A coupled model for flexible rotors

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New observations on diet of the South American two-striped forest-pitviper <i>Bothrops bilineatus smaragdinus</i> (Hoge, 1966)

The arboreal, nocturnal and widely distributed snake Bothrops bilineatus smaragdinus (Squamata, Viperidae) is known as a generalist whose diet items have rarely been identified to species level. In this work we report three new items for its diet: an adult frog Dendropsophus marmoratus (Anura, Hylidae), an adult lizard Thecadactylus solimoensis (Squamata, Phyllodactylidae), and an adult bat Carollia brevicauda (Chiroptera, Phyllostomidae), the latter being the first record of predation of a Chiropteran by this species.Asociación Herpetológica Argentin

Object-oriented modeling and simulation of the closed loop cardiovascular system by using SIMSCAPE

The modeling of physiological systems via mathematical equations reflects the calculation procedure more than the structure of the real system modeled, with the simulation environment SIMULINK™ being one of the best suited to this strategy. Nevertheless, object-oriented modeling is spreading in current simulation environments through the use of the individual components of the model and its interconnections to define the underlying dynamic equations. In this paper we describe the use of the SIMSCAPE™ simulation environment in the object-oriented modeling of the closed loop cardiovascular system. The described approach represents a valuable tool in the teaching of physiology for graduate medical students

New observations on diet of the South American two-striped forest-pitviper <i>Bothrops bilineatus smaragdinus</i> (Hoge, 1966)

The arboreal, nocturnal and widely distributed snake Bothrops bilineatus smaragdinus (Squamata, Viperidae) is known as a generalist whose diet items have rarely been identified to species level. In this work we report three new items for its diet: an adult frog Dendropsophus marmoratus (Anura, Hylidae), an adult lizard Thecadactylus solimoensis (Squamata, Phyllodactylidae), and an adult bat Carollia brevicauda (Chiroptera, Phyllostomidae), the latter being the first record of predation of a Chiropteran by this species.Asociación Herpetológica Argentin

New observations on diet of the South American two-striped forest-pitviper <i>Bothrops bilineatus smaragdinus</i> (Hoge, 1966)

The arboreal, nocturnal and widely distributed snake Bothrops bilineatus smaragdinus (Squamata, Viperidae) is known as a generalist whose diet items have rarely been identified to species level. In this work we report three new items for its diet: an adult frog Dendropsophus marmoratus (Anura, Hylidae), an adult lizard Thecadactylus solimoensis (Squamata, Phyllodactylidae), and an adult bat Carollia brevicauda (Chiroptera, Phyllostomidae), the latter being the first record of predation of a Chiropteran by this species.Asociación Herpetológica Argentin

Omecamtiv mecarbil in chronic heart failure with reduced ejection fraction, GALACTIC‐HF: baseline characteristics and comparison with contemporary clinical trials

Aims: The safety and efficacy of the novel selective cardiac myosin activator, omecamtiv mecarbil, in patients with heart failure with reduced ejection fraction (HFrEF) is tested in the Global Approach to Lowering Adverse Cardiac outcomes Through Improving Contractility in Heart Failure (GALACTIC‐HF) trial. Here we describe the baseline characteristics of participants in GALACTIC‐HF and how these compare with other contemporary trials. Methods and Results: Adults with established HFrEF, New York Heart Association functional class (NYHA) ≥ II, EF ≤35%, elevated natriuretic peptides and either current hospitalization for HF or history of hospitalization/ emergency department visit for HF within a year were randomized to either placebo or omecamtiv mecarbil (pharmacokinetic‐guided dosing: 25, 37.5 or 50 mg bid). 8256 patients [male (79%), non‐white (22%), mean age 65 years] were enrolled with a mean EF 27%, ischemic etiology in 54%, NYHA II 53% and III/IV 47%, and median NT‐proBNP 1971 pg/mL. HF therapies at baseline were among the most effectively employed in contemporary HF trials. GALACTIC‐HF randomized patients representative of recent HF registries and trials with substantial numbers of patients also having characteristics understudied in previous trials including more from North America (n = 1386), enrolled as inpatients (n = 2084), systolic blood pressure &lt; 100 mmHg (n = 1127), estimated glomerular filtration rate &lt; 30 mL/min/1.73 m2 (n = 528), and treated with sacubitril‐valsartan at baseline (n = 1594). Conclusions: GALACTIC‐HF enrolled a well‐treated, high‐risk population from both inpatient and outpatient settings, which will provide a definitive evaluation of the efficacy and safety of this novel therapy, as well as informing its potential future implementation

Modeling of flexible rotor blades

Historiquement, les rotors ont été développés pour la propulsion et la génération d’énergie. Pendant des années, grands efforts de recherche ont été fournis pour les éoliennes et les hélicoptères. Or, des nouvelles applications comme les drones nécessitent une recherche plus approfondie. La flexibilité du rotor et les conditions de fonctionnement particulières constituent un défi pour l'optimisation de leur design. Dans cette thèse, on propose un modèle fluide-structure qui prend en compte la flexibilité des pales dans des conditions de fonctionnement non-conventionnelles. Le modèle est suffisamment simple et robuste pour la réalisation d'études paramétriques extensives. Il comprend des modèles pour le sillage et la structure flexible du rotor. Deux modèles du sillage sont considérés: un modèle classique de Joukowski et un modèle généralisé. Dans le modèle classique, deux vortex sont émis par pale, l’un sur la pointe et l’autre sur l’axe. Dans le modèle généralisé, le tourbillon axial est décalé par rapport au centre. Une analyse de stabilité est réalisée pour les solutions dérivées avec le modèle classique. La nature convective/absolue de l’instabilité est étudiée pour différentes conditions de fonctionnement. Les solutions stationnaires du sillage sont utilisées pour calculer le champ de vitesse induit dans le plan rotor. Ainsi, à partir de la loi de Kutta-Joukowski et de la théorie des éléments de pale (BET), on peux déterminer les charges aérodynamiques exercés sur les pales. Le couplage du rotor avec son sillage est alors implémenté pour une configuration rigide. Finalement, la flexibilité de la pale est prise en compte à l’aide d’un modèle de poutre élastiqueRotors have been historically developed for harvesting and propulsion. For wind turbines and helicopters, decades of research have been done to optimize their design. For recent applications, such as drones, no such a research effort has been made. The high flexibility of the rotor and the different operational conditions still constitute challenging issues for their design. In this work, a coupled fluid-structure model is proposed, taking into account the flexibility of the blades in non-conventional operational conditions.The model is sufficiently simple and robust to permit extensive parameter studies. It includes a model for the wake, a model for the flexible rotor structure and the coupling. Two different wake models are considered: a classical Joukowski model, where two vortices are emitted per blade, one at the tip and one at the axis, and a generalized Joukowski model where the axial vortex is replaced by a hub vortex emitted away from the center. A stability analysis of the solutions derived with the classical Joukowski model is performed. The convective/absolute nature of the instability is analysed for various operational conditions.Stationary wake solutions are used to calculate the flow in the rotor plane. Kutta-Joukowski law and Blade Element Theory are applied to obtain the aerodynamic loads exerted on the blades. The full coupling of the rotor with its wake is first implemented for a rigid configuration. Coupled solutions are obtained for different rotors and compared to experimental and numerical data published in the literature. Finally, blade flexibility is considered using a rod model for the blad

Rotor Generated Vortices: Structure and Stability

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Generalized helical vortex structures

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GEOMETRY AND STABILITY OF THE VORTICES GENERATED BY A ROTOR

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