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Articles de revues sur le sujet « SPARS »

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Auteur : Grafiati
Publié le 11 septembre 2023

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1

Rosenzweig, Michael L. « Reconciliation ecology and the future of species diversity ». Oryx 37, no 2 (avril 2003) : 194–205. http://dx.doi.org/10.1017/s0030605303000371.

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Species-area relationships (SPARs) dictate a sea change in the strategies of biodiversity conservation. SPARs exist at three ecological scales: Sample-area SPARs (a larger area within a biogeographical province will tend to include more habitat types, and thus more species, than a smaller one), Archipelagic SPARs (the islands of an archipelago show SPARs that combine the habitat-sampling process with the problem of dispersal to an island), and Interprovincial SPARs (other things being equal, the speciation rates of larger biogeographical provinces are higher and their extinction rates are lower, leading to diversities in proportion to provincial area). SPARs are the products of steady-state dynamics in diversity, and such dynamics appears to have characterized the earth for most of the last 500 million years. As people reduce the area available to wild species, they impose a linear reduction of the earth's species diversity that will follow the largest of these scales, i.e. each 1% reduction of natural area will cost about 1% of steady-state diversity. Reserving small tracts of wild habitat can only delay these reductions. But we can stop most of them by redesigning anthropogenic habitats so that their use is compatible with use by a broad array of other species. That is reconciliation ecology. Many pilot projects, whether intentionally or inadvertently espousing reconciliation ecology, are demonstrating that it can be done.
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2

Alex Tullo. « Braskem spars with Pemex ». C&EN Global Enterprise 98, no 47 (7 décembre 2020) : 10. http://dx.doi.org/10.1021/cen-09847-buscon6.

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3

ENNOS, A. ROLAND. « The Importance of Torsion in the Design of Insect Wings ». Journal of Experimental Biology 140, no 1 (1 novembre 1988) : 137–60. http://dx.doi.org/10.1242/jeb.140.1.137.

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A model insect wing is described in which spars of corrugated membrane which incorporate stiffening veins branch serially from a V-section leading edge spar. The mechanical behaviour of this model is analysed. The open, corrugated spars possess great resistance to bending, but are compliant in torsion. Torsion of the leading edge spar will result in torsion and relative movement of the rear spars. As a result camber will automatically be set up in the wing as it twists. Aerodynamic forces produced during the wing strokes will result in torsion and camber of the wing which should improve its aerodynamic efficiency. The effects of varying parameters of the wing model are examined. For given wing torsion, higher camber is given by spars branching from the leading edge at a lower angle, by spars which curve posteriorly, and by spars which diverge from each other. Wings of three species of flies were each subjected to two series of mechanical tests. Application of a force behind the torsional axis caused the wings to twist and to develop camber. Immobilizing basal regions of the leading edge greatly reduced compliance to torsion and camber, as predicted by the theoretical model. Aerodynamic forces produced during a half-stroke are sufficient to produce observed values of torsion and camber, and to maintain changes in pitch caused by inertial effects at stroke reversal.
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4

Hayat, Khazar, Shafaqat Siddique, Tipu Sultan, Hafiz T. Ali, Fahed A. Aloufi et Riyadh F. Halawani. « Effect of Spar Design Optimization on the Mass and Cost of a Large-Scale Composite Wind Turbine Blade ». Energies 15, no 15 (2 août 2022) : 5612. http://dx.doi.org/10.3390/en15155612.

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Mass and cost tradeoffs by deploying three optimized spars, made of all-glass, hybrid and all-carbon composites, applied to a publicly available large-scale composite blade of 100 m in length for a 13.2 MW wind turbine, are explored. The blade mass and cost minimizations are calculated for two design load cases, generating the worst aerodynamic loads for parked and rotating rotor blades, while meeting the stiffness, strength, stability and resonance design requirements, as recommended by the wind turbine standards. The optimization cases are formulated as a single-objective, multi-constraint optimization problem, while taking into account the manufacturability of hybrid spars in particular, and it is solved using a genetic algorithm method. The blade mass lowers in the range of 8.1–13.3%, 18.5–20.7% and 25.7–26.4% for the optimized all-glass, hybrid and all-carbon spars, respectively, while the cost decreases for the optimized all-glass spars only. The cost increases in a range of 1.2–13.6% and 24.5–31.5% when the optimized hybrid and all-carbon spars are used. Further, the hybrid spar optimization using the blade mass and cost objective functions, as well as the effects of spar optimization on the blade’s structural performance in terms of tip deflection, strength, buckling resistance and first natural frequency, are discussed.
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5

Qasim, Isa C. « Navigating the Trunks and Spars ». New Criminal Law Review 24, no 4 (2021) : 518–67. http://dx.doi.org/10.1525/nclr.2021.24.4.518.

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In 2018, the Supreme Court issued a little noticed decision, Currier v. Virginia, that signaled a potential revolution in the Double Jeopardy Clause doctrine. This essay uses that decision to reconsider the Clause’s disparate protections, seeking coherence in this long-confused area of law. In doing so, it finds that the central protections of the Clause are best understood through a single, novel framework: the jury-preservation theory of double jeopardy. This essay explicates the theory, explaining its roots in the Revolutionary Era jury, its applications to modern double jeopardy law, and its implications for Currier and future double jeopardy cases.
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6

Finn, L. « Reliable Riser Systems for Spars ». Journal of Offshore Mechanics and Arctic Engineering 121, no 4 (1 novembre 1999) : 201–6. http://dx.doi.org/10.1115/1.2829568.

