A method to the madness: Ontogenetic changes in the hydrostatic properties of Didymoceras (Nostoceratidae: Ammonoidea)

Paleobiology ◽  
2020 ◽  
Vol 46 (2) ◽  
pp. 237-258 ◽  
Author(s):  
David J. Peterman ◽  
Margaret M. Yacobucci ◽  
Neal L. Larson ◽  
Charles Ciampaglio ◽  
Tom Linn
Keyword(s):  
Vertical Axis ◽  
3D Models ◽  
Juvenile Stage ◽  
Ontogenetic Changes ◽  
Neutral Buoyancy ◽  
Juvenile Dispersal ◽  
Directional Movement ◽  
Stability Change ◽  
Upward Direction ◽  
Two Stages

AbstractThe seemingly aberrant coiling of heteromorphic ammonoids suggests that they underwent more significant changes in hydrostatic properties throughout ontogeny than their planispiral counterparts. Such changes may have been responses to different selective pressures at different life stages. The hydrostatic properties of three species of Didymoceras (D. stevensoni, D. nebrascense, and D. cheyennense) were investigated by creating virtual 3D models at several stages during growth. These models were used to compute the conditions for neutral buoyancy, hydrostatic stability, orientation during life, and thrust angles (efficiency of directional movement). These properties suggest that Didymoceras and similar heteromorphs lived low-energy lifestyles with the ability to hover above the seafloor. The resultant static orientations yielded a downward-facing aperture in the hatchling and a horizontally facing aperture throughout most of the juvenile stage, before terminating in an upward direction at maturity. Relatively high hydrostatic stabilities would not have permitted the orientation of Didymoceras to be considerably modified with active locomotion. During the helical phase, Didymoceras would have been poorly suited for horizontal movement, yet equipped to pirouette about the vertical axis. Two stages throughout growth, however, would have enhanced lateral mobility: a juvenile stage just after the formation of the first bend in the shell and the terminal stage after completion of the U-shaped hook. These two more mobile phases in ontogeny may have improved juvenile dispersal potential and mate acquisition during adulthood, respectively. In general, life orientation and hydrostatic stability change more wildly for these aberrantly coiled ammonoids than their planispiral counterparts.

scholarly journals The balancing act of Nipponites mirabilis (Nostoceratidae, Ammonoidea): managing hydrostatics during a complex ontogenetic trajectory

2020 ◽  
Author(s):  
David J. Peterman ◽  
Tomoyuki Mikami ◽  
Shinya Inoue
Keyword(s):  
Late Cretaceous ◽  
Vertical Axis ◽  
3D Models ◽  
Low Energy ◽  
Soft Body ◽  
Neutral Buoyancy ◽  
Ontogenetic Stages ◽  
Ontogenetic Trajectory ◽  
Mode Of Life

AbstractNipponites is a heteromorph ammonoid with a complex and unique morphology that obscures its mode of life and ethology. The seemingly aberrant shell of this Late Cretaceous nostoceratid seems deleterious. However, hydrostatic simulations suggest that this morphology confers several advantages for exploiting a quasi-planktic mode of life. Virtual, 3D models of Nipponites mirabilis were used to compute various hydrostatic properties through 14 ontogenetic stages. At each stage, Nipponites had the capacity for neutral buoyancy and was not restricted to the seafloor. Throughout ontogeny, horizontally facing to upwardly facing soft body orientations were preferred. These orientations were aided by the obliquity of the shell’s ribs, which were parallel to former positions of the aperture during life. Static orientations were somewhat fixed, inferred by stability values that are slightly higher than extant Nautilus. The initial open-whorled, planispiral phase is well suited to horizontal backwards movement with little rocking. Nipponites then deviates from this coiling pattern with a series of alternating U-shaped bends in the shell. This modification allows for proficient rotation about the vertical axis, while possibly maintaining the option for horizontal backwards movement by redirecting its hyponome. These particular hydrostatic properties likely result in a tradeoff between hydrodynamic streamlining, suggesting that Nipponites assumed a low energy lifestyle of slowly pirouetting in search for planktic prey. Each computed hydrostatic property influences the others in some way, suggesting that Nipponites maintained a delicate hydrostatic balancing act throughout its ontogeny in order to facilitate this mode of life.

