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Статті в журналах з теми "Regular wave generation"
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Gomes, M. N., C. R. Olinto, L. A. O. Rocha, J. A. Souza, and L. A. Isoldi. "COMPUTATIONAL MODELING OF A REGULAR WAVE TANK." Revista de Engenharia Térmica 8, no. 1 (June 30, 2009): 44. http://dx.doi.org/10.5380/reterm.v8i1.61881.
Повний текст джерелаАнотація:
This paper presents two different numerical methodologies to generate regular gravity waves in a wave tank. We performed numerical simulations of wave generation through the FLUENT® package, using the Volume of Fluid (VOF) multiphase model to reproduce the wave propagation in the tank. Thus it was possible to analyze two methods for generating regular waves that could be used in future work, especially in the study of devices of energy conversion from ocean waves into electrical energy.
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Eldrup, Mads Røge, and Thomas Lykke Andersen. "Applicability of Nonlinear Wavemaker Theory." Journal of Marine Science and Engineering 7, no. 1 (January 14, 2019): 14. http://dx.doi.org/10.3390/jmse7010014.
Повний текст джерелаАнотація:
Generation of high-quality waves is essential when making numerical or physically model tests. When using a wavemaker theory outside the validity area, spurious waves are generated. In order to investigate the validity of different wave generation methods, new model test results are presented where linear and nonlinear wave generation theories are tested on regular and irregular waves. A simple modification to the second-order wavemaker theory is presented, which significantly reduces the generation of spurious waves when used outside its range of applicability. For highly nonlinear regular waves, only the ad-hoc unified wave generation based on stream function wave theory was found acceptable. For irregular waves, similar conclusions are drawn, but the modified second-order wavemaker method is more relevant. This is because the ad-hoc unified generation method for irregular waves requires the wave kinematics to be calculated by a numerical model, which might be quite time-consuming. Finally, a table is presented with the range of applicability for each wavemaker method for regular and irregular waves.
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Wang, Gang, and Jin-Hai Zheng. "SUBHARMONIC GENERATION OF TRANSVERSE OSCILLATIONS INDUCED BY INCIDENT REGULAR WAVES." Coastal Engineering Proceedings 1, no. 33 (September 27, 2012): 11. http://dx.doi.org/10.9753/icce.v33.waves.11.
Повний текст джерелаАнотація:
It is generally accepted that there are transverse oscillation, which are concentrated and confined to the backwall and decay asymptotically offshore, existed in the harbor of constant slope, however, whether these oscillations can be induced by the normally incident waves is not clear. This numerical investigation aims at providing the subharmonic generations of transverse oscillations within the harbor of a plane slope by waves normally impacting on. For the harbor of perfectly plane slopes, the subharmonic transverse oscillations are small on the mild and moderate slopes but evident on the steep slope. This instability can take place only if the incident wave amplitude exceeds a threshold value, and transverse oscillations can even grow up to a larger value than that of longitudinal oscillations. The magnitudes of transverse oscillations are approximately the same, only their growth rates are affected by the incident wave amplitude.
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Vasarmidis, Panagiotis, Vasiliki Stratigaki, Tomohiro Suzuki, Marcel Zijlema, and Peter Troch. "Internal Wave Generation in a Non-Hydrostatic Wave Model." Water 11, no. 5 (May 10, 2019): 986. http://dx.doi.org/10.3390/w11050986.
Повний текст джерелаАнотація:
In this work, internal wave generation techniques are developed in an open source non-hydrostatic wave model (Simulating WAves till SHore, SWASH) for accurate generation of regular and irregular long-crested waves. Two different internal wave generation techniques are examined: a source term addition method where additional surface elevation is added to the calculated surface elevation in a specific location in the domain and a spatially distributed source function where a spatially distributed mass is added in the continuity equation. These internal wave generation techniques in combination with numerical wave absorbing sponge layers are proposed as an alternative to the weakly reflective wave generation boundary to avoid re-reflections in case of dispersive and directional waves. The implemented techniques are validated against analytical solutions and experimental data including water surface elevations, orbital velocities, frequency spectra and wave heights. The numerical results show a very good agreement with the analytical solution and the experimental data indicating that SWASH with the addition of the proposed internal wave generation technique can be used to study coastal areas and wave energy converter (WEC) farms even under highly dispersive and directional waves without any spurious reflection from the wave generator.