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The Spar concept as a floating vessel is now recognized as a reliable and economic option for developing deepwater offshore hydrocarbon reservoirs. Many of the advantages of the Spar concept are attributed to the variety of riser systems that can be accommodated. This paper presents a discussion of design considerations for the top tensioned and steel catenary risers deployed from a Spar offshore production vessel. Results from extreme event strength analysis, Spar motion and current-induced fatigue analysis, and a riser-to-riser wake interference analysis are presented. Steel catenary risers are presented, including a comparison of results for risers supported by a Spar and a Semi. These analyses demonstrate that simple and reliable riser systems can be designed for use with the Spar platform concept.
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7

Bramesfeld, Götz, et Ryan Prinster. « Design and testing of foam-inflated wings for small unmanned aerial vehicles ». Journal of Unmanned Vehicle Systems 3, no 4 (1 décembre 2015) : 176–91. http://dx.doi.org/10.1139/juvs-2014-0018.

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Inflatable wings can greatly improve the portability of small UAVs. The foam-inflated wing concept consists of a hybrid structure of rigid and flexible elements. This approach potentially reduces the packaging and logistical needs before deployment of a small UAV. The small packaging volume of the wing is achieved using spars and wing skin that are made out of flexible polyester-film material. For deployment, the cylindrical spars are rigidized using expanding foam that increases the buckling stiffness of the spars. Solid ribs that were previously attached to those spars provide high shape compliance for the external skin. Due to the solid rib structure, the chord length of the wing defines the maximum packing dimension before inflation. As demonstrated in tests, the inflation process of the hybrid wing is uncomplicated and swift. The subsequent foam-inflated structure is lightweight and can be tailored to the expected loads. In addition, the underlying ribs ensure a high aerodynamic quality, despite the inflatable nature of the hybrid wing structure. The feasibility of the concept of the hybrid wing structure has been demonstrated in flight tests.
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8

Vogel, G. « EDUCATION : California Spars Over Math Reform ». Science 277, no 5330 (29 août 1997) : 1194. http://dx.doi.org/10.1126/science.277.5330.1194.

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9

Perlman, Lisa. « Rocket spars as science is attacked ». Nature 344, no 6267 (avril 1990) : 578. http://dx.doi.org/10.1038/344578c0.

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10

Scholl, Bernd. « Klebstoffe geben Gas — schnell, zuverlässig, spars ». adhäsion KLEBEN & ; DICHTEN 61, no 12 (décembre 2017) : 30–33. http://dx.doi.org/10.1007/s35145-017-0094-7.

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11

Naing, Lin Aung, W. A. Phyo et O. V. Tatarnikov. « Selection of the Optimal Load Bearing Wing Structure Scheme for an Unmanned Aerial Vehicle ». Proceedings of Higher Educational Institutions. Маchine Building, no 11 (728) (novembre 2020) : 89–95. http://dx.doi.org/10.18698/0536-1044-2020-11-89-95.

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This article presents the results of optimization of the load bearing structure of the wing of an unmanned aerial vehicle. The criteria and optimization parameters were considered, respectively: the minimum wing mass, number of spars and ribs, location parameters of the spars and ribs, and thickness of the wing's load bearing elements. The maximum wing deflection was considered as a limiting factor. The calculated model took into account the change in the thickness of the spars along the direction of the wingspan, while the thickness of the skin and ribs was considered as constant. The optimal load bearing scheme of the wing was selected by the criterion of the minimum wing mass based on the maximum permissible deflection of the wing. Calculations of the stress-strain state of the wing were performed using a finite element model in the FEMAP software package.
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12

Marvin R. Pyles, James E. Ammeson et John W. Mann. « static Field Testing of Guyed Logging Spars ». Transactions of the ASAE 31, no 4 (1988) : 1027–32. http://dx.doi.org/10.13031/2013.30817.

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13

Ammeson, James E., Marvin R. Pyles et Harold I. Laursen. « Three-dimensional analysis of guyed logging spars ». Computers & ; Structures 29, no 6 (janvier 1988) : 1095–99. http://dx.doi.org/10.1016/0045-7949(88)90333-1.

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14

Lahiri, Saibendu Kumar. « Pedagogy in Undergraduate teaching programme – different spars ». Journal of Comprehensive Health 7, no 1 (30 juin 2019) : 1. http://dx.doi.org/10.53553/jch.v07i01.001.

