearney, Kerri S.; Damron, Rebecca; Sohoni, Sohum

2015-01-01

This paper investigates group/team development in computer engineering courses at a University in the Central USA from the perspective of organization behavior theory, specifically Tuckman's model of the stages of group development. The investigation, conducted through linguistic analysis of student reflection essays, and through focus group…

Exploring Forms of Triangulation to Facilitate Collaborative Research Practice: Reflections From a Multidisciplinary Research Group

Directory of Open Access Journals (Sweden)

Tarja Tiainen

2006-10-01

Full Text Available This article contains critical reflections of a multidisciplinary research group studying the human and technological dynamics around some newly offered electronic services in a specific rural area of Finland. For their research, the group adopted ethnography. On facing the challenges of doing ethnographic research in a multidisciplinary setting, the group evolved its own breed of research practice based on multiple forms of triangulation. This implied the use of multiple data sources, methods, theories, and researchers, in different combinations. One of the outcomes of the work is a model for collaborative research. It highlights, among others, the importance of creating a climate for collaboration within the research group and following a process of individual and collaborative writing to achieve the potential benefits of such research. The article also identifies a set of remaining challenges relevant to collaborative research.

A cut locus for finite graphs and the farthest point mapping

DEFF Research Database (Denmark)

Maddaloni, Alessandro; Zamfirescu, Carol T.

2016-01-01

We reflect upon an analogue of the cut locus, a notion classically studied in Differential Geometry, for finite graphs. The cut locus C(x) of a vertex x shall be the graph induced by the set of all vertices y with the property that no shortest path between x and z, z≠y, contains y. The cut locus ...

Universal conditions for finite renormalizable quantum field theories

International Nuclear Information System (INIS)

Kranner, G.

1990-10-01

Analyzing general renormalization constants in covariant gauge and minimal subtraction, we consider universal conditions for cancelling UV-divergences in renormalizable field theories with simple gauge groups, and give constructive methods for finding nonsupersymmetric finite models. The divergent parts of the renormalization constants for fields explicitly depend on the gauge parameter ξ. Finite theories simply need finite couplings. We show that respective FinitenessConditions imply a hierarchy, the center of which are the FCs for the gauge coupling g and the Yukawa couplings of the massless theory. To gain more information about F we analyze the Yukawa-FC in greater detail. Doing so algebraically, we find out and fix all inner symmetries. Additionally, Yuakawa-couplings must be invariant under gauge transformation. Then it becomes extremely difficult to obey a FC, yield rational numbers for F ∼ 1, and satisfy the factorization-condition, unless F = 1. The particular structure of the F = 1-system allows for a most general ansatz. We figure out the simplest case, getting precisely just couplings and particle content of a general N=1-supersymmetric theory. We list a class of roughly 4000 types of theories, containing all supersymmetric, completely finite, and many more finite theories as well. (Author, shortened by Quittner) 11 figs., 54 refs

Finite Range Decomposition of Gaussian Processes

CERN Document Server

Brydges, C D; Mitter, P K

2003-01-01

Let $D$ be the finite difference Laplacian associated to the lattice $bZ^{d}$. For dimension $dge 3$, $age 0$ and $L$ a sufficiently large positive dyadic integer, we prove that the integral kernel of the resolvent $G^{a}:=(a-D)^{-1}$ can be decomposed as an infinite sum of positive semi-definite functions $ V_{n} $ of finite range, $ V_{n} (x-y) = 0$ for $|x-y|ge O(L)^{n}$. Equivalently, the Gaussian process on the lattice with covariance $G^{a}$ admits a decomposition into independent Gaussian processes with finite range covariances. For $a=0$, $ V_{n} $ has a limiting scaling form $L^{-n(d-2)}Gamma_{ c,ast }{bigl (frac{x-y}{ L^{n}}bigr )}$ as $nrightarrow infty$. As a corollary, such decompositions also exist for fractional powers $(-D)^{-alpha/2}$, $0group on the lattice.

Profinite graphs and groups

CERN Document Server

Ribes, Luis

2017-01-01

This book offers a detailed introduction to graph theoretic methods in profinite groups and applications to abstract groups. It is the first to provide a comprehensive treatment of the subject. The author begins by carefully developing relevant notions in topology, profinite groups and homology, including free products of profinite groups, cohomological methods in profinite groups, and fixed points of automorphisms of free pro-p groups. The final part of the book is dedicated to applications of the profinite theory to abstract groups, with sections on finitely generated subgroups of free groups, separability conditions in free and amalgamated products, and algorithms in free groups and finite monoids. Profinite Graphs and Groups will appeal to students and researchers interested in profinite groups, geometric group theory, graphs and connections with the theory of formal languages. A complete reference on the subject, the book includes historical and bibliographical notes as well as a discussion of open quest...

The criticality problem in reflected slab type reactor in the two-group transport theory

International Nuclear Information System (INIS)

Garcia, R.D.M.

1978-01-01

The criticality problem in reflected slab type reactor is solved for the first time in the two group neutron transport theory, by singular eingenfunctions expansion, the singular integrals obtained through continuity conditions of angular distributions at the interface are regularized by a recently proposed method. The result is a coupled system of regular integral equations for the expansion coefficients, this system is solved by an ordinary interactive method. Numerical results that can be utilized as a comparative standard for aproximation methods, are presented [pt

Finite Unification: Theory, Models and Predictions

CERN Document Server

Heinemeyer, S; Zoupanos, G

2011-01-01

All-loop Finite Unified Theories (FUTs) are very interesting N=1 supersymmetric Grand Unified Theories (GUTs) realising an old field theory dream, and moreover have a remarkable predictive power due to the required reduction of couplings. The reduction of the dimensionless couplings in N=1 GUTs is achieved by searching for renormalization group invariant (RGI) relations among them holding beyond the unification scale. Finiteness results from the fact that there exist RGI relations among dimensional couplings that guarantee the vanishing of all beta-functions in certain N=1 GUTs even to all orders. Furthermore developments in the soft supersymmetry breaking sector of N=1 GUTs and FUTs lead to exact RGI relations, i.e. reduction of couplings, in this dimensionful sector of the theory, too. Based on the above theoretical framework phenomenologically consistent FUTs have been constructed. Here we review FUT models based on the SU(5) and SU(3)^3 gauge groups and their predictions. Of particular interest is the Hig...

Theory of the Andreev reflection and the density of states in proximity contact normal-superconducting infinite double-layer

International Nuclear Information System (INIS)

Nagato, Yasushi; Nagai, Katsuhiko

1993-01-01

Proximity contact N-S double-layer with infinite layer widths is studied in the clean limit. The finite reflection at the interface is taken into account. Starting from a recent theory of finite width double-layer by Ashida et al., the authors obtain explicit expressions for the quasi-classical Green's function which already satisfy the boundary condition and include no exploding terms at infinities. The self-consistent pair potentials are obtained numerically with sufficient accuracy. The Andreev reflection at the N-S interface is discussed on the basis of the self-consistent pair potential. It is shown that there exists a resonance state in a potential valley formed between the depressed pair potential and the partially reflecting interface, which leads to a peak of the Andreev reflection coefficient with the height unity slightly below the bulk superconductor energy gap. They also find general relationship between the Andreev reflection coefficient and the local density of states of the superconductor just at the interface

Hecke symmetries and characteristic relations on reflection equation algebras

International Nuclear Information System (INIS)

Gurevich, D.I.; Pyatov, P.N.

1996-01-01

We discuss how properties of Hecke symmetry (i.e., Hecke type R-matrix) influence the algebraic structure of the corresponding Reflection Equation (RE) algebra. Analogues of the Newton relations and Cayley-Hamilton theorem for the matrix of generators of the RE algebra related to a finite rank even Hecke symmetry are derived. 10 refs

A novel QC-LDPC code based on the finite field multiplicative group for optical communications

Science.gov (United States)

Yuan, Jian-guo; Xu, Liang; Tong, Qing-zhen

2013-09-01

A novel construction method of quasi-cyclic low-density parity-check (QC-LDPC) code is proposed based on the finite field multiplicative group, which has easier construction, more flexible code-length code-rate adjustment and lower encoding/decoding complexity. Moreover, a regular QC-LDPC(5334,4962) code is constructed. The simulation results show that the constructed QC-LDPC(5334,4962) code can gain better error correction performance under the condition of the additive white Gaussian noise (AWGN) channel with iterative decoding sum-product algorithm (SPA). At the bit error rate (BER) of 10-6, the net coding gain (NCG) of the constructed QC-LDPC(5334,4962) code is 1.8 dB, 0.9 dB and 0.2 dB more than that of the classic RS(255,239) code in ITU-T G.975, the LDPC(32640,30592) code in ITU-T G.975.1 and the SCG-LDPC(3969,3720) code constructed by the random method, respectively. So it is more suitable for optical communication systems.

A three-dimensional finite element model for biomechanical analysis of the hip.

Science.gov (United States)

Chen, Guang-Xing; Yang, Liu; Li, Kai; He, Rui; Yang, Bin; Zhan, Yan; Wang, Zhi-Jun; Yu, Bing-Nin; Jian, Zhe

2013-11-01

The objective of this study was to construct a three-dimensional (3D) finite element model of the hip. The images of the hip were obtained from Chinese visible human dataset. The hip model includes acetabular bone, cartilage, labrum, and bone. The cartilage of femoral head was constructed using the AutoCAD and Solidworks software. The hip model was imported into ABAQUS analysis system. The contact surface of the hip joint was meshed. To verify the model, the single leg peak force was loaded, and contact area of the cartilage and labrum of the hip and pressure distribution in these structures were observed. The constructed 3D hip model reflected the real hip anatomy. Further, this model reflected biomechanical behavior similar to previous studies. In conclusion, this 3D finite element hip model avoids the disadvantages of other construction methods, such as imprecision of cartilage construction and the absence of labrum. Further, it provides basic data critical for accurately modeling normal and abnormal loads, and the effects of abnormal loads on the hip.

Investigation of the reflection of fast neutrons

International Nuclear Information System (INIS)

Devillers, Christian; Hasselin, Gilbert

1964-10-01

The authors report the study of the reflection of fast neutrons on a plane plate having a finite and varying thickness and an infinite width. Calculations are performed by using a Monte-Carlo method which allows the number, the energy, the direction, the emergence point of neutrons reflected on a plate, to be computed with respect to the energy and direction of incident neutrons. The author present how paths, elastic and inelastic shocks, direction after shock are calculated. Different information are calculated: the numbers of elastic shocks, inelastic shocks and transmitted neutrons, the number, energy and dose albedo, the spectrum and angular distribution, the distribution of neutron in terms of energy and direction

A remark on the unitary group of a tensor product of n finite ...

Indian Academy of Sciences (India)

By using the method of quantum circuits in the theory of quantum computing as outlined in Nielsen and Chuang [2] and using a key lemma of Jaikumar [1] we show that every unitary operator on the tensor product H = H 1 ⊗ H 2 ⊗ … ⊗ H n can be expressed as a composition of a finite number of unitary operators living on ...

Neutron transmission and reflection at a copper single crystal

Energy Technology Data Exchange (ETDEWEB)

Adib, M.; Maayouf, R.M.A.; Abdel-Kawy, A.; Fayek, M.; Habib, N. (Atomic Energy Establishment, Cairo (Egypt). Reactor and Neutron Physics Dept.); Wahba, M. (Ain Shams Univ., Cairo (Egypt). Dept. of Engineering Physics and Mathematics)

1991-06-01

Neutron transmission and reflection at a copper single crystal cut along the (111) plane were studied with the fixed-scattering-angle spectrometer installed at the ET-RR-1 reactor. The transmission was measured for neutron wavelengths between 0.15 and 0.46 nm and various orientations of the (111) plane with respect to the incident beam. When used as a neutron band pass filter, the crystal is optimally oriented when the neutron beam is incident parallel to the (111) direction. The reflectivity was measured for the (111) plane at 45deg with respect to the incident beam. The results were found to be in reasonable agreement with a value predicted for the reflected intensity at an imperfect crystal with finite absorption. (orig.).

Neutron transmission and reflection at a copper single crystal

International Nuclear Information System (INIS)

Adib, M.; Maayouf, R.M.A.; Abdel-Kawy, A.; Fayek, M.; Habib, N.; Wahba, M.

1991-01-01

Neutron transmission and reflection at a copper single crystal cut along the (111) plane were studied with the fixed-scattering-angle spectrometer installed at the ET-RR-1 reactor. The transmission was measured for neutron wavelengths between 0.15 and 0.46 nm and various orientations of the (111) plane with respect to the incident beam. When used as a neutron band pass filter, the crystal is optimally oriented when the neutron beam is incident parallel to the [111] direction. The reflectivity was measured for the (111) plane at 45deg with respect to the incident beam. The results were found to be in reasonable agreement with a value predicted for the reflected intensity at an imperfect crystal with finite absorption. (orig.) [de

a constructive approach to the finite wavelet frames over prime fields

Indian Academy of Sciences (India)

6

The motivation of this paper is to establish an alternative constructive formulation for the wavelet coefficients of finite ... is a |G|-dimensional vector space with complex vector entries indexed by elements in the finite group G. The inner product of x,y ∈ CG is defined by .... Construction of Wavelet Frames over Prime Fields.

A mean field theory of study of lattice gauge theory with finite temperature and with finite fermion density

International Nuclear Information System (INIS)

Naik, S.

1990-01-01

We have developed a mean field theory technique to study the confinement-deconfinement phase transition and chiral symmetry restoring phase transition with dynamical fermions and with finite chemical potential and finite temperature. The approximation scheme concerns the saddle point scenario and large space dimension. The static quark-antiquark potentials are identified from the Wilson loop correlation functions in both the fundamental and the adjoint representation of the gauge group with different temperatures. The difference between the responses of the chemical potential to the fermion number with singlet and non-singlet isospin configuration is found. We compare our results with recent Monte Carlo data. (orig.)

Finite element and finite difference methods in electromagnetic scattering

CERN Document Server

Morgan, MA

2013-01-01

This second volume in the Progress in Electromagnetic Research series examines recent advances in computational electromagnetics, with emphasis on scattering, as brought about by new formulations and algorithms which use finite element or finite difference techniques. Containing contributions by some of the world's leading experts, the papers thoroughly review and analyze this rapidly evolving area of computational electromagnetics. Covering topics ranging from the new finite-element based formulation for representing time-harmonic vector fields in 3-D inhomogeneous media using two coupled sca

The simulation of electrostatic coupling intra-body communication based on the finite-element method

Institute of Scientific and Technical Information of China (English)

Song Yong; Zhang Kai; Yang Guang; Zhu Kang; Hao Qun

2011-01-01

In this paper, investigation has been done in the computer simulation of the electrostatic coupling IBC by using the developed finite-element models, in which a. the incidence and reflection of electronic signal in the upper arm model were analyzed by using the theory of electromagnetic wave; b. the finite-element models of electrostatic coupling IBC were developed by using the electromagnetic analysis package of ANSYS software; c. the signal attenuation of electrostatic coupling IBC were simulated under the conditions of different signal frequencies, electrodes directions, electrodes sizes and transmission distances. Finally, some important conclusions are deduced on the basis of simulation results.

A "safe space" for learning and reflection: one school's design for continuity with a peer group across clinical clerkships.

Science.gov (United States)

Chou, Calvin L; Johnston, C Bree; Singh, Bobby; Garber, Jonathan D; Kaplan, Elizabeth; Lee, Kewchang; Teherani, Arianne

2011-12-01

The value of continuity in medical education, particularly during clerkships, is increasingly recognized. Previous clerkship-based models have described changes that emphasize continuity in patient care, learner supervision, and curriculum. The creation of continuous student peer groups can foster interactions that enhance mutual support through uncomfortable professional transitions during the clerkship years. Here, the authors describe a third-year clerkship model based at the San Francisco Veterans Affairs (VA) Medical Center called VA Longitudinal Rotations (VALOR), designed explicitly to establish a supportive learning environment for small peer groups.Seven groups of medical students (42 total) completed VALOR across three academic years between 2007 and 2009. On clerkships during VALOR, one hour per week was designated for faculty-facilitated sessions amongst peer groups. Students' perceptions of peer group support and overall program satisfaction were determined with immediate post surveys and focus groups at the end of VALOR, and with follow-up surveys 5 to 27 months after completing VALOR. Students strongly valued several elements of VALOR peer groups, including support through clerkship challenges, meeting for facilitated reflection, and appreciating patient experiences across the continuum of care. Students' appreciation for their peer group experiences persisted well after the conclusion of VALOR. VALOR students performed the same as or better than traditional clerkship students on knowledge and skill-based outcomes. The authors demonstrate that their third-year clerkship program using peer groups has built supportive learning networks and facilitated reflection, allowing students to develop critical professional skills. Student communication around patient care was also feasible and highly valued.

Finite translation surfaces with maximal number of translations

OpenAIRE

Schlage-Puchta, Jan-Christoph; Weitze-Schmithuesen, Gabriela

2013-01-01

The natural automorphism group of a translation surface is its group of translations. For finite translation surfaces of genus g > 1 the order of this group is naturally bounded in terms of g due to a Riemann-Hurwitz formula argument. In analogy with classical Hurwitz surfaces, we call surfaces which achieve the maximal bound Hurwitz translation surfaces. We study for which g there exist Hurwitz translation surfaces of genus g.

Graded associative conformal algebras of finite type

OpenAIRE

Kolesnikov, Pavel

2011-01-01

In this paper, we consider graded associative conformal algebras. The class of these objects includes pseudo-algebras over non-cocommutative Hopf algebras of regular functions on some linear algebraic groups. In particular, an associative conformal algebra which is graded by a finite group $\\Gamma $ is a pseudo-algebra over the coordinate Hopf algebra of a linear algebraic group $G$ such that the identity component $G^0$ is the affine line and $G/G^0\\simeq \\Gamma $. A classification of simple...

A novel construction method of QC-LDPC codes based on the subgroup of the finite field multiplicative group for optical transmission systems

Science.gov (United States)

Yuan, Jian-guo; Zhou, Guang-xiang; Gao, Wen-chun; Wang, Yong; Lin, Jin-zhao; Pang, Yu

2016-01-01

According to the requirements of the increasing development for optical transmission systems, a novel construction method of quasi-cyclic low-density parity-check (QC-LDPC) codes based on the subgroup of the finite field multiplicative group is proposed. Furthermore, this construction method can effectively avoid the girth-4 phenomena and has the advantages such as simpler construction, easier implementation, lower encoding/decoding complexity, better girth properties and more flexible adjustment for the code length and code rate. The simulation results show that the error correction performance of the QC-LDPC(3 780,3 540) code with the code rate of 93.7% constructed by this proposed method is excellent, its net coding gain is respectively 0.3 dB, 0.55 dB, 1.4 dB and 1.98 dB higher than those of the QC-LDPC(5 334,4 962) code constructed by the method based on the inverse element characteristics in the finite field multiplicative group, the SCG-LDPC(3 969,3 720) code constructed by the systematically constructed Gallager (SCG) random construction method, the LDPC(32 640,30 592) code in ITU-T G.975.1 and the classic RS(255,239) code which is widely used in optical transmission systems in ITU-T G.975 at the bit error rate ( BER) of 10-7. Therefore, the constructed QC-LDPC(3 780,3 540) code is more suitable for optical transmission systems.

Composite Finite Sums

KAUST Repository

Alabdulmohsin, Ibrahim M.

2018-03-07

In this chapter, we extend the previous results of Chap. 2 to the more general case of composite finite sums. We describe what composite finite sums are and how their analysis can be reduced to the analysis of simple finite sums using the chain rule. We apply these techniques, next, on numerical integration and on some identities of Ramanujan.

Composite Finite Sums

KAUST Repository

Alabdulmohsin, Ibrahim M.

2018-01-01

In this chapter, we extend the previous results of Chap. 2 to the more general case of composite finite sums. We describe what composite finite sums are and how their analysis can be reduced to the analysis of simple finite sums using the chain rule. We apply these techniques, next, on numerical integration and on some identities of Ramanujan.

Using the IGCRA (individual, group, classroom reflective action technique to enhance teaching and learning in large accountancy classes

Directory of Open Access Journals (Sweden)

Cristina Poyatos

2011-02-01

Full Text Available First year accounting has generally been perceived as one of the more challenging first year business courses for university students. Various Classroom Assessment Techniques (CATs have been proposed to attempt to enrich and enhance student learning, with these studies generally positioning students as learners alone. This paper uses an educational case study approach and examines the implementation of the IGCRA (individual, group, classroom reflective action technique, a Classroom Assessment Technique, on first year accounting students’ learning performance. Building on theoretical frameworks in the areas of cognitive learning, social development, and dialogical learning, the technique uses reports to promote reflection on both learning and teaching. IGCRA was found to promote feedback on the effectiveness of student, as well as teacher satisfaction. Moreover, the results indicated formative feedback can assist to improve the learning and learning environment for a large group of first year accounting students. Clear guidelines for its implementation are provided in the paper.

[Group process: reflections of a nursing team].

Science.gov (United States)

Cardoso, Adriana Serdotte Freitas; Dall'Agnol, Clarice Maria

2011-12-01

The objective of this qualitative, exploratory-descriptive study was to analyze the group process of a nursing team at Hospital de Clínicas de Porto Alegre (HCPA), under the light of Pichon-Rivière's Operative Group Theory. Data collection took place in 2008, using a semi-structured questionnaire and focal group. The group work concept is one of the four categories that resulted from the study, and is the object of approach in the present article. It was found that the knowledge about the group process must be shared, disseminated and discussed since the undergraduate studies and developed across the professional career. As the team learns and is able to identify the main indicators of the group process, it becomes possible to improve operatively, considering not only the outcomes but mainly the course covered until achieving the goal, aiming at group learning.

A note on TI-subgroups of finite groups

Indian Academy of Sciences (India)

A kernel and a complement of a quasi-Frobenius group G are the preimages of a kernel and a complement of the Frobenius group G/Z(G), respectively. Lemma 1.2 [1]. A group G is quasi-Frobenius if and only if G possesses a noncentral subgroup H such that H ∩ Hg ≤ Z(G) for all g ∈ G − H. In this case, H is a comple-.

Axial anomaly at finite temperature and finite density

International Nuclear Information System (INIS)

Qian Zhixin; Su Rukeng; Yu, P.K.N.

1994-01-01

The U(1) axial anomaly in a hot fermion medium is investigated by using the real time Green's function method. After calculating the lowest order triangle diagrams, we find that finite temperature as well as finite fermion density does not affect the axial anomaly. The higher order corrections for the axial anomaly are discussed. (orig.)

Quantifying Reflection

DEFF Research Database (Denmark)

Alcock, Gordon Lindsay

2013-01-01

´ These are all based on Blooms taxonomy and levels of competence and form a major part of individual student and group learning portfolios. Key Words :Project-Based learning, Reflective Portfolios, Self assessment, Defining learning gains, Developing learning strategies , Reflections on and for learning....... It contrasts the students’ self-assessment in a range of ‘product’ skills such as Revit, Structural Design, Mathematics of construction, Technical Installations; as well as ‘process’ competencies such as ‘Working in a team’, Sharing knowledge, Maintaining a portfolio and Reflecting ON learning and FOR learning......This paper documents 1st semester student reflections on “learning to learn” in a team-based PBL environment with quantitative and qualitative student reflective feedback on the learning gains of 60 Architectural Technology and Construction Management students at VIA University College, Denmark...

Locally Finite Root Supersystems

OpenAIRE

Yousofzadeh, Malihe

2013-01-01

We introduce the notion of locally finite root supersystems as a generalization of both locally finite root systems and generalized root systems. We classify irreducible locally finite root supersystems.

Burnside structures of finite subgroups

International Nuclear Information System (INIS)

Lysenok, I G

2007-01-01

We establish conditions guaranteeing that a group B possesses the following property: there is a number l such that if elements w, x -1 wx,...,x -l+1 wx l-1 of B generate a finite subgroup G then x lies in the normalizer of G. These conditions are of a quite special form. They hold for groups with relations of the form x n =1 which appear as approximating groups for the free Burnside groups B(m,n) of sufficiently large even exponent n. We extract an algebraic assertion which plays an important role in all known approaches to substantial results on the groups B(m,n) of large even exponent, in particular, to proving their infiniteness. The main theorem asserts that when n is divisible by 16, B has the above property with l=6

A complete classification of minimal non-PS-groups

Indian Academy of Sciences (India)

Abstract. Let G be a finite group. A subgroup H of G is called s-permutable in G if it permutes with every Sylow subgroup of G, and G is called a PS-group if all minimal subgroups and cyclic subgroups with order 4 of G are s-permutable in G. In this paper, we give a complete classification of finite groups which are not ...

Global finite-time attitude stabilization for rigid spacecraft in the exponential coordinates

Science.gov (United States)

Shi, Xiao-Ning; Zhou, Zhi-Gang; Zhou, Di

2018-06-01

This paper addresses the global finite-time attitude stabilisation problem on the special orthogonal group (SO(3)) for a rigid spacecraft via homogeneous feedback approach. Considering the topological and geometric properties of SO(3), the logarithm map is utilised to transform the stabilisation problem on SO(3) into the one on its associated Lie algebra (?). A model-independent discontinuous state feedback plus dynamics compensation scheme is constructed to achieve the global finite-time attitude stabilisation in a coordinate-invariant way. In addition, to address the absence of angular velocity measurements, a sliding mode observer is proposed to reconstruct the unknown angular velocity information within finite time. Then, an observer-based finite-time output feedback control strategy is obtained. Numerical simulations are finally performed to demonstrate the effectiveness of the proposed finite-time controllers.

Simple Finite Sums

KAUST Repository

Alabdulmohsin, Ibrahim M.

2018-01-01

We will begin our treatment of summability calculus by analyzing what will be referred to, throughout this book, as simple finite sums. Even though the results of this chapter are particular cases of the more general results presented in later chapters, they are important to start with for a few reasons. First, this chapter serves as an excellent introduction to what summability calculus can markedly accomplish. Second, simple finite sums are encountered more often and, hence, they deserve special treatment. Third, the results presented in this chapter for simple finite sums will, themselves, be used as building blocks for deriving the most general results in subsequent chapters. Among others, we establish that fractional finite sums are well-defined mathematical objects and show how various identities related to the Euler constant as well as the Riemann zeta function can actually be derived in an elementary manner using fractional finite sums.

Simple Finite Sums

KAUST Repository

Alabdulmohsin, Ibrahim M.

2018-03-07

We will begin our treatment of summability calculus by analyzing what will be referred to, throughout this book, as simple finite sums. Even though the results of this chapter are particular cases of the more general results presented in later chapters, they are important to start with for a few reasons. First, this chapter serves as an excellent introduction to what summability calculus can markedly accomplish. Second, simple finite sums are encountered more often and, hence, they deserve special treatment. Third, the results presented in this chapter for simple finite sums will, themselves, be used as building blocks for deriving the most general results in subsequent chapters. Among others, we establish that fractional finite sums are well-defined mathematical objects and show how various identities related to the Euler constant as well as the Riemann zeta function can actually be derived in an elementary manner using fractional finite sums.

Polarization sensitivity testing of off-plane reflection gratings

Science.gov (United States)

Marlowe, Hannah; McEntaffer, Randal L.; DeRoo, Casey T.; Miles, Drew M.; Tutt, James H.; Laubis, Christian; Soltwisch, Victor

2015-09-01

Off-Plane reflection gratings were previously predicted to have different efficiencies when the incident light is polarized in the transverse-magnetic (TM) versus transverse-electric (TE) orientations with respect to the grating grooves. However, more recent theoretical calculations which rigorously account for finitely conducting, rather than perfectly conducting, grating materials no longer predict significant polarization sensitivity. We present the first empirical results for radially ruled, laminar groove profile gratings in the off-plane mount which demonstrate no difference in TM versus TE efficiency across our entire 300-1500 eV bandpass. These measurements together with the recent theoretical results confirm that grazing incidence off-plane reflection gratings using real, not perfectly conducting, materials are not polarization sensitive.

Finite-size scaling in two-dimensional superfluids

International Nuclear Information System (INIS)

Schultka, N.; Manousakis, E.

1994-01-01

Using the x-y model and a nonlocal updating scheme called cluster Monte Carlo, we calculate the superfluid density of a two-dimensional superfluid on large-size square lattices LxL up to 400x400. This technique allows us to approach temperatures close to the critical point, and by studying a wide range of L values and applying finite-size scaling theory we are able to extract the critical properties of the system. We calculate the superfluid density and from that we extract the renormalization-group beta function. We derive finite-size scaling expressions using the Kosterlitz-Thouless-Nelson renormalization group equations and show that they are in very good agreement with our numerical results. This allows us to extrapolate our results to the infinite-size limit. We also find that the universal discontinuity of the superfluid density at the critical temperature is in very good agreement with the Kosterlitz-Thouless-Nelson calculation and experiments

Women's reflections and actions regarding working after breast cancer surgery - a focus group study.

Science.gov (United States)

Nilsson, M I; Olsson, M; Wennman-Larsen, A; Petersson, L-M; Alexanderson, K

2013-07-01

To better understand processes affecting return to work (RTW) after breast cancer, more knowledge from the perspective of sickness absentees is warranted. Still, research based on women's own reasoning and actions in RTW is very scarce. This study aims to elucidate how women with breast cancer reflect and act on work-related issues. Thematic analyses of data from four focus group interviews with 23 women who had had breast cancer surgery in the previous 3-13 months were carried out. The five following themes of reflections regarding RTW were identified: 'health and functioning', 'self-esteem/integrity', 'value of work', 'relationships at work', and 'social circumstances'. These reflections were associated with the three identified themes of actions taken by the women: 'to work or to be sickness absent', 'to adjust work according to own needs or not', and 'to disclose or to hide one's cancer'. There was a distinct difference between women who experienced work as a source of well-being and those who needed a respite from work. This study adds knowledge to the process of RTW after breast cancer and focuses on factors that lead the women to an active role in this process. We point to the interplay between women's own preferences, perceived competence, outer opportunities, and the actions each woman take with regard to RTW, which need to be recognized by all stakeholders involved. Furthermore, it continues to be essential to address the specific issue of disclosure in the workplace because this may be distressing for women. Copyright © 2012 John Wiley & Sons, Ltd.

Three-dimensional finite element nonlinear dynamic analysis of pile groups for lateral transient and seismic excitations

International Nuclear Information System (INIS)

Maheshwari, B.K.; Truman, K.Z.; El Naggar, M.H.; Gould, P.L.

