Fin Side Research Articles

Anatomy and muscle activity of the dorsal fins in bamboo sharks and spiny dogfish during turning maneuvers

Stability and procured instability characterize two opposing types of swimming, steady and maneuvering, respectively. Fins can be used to manipulate flow to adjust stability during swimming maneuvers either actively using muscle control or passively by structural control. The function of the dorsal fins during turning maneuvering in two shark species with different swimming modes is investigated here using musculoskeletal anatomy and muscle function. White-spotted bamboo sharks are a benthic species that inhabits complex reef habitats and thus have high requirements for maneuverability. Spiny dogfish occupy a variety of coastal and continental shelf habitats and spend relatively more time cruising in open water. These species differ in dorsal fin morphology and fin position along the body. Bamboo sharks have a larger second dorsal fin area and proportionally more muscle insertion into both dorsal fins. The basal and radial pterygiophores are plate-like structures in spiny dogfish and are nearly indistinguishable from one another. In contrast, bamboo sharks lack basal pterygiophores, while the radial pterygiophores form two rows of elongated rectangular elements that articulate with one another. The dorsal fin muscles are composed of a large muscle mass that extends over the ceratotrichia overlying the radials in spiny dogfish. However, in bamboo sharks, the muscle mass is divided into multiple distinct muscles that insert onto the ceratotrichia. During turning maneuvers, the dorsal fin muscles are active in both species with no differences in onset between fin sides. Spiny dogfish have longer burst durations on the outer fin side, which is consistent with opposing resistance to the medium. In bamboo sharks, bilateral activation of the dorsal in muscles could also be stiffening the fin throughout the turn. Thus, dogfish sharks passively stiffen the dorsal fin structurally and functionally, while bamboo sharks have more flexible dorsal fins, which result from a steady swimming trade off.

The Optimization of Operation Characteristics for Finned Heat Pipe Radiator in Concentrating Photovoltaic System

Aiming at the problem of the concentrating solar cell efficiency restricted by the temperature. The closed two-phase thermosyphon could be used for heat dissipation in concentrat- ing solar cell with high heat flux, then water was selected as the working fluid. Numerical computation methods were adopted to study heat transfer performance of the finned heat pipe radiator in free convection. The temperature field, velocity field, total heat dissipating capacity of different fin pitch and side length as well as free convection heat transfer coefficient under the condition of constant temperature of parent tube were obtained. As a result, the fin side length had greater impact on the natural convection heat transfer coefficient and average total heat flux per unit area; the fin pitch had greater impact on the finned heat pipe radiator total heat dissipating capacity per unit length; the finned heat pipe radiator was the best when fin pitch was 3mm and fin side length was 90mm.

The Characteristic Temperature in the Definition of Heat Transfer Coefficient on the Fin Side Surface in Tube Bank Fin Heat Exchanger

The characteristic temperature in the definition of the fin side surface heat transfer coefficient of two tube bank fin heat exchangers is investigated in detail. The results reveal that if the average temperature of the fin side fluid is used in the definition of the fin side surface coefficient, a small discrepancy between the numerical and experimental results is obtained. The results not only give a technical definition of the characteristic temperature of the fin side surface heat transfer coefficient, but also imply that the discrepancy between experimental and numerical results may come from incorrect use of the characteristic temperature.

SONOS 플래시 메모리 소자의 구조와 크기에 따른 특성연구

In this paper, Fin-type silicon-oxide-nitride-oxide-silicon (SONOS) flash memory are fabricated and the electrical characteristics are analyzed. Compared to the planar-type SONOS devices, Fin-type SONOS devices show good short channel effect (SCE) immunity due to the enhanced gate controllability. In memory characteristics such as program/erase speed, endurance and data retention, Fin-type SONOS flash memory are also superior to those of conventional planar-type. In addition, Fin-type SONOS device shows improved SCE immunity in accordance with the decrease of Fin width. This is known to be due to the fully depleted mode operation as the Fin width decreases. In Fin-type, however, the memory characteristic improvement is not shown in narrower Fin width. This is thought to be caused by the Fin structure where the electric field of Fin top can interference with the Fin side electric field and be lowered.

