15,243 research outputs found

    Elements of Design for Containers and Solutions in the LinBox Library

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    We describe in this paper new design techniques used in the \cpp exact linear algebra library \linbox, intended to make the library safer and easier to use, while keeping it generic and efficient. First, we review the new simplified structure for containers, based on our \emph{founding scope allocation} model. We explain design choices and their impact on coding: unification of our matrix classes, clearer model for matrices and submatrices, \etc Then we present a variation of the \emph{strategy} design pattern that is comprised of a controller--plugin system: the controller (solution) chooses among plug-ins (algorithms) that always call back the controllers for subtasks. We give examples using the solution \mul. Finally we present a benchmark architecture that serves two purposes: Providing the user with easier ways to produce graphs; Creating a framework for automatically tuning the library and supporting regression testing.Comment: 8 pages, 4th International Congress on Mathematical Software, Seoul : Korea, Republic Of (2014

    Darwin-Lagrangian Analysis for the Interaction of a Point Charge and a Magnet: Considerations Related to the Controversy Regarding the Aharonov-Bohm and Aharonov-Casher Phase Shifts

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    The classical electromagnetic interaction of a point charge and a magnet is discussed by first calculating the interaction of point charge with a simple model magnetic moment and then suggesting a multiparticle limit. The Darwin Lagrangian is used to analyze the electromagnetic behavior of the model magnetic moment (composed of two oppositely charged particles of different mass in an initially circular orbit) interacting with a passing point charge. The changing mangetic moment is found to put a force back on a passing charge; this force is of order 1/c^2 and depends upon the magnitude of the magnetic moment. It is suggested that in the limit of a multiparticle magnetic toroid, the electric fields of the passing charge are screened out of the body of the magnet while the magnetic fields penetrate into the magnet. This is consistent with our understanding of the penetration of electromagnetic velocity fields into ohmic conductors. Conservation laws are discussed. The work corresponds to a classical electromagnetic analysis of the interaction which is basic to understanding the controversy over the Aharonov-Bohm and Aharonov-Casher phase shifts and represents a refutation of the suggestions of Aharonov, Pearle, and Vaidman.Comment: 33 page

    The Paradoxical Forces for the Classical Electromagnetic Lag Associated with the Aharonov-Bohm Phase Shift

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    The classical electromagnetic lag assocated with the Aharonov-Bohm phase shift is obtained by using a Darwin-Lagrangian analysis similar to that given by Coleman and Van Vleck to identify the puzzling forces of the Shockley-James paradox. The classical forces cause changes in particle velocities and so produce a relative lag leading to the same phase shift as predicted by Aharonov and Bohm and observed in experiments. An experiment is proposed to test for this lag aspect implied by the classical analysis but not present in the currently-accepted quantum topological description of the phase shift.Comment: 8 pages, 3 figure

    Derivation of the Blackbody Radiation Spectrum from a Natural Maximum-Entropy Principle Involving Casimir Energies and Zero-Point Radiation

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    By numerical calculation, the Planck spectrum with zero-point radiation is shown to satisfy a natural maximum-entropy principle whereas alternative choices of spectra do not. Specifically, if we consider a set of conducting-walled boxes, each with a partition placed at a different location in the box, so that across the collection of boxes the partitions are uniformly spaced across the volume, then the Planck spectrum correspond to that spectrum of random radiation (having constant energy kT per normal mode at low frequencies and zero-point energy (1/2)hw per normal mode at high frequencies) which gives maximum uniformity across the collection of boxes for the radiation energy per box. The analysis involves Casimir energies and zero-point radiation which do not usually appear in thermodynamic analyses. For simplicity, the analysis is presented for waves in one space dimension.Comment: 11 page

    The Law of the Minimum and Sources of Nonzero Skewness for Crop Yield Distributions