2004-01-01

The effects of material nonlinearity of soil and separation at the soil-pile interface on the dynamic behaviour of a single pile and pile groups are investigated. An advanced plasticity-based soil model, hierarchical single surface (HiSS), is incorporated in the finite element formulation. To simulate radiation effects, proper boundary conditions are used. The model and algorithm are verified with analytical results that are available for elastic and elastoplastic soil models. Analyses are performed for seismic excitation and for the load applied on the pile cap. For seismic analysis, both harmonic and transient excitations are considered. For loading on the pile cap, dynamic stiffness of the soil-pile system is derived and the effect of nonlinearity is investigated. The effects of spacing between piles are investigated, and it was found that the effect of soil nonlinearity on the seismic response is very much dependent on the frequency of excitation. For the loading on a pile cap, the nonlinearity increases the response for most of the frequencies of excitation while decreasing the dynamic stiffness of the soil-pile system. (author)

Derived equivalences for group rings

CERN Document Server

König, Steffen

1998-01-01

A self-contained introduction is given to J. Rickard's Morita theory for derived module categories and its recent applications in representation theory of finite groups. In particular, Broué's conjecture is discussed, giving a structural explanation for relations between the p-modular character table of a finite group and that of its "p-local structure". The book is addressed to researchers or graduate students and can serve as material for a seminar. It surveys the current state of the field, and it also provides a "user's guide" to derived equivalences and tilting complexes. Results and proofs are presented in the generality needed for group theoretic applications.

Finite moments approach to the time-dependent neutron transport equation

International Nuclear Information System (INIS)

Kim, Sang Hyun

1994-02-01

Currently, nodal techniques are widely used in solving the multidimensional diffusion equation because of savings in computing time and storage. Thanks to the development of computer technology, one can now solve the transport equation instead of the diffusion equation to obtain more accurate solution. The finite moments method, one of the nodal methods, attempts to represent the fluxes in the cell and on cell surfaces more rigorously by retaining additional spatial moments. Generally, there are two finite moments schemes to solve the time-dependent transport equation. In one, the time variable is treated implicitly with finite moments method in space variable (implicit finite moments method), the other method uses finite moments method in both space and time (space-time finite moments method). In this study, these two schemes are applied to two types of time-dependent neutron transport problems. One is a fixed source problem, the other a heterogeneous fast reactor problem with delayed neutrons. From the results, it is observed that the two finite moments methods give almost the same solutions in both benchmark problems. However, the space-time finite moments method requires a little longer computing time than that of the implicit finite moments method. In order to reduce the longer computing time in the space-time finite moments method, a new iteration strategy is exploited, where a few time-stepwise calculation, in which original time steps are grouped into several coarse time divisions, is performed sequentially instead of performing iterations over the entire time steps. This strategy results in significant reduction of the computing time and we observe that 2-or 3-stepwise calculation is preferable. In addition, we propose a new finite moments method which is called mixed finite moments method in this thesis. Asymptotic analysis for the finite moments method shows that accuracy of the solution in a heterogeneous problem mainly depends on the accuracy of the

Representation theory of finite monoids

CERN Document Server

Steinberg, Benjamin

2016-01-01

This first text on the subject provides a comprehensive introduction to the representation theory of finite monoids. Carefully worked examples and exercises provide the bells and whistles for graduate accessibility, bringing a broad range of advanced readers to the forefront of research in the area. Highlights of the text include applications to probability theory, symbolic dynamics, and automata theory. Comfort with module theory, a familiarity with ordinary group representation theory, and the basics of Wedderburn theory, are prerequisites for advanced graduate level study. Researchers in algebra, algebraic combinatorics, automata theory, and probability theory, will find this text enriching with its thorough presentation of applications of the theory to these fields. Prior knowledge of semigroup theory is not expected for the diverse readership that may benefit from this exposition. The approach taken in this book is highly module-theoretic and follows the modern flavor of the theory of finite dimensional ...

Groups, combinatorics and geometry

CERN Document Server

Ivanov, A A; Saxl, J

2003-01-01

Over the past 20 years, the theory of groups in particular simplegroups, finite and algebraic has influenced a number of diverseareas of mathematics. Such areas include topics where groups have beentraditionally applied, such as algebraic combinatorics, finitegeometries, Galois theory and permutation groups, as well as severalmore recent developments.

THE PROBLEMS AND ECONOMIC REFLECTIONS OF ENTERPRISES IN ROMANIA

Directory of Open Access Journals (Sweden)

Ileana (BĂDULESCU ANASTASE

2015-11-01

Full Text Available This study shows the problems and reflections of Romania,in the period after the aderation to EU, this being a period when all the economic activities will be tested according to their level of efficiency and productivity of work. Maintining the traditional form of organization of work, of investments of structure of the finite products may transform the country into a colony, into an exporter of raw materials and workforce in the EU. We can notice the same thing, based on our research, in the case of the Moldavian Republic: the exports and investments influence very little the economic growth. This is due to the reduced performances of Moldavian exporters, and, even more, to the uncompetitive structure on groups of products. Half of the Moldavian exports is assured by the agro-alimentary market, without noticing some obvious trends of specialization in other new branches. The cause of this trend is the weak productive potential of national agriculture and industry (Anastase.I 2010.

Optimized Finite-Difference Coefficients for Hydroacoustic Modeling

Science.gov (United States)

Preston, L. A.

2014-12-01

Responsible utilization of marine renewable energy sources through the use of current energy converter (CEC) and wave energy converter (WEC) devices requires an understanding of the noise generation and propagation from these systems in the marine environment. Acoustic noise produced by rotating turbines, for example, could adversely affect marine animals and human-related marine activities if not properly understood and mitigated. We are utilizing a 3-D finite-difference acoustic simulation code developed at Sandia that can accurately propagate noise in the complex bathymetry in the near-shore to open ocean environment. As part of our efforts to improve computation efficiency in the large, high-resolution domains required in this project, we investigate the effects of using optimized finite-difference coefficients on the accuracy of the simulations. We compare accuracy and runtime of various finite-difference coefficients optimized via criteria such as maximum numerical phase speed error, maximum numerical group speed error, and L-1 and L-2 norms of weighted numerical group and phase speed errors over a given spectral bandwidth. We find that those coefficients optimized for L-1 and L-2 norms are superior in accuracy to those based on maximal error and can produce runtimes of 10% of the baseline case, which uses Taylor Series finite-difference coefficients at the Courant time step limit. We will present comparisons of the results for the various cases evaluated as well as recommendations for utilization of the cases studied. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

On some homological functors of a Bieberbach group with symmetric point group

Science.gov (United States)

Ting, Tan Yee; Idrus, Nor'ashiqin Mohd; Masri, Rohaidah; Ladi, Nor Fadzilah Abdul

2017-05-01

Bieberbach groups with symmetric point group are polycyclic. The properties of the groups can be explored by computing their homological functors. In this paper, some homological functors of a Bieberbach group with symmetric point group, such as the Schur multiplier and the G-trivial subgroup of the nonabelian tensor square, are generalized up to finite dimension and are represented in the form of direct product of cyclic groups.

Groebner Finite Path Algebras

OpenAIRE

Leamer, Micah J.

2004-01-01

Let K be a field and Q a finite directed multi-graph. In this paper I classify all path algebras KQ and admissible orders with the property that all of their finitely generated ideals have finite Groebner bases. MS

Height in splittings of hyperbolic groups

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

of G. We choose a finite symmetric generating set for H and extend it to a finite ...... [10] Bonahon F, Geodesic currents on negatively curved groups, in: Arboreal ... [14] Canary R D, Epstein D B A and Green P, Notes on notes of Thurston, in: ...

Automorphisms of free groups with boundaries

DEFF Research Database (Denmark)

A. Jensen, Craig; Wahl, Nathalie

2004-01-01

The automorphisms of free groups with boundaries form a family of groups A_{n,k} closely related to mapping class groups, with the standard automorphisms of free groups as A_{n,0} and (essentially) the symmetric automorphisms of free groups as A_{0,k}. We construct a contractible space L_{n,k} on......The automorphisms of free groups with boundaries form a family of groups A_{n,k} closely related to mapping class groups, with the standard automorphisms of free groups as A_{n,0} and (essentially) the symmetric automorphisms of free groups as A_{0,k}. We construct a contractible space L......_{n,k} on which A_{n,k} acts with finite stabilizers and finite quotient space and deduce a range for the virtual cohomological dimension of A_{n,k}. We also give a presentation of the groups and calculate their first homology group....

Finite-Element Modeling of Timber Joints with Punched Metal Plate Fasteners

DEFF Research Database (Denmark)

Ellegaard, Peter

2006-01-01

The focus of this paper is to describe the idea and the theory behind a finite-element model developed for analysis of timber trusses with punched metal plate fasteners (nail plates). The finite-element model includes the semirigid and nonlinear behavior of the joints (nonlinear nail and plate...... elements) and contact between timber beams, if any (bilinear contact elements). The timber beams have linear-elastic properties. The section forces needed for design of the joints are given directly by the finite-element model, since special elements are used to model the nail groups and the nail plate...... the behavior of the joints very well at lower load levels. At higher load levels the stiffness is overestimated due to development of cracks in the timber and the linear-elastic timber properties in the finite-element model....

Finite volume form factors in the presence of integrable defects

International Nuclear Information System (INIS)

Bajnok, Z.; Buccheri, F.; Hollo, L.; Konczer, J.; Takacs, G.

2014-01-01

We developed the theory of finite volume form factors in the presence of integrable defects. These finite volume form factors are expressed in terms of the infinite volume form factors and the finite volume density of states and incorporate all polynomial corrections in the inverse of the volume. We tested our results, in the defect Lee–Yang model, against numerical data obtained by truncated conformal space approach (TCSA), which we improved by renormalization group methods adopted to the defect case. To perform these checks we determined the infinite volume defect form factors in the Lee–Yang model exactly, including their vacuum expectation values. We used these data to calculate the two point functions, which we compared, at short distance, to defect CFT. We also derived explicit expressions for the exact finite volume one point functions, which we checked numerically. In all of these comparisons excellent agreement was found

Gluon and ghost correlation functions of 2-color QCD at finite density

Science.gov (United States)

Hajizadeh, Ouraman; Boz, Tamer; Maas, Axel; Skullerud, Jon-Ivar

2018-03-01

2-color QCD, i. e. QCD with the gauge group SU(2), is the simplest non-Abelian gauge theory without sign problem at finite quark density. Therefore its study on the lattice is a benchmark for other non-perturbative approaches at finite density. To provide such benchmarks we determine the minimal-Landau-gauge 2-point and 3-gluon correlation functions of the gauge sector and the running gauge coupling at finite density. We observe no significant effects, except for some low-momentum screening of the gluons at and above the supposed high-density phase transition.

The Determining Finite Automata Process

Directory of Open Access Journals (Sweden)

M. S. Vinogradova

2017-01-01

Full Text Available The theory of formal languages widely uses finite state automata both in implementation of automata-based approach to programming, and in synthesis of logical control algorithms.To ensure unambiguous operation of the algorithms, the synthesized finite state automata must be deterministic. Within the approach to the synthesis of the mobile robot controls, for example, based on the theory of formal languages, there are problems concerning the construction of various finite automata, but such finite automata, as a rule, will not be deterministic. The algorithm of determinization can be applied to the finite automata, as specified, in various ways. The basic ideas of the algorithm of determinization can be most simply explained using the representations of a finite automaton in the form of a weighted directed graph.The paper deals with finite automata represented as weighted directed graphs, and discusses in detail the procedure for determining the finite automata represented in this way. Gives a detailed description of the algorithm for determining finite automata. A large number of examples illustrate a capability of the determinization algorithm.

Basic Finite Element Method

International Nuclear Information System (INIS)

Lee, Byeong Hae

1992-02-01

This book gives descriptions of basic finite element method, which includes basic finite element method and data, black box, writing of data, definition of VECTOR, definition of matrix, matrix and multiplication of matrix, addition of matrix, and unit matrix, conception of hardness matrix like spring power and displacement, governed equation of an elastic body, finite element method, Fortran method and programming such as composition of computer, order of programming and data card and Fortran card, finite element program and application of nonelastic problem.

Finite element calculation of the interaction energy of shape memory alloy

International Nuclear Information System (INIS)

Yang, Seung Yong

2004-01-01

Strain energy due to the mechanical interaction between self-accommodation groups of martensitic phase transformation is called interaction energy. Evaluation of the interaction energy should be accurate since the energy appears in constitutive models for predicting the mechanical behavior of shape memory alloy. In this paper, the interaction energy is evaluated in terms of theoretical formulation and explicit finite element calculation. A simple example with two habit plane variants was considered. It was shown that the theoretical formulation assuming elastic interaction between the self-accommodation group and matrix gives larger interaction energy than explicit finite element calculation in which transformation softening is accounted for

Architects of symmetry in finite nonabelian groups

Czech Academy of Sciences Publication Activity Database

Křížek, Michal; Somer, L.

2010-01-01

Roč. 21, č. 4 (2010), s. 307-319 ISSN 0865-4824 R&D Projects: GA AV ČR(CZ) IAA100190803 Institutional research plan: CEZ:AV0Z10190503 Keywords : Abel Prize * sporadic groups * monster Subject RIV: BA - General Mathematics

Energy stable and high-order-accurate finite difference methods on staggered grids

Science.gov (United States)

O'Reilly, Ossian; Lundquist, Tomas; Dunham, Eric M.; Nordström, Jan

2017-10-01

For wave propagation over distances of many wavelengths, high-order finite difference methods on staggered grids are widely used due to their excellent dispersion properties. However, the enforcement of boundary conditions in a stable manner and treatment of interface problems with discontinuous coefficients usually pose many challenges. In this work, we construct a provably stable and high-order-accurate finite difference method on staggered grids that can be applied to a broad class of boundary and interface problems. The staggered grid difference operators are in summation-by-parts form and when combined with a weak enforcement of the boundary conditions, lead to an energy stable method on multiblock grids. The general applicability of the method is demonstrated by simulating an explosive acoustic source, generating waves reflecting against a free surface and material discontinuity.

Finite element analysis of the neutron transport equation in spherical geometry

International Nuclear Information System (INIS)

Kim, Yong Ill; Kim, Jong Kyung; Suk, Soo Dong

1992-01-01

The Galerkin formulation of the finite element method is applied to the integral law of the first-order form of the one-group neutron transport equation in one-dimensional spherical geometry. Piecewise linear or quadratic Lagrange polynomials are utilized in the integral law for the angular flux to establish a set of linear algebraic equations. Numerical analyses are performed for the scalar flux distribution in a heterogeneous sphere as well as for the criticality problem in a uniform sphere. For the criticality problems in the uniform sphere, the results of the finite element method, with the use of continuous finite elements in space and angle, are compared with the exact solutions. In the heterogeneous problem, the scalar flux distribution obtained by using discontinuous angular and spatical finite elements is in good agreement with that from the ANISN code calculation. (Author)

A hybrid scheme for absorbing edge reflections in numerical modeling of wave propagation

KAUST Repository

Liu, Yang; Sen, Mrinal K.

2010-01-01

We propose an efficient scheme to absorb reflections from the model boundaries in numerical solutions of wave equations. This scheme divides the computational domain into boundary, transition, and inner areas. The wavefields within the inner and boundary areas are computed by the wave equation and the one-way wave equation, respectively. The wavefields within the transition area are determined by a weighted combination of the wavefields computed by the wave equation and the one-way wave equation to obtain a smooth variation from the inner area to the boundary via the transition zone. The results from our finite-difference numerical modeling tests of the 2D acoustic wave equation show that the absorption enforced by this scheme gradually increases with increasing width of the transition area. We obtain equally good performance using pseudospectral and finite-element modeling with the same scheme. Our numerical experiments demonstrate that use of 10 grid points for absorbing edge reflections attains nearly perfect absorption. © 2010 Society of Exploration Geophysicists.

A hybrid scheme for absorbing edge reflections in numerical modeling of wave propagation

KAUST Repository

Liu, Yang

2010-03-01

We propose an efficient scheme to absorb reflections from the model boundaries in numerical solutions of wave equations. This scheme divides the computational domain into boundary, transition, and inner areas. The wavefields within the inner and boundary areas are computed by the wave equation and the one-way wave equation, respectively. The wavefields within the transition area are determined by a weighted combination of the wavefields computed by the wave equation and the one-way wave equation to obtain a smooth variation from the inner area to the boundary via the transition zone. The results from our finite-difference numerical modeling tests of the 2D acoustic wave equation show that the absorption enforced by this scheme gradually increases with increasing width of the transition area. We obtain equally good performance using pseudospectral and finite-element modeling with the same scheme. Our numerical experiments demonstrate that use of 10 grid points for absorbing edge reflections attains nearly perfect absorption. © 2010 Society of Exploration Geophysicists.

A finite landscape?

International Nuclear Information System (INIS)

Acharya, B.S.; Douglas, M.R.

2006-06-01

We present evidence that the number of string/M theory vacua consistent with experiments is finite. We do this both by explicit analysis of infinite sequences of vacua and by applying various mathematical finiteness theorems. (author)

Fractional finite Fourier transform.

Science.gov (United States)

Khare, Kedar; George, Nicholas

2004-07-01

We show that a fractional version of the finite Fourier transform may be defined by using prolate spheroidal wave functions of order zero. The transform is linear and additive in its index and asymptotically goes over to Namias's definition of the fractional Fourier transform. As a special case of this definition, it is shown that the finite Fourier transform may be inverted by using information over a finite range of frequencies in Fourier space, the inversion being sensitive to noise. Numerical illustrations for both forward (fractional) and inverse finite transforms are provided.

Optimal reflection-free complex absorbing potentials for quantum propagation of wave packets

International Nuclear Information System (INIS)

Shemer, Oded; Brisker, Daria; Moiseyev, Nimrod

2005-01-01

The conditions for optimal reflection-free complex-absorbing potentials (CAPs) are discussed. It is shown that the CAPs as derived from the smooth-exterior-scaling transformation of the Hamiltonian [J. Phys. B 31, 1431 (1998)] serve as optimal reflection-free CAPs (RF CAPs) in wave-packet propagation calculations of open systems. The initial wave packet, Φ(t=0), can be located in the interaction region (as in half collision experiments) where the CAPs have vanished or in the asymptote where V CAP ≠0. As we show, the optimal CAPs can be introduced also in the region where the physical potential has not vanished. The unavoided reflections due to the use of a finite number of grid points (or basis functions) are discussed. A simple way to reduce the 'edge-grid' reflection effect is described

The finite-difference and finite-element modeling of seismic wave propagation and earthquake motion

International Nuclear Information System (INIS)

Moszo, P.; Kristek, J.; Galis, M.; Pazak, P.; Balazovijech, M.

2006-01-01

Numerical modeling of seismic wave propagation and earthquake motion is an irreplaceable tool in investigation of the Earth's structure, processes in the Earth, and particularly earthquake phenomena. Among various numerical methods, the finite-difference method is the dominant method in the modeling of earthquake motion. Moreover, it is becoming more important in the seismic exploration and structural modeling. At the same time we are convinced that the best time of the finite-difference method in seismology is in the future. This monograph provides tutorial and detailed introduction to the application of the finite-difference, finite-element, and hybrid finite-difference-finite-element methods to the modeling of seismic wave propagation and earthquake motion. The text does not cover all topics and aspects of the methods. We focus on those to which we have contributed. (Author)

Nonlinear reflection of shock shear waves in soft elastic media.

Science.gov (United States)

Pinton, Gianmarco; Coulouvrat, François; Gennisson, Jean-Luc; Tanter, Mickaël

2010-02-01

For fluids, the theoretical investigation of shock wave reflection has a good agreement with experiments when the incident shock Mach number is large. But when it is small, theory predicts that Mach reflections are physically unrealistic, which contradicts experimental evidence. This von Neumann paradox is investigated for shear shock waves in soft elastic solids with theory and simulations. The nonlinear elastic wave equation is approximated by a paraxial wave equation with a cubic nonlinear term. This equation is solved numerically with finite differences and the Godunov scheme. Three reflection regimes are observed. Theory is developed for shock propagation by applying the Rankine-Hugoniot relations and entropic constraints. A characteristic parameter relating diffraction and non-linearity is introduced and its theoretical values are shown to match numerical observations. The numerical solution is then applied to von Neumann reflection, where curved reflected and Mach shocks are observed. Finally, the case of weak von Neumann reflection, where there is no reflected shock, is examined. The smooth but non-monotonic transition between these three reflection regimes, from linear Snell-Descartes to perfect grazing case, provides a solution to the acoustical von Neumann paradox for the shear wave equation. This transition is similar to the quadratic non-linearity in fluids.

Transmission and Andreev reflection in one-dimensional chain with randomly doped superconducting grains

International Nuclear Information System (INIS)

Hu Dongsheng; Xiong Shijie

2002-01-01

We investigate the transport properties and Andreev reflection in one-dimensional (1D) systems with randomly doped superconducting grains. The superconducting grains are described by the Bogoliubov-de Gene Hamiltonian and the conductance is calculated by using the transfer matrix method and Landauer-Buettiker formula. It is found that although the quasiparticle states are localized due to the randomness and the low dimensionality, the conductance is still kept finite in the thermodynamical limit due to the Andreev reflection. We also investigate the effect of correlation of disorder in such systems and the results show the delocalization of quasiparticle states and suppression of Andreev reflection in a wide energy window

Time-dependent radiation transfer with rayleigh scattering in finite plane-parallel media using pomraning-eddington approximation

International Nuclear Information System (INIS)

El-Wakil, S.A.; Sallah, M.; Degheidy, A.R.

2005-01-01

The time-dependent radiation transfer equation in plane geometry with Rayleigh scattering is studied. The traveling wave transformation is used to obtain the corresponding stationary-like equation. Pomraning-Eddington approximation is then used to calculate the radiation intensity in finite plane-parallel media. Numerical results and shielding calculations are shown for reflectivity and transmissivity at different times. The medium is assumed to have specular-reflecting boundaries. For the sake of comparison, two different weight functions are introduced and to force the boundary conditions to be fulfilled

Groups acting on CAT(0) cube complexes

OpenAIRE

Niblo, Graham A.; Reeves, Lawrence

1997-01-01

We show that groups satisfying Kazhdan's property (T) have no unbounded actions on finite dimensional CAT(0) cube complexes, and deduce that there is a locally CAT(-1) Riemannian manifold which is not homotopy equivalent to any finite dimensional, locally CAT(0) cube complex.

Sensitivity of Ocean Reflectance Inversion Models for Identifying and Discriminating Between Phytoplankton Functional Groups

Science.gov (United States)

Werdell, P. Jeremy; Ooesler, Collin S.

2012-01-01

The daily, synoptic images provided by satellite ocean color instruments provide viable data streams for observing changes in the biogeochemistrY of marine ecosystems. Ocean reflectance inversion models (ORMs) provide a common mechanism for inverting the "color" of the water observed a satellite into marine inherent optical properties (lOPs) through a combination of empiricism and radiative transfer theory. lOPs, namely the spectral absorption and scattering characteristics of ocean water and its dissolved and particulate constituents, describe the contents of the upper ocean, information critical for furthering scientific understanding of biogeochemical oceanic processes. Many recent studies inferred marine particle sizes and discriminated between phytoplankton functional groups using remotely-sensed lOPs. While all demonstrated the viability of their approaches, few described the vertical distributions of the water column constituents under consideration and, thus, failed to report the biophysical conditions under which their model performed (e.g., the depth and thickness of the phytoplankton bloom(s)). We developed an ORM to remotely identifY Noctiluca miliaris and other phytoplankton functional types using satellite ocean color data records collected in the northern Arabian Sea. Here, we present results from analyses designed to evaluate the applicability and sensitivity of the ORM to varied biophysical conditions. Specifically, we: (1) synthesized a series of vertical profiles of spectral inherent optical properties that represent a wide variety of bio-optical conditions for the northern Arabian Sea under aN Miliaris bloom; (2) generated spectral remote-sensing reflectances from these profiles using Hydrolight; and, (3) applied the ORM to the synthesized reflectances to estimate the relative concentrations of diatoms and N Miliaris for each example. By comparing the estimates from the inversion model to those from synthesized vertical profiles, we were able to

Exact solution of a key equation in a finite stellar atmosphere by the method of Laplace transform and linear singular operators

International Nuclear Information System (INIS)

Das, R.N.

1980-01-01

The key equation which commonly appears for radiative transfer in a finite stellar atmosphere having ground reflection according to Lambert's law is considered in this paper. The exact solution of this equation is obtained for surface quantities in terms of the X-Y equations of Chandrasekhar by the method of Laplace transform and linear singular operators. This exact method is widely applicable for obtaining the solution for surface quantities in a finite atmosphere. (orig.)

High-Order Entropy Stable Finite Difference Schemes for Nonlinear Conservation Laws: Finite Domains

Science.gov (United States)

Fisher, Travis C.; Carpenter, Mark H.

2013-01-01

Developing stable and robust high-order finite difference schemes requires mathematical formalism and appropriate methods of analysis. In this work, nonlinear entropy stability is used to derive provably stable high-order finite difference methods with formal boundary closures for conservation laws. Particular emphasis is placed on the entropy stability of the compressible Navier-Stokes equations. A newly derived entropy stable weighted essentially non-oscillatory finite difference method is used to simulate problems with shocks and a conservative, entropy stable, narrow-stencil finite difference approach is used to approximate viscous terms.

A note on conjugacy classes of finite groups

Indian Academy of Sciences (India)

A group G is called a rational group if every element x of G is conjugate to xm, where m is a natural number coprime to |x|. By Re(G) we denote the set of all real elements of G and by (G) we denote the set of all the primes dividing the order of G. By F(G) we denote the fitting subgroup of G and Op(G) denotes the unique ...

Phytoplankton Group Identification Using Simulated and In situ Hyperspectral Remote Sensing Reflectance

Directory of Open Access Journals (Sweden)

Hongyan Xi

2017-08-01

Full Text Available In the present study we investigate the bio-geo-optical boundaries for the possibility to identify dominant phytoplankton groups from hyperspectral ocean color data. A large dataset of simulated remote sensing reflectance spectra, Rrs(λ, was used. The simulation was based on measured inherent optical properties of natural water and measurements of five phytoplankton light absorption spectra representing five major phytoplankton spectral groups. These simulated data, named as C2X data, contain more than 105 different water cases, including cases typical for clearest natural waters as well as for extreme absorbing and extreme scattering waters. For the simulation the used concentrations of chlorophyll a (representing phytoplankton abundance, Chl, are ranging from 0 to 200 mg m−3, concentrations of non-algal particles, NAP, from 0 to 1,500 g m−3, and absorption coefficients of chromophoric dissolved organic matter (CDOM at 440 nm from 0 to 20 m−1. A second, independent, smaller dataset of simulated Rrs(λ used light absorption spectra of 128 cultures from six phytoplankton taxonomic groups to represent natural variability. Spectra of this test dataset are compared with spectra from the C2X data in order to evaluate to which extent the five spectral groups can be correctly identified as dominant under different optical conditions. The results showed that the identification accuracy is highly subject to the water optical conditions, i.e., contribution of and covariance in Chl, NAP, and CDOM. The identification in the simulated data is generally effective, except for waters with very low contribution by phytoplankton and for waters dominated by NAP, whereas contribution by CDOM plays only a minor role. To verify the applicability of the presented approach for natural waters, a test using in situ Rrs(λ dataset collected during a cyanobacterial bloom in Lake Taihu (China is carried out and the approach predicts blue cyanobacteria to be dominant

Finite rotation shells basic equations and finite elements for Reissner kinematics

CERN Document Server

Wisniewski, K

2010-01-01

This book covers theoretical and computational aspects of non-linear shells. Several advanced topics of shell equations and finite elements - not included in standard textbooks on finite elements - are addressed, and the book includes an extensive bibliography.

Reflections of a Group of South African Teenage Mothers: Sexual Health Implications

Science.gov (United States)

Singh, Shakila; Hamid, Alvi

2016-01-01

Objectives: In the context of women's vulnerability to sexual violence, HIV infection and unintended pregnancy in South Africa, this paper explores the ways in which teenage mothers who are in school reflect on their experiences of pregnancy and motherhood. We attempt to understand how teenage mothers reflect on their experiences within the…

Global Explorers Journaling and Reflection Initiative

Directory of Open Access Journals (Sweden)

John Bennion

2016-12-01

Full Text Available Research suggests that journaling will increase reflection and improve program outcomes (Bain, et al, 1999; Duerden, et al, 2012 This study involved a partnership with a non-profit, Global Explorers (GEx, which provides international immersion experiences for youth. Their programs are designed to teach youth participants principles of leadership, environmental awareness, service, and science. This study, which tested whether teaching journaling techniques to youth program facilitators would have a positive impact on participant outcomes, addressed the following hypotheses: 1 Greater training in reflective thinking among participants would be associated with higher outcome scores, and 2 Participants in the intervention group (facilitators trained in journaling pedagogy would show greater increases in reflective thinking than comparison group members. Results based on participant self-assessment were significant in testing the first hypothesis; reflective thinking is positively associated with outcome measures, but the intervention group did not show increases in reflective thinking.

Quantum phase crossovers with finite atom number in the Dicke model

International Nuclear Information System (INIS)

Hirsch, J G; Castaños, O; Nahmad-Achar, E; López-Peña, R

2013-01-01

Two-level atoms interacting with a one-mode cavity field at zero temperature have order parameters which reflect the presence of a quantum phase transition at a critical value of the atom–cavity coupling strength. Two popular examples are the number of photons inside the cavity and the number of excited atoms. Coherent states provide a mean field description, which becomes exact in the thermodynamic limit. Employing symmetry-adapted (SA) SU(2) coherent states the quantum crossover, precursor of the critical behavior, can be described for a finite number of atoms. A variation after projection treatment, involving a numerical minimization of the SA energy surface, associates the quantum crossover with a discontinuity in the order parameters, which originates from competition between two local minima in the SA energy surface. Although this discontinuity is not present in finite systems, it provides a good description of 1/N effects in the observables. (paper)

Influence of particle and surface quality on the vitrinite reflectance of dispersed organic matter: Comparative exercise using data from the qualifying system for reflectance analysis working group of ICCP

Science.gov (United States)

Borrego, A.G.; Araujo, C.V.; Balke, A.; Cardott, B.; Cook, A.C.; David, P.; Flores, D.; Hamor-Vido, M.; Hiltmann, W.; Kalkreuth, W.; Koch, J.; Kommeren, C.J.; Kus, J.; Ligouis, B.; Marques, M.; Mendonca, Filho J.G.; Misz, M.; Oliveira, L.; Pickel, W.; Reimer, K.; Ranasinghe, P.; Suarez-Ruiz, I.; Vieth, A.

