132 research outputs found

    Wing-tip vanes as vortex attenuation and induced drag reduction devices

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    Analytical studies have been conducted to examine the feasibility of utilizing wing tip turbines to remove swirl from the wing trailing vortex, and hence reduce the potential for upset of following aircraft. Energy recovery from the turbines is also analyzed. A computer routine has been developed to permit rapid parametric studies of various tip turbine designs. It is shown that the optimum turbine is a non-rotating set of vanes which reduce swirl and recover energy in the form of reduced overall configuration induced drag. A specific case study indicates a 23% reduction in induced drag for a rectangular wing of aspect ratio 5.33, operated at a lift coefficient at 1.0

    Vortex sheet modeling with higher order curved panels

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    A method to predict the shape of the vortex sheet in the vicinity of its generating lifting surface is presented. The method uses potential flow vortex panels with a bilinear vorticity distribution and bicubic position interpolant to enable continuity to the necessary order. Positions of the panel nodes of successive streamwise stations are iteratively updated using the induced velocities computed from the sheet\u27s configuration during the previous cycle;Complex wing loadings can be used, such as the case of deployed partial span flaps, or stalled conditions. However, the spanwise node density must be adjusted accordingly;Good correlation was obtained for a simply loaded wing tested in the Boeing Company Research Wind Tunnel, and the results show a considerable improvement over current methods of prediction which use discrete vortex filaments;Such a method would be useful in predicting certain stability derivatives in various flight regimes, as well as in the evaluation of the induced effects on other aircraft surfaces

    Vortex sheet modeling with higher order curved panels

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    A numerical technique is presented for modeling the vortex sheet with a deformable surface definition, along which a continuous vortex strength distribution in the spanwise direction is applied, so that by repeatedly modifying its shape, its true configuration is approached, in the proximity of its generating wing. Design problems requiring the inclusion of a realistic configuration of the vortex sheet are numerous. Examples discussed include: control effectiveness and stability derivatives, longitudinal stability, lateral stability, canards, propellers and helicopter rotors, and trailing vortex hazards

    The Role Of Reputation In Market Entry: Evidence From French Public Procurement

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    This article studies the impact of reputation on market entry in public procurement. Based on the observation of a French firm with a strong reputation, we demonstrate a significant effect of the difference in public contracts won between date t-1 and date t. Our model provides empirical proof that selection of a supplier with a strong reputation does not hinder entry in public procurement nor does it prevent free competition. This result thus questions the justification for the European Union regulation that limits the use of information on past performance to select suppliers in public markets. The findings also suggest that reputation mechanisms can help reduce uncertainty during contract execution.

    PELATIHAN KONDISI FISIK PELATIH CABANG OLAHRAGA KOTA TANGERANG DALAM RANGKA PERSIAPAN PORPROV BANTEN 2022

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    Permasalahan latihan Fisik dan penyusunan program latihan fisik terkadang diabaikan baik itu dalam program dan pembinaan atlet yang berprestasi baik ditingkat Provinsi, Nasional maupun Internasional. Penelitian ini bertujuan untuk mengetahui Pelatihan kondisi fisik pada para pelatih cabang olahraga kota Tangerang dalam rangka Persiapan Porprov Banten 2022. Penelitian ini menggunakan metode survei. Sampel dalam penelitian ini adalah para Pelatih cabang olahraga Kota Tagerang. Teknik analisis data yang digunakan dalam penelitian ini adalah menggunakan analisis deskriptif. Penelitian tentang  Pelatihan kondisi fisik pada para Pelatih cabang olahraga Kota Tangerang Dalam Rangka Persiapan  Porprov Banten 2022 agar para pelatih memahami tentang pentingnya latihan fisik, membuat program latihan Fisik. Semua yang terlibat dalam pelatihan ini harus mendapatkan pembekalan yang mendalam agar dapat menyusun dan membuat program latihan dengan tepat sesuai sasaran atau tujuan di Porprov 2022 dan mencapai prestasi yang optimal dan dimana sekaligus Kota Tangerang menjadi Juara Umum Pada Porprov Banten 202

    Constraints on the evolution of Taranaki Fault from thermochronology and basin analysis: Implications for the Taranaki Fault play