Aerodynamic and aeroacoustic performance investigations on modified H-rotor Darrieus wind turbine

2021 ◽  
pp. 0309524X2110039
Author(s):  
Amgad Dessoky ◽  
Thorsten Lutz ◽  
Ewald Krämer
Keyword(s):  
Wind Turbine ◽  
High Speed ◽  
Cfd Simulation ◽  
Vertical Axis ◽  
3D Models ◽  
Power Coefficient ◽  
Design Parameters ◽  
Second Phase ◽  
Vertical Axis Wind Turbine ◽  
Guide Vanes

The present paper investigates the aerodynamic and aeroacoustic characteristics of the H-rotor Darrieus vertical axis wind turbine (VAWT) combined with very promising energy conversion and steering technology; a fixed guide-vanes. The main scope of the current work is to enhance the aerodynamic performance and assess the noise production accomplished with such enhancement. The studies are carried out in two phases; the first phase is a parametric 2D CFD simulation employing the unsteady Reynolds-averaged Navier-Stokes (URANS) approach to optimize the design parameters of the guide-vanes. The second phase is a 3D CFD simulation of the full turbine using a higher-order numerical scheme and a hybrid RANS/LES (DDES) method. The guide-vanes show a superior power augmentation, about 42% increase in the power coefficient at λ = 2.75, with a slightly noisy operation and completely change the signal directivity. A remarkable difference in power coefficient is observed between 2D and 3D models at the high-speed ratios stems from the 3D effect. As a result, a 3D simulation of the capped Darrieus turbine is carried out, and then a noise assessment of such configuration is assessed. The results show a 20% increase in power coefficient by using the cap, without significant change in the noise signal.

scholarly journals Decapodid and early juvenile development in the protandrous shrimp Campylonotus vagans (Crustacea: Decapoda: Caridea), with notes on larval morphology

2003 ◽  
Vol 83 (1) ◽  
pp. 103-109 ◽  
Author(s):  
Sven Thatje ◽  
Gustavo A. Lovrich
Keyword(s):  
Low Temperatures ◽  
Juvenile Stage ◽  
Tierra Del Fuego ◽  
Caridean Shrimp ◽  
Early Juvenile ◽  
Morphological Variations ◽  
Sexual Determination ◽  
Juvenile Stages ◽  
Two Stages ◽  
Juvenile Development

The decapodid and first two juvenile stages of the caridean shrimp Campylonotus vagans from the Subantarctic Beagle Channel (Tierra del Fuego, Argentina) are described and illustrated in detail. The complete larval and early juvenile development of this species from rearings under controlled laboratory conditions were analysed. Zoeal morphology in two stages of an abbreviated development was identical to a description from plankton and hatched larvae of a previous work, and therefore we only compare and discuss slight morphological variations in this study. The first juvenile is large and already resembles some features of adults, lacking all ventral rostral and the fourth dorsal rostral spine only which appears in the following stage, and the second pereiopod not yet being as predominant as in adults. Sexual determination is not yet possible up to the described second juvenile stage. The abbreviated larval development in a Subantarctic shrimp species is discussed as an adaptation to low temperatures and pronounced seasonality.

scholarly journals CFD Investigation of A New Elliptical-Bladed Multistage Savonius Rotors

2020 ◽  
Vol 9 (3) ◽  
pp. 383-392
Author(s):  
Khalid Mrigua ◽  
Abdelghani Toumi ◽  
Mounia Zemamou ◽  
Bader Ouhmmou ◽  
Yahya Lahlou ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Low Wind Speed ◽  
Coefficient Increase ◽  
Savonius Wind Turbine ◽  
Low Efficiency ◽  
Two Stages

The Savonius-conventional wind turbine is a class of wind turbines designed with a vertical axis. It has a good starting capacity and   an insensitivity to wind direction. It works relatively at low wind speed in an easy installation. Savonius wind turbine faces major drawbacks, including some of the low efficiency and high negative torque created by the returning blade. Many attempts have been undertaken to optimize the blade’s shape to increase the performance of these wind turbines. The vertical axis is still under development. The elliptical-blades with a cut angle equal 47.50° have recently shown enhanced performance. In this study, we investigate the effect of Elliptical-bladed multistage Savonius Rotors (rotor aspect ratio, stage aspect ratio) on the performance by means of numerical simulation. The results obtained by comparison of one, two, and three-stage rotors indicate that the maximum power coefficient increase with a number of the stages (for the rotors with similar RAR of 0.7). Moreover, for the rotors with similar SAR of 0.7, the two stages have the highest performance than others.©2020. CBIORE-IJRED. All rights reserved

scholarly journals Numerical and Experimental Efficiency Evaluation of a Counter-Rotating Vertical Axis Wind Turbine

2018 ◽  
Vol 8 (4) ◽  
pp. 3282-3286
Author(s):  
I. Malael ◽  
V. Dragan
Keyword(s):  
Wind Turbine ◽  
Free Stream ◽  
Experimental Tests ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine ◽  
Ansys Fluent ◽  
Sliding Mesh ◽  
Momentum Coefficient ◽  
Fluent Software ◽  
Two Stages

