8,710 research outputs found

    Modelling of Metal-Coating Delamination Incorporating Variable Environmental Parameters

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    A mathematical model for metal-coat delamination of degrading metal was developed incorporating multiple variable environmental parameters. Metal-coat delamination not only depends on the electrochemical reactions at metal-coat interface but also on the factors like the type of propagating metal ions and their varying concentration with annual weather changes, time of exposure of the coated objects, type of coated objects are stationary or mobile vehicles, frequency with which certain vehicles are operating in various environments e.g. controlled or uncontrolled in terms of environmental conditions. A cutting edge model has been developed to calculate the varying environmental conditions using iteration algorithm, time dependent uncertain position of objects like vehicle in various environments using stochastic approach, effect of seasonal changes on ionic compound's concentration using algebraic method and instantaneous failure probability due to varying conditions. Based on the developed model a detailed simulation study was conducted to investigate the metal-coat delamination process and the ways to regress the under coat metal corrosion

    User's manual for COPTRAN, a method of optimum communication system design

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    User manual for COPTRAN /communication system optimization program translator

    COPTRAN - A method of optimum communication systems design

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    Single set of mathematical expressions describes system cost and probability of error of data transmission in terms of four basic parameters in the link equation. A Lagrange multiplier sets up equations whose solutions yield the optimum values for system design considerations and weight and cost values

    Study and development of a mathematical analysis for the performance assessment of space communication system parameters

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    Electronic computer program user manual for optimum design of space communication syste

    Thin-film flow in helically wound rectangular channels with small torsion

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    Laminar gravity-driven thin-film flow down a helically-wound channel of rectangular cross-section with small torsion in which the fluid depth is small is considered. Neglecting the entrance and exit regions we obtain the steady-state solution that is independent of position along the axis of the channel, so that the flow, which comprises a primary flow in the direction of the axis of the channel and a secondary flow in the cross-sectional plane, depends only on position in the two-dimensional cross-section of the channel. A thin-film approximation yields explicit expressions for the fluid velocity and pressure in terms of the free-surface shape, the latter satisfying a non-linear ordinary differential equation that has a simple exact solution in the special case of a channel of rectangular cross-section. The predictions of the thin-film model are shown to be in good agreement with much more computationally intensive solutions of the small-helix-torsion Navier–Stokes equations. The present work has particular relevance to spiral particle separators used in the mineral-processing industry. The validity of an assumption commonly used in modelling flow in spiral separators, namely that the flow in the outer region of the separator cross-section is described by a free vortex, is shown to depend on the problem parameters

    Parametric analysis of microwave and laser systems for communication and tracking. Volume 2 - System selection

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    System selection criteria of microwave and laser systems for communication and tracking - Vol.

    Fauna and flora of the Great Barrier Reef World Heritage Area : a compendium of information and basis for the species conservation program in the Great Barrier Reef Marine Park Authority: first edition

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    The way in which GBRMPA manages for the conservation of species in the Great Barrier Reef World Heritage Area (GBRWHA) is determined mainly by legislative instrument and policy decisions. This Report has been prepared to explain the rationale behind the work priorities of the Species Conservation Program of GBRMPA. The Report will be reviewed and updated as additional information becomes available and in the light of changes to work priorities and budgets

    Complex trajectory method in time-dependent WKB

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    We present a significant improvement to a time-dependent WKB (TDWKB) formulation developed by Boiron and Lombardi [JCP {\bf108}, 3431 (1998)] in which the TDWKB equations are solved along classical trajectories that propagate in the complex plane. Boiron and Lombardi showed that the method gives very good agreement with the exact quantum mechanical result as long as the wavefunction does not exhibit interference effects such as oscillations and nodes. In this paper we show that this limitation can be overcome by superposing the contributions of crossing trajectories. We also demonstrate that the approximation improves when incorporating higher order terms in the expansion. These improvements could make the TDWKB formulation a competitive alternative to current time-dependent semiclassical methods

    Extending the aridity record of the Southwest Kalahari: current problems and future perspectives

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    An extensive luminescence-based chronological framework has allowed the reconstruction of expansions and contractions of the Kalahari Desert over the last 50 ka. However, this chronology is largely based on near-surface pits and sediment exposures. These are the points on the landscape most prone to reactivation and resetting of the luminescence dating ‘clock’. This is proving to be a limiting feature for extending palaeoenvironmental reconstructions further back in time. One way to obviate this is to sample desert marginal areas that only become active during significant arid phases. An alternative is to find and sample deep stratigraphic exposures. The Mamatwan manganese mine at Hotazel in the SW Kalahari meets both these criteria. Luminescence dating of this site shows the upper sedimentary unit to span at least the last 60 ka with tentative age estimates from underlying cemented aeolian units dating back to the last interglacial and beyond. Results from Mamatwan are comparable to new and previously published data from linear dunes in the SW Kalahari but extend back much further. Analysis of the entire data set of luminescence ages for the SW Kalahari brings out important inferences that suggest that different aeolian forms (1) have been active over different time scales in the past, (2) have different sensitivities to environmental changes and (3) have different time scales over which they record and preserve the palaeoenvironmental record. This implies that future optically stimulated luminescence work and palaeoenvironmental reconstructions must consider both site location and its relationship to desert margins and sediment depositional styles, so that the resolution and duration of the aridity record can be optimally understood

    Beyond balancing? Intrastate conflict and US grand strategy

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    ArticleThis is the author accepted manuscript. The final version is available from Taylor & Francis (Routledge) via the DOI in this record.Grand strategic theorists share an historical emphasis on interstate conflict. However, of some two hundred and seventy-three US military deployments since 1900, only seven were interstate conflicts. The rest were intrastate, domestic level engagements. We argue that these intrastate conflicts limit the utility of regional balances of power in mitigating forms of conflict that the US may consider inimical to its national security interests. When considering potential changes to US force posture and grand strategy, American coercive statecraft should be theorised along a broader strategic continuum encompassing the full range of conflict
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