1,346 research outputs found
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Errata report on Herbert Goldstein's Classical Mechanics: Second edition
This report describes errors in Herbert Goldstein's textbook Classical Mechanics, Second Edition (Copyright 1980, ISBN 0-201-02918-9). Some of the errors in current printings of the text were corrected in the second printing; however, after communicating with Addison Wesley, the publisher for Classical Mechanics, it was discovered that the corrected galley proofs had been lost by the printer and that no one had complained of any errors in the eleven years since the second printing. The errata sheet corrects errors from all printings of the second edition
Dual concepts of almost distance-regularity and the spectral excess theorem
Generally speaking, `almost distance-regular' graphs share some, but not
necessarily all, of the regularity properties that characterize
distance-regular graphs. In this paper we propose two new dual concepts of
almost distance-regularity, thus giving a better understanding of the
properties of distance-regular graphs. More precisely, we characterize
-partially distance-regular graphs and -punctually eigenspace
distance-regular graphs by using their spectra. Our results can also be seen as
a generalization of the so-called spectral excess theorem for distance-regular
graphs, and they lead to a dual version of it
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Modularized mirror fusion reactor concept with emphasis on fabricability, assembly, and disassembly
Techniques of futuring: On how imagined futures become socially performative
The concept of the future is re-emerging as an urgent topic on the academic agenda. In this article, we focus on the ‘politics of the future’: the social processes and practices that allow particular imagined futures to become socially performative. Acknowledging that the performativity of such imagined futures is well-understood, we argue that how particular visions come about and why they become performative is underexplained. Drawing on constructivist sociological theory, this article aims to fill (part of) this gap by exploring the question ‘how do imagined futures become socially performative’? In doing so, the article has three aims to (1) identify the leading social–theoretical work on the future; (2) conceptualize the relationship of the imagination of the future with social practices and the performance of reality; (3) provide a theoretical framework explaining how images of the future become performative, using the concepts ‘techniques of futuring’ and ‘dramaturgical regime’
On almost distance-regular graphs
Distance-regular graphs are a key concept in Algebraic Combinatorics and have
given rise to several generalizations, such as association schemes. Motivated
by spectral and other algebraic characterizations of distance-regular graphs,
we study `almost distance-regular graphs'. We use this name informally for
graphs that share some regularity properties that are related to distance in
the graph. For example, a known characterization of a distance-regular graph is
the invariance of the number of walks of given length between vertices at a
given distance, while a graph is called walk-regular if the number of closed
walks of given length rooted at any given vertex is a constant. One of the
concepts studied here is a generalization of both distance-regularity and
walk-regularity called -walk-regularity. Another studied concept is that of
-partial distance-regularity or, informally, distance-regularity up to
distance . Using eigenvalues of graphs and the predistance polynomials, we
discuss and relate these and other concepts of almost distance-regularity, such
as their common generalization of -walk-regularity. We introduce the
concepts of punctual distance-regularity and punctual walk-regularity as a
fundament upon which almost distance-regular graphs are built. We provide
examples that are mostly taken from the Foster census, a collection of
symmetric cubic graphs. Two problems are posed that are related to the question
of when almost distance-regular becomes whole distance-regular. We also give
several characterizations of punctually distance-regular graphs that are
generalizations of the spectral excess theorem
Intelligent planning for allocating containers in maritime terminals
Maritime container terminals are facilities where cargo containers are transshipped between ships or between ships and land vehicles (tucks or trains). These terminals involve a large number of complex and combinatorial problems. One of them is related to the Container Stacking Problem. A container yard is a type of temporary store where containers await further transport by truck, train or vessel. The main efficiency problem for an individual stack is to ensure easy access to containers at the expected time of transfer. Stacks are 'last-in, first-out' storage structures where containers are stocked in the order they arrive. But they should be retrieved from the stack in the order (usually different) they should be shipped. This retrieval operation should be efficiently performed, since berthing time of vessels and the terminal operations should be optimized. To do this, cranes can relocate containers in the stacks to minimize the rearrangements required to meet the expected order of demand for containers. In this paper, we present a