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    Crop yields are not commonly found to be normally distributed, but the cause of the non-normal distribution is unclear. The non-normality might be due to weather variables and/or an underlying von Liebig law of the minimum (LoM) production function. Our objective is to determine the degree to which an underlying linear response stochastic plateau production function can explain the skewness of Oklahoma wheat yields at varied nitrogen rates. We use farm-level wheat data from a long-term experiment in Oklahoma, which is a unique data set to the literature. The Tembo et al. (2008) production function provides negative skewness at all levels of nitrogen with skewness near zero for both very high and very low levels of nitrogen. Observed skewness for wheat yields, however, is positive. The variation in the plateau by year shows positive skewness. Skewness in yield potential related to weather should be considered as a possible explanation of skewness.linear plateau model, non-normal distributions, skewness, wheat, yield distribution, Production Economics, Risk and Uncertainty, Q10,

    Some Heuristic Semiclassical Derivations of the Planck Length, the Hawking Effect and the Unruh Effect

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    The formulae for Planck length, Hawking temperature and Unruh-Davies temperature are derived by using only laws of classical physics together with the Heisenberg principle. Besides, it is shown how the Hawking relation can be deduced from the Unruh relation by means of the principle of equivalence; the deep link between Hawking effect and Unruh effect is in this way clarified.Comment: LaTex file, 6 pages, no figure

    Hydrodynamic reductions of the heavenly equation

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    We demonstrate that Pleba\'nski's first heavenly equation decouples in infinitely many ways into a triple of commuting (1+1)-dimensional systems of hydrodynamic type which satisfy the Egorov property. Solving these systems by the generalized hodograph method, one can construct exact solutions of the heavenly equation parametrized by arbitrary functions of a single variable. We discuss explicit examples of hydrodynamic reductions associated with the equations of one-dimensional nonlinear elasticity, linearly degenerate systems and the equations of associativity.Comment: 14 page

    Alternatives to Administrative Trial-Type Hearings for Resolving Complex Scientific, Economic, and Social Issues

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    Within the current wave of criticism directed at the federal administrative agencies, a traditional theme of administrative law is frequently echoed: agencies have allowed their proceedings to become over-judicialized, and ought to engage in more rule-making to avoid the slow, cumbersome, and repetitious process of case-by- case adjudication. As if to confirm the urgency of these calls for greater use of the rule-making power, examples occasionally surface which suggest that trial-type proceedings may collapse under their own weight and force some agencies to resort to rule-making if they are to accomplish anything at all. Thus, the Interstate Commerce Commission has announced that a massive rail-merger case has become so unmanageable that the hearing examiner\u27s initial decision must be issued in multiple volumes, and an experienced commentator has concluded that the Atomic Energy Commission\u27s duty to consider the environmental impact of nuclear reactors in trial-type hearings places AEC licensing boards in an impossible position and may well prove undoable. At the same time, however, those who may be adversely affected by agency rule-making action often prefer what they conceive to be the greater procedural safeguards of trial-type hearings, and usually can find support in Congress; indeed, a recent study concluded that, with very few exceptions, the major grants of rule-making authority made by Congress within the past decade have contained procedural requirements that go beyond the notice-and-comment practice prescribed for informal rule-making by the Administrative Procedure Act (AP A). Perhaps in recognition of these practical pressures, some commentators have urged that the distinction between adjudication and rule-making can impede analysis and that it may be useful in some areas to acknowledge hybrid forms of procedure incorporating various elements of both adjudication and rule-making, and other procedural techniques as well. Similarly, some of the current literature on environmental law contains references to generic and ad hoc or particularized proceedings, terms which seem designed to avoid the procedural implications of labeling a certain form of agency activity as either adjudication or rule-making. Since the problems and uncertainties surrounding the administrative uses of trial-type proceedings seem substantial, it may be helpful to take a fresh look at both the kinds of issues that seem to be causing the most difficulties in the administrative process and the attributes of the trial-type hearing in comparison to other forms of decision-making
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