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Pedagogy means science of teaching. It tries to bring about the desirable change in behaviour of the students under supervision of the teachers. It has got teacher at one pole and student at the other with the system of flowing of knowledge and acceptance keeping the scope of bilateral exchange which make the science viable and ever-changing with fresh inputs of thoughts.Undergraduate medical courses are primarily taught in lecture format. Apart from this, seminars, symposium, panel discussion, group discussion, programmed learning, work shop, role playing, counselling, brain storming, practical, tutorial, demonstration, clinical simulation are used as method of teaching. Group involvement is ensured in epidemiological and family projects. Audio-visual aids like over head projector (OHP), power-point presentation, and video are effectively used in several teaching-learning methods. Student learning is evaluated with theory papers, items, objective structured clinical/ practical examinations (OSCE/OSPE), clinical and community level examinations.
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15

Grbović, Aleksandar, Gordana Kastratović, Aleksandar Sedmak, Igor Balać et Mihajlo D. Popović. « Fatigue crack paths in light aircraft wing spars ». International Journal of Fatigue 123 (juin 2019) : 96–104. http://dx.doi.org/10.1016/j.ijfatigue.2019.02.013.

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16

Dovbush, Taras, Nadia Khomyk, Hanna Tson et Anatoliy Dovbush. « Improvement of prt-9 constructive system on the basis of frame elements strength balance ». Scientific journal of the Ternopil national technical university 100, no 4 (2020) : 40–45. http://dx.doi.org/10.33108/visnyk_tntu2020.04.040.

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Analytical and experimental investigations of the most loaded elements of the base frame of PRT-9 solid organic fertilizer spreader are carried out in this paper. The residual operation life of the central beam of the paired Z-shaped profile, as well as the lateral spars of the Z-shaped cross section are determined. According to the results of studies, it was found that the residual operation life of these system elements differ significantly. In order to achieve strength uniformity of the main frame elements, it is decided to weaken the central beam by replacing the paired Z-shaped profile with a thin-walled tube of rectangular cross-section and strengthen the lateral spars by replacing Z-shaped profile with a channel profile with the same height.
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17

Gavish, Yoni. « Questioning Israel's Great Biodiversity—Relative to Whom ? A Comment on Roll et al., 2009 ». Israel Journal of Ecology and Evolution 57, no 3 (6 mai 2011) : 183–92. http://dx.doi.org/10.1560/ijee.57.3.183.

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Each evolutionary-independent province has its own mainland species area relationship (SPAR). When using the power law SPAR (S = cAz), separate mainland SPARs are parallel in a log-log space (similar z value), yet they differ in species density per unit area (c value). This implies that there are two main SPAR-based strategies to identify biodiversity hotspots. The first treats all mainland SPARs of all provinces as if they form one global SPAR. This is the strategy employed by Roll et al. (2009) when questioning Israel's high biodiversity. They concluded that Israel is not a global biodiversity hotspot. Their results may arise from the fact that Israel's province, the Palaearctic, is relatively poor. Therefore, countries from richer provinces, whose mainland SPAR lies above the Palaearctic SPAR, are identified as global hotspots. The second strategy is to construct different mainland SPARs for each province and identify the provincial hotspots. In this manuscript I ask whether Israel's biodiversity is high relative to other countries within its province. For six different taxa, I analyzed data for Palaearctic countries. For each taxon, I conducted a linear regression of species richness against the country's area, both log transformed. The studentized residuals were used to explore Israel's rank relative to all other Palaearctic countries. I found that Israel lies above the 95th percentile for reptiles and mammals and above the 90th percentile for birds. Therefore, within the Palaearctic province, Israel is indeed a biodiversity hotspot.
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18

Wen, Ting, Kai Wang, Zhengshun Cheng et Muk Ong. « Spar-Type Vertical-Axis Wind Turbines in Moderate Water Depth : A Feasibility Study ». Energies 11, no 3 (5 mars 2018) : 555. http://dx.doi.org/10.3390/en11030555.

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The applications of floating vertical-axis wind turbines (VAWTs) in deep water have been proposed and studied by several researchers recently. However, the feasibility of deploying a floating VAWT at a moderate water depth has not yet been studied. In this paper, this feasibility is thoroughly addressed by comparing the dynamic responses of spar-type VAWTs in deep water and moderate water depth. A short spar VAWT supporting a 5 MW Darrieus rotor at moderate water depth is proposed by following the deep spar concept in deep water. A fully coupled simulation tool, SIMO-RIFLEX-DMS code, is utilized to carry out time domain simulations under turbulent wind and irregular waves. Dynamic responses of the short spar and deep spar VAWTs are analyzed and compared, including the natural periods, wind turbine performance, platform motions, tower base bending moments, and tension of mooring lines. The statistical characteristics of the thrust and power production for both spars are similar. The comparison of platform motions and tower base bending moments demonstrate a good agreement for both spars, but the short spar has better performance in surge/sway motions and side–side bending moments. The 2P response dominates the bending moment spectra for both spars. A significant variation in tension of Mooring Line 1 and a larger corresponding spectrum value are found in the short spar concept. The results indicate that the application of short spar VAWTs is feasible and could become an alternative concept at moderate water depth.
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19

Sairam, S. Karthik, et T. Ramakrishnaiah. « Detection of PUE Attack by SPARS Model using WSPRT ». International Journal of Science and Engineering Applications 4, no 5 (19 septembre 2015) : 269–72. http://dx.doi.org/10.7753/ijsea0405.1007.

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20

Chen, Zhao. « Mechanical analysis of tree spars in cable yarding systems ». Journal of Northeast Forestry University 4, no 2 (novembre 1993) : 103–11. http://dx.doi.org/10.1007/bf02843081.