This paper investigates the concept of a concentric counter-rotating vertical axis wind turbine (VAWT), consisting of a two stage vertical H-type turbine with three blades on each stage. The model has an inner and an outer stage, rotating in opposition to each other. Both numerical and experimental tests have been performed in order to validate this new concept. Numerical analysis is based on the use of 2.5-dimensional, unsteady simulations using a DOF type of analysis which allows for the two stages to self-adjust their rotation speed. Sliding mesh conformal interfaces are defined between these subdomains to minimize numerical artifacts such as artificial relations or entropy changes. Fully turbulent URANS were carried out in Ansys Fluent software. One key outcome was the momentum coefficient for each stage at different tip wind speed values. Another, more qualitative, outcome is the analysis of vortex shedding, impingement and overall interaction between the stages at different positions and scenarios. Ultimately, the numerical results have been validated using a scaled experimental device which was analyzed in the wind tunnel at different free stream speeds.

scholarly journals A novel length back-calculation approach accounting for ontogenetic changes in the fish length – otolith size relationship during the early life of sprat (Sprattus sprattus)

2012 ◽  
Vol 69 (7) ◽  
pp. 1214-1229 ◽  
Author(s):  
Claudia C. Günther ◽  
Axel Temming ◽  
Hannes Baumann ◽  
Bastian Huwer ◽  
Christian Möllmann ◽  
...  
Keyword(s):  
Calculation Method ◽  
Juvenile Stage ◽  
Growth Potential ◽  
Fish Length ◽  
Ontogenetic Changes ◽  
Sprattus Sprattus ◽  
Early Juvenile ◽  
Length Growth ◽  
Early Juvenile Stage ◽  
Back Calculation

An individual-based length back-calculation method was developed for juvenile Baltic sprat ( Sprattus sprattus ), accounting for ontogenetic changes in the relationship between fish length and otolith length. In sprat, metamorphosis from larvae to juveniles is characterized by the coincidence of low length growth, strong growth in body height, and maximal otolith growth. Consequently, the method identifies a point of metamorphosis for an individual as the otolith radius at maximum increment widths. By incorporating this information in our back-calculation method, estimated length growth for the early larval stage was more than 60% higher compared with the result of the biological intercept model. After minimal length growth during metamorphosis, we found the highest increase in length during the early juvenile stage. We thus located the strongest growth potential in the early juvenile stage, which is supposed to be critical in determining recruitment strength in Baltic sprat.

Floating the Vrancea slab and tectonic reconstruction of the collapse of the PalaeoPannonian Basin

2021 ◽  
Author(s):  
Jack Muston ◽  
Wim Spakman ◽  
Gordon Lister
Keyword(s):  
Large Scale ◽  
Pannonian Basin ◽  
Vertical Axis ◽  
3D Models ◽  
Fault System ◽  
Slab Geometry ◽  
Lower Velocity ◽  
Tomographic Images ◽  
Model Interpretation ◽  
Tectonic Reconstruction

<p>Here we present the first 4D tectonic reconstruction that models the Vrancea slablet and incorporates the floated slab as a constraint on the magnitude of slab rollback during collapse of the Palaeo-Pannonian Basin. Seismic tomographic images provide insight into the geometry and tectonic history of subducted slabs. High velocity anomalies can be interpreted as ‘cold’ lithosphere penetrating ‘warmer’ lower velocity asthenosphere, and 3D models created using the <em>SKUA-GOCAD</em> modelling software. Combined with information from the 3D distribution of earthquake hypocentres, we thereby obtain a simple approximation to slab geometry beneath the Vrancea region. The resultant DXF was imported into the <em>Pplates</em> tectonic reconstruction software, and floated back to the Earth’s surface. The method utilised assumes no significant deformation (stretching, buckling, folding, shortening) during or after subduction, so that the obtained geometry estimates the pre-subduction configuration. The resultant floated slab is then incorporated as a constraint on 2D + time tectonic reconstructions. We apply a double-saloon-door rollback model, which involves propagation of a slab tear along the mid-Hungarian lineament. Each saloon-door rolls back independently of the other and this leads to two epochs of extension. AlPaCa is ‘pulled’ eastwards and rotated counter-clockwise as the western saloon-door rolls back. The Tisza-Dacia unit is then ‘pulled’ eastward, and rotated, but in a clockwise sense as the eastern saloon-door rolls back. Once the subduction hinge reached the East European Platform, the slab was left hanging. Gravitational forces then drove slab-boudinage and detachment in a similar fashion as occurs today beneath the Hindu Kush. This model explains the large opposing-sense vertical-axis rotations that occurred during convergence of the AlPaCa and Tisza-Dacia terranes. The zipper fault model rotates the microplates without requiring large-scale thrusting. Interpretation of the Mid-Hungarian lineament as a zipper-fault system is also consistent with the geodynamic effects expected because of tearing in a subducting plate leading to a double-saloon-door rollback. The vertical extent of the slab is roughly 300 km, which only fills half of the basin, consistent with the double-saloon-door roll-back model interpretation.</p>