2006-01-01

The development of a qualifying system for reflectance analysis has been the scope of a working group within the International Committee for Coal and Organic Petrology (ICCP) since 1999, when J. Koch presented a system to qualify vitrinite particles according to their size, proximity to bright components and homogeneity of the surface. After some years of work aimed at improving the classification system using photomicrographs, it was decided to run a round robin exercise on microscopy samples. The classification system tested consists of three qualifiers ranging from excellent to low quality vitrinites with an additional option for unsuitable vitrinites. This paper reports on the results obtained by 22 analysts who were asked to measure random reflectance readings on vitrinite particles assigning to each reading a qualifier. Four samples containing different organic matter types and a variety of vitrinite occurrences have been analysed. Results indicated that the reflectance of particles classified as excellent, good or poor compared to the total average reflectance did not show trends to be systematically lower or higher for the four samples analysed. The differences in reflectance between the qualifiers for any given sample were lower than the scatter of vitrinite reflectance among participants. Overall, satisfactory results were obtained in determining the reflectance of vitrinite in the four samples analysed. This was so for samples having abundant and easy to identify vitrinites (higher plant-derived organic matter) as well as for samples with scarce and difficult to identify particles (samples with dominant marine-derived organic matter). The highest discrepancies were found for the organic-rich oil shales where the selection of the vitrinite population to measure proved to be particularly difficult. Special instructions should be provided for the analysis of this sort of samples. The certainty of identification of the vitrinite associated with the vitrinite

Finite Boltzmann schemes

NARCIS (Netherlands)

Sman, van der R.G.M.

2006-01-01

In the special case of relaxation parameter = 1 lattice Boltzmann schemes for (convection) diffusion and fluid flow are equivalent to finite difference/volume (FD) schemes, and are thus coined finite Boltzmann (FB) schemes. We show that the equivalence is inherent to the homology of the

Development of a partitioned finite volume-finite element fluid-structure interaction scheme for strongly-coupled problems

CSIR Research Space (South Africa)

Suliman, Ridhwaan

2012-07-01

Full Text Available -linear deformations are accounted for. As will be demonstrated, the finite volume approach exhibits similar disad- vantages to the linear Q4 finite element formulation when undergoing bending. An enhanced finite volume approach is discussed and compared with finite...

Finite element analysis-based study of fiber Bragg grating sensor for cracks detection in reinforced concrete

Science.gov (United States)

Wang, Lili; Xin, Xiangjun; Song, Jun; Wang, Honggang; Sai, Yaozhang

2018-02-01

Fiber Bragg sensor is applied for detecting and monitoring the cracks that occur in the reinforced concrete. We use the three-dimensional finite element model to provide the three-axial stresses along the fiber Bragg sensor and then converted the stresses as a wavelength deformation of fiber Bragg grating (FBG) reflected spectrum. For the crack detection, an FBG sensor with 10-mm length is embedded in the reinforced concrete, and its reflection spectrum is measured after loading is applied to the concrete slab. As a result, the main peak wavelength and the ratio of the peak reflectivity to the maximal side-mode reflectivity of the optic-fiber grating represent the fracture severity. The fact that the sharp decreasing of the ratio of the peak reflectivity to the maximal side-mode reflectivity represents the early crack is confirmed by the theoretical calculation. The method can be used to detect the cracks in the reinforced concrete and give safety evaluation of large-scale infrastructure.

Hypercontractivity in group Von Neumann algebras

CERN Document Server

Junge, Marius; Parcet, Javier

2017-01-01

In this paper, the authors provide a combinatorial/numerical method to establish new hypercontractivity estimates in group von Neumann algebras. They illustrate their method with free groups, triangular groups and finite cyclic groups, for which they obtain optimal time hypercontractive L_2 \\to L_q inequalities with respect to the Markov process given by the word length and with q an even integer. Interpolation and differentiation also yield general L_p \\to L_q hypercontrativity for 1 < p \\le q < \\infty via logarithmic Sobolev inequalities. The authors' method admits further applications to other discrete groups without small loops as far as the numerical part-which varies from one group to another-is implemented and tested on a computer. The authors also develop another combinatorial method which does not rely on computational estimates and provides (non-optimal) L_p \\to L_q hypercontractive inequalities for a larger class of groups/lengths, including any finitely generated group equipped with a condit...

On derived groups of division rings II

International Nuclear Information System (INIS)

Mahdavi Hezavehi, M.; Akbari Feyzaabaadi, S.; Mehraabaadi, M.; Hajie Abolhassan, H.

1995-05-01

Let D be a division ring with centre F and denote by D' the derived group (commutator subgroup) of D * = D - {0}. It is shown that if each element of D' is algebraic over F, then D is algebraic over F. It is also proved that each finite separable extension of F in D is of the form F(c) for some element c in the derived group D'. Using these results, it is shown that if each element of the derived group D' is of bounded degree over F, then D is finite dimensional over F. (author). 5 refs

Finite quantum field theories

International Nuclear Information System (INIS)

Lucha, W.; Neufeld, H.

1986-01-01

We investigate the relation between finiteness of a four-dimensional quantum field theory and global supersymmetry. To this end we consider the most general quantum field theory and analyse the finiteness conditions resulting from the requirement of the absence of divergent contributions to the renormalizations of the parameters of the theory. In addition to the gauge bosons, both fermions and scalar bosons turn out to be a necessary ingredient in a non-trivial finite gauge theory. In all cases discussed, the supersymmetric theory restricted by two well-known constraints on the dimensionless couplings proves to be the unique solution of the finiteness conditions. (Author)

Groups and Geometries : Siena Conference

CERN Document Server

Kantor, William; Lunardon, Guglielmo; Pasini, Antonio; Tamburini, Maria

1998-01-01

On September 1-7, 1996 a conference on Groups and Geometries took place in lovely Siena, Italy. It brought together experts and interested mathematicians from numerous countries. The scientific program centered around invited exposi­ tory lectures; there also were shorter research announcements, including talks by younger researchers. The conference concerned a broad range of topics in group theory and geometry, with emphasis on recent results and open problems. Special attention was drawn to the interplay between group-theoretic methods and geometric and combinatorial ones. Expanded versions of many of the talks appear in these Proceedings. This volume is intended to provide a stimulating collection of themes for a broad range of algebraists and geometers. Among those themes, represented within the conference or these Proceedings, are aspects of the following: 1. the classification of finite simple groups, 2. the structure and properties of groups of Lie type over finite and algebraically closed fields of f...

Finite fields and applications

CERN Document Server

Mullen, Gary L

2007-01-01

This book provides a brief and accessible introduction to the theory of finite fields and to some of their many fascinating and practical applications. The first chapter is devoted to the theory of finite fields. After covering their construction and elementary properties, the authors discuss the trace and norm functions, bases for finite fields, and properties of polynomials over finite fields. Each of the remaining chapters details applications. Chapter 2 deals with combinatorial topics such as the construction of sets of orthogonal latin squares, affine and projective planes, block designs, and Hadamard matrices. Chapters 3 and 4 provide a number of constructions and basic properties of error-correcting codes and cryptographic systems using finite fields. Each chapter includes a set of exercises of varying levels of difficulty which help to further explain and motivate the material. Appendix A provides a brief review of the basic number theory and abstract algebra used in the text, as well as exercises rel...

Application of the finite element method to the neutron transport equation

International Nuclear Information System (INIS)

Martin, W.R.

1976-01-01

This paper examines the theoretical and practical application of the finite element method to the neutron transport equation. It is shown that in principle the system of equations obtained by application of the finite element method can be solved with certain physical restrictions concerning the criticality of the medium. The convergence of this approximate solution to the exact solution with mesh refinement is examined, and a non-optical estimate of the convergence rate is obtained analytically. It is noted that the numerical results indicate a faster convergence rate and several approaches to obtain this result analytically are outlined. The practical application of the finite element method involved the development of a computer code capable of solving the neutron transport equation in 1-D plane geometry. Vacuum, reflecting, or specified incoming boundary conditions may be analyzed, and all are treated as natural boundary conditions. The time-dependent transport equation is also examined and it is shown that the application of the finite element method in conjunction with the Crank-Nicholson time discretization method results in a system of algebraic equations which is readily solved. Numerical results are given for several critical slab eigenvalue problems, including anisotropic scattering, and the results compare extremely well with benchmark results. It is seen that the finite element code is more efficient than a standard discrete ordinates code for certain problems. A problem with severe heterogeneities is considered and it is shown that the use of discontinuous spatial and angular elements results in a marked improvement in the results. Finally, time-dependent problems are examined and it is seen that the phenomenon of angular mode separation makes the numerical treatment of the transport equation in slab geometry a considerable challenge, with the result that the angular mesh has a dominant effect on obtaining acceptable solutions

On finite quantum field theories

International Nuclear Information System (INIS)

Rajpoot, S.; Taylor, J.G.

1984-01-01

The properties that make massless versions of N = 4 super Yang-Mills theory and a class of N = 2 supersymmetric theories finite are: (I) a universal coupling for the gauge and matter interactions, (II) anomaly-free representations to which the bosonic and fermionic matter belong, and (III) no charge renormalisation, i.e. β(g) = 0. It was conjectured that field theories constructed out of N = 1 matter multiplets are also finite if they too share the above properties. Explicit calculations have verified these theories to be finite up to two loops. The implications of the finiteness conditions for N = 1 finite field theories with SU(M) gauge symmetry are discussed. (orig.)

Finite element analysis of the cyclic indentation of bilayer enamel

International Nuclear Information System (INIS)

Jia, Yunfei; Xuan, Fu-zhen; Chen, Xiaoping; Yang, Fuqian

2014-01-01

Tooth enamel is often subjected to repeated contact and often experiences contact deformation in daily life. The mechanical strength of the enamel determines the biofunctionality of the tooth. Considering the variation of the rod arrangement in outer and inner enamel, we approximate enamel as a bilayer structure and perform finite element analysis of the cyclic indentation of the bilayer structure, to mimic the repeated contact of enamel during mastication. The dynamic deformation behaviour of both the inner enamel and the bilayer enamel is examined. The material parameters of the inner and outer enamel used in the analysis are obtained by fitting the finite element results with the experimental nanoindentation results. The penetration depth per cycle at the quasi-steady state is used to describe the depth propagation speed, which exhibits a two-stage power-law dependence on the maximum indentation load and the amplitude of the cyclic load, respectively. The continuous penetration of the indenter reflects the propagation of the plastic zone during cyclic indentation, which is related to the energy dissipation. The outer enamel serves as a protective layer due to its great resistance to contact deformation in comparison to the inner enamel. The larger equivalent plastic strain and lower stresses in the inner enamel during cyclic indentation, as calculated from the finite element analysis, indicate better crack/fracture resistance of the inner enamel. (paper)

Finite element analysis of the cyclic indentation of bilayer enamel

Science.gov (United States)

Jia, Yunfei; Xuan, Fu-zhen; Chen, Xiaoping; Yang, Fuqian

2014-04-01

Tooth enamel is often subjected to repeated contact and often experiences contact deformation in daily life. The mechanical strength of the enamel determines the biofunctionality of the tooth. Considering the variation of the rod arrangement in outer and inner enamel, we approximate enamel as a bilayer structure and perform finite element analysis of the cyclic indentation of the bilayer structure, to mimic the repeated contact of enamel during mastication. The dynamic deformation behaviour of both the inner enamel and the bilayer enamel is examined. The material parameters of the inner and outer enamel used in the analysis are obtained by fitting the finite element results with the experimental nanoindentation results. The penetration depth per cycle at the quasi-steady state is used to describe the depth propagation speed, which exhibits a two-stage power-law dependence on the maximum indentation load and the amplitude of the cyclic load, respectively. The continuous penetration of the indenter reflects the propagation of the plastic zone during cyclic indentation, which is related to the energy dissipation. The outer enamel serves as a protective layer due to its great resistance to contact deformation in comparison to the inner enamel. The larger equivalent plastic strain and lower stresses in the inner enamel during cyclic indentation, as calculated from the finite element analysis, indicate better crack/fracture resistance of the inner enamel.

Finite mixture models for the computation of isotope ratios in mixed isotopic samples

Science.gov (United States)

Koffler, Daniel; Laaha, Gregor; Leisch, Friedrich; Kappel, Stefanie; Prohaska, Thomas

2013-04-01

Finite mixture models have been used for more than 100 years, but have seen a real boost in popularity over the last two decades due to the tremendous increase in available computing power. The areas of application of mixture models range from biology and medicine to physics, economics and marketing. These models can be applied to data where observations originate from various groups and where group affiliations are not known, as is the case for multiple isotope ratios present in mixed isotopic samples. Recently, the potential of finite mixture models for the computation of 235U/238U isotope ratios from transient signals measured in individual (sub-)µm-sized particles by laser ablation - multi-collector - inductively coupled plasma mass spectrometry (LA-MC-ICPMS) was demonstrated by Kappel et al. [1]. The particles, which were deposited on the same substrate, were certified with respect to their isotopic compositions. Here, we focus on the statistical model and its application to isotope data in ecogeochemistry. Commonly applied evaluation approaches for mixed isotopic samples are time-consuming and are dependent on the judgement of the analyst. Thus, isotopic compositions may be overlooked due to the presence of more dominant constituents. Evaluation using finite mixture models can be accomplished unsupervised and automatically. The models try to fit several linear models (regression lines) to subgroups of data taking the respective slope as estimation for the isotope ratio. The finite mixture models are parameterised by: • The number of different ratios. • Number of points belonging to each ratio-group. • The ratios (i.e. slopes) of each group. Fitting of the parameters is done by maximising the log-likelihood function using an iterative expectation-maximisation (EM) algorithm. In each iteration step, groups of size smaller than a control parameter are dropped; thereby the number of different ratios is determined. The analyst only influences some control

The adjoint string at finite temperature

International Nuclear Information System (INIS)

Damgaard, P.H.

1986-10-01

Expectations for the behavior of the adjoint string at finite temperature are presented. In the Migdal-Kadanoff approximation a real-space renormalization group study of the effective Polyakov like action predicts a deconfinement-like crossover for adjoint sources at a temperature slightly below the deconfinement temperature of fundamental sources. This prediction is compared with a Monte Carlo simulation of SU(2) lattice gauge theory on an 8 3 x2 lattice. (orig.)

Finite size scaling theory

International Nuclear Information System (INIS)

Rittenberg, V.

1983-01-01

Fischer's finite-size scaling describes the cross over from the singular behaviour of thermodynamic quantities at the critical point to the analytic behaviour of the finite system. Recent extensions of the method--transfer matrix technique, and the Hamiltonian formalism--are discussed in this paper. The method is presented, with equations deriving scaling function, critical temperature, and exponent v. As an application of the method, a 3-states Hamiltonian with Z 3 global symmetry is studied. Diagonalization of the Hamiltonian for finite chains allows one to estimate the critical exponents, and also to discover new phase transitions at lower temperatures. The critical points lambda, and indices v estimated for finite-scaling are given

Effect of black silicon disordered structures distribution on its wideband reduced reflectance

International Nuclear Information System (INIS)

Saab, D Abi; Mostarshedi, S; Basset, P; Protat, S; Angelescu, D; Richalot, E

2014-01-01

We present a simple and accurate model for the reflectance simulation of black silicon (BSi) based on the finite element method (FEM). Normalized-root-mean-square error (NRMSE) with experimental measurements below 0.25% has been obtained for wavelength range between 450 and 950 nm. The model is made of a four basic shape cell whose dimensions are extracted from an accurate topography of the BSi obtained by FIB-SEM tomography. Additional BSi modelling techniques were studied, which take into account the BSi irregular topography, demonstrating an important influence of the local structure height variation in the BSi surface spectral reflectance. (paper)

$\\delta$-Expansion at Finite Temperature

OpenAIRE

Ramos, Rudnei O.

1996-01-01

We apply the $\\delta$-expansion perturbation scheme to the $\\lambda \\phi^{4}$ self-interacting scalar field theory in 3+1 D at finite temperature. In the $\\delta$-expansion the interaction term is written as $\\lambda (\\phi^{2})^{ 1 + \\delta}$ and $\\delta$ is considered as the perturbation parameter. We compute within this perturbative approach the renormalized mass at finite temperature at a finite order in $\\delta$. The results are compared with the usual loop-expansion at finite temperature.

Finite spatial volume approach to finite temperature field theory

International Nuclear Information System (INIS)

Weiss, Nathan

1981-01-01

A relativistic quantum field theory at finite temperature T=β -1 is equivalent to the same field theory at zero temperature but with one spatial dimension of finite length β. This equivalence is discussed for scalars, for fermions, and for gauge theories. The relationship is checked for free field theory. The translation of correlation functions between the two formulations is described with special emphasis on the nonlocal order parameters of gauge theories. Possible applications are mentioned. (auth)

Evaluating a nursing erasmus exchange experience: Reflections on the use and value of the Nominal Group Technique for evaluation.

Science.gov (United States)

Cunningham, Sheila

2017-09-01

This paper discusses the use of Nominal Group Technique (NGT) for European nursing exchange evaluation at one university. The NGT is a semi-quantitative evaluation method derived from the Delphi method popular in the 1970s and 1980s. The NGT was modified from the traditional version retaining the structured cycles and but adding a broader group discussion. The NGT had been used for 2 successive years but required analysis and evaluation itself for credibility and 'fit' for purpose which is presented here. It aimed to explore nursing students' exchange experiences and aid programme development futures exchanges and closure from exchange. Results varied for the cohorts and students as participants enthusiastically engaged generating ample data which they ranked and categorised collectively. Evaluation of the NGT itself was two fold: by the programme team who considered purpose, audience, inclusivity, context and expertise. Secondly, students were asked for their thoughts using a graffiti board. Students avidly engaged with NGT but importantly also reported an effect from the process itself as an opportunity to reflect and share their experiences. The programme team concluded the NGT offered a credible evaluation tool which made use of authentic student voice and offered interactive group processes. Pedagogially, it enabled active reflection thus aiding reorientation back to the United Kingdom and awareness of 'transformative' consequences of their exchange experiences. Copyright © 2017 Elsevier Ltd. All rights reserved.

Guided wave radiation in a finite-sized metallic or composite plate-like structure for its nondestructive testing

International Nuclear Information System (INIS)

Stevenin, Mathilde

2016-01-01

Different models are developed to provide generic tools for simulating nondestructive methods relying on elastic guided waves applied to metallic or composite plates. Various inspection methods of these structures exist or are under study. Most of them make use of ultrasonic sources of finite size; all are sensitive to reflection phenomena resulting from the finite size of the monitored objects. The developed models deal with transducer diffraction effects and edge reflection. As the interpretation of signals measured in guided wave inspection often uses the concept of modes, the models themselves are explicitly modal. The case of isotropic plates (metal) and anisotropic (multilayer composites) are considered; a general approach under the stationary phase approximation allows us to consider all the cases of interest. For the first, the validity of a Fraunhofer-like approximation leads to a very efficient computation of the direct and reflected fields radiated by a source. For the second, special attention is paid to the treatment of caustics. The stationary phase approximation being difficult to generalize, a model (so-called 'pencil model') of more geometrical nature is proposed with a high degree of genericity. It chains terms of isotropic or anisotropic propagation and terms of interaction with a boundary. The equivalence of the stationary phase approximation and the pencil model is demonstrated in the case of the radiation and reflection in an isotropic plate, for which an experimental validation is proceeded. (author) [fr

Employing finite-state machines in data integrity problems

Directory of Open Access Journals (Sweden)

Malikov Andrey

2016-01-01

Full Text Available This paper explores the issue of group integrity of tuple subsets regarding corporate integrity constraints in relational databases. A solution may be found by applying the finite-state machine theory to guarantee group integrity of data. We present a practical guide to coding such an automaton. After creating SQL queries to manipulate data and control its integrity for real data domains, we study the issue of query performance, determine the level of transaction isolation, and generate query plans.

Linear deformations of discrete groups and constructions of multivalued groups

International Nuclear Information System (INIS)

Yagodovskii, Petr V

2000-01-01

We construct deformations of discrete multivalued groups described as special deformations of their group algebras in the class of finite-dimensional associative algebras. We show that the deformations of ordinary groups producing multivalued groups are defined by cocycles with coefficients in the group algebra of the original group and obtain classification theorems on these deformations. We indicate a connection between the linear deformations of discrete groups introduced in this paper and the well-known constructions of multivalued groups. We describe the manifold of three-dimensional associative commutative algebras with identity element, fixed basis, and a constant number of values. The group algebras of n-valued groups of order three (three-dimensional n-group algebras) form a discrete set in this manifold

Finiteness Marking in Boys with Fragile X Syndrome

Science.gov (United States)

Sterling, Audra M.; Rice, Mabel L.; Warren, Steven F.

2012-01-01

Purpose: The current study investigated finiteness marking (e.g., he walk "s", he walk "ed") in boys with fragile X syndrome (FXS); the boys were grouped based on receptive vocabulary (i.e., borderline, impaired). Method: Twenty-one boys with the full mutation of fragile X, between the ages of 8 and 16 years participated. The…

Neutron Transport in Finite Random Media with Pure-Triplet Scattering

International Nuclear Information System (INIS)

Sallaha, M.; Hendi, A.A.

2008-01-01

The solution of the one-speed neutron transport equation in a finite slab random medium with pure-triplet anisotropic scattering is studied. The stochastic medium is assumed to consist of two randomly mixed immiscible fluids. The cross section and the scattering kernel are treated as discrete random variables, which obey the same statistics as Markovian processes and exponential chord length statistics. The medium boundaries are considered to have specular reflectivities with angular-dependent externally incident flux. The deterministic solution is obtained by using Pomraning-Eddington approximation. Numerical results are calculated for the average reflectivity and average transmissivity for different values of the single scattering albedo and varying the parameters which characterize the random medium. Compared to the results obtained by Adams et al. in case of isotropic scattering that based on the Monte Carlo technique, it can be seen that we have good comparable data

Some aspects of the quality assurance of personnel carrying out finite element analysis

International Nuclear Information System (INIS)

Dickenson, P.W.

1990-01-01

In this paper, the need to assess the competence of personnel carrying out finite element analysis is emphasised. In carrying out its regulatory role on behalf of the Health and Safety Executive, the Nuclear Installations Inspectorate (NII) must be satisfied that appropriate standards are developed and maintained by the licensee. Since finite element methods have an important bearing on the acceptance of a safety case, it follows that relevant codes should be adequately validated and the personnel applying the code should be competent. Attention is drawn to the work of the Quality Assurance Working Group of the National Agency for Finite Element Methods and Standards (NAFEMS) who are active in this area. The paper also considers the methods that are available to assess the competence of personnel engaged in finite element methods. (author)

Finite-dimensional calculus

International Nuclear Information System (INIS)

Feinsilver, Philip; Schott, Rene

2009-01-01

We discuss topics related to finite-dimensional calculus in the context of finite-dimensional quantum mechanics. The truncated Heisenberg-Weyl algebra is called a TAA algebra after Tekin, Aydin and Arik who formulated it in terms of orthofermions. It is shown how to use a matrix approach to implement analytic representations of the Heisenberg-Weyl algebra in univariate and multivariate settings. We provide examples for the univariate case. Krawtchouk polynomials are presented in detail, including a review of Krawtchouk polynomials that illustrates some curious properties of the Heisenberg-Weyl algebra, as well as presenting an approach to computing Krawtchouk expansions. From a mathematical perspective, we are providing indications as to how to implement infinite terms Rota's 'finite operator calculus'.

Application of the finite element method to neutronics problems with inhomogeneous boundray conditions

International Nuclear Information System (INIS)

Yoo, K.J.

1982-01-01

The albedo boundary conditions are incorporated into the finite element method using bicubic Hermite element functions in order to reduce the computer memory and computation time in two-group diffusion calculations by excluding the reflector regions in computation space. The basis functions at the core-reflector interfaces are newly established to satisfy the albedo boundary conditions, and then the ''weak'' form of two-group diffusion equations is discretized using the principle of the weighted residual method in combination with the Galerkin approximation. The discretized two-group diffusion equation is then solved by the Gaussian elimination method with the scaled column pivoting algorithm in one-dimensional problem and Gauss-Seidel method in two-dimensional problem. Prior to the application of the method to two-group diffusion problems, the same method is applied to the one-speed neutron transport equation in a bare slab reactor with the vacuum boundary condition to confirm its usefulness in the diffusion calculations. To investigate the applicability of our diffusion method, several numerical calculations are performed: two-dimensional IAEA benchmark problem and two-dimensional ZION problem. The results are compared with the available results from the conventional finite difference and other finite element methods. If the albedo values are appropriately adjusted, our results of the two-dimensional IAEA benchmark problem are agreed within 0.002% of ksub(eff) with the fine mesh PDQ results. Comparing with CITATION results, one-eighth of core memory and one-fifteenth of computing time are required to obtain the same accuracy even though no acceleration technique is used in the present case. Also, it is found that the results are comparable with the other finite element results. However, no significant saving is obtained in computation time comparing with the other finite element results, where the reflector regions are explicity included. This mainly comes from

Finite-element-model updating using computational intelligence techniques applications to structural dynamics

CERN Document Server

Marwala, Tshilidzi

2010-01-01

Finite element models (FEMs) are widely used to understand the dynamic behaviour of various systems. FEM updating allows FEMs to be tuned better to reflect measured data and may be conducted using two different statistical frameworks: the maximum likelihood approach and Bayesian approaches. Finite Element Model Updating Using Computational Intelligence Techniques applies both strategies to the field of structural mechanics, an area vital for aerospace, civil and mechanical engineering. Vibration data is used for the updating process. Following an introduction a number of computational intelligence techniques to facilitate the updating process are proposed; they include: • multi-layer perceptron neural networks for real-time FEM updating; • particle swarm and genetic-algorithm-based optimization methods to accommodate the demands of global versus local optimization models; • simulated annealing to put the methodologies into a sound statistical basis; and • response surface methods and expectation m...

Accuracy of specimen-specific nonlinear finite element analysis for evaluation of distal radius strength in cadaver material.

Science.gov (United States)

Matsuura, Yusuke; Kuniyoshi, Kazuki; Suzuki, Takane; Ogawa, Yasufumi; Sukegawa, Koji; Rokkaku, Tomoyuki; Takahashi, Kazuhisa

2014-11-01

Distal radius fracture, which often occurs in the setting of osteoporosis, can lead to permanent deformity and disability. Great effort has been directed toward developing noninvasive methods for evaluating the distal radius strength, with the goal of assessing fracture risk. The aim of this study was to evaluate distal radius strength using a finite element model and to gauge the accuracy of finite element model measurement using cadaver material. Ten wrists were obtained from cadavers with a mean age of 89.5 years at death. CT images of each wrist in an extended position were obtained. CT-based finite element models were prepared with Mechanical Finder software. Fracture on the models was simulated by applying a mechanical load to the palm in a direction parallel to the forearm axis, after which the fracture load and the site at which the fracture began were identified. For comparison, the wrists were fractured using a universal testing machine and the fracture load and the site of fracture were identified. The fracture load was 970.9 N in the finite element model group and 990.0 N in the actual measurement group. The site of the initial fracture was extra-articular to the distal radius in both groups. The finite element model was predictive for distal radius fracture when compared to the actual measurement. In this study, a finite element model for evaluation of distal radius strength was validated and can be used to predict fracture risk. We conclude that a finite element model is useful for the evaluation of distal radius strength. Knowing distal radius strength might avoid distal radius fracture because appropriate antiosteoporotic treatment can be initiated.

Do writing and storytelling skill influence assessment of reflective ability in medical students' written reflections?

Science.gov (United States)

Aronson, Louise; Niehaus, Brian; DeVries, Charlie D; Siegel, Jennifer R; O'Sullivan, Patricia S

2010-10-01

Increasingly, students are asked to write reflections as part of their medical education, but some question the influence of other factors on the evaluation of these reflections. In this pilot study, the investigators determined whether scores from a validated rubric to measure reflective ability were affected by irrelevant variance resulting from writing or storytelling ability. Students in clerkships wrote reflections on professionalism. All were given identical prompts, with half receiving additional structured guidelines on reflection. Sixty reflections, 30 from each group, were randomly chosen and scored for reflection, writing, and storytelling by trained raters using validated rubrics. There was no correlation between reflection and either writing (r = 0.049, P = .35) or storytelling (r = 0.14, P = .13). The guidelines increased reflection, but not writing or storytelling scores. Reflection is a distinct construct unaffected by learners' writing or storytelling skills. These findings support reflective ability as a distinct skill.

The unit group of group algebra $F_qSL(2;Z_3$

Directory of Open Access Journals (Sweden)

Swati Maheshwari

2016-01-01

Full Text Available Let $\\F_q$ be a finite field of characteristic $p$ having $q$ elements, where $q = p^k$ and $p\\ge 5$. Let $ SL(2,\\Z_3$ be the special linear group of $2\\times2$ matrices with determinant $1$ over $\\Z_3$. In this note we establish the structure of the unit group of $\\F_q SL(2,\\Z_3$.

Delocalized SYZ mirrors and confronting top-down SU(3)-structure holographic meson masses at finite g and Nc with P(article) D(ata) G(roup) values

International Nuclear Information System (INIS)

Yadav, Vikas; Sil, Karunava; Misra, Aalok

2017-01-01

Meson spectroscopy at finite gauge coupling - whereat any perturbative QCD computation would break down - and finite number of colors, from a top-down holographic string model, has thus far been entirely missing in the literature. This paper fills this gap. Using the delocalized type IIA SYZ mirror (with SU(3) structure) of the holographic type IIB dual of large-N thermal QCD of Mia et al. (Nucl Phys B 839:187. arXiv:0902.1540 [hep-th], 2010) as constructed in Dhuria and Misra (JHEP 1311:001. arXiv:1306.4339 [hep-th], 2013) at finite coupling and number of colors (N c = number of D5(D5)-branes wrapping a vanishing two-cycle in the top-down holographic construct of Mia et al. (Nucl Phys B 839:187. arXiv:0902.1540 [hep-th], 2010) = O(1) in the IR in the MQGP limit of Dhuria and Misra (JHEP 1311:001. arXiv:1306.4339 [hep-th], 2013) at the end of a Seiberg-duality cascade), we obtain analytical (not just numerical) expressions for the vector and scalar meson spectra and compare our results with previous calculations of Sakai and Sugimoto (Prog Theor Phys 113:843. doi:10.1143/PTP.113.843 arXiv:hep-th/0412141, 2005) and Dasgupta et al. (JHEP 1507:122. doi:10.1007/JHEP07(2015)122 arXiv:1409.0559 [hep-th], 2015), and we obtain a closer match with the Particle Data Group (PDG) results of Olive et al. (Particle Data Group) (Chin Phys C 38:090001, 2014). Through explicit computations, we verify that the vector and scalar meson spectra obtained by the gravity dual with a black hole for all temperatures (small and large) are nearly isospectral with the spectra obtained by a thermal gravity dual valid for only low temperatures; the isospectrality is much closer for vector mesons than scalar mesons. The black-hole gravity dual (with a horizon radius smaller than the deconfinement scale) also provides the expected large-N suppressed decrease in vector meson mass with increase of temperature. (orig.)

Computations of finite temperature QCD with the pseudofermion method

International Nuclear Information System (INIS)

Fucito, F.; Solomon, S.

