437 research outputs found

    Прогнозирование и вероятностная оценка долговечности технических объектов

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    На основе методологии марковского анализа надежности предложен вероятностный подход к прогнозированию и оценке долговечности технических объектов. Разработана математическая модель прогнозирования долговечности с использованием статистических данных, характеризующих начальное и конечное распределение продолжительности срока службы технических объектов.На основі методології марківського аналізу надійності запропоновано ймовірнісний підхід до прогнозування та оцінки довговічності технічних об’єктів. Розроблено математичну модель прогнозування довговічності з використанням статистичних даних, що характеризують початковий та кінцевий розподіл тривалості терміну служби технічних об’єктів.Based on the methodology of the Markov analysis, a probabilistic approach to forecast and estimation of the longevity of technical objects is offered. A mathematical model of the longevity forecast is developed with the use of statistical data characterizing the initial and final distribution of the service term of technical objects

    A quantitative comparison of dispersed spore/pollen and plant megafossil assemblages from a Middle Jurassic plant bed from Yorkshire, UK

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    Detailed quantitative data has previously been collected from plant megafossil assemblages from a Middle Jurassic (Aalenian) plant bed from Hasty Bank, North Yorkshire, UK. We conducted a similar analysis of palynological dispersed sporomorph (spore and pollen) assemblages collected from the same section using the same sampling regime: 67 sporomorph taxa were recorded from 50 samples taken at 10 cm intervals through the plant bed. Basic palynofacies analysis was also undertaken on each sample. Both dispersed sporomorph and plant megafossil assemblages display consistent changes in composition, diversity (richness), and abundance through time. However, the dispersed sporomorph and plant megafossil records provide conflicting evidence for the nature of parent vegetation. Specifically, conifers and ferns are underrepresented in plant megafossil assemblages, bryophytes and lycopsids are represented only in sporomorph assemblages, and sphenophytes, pteridosperms, Caytoniales, Cycadales, Ginkgoales and Bennettitales are comparatively underrepresented in sporomorph assemblages. Combined multivariate analysis (correspondence analysis and nonmetric multidimensional scaling) of sporomorph occurrence/abundance data demonstrates that temporal variation in sporomorph assemblages is the result of depositional change through the plant bed. The reproductive strategies of parent plants are considered to be a principal factor in shaping many of the major abundance and diversity irregularities between dispersed sporomorph and plant megafossil data sets that seemingly reflects different parent vegetation. Preferential occurrence/preservation of sporomorphs and equivalent parent plants is a consequence of a complex array of biological, ecological, geographical, taphonomic, and depositional factors that act inconsistently between and within fossil assemblages, which results in notable discrepancies between data sets

    Банда і злочинна організація: проблема співвідношення понять

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    Розкривається проблема співвідношення понять «банда» та «злочинна організація». На основі критичного аналізу існуючих наукових підходів до визначення сутнісних ознак понять «банда» та «злочинна організація» та судової практики розгляду кримінальних справ про злочини, вчинені такими злочинними об’єднаннями, автором пропонуються конкретні підходи до їх співвідношення.Раскрывается проблема соотношения понятий «банда» и «преступная организация». На основе критического анализа существующих научных подходов на определение сущностных признаков понятий «банда» и «преступная организация» и судебной практики рассмотрения уголовных дел о преступлениях, совершенных такими преступными объединениями автором предлагаются конкретные подходы к их соотношению.Opens up the problem of correlation of the concepts «band» and «criminal organization». Founded on critical analysis of the existing scientific approaches at definition of the essence signs of the concepts «band» and «criminal organization» and judicial practice of consideration criminal cases about crimes are committed by that criminal associations author offers certain approaches at their correlation

    Fossiele planten: voer voor Dino’s?

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    Light incoherence due to quantum-gravitational fluctuations of the background space

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    Based on the theory of mutual coherence of light from an extended incoherent quasi-monochromatic source (providing a basis of stellar interferometry) we estimate the degree of light incoherence due to quantum-gravitational fluctuations of the background metric. It is shown that the stellar interferometry observational data considered in the literature for a last few years as a manifestation against the Planck scale quantum-gravitational fluctuations of the background metric have no chance for detecting such an effect.Comment: 5 pages; Version to appear in Astroparticle Physic

    Optimal Concentration of Light in Turbid Materials

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    In turbid materials it is impossible to concentrate light into a focus with conventional optics. Recently it has been shown that the intensity on a dyed probe inside a turbid material can be enhanced by spatially shaping the wave front of light before it enters a turbid medium. Here we show that this enhancement is due to concentration of light energy to a spot much smaller than a wavelength. We focus light on a dyed probe sphere that is hidden under an opaque layer. The light is optimally concentrated to a focus which does not exceed the smallest focal area physically possible by more than 68%. A comparison between the intensity enhancements of both the emission and excitation light supports the conclusion of optimal light concentration.Comment: We corrected an ambiguous description of the focus size in our abstract and text pointed out by an anonymous refere

    Experimental verification of the Heisenberg uncertainty principle for hot fullerene molecules

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    The Heisenberg uncertainty principle for material objects is an essential corner stone of quantum mechanics and clearly visualizes the wave nature of matter. Here we report a demonstration of the Heisenberg uncertainty principle for the most massive, complex and hottest single object so far, the fullerene molecule C70 at a temperature of 900 K. We find a good quantitative agreement with the theoretical expectation: dx * dp = h, where dx is the width of the restricting slit, dp is the momentum transfer required to deflect the fullerene to the first interference minimum and h is Planck's quantum of action.Comment: 4 pages, 4 figure

    Space-Time Approach to Scattering from Many Body Systems

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    We present scattering from many body systems in a new light. In place of the usual van Hove treatment, (applicable to a wide range of scattering processes using both photons and massive particles) based on plane waves, we calculate the scattering amplitude as a space-time integral over the scattering sample for an incident wave characterized by its correlation function which results from the shaping of the wave field by the apparatus. Instrument resolution effects - seen as due to the loss of correlation caused by the path differences in the different arms of the instrument are automatically included and analytic forms of the resolution function for different instruments are obtained. The intersection of the moving correlation volumes (those regions where the correlation functions are significant) associated with the different elements of the apparatus determines the maximum correlation lengths (times) that can be observed in a sample, and hence, the momentum (energy) resolution of the measurement. This geometrical picture of moving correlation volumes derived by our technique shows how the interaction of the scatterer with the wave field shaped by the apparatus proceeds in space and time. Matching of the correlation volumes so as to maximize the intersection region yields a transparent, graphical method of instrument design. PACS: 03.65.Nk, 3.80 +r, 03.75, 61.12.BComment: Latex document with 6 fig

    Burmese amber fossils bridge the gap in the Cretaceous record of polypod ferns

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    publisher: Elsevier articletitle: Burmese amber fossils bridge the gap in the Cretaceous record of polypod ferns journaltitle: Perspectives in Plant Ecology, Evolution and Systematics articlelink: http://dx.doi.org/10.1016/j.ppees.2016.01.003 content_type: article copyright: Copyright © 2016 Elsevier GmbH. All rights reserved.Copyright © 2016 Elsevier GmbH. All rights reserved. This document is the authors' final accepted version of the journal article. You are advised to consult the publisher's version if you wish to cite from it
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