An Improved Particle Swarm Algorithm for Optimal Design of Plate-Fin Heat Exchangers

In this paper, an improved particle swarm optimization (PSO) was used to optimize the structure dimensions of the plate-fin heat exchangers (PFHEs). The major objectives are to minimize the total weight and total annual cost of the PFHEs for given constrained conditions. The total weight target ensures an exchanger of the smallest size with minimum capital cost, whereas the annual cost target yields the optimum pressure drops accounting for the trade-off between power consumption and heat exchanger weight. The total length and width of the PFHE core, number of hot side layers, fin height, and pitch on each side of the PFHE are considered as optimization variables. The logarithmic mean temperature difference method is used for the design of the PFHE. Also compared with the results obtained by PSO and the traditional genetic algorithm, the PSO algorithm presents a shorter computational time and better results under the same design parameters and the same optimization variables.

Heat and mass transfer studies on plate fin-and-elliptical tube type metal hydride reactors

In the present work a two-dimensional transient model to study the heat and mass transfer characteristics of plate fin-and-elliptical tube type metal hydride reactors is presented. The relevant governing equations are solved numerically. The heat transfer coefficient and pressure drop on external fin side are estimated using available correlations. Effects of external fluid flow rate and temperature on the fin-and-tube metal hydride reactor are studied. Results show that the use of elliptical metal hydride tubes in place of the standard circular tubes give rise to compact systems in addition to considerably lower fan power consumption, with very little change in the average heat and hydrogen transfer rates. Even though the performance of the reactor depends very much on the fin-and-tube arrangement, for all the arrangements considered here, the reactors with elliptical tubes were found to perform better in terms of compactness, weight and fan power consumption. Considering the aspects of mean hydride bed thickness, tube wall thickness, tube mass, compactness, heat and hydrogen transfer rates and fan power consumption, elliptical tubes of 0.6 eccentricity appear to offer the best solution for the given application.

잠수 휜 킥 유형별 신체중심 추진 동작의 운동학적 분석

The study was undertaken to present the quantitative materials available in underwater industries, underwater rehabilitation & physical training through comparison & analysis of effects contributing to propulsion of COG by types of fin-kick in underwater activities. For this 3D cinematography was performed for the skilled subjective and conclusions obtained on the basis of analysis of kinematic variables were as follows. In temporal variable the delay in the order of flutter>side>dolphin kick in elapsed time by total & phase resulted in longer sliding phase by larger fin kick of extension & flexion of both leg and thus more contributed in propulsion of COG. than those of the otherwise. In linear variable the contribution ratio to the result of propulsion of COG in both propulsive(mean <TEX>$35.39{\pm}7.93cm$</TEX> in Y axis) and sliding phases(mean <TEX>$66.36{\pm}11.01cm$</TEX> in Y axis)was shown to be order of flutter>dolphin>side fin kick. the maximum velocity of COG in Y direction was showed in both propulsive and sliding phases, and the contribution ratio to the propulsion of COG was in the order of flutter<TEX>$\geq$</TEX>dolphin>side fin kick. In angular variable the Significant difference in angle of leg joint by types of fin kick in both leg was showed but no routine order. The Significant difference in angular velocity of leg joint by types of fin kick in both leg was showed in the order of flutter>dolphin<TEX>$\geq$</TEX>side fin kick in propulsive but no in sliding phase. The Fluid resistance by tilting angle of trunk in both propulsive and sliding phase was decreased in the order of flutter>dolphin<TEX>$\geq$</TEX>side fin kick and tilting angle of trunk of the skilled was smaller than that of the unskilled in difference of maximum mean 7.97degree and minium mean 2.06degree. In summary of the above, It will desirable fin kick type because of more contribution to COG propulsion by the velocity & displacement in Y-axis and less fluid resistance by tilting angle of trunk and larger angular velocity in the case of more delayed in elapsed time of propulsive phase than that of the otherwise.

Optimal design approach for the plate-fin heat exchangers using neural networks cooperated with genetic algorithms

The paper demonstrates the successful application of genetic algorithm (GA) combined with back propagation neural networks (BP) for the optimal design of plate-fin heat exchangers (PFHE). The major objectives in the PFHE design are the minimum total weight and total annual cost for a given constrained conditions. The total weight target ensures an exchanger of the smallest size with minimum capital cost, whereas the annual cost target yields the optimum pressure drops accounting for the tradeoff between power consumption and heat exchanger weight. Total length and width of PFHE core, number of hot side layers, fin height and pitch on each side of PFHE are considered as variables to be optimized by means of GA combined with BP method. This optimization method of PFHE is universal and can be used for various PFHEs.

