Several critical load cases during the aircraft design process result from atmospheric turbulence. Thus, rapidly performable and highly accurate dynamic response simulations are required to analyse a wide range of parameters. A method is proposed to predict dynamic loads on an elastically trimmed, large civil aircraft using computational fluid dynamics in conjunction with model reduction. A small-sized modal basis is computed by sampling the aerodynamic response at discrete frequencies and applying proper orthogonal decomposition. The linear operator of the Reynolds-averaged Navier-Stokes equations plus turbulence model is then projected onto the subspace spanned by this basis. The resulting reduced system is solved at an arbitrary number of frequencies to analyse responses to 1-cos gusts very efficiently. Lift coefficient and surface pressure distribution are compared with full-order, non-linear, unsteady time-marching simulations to verify the method. Overall, the reduced-order model predicts highly accurate global coefficients and surface loads at a fraction of the computational cost, which is an important step towards the aircraft loads process relying on computational fluid dynamics.

The development of glyphosate-resistant canola has provided improved weed-management options for growers, but crop tolerance to glyphosate may be inadequate at later growth stages. In this study, glyphosate-resistant canola 45H28 (RR) was used to determine the effects of glyphosate application timing on yield and yield components at several sites in western Canada. Canola received a single glyphosate applications at the two-leaf, six-leaf, bolting, and early bloom stages and sequential applications at the two-leaf + six-leaf, two-leaf + bolting, and two-leaf + early bloom stages. Contrasts were made between early vs. late, single vs. sequential, and on-label (two to six-leaf stage) vs. off-label (above six-leaf stage). In general, differences between application timings were observed for yield and yield components in 3 of 8 site-yr. Off-label applications of glyphosate (later than six-leaf) significantly decreased yield, seeds per pod, and increased thousand-seed weight and aborted pods in canola at the Lethbridge and St. Albert locations. Increased glyphosate translocation because of adequate, but not excessive, moisture to new growth may have suppressed new seed formation and encouraged pod abortion at the time of application in the 2010 and 2011 seasons. Results from this experiment demonstrate the importance of proper application timing of glyphosate on canola and can help better predict the effects of late applications.

Anatomical and electrophysiological studies have provided us with detailed information regarding the extent and topography of the primary (V1) and secondary (V2) visual areas in primates. The consensus about the V1 and V2 maps, however, is in sharp contrast with controversies regarding the organization of the cortical areas lying immediately rostral to V2. In this review, we address the contentious issue of the extent of the third visual area (V3). Specifically, we will argue for the existence of both ventral (V3v) and dorsal (V3d) segments of V3, which are located, respectively, adjacent to the anterior border of ventral and dorsal V2. V3v and V3d would together constitute a single functional area with a complete representation of both upper and lower visual hemifields. Another contentious issue is the organization of the parietal-occipital (PO) area, which also borders the rostral edge of the medial portion of dorsal V2. Different from V1, V2, and V3, which exhibit a topography based on the defined lines of isoeccentricity and isopolar representation, area PO only has a systematic representation of polar angles, with an emphasis on the peripheral visual field (isoeccentricity lines are not well defined). Based on the connectivity patterns of area PO with distinct cytochrome oxidase modules in V2, we propose a subdivision of the dorsal stream of visual information processing into lateral and medial domains. In this model, area PO constitutes the first processing instance of the dorsal-medial stream, coding for the full-field flow of visual cues during navigation. Finally, we compare our findings with those in other species of Old and New World monkeys and argue that larger animals, such as macaque and capuchin monkeys, have similar organizations of the areas rostral to V2, which is different from that in smaller New World monkeys.

We propose a numerical analysis of proper orthogonal decomposition (POD) model reductions in which a priori error estimates are expressed in terms of the projection errors that are controlled in the construction of POD bases. These error estimates are derived for generic parabolic evolution PDEs, including with non-linear Lipschitz right-hand sides, and for wave-like equations. A specific projection continuity norm appears in the estimates and – whereas a general uniform continuity bound seems out of reach – we prove that such a bound holds in a variety of Galerkin bases choices. Furthermore, we directly numerically assess this bound – and the effectiveness of the POD approach altogether – for test problems of the type considered in the numerical analysis, and also for more complex equations. Namely, the numerical assessment includes a parabolic equation with super-linear reaction terms, inspired from the FitzHugh-Nagumo electrophysiology model, and a 3D biomechanical heart model. This shows that the effectiveness established for the simpler models is also achieved in the reduced-order simulation of these highly complex systems.