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Klein, Marco, Moritz Hartmann, and Franz von Bock und von Bock und Polach. "Note on the Application of Transient Wave Packets for Wave–Ice Interaction Experiments." Water 13, no. 12 (June 19, 2021): 1699. http://dx.doi.org/10.3390/w13121699.
Повний текст джерелаАнотація:
This paper presents the transient wave packet (TWP) technique as an efficient method for wave–ice interaction experiments. TWPs are deterministic wave groups, where both the amplitude spectrum and the associated phases are tailor-made and manipulated, being well established for efficient wave–structure interaction experiments. One major benefit of TWPs is the possibility to determine the response amplitude operator (RAO) of a structure in a single test run compared to the classical approach by investigating regular waves of different wave lengths. Thus, applying TWPs for wave–ice interaction offers the determination of the RAO of the ice at specific locations. In this context, the determination of RAO means that the ice characteristics in terms of wave damping over a wide frequency range are obtained. Besides this, the wave dispersion of the underlying wave components of the TWP can be additionally investigated between the specific locations with the same single test run. For the purpose of this study, experiments in an ice tank, capable of generating tailored waves, were performed with a solid ice sheet. Besides the generation of one TWP, regular waves of different wave lengths were generated as a reference to validate the TWP results for specific wave periods. It is shown that the TWP technique is not only applicable for wave–ice interaction investigations, but is also an efficient alternative to investigations with regular waves.
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Zhang, Huichen, and Markus Brühl. "GENERATION OF EXTREME TRANSIENT WAVES IN EXPERIMENTAL MODELS." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 51. http://dx.doi.org/10.9753/icce.v36.waves.51.
Повний текст джерелаАнотація:
The transfer of natural waves and sea states into small- and large-scale model teste contributes to the proper design of offshore and coastal structure. Such shallow-water ocean surface waves are highly nonlinear and subject to wave transformation and nonlinear wave-wave interactions. However, the standard methods of wave generation according to conventional wave theories and wave analysis methods are limited to simple regular waves, simple sea states and low-order wave generation without considering the nonlinear wave-wave interactions. The research project Generation of Extreme Transient Waves in Experimental Models (ExTraWaG) aims to accurately generate target transient wave profile at a pre-defined position in the wave flume (transfer point) under shallow water conditions. For this purpose, the KdV-based nonlinear Fourier transform is introduced as a continuative wave analysis method and is applied to investigate the nonlinear spectral character of experimental wave data. Furthermore, the method is applied to generate transient nonlinear waves as specific locations in the wave flume, considering the nonlinear transformation and interactions of the propagating waves.
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Jung, Jae-Sang, and Changhoon Lee. "An Analytical Study of Regular Waves Generated by Bottom Wave Makers in a 3-Dimensional Wave Basin." Journal of Korean Society of Coastal and Ocean Engineers 34, no. 4 (August 31, 2022): 93–99. http://dx.doi.org/10.9765/kscoe.2022.34.4.93.
Повний текст джерелаАнотація:
Analytical solutions for regular waves generated by bottom wave makers in a 3-dimensional wave basin were derived in this study. Bottom wave makers which have triangular, rectangular and combination of two shapes were adopted. The 3-dimensional velocity potential was derived based on the linear wave theory with the bottom moving boundary condition, kinematic and dynamic free surface boundary conditions in a wave basin. Then, analytical solutions of 3-dimensional particle velocities and free surface displacement were derived from the velocity potential. The solutions showed physically valid results for regular waves generated by bottom wave makers in a wave basin. The analytical solution for obliquely propagating wave generation from bottom wave maker which works like a snake was also derived. Numerical results of the solution agree well with theoretically predicted results.
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Ali Shehab Shams Eldeen, Ahmed M. R. El-Baz, and Abdalla Mostafa Elmarhomy. "CFD Modeling of Regular and Irregular Waves Generated by Flap Type Wave Maker." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 85, no. 2 (August 9, 2021): 128–44. http://dx.doi.org/10.37934/arfmts.85.2.128144.