Thermo-Mechanical Numerical Analysis in Steel Plates Butt Welded

2014 ◽  
Author(s):  
Manuel Martinez ◽  
Marco Gonzalez ◽  
Antonio Barragan
Keyword(s):  
Residual Stress ◽  
Thick Plate ◽  
Transient State ◽  
3D Models ◽  
Steel Plates ◽  
Welded Steel ◽  
Structural Part ◽  
Structural Responses ◽  
Two Stages ◽  
2D And 3D

In this work, 2D and 3D Finite Element models to simulate the temperature distribution and residual stress in butt-welded steel plates with the aid of computer simulation, using the commercial software Abaqus®, are developed. The work is carried out in two stages: 1) An analysis of heat transfer in transient state regardless of the structural part is performed, and 2) Thermal and structural responses are sequentially coupled in a thermo-mechanical process simulation in order to determine the final residual stresses induced during progressive heating and subsequent cooling. The results show that for 2D and 3D models the residual stress distribution for relatively thick plate welding can be characterized by a state of stresses plane, dominated by longitudinal stresses. The main difference between both models occurs for transverse stress σY where the values for 3D are significantly greater than for 2D.

scholarly journals DIGITALIZACIÓN DE FORMAS DE LA NATURALEZA COMO RECURSO MORFOLÓGICO

2020 ◽  
pp. 133-149
Author(s):  
Santiago Javier Santamaría-Bedón
Keyword(s):  
Golden Ratio ◽  
Three Dimensional ◽  
Fibonacci Sequence ◽  
Vertical Axis ◽  
3D Models ◽  
Morphological Variations ◽  
Geometric Patterns ◽  
Golden Angle ◽  
Dense Point ◽  
Photo Alignment

La biomimética imita los procesos naturales para plantear posibles soluciones a problemas humanos y ha sido aplicado por varias profesiones, convirtiéndose en una práctica recurrente para adoptar nuevas morfologías o principios funcionales. Leonardo de Pisa empleó estos fenómenos y desarrolló una serie matemática llamada sucesión de Fibonacci, dando lugar posteriormente a la proporción áurea. Estos descubrimientos matemáticos se manifiestan en forma concurrente en patrones geométricos de los procesos y estructuras de la naturaleza como en la distribución de hojas en las plantas. El objetivo de este artículo es proponer recursos formales procedentes de la aplicación de la biomimética de manera superficial/reductiva, que adopta la morfología de la planta Sempervivum tectorum L. para futuras soluciones formales y funcionales del ámbito del diseño. Para ello, se aplica la fotogrametría como técnica para capturar información bidimensional mediante fotografías y convertirlas en información tridimensional, obteniendo un modelo idéntico al original. La digitalización del elemento natural cumple con la siguiente metodología: preparación del entorno, toma de datos, alineación de fotografías, creación de nube de puntos densa, creación de malla y la textura. Posteriormente se realiza la construcción de modelos 3D, siguiendo el recorrido helicoidal digitalizado. Esta trayectoria crea un patrón en forma de hélice que se repite en sentido radial, tomando como referencia el eje vertical, de esta manera se crea un vórtice en la corona del sólido. A partir de esta estructura se realiza variaciones morfológicas, respetando la dirección de la hélice matriz. Palabras clave: Morfología, fotogrametría, ángulo de oro, sucesión de Fibonacci, diseño. AbstractBiomimetics mimics natural processes to propose possible solutions to human problems and has been applied by various professions, making it a recurring practice to adopt new morphologies or functional principles. Leonardo of Pisa used these phenomena and developed a mathematical series called the Fibonacci sequence, later giving rise to the golden ratio. These mathematical discoveries are manifested concurrently in geometric patterns of the processes and structures of nature as in the distribution of leaves in plants. The objective of this article was to propose formal resources from the application of biomimetics in a superficial / reductive way, which adopts the morphology of the Sempervivum tectorum L. plant for future formal and functional solutions in the field of design. To this end, photogrammetry was applied as a technique to capture two-dimensional information through photographs and convert them into three-dimensional information, obtaining a model identical to the original. The digitization of the natural element complied with the following methodology: environment preparation, data collection, photo alignment, dense point cloud creation, mesh and texture creation. Subsequently, the construction of 3D models is carried out, following the digitized helical path. This path created a helix-shaped pattern that was repeated radially, taking the vertical axis as a reference, thus creating a vortex in the crown of the solid. Morphological variations were made from this structure, respecting the direction of the parent helix. Keywords: Morphology, digital photogrammetry, golden angle, Fibonacci sequence, design.

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