scholarly journals A Numerical Model for the Analysis of the Locomotion of a Cownose Ray

2021 ◽  
Author(s):  
Giovanni Bianchi ◽  
Simone Cinquemani ◽  
Paolo Schito ◽  
Ferruccio Resta
Keyword(s):  
Energy Efficiency ◽  
Autonomous Underwater Vehicles ◽  
Fluid Velocity ◽  
High Energy ◽  
Momentum Conservation ◽  
Pectoral Fins ◽  
Cownose Ray ◽  
Swimming Motion ◽  
Batoid Fishes ◽  
Promising Source

Abstract Among all aquatic species, mantas and rays swim by flapping their pectoral fins; this motion is similar to other fishes in terms of efficiency, but it gives better maneuverability and agility in turning. The fin motion is featured by a traveling wave going opposite to the forward motion, producing a force thanks to momentum conservation. This article aims at understanding the swimming dynamics of rays, focusing on energy efficiency. A CFD model of the swimming motion of a cownose ray has been implemented in OpenFOAM, simulating the acceleration of the fish from still to the steady-state velocity using an overset mesh. In this analysis, the 1-DOF dynamics of forward swimming is solved together with the fluid velocity and pressure. The effect of frequency and wavelength of fin motion on thrust, power, and velocity has been investigated and an analysis of the vortices in the wake showed has been performed. The energy efficiency of a self-propelled body has been defined in a novel way and it has been calculated for different motion conditions. The results showed that batoid fishes swim with high energy efficiency and that they are a promising source of inspiration for biomimetic autonomous underwater vehicles.

scholarly journals Bio-Inspired Design of An Underwater Robot Exploiting Fin Undulation Propulsion

2021 ◽  
Vol 11 (6) ◽  
pp. 2556
Author(s):  
Giovanni Bianchi ◽  
Simone Cinquemani ◽  
Ferruccio Resta
Keyword(s):  
Control Algorithm ◽  
Autonomous Underwater Vehicles ◽  
Fish Swimming ◽  
Underwater Robots ◽  
Cownose Ray ◽  
Thrust Generation ◽  
Robot Behavior ◽  
Batoid Fishes ◽  
Underwater Exploration ◽  
Promising Source

Interest in autonomous underwater vehicles is constantly increasing following the emerging needs of underwater exploration and military purposes. Thus, several new propulsion mechanisms are studied and developed. Fish swimming is a promising source of inspiration because they outperform conventional propellers in terms of energy efficiency and maneuvrability. Their advantages are not only due to the streamlined shape and their low-drag skin but also, above all, due to the particular fin motion, which makes thrust generation possible with small energy dissipation. This paper analyses the motion of batoid fishes that are considered highly efficient by biologists. Their motion is reproduced by different linkage mechanisms optimized to fit underwater robots. A bioinspired robot mimicking cownose ray locomotion is, then, designed and built. Numerical analysis of its dynamics allows us to measure the size of actuators and to estimate the robot behavior. Finally, the control algorithm that maintains the mechanism synchronization according to different strategies is described and some experimental results are presented.

Reactions in Activated Peroxide Systems and their Influences on Bleaching Performance

2020 ◽  
Vol 17 ◽  
Author(s):  
Xiaoyan Wang ◽  
Jinmei Du ◽  
Changhai Xu
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Energy Efficiency ◽  
Textile Industry ◽  
High Energy ◽  
Side Reactions ◽  
Competitive Reactions ◽  
High Energy Efficiency ◽  
Hydrolysis Of ◽  
Bleach Activators

Abstract:: Activated peroxide systems are formed by adding so-called bleach activators to aqueous solution of hydrogen peroxide, developed in the seventies of the last century for use in domestic laundry for their high energy efficiency and introduced at the beginning of the 21st century to the textile industry as an approach toward overcoming the extensive energy consumption in bleaching. In activated peroxide systems, bleach activators undergo perhydrolysis to generate more kinetically active peracids that enable bleaching under milder conditions while hydrolysis of bleach activators and decomposition of peracids may occur as side reactions to weaken the bleaching efficiency. This mini-review aims to summarize these competitive reactions in activated peroxide systems and their influence on bleaching performance.

scholarly journals Degradation Investigation of Electrocatalyst in Proton Exchange Membrane Fuel Cell at a High Energy Efficiency

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3932
Author(s):  
Jie Song ◽  
Qing Ye ◽  
Kun Wang ◽  
Zhiyuan Guo ◽  
Meiling Dou
Keyword(s):  
Energy Efficiency ◽  
Single Cell ◽  
Proton Exchange Membrane ◽  
Cell Voltage ◽  
High Energy ◽  
Proton Exchange ◽  
Pt Catalyst ◽  
Operation Conditions ◽  
High Efficient ◽  
Exchange Membrane

The development of high efficient stacks is critical for the wide spread application of proton exchange membrane fuel cells (PEMFCs) in transportation and stationary power plant. Currently, the favorable operation conditions of PEMFCs are with single cell voltage between 0.65 and 0.7 V, corresponding to energy efficiency lower than 57%. For the long term, PEMFCs need to be operated at higher voltage to increase the energy efficiency and thus promote the fuel economy for transportation and stationary applications. Herein, PEMFC single cell was investigated to demonstrate its capability to working with voltage and energy efficiency higher than 0.8 V and 65%, respectively. It was demonstrated that the PEMFC encountered a significant performance degradation after the 64 h operation. The cell voltage declined by more than 13% at the current density of 1000 mA cm−2, due to the electrode de-activation. The high operation potential of the cathode leads to the corrosion of carbon support and then causes the detachment of Pt nanoparticles, resulting in significant Pt agglomeration. The catalytic surface area of cathode Pt is thus reduced for oxygen reduction and the cell performance decreased. Therefore, electrochemically stable Pt catalyst is highly desirable for efficient PEMFCs operated under cell voltage higher than 0.8 V.

