The turning- and linear-maneuvering performance of birds: the cost of efficiency for coursing insectivores

1998 ◽  
Vol 76 (6) ◽  
pp. 1063-1079 ◽  
Author(s):  
Douglas R Warrick
Keyword(s):  
Aspect Ratio ◽  
High Efficiency ◽  
Flight Morphology ◽  
Aerial Insectivores ◽  
The Cost ◽  
Performance Demands

To examine the performance compromises necessitated by adaptations for high efficiency in flight, such as highaspect ratio wings, the flight morphology and acceleration performance of a guild of coursing aerial insectivores (swifts andswallows) were compared with those of a guild of avian generalists. Though phylogenetic non-independence made inference ofadaptation difficult, biologically significant differences in aspect ratio and acceleration performance probably exist between thetwo groups of birds. A model of aerial insectivory is presented to illustrate the performance demands of this foraging methodand the impacts of the compromises between high efficiency in sustained flight and turning- and linear-maneuveringperformance.

Tail shapes lead to different propulsive mechanisms in the body/caudal fin undulation of fish

2020 ◽  
pp. 095440622096768
Author(s):  
Jialei Song ◽  
Yong Zhong ◽  
Ruxu Du ◽  
Ling Yin ◽  
Yang Ding
Keyword(s):  
Numerical Simulation ◽  
Aspect Ratio ◽  
High Efficiency ◽  
The Body ◽  
Caudal Fin ◽  
Fish Model ◽  
Swimming Efficiency ◽  
Simulation Results ◽  
Propulsive Mechanism ◽  
High Depth

In this paper, we investigate the hydrodynamics of swimmers with three caudal fins: a round one corresponding to snakehead fish ( Channidae), an indented one corresponding to saithe ( Pollachius virens), and a lunate one corresponding to tuna ( Thunnus thynnus). A direct numerical simulation (DNS) approach with a self-propelled fish model was adopted. The simulation results show that the caudal fin transitions from a pushing/suction combined propulsive mechanism to a suction-dominated propulsive mechanism with increasing aspect ratio ( AR). Interestingly, different from a previous finding that suction-based propulsion leads to high efficiency in animal swimming, this study shows that the utilization of suction-based propulsion by a high- AR caudal fin reduces swimming efficiency. Therefore, the suction-based propulsive mechanism does not necessarily lead to high efficiency, while other factors might play a role. Further analysis shows that the large lateral momentum transferred to the flow due to the high depth of the high- AR caudal fin leads to the lowest efficiency despite the most significant suction.

scholarly journals Optical spin-symmetry breaking for high-efficiency directional helicity-multiplexed metaholograms

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Muhammad Ashar Naveed ◽  
Muhammad Afnan Ansari ◽  
Inki Kim ◽  
Trevon Badloe ◽  
Joohoon Kim ◽  
...  
Keyword(s):  
High Efficiency ◽  
Spin Symmetry ◽  
Cost Effective ◽  
Dielectric Materials ◽  
Additional Degree ◽  
Cost Effective Alternative ◽  
Spin Orbit Interactions ◽  
Smart Mobile ◽  
The Cost ◽  
Hydrogenated Amorphous

AbstractHelicity-multiplexed metasurfaces based on symmetric spin–orbit interactions (SOIs) have practical limits because they cannot provide central-symmetric holographic imaging. Asymmetric SOIs can effectively address such limitations, with several exciting applications in various fields ranging from asymmetric data inscription in communications to dual side displays in smart mobile devices. Low-loss dielectric materials provide an excellent platform for realizing such exotic phenomena efficiently. In this paper, we demonstrate an asymmetric SOI-dependent transmission-type metasurface in the visible domain using hydrogenated amorphous silicon (a-Si:H) nanoresonators. The proposed design approach is equipped with an additional degree of freedom in designing bi-directional helicity-multiplexed metasurfaces by breaking the conventional limit imposed by the symmetric SOI in half employment of metasurfaces for one circular handedness. Two on-axis, distinct wavefronts are produced with high transmission efficiencies, demonstrating the concept of asymmetric wavefront generation in two antiparallel directions. Additionally, the CMOS compatibility of a-Si:H makes it a cost-effective alternative to gallium nitride (GaN) and titanium dioxide (TiO2) for visible light. The cost-effective fabrication and simplicity of the proposed design technique provide an excellent candidate for high-efficiency, multifunctional, and chip-integrated demonstration of various phenomena.

A Determinant Elimination Method for Bottleneck Assignment and Generalized Assignment Problems

2012 ◽  
Vol 239-240 ◽  
pp. 1522-1527
Author(s):  
Wen Bo Wu ◽  
Yu Fu Jia ◽  
Hong Xing Sun
Keyword(s):  
Computational Complexity ◽  
Optimization Algorithm ◽  
Assignment Problem ◽  
Numerical Experiments ◽  
High Efficiency ◽  
Synthesis Method ◽  
Assignment Problems ◽  
Generalized Assignment ◽  
The Cost ◽  
Time And Space Complexity

The bottleneck assignment (BA) and the generalized assignment (GA) problems and their exact solutions are explored in this paper. Firstly, a determinant elimination (DE) method is proposed based on the discussion of the time and space complexity of the enumeration method for both BA and GA problems. The optimization algorithm to the pre-assignment problem is then discussed and the adjusting and transformation to the cost matrix is adopted to reduce the computational complexity of the DE method. Finally, a synthesis method for both BA and GA problems is presented. The numerical experiments are carried out and the results indicate that the proposed method is feasible and of high efficiency.