1985-01-01

The authors discuss the phase diagram of finite temperature QCD as it is obtained including the effects of dynamical quarks by the pseudofermion method. They compare their results with the results obtained by other groups and comment on the actual state of the art for these kind of computations

How to use the Fast Fourier Transform in Large Finite Fields

OpenAIRE

Petersen, Petur Birgir

2011-01-01

The article contents suggestions on how to perform the Fast Fourier Transform over Large Finite Fields. The technique is to use the fact that the multiplicative groups of specific prime fields are surprisingly composite.

Bit-string physics a finite and discrete approach to natural philosophy

CERN Document Server

Noyes, H Pierre

2001-01-01

We could be on the threshold of a scientific revolution. Quantum mechanics is based on unique, finite, and discrete events. General relativity assumes a continuous, curved space-time. Reconciling the two remains the most fundamental unsolved scientific problem left over from the last century. The papers of H Pierre Noyes collected in this volume reflect one attempt to achieve that unification by replacing the continuum with the bit-string events of computer science. Three principles are used: physics can determine whether two quantities are the same or different; measurement can tell something

Group theory I essentials

CERN Document Server

Milewski, Emil G

2012-01-01

REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Group Theory I includes sets and mapping, groupoids and semi-groups, groups, isomorphisms and homomorphisms, cyclic groups, the Sylow theorems, and finite p-groups.

Finite elements and approximation

CERN Document Server

Zienkiewicz, O C

2006-01-01

A powerful tool for the approximate solution of differential equations, the finite element is extensively used in industry and research. This book offers students of engineering and physics a comprehensive view of the principles involved, with numerous illustrative examples and exercises.Starting with continuum boundary value problems and the need for numerical discretization, the text examines finite difference methods, weighted residual methods in the context of continuous trial functions, and piecewise defined trial functions and the finite element method. Additional topics include higher o

All unitary ray representations of the conformal group SU(2,2) with positive energy

International Nuclear Information System (INIS)

Mack, G.

1975-12-01

We find all those unitary irreducible representations of the infinitely - sheeted covering group G tilde of the conformal group SU(2,2)/Z 4 which have positive energy P 0 >= O. They are all finite component field representations and are labelled by dimension d and a finite dimensional irreducible representation (j 1 , j 2 ) of the Lorentz group SL(2C). They all decompose into a finite number of unitary irreducible representations of the Poincare subgroup with dilations. (orig.) [de

On conjugacy growth of linear groups

OpenAIRE

Breuillard, Emmanuel; de Cornulier, Yves; Lubotzky, Alexander; Meiri, Chen

2011-01-01

We investigate the conjugacy growth of finitely generated linear groups. We show that finitely generated non-virtually-solvable subgroups of GL_d have uniform exponential conjugacy growth and in fact that the number of distinct polynomials arising as characteristic polynomials of the elements of the ball of radius n for the word metric has exponential growth rate bounded away from 0 in terms of the dimension d only.

Finite element modelling of fibre Bragg grating strain sensors and experimental validation

Science.gov (United States)

Malik, Shoaib A.; Mahendran, Ramani S.; Harris, Dee; Paget, Mark; Pandita, Surya D.; Machavaram, Venkata R.; Collins, David; Burns, Jonathan M.; Wang, Liwei; Fernando, Gerard F.

2009-03-01

Fibre Bragg grating (FBG) sensors continue to be used extensively for monitoring strain and temperature in and on engineering materials and structures. Previous researchers have also developed analytical models to predict the loadtransfer characteristics of FBG sensors as a function of applied strain. The general properties of the coating or adhesive that is used to surface-bond the FBG sensor to the substrate has also been modelled using finite element analysis. In this current paper, a technique was developed to surface-mount FBG sensors with a known volume and thickness of adhesive. The substrates used were aluminium dog-bone tensile test specimens. The FBG sensors were tensile tested in a series of ramp-hold sequences until failure. The reflected FBG spectra were recorded using a commercial instrument. Finite element analysis was performed to model the response of the surface-mounted FBG sensors. In the first instance, the effect of the mechanical properties of the adhesive and substrate were modelled. This was followed by modelling the volume of adhesive used to bond the FBG sensor to the substrate. Finally, the predicted values obtained via finite element modelling were correlated to the experimental results. In addition to the FBG sensors, the tensile test specimens were instrumented with surface-mounted electrical resistance strain gauges.

"Understanding my ALS". Experiences and reflections of persons with amyotrophic lateral sclerosis and relatives on participation in peer group rehabilitation.

Science.gov (United States)

Madsen, Louise Sofia; Jeppesen, Jørgen; Handberg, Charlotte

2018-01-26

The aim of this study was to gain insight into experiences and reflections of persons with amyotrophic lateral sclerosis and relatives concerning the peer group rehabilitation programme "More Life - Less Illness". This qualitative study used the Interpretive Description methodology with Symbolic Interactionism as the analytical framework. Eighteen programme participants representing persons with amyotrophic lateral sclerosis (n = 8) and relatives (n = 10) were included. Data consisted of individual interviews and participant observation. The analysis revealed two categorical themes, "Sense of Community Building" and "Understanding my ALS", which represented the participants' experiences and reflections on peer group rehabilitation. Through the analysis, it became apparent that "Sense of Community Building" gave rise to an increased and personalised understanding of amyotrophic lateral sclerosis among the participants. As a part of the continuous processing of the knowledge gained, "Facing Facts" and "Retaining Normality" appeared as subthemes regarding the participants' ability to live a less dependent and more meaningful life. This study of peer group rehabilitation for persons with amyotrophic lateral sclerosis and relatives indicates that programme participation leads to positive experiences in terms of living a shared meaningful life despite severe disability. The findings may guide practice to develop longitudinal peer group rehabilitation programmes with joint inclusion of persons with amyotrophic lateral sclerosis and relatives. Implications for Rehabilitation Peer group rehabilitation may facilitate an increased and personalised understanding of what it means to live with amyotrophic lateral sclerosis. A programme design with six months of sequential sessions enables a continuous processing of shared experiences and gained knowledge. Joint participation of persons with amyotrophic lateral sclerosis and their relatives supports both their internal

Parallel iterative procedures for approximate solutions of wave propagation by finite element and finite difference methods

Energy Technology Data Exchange (ETDEWEB)

Kim, S. [Purdue Univ., West Lafayette, IN (United States)

1994-12-31

Parallel iterative procedures based on domain decomposition techniques are defined and analyzed for the numerical solution of wave propagation by finite element and finite difference methods. For finite element methods, in a Lagrangian framework, an efficient way for choosing the algorithm parameter as well as the algorithm convergence are indicated. Some heuristic arguments for finding the algorithm parameter for finite difference schemes are addressed. Numerical results are presented to indicate the effectiveness of the methods.

Partial Actions, Paradoxicality and Topological full Groups

DEFF Research Database (Denmark)

Scarparo, Eduardo

uniform Roe algebra is finite. In Article C, we analyze the C*-algebra generated by the Koopman representation of a topological full group, showing, in particular, that it is not AF andhas real rank zero. We also prove that if G is a finitely generated, elementary amenable group, and C*(G) has real rank......We study how paradoxicality properties affect the way groups partially acton topological spaces and C*-algebras. We also investigate the real rank zero and AF properties for certain classes of group C*-algebras. Specifically, in article A, we characterize supramenable groups in terms of existence...... of invariant probability measures for partial actions on compact Hausdorff spaces and existence of tracial states on partial crossed products. These characterizations show that, in general, one cannot decompose a partial crossed product of a C*-algebra by a semidirect product of groups as two iterated...

Generalizations of the BMS group and results

International Nuclear Information System (INIS)

Melas, E

2006-01-01

The ordinary Bondi-Metzner-Sachs (BMS) group B is the common asymptotic symmetry group of all radiating, asymptotically flat, Lorentzian space-times. As such, B is the best candidate for the universal symmetry group of General Relativity. However, in studying quantum gravity, space-times with signatures other than the usual Lorentzian one, and complex space-times, are frequently considered. Generalisations of B appropriate to these other signatures have been defined earlier. In particular, the generalization B(2, 2) appropriate to the ultrahyperbolic signature (+, +, -, -) has been described in detail, and the study of its irreducible unitary representations (IRs) has been initiated. The infinite little groups of B(2, 2) have been given explicitly but its finite little groups have only been partially described. All the information needed in order to construct the finite little groups is given. Possible connections with gravitational instantons are being put forward

Magnetoanisotropic spin-triplet Andreev reflection in ferromagnet-Ising superconductor junctions

Science.gov (United States)

Lv, Peng; Zhou, Yan-Feng; Yang, Ning-Xuan; Sun, Qing-Feng

2018-04-01

We theoretically study the electronic transport through a ferromagnet-Ising superconductor junction. A tight-binding Hamiltonian describing the Ising superconductor is presented. Then by combining the nonequilibrium Green's function method, the expressions of Andreev reflection coefficient and conductance are obtained. A strong magnetoanisotropic spin-triplet Andreev reflection is shown, and the magnetoanisotropic period is π instead of 2 π as in the conventional magnetoanisotropic system. We demonstrate a significant increase of the spin-triplet Andreev reflection for the single-band Ising superconductor. Furthermore, the dependence of the Andreev reflection on the incident energy and incident angle are also investigated. A complete Andreev reflection can occur when the incident energy is equal to the superconducting gap, regardless of the Fermi energy (spin polarization) of the ferromagnet. For the suitable oblique incidence, the spin-triplet Andreev reflection can be strongly enhanced. In addition, the conductance spectroscopies of both zero bias and finite bias are studied, and the influence of gate voltage, exchange energy, and spin-orbit coupling on the conductance spectroscopy are discussed in detail. The conductance exhibits a strong magnetoanisotropy with period π as the Andreev reflection coefficient. When the magnetization direction is parallel to the junction plane, a large conductance peak always emerges at the superconducting gap. This work offers a comprehensive and systematic study of the spin-triplet Andreev reflection and has an underlying application of π -periodic spin valve in spintronics.

Massively Parallel Finite Element Programming

KAUST Repository

Heister, Timo; Kronbichler, Martin; Bangerth, Wolfgang

2010-01-01

Today's large finite element simulations require parallel algorithms to scale on clusters with thousands or tens of thousands of processor cores. We present data structures and algorithms to take advantage of the power of high performance computers in generic finite element codes. Existing generic finite element libraries often restrict the parallelization to parallel linear algebra routines. This is a limiting factor when solving on more than a few hundreds of cores. We describe routines for distributed storage of all major components coupled with efficient, scalable algorithms. We give an overview of our effort to enable the modern and generic finite element library deal.II to take advantage of the power of large clusters. In particular, we describe the construction of a distributed mesh and develop algorithms to fully parallelize the finite element calculation. Numerical results demonstrate good scalability. © 2010 Springer-Verlag.

Massively Parallel Finite Element Programming

KAUST Repository

Heister, Timo

2010-01-01

Today\\'s large finite element simulations require parallel algorithms to scale on clusters with thousands or tens of thousands of processor cores. We present data structures and algorithms to take advantage of the power of high performance computers in generic finite element codes. Existing generic finite element libraries often restrict the parallelization to parallel linear algebra routines. This is a limiting factor when solving on more than a few hundreds of cores. We describe routines for distributed storage of all major components coupled with efficient, scalable algorithms. We give an overview of our effort to enable the modern and generic finite element library deal.II to take advantage of the power of large clusters. In particular, we describe the construction of a distributed mesh and develop algorithms to fully parallelize the finite element calculation. Numerical results demonstrate good scalability. © 2010 Springer-Verlag.

Computing nilpotent quotients in finitely presented Lie rings

Directory of Open Access Journals (Sweden)

Csaba Schneider

1997-12-01

Full Text Available A nilpotent quotient algorithm for finitely presented Lie rings over Z (and Q is described. The paper studies the graded and non-graded cases separately. The algorithm computes the so-called nilpotent presentation for a finitely presented, nilpotent Lie ring. A nilpotent presentation consists of generators for the abelian group and the products expressed as linear combinations for pairs formed by generators. Using that presentation the word problem is decidable in L. Provided that the Lie ring L is graded, it is possible to determine the canonical presentation for a lower central factor of L. Complexity is studied and it is shown that optimising the presentation is NP-hard. Computational details are provided with examples, timing and some structure theorems obtained from computations. Implementation in C and GAP interface are available.

Property ($T$) for groups graded by root systems

CERN Document Server

Ershov, Mikhail; Kassabov, Martin

2017-01-01

The authors introduce and study the class of groups graded by root systems. They prove that if \\Phi is an irreducible classical root system of rank \\geq 2 and G is a group graded by \\Phi, then under certain natural conditions on the grading, the union of the root subgroups is a Kazhdan subset of G. As the main application of this theorem the authors prove that for any reduced irreducible classical root system \\Phi of rank \\geq 2 and a finitely generated commutative ring R with 1, the Steinberg group {\\mathrm St}_{\\Phi}(R) and the elementary Chevalley group \\mathbb E_{\\Phi}(R) have property (T). They also show that there exists a group with property (T) which maps onto all finite simple groups of Lie type and rank \\geq 2, thereby providing a "unified" proof of expansion in these groups.

Convergence rates and finite-dimensional approximations for nonlinear ill-posed problems involving monotone operators in Banach spaces

International Nuclear Information System (INIS)

Nguyen Buong.

1992-11-01

The purpose of this paper is to investigate convergence rates for an operator version of Tikhonov regularization constructed by dual mapping for nonlinear ill-posed problems involving monotone operators in real reflective Banach spaces. The obtained results are considered in combination with finite-dimensional approximations for the space. An example is considered for illustration. (author). 15 refs

Accuracy of spectral and finite difference schemes in 2D advection problems

DEFF Research Database (Denmark)

Naulin, V.; Nielsen, A.H.

2003-01-01

In this paper we investigate the accuracy of two numerical procedures commonly used to solve 2D advection problems: spectral and finite difference (FD) schemes. These schemes are widely used, simulating, e.g., neutral and plasma flows. FD schemes have long been considered fast, relatively easy...... that the accuracy of FD schemes can be significantly improved if one is careful in choosing an appropriate FD scheme that reflects conservation properties of the nonlinear terms and in setting up the grid in accordance with the problem....

Harmonic analysis and global solvability of a differential operator invariant on motion groups and semi-simple Lie groups

International Nuclear Information System (INIS)

El-Hussein, K.

1991-08-01

Let V be a real finite dimensional vector space and let K be a connected compact Lie group, which acts on V by means of a continuous linear representation ρ. Let G=V x p K be the motion group which is the semi-direct product of V by K and let P be an invariant differential operator on G. In this paper we give a necessary and sufficient condition for the global solvability of P on G. Now let G be a connected semi-simple Lie group with finite centre and let P be an invariant differential operator on G. We give also a necessary and sufficient condition for the global solvability of P on G. (author). 8 refs

Introduction to finite temperature and finite density QCD

International Nuclear Information System (INIS)

Kitazawa, Masakiyo

2014-01-01

It has been pointed out that QCD (Quantum Chromodynamics) in the circumstances of medium at finite temperature and density shows numbers of phenomena similar to the characteristics of solid state physics, e.g. phase transitions. In the past ten years, the very high temperature and density matter came to be observed experimentally at the heavy ion collisions. At the same time, the numerical QCD analysis at finite temperature and density attained quantitative level analysis possible owing to the remarkable progress of computers. In this summer school lecture, it has been set out to give not only the recent results, but also the spontaneous breaking of the chiral symmetry, the fundamental theory of finite temperature and further expositions as in the following four sections. The first section is titled as 'Introduction to Finite Temperature and Density QCD' with subsections of 1.1 standard model and QCD, 1.2 phase transition and phase structure of QCD, 1.3 lattice QCD and thermodynamic quantity, 1.4 heavy ion collision experiments, and 1.5 neutron stars. The second one is 'Equilibrium State' with subsections of 2.1 chiral symmetry, 2.2 vacuum state: BCS theory, 2.3 NJL (Nambu-Jona-Lasinio) model, and 2.4 color superconductivity. The third one is 'Static fluctuations' with subsections of 3.1 fluctuations, 3.2 moment and cumulant, 3.3 increase of fluctuations at critical points, 3.4 analysis of fluctuations by lattice QCD and Taylor expansion, and 3.5 experimental exploration of QCD phase structure. The fourth one is 'Dynamical Structure' with 4.1 linear response theory, 4.2 spectral functions, 4.3 Matsubara function, and 4.4 analyses of dynamical structure by lattice QCD. (S. Funahashi)

Summary Report of Working Group 2: Computation

International Nuclear Information System (INIS)

Stoltz, P. H.; Tsung, R. S.

2009-01-01

The working group on computation addressed three physics areas: (i) plasma-based accelerators (laser-driven and beam-driven), (ii) high gradient structure-based accelerators, and (iii) electron beam sources and transport [1]. Highlights of the talks in these areas included new models of breakdown on the microscopic scale, new three-dimensional multipacting calculations with both finite difference and finite element codes, and detailed comparisons of new electron gun models with standard models such as PARMELA. The group also addressed two areas of advances in computation: (i) new algorithms, including simulation in a Lorentz-boosted frame that can reduce computation time orders of magnitude, and (ii) new hardware architectures, like graphics processing units and Cell processors that promise dramatic increases in computing power. Highlights of the talks in these areas included results from the first large-scale parallel finite element particle-in-cell code (PIC), many order-of-magnitude speedup of, and details of porting the VPIC code to the Roadrunner supercomputer. The working group featured two plenary talks, one by Brian Albright of Los Alamos National Laboratory on the performance of the VPIC code on the Roadrunner supercomputer, and one by David Bruhwiler of Tech-X Corporation on recent advances in computation for advanced accelerators. Highlights of the talk by Albright included the first one trillion particle simulations, a sustained performance of 0.3 petaflops, and an eight times speedup of science calculations, including back-scatter in laser-plasma interaction. Highlights of the talk by Bruhwiler included simulations of 10 GeV accelerator laser wakefield stages including external injection, new developments in electromagnetic simulations of electron guns using finite difference and finite element approaches.

Finite element computational fluid mechanics

International Nuclear Information System (INIS)

Baker, A.J.

1983-01-01

This book analyzes finite element theory as applied to computational fluid mechanics. It includes a chapter on using the heat conduction equation to expose the essence of finite element theory, including higher-order accuracy and convergence in a common knowledge framework. Another chapter generalizes the algorithm to extend application to the nonlinearity of the Navier-Stokes equations. Other chapters are concerned with the analysis of a specific fluids mechanics problem class, including theory and applications. Some of the topics covered include finite element theory for linear mechanics; potential flow; weighted residuals/galerkin finite element theory; inviscid and convection dominated flows; boundary layers; parabolic three-dimensional flows; and viscous and rotational flows

Group as social microcosm: Within-group interpersonal style is congruent with outside group relational tendencies.

Science.gov (United States)

Goldberg, Simon B; Hoyt, William T

2015-06-01

The notion that individuals' interpersonal behaviors in the context of therapy reflects their interpersonal behaviors outside of therapy is a fundamental hypothesis underlying numerous systems of psychotherapy. The social microcosm hypothesis, in particular, claims the interpersonal therapy group becomes a reflection of group members' general tendencies, and can thus be used as information about members' interpersonal functioning as well as an opportunity for learning and behavior change. The current study tested this hypothesis using data drawn from 207 individuals participating in 22 interpersonal process groups. Ratings were made on 2 key interpersonal domains (Dominance and Affiliation) at baseline and at Weeks 2, 5, and 8 of the group. Two-level multilevel models (with participants nested within groups) were used to account for the hierarchical structure, and the social relations model (SRM; Kenny, 1994) was used to estimate peer ratings (target effects in SRM) unconfounded with rater bias. Participants showed consensus at all time points during the interpersonal process groups on one another's levels of dominance and affiliation. In addition, self- and peer ratings were stable across time and correlated with one another. Importantly, self-ratings made prior to group significantly predicted ratings (self- and peer) made within the group, with effect sizes within the medium range. Taken together, these results provide robust support for the social microcosm hypothesis and the conjecture that interpersonal style within-group therapy is reflective of broader interpersonal tendencies. (c) 2015 APA, all rights reserved).

Designs and finite geometries

CERN Document Server

1996-01-01

Designs and Finite Geometries brings together in one place important contributions and up-to-date research results in this important area of mathematics. Designs and Finite Geometries serves as an excellent reference, providing insight into some of the most important research issues in the field.

Group representations

CERN Document Server

Karpilovsky, G

1994-01-01

This third volume can be roughly divided into two parts. The first part is devoted to the investigation of various properties of projective characters. Special attention is drawn to spin representations and their character tables and to various correspondences for projective characters. Among other topics, projective Schur index and projective representations of abelian groups are covered. The last topic is investigated by introducing a symplectic geometry on finite abelian groups. The second part is devoted to Clifford theory for graded algebras and its application to the corresponding theory

Delocalized SYZ mirrors and confronting top-down SU(3)-structure holographic meson masses at finite g and N_c with P(article) D(ata) G(roup) values

Science.gov (United States)

Yadav, Vikas; Misra, Aalok; Sil, Karunava

2017-10-01

Meson spectroscopy at finite gauge coupling - whereat any perturbative QCD computation would break down - and finite number of colors, from a top-down holographic string model, has thus far been entirely missing in the literature. This paper fills this gap. Using the delocalized type IIA SYZ mirror (with SU(3) structure) of the holographic type IIB dual of large- N thermal QCD of Mia et al. (Nucl Phys B 839:187. arXiv:0902.1540 [hep-th], 2010) as constructed in Dhuria and Misra (JHEP 1311:001. arXiv:1306.4339 [hep-th], 2013) at finite coupling and number of colors (N_c = number of D5(\\overline{D5})-branes wrapping a vanishing two-cycle in the top-down holographic construct of Mia et al. (Nucl Phys B 839:187. arXiv:0902.1540 [hep-th], 2010) = O(1) in the IR in the MQGP limit of Dhuria and Misra (JHEP 1311:001. arXiv:1306.4339 [hep-th], 2013) at the end of a Seiberg-duality cascade), we obtain analytical (not just numerical) expressions for the vector and scalar meson spectra and compare our results with previous calculations of Sakai and Sugimoto (Prog Theor Phys 113:843. doi: 10.1143/PTP.113.843 arXiv:hep-th/0412141, 2005) and Dasgupta et al. (JHEP 1507:122. doi: 10.1007/JHEP07(2015)122 arXiv:1409.0559 [hep-th], 2015), and we obtain a closer match with the Particle Data Group (PDG) results of Olive et al. (Particle Data Group) (Chin Phys C 38:090001, 2014). Through explicit computations, we verify that the vector and scalar meson spectra obtained by the gravity dual with a black hole for all temperatures (small and large) are nearly isospectral with the spectra obtained by a thermal gravity dual valid for only low temperatures; the isospectrality is much closer for vector mesons than scalar mesons. The black-hole gravity dual (with a horizon radius smaller than the deconfinement scale) also provides the expected large- N suppressed decrease in vector meson mass with increase of temperature.

A hybrid finite-volume and finite difference scheme for depth-integrated non-hydrostatic model

Science.gov (United States)

Yin, Jing; Sun, Jia-wen; Wang, Xing-gang; Yu, Yong-hai; Sun, Zhao-chen

2017-06-01

A depth-integrated, non-hydrostatic model with hybrid finite difference and finite volume numerical algorithm is proposed in this paper. By utilizing a fraction step method, the governing equations are decomposed into hydrostatic and non-hydrostatic parts. The first part is solved by using the finite volume conservative discretization method, whilst the latter is considered by solving discretized Poisson-type equations with the finite difference method. The second-order accuracy, both in time and space, of the finite volume scheme is achieved by using an explicit predictor-correction step and linear construction of variable state in cells. The fluxes across the cell faces are computed in a Godunov-based manner by using MUSTA scheme. Slope and flux limiting technique is used to equip the algorithm with total variation dimensioning property for shock capturing purpose. Wave breaking is treated as a shock by switching off the non-hydrostatic pressure in the steep wave front locally. The model deals with moving wet/dry front in a simple way. Numerical experiments are conducted to verify the proposed model.

Entanglement entropy in quantum spin chains with broken reflection symmetry

International Nuclear Information System (INIS)

Kadar, Zoltan; Zimboras, Zoltan

2010-01-01

We investigate the entanglement entropy of a block of L sites in quasifree translation-invariant spin chains concentrating on the effect of reflection-symmetry breaking. The Majorana two-point functions corresponding to the Jordan-Wigner transformed fermionic modes are determined in the most general case; from these, it follows that reflection symmetry in the ground state can only be broken if the model is quantum critical. The large L asymptotics of the entropy are calculated analytically for general gauge-invariant models, which have, until now, been done only for the reflection-symmetric sector. Analytical results are also derived for certain nongauge-invariant models (e.g., for the Ising model with Dzyaloshinskii-Moriya interaction). We also study numerically finite chains of length N with a nonreflection-symmetric Hamiltonian and report that the reflection symmetry of the entropy of the first L spins is violated but the reflection-symmetric Calabrese-Cardy formula is recovered asymptotically. Furthermore, for noncritical reflection-symmetry-breaking Hamiltonians, we find an anomaly in the behavior of the saturation entropy as we approach the critical line. The paper also provides a concise but extensive review of the block-entropy asymptotics in translation-invariant quasifree spin chains with an analysis of the nearest-neighbor case and the enumeration of the yet unsolved parts of the quasifree landscape.

Broadband reflected wavefronts manipulation using structured phase gradient metasurfaces

Directory of Open Access Journals (Sweden)

Xiao-Peng Wang

2016-06-01

Full Text Available Acoustic metasurface (AMS is a good candidate to manipulate acoustic waves due to special acoustic performs that cannot be realized by traditional materials. In this paper, we design the AMS by using circular-holed cubic arrays. The advantages of our AMS are easy assemble, subwavelength thickness, and low energy loss for manipulating acoustic waves. According to the generalized Snell’s law, acoustic waves can be manipulated arbitrarily by using AMS with different phase gradients. By selecting suitable hole diameter of circular-holed cube (CHC, some interesting phenomena are demonstrated by our simulations based on finite element method, such as the conversion of incoming waves into surface waves, anomalous reflections (including negative reflection, acoustic focusing lens, and acoustic carpet cloak. Our results can provide a simple approach to design AMSes and use them in wavefront manipulation and manufacturing of acoustic devices.

Graphs of groups on surfaces interactions and models

CERN Document Server

White, AT

2001-01-01

The book, suitable as both an introductory reference and as a text book in the rapidly growing field of topological graph theory, models both maps (as in map-coloring problems) and groups by means of graph imbeddings on sufaces. Automorphism groups of both graphs and maps are studied. In addition connections are made to other areas of mathematics, such as hypergraphs, block designs, finite geometries, and finite fields. There are chapters on the emerging subfields of enumerative topological graph theory and random topological graph theory, as well as a chapter on the composition of English

Ultrafilters and topologies on groups

CERN Document Server

Zelenyuk, Yevhen

2011-01-01

This book presents the relationship between ultrafilters and topologies on groups. It shows how ultrafilters are used in constructing topologies on groups with extremal properties and how topologies on groups serve in deriving algebraic results aboutultrafilters. Topics covered include: topological and left topological groups, ultrafilter semigroups, local homomorphisms and automorphisms, subgroups and ideal structure of ßG, almost maximal spaces and projectives of finite semigroups, resolvability of groups. This is a self-contained book aimed at graduate students and researchers working in to

A study of the consistent and the lumped source approximations in finite element neutron diffusion calculations

International Nuclear Information System (INIS)

Ozgener, B.; Azgener, H.A.

1991-01-01

In finite element formulations for the solution of the within-group neutron diffusion equation, two different treatments are possible for the group source term: the consistent source approximation (CSA) and the lumped source approximation (LSA). CSA results in intra-group scattering and fission matrices which have the same nondiagonal structure as the global coefficient matrix. This situation might be regarded as a disadvantage, compared to the conventional (i.e. finite difference) methods where the intra-group scattering and fission matrices are diagonal. To overcome this disadvantage, LSA could be used to diagonalize these matrices. LSA is akin to the lumped mass approximation of continuum mechanics. We concentrate on two different aspects of the source approximations. Although it has been reported that LSA does not modify the asymptotic h 2 convergence behaviour for linear elements, the effect of LSA on convergence of higher degree elements has not been investigated. Thus, we would be interested in determining, p, the asymptotic order of convergence, in: Δk |k eff (analytical) -k eff (finite element)| = Ch p (1) for finite element approximations of varying degree (N) with both of the source approximations. Since (1) is valid in the asymptotic limit, we must use ultra-fine meshes and quadruple precision arithmetic. For our order of convergence study, we used infinite cylindrical geometry with azimuthal symmetry. Hence, the effects of singularities remain uninvestigated. The second aspect we dwell on is the performance of LSA in bilinear 3-D finite element calculations, compared to CSA. LSA has been used quite extensively in 1- and 2-D even-parity transport and diffusion calculations. In this work, we will try to assess the relative merits of LSA and CSA in 3-D problems. (author)

Convergence analysis of the rebalance methods in multiplying finite slab having periodic boundary conditions

International Nuclear Information System (INIS)

Hong, Ser Gi; Lee, Young Ouk; Song, Jae Seung

2009-01-01

This paper analyzes the convergence of the rebalance iteration methods for the discrete ordinates transport equation in the multiplying finite slab problem. The finite slab is assumed to be homogeneous and it has the periodic boundary conditions. A general formulation is used to include three well-known rebalance methods of the linearized form in a unified way. The rebalance iteration methods considered in this paper are the CMR (Coarse-Mesh Rebalance), the CMFD (Coarse-Mesh Finite Difference), and p-CMFD (Partial Current-Based Coarse Mesh Finite Difference) methods which have been popularly used in the reactor physics. The convergence analysis is performed with the well-known Fourier analysis through a linearization. The analyses are applied for one-group problems. The theoretical analysis shows that there are one fundamental mode and N-1 Eigen-modes which determine the convergence if the finite slab is divided into N uniform meshes. The numerical tests show that the Fourier convergence analysis provides the reasonable estimate of the numerical spectral radii for the model problems and the spectral radius for the finite slab approaches the one for the infinite slab as the thickness of the slab increases. (author)

Reflections on Conformal Spectra

CERN Multimedia

CERN. Geneva

2015-01-01

We use modular invariance and crossing symmetry of conformal field theory to reveal approximate reflection symmetries in the spectral decompositions of the partition function in two dimensions in the limit of large central charge and of the four-point function in any dimension in the limit of large scaling dimensions Δ0 of external operators. We use these symmetries to motivate universal upper bounds on the spectrum and the operator product expansion coefficients, which we then derive by independent techniques. Some of the bounds for four-point functions are valid for finite Δ0 as well as for large Δ0. We discuss a similar symmetry in a large spacetime dimension limit. Finally, we comment on the analogue of the Cardy formula and sparse light spectrum condition for the four-point function. (based on 1510.08772 with Kim & Ooguri). This seminar will be given via videolink

Relativistic finite-temperature Thomas-Fermi model

Science.gov (United States)

Faussurier, Gérald

2017-11-01

We investigate the relativistic finite-temperature Thomas-Fermi model, which has been proposed recently in an astrophysical context. Assuming a constant distribution of protons inside the nucleus of finite size avoids severe divergence of the electron density with respect to a point-like nucleus. A formula for the nuclear radius is chosen to treat any element. The relativistic finite-temperature Thomas-Fermi model matches the two asymptotic regimes, i.e., the non-relativistic and the ultra-relativistic finite-temperature Thomas-Fermi models. The equation of state is considered in detail. For each version of the finite-temperature Thomas-Fermi model, the pressure, the kinetic energy, and the entropy are calculated. The internal energy and free energy are also considered. The thermodynamic consistency of the three models is considered by working from the free energy. The virial question is also studied in the three cases as well as the relationship with the density functional theory. The relativistic finite-temperature Thomas-Fermi model is far more involved than the non-relativistic and ultra-relativistic finite-temperature Thomas-Fermi models that are very close to each other from a mathematical point of view.

