scholarly journals Measuring power input, power output and energy conversion efficiency in un-instrumented flying birds

2020 ◽  
Vol 223 (18) ◽  
pp. jeb223545
Author(s):  
Linus Hedh ◽  
Christopher G. Guglielmo ◽  
L. Christoffer Johansson ◽  
Jessica E. Deakin ◽  
Christian C. Voigt ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Empirical Studies ◽  
Power Input ◽  
Energy Conversion Efficiency ◽  
Input Power ◽  
Specific Power ◽  
Composition Analysis ◽  
Flight Behaviour ◽  
Bird Flight ◽  
Weight Lift

ABSTRACTCost of flight at various speeds is a crucial determinant of flight behaviour in birds. Aerodynamic models, predicting that mechanical power (Pmech) varies with flight speed in a U-shaped manner, have been used together with an energy conversion factor (efficiency) to estimate metabolic power (Pmet). Despite few empirical studies, efficiency has been assumed constant across flight speeds at 23%. Ideally, efficiency should be estimated from measurements of both Pmech and Pmet in un-instrumented flight. Until recently, progress has been hampered by methodological constraints. The main aim of this study was to evaluate recently developed techniques and estimate flight efficiency across flight speeds. We used the 13C-labelled sodium bicarbonate method (NaBi) and particle image velocimetry (PIV) to measure Pmet and Pmech in blackcaps flying in a wind tunnel. We also cross-validated measurements made by NaBi with quantitative magnetic resonance (QMR) body composition analysis in yellow-rumped warblers. We found that Pmet estimated by NaBi was ∼12% lower than corresponding values estimated by QMR. Pmet varied in a U-shaped manner across flight speeds in blackcaps, but the pattern was not statistically significant. Pmech could only be reliably measured for two intermediate speeds and estimated efficiency ranged between 14% and 22% (combining the two speeds for raw and weight/lift-specific power, with and without correction for the ∼12% difference between NaBi and QMR), which were close to the currently used default value. We conclude that NaBi and PIV are viable techniques, allowing researchers to address some of the outstanding questions regarding bird flight energetics.

scholarly journals Exploring harnessing wind power in moving reference frames with application to vehicles

2019 ◽  
Vol 11 (9) ◽  
pp. 168781401986568
Author(s):  
Oleg Goushcha ◽  
Robert Felicissimo ◽  
Amir H Danesh-Yazdi ◽  
Yiannis Andreopoulos
Keyword(s):  
Energy Conversion ◽  
Wind Power ◽  
Conversion Efficiency ◽  
Reference Frames ◽  
Energy Conversion Efficiency ◽  
High Energy ◽  
High Mass ◽  
Specific Power ◽  
Moving Frames ◽  
Atmospheric Conditions

The possibility of extracting wind power from unique configurations embedded in moving vehicles using microturbine devices has been investigated. In such environments with moving frames or platforms, powered either by humans like bicycles or by chemical reactions like automobiles, the specific power of the air motion is much greater and less intermittent than in stationary wind turbines anchored to the ground in open atmospheric conditions. In a translational frame of reference, the rate of work done by the drag force acting on the wind harnessing device due to the relative motion of air should be taken into account in the overall performance evaluation through an energy balance. A device with a venting tube has been tested that connects a high-pressure stagnating flow region in the front of the vehicle with a low-pressure region at its rear. Our analysis identified two key areas to focus on for potentially significant rewards: (1) vehicles with high energy conversion efficiency, which require a high mass flow rate through the venting duct, and (2) vehicles with low energy conversion efficiency with wakes, which will be globally affected by the introduction of the venting duct device in a manner that reduces their drag so that there is a net gain in power generation.

Effect of external sound superimposed on the self-excited oscillation in loop-tube thermoacoustic system

2021 ◽  
Author(s):  
Koto Hiramatsu ◽  
Shin-ichi SAKAMOTO ◽  
Yoshiaki Watanabe
Keyword(s):  
Energy Conversion ◽  
Conversion Efficiency ◽  
Particle Velocity ◽  
Sound Field ◽  
Energy Conversion Efficiency ◽  
Input Power ◽  
The Self ◽  
Straight Tube ◽  
Excited Oscillation ◽  
Tube Type

Abstract The influence of application of external sound to loop-tube type thermoacoustic system on the energy conversion efficiency is experimentally examined. The investigation is carried out by paying attention on the effect of loudspeaker (SP) set as external sound source. As a result, it is found that the setting of SP affects the sound field in the system and the amount of energy generation increases or decreases. The increasing or decreasing effect differs depending on the setting position of SP. Furthermore, it is confirmed that, provided SP is set near the node of particle velocity, the sound energy can be increased by more than the input power to SP, without changing the sound field in the tube. From these results it can be confirmed that, similar to straight-tube type thermoacoustic system, the energy conversion efficiency can be enhanced by setting SP at suitable position even in loop-tube type without end surfaces.

