7,420 research outputs found
On exact solutions to the euclidean bottleneck steiner tree problem
Full text linkWork by S.W. Bae was supported by the Brain Korea 21 Project. Work by C. Lee and
S. Choi was supported by the Korea Science and Engineering Foundation (KOSEF)
grant funded by the Korea government (MOST) (No. R01-2007-000-20865-0)
Development of high performance composite bend-twist coupled blades for a horizontal axis tidal turbine
No full textDevelopment of a design methodology for a composite, bend-twist coupled, tidal turbine blade has been undertaken. Numerical modelling was used to predict the response of the main structural member for the adaptive blade. An experimental method for validation is described. The analysis indicates a non-linear blade twist response
Determination of Thermal Response on Mold Surface and Recommendation of Feasible Heating Time and Gas Flow Rate for a Circular Cavity by Gas Preheating
No full textAnalysis of Fan-induced Convective Heat Transfer Encountered in Electronic Equipment Cooling
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A method for analysing fluid structure interactions on a horizontal axis tidal turbine
No full textFree stream tidal turbines are rotating bodies in fast flowing tidal currents, and as such are exposed to fluctuating loads from the surrounding fluid. These time varying forces will cause the blades to deform dynamically, potentially deflecting the blade shape away from the optimum orientation as well as exciting resonant responses that may enhance fatigue loading. It is important to understand this hydroelastic response for all but the stiffest blades. A loosely coupled, modular approach to fluid structural interactions (FSI) has been developed for the analysis of horizontal axis tidal turbine blades (HATTs). This paper discusses the methodology behind the FSI process and illustrates the technique through a case study of a 20m diameter, three bladed, horizontal axis tidal turbine, in which the deflection of the blades is examined through the iterative procedure
Performance prediction of a free stream tidal turbine with composite bend-twist coupled blades
No full textFree stream tidal turbines are a source of growing interest in the marine renewable energy field. Some designs use variable pitch blade control devices in order to maximize the efficiency of the turbines; however these are complex to design, construct and maintain under the severe load conditions sub sea devices experience.
There is an interest in the use of composite materials for potential improvements in hydrodynamic and structural performance of Horizontal Axis Tidal Turbines (HATT). In addition to the advantages of high strength-to-mass and high strength to stiffness ratios, anisotropy of the laminated fibre composites can be designed to allow 3D tailoring of the blade deformation. Anisotropic structures show different levels of elastic coupling, depending on the ply angle in the layers that comprise such a material. Passive control of a turbine blade can be achieved by taking advantage of the directionality of the anisotropic composite material.
A structure that undergoes both bending and twisting due to a pure bending load is said to exhibit bend-twist coupling. This type of behaviour has been identified as a potential method for load reduction - particularly fatigue loads, and an increase in both efficiency and annual energy capture in wind turbines [1]. Preliminary studies have since shown that this may also be the case for HATTs [2].
A computationally efficient, yet realistic, model has been developed in order to estimate the amount of induced twist present on a bend-twist coupled blade in a tidal stream. This model takes into account the effect on the induced twist of fibre orientation, blade loading and cross section, material mechanical properties, and shell thickness. The method has been incorporated into a Blade Element Momentum code, modified to predict the performance of free stream tidal devices; such that the performance of a HATT with composite bend-twist coupled blades could be estimated.
It has been shown that, when compared to a free stream tidal turbine with fixed blades of a similar configuration, a HATT that utilises composite bend-twist couple blades can reduced fatigue loading, bring the turbine efficiency closer to the Betz limit and increase the annual energy capture
Metabolic control analysis of various dynamic behaviors of biochemical systems
No full textMetabolic control analysis is a useful tool to understand and predict the dynamic behaviors of biochemical systems. While the classical metabolic control coefficients are defined only for the systems with steady-state trajectories, many important dynamic behaviors do not reach the steady-state, but show the oscillatory or irregular behaviors. This study proposes the investigation scheme for metabolic control analysis of the every dynamic system regardless of the existence of steady-state, by classifying the systems into three groups: the systems with steady-state trajectories, autonomously oscillating systems and the other systems with irregular behaviors
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