Observations of rough-toothed dolphins (Steno bredanensis) off the coast of Utila, Honduras

Local dive shop operators and fishermen report that rough-toothed dolphins (Steno bredanensis) are frequently encountered off the coast of Utila, Honduras, (16°05'46.5"N 86°55'47.8"W). Our observations suggest that at least some of these animals may constitute a resident population, although the extent of the resident group's home range has not been determined. Twenty-eight rough-toothed dolphins were identified using photo-identification techniques, 15 of which were re-sighted on two or more occasions. The 12 animals that were re-sighted four or more times were typically seen together, suggesting that they constitute a stable social group. At least one of these dolphins is an adult male, and his continued presence in this social group may reflect a social structure for rough-toothed dolphins that differs from that described for other dolphin species. Social interactions often involved tactile behaviours such as pectoral fin rubbing and side rubbing. The observed dolphins sometimes expressed interest in the research vessel and other boats by approaching, and on separate occasions examined a hydrophone and slow moving propeller visually and echoically. Overall, our behavioural observations suggest: (1) synchronous behaviours and ‘tight’ groupings are common while rough-toothed dolphins are travelling; (2) tactile contact is an important aspect of social interactions for rough-toothed dolphins; (3) cooperative behaviour occurs during play; and (4) rough-toothed dolphins are curious.

Bathyraja cousseauae sp.n.: A New Softnose Skate from the Southwestern Atlantic (Rajiformes, Rajidae)

A new species of softnose skate, Bathyraja cousseauae, is described from two adult and 19 juvenile specimens collected from different localities of the southwestern Atlantic. Bathyraja cousseauae is distinguished from all other southwestern Atlantic softnose skate species by its color pattern, squamation pattern of dorsal surface, lack of interspace between dorsal fins, and clasper morphology. The new species has a round pale area ocellus-like, margined with dark brown on posterior part of each pectoral base of dorsal surface, paler and dark spots over the disk, a continuous row of 21–27 median thorns from nuchal region to first dorsal fin and upper side of disc densely covered with dermal denticles. Males have rod-shaped claspers not expanded at proximal section of glans as it does in Bathyraja brachyurops. Besides the external morphological features, skeletal characteristics (neurocranium, scapulocoracoids, and claspers) are also described and illustrated here.

Wake dynamics and fluid forces of turning maneuvers in sunfish.

While experimental analyses of steady rectilinear locomotion in fishes are common, unsteady movement involving time-dependent variation in heading, speed and acceleration probably accounts for the greatest portion of the locomotor time budget. Turning maneuvers, in particular, are key elements of the unsteady locomotor repertoire of fishes and, by many species, are accomplished by generating asymmetrical forces with the pectoral fins. The development of such left-right asymmetries in force production is a critical and as yet unstudied aspect of aquatic locomotor dynamics. In this paper, we measure the fluid forces exerted by the left and right pectoral fins of bluegill sunfish (Lepomis macrochirus) during turning using digital particle image velocimetry (DPIV). DPIV allowed quantification of water velocity fields, and hence momentum, in the wake of the pectoral fins as sunfish executed turns; forces exerted during turning were compared with those generated by the immediately preceding fin beats during steady swimming. Sunfish generate the forces required for turning by modulating two variables: wake momentum and pectoral fin stroke timing. Fins on opposite sides of the fish play functionally distinct roles during turning maneuvers. The fin nearer the stimulus inducing the turn (i.e. the strong side fin) generates a laterally oriented vortex ring with a strong central jet whose associated lateral force is four times greater than that produced during steady swimming. Little posterior (thrust) force is generated by the strong-side fin, and this fin therefore acts to rotate the body away from the source of the stimulus. The contralateral (weak-side) fin generates a posteriorly oriented vortex ring with a thrust force nine times that produced by the fin during steady swimming. Minimal lateral force is exerted by the weak-side fin, and this fin therefore acts primarily to translate the body linearly away from the stimulus. Turning with the paired fins is not simply steady swimming performed unilaterally. Instead, turning involves asymmetrical fin movements and fluid forces that are distinct in both direction and magnitude from those used to swim forward at constant speed. These data reflect the plasticity of the teleost pectoral fin in performing a wide range of steady and unsteady locomotor tasks.