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21

Меланченко, Александр Геннадиевич, et Александр Александрович Синча. « DECENTRALIZED PACKET TASK ALLOCATION FOR SPARS CLUSTER OF SPACECRAFT ». Information systems, mechanics and control, no 14 (25 avril 2016) : 130–41. http://dx.doi.org/10.20535/2219-380414201670332.

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Marvin R. Pyles. « Structural Properties of Second-Growth Douglas-Fir Logging Spars ». Transactions of the ASAE 30, no 1 (1987) : 0065–69. http://dx.doi.org/10.13031/2013.30403.

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23

Nagarajan, V. A., S. Sundaram, K. Thyagarajan, J. Selwin Rajadurai et T. P. D. Rajan. « Refined Delamination Factor Failure Characterization of Composite Wind Turbine Blade ». International Journal of Damage Mechanics 21, no 8 (21 décembre 2011) : 1227–44. http://dx.doi.org/10.1177/1056789511432790.

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Wind turbines are used to convert the kinetic energy of wind into useful power. The wind turbine blades are fabricated using glass fiber-reinforced composite materials. Wind turbine blades are complex section. In order to improve the strength of the blades under varying loading conditions, spars are embedded in it. The spars are fastened with the composite shells of the blades using bolted connections. In order to affect this fastening, holes of appropriate size were drilled in the composite laminates. Delamination is the major failure in composite blades which is induced during drilling. Delamination is quantitatively measured using digital means. A comparison between the conventional ( FD) and adjusted ( FDA) delamination factors is presented. In order to effectively quantify the delamination, refined delamination factor ( FDR) is proposed. It is found that the proposed FDR predicts the failure in a better manner when compared with predictive capabilities of FD as well as FDA.
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24

Rodzewicz, Mirosław, et Jerzy Lewitowicz. « Lightness Factors and Exertion Factors Related to its Own Mass of Fiber Reinforced Plastics (FRP) Applied in Composite Aeronautical Structures (Part 1) ». Journal of KONBiN 47, no 1 (1 octobre 2018) : 5–22. http://dx.doi.org/10.2478/jok-2018-0036.

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Abstract The paper concerns an application of lightness factors in comparative analysis of strength properties of basic materials being applied in aeronautical structures – in a historical perspective. The use of lightness factors enables effective estimation how lighter will be the structural elements (of the same strength or stiffness) made from different kind of materials : traditional as well as advanced composites. It is quite easy to find the solution to the inverse problem, i.e. to estimate how differ will be stiffness or strength for the same mass of the structural elements. Very particular application of the lightness factors are noted in engineers calculations of composite gliders wing spars, where they appears as the materials constants and as structure loading factors as well. The paper presents some examples of application of the lightness factors in strength analysis of the composite shells applied in the shear webs of the wing spars, and refers to the design recommendations issued by German aviation authority (LBA).
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Rodzewicz, Mirosław, et Jerzy Lewitowicz. « Lightness Factors and Exertion Factors Related to its Own Mass of Fiber Reinforced Plastics (FRP) Applied in Composite Aeronautical Structures (Part 2) ». Journal of KONBiN 47, no 1 (1 octobre 2018) : 23–43. http://dx.doi.org/10.2478/jok-2018-0037.

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Abstract The paper concerns an application of lightness factors in comparative analysis of strength properties of basic materials being applied in aeronautical structures – in a historical perspective. The use of lightness factors enables effective estimation how lighter will be the structural elements (of the same strength or stiffness) made from different kind of materials : traditional as well as advanced composites. It is quite easy to find the solution to the inverse problem, i.e. to estimate how differ will be stiffness or strength for the same mass of the structural elements. Very particular application of the lightness factors are noted in engineers calculations of composite gliders wing spars, where they appears as the materials constants and as structure loading factors as well. The paper presents some examples of application of the lightness factors in strength analysis of the composite shells applied in the shear webs of the wing spars, and refers to the design recommendations issued by German aviation authority (LBA).
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26

Fischer, F. J., et R. Gopalkrishnan. « Some Observations on the Heave Behavior of Spar Platforms ». Journal of Offshore Mechanics and Arctic Engineering 120, no 4 (1 novembre 1998) : 221–25. http://dx.doi.org/10.1115/1.2829543.

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The spar platform is receiving considerable attention from the offshore petroleum industry, especially following the successful introduction of the first production spar in the Gulf of Mexico by Oryx and CNG in 1996. This paper presents a collection of observations regarding important heave characteristics of spar platforms that have been gleaned from wave-basin model tests, numerical simulations, and comparisons of the two. These observations are pertinent to the heave performance of “classic” (uniform-cylinder) spars. Excessive spar heave could be problematic for production and export risers. Spar-system characteristics affecting heave include draft, heave natural period, heave-damping augmentation, and presence/absence of a vertical tether/tendon. Tether requirements for shallow-draft spars have been found to be much less onerous than once thought; steel tethers yielding a heave natural period of 12 s have been found to be satisfactory. Heave-damping augmentation using multiple “plates” or “disks,” following the work of Troesch at the University of Michigan, has also been found to be quite attractive.
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Korpus, R. A., et S. Liapis. « Active and Passive Control of Spar Vortex-Induced Motions ». Journal of Offshore Mechanics and Arctic Engineering 129, no 4 (9 février 2007) : 290–99. http://dx.doi.org/10.1115/1.2746400.

