scholarly journals Relations between morphology, buoyancy and energetics of requiem sharks

2016 ◽  
Vol 3 (10) ◽  
pp. 160406 ◽  
Author(s):  
Gil Iosilevskii ◽  
Yannis P. Papastamatiou
Keyword(s):  
Body Temperature ◽  
Negative Selection ◽  
Swimming Performance ◽  
Ontogenetic Changes ◽  
Cost Of Transport ◽  
Pectoral Fins ◽  
Confined Spaces ◽  
Reef Sharks ◽  
The Cost ◽  
Derivatives Of

Sharks have a distinctive shape that remained practically unchanged through hundreds of millions of years of evolution. Nonetheless, there are variations of this shape that vary between and within species. We attempt to explain these variations by examining the partial derivatives of the cost of transport of a generic shark with respect to buoyancy, span and chord of its pectoral fins, length, girth and body temperature. Our analysis predicts an intricate relation between these parameters, suggesting that ectothermic species residing in cooler temperatures must either have longer pectoral fins and/or be more buoyant in order to maintain swimming performance. It also suggests that, in general, the buoyancy must increase with size, and therefore, there must be ontogenetic changes within a species, with individuals getting more buoyant as they grow. Pelagic species seem to have near optimally sized fins (which minimize the cost of transport), but the majority of reef sharks could have reduced the cost of transport by increasing the size of their fins. The fact that they do not implies negative selection, probably owing to decreased manoeuvrability in confined spaces (e.g. foraging on a reef).

scholarly journals The rising cost of warming waters: effects of temperature on the cost of swimming in fishes

2011 ◽  
Vol 8 (2) ◽  
pp. 266-269 ◽  
Author(s):  
Andrew M. Hein ◽  
Katrina J. Keirsted
Keyword(s):  
Water Temperature ◽  
Fish Species ◽  
Global Climate ◽  
Swimming Performance ◽  
Metabolic Cost ◽  
Quantitative Model ◽  
The Body ◽  
Energetic Cost ◽  
Cost Of Transport ◽  
The Cost

Understanding the effects of water temperature on the swimming performance of fishes is central in understanding how fish species will respond to global climate change. Metabolic cost of transport (COT)—a measure of the energy required to swim a given distance—is a key performance parameter linked to many aspects of fish life history. We develop a quantitative model to predict the effect of water temperature on COT. The model facilitates comparisons among species that differ in body size by incorporating the body mass-dependence of COT. Data from 22 fish species support the temperature and mass dependencies of COT predicted by our model, and demonstrate that modest differences in water temperature can result in substantial differences in the energetic cost of swimming.

Thermal constraints on swimming performance and escape response of northern water snakes (Nerodia sipedon)

1992 ◽  
Vol 70 (1) ◽  
pp. 94-98 ◽  
Author(s):  
Patrick J. Weatherhead ◽  
Ian C. Robertson
Keyword(s):  
Body Temperature ◽  
Water Temperature ◽  
Swimming Speed ◽  
Escape Response ◽  
Swimming Performance ◽  
Nerodia Sipedon ◽  
Water Snake ◽  
Northern Water Snakes ◽  
The Cost ◽  
Water Snakes

We examined the influence of body temperature on swimming speed of northern water snakes (Nerodia sipedon) and determined how variation in water temperature influenced their escape response. In a laboratory experiment, swimming speed increased as a function of water temperature and body size. Swimming speed was less thermally dependent at temperatures approximating the snakes' normal range of activity, suggesting that selection has favoured increased performance breadth at this range. In the field, basking snakes retreated to water when approached. Despite a decrease in swimming speed at lower temperatures, and the cost associated with reduced metabolic rate due to loss of body temperature, however, flight distances were independent of water temperature. We found that basking snakes retreated to water sooner when perched at lower heights, possibly indicating that N. sipedon are more vulnerable to predators when on low perches. Predicting water snake escape behaviour may require not only knowledge of variation both among snakes and in their environment, but also a better understanding of the interaction between the snakes and their natural predators.

scholarly journals Swimming Through Parameter Subspaces of a Simple Anguilliform Swimmer

2020 ◽  
Vol 60 (5) ◽  
pp. 1221-1235 ◽  
Author(s):  
Nicholas A Battista
Keyword(s):  
Immersed Boundary Method ◽  
Swimming Performance ◽  
Immersed Boundary ◽  
Cost Of Transport ◽  
Structure Interaction ◽  
Numerous Model ◽  
Robust Parameter ◽  
And Performance ◽  
The Cost ◽  
Fluid Interaction