Experimental relationships for heat flux, nusselt number and temperature difference in a finned heater

In this study, a heater with finned surface, having a large application field in practice and working in accordance with the principle of natural convection heat transfer, is investigated. In such systems, the increase of heat transfer coefficient is obtained by preventing the rise of the thickness of the thermal layer using an obstacle on the heater surface and fins for widening the total surface. The temperature difference between the body-environment, and the heat transfer coefficients obtained from the heater change, depend on the fin parameters and heat flow applied on the system. In cylindrical heaters with circular fins and horizontal location, the vertical fluid flow on the side fin towards the outer surface increases the performance of the heater sufficiently. The results obtained from the experimental runs are shown in graphs depending on the distance between fins, the heater body diameter and the fin diameter.

Lateral aerodynamic interference between tanker and receiver in air-to-air refueling

Wind-tunnel data have been obtained from a tapered tanker wing and receiver aircraft model at varying vertical separation. The data are presented in derivative form and compared with theory using a flat vortex sheet model of the tanker wing wake to determine the induced angle-of-attack variation on the receiver wing, fin, and tailplane due to the tanker wing. Aerodynamic loads on the receiver are obtained by the vortex lattice method, with an allowance made for the vertical displacement of the tanker wake in the estimation of the fin side force. In the experiments, the lateral aerodynamic interference between tanker and receiver was determined by banking the tanker wing and displacing it sideways, and by yawing the receiver aircraft model. Data were obtained from open and closed test sections in order to assess the significant boundary interference effect and corrections estimated from the image vortex system of the tanker and receiver wings in the test section. In general, the theory compares favorably with the experimental data. The most significant terms are the rolling moments due to sideways and bank displacements. Significant side forces are produced due to sidewash on the fin from the tanker and receiver wings and, when displaced in yaw, the receiver experienced a loss in directional stability.

Laminar flow and heat transfer in a finned tube annulus

Laminar flow and heat transfer magnitudes in a finned tube annulus are obtained numerically. External circular fins on the inner tube are periodic. Pressure drop and heat transfer characteristics of the fins are obtained in the periodically fully developed region by varying geometric and flow parameters. Geometric parameters are annulus radius ratio (0.3 to 0.5), fin height/annular gap (0.33 to 0.67) and fin spacing/annular gap (2 to 5). Flow parameters are Reynolds number (100 to 1000) and Prandtl number (1 to 5). Comparisons are made with a plain tube annulus having the same length, heat transfer surface area, volume flow rate, and Reynolds number. The entire inter-fin space was found to be occupied by recirculating flow except at Reynolds numbers less than 500. A major contribution to heat transfer is made from the fin side at the downstream end. At Prandtl numbers less than 2, the use of fins may not be justified because the increase in pressure drop is more pronounced than the increase in heat transfer. At a Reynolds number of 1000 and A Prandtl number of 5, the heat transfer increases by a factor of 3.1, while the pressure drop increases by a factor of 2.3.

スリット無しのアルミニウムフィンチューブの曲げにおける塑性変形

Deformation of aluminum-fin tubes in uniform bending has been experimentally studied and compared with that of tubes without fin. When the plane of the fin is perpendicular to the bending plane, both the bending moment and the flattening of cross-section are identical with those in tubes without fin. But when the plane of the fin coincides with the bending plane, the bending moment and the flattening of cross-section become larger than those in ordinary tubes and wrinkles can be seen on the inner side fin. These effects of slittless fin on the deformation in bending are quantitatively clarified.