Use of the Fox derivatives in the solution of the word problem for groups

International Nuclear Information System (INIS)

Majumdar, S.

1988-09-01

Applying Fox's free partial derivative, the word problem of a finitely presented group has been reduced to the problem of finding an algorithm for determining the existence of a root of a system of linear equations over the integral group ring. The solubility of the word problem for torsion-free one-relator groups and torsion-free polycyclic-by-finite groups has been deduced. (author). 10 refs

Guessing lexicon entries using finite-state methods

OpenAIRE

Koskenniemi, Kimmo Matti

2018-01-01

A practical method for interactive guessing of LEXC lexicon entries is presented. The method is based on describing groups of similarly inflected words using regular expressions. The patterns are compiled into a finite-state transducer (FST) which maps any word form into the possible LEXC lexicon entries which could generate it. The same FST can be used (1) for converting conventional headword lists into LEXC entries, (2) for interactive guessing of entries, (3) for corpus-assisted interactiv...

Requirements for reflection in the critical care environment

Directory of Open Access Journals (Sweden)

Celia J. Filmalter

2015-03-01

Full Text Available Background: Reflection is recognised as an important method for practice development. The importance of reflection is well documented in the literature, but the requirements for reflection remain unclear. Objectives: To explore and describe the requirements for reflection in the critical care environment as viewed by educators of qualified critical care nurses. Method: A focus group interview was conducted to explore and describe the views of educators of qualified critical care nurses regarding requirements for reflection in the critical care environment. Results: The themes that emerged from the focus group were buy-in from stakeholders –management, facilitators and critical care nurses, and the need to create an environment where reflection can occur. Conclusion: Critical care nurses should be allowed time to reflect on their practice and be supported by peers as well as a facilitator in a non-intimidating way to promote emancipatorypractice development.

Supersymmetric theories and finiteness

International Nuclear Information System (INIS)

Helayel-Neto, J.A.

1989-01-01

We attempt here to present a short survey of the all-order finite Lagrangian field theories known at present in four-and two-dimensional space-times. The question of the possible relevance of these ultraviolet finite models in the formulation of consistent unified frameworks for the fundamental forces is also addressed to. (author)

A first course in finite elements

CERN Document Server

Fish, Jacob

2007-01-01

Developed from the authors, combined total of 50 years undergraduate and graduate teaching experience, this book presents the finite element method formulated as a general-purpose numerical procedure for solving engineering problems governed by partial differential equations.  Focusing on the formulation and application of the finite element method through the integration of finite element theory, code development, and software application, the book is both introductory and self-contained, as well as being a hands-on experience for any student. This authoritative text on Finite Elements:Adopts

Features of finite quantum field theories

International Nuclear Information System (INIS)

Boehm, M.; Denner, A.

1987-01-01

We analyse general features of finite quantum field theories. A quantum field theory is considered to be finite, if the corresponding renormalization constants evaluated in the dimensional regularization scheme are free from divergences in all orders of perturbation theory. We conclude that every finite renormalizable quantum field theory with fields of spin one or less must contain both scalar fields and fermion fields and nonabelian gauge fields. Some secific nonsupersymmetric models are found to be finite at the one- and two-loop level. (orig.)

Unipotent and nilpotent classes in simple algebraic groups and lie algebras

CERN Document Server

Liebeck, Martin W

2012-01-01

This book concerns the theory of unipotent elements in simple algebraic groups over algebraically closed or finite fields, and nilpotent elements in the corresponding simple Lie algebras. These topics have been an important area of study for decades, with applications to representation theory, character theory, the subgroup structure of algebraic groups and finite groups, and the classification of the finite simple groups. The main focus is on obtaining full information on class representatives and centralizers of unipotent and nilpotent elements. Although there is a substantial literature on this topic, this book is the first single source where such information is presented completely in all characteristics. In addition, many of the results are new--for example, those concerning centralizers of nilpotent elements in small characteristics. Indeed, the whole approach, while using some ideas from the literature, is novel, and yields many new general and specific facts concerning the structure and embeddings of...

Reflection-Based Learning for Professional Ethical Formation.

Science.gov (United States)

Branch, William T; George, Maura

2017-04-01

One way practitioners learn ethics is by reflecting on experience. They may reflect in the moment (reflection-in-action) or afterwards (reflection-on-action). We illustrate how a teaching clinician may transform relationships with patients and teach person-centered care through reflective learning. We discuss reflective learning pedagogies and present two case examples of our preferred method, guided group reflection using narratives. This method fosters moral development alongside professional identity formation in students and advanced learners. Our method for reflective learning addresses and enables processing of the most pressing ethical issues that learners encounter in practice. © 2017 American Medical Association. All Rights Reserved.

FDTD analysis of reflection of electromagnetic wave from a conductive plane covered with inhomogeneous time-varying plasma

International Nuclear Information System (INIS)

Liu Shaobin; Mo Jinjun; Yuan Naichang

2003-01-01

A finite-difference time-domain (FDTD) algorithm is applied to study the electro-magnetic reflection of conduction plane covered with inhomogeneous time-varying plasma, homogeneous plasma and inhomogeneous plasma. The collisions frequency of plasma is a function of electron density and plasma temperature. The number density profile follows a parabolic function. A discussion on the effect of various plasma parameters on the reflection coefficient is presented. Under the one-dimensional case, transient electromagnetic propagation through various plasmas has been obtained, and the reflection coefficients of EM wave through various plasma are calculated under different conditions. The results illustrate that a plasma cloaking system can successfully absorb the incident EM wave

The forced sound transmission of finite single leaf walls using a variational technique.

Science.gov (United States)

Brunskog, Jonas

2012-09-01

The single wall is the simplest element of concern in building acoustics, but there still remain some open questions regarding the sound insulation of this simple case. The two main reasons for this are the effects on the excitation and sound radiation of the wall when it has a finite size, and the fact that the wave field in the wall is consisting of two types of waves, namely forced waves due to the exciting acoustic field, and free bending waves due to reflections in the boundary. The aim of the present paper is to derive simple analytical formulas for the forced part of the airborne sound insulation of a single homogeneous wall of finite size, using a variational technique based on the integral-differential equation of the fluid loaded wall. The so derived formulas are valid in the entire audible frequency range. The results are compared with full numerical calculations, measurements and alternative theory, with reasonable agreement.

The forced sound transmission of finite single leaf walls using a variational technique

DEFF Research Database (Denmark)

Brunskog, Jonas

2012-01-01

The single wall is the simplest element of concern in building acoustics, but there still remain some open questions regarding the sound insulation of this simple case. The two main reasons for this are the effects on the excitation and sound radiation of the wall when it has a finite size......, and the fact that the wave field in the wall is consisting of two types of waves, namely forced waves due to the exciting acoustic field, and free bending waves due to reflections in the boundary. The aim of the present paper is to derive simple analytical formulas for the forced part of the airborne sound...... insulation of a single homogeneous wall of finite size, using a variational technique based on the integral-differential equation of the fluid loaded wall. The so derived formulas are valid in the entire audible frequency range. The results are compared with full numerical calculations, measurements...

Optical phase conjugation for time-domain undoing of dispersive self-phase-modulation effects

International Nuclear Information System (INIS)

Fisher, R.A.; Suydam, B.R.; Yevick, D.

1983-01-01

We show that the temporal distortion and spectral broadening of a pulse generated by the combined effects of group-velocity dispersion and self-phase modulation is removed by reflection of a cw-pumped, broadband, unity-reflecting Kerr-like optical phase conjugator followed by retraversal of the nonlinear medium. We also examine numerically the effects of finite linear loss in the material, of nonunity conjugate reflectivity, and of finite conjugator thickness

Strong interaction at finite temperature

Indian Academy of Sciences (India)

Quantum chromodynamics; finite temperature; chiral perturbation theory; QCD sum rules. PACS Nos 11.10. ..... at finite temperature. The self-energy diagrams of figure 2 modify it to ..... method of determination at present. Acknowledgement.

Sixth Graders' Co-Construction of Explanations of a Disturbance in an Ecosystem: Exploring Relationships between Grouping, Reflective Scaffolding, and Evidence-Based Explanations

Science.gov (United States)

Kyza, Eleni A.; Constantinou, Costas P.; Spanoudis, George

2011-01-01

We report on a study investigating the relationship between cognitive ability grouping, reflective inquiry scaffolding, and students' collaborative explanations of an ecosystem disturbance which took place when a number of flamingo birds died in a salt lake because of nearby intensive human activities. Twenty-six pairs of students from two intact…

The weight hierarchies and chain condition of a class of codes from varieties over finite fields

Science.gov (United States)

Wu, Xinen; Feng, Gui-Liang; Rao, T. R. N.

1996-01-01

The generalized Hamming weights of linear codes were first introduced by Wei. These are fundamental parameters related to the minimal overlap structures of the subcodes and very useful in several fields. It was found that the chain condition of a linear code is convenient in studying the generalized Hamming weights of the product codes. In this paper we consider a class of codes defined over some varieties in projective spaces over finite fields, whose generalized Hamming weights can be determined by studying the orbits of subspaces of the projective spaces under the actions of classical groups over finite fields, i.e., the symplectic groups, the unitary groups and orthogonal groups. We give the weight hierarchies and generalized weight spectra of the codes from Hermitian varieties and prove that the codes satisfy the chain condition.

Reflective writing: the student nurse's perspective on reflective writing and poetry writing.

Science.gov (United States)

Coleman, Dawn; Willis, Diane S

2015-07-01

Reflective writing is a mandatory part of nurse education but how students develop their skills and use reflection as part of their experiential learning remains relatively unknown. Understanding reflective writing in all forms from the perspective of a student nurse is therefore important. To explore the use of reflective writing and the use of poetry in pre-registered nursing students. A qualitative design was employed to explore reflective writing in pre-registered nursing students. A small university in Scotland. BSc (Hons) Adult and Mental Health Pre-registration Student Nurses. Two focus groups were conducted with 10 student nurses during March 2012. Data was analysed thematically using the framework of McCarthy (1999). Students found the process of reflective writing daunting but valued it over time. Current educational methods, such as assessing reflective accounts, often lead to the 'narrative' being watered down and the student feeling judged. Despite this, reflection made students feel responsible for their own learning and research on the topic. Some students felt the use of models of reflection constricting, whilst poetry freed up their expression allowing them to demonstrate the compassion for their patient under their care. Poetry writing gives students the opportunity for freedom of expression, personal satisfaction and a closer connection with their patients, which the more formal approach to reflective writing did not offer. There is a need for students to have a safe and supportive forum in which to express and have their experiences acknowledged without the fear of being judged. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Introduction to quantum groups

International Nuclear Information System (INIS)

Monteiro, Marco A.R.

1994-01-01

An elementary introduction to quantum groups is presented. The example of Universal Enveloping Algebra of deformed SU(2) is analysed in detail. It is also discussed systems made up of bosonic q-oscillators at finite temperature within the formalism of Thermo-Field Dynamics. (author). 39 refs

Group C∗-algebras without the completely bounded approximation property

DEFF Research Database (Denmark)

Haagerup, U.

2016-01-01

It is proved that: (1) The Fourier algebra A(G) of a simple Lie group G of real rank at least 2 with finite center does not have a multiplier bounded approximate unit. (2) The reduced C∗-algebra C∗ r of any lattice in a non-compact simple Lie group of real rank at least 2 with finite center does...... not have the completely bounded approximation property. Hence, the results obtained by de Canniere and the author for SOe (n, 1), n ≥ 2, and by Cowling for SU(n, 1) do not generalize to simple Lie groups of real rank at least 2. © 2016 Heldermann Verlag....

Symmetry an introduction to group theory and its applications

CERN Document Server

McWeeny, Roy

2002-01-01

Well-organized volume develops ideas of group and representation theory in progressive fashion. Emphasis on finite groups describing symmetry of regular polyhedra and of repeating patterns, plus geometric illustrations.

Counting Semisimple Orbits of Finite Lie Algebras by Genus

OpenAIRE

Fulman, Jason

1999-01-01

The adjoint action of a finite group of Lie type on its Lie algebra is studied. A simple formula is conjectured for the number of split semisimple orbits of a given genus. This conjecture is proved for type A, and partial results are obtained for other types. For type A a probabilistic interpretation is given in terms of card shuffling.

Finiteness of quantum field theories and supersymmetry

International Nuclear Information System (INIS)

Lucha, W.; Neufeld, H.

1986-01-01

We study the consequences of finiteness for a general renormalizable quantum field theory by analysing the finiteness conditions resulting from the requirement of absence of divergent contributions to the renormalizations of the parameters of an arbitrary gauge theory. In all cases considered, the well-known two-loop finite supersymmetric theories prove to be the unique solution of the finiteness criterion. (Author)

On the Brauer group

International Nuclear Information System (INIS)

Tankeev, Sergei G

2000-01-01

For an arithmetic model X of a Fermat surface or a hyperkahler variety with Betti number b 2 (V otimes k-bar)>3 over a purely imaginary number field k, we prove the finiteness of the l-components of Br'(X) for all primes l>>0. This yields a variant of a conjecture of M. Artin. If V is a smooth projective irregular surface over a number field k and V(k)≠ nothing, then the l-primary component of Br(V)/Br(k) is an infinite group for every prime l. Let A 1 →M 1 be the universal family of elliptic curves with a Jacobian structure of level N>=3 over a number field k supset of Q(e 2πi/N ). Assume that M 1 (k) ≠ nothing. If V is a smooth projective compactification of the surface A 1 , then the l-primary component of Br(V)/Br(M-bar 1 ) is a finite group for each sufficiently large prime l

Automatic Construction of Finite Algebras

Institute of Scientific and Technical Information of China (English)

张健

1995-01-01

This paper deals with model generation for equational theories,i.e.,automatically generating (finite)models of a given set of (logical) equations.Our method of finite model generation and a tool for automatic construction of finite algebras is described.Some examples are given to show the applications of our program.We argue that,the combination of model generators and theorem provers enables us to get a better understanding of logical theories.A brief comparison betwween our tool and other similar tools is also presented.

Finite groups in which some particular subgroups are TI-subgroups

DEFF Research Database (Denmark)

Shi, Jiangtao; Zhang, Cui

2013-01-01

We prove that G is a group in which all noncyclic subgroups are TI-subgroups if and only if all noncyclic subgroups of G are normal in G. Moreover, we classify groups in which all subgroups of even order are TI-subgroups....

Simulation on Temperature Field of Radiofrequency Lesions System Based on Finite Element Method

International Nuclear Information System (INIS)

Xiao, D; Qian, Z; Li, W; Qian, L

2011-01-01

This paper mainly describes the way to get the volume model of damaged region according to the simulation on temperature field of radiofrequency ablation lesion system in curing Parkinson's disease based on finite element method. This volume model reflects, to some degree, the shape and size of the damaged tissue during the treatment with all tendencies in different time or core temperature. By using Pennes equation as heat conduction equation of radiofrequency ablation of biological tissue, the author obtains the temperature distribution field of biological tissue in the method of finite element for solving equations. In order to establish damage models at temperature points of 60 deg. C, 65 deg. C, 70 deg. C, 75 deg. C, 80 deg. C, 85 deg. C and 90 deg. C while the time points are 30s, 60s, 90s and 120s, Parkinson's disease model of nuclei is reduced to uniform, infinite model with RF pin at the origin. Theoretical simulations of these models are displayed, focusing on a variety of conditions about the effective lesion size on horizontal and vertical. The results show the binary complete quadratic non-linear joint temperature-time models of the maximum damage diameter and maximum height. The models can comprehensively reflect the degeneration of target tissue caused by radio frequency temperature and duration. This lay the foundation for accurately monitor of clinical RF treatment of Parkinson's disease in the future.

A Posteriori Error Estimation for Finite Element Methods and Iterative Linear Solvers

Energy Technology Data Exchange (ETDEWEB)

Melboe, Hallgeir

2001-10-01

This thesis addresses a posteriori error estimation for finite element methods and iterative linear solvers. Adaptive finite element methods have gained a lot of popularity over the last decades due to their ability to produce accurate results with limited computer power. In these methods a posteriori error estimates play an essential role. Not only do they give information about how large the total error is, they also indicate which parts of the computational domain should be given a more sophisticated treatment in order to reduce the error. A posteriori error estimates are traditionally aimed at estimating the global error, but more recently so called goal oriented error estimators have been shown a lot of interest. The name reflects the fact that they estimate the error in user-defined local quantities. In this thesis the main focus is on global error estimators for highly stretched grids and goal oriented error estimators for flow problems on regular grids. Numerical methods for partial differential equations, such as finite element methods and other similar techniques, typically result in a linear system of equations that needs to be solved. Usually such systems are solved using some iterative procedure which due to a finite number of iterations introduces an additional error. Most such algorithms apply the residual in the stopping criterion, whereas the control of the actual error may be rather poor. A secondary focus in this thesis is on estimating the errors that are introduced during this last part of the solution procedure. The thesis contains new theoretical results regarding the behaviour of some well known, and a few new, a posteriori error estimators for finite element methods on anisotropic grids. Further, a goal oriented strategy for the computation of forces in flow problems is devised and investigated. Finally, an approach for estimating the actual errors associated with the iterative solution of linear systems of equations is suggested. (author)

Nilpotent groups related to an automorphism 1 Introduction

Indian Academy of Sciences (India)

29

The extension of a nilpotent group has been studied by different authors. .... study absolute normal subgroups of some finite groups. ...... follows from the relations ... To prove H3 is absolute normal we should investigate four following cases.

Temperature renormalization group approach to spontaneous symmetry breaking

International Nuclear Information System (INIS)

Manesis, E.; Sakakibara, S.

1985-01-01

We apply renormalization group equations that describe the finite-temperature behavior of Green's functions to investigate thermal properties of spontaneous symmetry breaking. Specifically, in the O(N).O(N) symmetric model we study the change of symmetry breaking patterns with temperature, and show that there always exists the unbroken symmetry phase at high temperature, modifying the naive result of leading order in finite-temperature perturbation theory. (orig.)

Generalized finite elements

International Nuclear Information System (INIS)

Wachspress, E.

2009-01-01

Triangles and rectangles are the ubiquitous elements in finite element studies. Only these elements admit polynomial basis functions. Rational functions provide a basis for elements having any number of straight and curved sides. Numerical complexities initially associated with rational bases precluded extensive use. Recent analysis has reduced these difficulties and programs have been written to illustrate effectiveness. Although incorporation in major finite element software requires considerable effort, there are advantages in some applications which warrant implementation. An outline of the basic theory and of recent innovations is presented here. (authors)

Characterization of resonances using finite size effects

International Nuclear Information System (INIS)

Pozsgay, B.; Takacs, G.

2006-01-01

We develop methods to extract resonance widths from finite volume spectra of (1+1)-dimensional quantum field theories. Our two methods are based on Luscher's description of finite size corrections, and are dubbed the Breit-Wigner and the improved ''mini-Hamiltonian'' method, respectively. We establish a consistent framework for the finite volume description of sufficiently narrow resonances that takes into account the finite size corrections and mass shifts properly. Using predictions from form factor perturbation theory, we test the two methods against finite size data from truncated conformal space approach, and find excellent agreement which confirms both the theoretical framework and the numerical validity of the methods. Although our investigation is carried out in 1+1 dimensions, the extension to physical 3+1 space-time dimensions appears straightforward, given sufficiently accurate finite volume spectra

Real Elements and p-Nilpotence of Finite Groups

Directory of Open Access Journals (Sweden)

Adolfo Ballester-Bolinches

2016-12-01

Full Text Available Our first main result proves that every element of order 4 of a Sylow 2-subgroup S of a minimal non-2-nilpotent group G, is a real element of S. This allows to give a character-free proof of a theorem due to Isaacs and Navarro (see [9, Theorem B]. As an application, the authors show a common extension of the p-nilpotence criteria proved in [3] and [9].

Heat transfer within a concrete slab with a finite microwave heating source

International Nuclear Information System (INIS)

Lagos, L.E.; Li, W.; Ebadian, M.A.; Grubb, R.G.

1995-01-01

In the present paper, the concrete decontamination and decommissioning process with a finite microwave heating source is investigated theoretically. For the microwave induced heating pattern, a multilayer concrete slab, which includes steel reinforcement mesh, is assumed to be exposed to a finite plane microwave source at normal incidence. Two-dimensional heat transport within the concrete is also considered to evaluate the variations of temperature with heating time at different frequencies with and without the presence of the reinforcement bars. Four commonly used industrial microwave frequencies of 0.896, 2.45, 10.6 and 18.0 GHz have been selected. The results revealed that as the microwave frequency increases to, or higher than 10.6 GHz, the maximum temperature shifts toward the front surface of the concrete. It was found that the presence of a steel reinforcement mesh causes part of the microwave energy to be blocked and reflected. Furthermore, it was observed that the temperature distribution is nearly uniform within the dimensions of the microwave applicator for a high microwave power intensity and a short heating time. (author)

Permutation representations of the orbits of the automorphism group ...

Indian Academy of Sciences (India)

Abstract. Consider a discrete valuation ring R whose residue field is finite of car- dinality at least 3. For a finite torsion module, we consider transitive subsets O under the action of the automorphism group of the module. We prove that the associated per- mutation representation on the complex vector space C[O] is multiplicity ...

Finite difference solution of the time dependent neutron group diffusion equations

International Nuclear Information System (INIS)

Hendricks, J.S.; Henry, A.F.

1975-08-01

In this thesis two unrelated topics of reactor physics are examined: the prompt jump approximation and alternating direction checkerboard methods. In the prompt jump approximation it is assumed that the prompt and delayed neutrons in a nuclear reactor may be described mathematically as being instantaneously in equilibrium with each other. This approximation is applied to the spatially dependent neutron diffusion theory reactor kinetics model. Alternating direction checkerboard methods are a family of finite difference alternating direction methods which may be used to solve the multigroup, multidimension, time-dependent neutron diffusion equations. The reactor mesh grid is not swept line by line or point by point as in implicit or explicit alternating direction methods; instead, the reactor mesh grid may be thought of as a checkerboard in which all the ''red squares'' and '' black squares'' are treated successively. Two members of this family of methods, the ADC and NSADC methods, are at least as good as other alternating direction methods. It has been found that the accuracy of implicit and explicit alternating direction methods can be greatly improved by the application of an exponential transformation. This transformation is incompatible with checkerboard methods. Therefore, a new formulation of the exponential transformation has been developed which is compatible with checkerboard methods and at least as good as the former transformation for other alternating direction methods

Structural modeling techniques by finite element method

International Nuclear Information System (INIS)

Kang, Yeong Jin; Kim, Geung Hwan; Ju, Gwan Jeong

1991-01-01

This book includes introduction table of contents chapter 1 finite element idealization introduction summary of the finite element method equilibrium and compatibility in the finite element solution degrees of freedom symmetry and anti symmetry modeling guidelines local analysis example references chapter 2 static analysis structural geometry finite element models analysis procedure modeling guidelines references chapter 3 dynamic analysis models for dynamic analysis dynamic analysis procedures modeling guidelines and modeling guidelines.

Journaling: a quasi-experimental study of student nurses' reflective learning ability.

Science.gov (United States)

Fakude, L P; Bruce, J C

2003-08-01

The use of journaling or journal writing in clinical education is one of the strategies used to develop critical thinking. Reflective journal writing, as it is commonly known, can nurture many qualities of a critical thinker and promote thoughtful nursing practice. Using a quasi-experimental design in this study, reflective journaling was introduced to a sample of first year Bridging Course student nurses at a Private Nursing Education Institution, to assess its effectiveness in reflective learning. The study design enabled comparisons between two groups: one group of students assigned to do journaling (experimental group) and another group of students (control group) who did not journal. The students in the experimental group were given a period of eight weeks to journal their clinical experiences. At the end of this period, both groups were given an exercise, based on a clinical situation, to analyse reflectively and a comparison made on their performance. Descriptive statistics were used to analyse data and Fisher's Exact Test was used to determine the significance of differences observed within and between groups. The results showed that students in the experimental group performed better in exploring alternatives of action (p < 0.10) and formulating responses in similar future situations (p < 0.05) during the process of reflection. There was no significant difference between the groups' scores with regard to their ability to describe the clinical experience, to explore their related feelings, to evaluate the experience and to interpret/create meaning for themselves. Recommendations are made for continued student support and guidance during clinical education if reflection is considered to enhance reflective, thoughtful nursing practice.

Finite Element Method Analysis of An Out Flow With Free Surface In Transition Zones

Science.gov (United States)

Saoula, R. Iddir S.; Mokhtar, K. Ait

The object of this work is to present this part of the fluid mechanics that relates to out-flows of the fluid to big speeds in transitions. Results usually gotten by the classic processes can only have a qualitative aspect. The method fluently used for the count of these out-flows to big speeds is the one of characteristics, this approach remains interesting so much that doesn't appear within the out-flow of intersections of shock waves, as well as of reflections of these. In the simple geometry case, the method of finite differences satisfying result, But when the complexity of this geometry imposes itself, it is the method of finite elements that is proposed to solve this type of prob- lem, in particular for problems Trans critic. The goal of our work is to analyse free surface flows in channels no prismatic has oblong transverse section in zone of tran- sition. (Convergent, divergent). The basic mathematical model of this study is Saint Venant derivatives partial equations. To solve these equations we use the finite ele- ment method, the element of reference is the triangular element with 6 nodes which are quadratic in speed and linear in height (pressure). Our results and their obtains by others are very close to experimental results.

Reflections of a Latino Associate Professor

Science.gov (United States)

Peguero, Anthony A.

2018-01-01

The following reflection essay is about my experiences as a Latino Associate Professor who focuses on criminology, youth violence, juvenile justice, and the associated disparities with race, ethnicity, and immigration. I reflect about the "race and justice" job market, pursuing and establishing a Latina/o Criminology working group, often…

From a particle in a box to the uncertainty relation in a quantum dot and to reflecting walls for relativistic fermions

International Nuclear Information System (INIS)

Al-Hashimi, M.H.; Wiese, U.-J.

2012-01-01

We consider a 1-parameter family of self-adjoint extensions of the Hamiltonian for a particle confined to a finite interval with perfectly reflecting boundary conditions. In some cases, one obtains negative energy states which seem to violate the Heisenberg uncertainty relation. We use this as a motivation to derive a generalized uncertainty relation valid for an arbitrarily shaped quantum dot with general perfectly reflecting walls in d dimensions. In addition, a general uncertainty relation for non-Hermitian operators is derived and applied to the non-Hermitian momentum operator in a quantum dot. We also consider minimal uncertainty wave packets in this situation, and we prove that the spectrum depends monotonically on the self-adjoint extension parameter. In addition, we construct the most general boundary conditions for semiconductor heterostructures such as quantum dots, quantum wires, and quantum wells, which are characterized by a 4-parameter family of self-adjoint extensions. Finally, we consider perfectly reflecting boundary conditions for relativistic fermions confined to a finite volume or localized on a domain wall, which are characterized by a 1-parameter family of self-adjoint extensions in the (1+1)-d and (2+1)-d cases, and by a 4-parameter family in the (3+1)-d and (4+1)-d cases. - Highlights: ► Finite volume Heisenberg uncertainty relation. ► General self-adjoint extensions for relativistic fermions. ► New prospective for the problem of particle in a box.

Fermionic spectral functions in backreacting p-wave superconductors at finite temperature

Energy Technology Data Exchange (ETDEWEB)

Giordano, G.L.; Grandi, N.E.; Lugo, A.R. [Instituto de Física de La Plata - CONICET & Departamento de Física - UNLP,C.C. 67, 1900 La Plata (Argentina)

2017-04-14

We investigate the spectral function of fermions in a p-wave superconducting state, at finite both temperature and gravitational coupling, using the AdS/CFT correspondence and extending previous research. We found that, for any coupling below a critical value, the system behaves as its zero temperature limit. By increasing the coupling, the “peak-dip-hump” structure that characterizes the spectral function at fixed momenta disappears. In the region where the normal/superconductor phase transition is first order, the presence of a non-zero order parameter is reflected in the absence of rotational symmetry in the fermionic spectral function at the critical temperature.

Supersymmetry at finite temperature

International Nuclear Information System (INIS)

Clark, T.E.; Love, S.T.

1983-01-01

Finite-temperature supersymmetry (SUSY) is characterized by unbroken Ward identities for SUSY variations of ensemble averages of Klein-operator inserted imaginary time-ordered products of fields. Path-integral representations of these products are defined and the Feynman rules in superspace are given. The finite-temperature no-renormalization theorem is derived. Spontaneously broken SUSY at zero temperature is shown not to be restored at high temperature. (orig.)

An introduction to finite tight frames

CERN Document Server

Waldron, Shayne F D

2018-01-01

This textbook is an introduction to the theory and applications of finite tight frames, an area that has developed rapidly in the last decade. Stimulating much of this growth are the applications of finite frames to diverse fields such as signal processing, quantum information theory, multivariate orthogonal polynomials, and remote sensing. Key features and topics: * First book entirely devoted to finite frames * Extensive exercises and MATLAB examples for classroom use * Important examples, such as harmonic and Heisenberg frames, are presented in preliminary chapters, encouraging readers to explore and develop an intuitive feeling for tight frames * Later chapters delve into general theory details and recent research results * Many illustrations showing the special aspects of the geometry of finite frames * Provides an overview of the field of finite tight frames * Discusses future research directions in the field Featuring exercises and MATLAB examples in each chapter, the book is well suited as a textbook ...

Finite Verb Morphology in the Spontaneous Speech of Dutch-Speaking Children With Hearing Loss.

