3,360 research outputs found

    Wave Run-Up Phenomenon on Offshore Platforms: Part 1. Tension Leg Platform

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    This study reports on an extensive experimental campaign carried out to evaluate non-linear waves applied to offshore structures in extreme marine environments. An offshore tension leg platform (TLP) model was used to observe the waves around a fixed-type offshore structure. The wave amplitude measured in the experiments of this study was indicated as a wave run-up ratio. Both the first-order analysis and the analysis of the entire wave amplitude were described. The experimental results were compared with the calculations from a potential-based code in order to verify the effectiveness of the developed technology

    Prediction for Irregular Ocean Wave and Floating Body Motion by Regularization: Part 1. Irregular Wave Prediction

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    Ocean waves can be explained in terms of many factors, including wave spectrum, which has the characteristics of wave height and periodicity, directional spreading function, which has a directional property, and random phase, which randomly represents a certain property. Under the assumption of a linear system, ocean waves show irregular behaviours, which can be observed in the forms of wave spectrum, directional spreading function, and complex phase calculations using the method of linear superposition. Ocean waves, which include a variety of periodic elements, exhibit direct proportionality between their period and propagation velocity. The purpose of this study was to understand the phase components of the period and to make exact calculations on the deterministic phase in order to make predictions on ocean waves. However, measurements of actual ocean waves exist only in the form of information on wave elevation, so we faced an inverse problem of having to analyse this information and calculate the deterministic phase. Regularization was used as part of the solution, and various methods were used to obtain stable values

    Prediction for Irregular Ocean Wave and Floating Body Motion by Regularization: Part 2. Motion Prediction

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    In the analysis of the motion of a floating body, the domains can broadly be divided into the frequency domain and the time domain. The essence of the frequency domain analysis lies in calculating the hydrodynamic coefficient from the equation of motion, which has six degrees of freedom, by applying several methods. In this research, Bureau Veritas’s “HydroStar” software was used, and the comparison and the verification were carried out by experiments. For the time domain analysis, we used an existing method proposed by Cummins and made motion predictions by using deterministic random phases calculated in the time domain calculations of the excitation force. Lastly, the potential of wave and motion predictions was verified through the data obtained from a motion analysis experiment using a tension leg platform in the context of irregular waves

    Ultra LILI-ideals in lattice implication algebras

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    summary:We define an ultra LILI-ideal of a lattice implication algebra and give equivalent conditions for an LILI-ideal to be ultra. We show that every subset of a lattice implication algebra which has the finite additive property can be extended to an ultra LILI-ideal

    Ordered homomorphisms and kernels of ordered BCI-algebras

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    Recently Yang-Roh-Jun introduced the notion of ordered BCI-algebras as a generalization of BCI-algebras. They also introduced the notions of homomorphisms and kernels of ordered BCI-algebras and investigated related properties. Here we extend their investigation to ordered homomorphisms, i.e., order-preserving homomorphisms. To this end, the notions of ordered homomorphism and kernel of ordered BCI-algebras are first defined. Next, properties associated with (ordered) subalgebras, (ordered) filters and direct products of ordered BCI-algebras are addressed

    REMOTE SENSING OF WAVE DIRECTIONALITY BY TWO-DIMENSIONAL DIRECTIONAL WAVELETS: PART 1. THE DETECTION TOOLS OF DIRECTIONALITY IN SIGNALS

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    This paper presents the results of a study investigating methods of wave directionality based on wavelet transform. In part 1 of this paper, the theoretical background and characteristics of directional wavelet were discussed. Morlet wavelet and Cauchy wavelet were examined to test their efficiency in detection of directionality in signals. These wavelets were tested on numerical images which were considered to describe the basic characteristics of directionality of ocean waves
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