Gliding robotic fish, a new type of underwater robot, combines both strengths of underwater gliders and robotic fish, featuring long operation duration and high maneuverability. In this paper, we present both analytical and experimental results on a novel gliding motion, tail-enabled three-dimensional (3D) spiraling, which is well suited for sampling a water column. A dynamic model of a gliding...

This paper provides analytical insights into the hypothesis that fish exploit resonance to reduce the mechanical cost of swimming. A simple body-fluid fish model, representing carangiform locomotion, is developed. Steady swimming at various speeds is analysed using optimal gait theory by minimizing bending moment over tail movements and stiffness, and the results are shown to match with data fr...

In this paper, a carangiform robotic fish with 4-DoF (degree of freedom) tail has been developed. The robotic fish has capability of swimming under two modes that are radio control and autonomous swimming. Experiments were conducted to investigate the influences of characteristic parameters including the frequency, the amplitude, the wave length, the phase difference and the coefficient on forw...

In the most application of nozzle with gas-liquid two-phase flow, the quality of mixture in exhaust of nozzle is the most important parameter as well as the flow velocity. On the other hand, in some industrial application, such as water injection in forced induction (turbocharged or supercharged) internal combustion engine the spray quality is the main goal of designing. In this case and for im...

Local electric fields generated by the electric organ discharge of Gymnotus carapo were explored at selected points on the skin of an emitter fish ('local self-generated fields') and on the skin of a conspecific ('local conspecific-generated fields') using a specially designed probe. Local self-generated fields showed a constant pattern along the body of the fish. At the head, these fields were...

Compressible gas flow inside a convergent-divergent nozzle and its exhaust plume atdifferent nozzle pressure ratios (NPR) have been numerically studied with severalturbulence models. The numerical results reveal that, the SST k–ω model give the bestresults compared with other models in time and accuracy. The effect of changes in value ofdivergence half-angle (ε ) on the nozzle performance, thru...

in this article, an algorithm for designing of a supersonic wind tunnel injection nozzle ejector is presented and based on this algorithm, a new ejector is designed for a supersonic wind tunnel. the injection nozzle consists of a volute, a nozzle, and several vanes. designed injection nozzle is simulated numerically, and the results are compared with the present injection nozzle. the results sh...

A quasi one-dimensional analysis of a STOVL aircraft nozzle in hover is performed to estimate the gross thrust coefficient as a function of nozzle pressure and nozzle area ratios. The analysis is supported by subscale, cold flow test results. The nozzle performance was found to be less than desirable in hover due to the overexpansion arising from the geometrical constraints of the existing nozzle.

In this study, the concentration levels of the probable carcinogenic PAH fractions, benzo[a]pyrene (BaP) and benzo[k]fluoranthrene (BkF) in fillets of some processed fish species were investigated. Fish species comprising Merluccius poli (hake), Tyrsites atun (snoek), Seriola lalandi (yellow-tail) and Brama brama (angel fish) were bought in fish shops at Gordon's Bay, Western Cape, South Africa...