Science.gov (United States)

Hammer, Annemiek; Coene, Martine

2016-01-01

In this study, the acquisition of Dutch finite verb morphology is investigated in children with cochlear implants (CIs) with profound hearing loss and in children with hearing aids (HAs) with moderate to severe hearing loss. Comparing these two groups of children increases our insight into how hearing experience and audibility affect the acquisition of morphosyntax. Spontaneous speech samples were analyzed of 48 children with CIs and 29 children with HAs, ages 4 to 7 years. These language samples were analyzed by means of standardized language analysis involving mean length of utterance, the number of finite verbs produced, and target-like subject-verb agreement. The outcomes were interpreted relative to expectations based on the performance of typically developing peers with normal hearing. Outcomes of all measures were correlated with hearing level in the group of HA users and age at implantation in the group of CI users. For both groups, the number of finite verbs that were produced in 50-utterance sample was on par with mean length of utterance and at the lower bound of the normal distribution. No significant differences were found between children with CIs and HAs on any of the measures under investigation. Yet, both groups produced more subject-verb agreement errors than are to be expected for typically developing hearing peers. No significant correlation was found between the hearing level of the children and the relevant measures of verb morphology, both with respect to the overall number of verbs that were used and the number of errors that children made. Within the group of CI users, the outcomes were significantly correlated with age at implantation. When producing finite verb morphology, profoundly deaf children wearing CIs perform similarly to their peers with moderate-to-severe hearing loss wearing HAs. Hearing loss negatively affects the acquisition of subject-verb agreement regardless of the hearing device (CI or HA) that the child is wearing. The

Non-linear finite element modeling

DEFF Research Database (Denmark)

Mikkelsen, Lars Pilgaard

The note is written for courses in "Non-linear finite element method". The note has been used by the author teaching non-linear finite element modeling at Civil Engineering at Aalborg University, Computational Mechanics at Aalborg University Esbjerg, Structural Engineering at the University...

Quantum statistical metastability for a finite spin

Science.gov (United States)

Garanin, D. A.; Chudnovsky, E. M.

2001-01-01

We study quantum-classical escape-rate transitions for uniaxial and biaxial models with finite spins S=10 (such as Mn12Ac and Fe8) and S=100 by a direct numerical approach. At second-order transitions the level making a dominant contribution into thermally assisted tunneling changes gradually with temperature whereas at first-order transitions a group of levels is skipped. For finite spins, the quasiclassical boundaries between first- and second-order transitions are shifted, favoring a second-order transition: For Fe8 in zero field the transition should be first order according to a theory with S-->∞, but we show that there are no skipped levels at the transition. Applying a field along the hard axis in Fe8 makes transition the strongest first order. For the same model with S=100 we confirmed the existence of a region where a second-order transition is followed by a first-order transition [X. Martínes Hidalgo and E. M. Chudnovsky, J. Phys.: Condensed Matter 12, 4243 (2000)].

Unitarizability, Maurey-Nikishin factorization, and Polish groups of finite type

DEFF Research Database (Denmark)

Ando, Hiroshi; Matsuzawa, Yasumichi; Thom, Andreas

2018-01-01

Let Γ be a countable discrete group, and let π:Γ→GL(H) be a representation of Γ by invertible operators on a separable Hilbert space H. We show that the semidirect product group G=H⋊πΓ is SIN (G admits a two-sided invariant metric compatible with its topology) and unitarily representable (G embed...

The finite-dimensional Freeman thesis.

Science.gov (United States)

Rudolph, Lee

2008-06-01

I suggest a modification--and mathematization--of Freeman's thesis on the relations among "perception", "the finite brain", and "the world", based on my recent proposal that the theory of finite topological spaces is both an adequate and a natural mathematical foundation for human psychology.

Finite-size effects on band structure of CdS nanocrystallites studied by positron annihilation

International Nuclear Information System (INIS)

Kar, Soumitra; Biswas, Subhajit; Chaudhuri, Subhadra; Nambissan, P.M.G.

2005-01-01

Quantum confinement effects in nanocrystalline CdS were studied using positrons as spectroscopic probes to explore the defect characteristics. The lifetime of positrons annihilating at the vacancy clusters on nanocrystalline grain surfaces increased remarkably consequent to the onset of such finite-size effects. The Doppler broadened line shape was also found to reflect rather sensitively such distinct changes in the electron momentum redistribution scanned by the positrons, owing to the widening of the band gap. The nanocrystalline sizes of the samples used were confirmed from x-ray diffraction and high resolution transmission electron microscopy and the optical absorption results supported the quantum size effects. Positron annihilation results indicated distinct qualitative changes between CdS nanorods and the bulk sample, notwithstanding the identical x-ray diffraction pattern and close resemblance of the optical absorption spectra. The results are promising in the event of positron annihilation being proved to be a very successful tool for the study of such finite-size effects in semiconductor nanoparticles

Sound radiation from finite surfaces

DEFF Research Database (Denmark)

Brunskog, Jonas

2013-01-01

A method to account for the effect of finite size in acoustic power radiation problem of planar surfaces using spatial windowing is developed. Cremer and Heckl presents a very useful formula for the power radiating from a structure using the spatially Fourier transformed velocity, which combined...... with spatially windowing of a plane waves can be used to take into account the finite size. In the present paper, this is developed by means of a radiation impedance for finite surfaces, that is used instead of the radiation impedance for infinite surfaces. In this way, the spatial windowing is included...

Photon propagators at finite temperature

International Nuclear Information System (INIS)

Yee, J.H.

1982-07-01

We have used the real time formalism to compute the one-loop finite temperature corrections to the photon self energies in spinor and scalar QED. We show that, for a real photon, only the transverse components develop the temperature-dependent masses, while, for an external static electromagnetic field applied to the finite temperature system, only the static electric field is screened by thermal fluctuations. After showing how to compute systematically the imaginary parts of the finite temperature Green functions, we have attempted to give a microscopic interpretation of the imaginary parts of the self energies. (author)

The analysis of crystallographic symmetry types in finite groups

Science.gov (United States)

Sani, Atikah Mohd; Sarmin, Nor Haniza; Adam, Nooraishikin; Zamri, Siti Norziahidayu Amzee

2014-06-01

Undeniably, it is human nature to prefer objects which are considered beautiful. Most consider beautiful as perfection, hence they try to create objects which are perfectly balance in shape and patterns. This creates a whole different kind of art, the kind that requires an object to be symmetrical. This leads to the study of symmetrical objects and pattern. Even mathematicians and ethnomathematicians are very interested with the essence of symmetry. One of these studies were conducted on the Malay traditional triaxial weaving culture. The patterns derived from this technique are symmetrical and this allows for further research. In this paper, the 17 symmetry types in a plane, known as the wallpaper groups, are studied and discussed. The wallpaper groups will then be applied to the triaxial patterns of food cover in Malaysia.

Accelerated finite element elastodynamic simulations using the GPU

Energy Technology Data Exchange (ETDEWEB)

Huthwaite, Peter, E-mail: p.huthwaite@imperial.ac.uk

2014-01-15

An approach is developed to perform explicit time domain finite element simulations of elastodynamic problems on the graphical processing unit, using Nvidia's CUDA. Of critical importance for this problem is the arrangement of nodes in memory, allowing data to be loaded efficiently and minimising communication between the independently executed blocks of threads. The initial stage of memory arrangement is partitioning the mesh; both a well established ‘greedy’ partitioner and a new, more efficient ‘aligned’ partitioner are investigated. A method is then developed to efficiently arrange the memory within each partition. The software is applied to three models from the fields of non-destructive testing, vibrations and geophysics, demonstrating a memory bandwidth of very close to the card's maximum, reflecting the bandwidth-limited nature of the algorithm. Comparison with Abaqus, a widely used commercial CPU equivalent, validated the accuracy of the results and demonstrated a speed improvement of around two orders of magnitude. A software package, Pogo, incorporating these developments, is released open source, downloadable from (http://www.pogo-fea.com/) to benefit the community. -- Highlights: •A novel memory arrangement approach is discussed for finite elements on the GPU. •The mesh is partitioned then nodes are arranged efficiently within each partition. •Models from ultrasonics, vibrations and geophysics are run. •The code is significantly faster than an equivalent commercial CPU package. •Pogo, the new software package, is released open source.

Accelerated finite element elastodynamic simulations using the GPU

International Nuclear Information System (INIS)

Huthwaite, Peter

2014-01-01

An approach is developed to perform explicit time domain finite element simulations of elastodynamic problems on the graphical processing unit, using Nvidia's CUDA. Of critical importance for this problem is the arrangement of nodes in memory, allowing data to be loaded efficiently and minimising communication between the independently executed blocks of threads. The initial stage of memory arrangement is partitioning the mesh; both a well established ‘greedy’ partitioner and a new, more efficient ‘aligned’ partitioner are investigated. A method is then developed to efficiently arrange the memory within each partition. The software is applied to three models from the fields of non-destructive testing, vibrations and geophysics, demonstrating a memory bandwidth of very close to the card's maximum, reflecting the bandwidth-limited nature of the algorithm. Comparison with Abaqus, a widely used commercial CPU equivalent, validated the accuracy of the results and demonstrated a speed improvement of around two orders of magnitude. A software package, Pogo, incorporating these developments, is released open source, downloadable from (http://www.pogo-fea.com/) to benefit the community. -- Highlights: •A novel memory arrangement approach is discussed for finite elements on the GPU. •The mesh is partitioned then nodes are arranged efficiently within each partition. •Models from ultrasonics, vibrations and geophysics are run. •The code is significantly faster than an equivalent commercial CPU package. •Pogo, the new software package, is released open source

Axial anomaly at finite temperature

International Nuclear Information System (INIS)

Chaturvedi, S.; Gupte, Neelima; Srinivasan, V.

1985-01-01

The Jackiw-Bardeen-Adler anomaly for QED 4 and QED 2 are calculated at finite temperature. It is found that the anomaly is independent of temperature. Ishikawa's method [1984, Phys. Rev. Lett. vol. 53 1615] for calculating the quantised Hall effect is extended to finite temperature. (author)

Collaborative Systems – Finite State Machines

Directory of Open Access Journals (Sweden)

Ion IVAN

2011-01-01

Full Text Available In this paper the finite state machines are defined and formalized. There are presented the collaborative banking systems and their correspondence is done with finite state machines. It highlights the role of finite state machines in the complexity analysis and performs operations on very large virtual databases as finite state machines. It builds the state diagram and presents the commands and documents transition between the collaborative systems states. The paper analyzes the data sets from Collaborative Multicash Servicedesk application and performs a combined analysis in order to determine certain statistics. Indicators are obtained, such as the number of requests by category and the load degree of an agent in the collaborative system.

Robust mixed finite element methods to deal with incompressibility in finite strain in an industrial framework

International Nuclear Information System (INIS)

Al-Akhrass, Dina

2014-01-01

Simulations in solid mechanics exhibit several difficulties, as dealing with incompressibility, with nonlinearities due to finite strains, contact laws, or constitutive laws. The basic motivation of our work is to propose efficient finite element methods capable of dealing with incompressibility in finite strain context, and using elements of low order. During the three last decades, many approaches have been proposed in the literature to overcome the incompressibility problem. Among them, mixed formulations offer an interesting theoretical framework. In this work, a three-field mixed formulation (displacement, pressure, volumetric strain) is investigated. In some cases, this formulation can be condensed in a two-field (displacement - pressure) mixed formulation. However, it is well-known that the discrete problem given by the Galerkin finite element technique, does not inherit the 'inf-sup' stability condition from the continuous problem. Hence, the interpolation orders in displacement and pressure have to be chosen in a way to satisfy the Brezzi-Babuska stability conditions when using Galerkin approaches. Interpolation orders must be chosen so as to satisfy this condition. Two possibilities are considered: to use stable finite element satisfying this requirement, or to use finite element that does not satisfy this condition, and to add terms stabilizing the FE Galerkin formulation. The latter approach allows the use of equal order interpolation. In this work, stable finite element P2/P1 and P2/P1/P1 are used as reference, and compared to P1/P1 and P1/P1/P1 formulations stabilized with a bubble function or with a VMS method (Variational Multi-Scale) based on a sub-grid-space orthogonal to the FE space. A finite strain model based on logarithmic strain is selected. This approach is extended to three and two field mixed formulations with stable or stabilized elements. These approaches are validated on academic cases and used on industrial cases. (author)

Development of a three-dimensional neutron transport code DFEM based on the double finite element method

International Nuclear Information System (INIS)

Fujimura, Toichiro

1996-01-01

A three-dimensional neutron transport code DFEM has been developed by the double finite element method to analyze reactor cores with complex geometry as large fast reactors. Solution algorithm is based on the double finite element method in which the space and angle finite elements are employed. A reactor core system can be divided into some triangular and/or quadrangular prism elements, and the spatial distribution of neutron flux in each element is approximated with linear basis functions. As for the angular variables, various basis functions are applied, and their characteristics were clarified by comparison. In order to enhance the accuracy, a general method is derived to remedy the truncation errors at reflective boundaries, which are inherent in the conventional FEM. An adaptive acceleration method and the source extrapolation method were applied to accelerate the convergence of the iterations. The code structure is outlined and explanations are given on how to prepare input data. A sample input list is shown for reference. The eigenvalue and flux distribution for real scale fast reactors and the NEA benchmark problems were presented and discussed in comparison with the results of other transport codes. (author)

‘Our Breadcrumb Trail through the Woods’: Reflections on the Use of a Secret Facebook Group as a Strategy for Surviving and Thriving on the Doctoral Journey

Directory of Open Access Journals (Sweden)

Candice Satchwell

2015-10-01

Full Text Available This article explores the value of attending to the emotional side of the doctoral journey by focusing on the use of a ‘secret’ Facebook group amongst a cohort of EdD (Professional Doctorate in Education students at one English university. Presented as a piece of action research in which the participants created an intervention to address a perceived problem and then reflected on its effectiveness, it is co-authored by the cohort of six students and their tutor. The stresses and loneliness of the doctoral journey have been well documented and constitute the ‘problem’ addressed by this cohort of students. Their inception and use of a Facebook group was a response to challenges experienced in their studies, with the expectation of facilitating peer support. As will be shown this aim was successfully met with enhancements in academic, social, and emotional support. However, unexpected benefits arose from the interactions within the group including a normalization of the challenges of the doctoral quest and the advantage of being able to follow the ‘breadcrumb trail’ found in the group postings as group journal and aid to reflection. Further, both tutors and students have noted the development of a strong sense of ‘cohortness’ and inclination to work collaboratively. Through a process of individual and group reflection on experiences of the intervention, combined with analysis of the content of the postings, this article examines the characteristics of the Facebook intervention and considers some ethical implications. We suggest that key characteristics that have contributed to its success include the student ownership, the protection of the secret format, and the combination of emotionally supportive, academic, and irreverent exchanges between group members. It is hoped that these insights may be useful to future doctoral candidates and their tutors as they negotiate their own way through the doctoral woods.

Mindfulness Plus Reflection Training: Effects on Executive Function in Early Childhood

Directory of Open Access Journals (Sweden)

Philip David Zelazo

2018-02-01

Full Text Available Executive function (EF skills are essential for academic achievement, and poverty-related stress interferes with their development. This pre-test, post-test, follow-up randomized-control trial assessed the impact of an intervention targeting reflection and stress reduction on children's EF skills. Preschool children (N = 218 from schools serving low-income families in two U.S. cities were randomly assigned to one of three options delivered in 30 small-group sessions over 6 weeks: Mindfulness + Reflection training; Literacy training; or Business as Usual (BAU. Sessions were conducted by local teachers trained in a literacy curriculum or Mindfulness + Reflection intervention, which involved calming activities and games that provided opportunities to practice reflection in the context of goal-directed problem solving. EF improved in all groups, but planned contrasts indicated that the Mindfulness + Reflection group significantly outperformed the BAU group at Follow-up (4 weeks post-test. No differences in EF were observed between the BAU and Literacy training groups. Results suggest that a brief, small-group, school-based intervention teaching mindfulness and reflection did not improve EF skills more than literacy training but is promising compared to BAU for improving EF in low-income preschool children several weeks following the intervention.

Pro-Lie Groups: A Survey with Open Problems

Directory of Open Access Journals (Sweden)

Karl H. Hofmann

2015-07-01

Full Text Available A topological group is called a pro-Lie group if it is isomorphic to a closed subgroup of a product of finite-dimensional real Lie groups. This class of groups is closed under the formation of arbitrary products and closed subgroups and forms a complete category. It includes each finite-dimensional Lie group, each locally-compact group that has a compact quotient group modulo its identity component and, thus, in particular, each compact and each connected locally-compact group; it also includes all locally-compact Abelian groups. This paper provides an overview of the structure theory and the Lie theory of pro-Lie groups, including results more recent than those in the authors’ reference book on pro-Lie groups. Significantly, it also includes a review of the recent insight that weakly-complete unital algebras provide a natural habitat for both pro-Lie algebras and pro-Lie groups, indeed for the exponential function that links the two. (A topological vector space is weakly complete if it is isomorphic to a power RX of an arbitrary set of copies of R. This class of real vector spaces is at the basis of the Lie theory of pro-Lie groups. The article also lists 12 open questions connected to pro-Lie groups.

Electrical machine analysis using finite elements

CERN Document Server

Bianchi, Nicola

2005-01-01

OUTLINE OF ELECTROMAGNETIC FIELDSVector AnalysisElectromagnetic FieldsFundamental Equations SummaryReferencesBASIC PRINCIPLES OF FINITE ELEMENT METHODSIntroductionField Problems with Boundary ConditionsClassical Method for the Field Problem SolutionThe Classical Residual Method (Galerkin's Method)The Classical Variational Method (Rayleigh-Ritz's Method)The Finite Element MethodReferencesAPPLICATIONS OF THE FINITE ELEMENT METHOD TO TWO-DIMENSIONAL FIELDSIntroductionLinear Interpolation of the Function fApplication of the Variational MethodSimple Descriptions of Electromagnetic FieldsAppendix: I

What is finiteness? (Abhishek Banerjee) (Indian Institute of Science)

Indian Academy of Sciences (India)

Do finites get enough respect? • Finiteness is easy, no? • Just count whether 1, 2, 3,... • But then we miss out on the true richness of the concept of finitness. • There's more finiteness around. In fact, finiteness is what helps us really understand things. 5 ...

Reflection and Transmission of P-Waves in an Intermediate Layer Lying Between Two Semi-infinite Media

Science.gov (United States)

Singh, Pooja; Chattopadhyay, Amares; Srivastava, Akanksha; Singh, Abhishek Kumar

2018-05-01

With a motivation to gain physical insight of reflection as well as transmission phenomena in frozen (river/ocean) situation for example in Antarctica and other coldest place on Earth, the present article undertakes the analysis of reflection and transmission of a plane wave at the interfaces of layered structured comprised of a water layer of finite thickness sandwiched between an upper half-space constituted of ice and a lower isotropic elastic half-space, which may be useful in geophysical exploration in such conditions. A closed form expression of reflection/transmission coefficients of reflected and transmitted waves has been derived in terms of angles of incidence, propagation vector, displacement vector and elastic constants of the media. Expressions corresponding to the energy partition of various reflected and transmitted waves have also been established analytically. It has been remarkably shown that the law of conservation of energy holds good in the entire reflection and transmission phenomena for different angles of incidence. A numerical examples were performed so to graphically portray the analytical findings. Further the deduced results are validated with the pre-established classical results.

Centralizers of maximal regular subgroups in simple Lie groups and relative congruence classes of representations

Energy Technology Data Exchange (ETDEWEB)

Larouche, M [Departement de Mathematiques et Statistique, Universite de Montreal, 2920 chemin de la Tour, Montreal, Quebec H3T 1J4 (Canada); Lemire, F W [Department of Mathematics, University of Windsor, Windsor, Ontario (Canada); Patera, J, E-mail: larouche@dms.umontreal.ca, E-mail: lemire@uwindsor.ca, E-mail: patera@crm.umontreal.ca [Centre de Recherches Mathematiques, Universite de Montreal, CP 6128-Centre ville, Montreal, Quebec H3C 3J7 (Canada)

2011-10-14

In this paper, we present a new, uniform and comprehensive description of centralizers of the maximal regular subgroups in compact simple Lie groups of all types and ranks. The centralizer is either a direct product of finite cyclic groups, a continuous group of rank 1, or a product, not necessarily direct, of a continuous group of rank 1 with a finite cyclic group. Explicit formulas for the action of such centralizers on irreducible representations of the simple Lie algebras are given. (paper)

Finite Element Analysis of Simple Rectangular Microstrip Sensor for Determination Moisture Content of Hevea Rubber Latex

Science.gov (United States)

Yahaya, NZ; Ramli, MR; Razak, NNANA; Abbas, Z.

2018-04-01

The Finite Element Method, FEM has been successfully used to model a simple rectangular microstrip sensor to determine the moisture content of Hevea rubber latex. The FEM simulation of sensor and samples was implemented by using COMSOL Multiphysics software. The simulation includes the calculation of magnitude and phase of reflection coefficient and was compared to analytical method. The results show a good agreement in finding the magnitude and phase of reflection coefficient when compared with analytical results. Field distributions of both the unloaded sensor as well as the sensor loaded with different percentages of moisture content were visualized using FEM in conjunction with COMSOL software. The higher the amount of moisture content in the sample the more the electric loops were observed.

Finite Metric Spaces of Strictly negative Type

DEFF Research Database (Denmark)

Hjorth, Poul G.

If a finite metric space is of strictly negative type then its transfinite diameter is uniquely realized by an infinite extent (“load vector''). Finite metric spaces that have this property include all trees, and all finite subspaces of Euclidean and Hyperbolic spaces. We prove that if the distance...

[Who benefits from systemic therapy with a reflecting team?].

Science.gov (United States)

Höger, C; Temme, M; Geiken, G

1994-03-01

In an evaluation study we investigated the effectiveness of the reflecting team approach compared to eclectic child psychiatric treatment in an outpatient setting and the indications for each type of treatment. The relationship between treatment outcome and diagnostic data obtained with the Multi-axial Classification Scheme was examined in 22 families treated with the reflecting team approach and in a second group of families matched on all important sociodemographic and diagnostic variables but receiving eclectic treatment. No difference was found between the two groups regarding symptom improvement or changes in family functioning. Regarding satisfaction with treatment, the reflecting team approach was superior to the eclectic modality. In the reflecting team group parental mental disorder and inadequate intra-familial communication (according to the new fifth axis of the Multi-axial Classification Scheme) had a negative effect on outcome.

Probabilistic finite elements

Science.gov (United States)

Belytschko, Ted; Wing, Kam Liu

1987-01-01

In the Probabilistic Finite Element Method (PFEM), finite element methods have been efficiently combined with second-order perturbation techniques to provide an effective method for informing the designer of the range of response which is likely in a given problem. The designer must provide as input the statistical character of the input variables, such as yield strength, load magnitude, and Young's modulus, by specifying their mean values and their variances. The output then consists of the mean response and the variance in the response. Thus the designer is given a much broader picture of the predicted performance than with simply a single response curve. These methods are applicable to a wide class of problems, provided that the scale of randomness is not too large and the probabilistic density functions possess decaying tails. By incorporating the computational techniques we have developed in the past 3 years for efficiency, the probabilistic finite element methods are capable of handling large systems with many sources of uncertainties. Sample results for an elastic-plastic ten-bar structure and an elastic-plastic plane continuum with a circular hole subject to cyclic loadings with the yield stress on the random field are given.

Group Leader Reflections on Their Training and Experience: Implications for Group Counselor Educators and Supervisors

Science.gov (United States)

Ohrt, Jonathan H.; Ener, Elizabeth; Porter, Jessica; Young, Tabitha L.

2014-01-01

Effective group leaders possess specialized counseling skills and abilities; however, attention to group leadership training appears to be lagging behind that of individual counseling. In this phenomenological study we explored group leaders' perceptions of their training and experience. Twenty-two professional counselors participated in…

Finite cluster renormalization group for disordered two-dimensional systems

International Nuclear Information System (INIS)

El Kenz, A.

1987-09-01

A new type of renormalization group theory using the generalized Callen identities is exploited in the study of the disordered systems. Bond diluted and frustrated Ising systems on a square lattice are analyzed with this new scheme. (author). 9 refs, 2 figs, 2 tabs

From research to self-reflection: learning about ourselves as academics through a support group's resistance to our intervention.

Science.gov (United States)

Scherr, Courtney Lynam; Mattson, Marifran

2012-01-01

Purdue University's Center for Healthcare Engineering developed a computer-assisted technology hub (CATHUB) designed to aid individuals with disabilities. Upon realizing the lack of input from the very individuals they were trying to help, Marifran approached the developers of CATHUB and offered to engage a group of amputees to aid in the design and implementation of the hub. In this essay, Courtney and Marifran recount, each from their own perspective, their experiences working with Amputees in Action as participants in their research project. Ultimately the researchers discovered their research agenda was not compatible with the amputees' needs, resulting in enlightened self-reflection by the researchers and abandonment of the research project.

Examining the cost efficiency of Chinese hydroelectric companies using a finite mixture model

International Nuclear Information System (INIS)

Barros, Carlos Pestana; Chen, Zhongfei; Managi, Shunsuke; Antunes, Olinda Sequeira

2013-01-01

This paper evaluates the operational activities of Chinese hydroelectric power companies over the period 2000–2010 using a finite mixture model that controls for unobserved heterogeneity. In so doing, a stochastic frontier latent class model, which allows for the existence of different technologies, is adopted to estimate cost frontiers. This procedure not only enables us to identify different groups among the hydro-power companies analysed, but also permits the analysis of their cost efficiency. The main result is that three groups are identified in the sample, each equipped with different technologies, suggesting that distinct business strategies need to be adapted to the characteristics of China's hydro-power companies. Some managerial implications are developed. - Highlights: ► This paper evaluates the operational activities of Chinese electricity hydric companies. ► This study uses data from 2000 to 2010 using a finite mixture model. ► The model procedure identifies different groups of Chinese hydric companies analysed. ► Three groups are identified in the sample, each equipped with completely different “technologies”. ► This suggests that distinct business strategies need to be adapted to the characteristics of the hydric companies

[Social crisis, spontaneous groups and group order].

Science.gov (United States)

Edelman, Lucila; Kordon, Diana

2002-12-01

Argentina has gone through very difficult times during the last years and, in particularly, new kinds of social practices have emerged in order to cope with the crisis. This situation demands and urges a new type of reflection upon the double role of groups, as tools to transform reality and as a way to elaborate those processes regarding subjectivity. In this paper we analyse some topics regarding the groupal field (considering spontaneous groups as well as groupal devices that allow to elaborate the crisis). We consider social bond to be the condition of possibility for the existence of the psyche and of time continuity, and that it also makes possible personal and social elaboration of trauma, crisis and social catastrophe. We develop some aspects of an specific device (the reflection group), which we have already depicted in another moment, showing it's usefulness to cope with social crisis and to promote the subjective elaboration of crisis.

Manipulatable Andreev reflection due to the interplay between the DIII-class topological and s-wave superconductors

Science.gov (United States)

Wang, Xiao-Qi; Yi, Guang-Yu; Han, Yu; Jiang, Cui; Gong, Wei-Jiang

2018-07-01

We construct one mesoscopic circuit in which one quantum dot couples to one DIII-class topological superconductor and one s-wave superconductor, in addition to its connection with the metallic lead. And then, the Andreev reflection current in the metallic lead is evaluated. It is found that the two kinds of superconductors drive the Andreev reflection in the constructive manner. Next as finite superconducting phase difference is taken into account, the Andreev reflection oscillates in period π/2, and it can be suppressed in the low-energy region if the superconducting phase difference is (n + 1/2) π/2 (n ∈ Integer). Such a result is almost independent of the increase of the intradot Coulomb interaction. Therefore, this structure can assist to realize the manipulation of the Andreev reflection. Also, the result in this work provides useful information for understanding the property of the DIII-class topological superconductor.

Implicit and fully implicit exponential finite difference methods

Indian Academy of Sciences (India)

Burgers' equation; exponential finite difference method; implicit exponential finite difference method; ... This paper describes two new techniques which give improved exponential finite difference solutions of Burgers' equation. ... Current Issue

The Weyl group of the Cuntz algebra

DEFF Research Database (Denmark)

Conti, Roberto; Hong, Jeong Hee; Szymanski, Wojciech

2012-01-01

The Weyl group of the Cuntz algebra O_n is investigated. This is (isomorphic to) the group of polynomial automorphisms lambda_u of O_n, namely those induced by unitaries u that can be written as finite sums of words in the canonical generating isometries S_i and their adjoints. A necessary...

Delocalized SYZ mirrors and confronting top-down SU(3)-structure holographic meson masses at finite g and N{sub c} with P(article) D(ata) G(roup) values

Energy Technology Data Exchange (ETDEWEB)

Yadav, Vikas; Sil, Karunava [Indian Institute of Technology, Department of Physics, Roorkee, Uttarakhand (India); Misra, Aalok [Indian Institute of Technology, Department of Physics, Roorkee, Uttarakhand (India); McGill University, Physics Department, Montreal, QC (Canada)

2017-10-15

Meson spectroscopy at finite gauge coupling - whereat any perturbative QCD computation would break down - and finite number of colors, from a top-down holographic string model, has thus far been entirely missing in the literature. This paper fills this gap. Using the delocalized type IIA SYZ mirror (with SU(3) structure) of the holographic type IIB dual of large-N thermal QCD of Mia et al. (Nucl Phys B 839:187. arXiv:0902.1540 [hep-th], 2010) as constructed in Dhuria and Misra (JHEP 1311:001. arXiv:1306.4339 [hep-th], 2013) at finite coupling and number of colors (N{sub c} = number of D5(D5)-branes wrapping a vanishing two-cycle in the top-down holographic construct of Mia et al. (Nucl Phys B 839:187. arXiv:0902.1540 [hep-th], 2010) = O(1) in the IR in the MQGP limit of Dhuria and Misra (JHEP 1311:001. arXiv:1306.4339 [hep-th], 2013) at the end of a Seiberg-duality cascade), we obtain analytical (not just numerical) expressions for the vector and scalar meson spectra and compare our results with previous calculations of Sakai and Sugimoto (Prog Theor Phys 113:843. doi:10.1143/PTP.113.843 arXiv:hep-th/0412141, 2005) and Dasgupta et al. (JHEP 1507:122. doi:10.1007/JHEP07(2015)122 arXiv:1409.0559 [hep-th], 2015), and we obtain a closer match with the Particle Data Group (PDG) results of Olive et al. (Particle Data Group) (Chin Phys C 38:090001, 2014). Through explicit computations, we verify that the vector and scalar meson spectra obtained by the gravity dual with a black hole for all temperatures (small and large) are nearly isospectral with the spectra obtained by a thermal gravity dual valid for only low temperatures; the isospectrality is much closer for vector mesons than scalar mesons. The black-hole gravity dual (with a horizon radius smaller than the deconfinement scale) also provides the expected large-N suppressed decrease in vector meson mass with increase of temperature. (orig.)

Symmetries of the second-difference matrix and the finite Fourier transform

International Nuclear Information System (INIS)

Aguilar, A.; Wolf, K.B.