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    Taranaki Fault is the major structure defining the eastern margin of Taranaki Basin and marks the juxtaposition of basement with the Late Cretaceous-Paleogene succession in the basin. Although the timing of the basement over-thrusting on Taranaki Fault and subsequent marine onlap on to the basement block are well constrained as having occurred during the Early Miocene, the age of formation of this major structure, its character, displacement history and associated regional vertical movement during the Late Cretaceous- Recent are otherwise poorly known. Here we have applied (i) apatite fission track thermochronology to Mesozoic basement encountered in exploration holes and in outcrop to constrain the amount and timing of Late Cretaceous-Eocene exhumation of the eastern side of the fault, (ii) basin analysis of the Oligocene and Miocene succession east of the fault to establish the late-Early Miocene - Early Pliocene subsidence history, and (iii), regional porosity-bulk density trends in Neogene mudstone to establish the late uplift and tilting of eastern Taranaki Basin margin, which may have been associated with the main period of charge of the underlying Taranaki Fault play. We make the following conclusions that may be useful in assessing the viability of the Taranaki Fault play. (1) Mid-Cretaceous Taniwha Formation, intersected in Te Ranga-1 was formerly extensive across the western half of the Kawhia Syncline between Port Waikato and Awakino. (2) Taranaki Fault first formed as a normalfault during the Late Cretaceous around 85±10 Ma, and formed the eastern boundary of the Taranaki Rift-Transform basin. (3) Manganui Fault, located onshore north of Awakino, formed as a steeply east dipping reverse fault and accommodated about four km of displacement during the mid-Cretaceous. (4) Uplift and erosion, involving inversion of Early Oligocene deposits, occurred along the Herangi High during the Late Oligocene. This may have been associated with initial reverse movement on Taranaki Fault. (5) During the Early Miocene (Otaian Stage) the Taranaki and Manganui Faults accommodated the westward transport of Murihiku basement into the eastern margin of Taranaki Basin, but the amount of topography generated over the Herangi High can only have been a few hundred metres in elevation. (6) The Altonian (19-16 Ma) marked the start of the collapse of the eastern margin of Taranaki Basin that lead during the Middle Miocene to the eastward retrogradation of the continental margin wedge into the King Country region. During the Late Miocene, from about 11 Ma, a thick shelf-slope continental margin wedge prograded northward into the King Country region and infilled it (Mt Messenger, Urenui, Kiore and Matemateaonga Formations). (7) During the Pliocene and Pleistocene the whole of central New Zealand, including the eastern margin of Taranaki Basin, became involved in long wavelength up-doming with 1-2 km erosion of much of the Neogene succession in the King Country region. This regionally elevated the Taranaki Fault play into which hydrocarbons may have migrated from the Northern Graben region

    When Revolution Meets Design Studio: Initiating academic debate on “a new urban order”

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    In the context of the January 2011 Revolution, architects and planners in Egypt were inspired by the revolutionary process. They envisioned new modes of pedagogy and professional practice. This paper exposes an initiative led by the Architectural Department at Cairo University to develop the 2011 graduation project as a contribution to the ongoing restructuring of the city and public space into citizen-initiated and inclusive settings for emerging social and political orders. This paper documents the work of 16 students, each with his or her particular site and project, within the broader framework of the “Building Legitimacy” mashru‘ (project). It critically discusses the limitations and challenges encountered during the process and reflects on the capacity of the Studio to contribute to the wider urban debate in Egypt.Après le 25 janvier 2011, architectes et urbanistes se sont inspirés du processus révolutionnaire pour imaginer de nouvelles pédagogies et de nouvelles pratiques professionnelles. Cet article décrit une initiative pilotée par le département d’architecture de l’Université du Caire, dont les projets de fin d’étude visent à contribuer à la restructuration du Caire et de ses espaces publics. La promotion 2011 a cherché à faire de ces contributions des projets laissant l’initiative aux citoyens, en accord avec un ordre social et politique émergeant. L’article rend compte du travail de 16 étudiant-e-s, chacun-e avec sur un site ou un projet particulier, dans le cadre plus général d’un projet baptisé « Building Legitimacy ». Il aborde de manière critique les limites et défis rencontrés au cours de la démarche et s’interroge sur la capacité de l’atelier à contribuer à un débat urbain plus large en Egypte
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