Повний текст джерелаАнотація:
The improvement of wave generation in numerical tanks represents the key factor in ocean engineering development to save time and effort in research concerned with wave energy conversion. For this purpose, this paper introduces a numerical simulation method to generate both regular and irregular waves using Flap-Type wave maker. A 2D numerical wave tank model is constructed with a numerical beach technique, the independence of the numerical beach slope is tested to reduce the wave reflections. The different governing parameters of the Flap type wave maker were studied such as periodic time dependency and length of the flap stroke. The linear wave generated was validated against the wave maker theory WMT, the numerical results agreed with WMT. The Pierson-Moskowitz model is used to generate irregular waves with different frequencies and amplitudes. The numerical model succeeded to generate irregular waves which was validated against published experimental data and with Pierson-Moskowitz spectrum model using Fourier expansion theory in the frequency domain. Useful results are presented in this paper based on the numerical simulation to understand the characteristics of the waves. This paper produces a full guide to generate both regular and irregular waves numerically using ANSYS-CFX approach to solve the 2D Unsteady Reynolds Averaged Navier-Stokes Equation (URANS).
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Naeser, Harald. "The Capillary Waves’ Contribution to Wind-Wave Generation." Fluids 7, no. 2 (February 10, 2022): 73. http://dx.doi.org/10.3390/fluids7020073.
Повний текст джерелаАнотація:
Published theories and observations have shown that dissipation of gravity waves implies frequency downshifting of wave energy. Hence, for wind-waves, the wind energy input to the highest frequencies is of special interest. Here it is shown that this input is vital, because the direct wind energy input obtained by the air-pressure’s work on most gravity waves is slightly less than what the waves need to grow. Further, the wind’s input of the angular momentum that waves need to grow is found to be absent at most gravity wave frequencies. The capillary waves that appear at the surface of the sea when the wind is blowing solve these problems. To demonstrate this, an extension of linear wave theory is established to study possibilities and limitations for transfer of energy and angular momentum from the wind to waves through these frequencies. The theory describes regular, gravity–capillary waves with constant amplitude under laminar conditions. It includes surface tensions, viscosity, gravity and a wind-generated shear current, and shows that these waves—contrary to most gravity waves—receive more energy from the wind than they dissipate and angular momentum they cannot keep. Hence, the problem of the missing input of energy and angular momentum from wind to gravity waves is solved by transfers through the capillary waves. This implies that capillary waves are vital to obtain growing gravity waves.
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Liu, Yi, Yuxi Zheng, Ruiyin Song, Junhua Chen, and Heng Jin. "Wave generation characteristic analysis of piston and flap type wave maker with rotary-valve-control vibrator." Journal of Vibration and Control 26, no. 15-16 (January 9, 2020): 1297–308. http://dx.doi.org/10.1177/1077546319895664.
Повний текст джерелаАнотація:
Wave maker is one of the most important experimental equipment in marine engineering. To meet the demands of simulation of higher wave amplitude and compare the effect of piston and flap type wave generation, a new wave generation device was proposed and a new piston and flap type wave maker with a rotary-valve-control vibrator was developed. A mathematical model of the new wave maker was established and analysed by Simulink, and a series of experiments were conducted on the wave maker to analyze wave generation characteristics. The results show that the wave maker can adjust the distance of wave paddle and generate different regular waves. The bigger the axial opening size of the valve port, the larger the wave paddle amplitude and the wave amplitude; the higher the pressure, the higher the wave paddle amplitude and the wave amplitude. High frequency wave making is more efficient than the lower one, and piston type wave making is more efficient than those wave makers that generate waves by flap type.
Дисертації з теми "Regular wave generation"
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Descamps, Théo. "Numerical analysis and development of accurate models in a CFD solver dedicated to naval applications with waves." Thesis, Ecole centrale de Nantes, 2022. http://www.theses.fr/2022ECDN0049.