1979-01-01

The finite Fourier transformation is well known to diagonalize the second-difference matrix and has been thus applied extensively to describe finite crystal lattices and electric networks. In setting out to find all transformations having this property, we obtain a multiparameter class of them. While permutations and unitary scaling of the eigenvectors constitute the trivial freedom of choice common to all diagonalization processes, the second-difference matrix has a larger symmetry group among whose elements we find the dihedral manifest symmetry transformations of the lattice. The latter are nevertheless sufficient for the unique specification of eigenvectors in various symmetry-adapted bases for the constrained lattice. The free symmetry parameters are shown to lead to a complete set of conserved quantities for the physical lattice motion. (author)

Prediction and measurement of the reflection of the fundamental anti-symmetric Lamb wave from cracks and notches

International Nuclear Information System (INIS)

Lowe, M.J.S.; Cawley, P.; Kao, J-Y; Diligent, O.

2000-01-01

The interaction of the fundamental antisymmetric Lamb wave (a o ) with cracks and with notches of different depth and width has been investigated both experimentally and by finite element analysis. Excellent agreement between the predictions and the measurements has been obtained. It has been shown that the reflection coefficient is a function of both the notch width to wavelength and notch depth to wavelength ratios. Both the relationship between the reflection coefficient and notch, depth, and the frequency dependence of the reflection coefficient, are very different for the a o mode compared to the s o mode which was studied earlier. Physical insight into the reasons for the different behavior is given by examination of the stress fields and opening displacements at the crack or notch

Finite-time tracking control for multiple non-holonomic mobile robots based on visual servoing

Science.gov (United States)

Ou, Meiying; Li, Shihua; Wang, Chaoli

2013-12-01

This paper investigates finite-time tracking control problem of multiple non-holonomic mobile robots via visual servoing. It is assumed that the pinhole camera is fixed to the ceiling, and camera parameters are unknown. The desired reference trajectory is represented by a virtual leader whose states are available to only a subset of the followers, and the followers have only interaction. First, the camera-objective visual kinematic model is introduced by utilising the pinhole camera model for each mobile robot. Second, a unified tracking error system between camera-objective visual servoing model and desired reference trajectory is introduced. Third, based on the neighbour rule and by using finite-time control method, continuous distributed cooperative finite-time tracking control laws are designed for each mobile robot with unknown camera parameters, where the communication topology among the multiple mobile robots is assumed to be a directed graph. Rigorous proof shows that the group of mobile robots converges to the desired reference trajectory in finite time. Simulation example illustrates the effectiveness of our method.

Enhancing Self-Practice/Self-Reflection (SP/SR) approach to cognitive behaviour training through the use of reflective blogs.

Science.gov (United States)

Farrand, Paul; Perry, Jon; Linsley, Sue

2010-07-01

Self-Practice/Self-Reflection (SP/SR) is increasingly beginning to feature as a central component of CBT training programmes (Bennett-Levy et al., 2001). Programmes including a reflective element, however, are not unproblematic and it has been documented that simply setting time aside for reflection does not necessarily result in trainees using such time to reflect. Such limitations may be overcome by including a requirement to post reflections on reflective blogs. To examine the effect that a requirement to contribute to a reflective blog had upon a SP/SR approach to CBT training. A focus group methodology was adopted with data analyzed using a general inductive qualitative approach. The requirement to use blogs to reflect upon the self-practice of CBT techniques enhanced SP/SR, established a learning community, and improved course supervision, although some technical difficulties arose. Consideration should be given towards using reflective blogs to support a SP/SR approach to CBT training. Benefits afforded by the use of reflective blogs further establish SP/SR as a valid and flexible training approach.

Performance and scalability of finite-difference and finite-element wave-propagation modeling on Intel's Xeon Phi

NARCIS (Netherlands)

Zhebel, E.; Minisini, S.; Kononov, A.; Mulder, W.A.

2013-01-01

With the rapid developments in parallel compute architectures, algorithms for seismic modeling and imaging need to be reconsidered in terms of parallelization. The aim of this paper is to compare scalability of seismic modeling algorithms: finite differences, continuous mass-lumped finite elements

Modelling of Evaporator in Waste Heat Recovery System using Finite Volume Method and Fuzzy Technique

Directory of Open Access Journals (Sweden)

Jahedul Islam Chowdhury

2015-12-01

Full Text Available The evaporator is an important component in the Organic Rankine Cycle (ORC-based Waste Heat Recovery (WHR system since the effective heat transfer of this device reflects on the efficiency of the system. When the WHR system operates under supercritical conditions, the heat transfer mechanism in the evaporator is unpredictable due to the change of thermo-physical properties of the fluid with temperature. Although the conventional finite volume model can successfully capture those changes in the evaporator of the WHR process, the computation time for this method is high. To reduce the computation time, this paper develops a new fuzzy based evaporator model and compares its performance with the finite volume method. The results show that the fuzzy technique can be applied to predict the output of the supercritical evaporator in the waste heat recovery system and can significantly reduce the required computation time. The proposed model, therefore, has the potential to be used in real time control applications.

Eisenstein series for infinite-dimensional U-duality groups

Science.gov (United States)

Fleig, Philipp; Kleinschmidt, Axel

2012-06-01

We consider Eisenstein series appearing as coefficients of curvature corrections in the low-energy expansion of type II string theory four-graviton scattering amplitudes. We define these Eisenstein series over all groups in the E n series of string duality groups, and in particular for the infinite-dimensional Kac-Moody groups E 9, E 10 and E 11. We show that, remarkably, the so-called constant term of Kac-Moody-Eisenstein series contains only a finite number of terms for particular choices of a parameter appearing in the definition of the series. This resonates with the idea that the constant term of the Eisenstein series encodes perturbative string corrections in BPS-protected sectors allowing only a finite number of corrections. We underpin our findings with an extensive discussion of physical degeneration limits in D < 3 space-time dimensions.

Density character of subgroups of topological groups

OpenAIRE

Leiderman, Arkady; Morris, Sidney A.; Tkachenko, Mikhail G.

2015-01-01

A subspace Y of a separable metrizable space X is separable, but without X metrizable this is not true even If Y is a closed linear subspace of a topological vector space X. K.H. Hofmann and S.A. Morris introduced the class of pro-Lie groups which consists of projective limits of finite-dimensional Lie groups and proved that it contains all compact groups, locally compact abelian groups and connected locally compact groups and is closed under products and closed subgroups. A topological group...

An introduction to finite projective planes

CERN Document Server

Albert, Abraham Adrian

2015-01-01

Geared toward both beginning and advanced undergraduate and graduate students, this self-contained treatment offers an elementary approach to finite projective planes. Following a review of the basics of projective geometry, the text examines finite planes, field planes, and coordinates in an arbitrary plane. Additional topics include central collineations and the little Desargues' property, the fundamental theorem, and examples of finite non-Desarguesian planes.Virtually no knowledge or sophistication on the part of the student is assumed, and every algebraic system that arises is defined and

A least squares principle unifying finite element, finite difference and nodal methods for diffusion theory

International Nuclear Information System (INIS)

Ackroyd, R.T.

1987-01-01

A least squares principle is described which uses a penalty function treatment of boundary and interface conditions. Appropriate choices of the trial functions and vectors employed in a dual representation of an approximate solution established complementary principles for the diffusion equation. A geometrical interpretation of the principles provides weighted residual methods for diffusion theory, thus establishing a unification of least squares, variational and weighted residual methods. The complementary principles are used with either a trial function for the flux or a trial vector for the current to establish for regular meshes a connection between finite element, finite difference and nodal methods, which can be exact if the mesh pitches are chosen appropriately. Whereas the coefficients in the usual nodal equations have to be determined iteratively, those derived via the complementary principles are given explicitly in terms of the data. For the further development of the connection between finite element, finite difference and nodal methods, some hybrid variational methods are described which employ both a trial function and a trial vector. (author)

FINITE ELEMENT MODEL FOR PREDICTING RESIDUAL ...

African Journals Online (AJOL)

FINITE ELEMENT MODEL FOR PREDICTING RESIDUAL STRESSES IN ... the transverse residual stress in the x-direction (σx) had a maximum value of 375MPa ... the finite element method are in fair agreement with the experimental results.

Quantum groups, non-commutative differential geometry and applications

International Nuclear Information System (INIS)

Schupp, P.; California Univ., Berkeley, CA

1993-01-01

The topic of this thesis is the development of a versatile and geometrically motivated differential calculus on non-commutative or quantum spaces, providing powerful but easy-to-use mathematical tools for applications in physics and related sciences. A generalization of unitary time evolution is proposed and studied for a simple 2-level system, leading to non-conservation of microscopic entropy, a phenomenon new to quantum mechanics. A Cartan calculus that combines functions, forms, Lie derivatives and inner derivations along general vector fields into one big algebra is constructed for quantum groups and then extended to quantum planes. The construction of a tangent bundle on a quantum group manifold and an BRST type approach to quantum group gauge theory are given as further examples of applications. The material is organized in two parts: Part I studies vector fields on quantum groups, emphasizing Hopf algebraic structures, but also introducing a ''quantum geometric'' construction. Using a generalized semi-direct product construction we combine the dual Hopf algebras A of functions and U of left-invariant vector fields into one fully bicovariant algebra of differential operators. The pure braid group is introduced as the commutant of Δ(U). It provides invariant maps A → U and thereby bicovariant vector fields, casimirs and metrics. This construction allows the translation of undeformed matrix expressions into their less obvious quantum algebraic counter parts. We study this in detail for quasitriangular Hopf algebras, giving the determinant and orthogonality relation for the ''reflection'' matrix. Part II considers the additional structures of differential forms and finitely generated quantum Lie algebras -- it is devoted to the construction of the Cartan calculus, based on an undeformed Cartan identity

Closed 1-forms in topology and geometric group theory

Energy Technology Data Exchange (ETDEWEB)

Farber, Michael; Schuetz, Dirk [University of Durham, Durham (United Kingdom); Geoghegan, Ross [State University of New York, New York (United States)

2010-01-01

In this article we describe relations of the topology of closed 1-forms to the group-theoretic invariants of Bieri-Neumann-Strebel-Renz. Starting with a survey, we extend these Sigma invariants to finite CW-complexes and show that many properties of the group-theoretic version have analogous statements. In particular, we show the relation between Sigma invariants and finiteness properties of certain infinite covering spaces. We also discuss applications of these invariants to the Lusternik-Schnirelmann category of a closed 1-form and to the existence of a non-singular closed 1-form in a given cohomology class on a high-dimensional closed manifold. Bibliography: 32 titles.

Optimal Black-Box Secret Sharing over Arbitrary Abelian Groups

DEFF Research Database (Denmark)

Cramer, Ronald; Fehr, Serge

2002-01-01

A black-box secret sharing scheme for the threshold access structure T t,n is one which works over any finite Abelian group G. Briefly, such a scheme differs from an ordinary linear secret sharing scheme (over, say, a given finite field) in that distribution matrix and reconstruction vectors...... are defined over ℤ and are designed independently of the group G from which the secret and the shares are sampled. This means that perfect completeness and perfect privacy are guaranteed regardless of which group G is chosen. We define the black-box secret sharing problem as the problem of devising......, for an arbitrary given T t,n , a scheme with minimal expansion factor, i.e., where the length of the full vector of shares divided by the number of players n is minimal. Such schemes are relevant for instance in the context of distributed cryptosystems based on groups with secret or hard to compute group order...

Characterization of finite spaces having dispersion points

International Nuclear Information System (INIS)

Al-Bsoul, A. T

1997-01-01

In this paper we shall characterize the finite spaces having dispersion points. Also, we prove that the dispersion point of a finite space with a dispersion points fixed under all non constant continuous functions which answers the question raised by J. C obb and W. Voxman in 1980 affirmatively for finite space. Some open problems are given. (author). 16 refs

Finite element methods a practical guide

CERN Document Server

Whiteley, Jonathan

2017-01-01

This book presents practical applications of the finite element method to general differential equations. The underlying strategy of deriving the finite element solution is introduced using linear ordinary differential equations, thus allowing the basic concepts of the finite element solution to be introduced without being obscured by the additional mathematical detail required when applying this technique to partial differential equations. The author generalizes the presented approach to partial differential equations which include nonlinearities. The book also includes variations of the finite element method such as different classes of meshes and basic functions. Practical application of the theory is emphasised, with development of all concepts leading ultimately to a description of their computational implementation illustrated using Matlab functions. The target audience primarily comprises applied researchers and practitioners in engineering, but the book may also be beneficial for graduate students.

Finite Volumes for Complex Applications VII

CERN Document Server

Ohlberger, Mario; Rohde, Christian

2014-01-01

The methods considered in the 7th conference on "Finite Volumes for Complex Applications" (Berlin, June 2014) have properties which offer distinct advantages for a number of applications. The second volume of the proceedings covers reviewed contributions reporting successful applications in the fields of fluid dynamics, magnetohydrodynamics, structural analysis, nuclear physics, semiconductor theory and other topics. The finite volume method in its various forms is a space discretization technique for partial differential equations based on the fundamental physical principle of conservation. Recent decades have brought significant success in the theoretical understanding of the method. Many finite volume methods preserve further qualitative or asymptotic properties, including maximum principles, dissipativity, monotone decay of free energy, and asymptotic stability. Due to these properties, finite volume methods belong to the wider class of compatible discretization methods, which preserve qualitative propert...

A multigrid solution method for mixed hybrid finite elements

Energy Technology Data Exchange (ETDEWEB)

Schmid, W. [Universitaet Augsburg (Germany)

1996-12-31

We consider the multigrid solution of linear equations arising within the discretization of elliptic second order boundary value problems of the form by mixed hybrid finite elements. Using the equivalence of mixed hybrid finite elements and non-conforming nodal finite elements, we construct a multigrid scheme for the corresponding non-conforming finite elements, and, by this equivalence, for the mixed hybrid finite elements, following guidelines from Arbogast/Chen. For a rectangular triangulation of the computational domain, this non-conforming schemes are the so-called nodal finite elements. We explicitly construct prolongation and restriction operators for this type of non-conforming finite elements. We discuss the use of plain multigrid and the multilevel-preconditioned cg-method and compare their efficiency in numerical tests.

Moving mesh finite element method for finite time extinction of distributed parameter systems with positive exponential feedback

International Nuclear Information System (INIS)

Garnadi, A.D.

1997-01-01

In the distributed parameter systems with exponential feedback, non-global existence of solution is not always exist. For some positive initial values, there exist finite time T such that the solution goes to infinity, i.e. finite time extinction or blow-up. Here is present a numerical solution using Moving Mesh Finite Element to solve the distributed parameter systems with exponential feedback close to blow-up time. The numerical behavior of the mesh close to the time of extinction is the prime interest in this study

Finite Markov processes and their applications

CERN Document Server

Iosifescu, Marius

2007-01-01

A self-contained treatment of finite Markov chains and processes, this text covers both theory and applications. Author Marius Iosifescu, vice president of the Romanian Academy and director of its Center for Mathematical Statistics, begins with a review of relevant aspects of probability theory and linear algebra. Experienced readers may start with the second chapter, a treatment of fundamental concepts of homogeneous finite Markov chain theory that offers examples of applicable models.The text advances to studies of two basic types of homogeneous finite Markov chains: absorbing and ergodic ch

Finite-volume scheme for anisotropic diffusion

Energy Technology Data Exchange (ETDEWEB)

Es, Bram van, E-mail: bramiozo@gmail.com [Centrum Wiskunde & Informatica, P.O. Box 94079, 1090GB Amsterdam (Netherlands); FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, The Netherlands" 1 (Netherlands); Koren, Barry [Eindhoven University of Technology (Netherlands); Blank, Hugo J. de [FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, The Netherlands" 1 (Netherlands)

2016-02-01

In this paper, we apply a special finite-volume scheme, limited to smooth temperature distributions and Cartesian grids, to test the importance of connectivity of the finite volumes. The area of application is nuclear fusion plasma with field line aligned temperature gradients and extreme anisotropy. We apply the scheme to the anisotropic heat-conduction equation, and compare its results with those of existing finite-volume schemes for anisotropic diffusion. Also, we introduce a general model adaptation of the steady diffusion equation for extremely anisotropic diffusion problems with closed field lines.

Finite element analysis of piezoelectric materials

International Nuclear Information System (INIS)

Lowrie, F.; Stewart, M.; Cain, M.; Gee, M.

1999-01-01

This guide is intended to help people wanting to do finite element analysis of piezoelectric materials by answering some of the questions that are peculiar to piezoelectric materials. The document is not intended as a complete beginners guide for finite element analysis in general as this is better dealt with by the individual software producers. The guide is based around the commercial package ANSYS as this is a popular package amongst piezoelectric material users, however much of the information will still be useful to users of other finite element codes. (author)

From Finite Time to Finite Physical Dimensions Thermodynamics: The Carnot Engine and Onsager's Relations Revisited

Science.gov (United States)

Feidt, Michel; Costea, Monica

2018-04-01

Many works have been devoted to finite time thermodynamics since the Curzon and Ahlborn [1] contribution, which is generally considered as its origin. Nevertheless, previous works in this domain have been revealed [2], [3], and recently, results of the attempt to correlate Finite Time Thermodynamics with Linear Irreversible Thermodynamics according to Onsager's theory were reported [4]. The aim of the present paper is to extend and improve the approach relative to thermodynamic optimization of generic objective functions of a Carnot engine with linear response regime presented in [4]. The case study of the Carnot engine is revisited within the steady state hypothesis, when non-adiabaticity of the system is considered, and heat loss is accounted for by an overall heat leak between the engine heat reservoirs. The optimization is focused on the main objective functions connected to engineering conditions, namely maximum efficiency or power output, except the one relative to entropy that is more fundamental. Results given in reference [4] relative to the maximum power output and minimum entropy production as objective function are reconsidered and clarified, and the change from finite time to finite physical dimension was shown to be done by the heat flow rate at the source. Our modeling has led to new results of the Carnot engine optimization and proved that the primary interest for an engineer is mainly connected to what we called Finite Physical Dimensions Optimal Thermodynamics.

Psychiatric nursing menbers' reflections on participating in group-based clinical supervision

DEFF Research Database (Denmark)

Buus, Niels; Angel, Sanne; Traynor, Michael

2011-01-01

This paper is a report of an interview study exploring psychiatric hospital nursing staff members' reflections on participating in supervision. Clinical supervision is a pedagogical process designed to direct, develop, and support clinical nurses. Participation rates in clinical supervision...... they influence participation rates. Twenty-two psychiatric hospital nursing staff members were interviewed with a semistructured interview guide. Interview transcripts were interpreted by means of Ricoeur's hermeneutic method. The respondents understood clinical supervision to be beneficial, but with very...

Complex saddle points in QCD at finite temperature and density

Science.gov (United States)

Nishimura, Hiromichi; Ogilvie, Michael C.; Pangeni, Kamal

2014-08-01

The sign problem in QCD at finite temperature and density leads naturally to the consideration of complex saddle points of the action or effective action. The global symmetry CK of the finite-density action, where C is charge conjugation and K is complex conjugation, constrains the eigenvalues of the Polyakov loop operator P at a saddle point in such a way that the action is real at a saddle point, and net color charge is zero. The values of TrFP and TrFP† at the saddle point are real but not identical, indicating the different free energy cost associated with inserting a heavy quark versus an antiquark into the system. At such complex saddle points, the mass matrix associated with Polyakov loops may have complex eigenvalues, reflecting oscillatory behavior in color-charge densities. We illustrate these properties with a simple model which includes the one-loop contribution of gluons and two flavors of massless quarks moving in a constant Polyakov loop background. Confinement-deconfinement effects are modeled phenomenologically via an added potential term depending on the Polyakov loop eigenvalues. For sufficiently large temperature T and quark chemical potential μ, the results obtained reduce to those of perturbation theory at the complex saddle point. These results may be experimentally relevant for the compressed baryonic matter experiment at FAIR.

Finite temperature field theory

CERN Document Server

Das, Ashok

1997-01-01

This book discusses all three formalisms used in the study of finite temperature field theory, namely the imaginary time formalism, the closed time formalism and thermofield dynamics. Applications of the formalisms are worked out in detail. Gauge field theories and symmetry restoration at finite temperature are among the practical examples discussed in depth. The question of gauge dependence of the effective potential and the Nielsen identities are explained. The nonrestoration of some symmetries at high temperature (such as supersymmetry) and theories on nonsimply connected space-times are al

Group theoretic reduction of Laplacian dynamical problems on fractal lattices

International Nuclear Information System (INIS)

Schwalm, W.A.; Schwalm, M.K.; Giona, M.

1997-01-01

Discrete forms of the Schroedinger equation, the diffusion equation, the linearized Landau-Ginzburg equation, and discrete models for vibrations and spin dynamics belong to a class of Laplacian-based finite difference models. Real-space renormalization of such models on finitely ramified regular fractals is known to give exact recursion relations. It is shown that these recursions commute with Lie groups representing continuous symmetries of the discrete models. Each such symmetry reduces the order of the renormalization recursions by one, resulting in a system of recursions with one fewer variable. Group trajectories are obtained from inverse images of fixed and invariant sets of the recursions. A subset of the Laplacian finite difference models can be mapped by change of boundary conditions and time dependence to a diffusion problem with closed boundaries. In such cases conservation of mass simplifies the group flow and obtaining the groups becomes easier. To illustrate this, the renormalization recursions for Green functions on four standard examples are decoupled. The examples are (1) the linear chain, (2) an anisotropic version of Dhar close-quote s 3-simplex, similar to a model dealt with by Hood and Southern, (3) the fourfold coordinated Sierpiacute nski lattice of Rammal and of Domany et al., and (4) a form of the Vicsek lattice. Prospects for applying the group theoretic method to more general dynamical systems are discussed. copyright 1997 The American Physical Society

Distributed finite-time trajectory tracking control for multiple nonholonomic mobile robots with uncertainties and external disturbances

Science.gov (United States)

Ou, Meiying; Sun, Haibin; Gu, Shengwei; Zhang, Yangyi

2017-11-01

This paper investigates the distributed finite-time trajectory tracking control for a group of nonholonomic mobile robots with time-varying unknown parameters and external disturbances. At first, the tracking error system is derived for each mobile robot with the aid of a global invertible transformation, which consists of two subsystems, one is a first-order subsystem and another is a second-order subsystem. Then, the two subsystems are studied respectively, and finite-time disturbance observers are proposed for each robot to estimate the external disturbances. Meanwhile, distributed finite-time tracking controllers are developed for each mobile robot such that all states of each robot can reach the desired value in finite time, where the desired reference value is assumed to be the trajectory of a virtual leader whose information is available to only a subset of the followers, and the followers are assumed to have only local interaction. The effectiveness of the theoretical results is finally illustrated by numerical simulations.

Finite Size Scaling of Perceptron

OpenAIRE

Korutcheva, Elka; Tonchev, N.

2000-01-01

We study the first-order transition in the model of a simple perceptron with continuous weights and large, bit finite value of the inputs. Making the analogy with the usual finite-size physical systems, we calculate the shift and the rounding exponents near the transition point. In the case of a general perceptron with larger variety of inputs, the analysis only gives bounds for the exponents.

Reflectivity of 1D photonic crystals: A comparison of computational schemes with experimental results

Science.gov (United States)

Pérez-Huerta, J. S.; Ariza-Flores, D.; Castro-García, R.; Mochán, W. L.; Ortiz, G. P.; Agarwal, V.

2018-04-01

We report the reflectivity of one-dimensional finite and semi-infinite photonic crystals, computed through the coupling to Bloch modes (BM) and through a transfer matrix method (TMM), and their comparison to the experimental spectral line shapes of porous silicon (PS) multilayer structures. Both methods reproduce a forbidden photonic bandgap (PBG), but slowly-converging oscillations are observed in the TMM as the number of layers increases to infinity, while a smooth converged behavior is presented with BM. The experimental reflectivity spectra is in good agreement with the TMM results for multilayer structures with a small number of periods. However, for structures with large amount of periods, the measured spectral line shapes exhibit better agreement with the smooth behavior predicted by BM.

Finite automata over magmas: models and some applications in Cryptography

Directory of Open Access Journals (Sweden)

Volodymyr V. Skobelev

2018-05-01

Full Text Available In the paper the families of finite semi-automata and reversible finite Mealy and Moore automata over finite magmas are defined and analyzed in detail. On the base of these models it is established that the set of finite quasigroups is the most acceptable subset of the set of finite magmas at resolving model problems in Cryptography, such as design of iterated hash functions and stream ciphers. Defined families of finite semi-automata and reversible finite automata over finite $T$-quasigroups are investigated in detail. It is established that in this case models time and space complexity for simulation of the functioning during one instant of automaton time can be much lower than in general case.

Helping students learn effective problem solving strategies by reflecting with peers

Science.gov (United States)

Mason, Andrew; Singh, Chandralekha

2010-07-01

We study how introductory physics students engage in reflection with peers about problem solving. The recitations for an introductory physics course with 200 students were broken into a "peer reflection" (PR) group and a traditional group. Each week in recitation, small teams of students in the PR group reflected on selected problems from the homework and discussed why the solutions of some students employed better problem solving strategies than others. The graduate and undergraduate teaching assistants in the PR recitations provided guidance and coaching to help students learn effective problem solving heuristics. In the traditional group recitations students could ask the graduate TA questions about the homework before they took a weekly quiz. The traditional group recitation quiz questions were similar to the homework questions selected for peer reflection in the PR group recitations. As one measure of the impact of this intervention, we investigated how likely students were to draw diagrams to help with problem solving on the final exam with only multiple-choice questions. We found that the PR group drew diagrams on more problems than the traditional group even when there was no explicit reward for doing so. Also, students who drew more diagrams for the multiple-choice questions outperformed those who did not, regardless of which group they were a member.

Domain decomposition methods for mortar finite elements

Energy Technology Data Exchange (ETDEWEB)

Widlund, O.

1996-12-31

In the last few years, domain decomposition methods, previously developed and tested for standard finite element methods and elliptic problems, have been extended and modified to work for mortar and other nonconforming finite element methods. A survey will be given of work carried out jointly with Yves Achdou, Mario Casarin, Maksymilian Dryja and Yvon Maday. Results on the p- and h-p-version finite elements will also be discussed.

Factoring polynomials over arbitrary finite fields

NARCIS (Netherlands)

Lange, T.; Winterhof, A.

2000-01-01

We analyse an extension of Shoup's (Inform. Process. Lett. 33 (1990) 261–267) deterministic algorithm for factoring polynomials over finite prime fields to arbitrary finite fields. In particular, we prove the existence of a deterministic algorithm which completely factors all monic polynomials of

Seismic Shear Energy Reflection By Radon-Fourier Transform

Directory of Open Access Journals (Sweden)

Malik Umairia

2016-01-01

Full Text Available Seismic waves split in an anisotropic medium, instead of rotating horizontal component to principal direction, Radon-Fourier is derived to observe the signature of shear wave reflection. Synthetic model with fracture is built and discretized using finite difference scheme for spatial and time domain. Common depth point (CDP with single shot gives traces and automatic gain is preprocessed before Radon Transform (RT, a filtering technique gives radon domain. It makes easier to observe fractures at specific incidence and improves its quality in some way by removing the noise. A comparison of synthetic data and BF-data is performed on the basis of root means square error (RMS values. The RMS error is minimum at the 10th trace in radon domain.

The finite-difference and finite-element modeling of seismic wave propagation and earthquake motion

International Nuclear Information System (INIS)

Moczo, P.; Kristek, J.; Pazak, P.; Balazovjech, M.; Moczo, P.; Kristek, J.; Galis, M.

2007-01-01

Numerical modeling of seismic wave propagation and earthquake motion is an irreplaceable tool in investigation of the Earth's structure, processes in the Earth, and particularly earthquake phenomena. Among various numerical methods, the finite-difference method is the dominant method in the modeling of earthquake motion. Moreover, it is becoming more important in the seismic exploration and structural modeling. At the same time we are convinced that the best time of the finite-difference method in seismology is in the future. This monograph provides tutorial and detailed introduction to the application of the finite difference (FD), finite-element (FE), and hybrid FD-FE methods to the modeling of seismic wave propagation and earthquake motion. The text does not cover all topics and aspects of the methods. We focus on those to which we have contributed. We present alternative formulations of equation of motion for a smooth elastic continuum. We then develop alternative formulations for a canonical problem with a welded material interface and free surface. We continue with a model of an earthquake source. We complete the general theoretical introduction by a chapter on the constitutive laws for elastic and viscoelastic media, and brief review of strong formulations of the equation of motion. What follows is a block of chapters on the finite-difference and finite-element methods. We develop FD targets for the free surface and welded material interface. We then present various FD schemes for a smooth continuum, free surface, and welded interface. We focus on the staggered-grid and mainly optimally-accurate FD schemes. We also present alternative formulations of the FE method. We include the FD and FE implementations of the traction-at-split-nodes method for simulation of dynamic rupture propagation. The FD modeling is applied to the model of the deep sedimentary Grenoble basin, France. The FD and FE methods are combined in the hybrid FD-FE method. The hybrid

Finite element analysis theory and application with ANSYS

CERN Document Server

Moaveni, Saeed

2015-01-01

For courses in Finite Element Analysis, offered in departments of Mechanical or Civil and Environmental Engineering. While many good textbooks cover the theory of finite element modeling, Finite Element Analysis: Theory and Application with ANSYS is the only text available that incorporates ANSYS as an integral part of its content. Moaveni presents the theory of finite element analysis, explores its application as a design/modeling tool, and explains in detail how to use ANSYS intelligently and effectively. Teaching and Learning Experience This program will provide a better teaching and learning experience-for you and your students. It will help: *Present the Theory of Finite Element Analysis: The presentation of theoretical aspects of finite element analysis is carefully designed not to overwhelm students. *Explain How to Use ANSYS Effectively: ANSYS is incorporated as an integral part of the content throughout the book. *Explore How to Use FEA as a Design/Modeling Tool: Open-ended design problems help stude...

Reflecting Team as an Evaluation/learning Instrument for Self-reflection of Teachers

Directory of Open Access Journals (Sweden)

Michling Malgorzata D.

2017-12-01

Full Text Available The Reflecting Team (RT is a method derived from systemic therapy in the 1980s by the social psychiatrist Tom Andersen. It is increasingly being used in training and evaluation contexts. The aim of the method is to create a space for the development of diverse perspectives and appropriate ideas and solutions in which the integrity of the students/customers/clients is preserved and the acceptance of proposals is facilitated. To this end, the systems involved (advice seekers, consultants, and observers enter a common process of alternately directed and non-directed communication. The RT is not only suitable to address communication problems in group work and other educational situations, but it can also help to consider the traditional teaching and learning processes in a reflective way. Reflecting teams can also significantly improve the feedback and quality of teaching and learning. The article deals with the use of RT in the context of the collective exchange of teaching staff with their students. It uses a problem as an evaluation form and learning instrument to reflect on their pedagogical approach and, at the same time, their relationship with students during the lessons. This is to present the RT method for collegial exchange (Process Flow: Advice-seeker, teacher, Interviewer, RT and their need for teacher reflection as well as the experience of self-efficacy (empowerment and self-sufficiency.