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Spars have become an “industry solution” for deepwater developments. Vortex-induced motion (VIM) of spar platforms in currents remains an important design concern. Although strakes are effective at suppressing riser VIM, all three straked classical spars in the Gulf of Mexico have experienced significant VIM events. These are not examples of poor design but indicate a lack of adequate tools for predicting spar VIM. This paper presents the development and validation of unsteady Reynolds-averaged Navier-Stokes (URANS) methods to predict real-world spar VIM behavior. It includes the ability to address rough surfaces and high supercritical Reynolds numbers. The resulting algorithms are used to assess the effectiveness of active and passive control strategies for suppressing spar VIM. Active control consists of injecting high-pressure water tangentially into the boundary layer and is shown to be extremely effective at reducing drag and VIM amplitudes. Passive control utilizes a sleeve to channel high-pressure stagnation flow into the boundary layer and is found less effective.
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Locatelli, Davide, Sameer B. Mulani et Rakesh K. Kapania. « Wing-Box Weight Optimization Using Curvilinear Spars and Ribs (SpaRibs) ». Journal of Aircraft 48, no 5 (septembre 2011) : 1671–84. http://dx.doi.org/10.2514/1.c031336.

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Anam, Iftekhar, et Jose M. Roesset. « Effect of Nonlinear Wave Kinematics on Dynamic Response of Spars ». Journal of Engineering Mechanics 128, no 9 (septembre 2002) : 925–34. http://dx.doi.org/10.1061/(asce)0733-9399(2002)128:9(925).

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Aung, Naing Lin, Oleg Tatarnikov et Phyo Wai Aung. « Optimization of composite wing spars for an unmanned aerial vehicle ». IOP Conference Series : Materials Science and Engineering 971 (1 décembre 2020) : 052076. http://dx.doi.org/10.1088/1757-899x/971/5/052076.

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31

Downie, M. J., J. M. R. Graham, C. Hall, A. Incecik et I. Nygaard. « An experimental investigation of motion control devices for truss spars ». Marine Structures 13, no 2 (mars 2000) : 75–90. http://dx.doi.org/10.1016/s0951-8339(00)00010-1.

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Salaffi, Fausto, Marina Carotti, Eleonora Di Donato, Marco Di Carlo, Michele Maria Luchetti, Luca Ceccarelli et Andrea Giovagnoni. « Preliminary validation of the Simplified Psoriatic Arthritis Radiographic Score (SPARS) ». Skeletal Radiology 48, no 7 (7 décembre 2018) : 1033–41. http://dx.doi.org/10.1007/s00256-018-3124-0.

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33

Saravi, Albert, et C. Kevin Lyons. « Finite element modeling of guyed back spars in cable logging ». Canadian Journal of Forest Research 34, no 4 (1 avril 2004) : 817–28. http://dx.doi.org/10.1139/x03-250.

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In this study a finite element model of a back spar system was developed with three guylines opposing the skyline strap tension. In this paper the allowable skyline strap tension is the tension in the skyline strap that results in the maximum normal stress on a transverse cross section of the tree being equal to an assumed allowable stress. An iterative routine was developed to find the allowable skyline strap tension, and this routine was found to converge rapidly from initial values that were below and above the allowable skyline strap tension. Two algorithms were developed for finding the maximum normal stress on a transverse cross section of a tree, method 1 and method 2. If the plane that the tree displaced in was known a priori, then method 2 could be used, and it was found to be less sensitive to mesh coarseness. If the plane that the tree displaced in was not known a priori, then method 1 had to be used with a less coarse mesh. It was found that the stress concentrations due to simplified cable connections were not significant for rigging configurations that allowed a larger rigging point displacement. The rigging configurations that allowed larger rigging point displacements have stress fields that are dominated by bending, while for rigging configurations that allow only small rigging point displacements, the stress fields are dominated by axial compression.
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Al-Maliky, Firas Thair, et Dhurgham A. Kadhim. « Optimizing of Turbine blade spar using Ansys program ». Journal of Petroleum Research and Studies 12, no 1(Suppl.) (21 avril 2022) : 302–15. http://dx.doi.org/10.52716/jprs.v12i1(suppl.).639.

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The current work involved optimizing the spars of wind turbine blades while taking into account the wind speed quantities that affected the blade structure. The objective was to determine the optimal dimensions of turbine blade spar configurations using the finite element method under the influence of the maximum pressure associated with the first mode shape while maintaining the Von Misses stresses within the assumed safety factor (1.5). (200-230 MPa). The blade was stiffened with a main box spar and two auxillary spars on each side. Appropriate spar locations were specified for poisons with a high natural frequency first mode. The blade parts' dimensions were discretized to allow for greater flexibility and precision in dimension assignment. By utilizing the ANSYS program, the optimization process required a certain number of iterations to modify the blade structure's dimensions. Optimized iteration was considered in order to increase the thickness in areas of high stress and decrease the thickness in areas of low stress. Additionally, a comparison between a blade structure with optimal dimensions and one with non-optimal dimensions was included.
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35

Bolton, Richard W. « Enabling Shipbuilding Supply Chain Virtual Enterprises ». Journal of Ship Production 17, no 02 (1 mai 2001) : 76–86. http://dx.doi.org/10.5957/jsp.2001.17.2.76.