Synopsis Computational scientists have investigated swimming performance across a multitude of different systems for decades. Most models depend on numerous model input parameters and performance is sensitive to those parameters. In this article, parameter subspaces are qualitatively identified in which there exists enhanced swimming performance for an idealized, simple swimming model that resembles a Caenorhabditis elegans, an organism that exhibits an anguilliform mode of locomotion. The computational model uses the immersed boundary method to solve the fluid-interaction system. The 1D swimmer propagates itself forward by dynamically changing its preferred body curvature. Observations indicate that the swimmer’s performance appears more sensitive to fluid scale and stroke frequency, rather than variations in the velocity and acceleration of either its upstroke or downstroke as a whole. Pareto-like optimal fronts were also identified within the data for the cost of transport and swimming speed. While this methodology allows one to locate robust parameter subspaces for desired performance in a straight-forward manner, it comes at the cost of simulating orders of magnitude more simulations than traditional fluid–structure interaction studies.

scholarly journals The performance of a flapping foil for a self-propelled fishlike body

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Damiano Paniccia ◽  
Luca Padovani ◽  
Giorgio Graziani ◽  
Renzo Piva
Keyword(s):  
Swimming Performance ◽  
Real Life ◽  
Minimum Cost ◽  
The Body ◽  
Cost Of Transport ◽  
Locomotion Speed ◽  
Optimal Efficiency ◽  
The One ◽  
The Cost ◽  
Flapping Foils

AbstractSeveral fish species propel by oscillating the tail, while the remaining part of the body essentially contributes to the overall drag. Since in this case thrust and drag are in a way separable, most attention was focused on the study of propulsive efficiency for flapping foils under a prescribed stream. We claim here that the swimming performance should be evaluated, as for undulating fish whose drag and thrust are severely entangled, by turning to self-propelled locomotion to find the proper speed and the cost of transport for a given fishlike body. As a major finding, the minimum value of this quantity corresponds to a locomotion speed in a range markedly different from the one associated with the optimal efficiency of the propulsor. A large value of the feathering parameter characterizes the minimum cost of transport while the optimal efficiency is related to a large effective angle of attack. We adopt here a simple two-dimensional model for both inviscid and viscous flows to proof the above statements in the case of self-propelled axial swimming. We believe that such an easy approach gives a way for a direct extension to fully free swimming and to real-life configurations.

Pump or coast: the role of resonance and passive energy recapture in medusan swimming performance

2019 ◽  
Vol 863 ◽  
pp. 1031-1061 ◽  
Author(s):  
Alexander P. Hoover ◽  
Antonio J. Porras ◽  
Laura A. Miller
Keyword(s):  
Immersed Boundary Method ◽  
Significant Contribution ◽  
Swimming Performance ◽  
Three Dimensional ◽  
Vortex Rings ◽  
Immersed Boundary ◽  
Cost Of Transport ◽  
The Cost ◽  
Inertial Regime

Diverse organisms that swim and fly in the inertial regime use the flapping or pumping of flexible appendages and cavities to propel themselves through a fluid. It has long been postulated that the speed and efficiency of locomotion are optimized by oscillating these appendages at their frequency of free vibration. In jellyfish swimming, a significant contribution to locomotory efficiency has been attributed to the effects passive energy recapture, whereby the bell is passively propelled through the fluid through its interaction with stopping vortex rings formed during each expansion of the bell. In this paper, we investigate the interplay between resonance and passive energy recapture using a three-dimensional implementation of the immersed boundary method to solve the fluid–structure interaction of an elastic oblate jellyfish bell propelling itself through a viscous fluid. The motion is generated through a fixed duration application of active tension to the bell margin, which mimics the action of the coronal swimming muscles. The pulsing frequency is then varied by altering the length of time between the application of applied tension. We find that the swimming speed is maximized when the bell is driven at its resonant frequency. However, the cost of transport is maximized by driving the bell at lower frequencies whereby the jellyfish passively coasts between active contractions through its interaction with the stopping vortex ring. Furthermore, the thrust generated by passive energy recapture was found to be dependent on the elastic properties of the jellyfish bell.