We investigate the effectiveness of two extrapolation-based methods aiming to approximate the initial state required by an iterative solver in simulations of unsteady flow problems. The methods lead to about a ten-fold reduction in the iteration count while requiring only negligible computational overhead. They are particularly suitable for parallel computing since they are based almost exclusively on data stored locally on each processor. Performance has been evaluated in simulations of turbulent flow in a stenosed carotid artery and also in laminar flow in a very large domain containing the human intracranial arterial tree.

Les outils de CAO et de réalité virtuelle sont utiles pour simuler en temps réel la manipulation de pièces rigides, avec une détection des collisions. Les simulateurs temps réel industriels ont également besoin de prendre en compte les pièces déformables; cela suppose de pouvoir calculer en temps réel la déformée de pièces en contact. La méthode des éléments-finis ne peut pas fournir la déformée en temps réel pour un modèle à non-linéarités géométrique, matérielle et de contact. Une méthodologie composée de deux phases est ici proposée. Tout d’abord, une phase d’apprentissage consiste à réaliser une campagne de précalculs par éléments-finis représentative des besoins de la simulation en temps réel. Puis, la phase temps réel, non exposée dans cet article, exploite par interpolation la surface de réponse obtenue lors de cette campagne de précalculs. L’objectif de cet article, dans le cadre de la phase d’apprentissage, est de construire une surface de réponse réduite; pour cela des méthodes de réduction de modèle sont utilisées. Trois niveaux de réduction sont étudiés : une méthode adaptative avec base, la technique POD, et l’hyper réduction. L’écrasement d’un cylindre en caoutchouc sera étudié afin d’évaluer la performance de ces différentes méthodes.

L'objectif de ce travail est de construire par POD ("Proper Orthogonal Decomposition") des modèles d'ordre réduit permettant de reproduire de manière fiable la dynamique spatio-temporelle d'un écoulement décollé. L'intérêt croissant pour ces modèles réduits de dynamique s'explique par leur utilisation potentielle dans la résolution de problèmes d'optimisation sous contraintes de grande taille, rencontrés en contrôle d'écoulements. La démarche générale consiste à remplacer le modèle détaillé de l'écoulement (les équations de Navier-Stokes), par un modèle approché, plus rapide à résoudre et contenant les caractéristiques essentielles de la dynamique. La POD, optimale au sens de la reconstruction énergétique, permet d'approximer la dynamique de l'écoulement dans un sous-espace généré par un petit nombre de modes. Différentes méthodes de calibration sont ici développées afin d'améliorer la prédiction du modèle de dimension réduite, et ainsi rendre cette approche utilisable dans le cadre d'une problématique de contrôled'écoulements. Essentiellement, ces méthodes consistent à ajouter aux équations du modèle des termes supplémentaires calculés comme solutions d'un problème de minimisation sous contraintes.

L'objectif de cette étude est de minimiser, par rotationsinusoïdale, le coefficient de traînée moyen d'un cylindrecirculaire en régime laminaire. Une procédure d'optimisationcouplant modèle réduit par POD et méthode à région de confiance(TRPOD) est utilisée. Cette approche conduit à une réduction ducoefficient de traînée de 30 % pour un coût de calcul limité.

The anatomy of damaged and undamaged young stem, peduncle and young pods were examined from transverse sections in three varieties of cowpea in order to evaluate the anatomical basis of resistance to the pod borer Maruca testulalis.

While tissue development in the stem, peduncle and pods of the three varieties of cowpea were similar, the relative thickness of the various tissues were different in the order Vita-1>ICV-2>TVu 946. The smaller diameter and the relative abundance of strengthening tissues in the stem and peduncle of TVu 946, by limiting total ingestible biomass, might be restricting the damage to these organs by the pod borer.

Pod damage, on the other hand, was concentrated on the parenchymatous tissue of the pod wall lining and inter-seed spaces and the sizes of this tissue were also different among the varieties in the order Vita-1>ICV-2>TVu 946, the same order of susceptibility to attack by M. testulalis.

A direct approach to derive dependence properties among the hitting times of bivariate processes has been initiated by Ebrahimi (1987) and explored further by Ebrahimi and Ramallingam (1988). In this paper, new results are obtained for multivariate processes, which help us to identify positive and negative dependence structures among the hitting times of the processes. Applications of our theorems to reliability of systems are given.