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The Shipbuilding Partners and Suppliers (SPARS) Consortium proposes to deploy shipbuilding Supply Chain (SC) Virtual Enterprises (VEs) which will integrate the shipbuilding supply chain composed of customers, partners, subcontractors, and suppliers. Virtual Enterprises enable sourcing and supply chain integration to provide business process interactions among shipyards and suppliers that are transparent of the underlying processes and computing environments of the participants.
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Bishay, Peter L., Erich Burg, Akinwande Akinwunmi, Ryan Phan et Katrina Sepulveda. « Development of a New Span-Morphing Wing Core Design ». Designs 3, no 1 (7 février 2019) : 12. http://dx.doi.org/10.3390/designs3010012.

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This paper presents a new design for the core of a span-morphing unmanned aerial vehicle (UAV) wing that increases the spanwise length of the wing by fifty percent. The purpose of morphing the wingspan is to increase lift and fuel efficiency during extension, to increase maneuverability during contraction, and to add roll control capability through asymmetrical span morphing. The span morphing is continuous throughout the wing, which is comprised of multiple partitions. Three main components make up the structure of each partition: a zero Poisson’s ratio honeycomb substructure, telescoping carbon fiber spars and a linear actuator. The zero Poisson’s ratio honeycomb substructure is an assembly of rigid internal ribs and flexible chevrons. This innovative multi-part honeycomb design allows the ribs and chevrons to be 3D printed separately from different materials in order to offer different directional stiffness, and to accommodate design iterations and future maintenance. Because of its transverse rigidity and spanwise compliance, the design maintains the airfoil shape and the cross-sectional area during morphing. The telescoping carbon fiber spars interconnect to provide structural support throughout the wing while undergoing morphing. The wing model has been computationally analyzed, manufactured, assembled and experimentally tested.
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Nguyen, Quang Duy, Hoon Cheol Park, Taesam Kang et Jin Hwan Ko. « Structural design and analysis of composite blade for horizontal-axis tidal turbine ». Science and Engineering of Composite Materials 25, no 6 (27 novembre 2018) : 1075–83. http://dx.doi.org/10.1515/secm-2017-0093.

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AbstractIn this work, we report on the structural design of a 5-m-long composite blade intended for use in a horizontal-axis tidal turbine. The blade geometry is constructed through an optimization process to obtain the maximum power coefficient at the desired tip speed ratio of 4.5 by applying the blade element-momentum theory (BEMT). The blade is primarily designed using a NACA 63-424 hydrofoil. The blade structure is designed by using the BEMT to compute the loading conditions at various inflow velocities. Two parallel spars were chosen to produce the blade structure grid, and the preliminary lay-up structure of the composite blade was determined according to the thickness distribution identified using the twisted beam theory under the assumption that the two spars plus the upper and lower skins mostly contribute to the flap-wise bending stiffness while withstanding an external load. Then, high-strength unidirectional and double-bias fiber glass/epoxy materials were chosen to fabricate the blade. The final blade structure was then analyzed in ANSYS Workbench using the finite element method. The results show that the blade structure can withstand the applied load with failure indices <0.4.
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Locatelli, Davide, Sameer B. Mulani et Rakesh K. Kapania. « Parameterization of Curvilinear Spars and Ribs for Optimum Wing Structural Design ». Journal of Aircraft 51, no 2 (mars 2014) : 532–46. http://dx.doi.org/10.2514/1.c032249.

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Popov, Yu О., T. V. Kolokol’tseva et A. V. Khrul’kov. « The new generation of materials and technologies for helicopter blade spars ». «Aviation Materials and Technologies», S2 (2014) : 5–9. http://dx.doi.org/10.18577/2071-9140-2014-0-s2-5-9.

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Concilio, Antonio, Monica Ciminello, Bernardino Galasso, Lorenzo Pellone, Umberto Mercurio, Gianvito Apuleo, Aniello Cozzolino, Iddo Kressel, Shay Shoham et David Bardenstein. « De-Bonding Numerical Characterization and Detection in Aeronautic Multi-Element Spars ». Sensors 22, no 11 (30 mai 2022) : 4152. http://dx.doi.org/10.3390/s22114152.