A summary of maintenance policies for a finite interval

International Nuclear Information System (INIS)

Nakagawa, T.; Mizutani, S.

2009-01-01

It would be an important problem to consider practically some maintenance policies for a finite time span, because the working times of most units are finite in actual fields. This paper converts the usual maintenance models to finite maintenance models. It is more difficult to study theoretically optimal policies for a finite time span than those for an infinite time span. Three usual models of periodic replacement with minimal repair, block replacement and simple replacement are transformed to finite replacement models. Further, optimal periodic and sequential policies for an imperfect preventive maintenance and an inspection model for a finite time span are considered. Optimal policies for each model are analytically derived and are numerically computed

Why do probabilistic finite element analysis ?

CERN Document Server

Thacker, Ben H

2008-01-01

The intention of this book is to provide an introduction to performing probabilistic finite element analysis. As a short guideline, the objective is to inform the reader of the use, benefits and issues associated with performing probabilistic finite element analysis without excessive theory or mathematical detail.

Symbolic computation with finite biquandles

OpenAIRE

Creel, Conrad; Nelson, Sam

2007-01-01

A method of computing a basis for the second Yang-Baxter cohomology of a finite biquandle with coefficients in Q and Z_p from a matrix presentation of the finite biquandle is described. We also describe a method for computing the Yang-Baxter cocycle invariants of an oriented knot or link represented as a signed Gauss code. We provide a URL for our Maple implementations of these algorithms.

Finite element application to global reactor analysis

International Nuclear Information System (INIS)

Schmidt, F.A.R.

1981-01-01

The Finite Element Method is described as a Coarse Mesh Method with general basis and trial functions. Various consequences concerning programming and application of Finite Element Methods in reactor physics are drawn. One of the conclusions is that the Finite Element Method is a valuable tool in solving global reactor analysis problems. However, problems which can be described by rectangular boxes still can be solved with special coarse mesh programs more efficiently. (orig.) [de

Uniquely Strongly Clean Group Rings

Institute of Scientific and Technical Information of China (English)

WANG XIU-LAN

2012-01-01

A ring R is called clean if every element is the sum of an idempotent and a unit,and R is called uniquely strongly clean (USC for short) if every element is uniquely the sum of an idempotent and a unit that commute.In this article,some conditions on a ring R and a group G such that RG is clean are given.It is also shown that if G is a locally finite group,then the group ring RG is USC if and only if R is USC,and G is a 2-group.The left uniquely exchange group ring,as a middle ring of the uniquely clean ring and the USC ring,does not possess this property,and so does the uniquely exchange group ring.

Determination of finite-difference weights using scaled binomial windows

KAUST Repository

Chu, Chunlei; Stoffa, Paul L.

2012-01-01

The finite-difference method evaluates a derivative through a weighted summation of function values from neighboring grid nodes. Conventional finite-difference weights can be calculated either from Taylor series expansions or by Lagrange interpolation polynomials. The finite-difference method can be interpreted as a truncated convolutional counterpart of the pseudospectral method in the space domain. For this reason, we also can derive finite-difference operators by truncating the convolution series of the pseudospectral method. Various truncation windows can be employed for this purpose and they result in finite-difference operators with different dispersion properties. We found that there exists two families of scaled binomial windows that can be used to derive conventional finite-difference operators analytically. With a minor change, these scaled binomial windows can also be used to derive optimized finite-difference operators with enhanced dispersion properties. © 2012 Society of Exploration Geophysicists.

Determination of finite-difference weights using scaled binomial windows

KAUST Repository

Chu, Chunlei

2012-05-01

The finite-difference method evaluates a derivative through a weighted summation of function values from neighboring grid nodes. Conventional finite-difference weights can be calculated either from Taylor series expansions or by Lagrange interpolation polynomials. The finite-difference method can be interpreted as a truncated convolutional counterpart of the pseudospectral method in the space domain. For this reason, we also can derive finite-difference operators by truncating the convolution series of the pseudospectral method. Various truncation windows can be employed for this purpose and they result in finite-difference operators with different dispersion properties. We found that there exists two families of scaled binomial windows that can be used to derive conventional finite-difference operators analytically. With a minor change, these scaled binomial windows can also be used to derive optimized finite-difference operators with enhanced dispersion properties. © 2012 Society of Exploration Geophysicists.

Hybrid variational principles and synthesis method for finite element neutron transport calculations

International Nuclear Information System (INIS)

Ackroyd, R.T.; Nanneh, M.M.

1990-01-01

A family of hybrid variational principles is derived using a generalised least squares method. Neutron conservation is automatically satisfied for the hybrid principles employing two trial functions. No interfaces or reflection conditions need to be imposed on the independent even-parity trial function. For some hybrid principles a single trial function can be employed by relating one parity trial function to the other, using one of the parity transport equation in relaxed form. For other hybrid principles the trial functions can be employed sequentially. Synthesis of transport solutions, starting with the diffusion theory approximation, has been used as a way of reducing the scale of the computation that arises with established finite element methods for neutron transport. (author)

Quantitative Estimation of Transmitted and Reflected Lamb Waves at Discontinuity

International Nuclear Information System (INIS)

Lim, Hyung Jin; Sohn, Hoon

2010-01-01

For the application of Lamb wave to structural health monitoring(SHM), understanding its physical characteristic and interaction between Lamb wave and defect of the host structure is an important issue. In this study, reflected, transmitted and mode converted Lamb waves at discontinuity of a plate structure were simulated and the amplitude ratios are calculated theoretically using Modal decomposition method. The predicted results were verified comparing with finite element method(FEM) and experimental results simulating attached PZTs. The result shows that the theoretical prediction is close to the FEM and the experimental verification. Moreover, quantitative estimation method was suggested using amplitude ratio of Lamb wave at discontinuity

Neutron reflectivity studies of confined polymer/polymer interfaces approaching criticality

International Nuclear Information System (INIS)

Sferrazza, M.; Carelli, C.; Jones, R.A.L.; Young, R.N.

2006-01-01

The mechanism by which finite size effects influence the interfacial width between two polymers approaching criticality was investigated. In particular, the relative importance of long-ranged Van der Waals forces and short-ranged 'truncation forces' in modifying the contribution of capillary waves to the interfacial width in thin films was probed with neutron reflectivity. As criticality is approached, a gradual transition is observed from a region where long-ranged dispersion forces are dominant in influencing the capillary wave contribution to the interfacial width, for higher degrees of immiscibility, to a region where short-ranged forces become more important and the dependence of the interfacial width on film thickness is stronger

Exploring the Effects of Disk Thickness on the Black Hole Reflection Spectrum

Science.gov (United States)

Taylor, Corbin; Reynolds, Christopher S.

2018-03-01

The relativistically broadened reflection spectrum, observed in both AGN and X-ray binaries, has proven to be a powerful probe of the properties of black holes and the environments in which they reside. Emitted from the innermost regions of the accretion disk, this X-ray spectral component carries with it information not only about the plasma that resides in these extreme conditions, but also the black hole spin, a marker of the formation and accretion history of these objects. The models currently used to interpret the reflection spectrum are often simplistic, however, approximating the disk as an infinitely thin, optically thick plane of material orbiting in circular Keplerian orbits around the central object. Using a new relativistic ray-tracing suite (Fenrir) that allows for more complex disk approximations, we examine the effects that disk thickness may have on the reflection spectrum. Assuming a lamppost corona, we find that finite disk thickness can have a variety of effects on the reflection spectrum, including a truncation of the blue wing (from self-shadowing of the accretion disk) and an enhancement of the red wing (from the irradiation of the central “eye wall” of the inner disk). We deduce the systematic errors on black hole spin and height that may result from neglecting these effects.

Finite Mixture Multilevel Multidimensional Ordinal IRT Models for Large Scale Cross-Cultural Research

Science.gov (United States)

de Jong, Martijn G.; Steenkamp, Jan-Benedict E. M.

2010-01-01

We present a class of finite mixture multilevel multidimensional ordinal IRT models for large scale cross-cultural research. Our model is proposed for confirmatory research settings. Our prior for item parameters is a mixture distribution to accommodate situations where different groups of countries have different measurement operations, while…

Finite-Element Software for Conceptual Design

DEFF Research Database (Denmark)

Lindemann, J.; Sandberg, G.; Damkilde, Lars

2010-01-01

and research. Forcepad is an effort to provide a conceptual design and teaching tool in a finite-element software package. Forcepad is a two-dimensional finite-element application based on the same conceptual model as image editing applications such as Adobe Photoshop or Microsoft Paint. Instead of using...

Improving Inquiry Teaching through Reflection on Practice

Science.gov (United States)

Lotter, Christine R.; Miller, Cory

2017-08-01

In this paper, we explore middle school science teachers' learning of inquiry-based instructional strategies through reflection on practice teaching sessions during a summer enrichment program with middle level students. The reflection sessions were part of a larger year-long inquiry professional development program in which teachers learned science content and inquiry pedagogy. The program included a 2-week summer institute in which teachers participated in science content sessions, practice teaching to middle level students, and small group-facilitated reflection sessions on their teaching. For this study, data collection focused on teachers' recorded dialogue during the facilitator - run reflection sessions, the teachers' daily written reflections, a final written reflection, and a written reflection on a videotaped teaching session. We investigated the teachers' reflection levels and the themes teachers focused on during their reflection sessions. Teachers were found to reflect at various reflection levels, from simple description to a more sophisticated focus on how to improve student learning. Recurrent themes point to the importance of providing situated learning environments, such as the practice teaching with immediate reflection for teachers to have time to practice new instructional strategies and gain insight from peers and science educators on how to handle student learning issues.

The Gain Estimation of a Fabry-Perot Cavity (FPC Antenna with a Finite Dimension

Directory of Open Access Journals (Sweden)

Taek-Sun Kwon

2017-10-01

Full Text Available In this paper, we have presented an equation for estimating the gain of a Fabry-Perot cavity (FPC antenna with a finite dimension. When an FPC antenna has an infinite dimension and its height is half of a wavelength, the maximum gain of that FPC antenna can be obtained theoretically. If the FPC antenna does not have a dimension sufficient for multiple reflections between a partially reflective surface (PRS and the ground, its gain must be less than that of an FPC antenna that has an infinite dimension. In addition, the gain of an FPC antenna increases as the dimension of a PRS increases and becomes saturated from a specific dimension. The specific dimension where the gain starts to saturate also gets larger as the reflection magnitude of the PRS becomes closer to one. Thus, it would be convenient to have a gain equation when considering the dimension of an FPC antenna in order to estimate the exact gain of the FPC antenna with a specific dimension. A gain versus the dimension of the FPC antenna for various reflection magnitudes of PRS has been simulated, and the modified gain equation is produced through the curve fitting of the full-wave simulation results. The resulting empirical gain equation of an FPC antenna whose PRS dimension is larger than 1.5λ0 has been obtained.

A Dyson-Schwinger approach to finite temperature QCD

Energy Technology Data Exchange (ETDEWEB)

Mueller, Jens Andreas

2011-10-26

The different phases of quantum chromodynamics at finite temperature are studied. To this end the nonperturbative quark propagator in Matsubara formalism is determined from its equation of motion, the Dyson-Schwinger equation. A novel truncation scheme is introduced including the nonperturbative, temperature dependent gluon propagator as extracted from lattice gauge theory. In the first part of the thesis a deconfinement order parameter, the dual condensate, and the critical temperature are determined from the dependence of the quark propagator on the temporal boundary conditions. The chiral transition is investigated by means of the quark condensate as order parameter. In addition differences in the chiral and deconfinement transition between gauge groups SU(2) and SU(3) are explored. In the following the quenched quark propagator is studied with respect to a possible spectral representation at finite temperature. In doing so, the quark propagator turns out to possess different analytic properties below and above the deconfinement transition. This result motivates the consideration of an alternative deconfinement order parameter signaling positivity violations of the spectral function. A criterion for positivity violations of the spectral function based on the curvature of the Schwinger function is derived. Using a variety of ansaetze for the spectral function, the possible quasi-particle spectrum is analyzed, in particular its quark mass and momentum dependence. The results motivate a more direct determination of the spectral function in the framework of Dyson-Schwinger equations. In the two subsequent chapters extensions of the truncation scheme are considered. The influence of dynamical quark degrees of freedom on the chiral and deconfinement transition is investigated. This serves as a first step towards a complete self-consistent consideration of dynamical quarks and the extension to finite chemical potential. The goodness of the truncation is verified first

A Dyson-Schwinger approach to finite temperature QCD

International Nuclear Information System (INIS)

Mueller, Jens Andreas

2011-01-01

The different phases of quantum chromodynamics at finite temperature are studied. To this end the nonperturbative quark propagator in Matsubara formalism is determined from its equation of motion, the Dyson-Schwinger equation. A novel truncation scheme is introduced including the nonperturbative, temperature dependent gluon propagator as extracted from lattice gauge theory. In the first part of the thesis a deconfinement order parameter, the dual condensate, and the critical temperature are determined from the dependence of the quark propagator on the temporal boundary conditions. The chiral transition is investigated by means of the quark condensate as order parameter. In addition differences in the chiral and deconfinement transition between gauge groups SU(2) and SU(3) are explored. In the following the quenched quark propagator is studied with respect to a possible spectral representation at finite temperature. In doing so, the quark propagator turns out to possess different analytic properties below and above the deconfinement transition. This result motivates the consideration of an alternative deconfinement order parameter signaling positivity violations of the spectral function. A criterion for positivity violations of the spectral function based on the curvature of the Schwinger function is derived. Using a variety of ansaetze for the spectral function, the possible quasi-particle spectrum is analyzed, in particular its quark mass and momentum dependence. The results motivate a more direct determination of the spectral function in the framework of Dyson-Schwinger equations. In the two subsequent chapters extensions of the truncation scheme are considered. The influence of dynamical quark degrees of freedom on the chiral and deconfinement transition is investigated. This serves as a first step towards a complete self-consistent consideration of dynamical quarks and the extension to finite chemical potential. The goodness of the truncation is verified first

A modification of projective spacetime by finite self-interaction models of virtual leptons and quarks and the electroweak GWS standard model

International Nuclear Information System (INIS)

Scheurich, H.

1986-01-01

From the projective Dirac equation in a six-dimensional Kleinian space R(3, 3) are derived finite-rotation-group models as self-interaction models of virtual leptons and quarks. The quaternion group underlying them is considered as a substructure group of projective spacetime. A finite hyperspherical carrier of the self-interaction models is embedded into projective spacetime by means of the Planck length L 0 = (hG/c 3 )/sup 1/2/ as a physical unit length. The corresponding modification of metrics in the Planck domain becomes apparent to be equivalent to the role of the Higgs field in the electroweak GWS standard model. (author)

Electron-phonon coupling from finite differences

Science.gov (United States)

Monserrat, Bartomeu

2018-02-01

The interaction between electrons and phonons underlies multiple phenomena in physics, chemistry, and materials science. Examples include superconductivity, electronic transport, and the temperature dependence of optical spectra. A first-principles description of electron-phonon coupling enables the study of the above phenomena with accuracy and material specificity, which can be used to understand experiments and to predict novel effects and functionality. In this topical review, we describe the first-principles calculation of electron-phonon coupling from finite differences. The finite differences approach provides several advantages compared to alternative methods, in particular (i) any underlying electronic structure method can be used, and (ii) terms beyond the lowest order in the electron-phonon interaction can be readily incorporated. But these advantages are associated with a large computational cost that has until recently prevented the widespread adoption of this method. We describe some recent advances, including nondiagonal supercells and thermal lines, that resolve these difficulties, and make the calculation of electron-phonon coupling from finite differences a powerful tool. We review multiple applications of the calculation of electron-phonon coupling from finite differences, including the temperature dependence of optical spectra, superconductivity, charge transport, and the role of defects in semiconductors. These examples illustrate the advantages of finite differences, with cases where semilocal density functional theory is not appropriate for the calculation of electron-phonon coupling and many-body methods such as the GW approximation are required, as well as examples in which higher-order terms in the electron-phonon interaction are essential for an accurate description of the relevant phenomena. We expect that the finite difference approach will play a central role in future studies of the electron-phonon interaction.

Analyzing Reflections in Service Learning to Promote Personal Growth and Community Self-Efficacy

Science.gov (United States)

Sanders, Martha J.; Van Oss, Tracy; McGeary, Signian

2016-01-01

The use of structured reflections for promoting personal understanding and community self-efficacy was examined in 65 occupational therapy college students in a service learning course. Students in the experimental group wrote structured reflections throughout the semester while students in the control groups used non-structured reflections.…

Coxeter groups and the PMNS matrix

Energy Technology Data Exchange (ETDEWEB)

Byakti, Pritibhajan [Indian Association for the Cultivation of Science, Department of Theoretical Physics, Kolkata (India); Pal, Palash B. [Saha Institute of Nuclear Physics, Calcutta (India)

2017-11-15

We discuss symmetries of the Lagrangian of the leptonic sector. We consider the case when this symmetry group is a Coxeter group, and identify the low energy residual symmetries with the involution generators, i.e., generators with order equal to 2. The number of elements of the PMNS matrix predicted by this group structure would depend on the number of generators of this group. We analyze all finite Coxeter groups with two-four generators and check which ones can produce a PMNS matrix that is consistent with experimental data. We then extend the analysis to other groups which can be presented by generators of order 2, and therefore can be seen as subgroups of infinite Coxeter groups. (orig.)

The generalization of the Schur multipliers of Bieberbach groups

Science.gov (United States)

Masri, Rohaidah; Hassim, Hazzirah Izzati Mat; Sarmin, Nor Haniza; Ali, Nor Muhainiah Mohd; Idrus, Nor'ashiqin Mohd

2014-12-01

The Schur multiplier is the second homology group of a group. It has been found to be isomorphic to the kernel of a homomorphism which maps the elements in the exterior square of the group to the elements in its derived subgroup. Meanwhile, a Bieberbach group is a space group which is a discrete cocompact group of isometries of oriented Euclidean space. In this research, the Schur multipliers of Bieberbach groups with cyclic point group of order two of finite dimension are computed.

Optical fiber Bragg gratings. Part II. Modeling of finite-length gratings and grating arrays.

Science.gov (United States)

Passaro, Vittorio M N; Diana, Roberto; Armenise, Mario N

2002-09-01

A model of both uniform finite-length optical fiber Bragg gratings and grating arrays is presented. The model is based on the Floquet-Bloch formalism and allows rigorous investigation of all the physical aspects in either single- or multiple-periodic structures realized on the core of a monomodal fiber. Analytical expressions of reflectivity and transmittivity for both single gratings and grating arrays are derived. The influence of the grating length and the index modulation amplitude on the reflected and transmitted optical power for both sinusoidal and rectangular profiles is evaluated. Good agreement between our method and the well-known coupled-mode theory (CMT) approach has been observed for both single gratings and grating arrays only in the case of weak index perturbation. Significant discrepancies exist there in cases of strong index contrast because of the increasing approximation of the CMT approach. The effects of intragrating phase shift are also shown and discussed.

Reflective journal writing: how it promotes reflective thinking in clinical nursing education: a students' perspective.

Science.gov (United States)

Kok, J; Chabeli, M M

2002-08-01

According to the outcomes-based education and training system of education (OBET) in the country and the South African Nursing Council, education should focus on "creating" reflective learners and practitioners. This article seeks to determine the effectiveness of reflective journal writing in promoting the reflective thinking of learners in clinical nursing education and to validate the guidelines described in a bigger study on how to facilitate reflective thinking using reflective journal writing. A qualitative, contextual, explorative, descriptive research design was used to determine the learners' perceptions on whether reflective journal writing did promote their higher-level thinking skills during the six-month placement in a psychiatric clinical practice using the reflective diaries. From a population of seventeen fourth-year students, six volunteered to participate in a focus group interview. The data was analysed by means of the descriptive method of open coding of Tesch (in Creswell, 1994:154-156). Positive and negative results from the perceptions of the participants and a literature review served as a basis for deducing and describing guidelines for the effective use of reflective journal writing in promoting reflective thinking in clinical nursing education. The positive perception was the development of problem-solving skills attained through reflection by using analytical critical thinking, synthesis and the evaluation of situations. Self-evaluation leading to intellectual growth and self-awareness indicated a positive perception. Negative perceptions were that reflective journal writing is time consuming, content based with a lack of clear expectations from the teacher, and distrust of students about the information written. Guba's model of ensuring trustworthiness in qualitative research as described in Krefting (1991:215-222) was employed. It is concluded that reflective journal writing in clinical nursing education does promote reflective

Incompleteness in the finite domain

Czech Academy of Sciences Publication Activity Database

Pudlák, Pavel

2017-01-01

Roč. 23, č. 4 (2017), s. 405-441 ISSN 1079-8986 EU Projects: European Commission(XE) 339691 - FEALORA Institutional support: RVO:67985840 Keywords : finite domain Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 0.742, year: 2016 https://www.cambridge.org/core/journals/bulletin-of-symbolic-logic/article/incompleteness-in-the-finite-domain/D239B1761A73DCA534A4805A76D81C76

An efficient finite element solution for gear dynamics

International Nuclear Information System (INIS)

Cooley, C G; Parker, R G; Vijayakar, S M

2010-01-01

A finite element formulation for the dynamic response of gear pairs is proposed. Following an established approach in lumped parameter gear dynamic models, the static solution is used as the excitation in a frequency domain solution of the finite element vibration model. The nonlinear finite element/contact mechanics formulation provides accurate calculation of the static solution and average mesh stiffness that are used in the dynamic simulation. The frequency domain finite element calculation of dynamic response compares well with numerically integrated (time domain) finite element dynamic results and previously published experimental results. Simulation time with the proposed formulation is two orders of magnitude lower than numerically integrated dynamic results. This formulation admits system level dynamic gearbox response, which may include multiple gear meshes, flexible shafts, rolling element bearings, housing structures, and other deformable components.

Anti-reflection textured structures by wet etching and island lithography for surface-enhanced Raman spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Chao, Bo-Kai [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Cheng, Hsin-Hung [Department of Marine Engineering, Taipei College of Maritime Technology, Taipei 11174, Taiwan (China); Nien, Li-Wei; Chen, Miin-Jang [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Nagao, Tadaaki [Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Li, Jia-Han [Department of Engineering Science and Ocean Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Hsueh, Chun-Hway, E-mail: hsuehc@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

2015-12-01

Graphical abstract: - Highlights: • We fabricated textured SERS substrate with a high surface area and low reflectance. • Large surface area of substrate contains more gold nanodroplets to absorb analytes. • Low reflectance of textured SERS substrate enabled multiple reflections of incident laser light. • We obtained strong SERS enhancement from nanopillar-on-pyramid SERS substrate. - Abstract: A high surface area and low reflection textured surface-enhanced Raman scattering (SERS) substrate with plasmonic gold nanodroplets fabricated by wet etching and island lithography was reported in the present study. Specifically, four textured substrates, planar, pyramid, nanopillar, and nanopillar-on-pyramid, were fabricated. The fabricated structures were simulated using the finite-difference time-domain method and the results agreed with the reflection and dark-field scattering measurements. Although the SERS signals varied in different measured regions because of the random nanostructure, the SERS substrates with nanopillar-on-pyramid structure always have the stronger enhancement factor than the SERS substrates with only pyramids or nanopillars. Based on the atomic force microscope and reflection measurements, the nanopillar-on-pyramid structure provided a large surface area and multiple reflections for SERS enhancement, which was about 3 orders of magnitude larger than that of the planar substrate. Our results can be applied to fabricate the inexpensive, large surface area, and high SERS enhancement substrates.

An investigation into the impact of reflective teaching on EFL learners autonomy and intrinsic motivation

Directory of Open Access Journals (Sweden)

Elahe Fallah

2015-12-01

Full Text Available This study has sought to explore the effect of reflective teaching on learner autonomy and the intrinsic motivation of Iranian upper-intermediate female learners. The subjects included 60 adult upper-intermediate EFL learners chosen out of ninety, based on the scores obtained through administration of the TOEFL exam. They were randomly assigned to two groups: a the experimental group - taught by a reflective teacher - and b the control group instructed by an unreflective teacher. The motivation questionnaire and the autonomy questionnaire were administered to both groups to make sure that the two groups were not significantly different in terms of the level of motivation and autonomy. The experimental group was then taught by the reflective teacher and the control group was taught by the unreflective teacher who adopted no tangible reflective actions. Finally, both groups sat for motivation and autonomy questionnaires. The results indicate that reflective teaching leads to the enhancement of both learners’ autonomy and the intrinsic motivation level.

Functional renormalization group methods in quantum chromodynamics

International Nuclear Information System (INIS)

Braun, J.

2006-01-01

We apply functional Renormalization Group methods to Quantum Chromodynamics (QCD). First we calculate the mass shift for the pion in a finite volume in the framework of the quark-meson model. In particular, we investigate the importance of quark effects. As in lattice gauge theory, we find that the choice of quark boundary conditions has a noticeable effect on the pion mass shift in small volumes. A comparison of our results to chiral perturbation theory and lattice QCD suggests that lattice QCD has not yet reached volume sizes for which chiral perturbation theory can be applied to extrapolate lattice results for low-energy observables. Phase transitions in QCD at finite temperature and density are currently very actively researched. We study the chiral phase transition at finite temperature with two approaches. First, we compute the phase transition temperature in infinite and in finite volume with the quark-meson model. Though qualitatively correct, our results suggest that the model does not describe the dynamics of QCD near the finite-temperature phase boundary accurately. Second, we study the approach to chiral symmetry breaking in terms of quarks and gluons. We compute the running QCD coupling for all temperatures and scales. We use this result to determine quantitatively the phase boundary in the plane of temperature and number of quark flavors and find good agreement with lattice results. (orig.)

Functional renormalization group methods in quantum chromodynamics

Energy Technology Data Exchange (ETDEWEB)

Braun, J.

2006-12-18

We apply functional Renormalization Group methods to Quantum Chromodynamics (QCD). First we calculate the mass shift for the pion in a finite volume in the framework of the quark-meson model. In particular, we investigate the importance of quark effects. As in lattice gauge theory, we find that the choice of quark boundary conditions has a noticeable effect on the pion mass shift in small volumes. A comparison of our results to chiral perturbation theory and lattice QCD suggests that lattice QCD has not yet reached volume sizes for which chiral perturbation theory can be applied to extrapolate lattice results for low-energy observables. Phase transitions in QCD at finite temperature and density are currently very actively researched. We study the chiral phase transition at finite temperature with two approaches. First, we compute the phase transition temperature in infinite and in finite volume with the quark-meson model. Though qualitatively correct, our results suggest that the model does not describe the dynamics of QCD near the finite-temperature phase boundary accurately. Second, we study the approach to chiral symmetry breaking in terms of quarks and gluons. We compute the running QCD coupling for all temperatures and scales. We use this result to determine quantitatively the phase boundary in the plane of temperature and number of quark flavors and find good agreement with lattice results. (orig.)

Finite size scaling and lattice gauge theory

International Nuclear Information System (INIS)

Berg, B.A.

1986-01-01

Finite size (Fisher) scaling is investigated for four dimensional SU(2) and SU(3) lattice gauge theories without quarks. It allows to disentangle violations of (asymptotic) scaling and finite volume corrections. Mass spectrum, string tension, deconfinement temperature and lattice β-function are considered. For appropriate volumes, Monte Carlo investigations seem to be able to control the finite volume continuum limit. Contact is made with Luescher's small volume expansion and possibly also with the asymptotic large volume behavior. 41 refs., 19 figs

Paracantor: A two group, two region reactor code

Energy Technology Data Exchange (ETDEWEB)

Stone, Stuart

1956-07-01

Paracantor I a two energy group, two region, time independent reactor code, which obtains a closed solution for a critical reactor assembly. The code deals with cylindrical reactors of finite length and with a radial reflector of finite thickness. It is programmed for the 1.B.M: Magnetic Drum Data-Processing Machine, Type 650. The limited memory space available does not permit a flux solution to be included in the basic Paracantor code. A supplementary code, Paracantor 11, has been programmed which computes fluxes, .including adjoint fluxes, from the .output of Paracamtor I.

Renormalization group analysis of the temperature dependent coupling constant in massless theory

International Nuclear Information System (INIS)

Yamada, Hirofumi.

1987-06-01

A general analysis of finite temperature renormalization group equations for massless theories is presented. It is found that in a direction where momenta and temperature are scaled up with their ratio fixed the coupling constant behaves in the same manner as in zero temperature and that asymptotic freedom at short distances is also maintained at finite temperature. (author)

Regularization of finite temperature string theories

International Nuclear Information System (INIS)

Leblanc, Y.; Knecht, M.; Wallet, J.C.

1990-01-01

The tachyonic divergences occurring in the free energy of various string theories at finite temperature are eliminated through the use of regularization schemes and analytic continuations. For closed strings, we obtain finite expressions which, however, develop an imaginary part above the Hagedorn temperature, whereas open string theories are still plagued with dilatonic divergences. (orig.)

'Combined reflectance stratigraphy' - subdivision of loess successions by diffuse reflectance spectrometry (DRS)

Science.gov (United States)

Szeberényi, Jozsef; Bradak-Hayashi, Balázs; Kiss, Klaudia; Kovács, József; Varga, György; Balázs, Réka; Szalai, Zoltán; Viczián, István

2016-04-01

The different varieties of loess (and intercalated paleosol layers) together constitute one of the most widespread terrestrial sediments, which was deposited, altered, and redeposited in the course of the changing climatic conditions of the Pleistocene. To reveal more information about Pleistocene climate cycles and/or environments the detailed lithostratigraphical subdivision and classification of the loess variations and paleosols are necessary. Beside the numerous method such as various field measurements, semi-quantitative tests and laboratory investigations, diffuse reflectance spectroscopy (DRS) is one of the well applied method on loess/paleosol sequences. Generally, DRS has been used to separate the detrital and pedogenic mineral component of the loess sections by the hematite/goethite ratio. DRS also has been applied as a joint method of various environmental magnetic investigations such as magnetic susceptibility- and isothermal remanent magnetization measurements. In our study the so-called "combined reflectance stratigraphy method" were developed. At First, complex mathematical method was applied to compare the results of the spectral reflectance measurements. One of the most preferred multivariate methods is cluster analysis. Its scope is to group and compare the loess variations and paleosol based on the similarity and common properties of their reflectance curves. In the Second, beside the basic subdivision of the profiles by the different reflectance curves of the layers, the most characteristic wavelength section of the reflectance curve was determined. This sections played the most important role during the classification of the different materials of the section. The reflectance value of individual samples, belonged to the characteristic wavelength were depicted in the function of depth and well correlated with other proxies like grain size distribution and magnetic susceptibility data. The results of the correlation showed the significance of