Contour Extraction of Cerebrovascular Based on Maximum Optimization Cost

2011 ◽  
Vol 204-210 ◽  
pp. 1415-1418
Author(s):  
De Jiang Zhang ◽  
Na Na Dong ◽  
Xiao Mei Lin
Keyword(s):  
Dynamic Programming ◽  
Blood Vessel ◽  
High Efficiency ◽  
High Accuracy ◽  
Differential Method ◽  
Cost Curve ◽  
Contour Extraction ◽  
Target Image ◽  
The Cost ◽  
Conventional Algorithm

By studying the conventional algorithm of contour extraction, a new method of contour extraction in blood vessel of brain is proposed based on the MOC maximum optimization cost. First of all, the theory computes the gray differential of the image by conventional differential method to build the cost space. Then, by using dynamic programming theory, the maximum optimization cost curve in the space is extracted to serve as the specific cerebrovascular profile. The experiments show that this method ensures high efficiency in extracting cerebrovascular contour and a high accuracy in positioning cerebrovascular contour, and it diminishes the target image ambiguity caused by noise to improve the anti-interference ability of Contour extraction.

High-Efficiency Cut Blasting with Shell Radial Shaped Charge in Laboratory-Scale Blasting

2015 ◽  
Vol 1094 ◽  
pp. 445-450 ◽  
Author(s):  
Wei Chen ◽  
Hong Hao Ma ◽  
Zhao Wu Shen ◽  
De Bao Wang
Keyword(s):  
High Efficiency ◽  
Circular Tube ◽  
Rock Breaking ◽  
Shaped Charge ◽  
Axial Line ◽  
Rock Excavation ◽  
Crack Network ◽  
Utilization Ratio ◽  
The Cost ◽  
The Ideal

Due to the inefficiency problem of the cut blasting in rock excavation and rock breaking, a shell radial shaped charge device was proposed based of the ideal of ‘cutting to slotting’ and it was validated through experiments. For this device, the shell materials are used to be shaped materials and multiple shaped ring is designed on the circular tube. It can not only reduce charge quantity but also raise the utilization ratio of explosive energy. After explosion, multiple radial shaped charge jets can be formed along the axial line in sequence and then the surrounding rock mass would be cracked. The crack network will be formed along with the further extension of the fraction under the action of quasi static loading of detonation gas. The shell radial shaped charge device was tested through the cut blasting model experiment. Experimental results show that the utilization ratio of blasting hole nearly approaches 98% with this device. The blasting efficiency and cyclical footage can be improved effectively and the cost of drifting can also be reduced.

Experimental Performance of a Trochoidal Propeller with High-Aspect-Ratio Blades

1989 ◽  
Vol 26 (03) ◽  
pp. 192-201 ◽  
Author(s):  
Neil Bose ◽  
Peter S. K. Lai
Keyword(s):  
Aspect Ratio ◽  
High Efficiency ◽  
Open Water ◽  
Finite Amplitude ◽  
Dynamic Stall ◽  
Frictional Drag ◽  
Overall Performance ◽  
Small Ship ◽  
Propeller Performance ◽  
Thrust And Torque

Open-water experiments were done on a model of a cycloidal-type propeller with a trochoidal blade motion. This propeller had three blades with an aspect ratio of 10. These experiments included the measurement of thrust and torque of the propeller over a range of advance ratios. Tests were done for forward and reverse operation, and at zero speed (the bollard pull condition). Results from these tests are presented and compared with: a multiple stream-tube theoretical prediction of the performance of the propeller; and a prediction of the performance of a single blade of the propeller, oscillating in heave and pitch, using unsteady small-amplitude hydrofoil theory with corrections for finite amplitude motion, finite span, and frictional drag. At present, neither of these theories gives a completely accurate prediction of propeller performance over the whole range of advance ratios, but a combination of these approaches, with an allowance for dynamic stall of the blades, should lead to a reliable simple theory for overall performance prediction. Application of a propeller of this type to a small ship is discussed. The aim of the design is to produce a lightly loaded propeller with a high efficiency of propulsion.

scholarly journals A structure-exploiting numbering algorithm for finite elements on extruded meshes, and its performance evaluation in Firedrake

2016 ◽  
Vol 9 (10) ◽  
pp. 3803-3815 ◽  
Author(s):  
Gheorghe-Teodor Bercea ◽  
Andrew T. T. McRae ◽  
David A. Ham ◽  
Lawrence Mitchell ◽  
Florian Rathgeber ◽  
...  
Keyword(s):  
Finite Element ◽  
Performance Evaluation ◽  
Finite Elements ◽  
Aspect Ratio ◽  
Three Dimensional ◽  
Data Layout ◽  
Element System ◽  
Continuous Galerkin ◽  
Performance Penalty ◽  
The Cost

