1,920 research outputs found

    A Study of the Problems of Cost Analysis in the Petroleum Industry

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    The significance of the subject of the present study-the cost of finding, developing and producing petroleum-can be better understood by placing it against a summary view of the supply situation in the postwar world. The most striking fact is the appearance of vast new reserves of oil in various parts of the world. Earlier concern over conservation was aroused by the fear of depletion of the available supply. Taking a long view, this possibility is not to be dismissed. But in recent years the practical problems of the industry, and of public policy toward it, are of a different sort. The capacity of the industry to produce in the countries of the free world greatly exceeds the current rates of consumption. From the sellers\u27 point of view, at least, it seems self-evident that too much oil exists today

    Theoretical Aspects of the Equivalence Principle

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    We review several theoretical aspects of the Equivalence Principle (EP). We emphasize the unsatisfactory fact that the EP maintains the absolute character of the coupling constants of physics while General Relativity, and its generalizations (Kaluza-Klein,..., String Theory), suggest that all absolute structures should be replaced by dynamical entities. We discuss the EP-violation phenomenology of dilaton-like models, which is likely to be dominated by the linear superposition of two effects: a signal proportional to the nuclear Coulomb energy, related to the variation of the fine-structure constant, and a signal proportional to the surface nuclear binding energy, related to the variation of the light quark masses. We recall the various theoretical arguments (including a recently proposed anthropic argument) suggesting that the EP be violated at a small, but not unmeasurably small level. This motivates the need for improved tests of the EP. These tests are probing new territories in physics that are related to deep, and mysterious, issues in fundamental physics.Comment: 21 pages, no figures; submitted to a "focus issue" of Classical and Quantum Gravity on Tests of the Weak Equivalence Principle, organized by Clive Speake and Clifford Wil

    Correspondence from E.B. Lovejoy, August 11, 1862

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    Correspondence from E.B. Lovejoy regarding absent soldiers from Androscoggin Countyhttps://digitalmaine.com/absent_soldiers/1008/thumbnail.jp

    Jensen-Shannon Complexity and Permutation Entropy Analysis of Geomagnetic Auroral Currents

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    In this study we determine whether auroral westward currents can be characterized by low-dimensional chaotic attractors through the use of the complexity-entropy methodology developed by Rosso et al. (2007, https:// doi.org/10.1103/PhysRevLett.99.154102) and based on the permutation entropy developed by Bandt and Pompe (2002, https://doi.org/10.1103/PhysRevLett.88.174102) . Our results indicate that geomagnetic auroral indices are indistinguishable from stochastic processes from time scales ranging from a few minutes to 10 hr and for embedded dimensions d <8. Our results are inconsistent with earlier studies of Baker et al. (1990, https://doi.org/10.1029/GL017i001p00041), Pavlos et al. (1992), D. Roberts et al. (1991, https://doi.org/10.1029/91GL00021), D. A. Roberts (1991, https://doLorg/10.1029/91JA01088), and Vassiliadis et al. (1990, https://doi.org/10.1029/GL017i011 p01841, 1991, https://doi.org/10.1029/91GL01378) indicating that auroral geomagnetic indices could be reduced to low-dimensional systems with chaotic dynamics.Peer reviewe

    Shape complexity and fractality of fracture surfaces of swelled isotactic polypropylene with supercritical carbon dioxide

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    We have investigated the fractal characteristics and shape complexity of the fracture surfaces of swelled isotactic polypropylene Y1600 in supercritical carbon dioxide fluid through the consideration of the statistics of the islands in binary SEM images. The distributions of area AA, perimeter LL, and shape complexity CC follow power laws p(A)∼A−(μA+1)p(A)\sim A^{-(\mu_A+1)}, p(L)∼L−(μL+1)p(L)\sim L^{-(\mu_L+1)}, and p(C)∼C−(ν+1)p(C)\sim C^{-(\nu+1)}, with the scaling ranges spanning over two decades. The perimeter and shape complexity scale respectively as L∼AD/2L\sim A^{D/2} and C∼AqC\sim A^q in two scaling regions delimited by A≈103A\approx 10^3. The fractal dimension and shape complexity increase when the temperature decreases. In addition, the relationships among different power-law scaling exponents μA\mu_A, μB\mu_B, ν\nu, DD, and qq have been derived analytically, assuming that AA, LL, and CC follow power-law distributions.Comment: RevTex, 6 pages including 7 eps figure

    On the dual nature of partial theta functions and Appell-Lerch sums

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    In recent work, Hickerson and the author demonstrated that it is useful to think of Appell--Lerch sums as partial theta functions. This notion can be used to relate identities involving partial theta functions with identities involving Appell--Lerch sums. In this sense, Appell--Lerch sums and partial theta functions appear to be dual to each other. This duality theory is not unlike that found by Andrews between various sets of identities of Rogers-Ramanujan type with respect to Baxter's solution to the hard hexagon model of statistical mechanics. As an application we construct bilateral qq-series with mixed mock modular behaviour.Comment: To be published in Advances in Mathematic

    The Equivalence Principle and the Constants of Nature

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    We briefly review the various contexts within which one might address the issue of ``why'' the dimensionless constants of Nature have the particular values that they are observed to have. Both the general historical trend, in physics, of replacing a-priori-given, absolute structures by dynamical entities, and anthropic considerations, suggest that coupling ``constants'' have a dynamical nature. This hints at the existence of observable violations of the Equivalence Principle at some level, and motivates the need for improved tests of the Equivalence Principle.Comment: 12 pages; invited talk at the ISSI Workshop on the Nature of Gravity: Confronting Theory and Experiment in Space, Bern, Switzerland, 6-10 October 2008; to appear in Space Science Review

    Nonlinear Analysis and Preliminary Testing Results of a Hybrid Wing Body Center Section Test Article

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    A large test article was recently designed, analyzed, fabricated, and successfully tested up to the representative design ultimate loads to demonstrate that stiffened composite panels with through-the-thickness reinforcement are a viable option for the next generation large transport category aircraft, including non-conventional configurations such as the hybrid wing body. This paper focuses on finite element analysis and test data correlation of the hybrid wing body center section test article under mechanical, pressure and combined load conditions. Good agreement between predictive nonlinear finite element analysis and test data is found. Results indicate that a geometrically nonlinear analysis is needed to accurately capture the behavior of the non-circular pressurized and highly-stressed structure when the design approach permits local buckling

    Testing and Analysis of a Composite Non-Cylindrical Aircraft Fuselage Structure

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    The Environmentally Responsible Aviation Project aimed to develop aircraft technologies enabling significant fuel burn and community noise reductions. Small incremental changes to the conventional metallic alloy-based 'tube and wing' configuration were not sufficient to achieve the desired metrics. One airframe concept identified by the project as having the potential to dramatically improve aircraft performance was a composite-based hybrid wing body configuration. Such a concept, however, presented inherent challenges stemming from, among other factors, the necessity to transfer wing loads through the entire center fuselage section which accommodates a pressurized cabin confined by flat or nearly flat panels. This paper discusses a finite element analysis and the testing of a large-scale hybrid wing body center section structure developed and constructed to demonstrate that the Pultruded Rod Stitched Efficient Unitized Structure concept can meet these challenging demands of the next generation airframes. Part II of the paper considers the final test to failure of the test article in the presence of an intentionally inflicted severe discrete source damage under the wing up-bending loading condition. Finite element analysis results are compared with measurements acquired during the test and demonstrate that the hybrid wing body test article was able to redistribute and support the required design loads in a severely damaged condition
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