1,745 research outputs found

    Least weight and least cost optimisation of a passenger vessel

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    In the scantling design of a passenger ship, minimum production costminimum weight and maximum moment of inertia (stiffness) are conflicting objectives. For that purpose, recent improvements have been made to the LBR-5 software (French acronym of Stiffened Panels Software”, version 5.0) to optimize the scantling of ship sections by considering production cost, weight and moment of inertia in the optimisation objective function. A real multi-criterion optimisation of a passenger ship is presented in this paper. Results highlight that LBR-5 is competitive software to optimise scantling of ships at very early design stage with management of critical problems studied normally at a later step of the design

    Multi-criterion scantling optimisation of cruise ships

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    A numerical tool for the optimisation of the scantlings of a ship is extended by considering production cost, weight and moment of iner tia in the objective function. A multi-criteria optimisation of a passenger ship is conducted to illustrate the analysis process. Pareto frontiers are obtained and results are verified with Bureau Veritas rules

    Magnetohydrodynamics (MHD) Engineering Test Facility (ETF) 200 MWe power plant. Design Requirements Document (DRD)

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    A description and the design requirements for the 200 MWe (nominal) net output MHD Engineering Test Facility (ETF) Conceptual Design, are presented. Performance requirements for the plant are identified and process conditions are indicated at interface stations between the major systems comprising the plant. Also included are the description, functions, interfaces and requirements for each of these major systems. The lastest information (1980-1981) from the MHD technology program are integrated with elements of a conventional steam electric power generating plant

    Weight gain composition in preterm infants with dual energy x-ray absorptiometry

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    Emergence of pointer states in a non-perturbative environment

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    We show that the pointer basis distinguished by collisional decoherence consists of exponentially localized, solitonic wave packets. Based on the orthogonal unraveling of the quantum master equation, we characterize their formation and dynamics, and we demonstrate that the statistical weights arising from an initial superposition state are given by the required projection. Since the spatial width of the pointer states can be obtained by accounting for the gas environment in a microscopically realistic fashion, one may thus calculate the coherence length of a strongly interacting gas.Comment: 8 pages, 1 figure; corresponds to published versio

    "Brace technology" thematic series - the Gensingen brace™ in the treatment of scoliosis

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    <p>Abstract</p> <p>Background</p> <p>Bracing concepts in use today for the treatment of scoliosis include symmetric and asymmetric hard braces usually made of polyethylene (PE) and soft braces. A new asymmetric Chêneau style CAD/CAM derivate has been designed to overcome problems the author experienced with other Chêneau CAD/CAM systems over the recent years.</p> <p>Brace description</p> <p>This CAD/CAM Chêneau derivate has been called Gensingen brace™, a brace available to address all possible curve patterns. Once the patients' trunk is scanned with the help of a whole trunk optical 3D-scan and the patients' data from the clinical measurements are recorded, a model of the brace can be created by (1) modifying the trunk model of the patient 'on screen' to achieve a very individual brace model using the CAD/CAM tools provided or by (2) choosing a brace model from our library and re-size it to the patients' properties 'on screen'.</p> <p>Results</p> <p>End-result studies have been published on the Chêneau brace as early as 1985. Cohort studies on the Chêneau brace are available as is a prospective controlled study respecting the SRS criteria for bracing studies, demonstrating beneficial outcomes, when compared to the controls using a soft brace. Sufficient in-brace correction effects have been demonstrated to be achievable when the Chêneau principles of correction are used appropriately. As there is a positive correlation between in-brace correction and the final outcome, the Chêneau concept of bracing with sufficient in-brace corrections as published can be regarded as being efficient when applied well. Case reports with high in-brace corrections, as shown within this paper using the Gensingen brace™ promise beneficial outcomes when a good compliance can be achieved.</p> <p>Conclusions</p> <p>The use of the Gensingen brace™ leads to sufficient in-brace corrections, when compared to the correction effects achieved with other braces, as described in literature.</p> <p>According to the patients' reports, the Gensingen brace™ is comfortable to wear, when adjusted properly.</p> <p>Further studies are necessary (1) in order to evaluate brace comfort and (2) effectiveness using the SRS inclusion criteria.</p

    Computing the kk-binomial complexity of the Thue--Morse word

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    Two words are kk-binomially equivalent whenever they share the same subwords, i.e., subsequences, of length at most kk with the same multiplicities. This is a refinement of both abelian equivalence and the Simon congruence. The kk-binomial complexity of an infinite word x\mathbf{x} maps the integer nn to the number of classes in the quotient, by this kk-binomial equivalence relation, of the set of factors of length nn occurring in x\mathbf{x}. This complexity measure has not been investigated very much. In this paper, we characterize the kk-binomial complexity of the Thue--Morse word. The result is striking, compared to more familiar complexity functions. Although the Thue--Morse word is aperiodic, its kk-binomial complexity eventually takes only two values. In this paper, we first obtain general results about the number of occurrences of subwords appearing in iterates of the form Ψ(w)\Psi^\ell(w) for an arbitrary morphism Ψ\Psi. We also thoroughly describe the factors of the Thue--Morse word by introducing a relevant new equivalence relation

    Thermal Treatments of AlSi10Mg Processed by Laser Beam Melting

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    Recent studies have shown that AlSi10Mg processed by Laser Beam Melting (LBM) exhibits a much finer microstructure when compared to its cast counterpart as a consequence of the much faster cooling rates imposed in the LBM process. Such microstructural refinement causes a significant increase in strength and hardness, to such an extent that as-fabricated LBM AlSi10Mg was reported to present hardness value of 127 ± 3 Hv0.5, similar to the hardness of high pressure die cast AlSi10Mg in the aged condition (i.e. 130-133 Hv). Yet, little attention has been given so far to the influence of thermal treatments on the microstructure and mechanical behavior of LBM AlSi10Mg. The present work hence aims to investigate the effect of two different types of heat treatments – i.e. (i) stress relief and (ii) solutionizing and ageing − on the microstructure, hardness and tensile properties of LBM AlSi10Mg.Mechanical Engineerin
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