scholarly journals Overall Efficiency of On-Site Production and Storage of Solar Thermal Energy

2021 ◽  
Vol 13 (3) ◽  
pp. 1360
Author(s):  
Teodora M. Șoimoșan ◽  
Ligia M. Moga ◽  
Livia Anastasiu ◽  
Daniela L. Manea ◽  
Aurica Căzilă ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Thermal Energy ◽  
Urban Areas ◽  
Renewable Energy Sources ◽  
Multicriteria Analysis ◽  
High Energy ◽  
Solar Thermal ◽  
Solar Thermal Energy ◽  
The Impact ◽  
And Storage

Harnessing renewable energy sources (RES) using hybrid systems for buildings is almost a deontological obligation for engineers and researchers in the energy field, and increasing the percentage of renewables within the energy mix represents an important target. In crowded urban areas, on-site energy production and storage from renewables can be a real challenge from a technical point of view. The main objectives of this paper are quantification of the impact of the consumer’s profile on overall energy efficiency for on-site storage and final use of solar thermal energy, as well as developing a multicriteria assessment in order to provide a methodology for selection in prioritizing investments. Buildings with various consumption profiles lead to achieving different values of performance indicators in similar configurations of storage and energy supply. In this regard, an analysis of the consumption profile’s impact on overall energy efficiency, achieved in the case of on-site generation and storage of solar thermal energy, was performed. The obtained results validate the following conclusion: On-site integration of solar systems allowed the consumers to use RES at the desired coverage rates, while restricted by on-site available mounting areas for solar fields and thermal storage, under conditions of high energy efficiencies. In order to segregate the results and support optimal selection, a multicriteria analysis was carried out, having as the main criteria the energy efficiency indicators achieved by hybrid heating systems.

High Energy Efficiency and Stability for Photoassisted Aqueous Lithium–Iodine Redox Batteries

2016 ◽  
Vol 1 (4) ◽  
pp. 806-813 ◽  
Author(s):  
Georgios Nikiforidis ◽  
Keisuke Tajima ◽  
Hye Ryung Byon
Keyword(s):  
Energy Efficiency ◽  
High Energy ◽  
High Energy Efficiency

In-situ quantification of NO synthesis in a warm air glow discharge by WMS-based Mid-IR QCL absorption spectroscopy

2022 ◽  
Author(s):  
Chuanqi Wang ◽  
Junjie Qiao ◽  
Yijia Song ◽  
Qi Yang ◽  
Dazhi Wang ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Glow Discharge ◽  
Absorption Spectroscopy ◽  
Energy Cost ◽  
High Energy ◽  
Cathode Region ◽  
Synthesis Rate ◽  
No Production ◽  
Airflow Rate

Abstract Nitric oxide (NO) is one of the most crucial products in the plasma-based nitrogen fixation process. In this work, in-situ measurements were performed for quantifying the NO synthesis spatially in a warm air glow discharge, through the method of Mid-infrared quantum cascade laser absorption spectroscopy (QCL-AS). Two ro-vibrational transitions at 1900.076 cm-1 and 1900.517 cm-1 of the ground-state NO(X) were probed sensitively by the help of the wavelength modulation spectroscopy (WMS) approach to increase the signal/noise (S/N) level. The results show a decline trend of NO synthesis rate along the discharge channel from the cathode to the anode. However, from the point of energy efficiency, the cathode region is of significantly low energy efficiency of NO production. Severe disproportionality was found for the high energy consumption but low NO production in the region of cathode area, compared to that in the positive column zone. Further analysis demonstrates the high energy cost of NO production in the cathode region, is ascribed to the extremely high reduced electric field E/N therein not selectively preferable for the processes of vibrational excitation or dissociation of N2 and O2 molecules. This drags down the overall energy efficiency of NO synthesis by this typical warm air glow discharge, particularly for the ones with short electrode gaps. Limitations of further improving the energy cost of NO synthesis by variations of the discharge operation conditions, such as discharge current or airflow rate, imply other effective manners able to tune the energy delivery selectively to the NO formation process, are sorely needed.

Electrochemical lithium recovery with lithium iron phosphate: What causes performance degradation and how can we improve the stability?

2021 ◽  
Author(s):  
Lei Wang ◽  
Kathleen C Frisella ◽  
Pattarachai Srimuk ◽  
Oliver Janka ◽  
Guido Kickelbick ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Manganese Oxide ◽  
Lithium Iron Phosphate ◽  
Iron Phosphate ◽  
High Energy ◽  
Performance Degradation ◽  
Electrochemical Processes ◽  
High Energy Efficiency ◽  
The Stability

Electrochemical processes enable fast lithium extraction, for example, from brines, with high energy efficiency and stability. Lithium iron phosphate (LiFePO4) and manganese oxide (λ-MnO2) have usually been employed as the...

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