Abstract. We present a generic algorithm for numbering and then efficiently iterating over the data values attached to an extruded mesh. An extruded mesh is formed by replicating an existing mesh, assumed to be unstructured, to form layers of prismatic cells. Applications of extruded meshes include, but are not limited to, the representation of three-dimensional high aspect ratio domains employed by geophysical finite element simulations. These meshes are structured in the extruded direction. The algorithm presented here exploits this structure to avoid the performance penalty traditionally associated with unstructured meshes. We evaluate the implementation of this algorithm in the Firedrake finite element system on a range of low compute intensity operations which constitute worst cases for data layout performance exploration. The experiments show that having structure along the extruded direction enables the cost of the indirect data accesses to be amortized after 10–20 layers as long as the underlying mesh is well ordered. We characterize the resulting spatial and temporal reuse in a representative set of both continuous-Galerkin and discontinuous-Galerkin discretizations. On meshes with realistic numbers of layers the performance achieved is between 70 and 90 % of a theoretical hardware-specific limit.

scholarly journals Experimental Measurement of Rice Husk Effectiveness as an Alternative Adsorbent for Turbidity Reduction in Synthetic Water

2019 ◽  
Vol 22 (4) ◽  
pp. 329-334
Author(s):  
Noora Saad Faraj Al-Dulaimi ◽  
Samara Saad Faraj Al-Dulaimi
Keyword(s):  
Rice Husk ◽  
Rural Areas ◽  
Urban Areas ◽  
High Efficiency ◽  
Low Cost ◽  
Water Turbidity ◽  
Cheap Alternative ◽  
Quality Water ◽  
Ph Level ◽  
The Cost

Providing a clean and high quality drinking water to both rural as well as urban areas is a great challenge by itself, adding to it the large volume requirements of such water at high population areas means a very high cost for such industry because mainly of the cost of expensive commercially available adsorbent used in this process. This led inhabitants of the remote and/or rural areas to use less quality water with all its risks and health challenges. In this study, a locally collected rice husk is tested to be used as an alternative adsorbent to the expensive common commercial ones. Parameters like adsorbent dosage, initial concentration of turbidity, and pH level were tested to investigate their effects on the process. Treatment of synthetic turbid water was done after changing these parameters to measure the effect of each parameter alone and the results showed a set of parameters that can be used to achieve high efficiency of turbidity removal. The study concluded that rice husk can be used as a well cheap alternative adsorbent to reduce the river water turbidity due to its availability and low cost with a decent removal efficiency approaching 95%.

Peroxovanadates and Its Bio-Mimicking Relation with Vanadium Haloperoxidases

2016 ◽  
pp. 197-219
Author(s):  
Pranjal Saikia ◽  
Saitanya Kumar Bharadwaj ◽  
Abu Taleb Miah
Keyword(s):  
Amino Acids ◽  
Active Site ◽  
High Efficiency ◽  
Recombinant Enzymes ◽  
Vanadium Compounds ◽  
Reaction Conditions ◽  
The Cost ◽  
Major Emphasis ◽  
Protein Active Site

Vanadium Haloperoxidases (VHPOs) have been used in a variety of biotransformations showing remarkable stereoselectivity and regiospecificity. The high efficiency of the enzyme is influenced by the protein active site and the role of certain amino acids in activation of vanadium(V)-bound peroxide for halide oxidation. The use of natural or recombinant enzymes, or biomimetic vanadium compounds brings up issues regarding the cost of production and reaction conditions. In this chapter, the primary intent is to provide a simple and clear picture of functional mimicking nature of peroxovanadium compounds with haloperoxidases enzymes to the readers. Major emphasis would be given to examine the reactivity of the vanadium haloperoxidases with mechanism.

scholarly journals FTP: An Approximate Fast Privacy-Preserving Equality Test Protocol for Authentication in Internet of Things

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Youwen Zhu ◽  
Yue Zhang ◽  
Jiabin Yuan ◽  
Xianmin Wang
Keyword(s):  
Internet Of Things ◽  
High Efficiency ◽  
Privacy Preserving ◽  
Fundamental Operation ◽  
Test Protocol ◽  
Simulation Experiments ◽  
Iot Applications ◽  
Running Cost ◽  
The Cost ◽  
Equality Test

Privacy-preserving string equality test is a fundamental operation of many algorithms, including privacy-preserving authentication in Internet of Things (IoT). Existing secure equality test schemes can theoretically achieve string equality comparison and preserve the private strings. However, they suffer from heavy computation and communication cost, especially while the strings are of hundreds of bits or longer, which is not suitable for IoT applications. In this paper, we propose an approximate  Fast privacy-preserving equality  Test  Protocol (FTP), which can securely complete string equality test and achieve high running efficiency at the cost of little accuracy loss. We strictly analyze the accuracy of our proposed scheme and formally prove its security. Additionally, we leverage extensive simulation experiments to evaluate the running cost, which confirms our high efficiency; for instance, our proposed FTP can securely compare two 256-bit strings within 0.7 seconds on ordinary laptops.

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