domain-dependent heuristically guided planner for obtaining the optimized reshuffling plan, given a stacking state and a container demand. The planner can also be used for finding the best allocation of containers in a yard-bay in order to minimize the number of reshuffles as well as to be used for simulation tasks and obtaining conclusions about possible yard configurations. © 2011 Elsevier Ltd. All rights reserved.This work has been partially supported by the research projects TIN2010-20976-C02-01 (Min. de Ciencia e Innovacion, Spain), P19/08 (Min. de Fomento, Spain-FEDER) and the VALi+d Program of the Conselleria d'Educacio (Generalitat Valenciana), as well as with the collaboration of the maritime container terminal MSC (Mediterranean Shipping Company S.A.).Rodríguez Molins, M.; Salido Gregorio, MA.; Barber Sanchís, F. (2012). Intelligent planning for allocating containers in maritime terminals. Expert Systems with Applications. 39(1):978-989. https://doi.org/10.1016/j.eswa.2011.07.098S97898939
Improving Strategies via SMT Solving
We consider the problem of computing numerical invariants of programs by
abstract interpretation. Our method eschews two traditional sources of
imprecision: (i) the use of widening operators for enforcing convergence within
a finite number of iterations (ii) the use of merge operations (often, convex
hulls) at the merge points of the control flow graph. It instead computes the
least inductive invariant expressible in the domain at a restricted set of
program points, and analyzes the rest of the code en bloc. We emphasize that we
compute this inductive invariant precisely. For that we extend the strategy
improvement algorithm of [Gawlitza and Seidl, 2007]. If we applied their method
directly, we would have to solve an exponentially sized system of abstract
semantic equations, resulting in memory exhaustion. Instead, we keep the system
implicit and discover strategy improvements using SAT modulo real linear
arithmetic (SMT). For evaluating strategies we use linear programming. Our
algorithm has low polynomial space complexity and performs for contrived
examples in the worst case exponentially many strategy improvement steps; this
is unsurprising, since we show that the associated abstract reachability
problem is Pi-p-2-complete
The Generalized Liquid Drop Model Alpha-Decay Formula: Predictability Analysis and Super-Heavy Element Alpha Half-Lives
The predictive accuracy of the generalized liquid drop model (GLDM) formula
for alpha decay half-lives has been investigated in a detailed manner and a
variant of the formula with improved coefficients is proposed. The method
employs the experimental alpha half-lives of the well-known alpha standards
(REFERENCE) to obtain the coefficients of the analytical formula using the
experimental Qalpha values (the DSR-E formula), as well as the finite range
droplet model (FRDM) derived Qalpha values (the FRDMFRDM formula). The
predictive accuracy of these formulae were checked against the experimental
alpha half-lives of an independent set of nuclei (TEST) that span approximately
the same Z,A region as the standards and possess reliable alpha spectroscopic
data, and were found to yield good results for the DSR-E formula but not for
the FRDM-FRDM formula. The two formulae were used to obtain the alpha
half-lives of super-heavy (SHE) and heavy nuclides where the relative accuracy
was found to markedly improve for the FRDM-FRDM, which corroborates the
appropriateness of the FRDM masses and the GLDM prescription for high Z,A
nuclides. Further improvement resulted, especially for the FRDM-FRDM formula,
after a simple linear optimization over the calculated and experimental
half-lives of TEST was used to re-calculate the half-lives of the SHE and heavy
nuclides. The advantage of this optimization was that it required no
recalculation of the coefficients of the basic DSR-E or FRDM-FRDM formulae. The
halflives for 324 medium-mass to super-heavy alpha decaying nuclides,
calculated using these formulae and the comparison with experimental
half-lives, are presented.Comment: 61 pages, 6 figures, PDF file, to appear in Atomic Data and Nuclear
Data Table
Constructions of free commutative integro-differential algebras
In this survey, we outline two recent constructions of free commutative
integro-differential algebras. They are based on the construction of free
commutative Rota-Baxter algebras by mixable shuffles. The first is by
evaluations. The second is by the method of Gr\"obner-Shirshov bases.Comment: arXiv admin note: substantial text overlap with arXiv:1302.004
The Paradox of Muscle Hypertrophy in Muscular Dystrophy
Mutations in the dystrophin gene cause Duchenne and Becker muscular dystrophy in humans and syndromes in mice, dogs, and cats. Affected humans and dogs have progressive disease that leads primarily to muscle atrophy. Mdx mice progress through an initial phase of muscle hypertrophy followed by atrophy. Cats have persistent muscle hypertrophy. Hypertrophy in humans has been attributed to deposition of fat and connective tissue (pseudohypertrophy). Increased muscle mass (true hypertrophy) has been documented in animal models. Muscle hypertrophy can exaggerate postural instability and joint contractures. Deleterious consequences of muscle hypertrophy should be considered when developing treatments for muscular dystrophy
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