Branched ZnO Nanowires for Enhancing Energy Conversion Efficiency of Dye-Sensitized Solar Cells

2008 ◽  
Author(s):  
Hsin-Ming Cheng ◽  
Wei-Hao Chiu ◽  
Chia-Hua Lee ◽  
Song-Yeu Tsai ◽  
Wen-Feng Hsieh
Keyword(s):  
Solar Cells ◽  
Energy Conversion ◽  
Conversion Efficiency ◽  
Dye Sensitized Solar Cells ◽  
Energy Conversion Efficiency ◽  
Zno Nanowires ◽  
Dye Sensitized ◽  
Sensitized Solar Cells

Current progress and performance improvement of Pt/C catalysts for fuel cells

2020 ◽  
Vol 8 (46) ◽  
pp. 24284-24306
Author(s):  
Xuefeng Ren ◽  
Yiran Wang ◽  
Anmin Liu ◽  
Zhihong Zhang ◽  
Qianyuan Lv ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Energy Conversion ◽  
Performance Improvement ◽  
Electric Energy ◽  
Energy Conversion Efficiency ◽  
High Energy ◽  
Carnot Cycle ◽  
High Energy Conversion Efficiency ◽  
And Performance

Fuel cell is an electrochemical device, which can directly convert the chemical energy of fuel into electric energy, without heat process, not limited by Carnot cycle, high energy conversion efficiency, no noise and pollution.

First-principles study on the electronic and optical properties of the orthorhombic CsPbBr3 and CsPbI3 with Cmcm space group

2021 ◽  
Author(s):  
Xianhao Zhao ◽  
Tianyu Tang ◽  
Quan Xie ◽  
like gao ◽  
Limin Lu ◽  
...  
Keyword(s):  
Optical Properties ◽  
Solar Cells ◽  
Energy Conversion ◽  
Conversion Efficiency ◽  
First Principles ◽  
Energy Conversion Efficiency ◽  
Space Group ◽  
Absorbing Materials ◽  
Halide Perovskites ◽  
Lead Halide

The cesium lead halide perovskites are regarded as effective candidates for light-absorbing materials in solar cells, which have shown excellent performances in experiments such as promising energy conversion efficiency. In...

scholarly journals Optical Parametric Oscillation with Ultra-low Power Threshold in a Dimer of Active-Passive Cavities

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 566
Author(s):  
Bo Lu ◽  
Chen-Rui Fan ◽  
Jun-Yang Song ◽  
Chuan Wang
Keyword(s):  
Pump Power ◽  
Energy Conversion ◽  
Energy Conversion Efficiency ◽  
Parametric Oscillation ◽  
Optical Parametric Oscillation ◽  
Optical Parametric ◽  
Non Linear ◽  
Oscillation Process ◽  
Power Threshold ◽  
Low Threshold

Optical parametric oscillation can convert the input laser into a couple of coherent optical output with signal and idler frequencies. It is an important method for the realization of the broadband middle infrared tunable lasers. The optical parametric oscillation process depends on the ultra-fast non-linear response of matter to light with a certain pump power. Therefore, reducing the pump threshold of the optical parametric oscillation process and improving the energy conversion efficiency are of great significance to the study of non-linear optics. In this paper, we construct a dimer system that couples a passive non-linear resonator to an active resonator. Based on the dimer system, an ultra-low threshold optical parametric oscillation generation method is proposed. By coupling the gain pump mode, the non-linear effect is effectively enhanced, the pump power threshold is reduced to half of when there is no gain, and the energy conversion efficiency is increased. We believe this research provides a feasible method for a low-threshold tunable and easy-to-integrate optical parametric oscillation laser source.

Sodium Vanadate/PEDOT Nanocables Rich with Oxygen Vacancies for High Energy Conversion Efficiency Zinc Ion Batteries

2021 ◽  
Author(s):  
Wenchao Bi ◽  
Guohua Gao ◽  
Guangming Wu ◽  
Muhammad Atif ◽  
Mohamad Alsalhi ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Conversion Efficiency ◽  
Oxygen Vacancies ◽  
Energy Conversion Efficiency ◽  
High Energy ◽  
Zinc Ion ◽  
Sodium Vanadate ◽  
High Energy Conversion Efficiency
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