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Structural health monitoring has multifold aims. Concerning composite structures, the main objectives are perhaps reducing costs by shifting from scheduled to on-demand maintenance and reducing weight by removing redundant precautions as the insertion of chicken fasteners to for ensuring joint safety in cases of bonding layer fail. Adhesion defects may be classified along different types, for instance distinguishing between glue deficiency or de-bonding. This paper deals with a preliminary numerical characterization of adhesive layer imperfections on a representative aircraft component. The multipart composite spar is made of two plates and two corresponding C-beams, bonded together to form an almost squared boxed section beam. A numerical test campaign was devoted to extract relevant information from different defect layouts and to try to assess some parameters that could describe their peculiarities. A focus was then given to macroscopic evidence of fault effects behavior, as localization, reciprocal interference, impact on structural response, and so on. A proprietary code was finally used to retrieve the presence and size of the imperfections, correlating numerical outcomes with estimations. Activities were performed along OPTICOMS, a European project funded within the Clean Sky 2 Joint Technology Initiative (JTI).
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Doman, David B., Chin pei Tang et Sean Regisford. « Modeling Interactions Between Flexible Flapping-Wing Spars, Mechanisms, and Drive Motors ». Journal of Guidance, Control, and Dynamics 34, no 5 (septembre 2011) : 1457–73. http://dx.doi.org/10.2514/1.53083.

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Visnjic, Goran, Dejan Nožak, Franc Kosel et Tadej Kosel. « Reducing shear-lag in thin-walled composite I-beam wing spars ». Aircraft Engineering and Aerospace Technology 86, no 2 (25 février 2014) : 89–98. http://dx.doi.org/10.1108/aeat-09-2012-0153.

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43

Roth-Johnson, Perry, Richard E. Wirz et Edward Lin. « Structural design of spars for 100-m biplane wind turbine blades ». Renewable Energy 71 (novembre 2014) : 133–55. http://dx.doi.org/10.1016/j.renene.2014.05.030.

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44

Nasoulis, Christos, Panagiotis Tsirikoglou et Anestis Kalfas. « Structural optimization of the wing box for a hybrid-electric commuter aircraft ». Journal of the Global Power and Propulsion Society 6 (11 août 2022) : 151–64. http://dx.doi.org/10.33737/jgpps/151116.

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Hybrid-electric commuter aircraft segment is playing a significant role in the electrification of air transportation. Towards the achievement of efficient and robust transportation, design and optimization processes are necessary to evaluate the different aircraft components. Within this context, the current work investigates the impact of the positioning of the propulsion system and spars on the structural integrity of a hybrid-electric commuter aircraft. The proposed approach is based on an in-house aircraft sizing tool, along with geometry generation and high-fidelity structural evaluation models. These tools are tailored in an automated computational pipeline, that includes pre-processing, model evaluation and post-processing tasks, able to perform design space exploration and optimization over different loading conditions of a selected mission envelope. This work focuses on the assessment of the impact of the additional non-structural weight e.g., batteries, fuel, and propulsion components, inside the wing box, on the stress, deformation and spanwise thickness distribution of the structure. The effect of spars and propulsion system positioning on the available storage space, maximum stress and displacement is discussed, with the aft spar having the greatest impact. Finally, the structural model is optimized to minimize the mass, resulting in a 29% weight reduction, compared to the initial design.
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45

Teixeira, José, Alexandra Gaspar, E. Manuela Garrido, Jorge Garrido et Fernanda Borges. « Hydroxycinnamic Acid Antioxidants : An Electrochemical Overview ». BioMed Research International 2013 (2013) : 1–11. http://dx.doi.org/10.1155/2013/251754.

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Hydroxycinnamic acids (such as ferulic, caffeic, sinapic, andp-coumaric acids) are a group of compounds highly abundant in food that may account for about one-third of the phenolic compounds in our diet. Hydroxycinnamic acids have gained an increasing interest in health because they are known to be potent antioxidants. These compounds have been described as chain-breaking antioxidants acting through radical scavenging activity, that is related to their hydrogen or electron donating capacity and to the ability to delocalize/stabilize the resulting phenoxyl radical within their structure. The free radical scavenger ability of antioxidants can be predicted from standard one-electron potentials. Thus, voltammetric methods have often been applied to characterize a diversity of natural and synthetic antioxidants essentially to get an insight into their mechanism and also as an important tool for the rational design of new and potent antioxidants. The structure-property-activity relationships (SPARs) correlations already established for this type of compounds suggest that redox potentials could be considered a good measure of antioxidant activity and an accurate guideline on the drug discovery and development process. Due to its magnitude in the antioxidant field, the electrochemistry of hydroxycinnamic acid-based antioxidants is reviewed highlighting the structure-property-activity relationships (SPARs) obtained so far.
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46

Leaman, Adrian. « Where Have All the Woodsmen Gone ? And Could Sustainable Timber Use in the UK Really Be Sustainable ? » Journal of Green Building 6, no 1 (1 février 2011) : 8–13. http://dx.doi.org/10.3992/jgb.6.1.8.

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We import the vast majority of our construction timber from abroad, some of it from illegally logged sources. Incredibly with our rural economy still in decline we now import even thatching spars from Poland. Meanwhile, many privately owned British woods are used only for tax avoidance, recreation, or firewood and are not producing quality timber. What is the way forward for United Kingdom forestry at a time when even our national forests are vulnerable.
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Rando, Thomas, et Danielle Fernholz. « MARITECH’s Shipbuilding Information Infrastructure ». Journal of Ship Production 16, no 02 (1 mai 2000) : 110–20. http://dx.doi.org/10.5957/jsp.2000.16.2.110.