The Metabolic Cost of Swimming in Ducks

1970 ◽  
Vol 53 (3) ◽  
pp. 763-777 ◽  
Author(s):  
HENRY D. PRANGE ◽  
KNUT SCHMIDT-NIELSEN
Keyword(s):  
Oxygen Consumption ◽  
Swimming Speed ◽  
Swimming Performance ◽  
Water Channel ◽  
Minimum Cost ◽  
Metabolic Cost ◽  
Power Input ◽  
Cost Of Transport ◽  
Overall Efficiency ◽  
The Cost

1. The metabolic cost of swimming was studied in mallard ducks (Anas platyrhynchos) which had been trained to swim steadily in a variable-speed water channel. 2. At speeds of from 0.35 to 0.50 m/sec the oxygen consumption remained relatively constant at approximately 2.2 times the resting level. At speeds of 0.55 m/sec and higher the oxygen consumption increased rapidly and reached 4.1 times resting at the maximum sustainable speed of 0.70 m/sec. 3. The maximum sustainable swimming speed of the ducks coincided with the limit predicted from hydrodynamic considerations of the water resistance of a displacement-hulled ship of the same hull length as a duck (0.33 m). 4. The cost of transport (metabolic rate/speed) reached a minimum of 5.77 kcal/kg km at a swimming speed of 0.50 m/sec. Ducks swimming freely on a pond were observed to swim at the speed calculated in experimental trials to give minimum cost of transport. 5. Drag measurements made with model ducks indicated a maximum overall efficiency (power output/power input) for the swimming ducks of about 5%. Ships typically have maximum efficiencies of 20-30%. Because of the difficulty in delimiting the cost of swimming activity alone from the other bodily functions of the duck, overall efficiency may present an incorrect description of the swimming performance of the duck relative to that of a ship. An hydrodynamic parameter such as speed/length ratio [speed/(hull length)½] whereby a duck excels conventional ships may present a more appropriate comparison.

scholarly journals An Analytic and Numerical Investigation of a Differential Game

Axioms ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 66
Author(s):  
Aviv Gibali ◽  
Oleg Kelis
Keyword(s):  
Differential Game ◽  
Equation Approach ◽  
Linear Quadratic ◽  
Control Cost ◽  
Dual Representation ◽  
Cost Functional ◽  
Variational Derivatives ◽  
Zero Sum ◽  
The Cost ◽  
Derivatives Of

In this paper we present an appropriate singular, zero-sum, linear-quadratic differential game. One of the main features of this game is that the weight matrix of the minimizer’s control cost in the cost functional is singular. Due to this singularity, the game cannot be solved either by applying the Isaacs MinMax principle, or the Bellman–Isaacs equation approach. As an application, we introduced an interception differential game with an appropriate regularized cost functional and developed an appropriate dual representation. By developing the variational derivatives of this regularized cost functional, we apply Popov’s approximation method and show how the numerical results coincide with the dual representation.

scholarly journals Active cutaneous warming systems to prevent intraoperative hypothermia: a systematic review

2012 ◽  
Vol 20 (1) ◽  
pp. 183-191 ◽  
Author(s):  
Vanessa de Brito Poveda ◽  
Edson Zangiacomi Martinez ◽  
Cristina Maria Galvão
Keyword(s):  
Systematic Review ◽  
Decision Making ◽  
Body Temperature ◽  
Cost Benefit ◽  
Controlled Trials ◽  
Decision Making Process ◽  
Circulating Water ◽  
Randomized Controlled ◽  
Intraoperative Hypothermia ◽  
The Cost

This study analyzed the evidence available in the literature concerning the effectiveness of different active cutaneous warming systems to prevent intraoperative hypothermia. This is a systematic review with primary studies found in the following databases: CINAHL, EMBASE, Cochrane Register of Controlled Trials and Medline. The sample comprised 23 randomized controlled trials. There is evidence in the literature indicating that the circulating water garment system is the most effective in maintaining patient body temperature. These results can support nurses in the decision-making process concerning the implementation of effective measures to maintain normothermia, though the decision of health services concerning which system to choose should also take into account its cost-benefit status given the cost related to the acquisition of such systems.

New Evolutionary Algorithm Based on 2-Opt Local Search to Solve the Vehicle Routing Problem with Private Fleet and Common Carrier

2012 ◽  
pp. 125-148
Author(s):  
Jalel Euchi ◽  
Habib Chabchoub ◽  
Adnan Yassine
Keyword(s):  
Local Search ◽  
Evolutionary Algorithm ◽  
Vehicle Routing ◽  
Cost Savings ◽  
Alternative Mode ◽  
Cost Of Transport ◽  
Routing Problem ◽  
The Cost ◽  
Specific Assignment ◽  
Selection Of

Mismanagement of routing and deliveries between sites of the same company or toward external sites leads to consequences in the cost of transport. When shipping alternatives exist, the selection of the appropriate shipping alternative (mode) for each shipment may result in significant cost savings. In this paper, the authors examine a class of vehicle routing in which a fixed internal fleet is available at the warehouse in the presence of an external transporter. The authors describe hybrid Iterated Density Estimation Evolutionary Algorithm with 2-opt local search to determine the specific assignment of each tour to a private vehicle (internal fleet) or an outside carrier (external fleet). Experimental results show that this method is effective, allowing the discovery of new best solutions for well-known benchmarks.

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