Optimal heat pipe heat exchanger design

A typical heat pipe heat exchanger with continuous planar fins and a staggered equilateral triangular pitch of the tubes is subject to optimization from the point of view of the ratio heat flow/weight and heat transfer effectiveness. Different optimization procedures are explained in detail and numerical results are given in the application. The procedures are as follows. 1. A. If hot and cold fluid mass flow velocities in the minimum free flow areas are given, one obtains the maximum of the ratio heat flow, Q /mass, M for optimal values of fin density and equilateral triangular pitch. The ratio of evaporator to condenser lengths observes a relation which allows Q/M to be permanently at its peak with respect to the dimensionless saturation temperature. 2. B.1. One obtains the maximum of the ratio heat flow/evaporator mass for optimal fin and triangular pitches. 2. One selects the cold fluid mass flow velocity G 2 so as to obtain equality between evaporator and condenser fin side heat transfer coefficients. The optimal pitches found at the evaporator also lead to the maximum of heat flow/condenser mass. 3. There is an optimal value of the ratio of evaporator to condenser lengths which ensures Q/M to be a maximum with respect to the dimensionless saturation temperature. 3. C.1. As B.1.2. G 2 remains variable. A condenser with maximal heat exchanger heat transfer effectiveness is “linked” to the optimized evaporator. One obtains the ratio of evaporator to condenser lengths and the ratio of hot and cold fluid heat capacities as optimal functions of G 2 . 4. D.1. As B.1.2. G 2 remains variable. The ratio of evaporator to condenser lengths is selected from the condition: Q/M maximum with respect to the dimensionless saturation temperature. It follows that this ratio becomes an optimal function of G 2 . The ratio of the heat capacities is derived as an optimal function of G 2 too. The heat flow value, the number of tubes in a row and the number of rows do not affect optimization results. The optimization procedures presented in this paper may be used, with adequate transformations, for other heat pipe heat exchanger configurations.

Improved formulations for the analysis of convecting and radiating finned surfaces

The study of the heat flow within finned surfaces involving combined convective and radiative heat dissipation is conventionally based upon unidirectional analyses with attention restricted solely to the fin side. In this study the heat conduction within the interface to which the fins are attached, and the heat transfer from the unfinned side of this interface are also considered. The general situation in which the fins and the base surface have different thermal conductivities and different surface emissivities is examined. Fin-to-base-surface, fin-toenvironment, fin-to-fin, and base-surface-to-environment radiant interactions are all accounted for, but the convective fluids are assumed to be radiatively transparent. Oneand two-dimensional formulations are developed for analyzing the heat flow. These represent a major extension of the previously employed formulations. The results obtained indicate, in particular, that the previously employed formulations are inadequate for the effective design of finned heat exchangers.

Analysis and Design of Efficient Absorbers for Low-Temperature Desiccant Air Conditioners

Desiccant dehumidification and air-conditioning systems require careful design to minimize large parasitic power requirements for pumps and blowers. Each component depends to some extent on overall system characteristics, yet each component must be carefully modeled in itself. The most challenging part of optimizing a system is the absorber design. In order to increase the heat and mass transfer rate while minimizing the pressure loss in the absorber, a direct contact falling film fin-tube heat exchanger is analyzed with water flowing on the tube side and desiccant flowing as a falling film on the fin side. Air is cooled and dehumidified by the water and desiccant as it is circulated through the absorber. A model to analyze the heat and mass transfer in the absorber has been developed. An optimum design has been selected based on not only thermal performance but also practical and economic considerations. Application of the absorber design is then made to design of a complete desiccant system for use with low-temperature heat as an energy source.

Fin Induced Laminar Interactions on Sharp and Spherically Blunted Cones

The flowfield structure (surface streamlines and shock patterns), and pressure and heat-transfer distributions associated with small fins mounted near the base of a 7° half-angle cone are measured. The tests are conducted in a hypersonic freestream at a Mach number of 10, freestream unit Reynolds numbers of 0.12 and 0.6 x 10 6/ foot, and wall to total temperature ratio of 0.27. Vehicle geometry (nose bluntness, and fin sweep, shape, thickness, and cant) and orientation (angles of attack and roll) are systematically varied. Fin leading-edge pressure and heat transfer agree with swept infinite cylinder predictions; fin side heating agrees with blunt swept slab theory. Flow patterns, heating and pressure in the fin-cone region are characteristic of corner flow geometries.

Fins

Judging by the number of present-day aircraft which have suffered changes of fin shape, it is clear that there is still some difficulty in estimating the size and shape of fin required on a new project. In this paper some of the principles on which fin design is based will be explained, and some of the difficulties involved described.It is necessary to have some sort of fin to provide weathercock, or directional, stability. This is illustrated in Fig. 1. This shows the balance of yawing moments, due to sideslipping. In general, the side force acting on the fuselage, represented by the black arrow, has its c.p. ahead of the e.g. of the aircraft, and hence it produces a destabilising moment about the e.g. Sufficient fin area must be provided for the yawing moment due to the fin side force, represented by the white arrow, to at least equal the destabilising fuselage moment. Otherwise, when disturbed laterally due to, say, a gust, the aeroplane will tend to swing still further out of wind, making it difficult to fly accurately. The minimum permissible fin area can, in fact, be fixed simply by this requirement for weathercock stability.