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The goal of the Shipbuilding Information Infrastructure is to improve the accessibility and value of enterprise information for US shipbuilders. This promises notable benefits because the shipbuilding industry has significant information requirements. A ship may comprise more than a million parts, each of which must be managed through the many design, manufacture, test and logistics processes. The ability to share information across processes and organizations not only streamlines existing processes but offers the opportunity to identify new, improved processes. In order to strengthen the industry as a whole, the shipbuilding information infrastructure has to satisfy the following technical requirements:An information technology gap separates the large, medium and small shipyards.The information technology staffs at most shipyards are experts in shipbuilding process requirements but not in system-level computer technologies.Shipyard information systems must be reliable and maintainable yet often need to be customized to suit an individual shipyard. This paper describes how the SHIIP and SPARS projects have used a deliberate combination of component-based software, Internet protocols and a portable computing platform to satisfy these technical requirements. It describes how the SHIIP project has demonstrated that the Shipbuilding Information Infrastructure can be used for information sharing within a shipyard and how the SPARS project has demonstrated that the same infrastructure can be used for information sharing among shipyards, their partners and suppliers.
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В. Г. Вирченко. « Computer modular combinatorial-variational modeling of airplane structures elements ». MECHANICS OF GYROSCOPIC SYSTEMS, no 26 (23 décembre 2013) : 43–49. http://dx.doi.org/10.20535/0203-377126201330672.

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This paper considers the methodology of modular combinatorial-variational geometric modeling for technical objects on the example of automated shaping of some typical airplane structural elements.Stringers, beams, frames, spars, etc. were analyzed. Parametric geometric models of these objects were built. The models were combined with structural and parametric tools for effective computer-aided design.The proposed modular approach allows you to improve the performance of the creation processes of complex equipment. These simulation tools can successfully implement a comprehensive optimization of industrial products throughout their life cycle.It is possible to integrate computer structural-parametric geometric models stringers, beams, frames, spars, ribs, etc. with their design, technological and operational models in computer-aided design.The proposed approach is illustrated by computer model created in the environment of the software package SolidWorks. The curves of the second order in the rational parametric form were used for this purpose. Based on them, structurally-parametric solid models of the elements of the aircraft structure were built. Kinematic shaping techniques have been widely used in solving these tasks.Summary of the application of elaborated design techniques in other CAD/CAM/CAE systems to develop such parts and components of aircraft has been made.This applied research area automation design of complex modern techniques has good prospects for further development. However, it needs to carry out further intensive research of such sciences as geometry, design of aircraft, its aerodynamics and strength, manufacturing technology and exploitation to integrate successfully by means of computer information technologies.
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Esola, Shane, Brian Wisner, Prashanth Vanniamparambil, John Geriguis et Antonios Kontsos. « Part Qualification Methodology for Composite Aircraft Components Using Acoustic Emission Monitoring ». Applied Sciences 8, no 9 (29 août 2018) : 1490. http://dx.doi.org/10.3390/app8091490.

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The research presented in this article aims to demonstrate how acoustic emission (AE) monitoring can be implemented in an industrial setting to assist with part qualification, as mandated by related industry standards. The combined structural and nondestructive evaluation method presented departs from the traditional pass/fail criteria used for part qualification, and contributes toward a multi-dimensional assessment by taking advantage of AE data recorded during structural testing. To demonstrate the application of this method, 16 composite fixed-wing-aircraft spars were tested using a structural loading sequence designed around a manufacturer-specified design limit load (DLL). Increasing mechanical loads, expressed as a function of DLL were applied in a load-unload-reload pattern so that AE activity trends could be evaluated. In particular, the widely used Felicity ratio (FR) was calculated in conjunction with specific AE data post-processing, which allowed for spar test classification in terms of apparent damage behavior. To support such analysis and to identify damage critical regions in the spars, AE activity location analysis was also employed. Furthermore, recorded AE data were used to perform statistical analysis to demonstrate how AE datasets collected during part qualification could augment testing conclusions by providing additional information as compared to traditional strength testing frequently employed e.g., in the aerospace industry. In this context, AE data post-processing is presented in conjunction with ultimate strength information, and it is generally shown that the incorporation of AE monitoring is justified in such critical part qualification testing procedures.
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Brunson, Emily, Hannah Chandler, Gigi Gronvall, Sanjana Ravi, Tara Sell, Matthew Shearer et Monica Schoch-Spana. « The SPARS Pandemic 2025-2028 : A Futuristic Scenario to Facilitate Medical Countermeasure Communication ». Journal of International Crisis and Risk Communication Research 3, no 1 (9 mars 2020) : 71–102. http://dx.doi.org/10.30658/jicrcr.3.1.4.

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Effective communication about medical countermeasures—including drugs, devices and biologics—is often critical in emergency situations. Such communication, however, does not just happen. It must be planned and prepared for. One mechanism to develop communication strategies is through the use of prospective scenarios, which allow readers the opportunity to rehearse responses while also weighing the implications of their actions. This article describes the development of such a scenario: The SPARS Pandemic 2025-2028. Steps in this process included deciding on a timeframe, identifying likely critical uncertainties, and then using this framework to construct a storyline covering both the response and recovery phases of a fictional emergency event. Lessons learned from the scenario development and how the scenario can be used to improve communication are also discussed.
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