Повний текст джерелаАнотація:
L’objectif de cette thèse est de développer des solveurs numériques et des méthodologies afin d’améliorer le temps de calcul et la précision des simulations de tenue à la mer et de résistance ajoutée sur houle. Tout d’abord, une synthèse de l’algorithme du solver foamStar développé en interne est effectuée. A partir de cette analyse, une modification est proposée afin de pouvoir utiliser le "Multidimensional Universal Limiterfor Explicit Solution" (MULES) avec un schéma temporel backward d’ordre deux. Ensuite, plusieurs études successives sont réalisées afin de : vérifier l’implémentation du schéma backward ; définir une configuration numérique et des maillages efficaces pour la simulation de houle. Les cas d’étude sont : les tourbillons de Taylor-Green, la houle régulière non linéaire se propageant dans un domaine periodique, et enfin, la houle régulière générée avec des zones de relaxation et des configurations numériques proches de celles utilisées pour des applications navales. Dans la dernière partie de cette thèse, une étude préliminaire est réalisée en simulant un porte-conteneur avec une vitesse d’avance dans des houles régulières de face. Les recommandations définies tout au long de cette thèse sont également évaluéesThe objective of the present thesis is to develop solvers and methodologies in order to improve the computational cost andthe accuracy with regard to the thematics of seakeeping and added resistance. First, a synthetic workflow of the algorithmof the in-house solver foamStar is proposed. From this analysis a modification is proposed in order to use the Multidimensional Universal Limiter for Explicit Solution (MULES) with a second-order backward time scheme. Then, successive studies are done in order to: verify the implementation of the backward scheme; define an efficient numerical set-up and adequate mesh structures for numerical wave simulations. The case studies are, Taylor-Green vortices, nonlinear regular wave propagating in a periodic domain, and finally, regular waves generated with relaxation zones considering numerical configurations close to what is used for naval applications. In the last part of this Thesis, a preliminary study is done simulating a containership with forward speed in head regular waves. The recommendations derived all along this thesis are also evaluated
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Gireli, Tiago Zenker. "Modelação física em canal da geração de ondas regulares e irregulares para estudo de quebra-mar de enrocamento." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3147/tde-01042008-093100/.
Повний текст джерелаАнотація:
Tendo em vista a importância das obras portuárias e costeiras no desenvolvimento do país e a complexidade dos fenômenos que regem os Processos Litorâneos, torna-se relevante a utilização de modelos físicos, como os canais de ondas, para otimização destes projetos. Neste sentido, os principais objetivos desta Tese são o desenvolvimento de um sistema de controle para o gerador de ondas do Laboratório de Hidráulica da Escola Politécnica da Universidade de São Paulo - LHEPUSP, capaz de gerar ondas irregulares, baseadas em espectros de energia da agitação, bem como, a partir de um estudo com caso de um molhe de berma, avaliar do ponto de vista técnico o procedimento de dimensionamento de quebra-mares com base no ensaio da estrutura frente a ondas regulares com as características da onda significativa de projeto. Uma das contribuições desta Tese é o novo sistema de controle da geração de ondas do LHEPUSP, que é capaz de gerar ondas regulares, irregulares e randômicas. A outra contribuição, referente ao estudo de caso, permitiu concluir que o emprego de ondas regulares na otimização em modelo físico de projetos de quebra-mares pode levar a dimensionamentos conservadores, e portanto de custo mais alto, principalmente no dimensionamento de obras dispostas em profundidades inferiores aos 10 m, onde foram encontradas diferenças para mais no recuo da estrutura, comparativamente com a ação de ondas irregulares de mesma altura significativa.Considering the harbour and coastal structures significance for the Country development and the complex Littoral Processes phenomena, is an important requirement the physical models use, like wave flumes, to improve these designs. Following this context, the Thesis main purposes are to develop a wave maker control system for the Laboratório de Hidráulica da Escola Politécnica da Universidade de São Paulo - LHEPUSP wave fume able to generate irregular waves, based on wave energy spectra, and also, from a berm jetty case study, evaluate, from the technical point of view, the breakwater design procedure based on structure tests with design significative regular waves. One of the Thesis contribution is the new wave maker control system for the LHEPUSP wave fume able to generate regular, irregular and randomic waves. The other contribution, about the case study, showed as conclusion that the regular waves use for breakwaters design physical model improvement may suggest conservative results, inducing high cost structures, mainly for those ones in depths lower than 10 m, being observed larger structural backward response differences, comparing with irregular waves action with the same significative height.
Книги з теми "Regular wave generation"
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Rondinone, Troy. “The Regular Friday Coaxial Bloodbath”. University of Illinois Press, 2017. http://dx.doi.org/10.5406/illinois/9780252037375.003.0003.
Повний текст джерелаАнотація:
This chapter discusses the historical and cultural factors that shaped the rise of TV boxing. It suggests that Cold War hypermasculinity combined with lived war memories to provided a potent cultural milieu in which boxing found a comfortable place. Though it is difficult to prove that war “made” TV boxing popular, a few facts suggest linkages. This was truly a generation of soldiers. An astounding 80 percent of the men born in the 1920s became veterans. It is entirely possible that this unprecedented wave of warriors coincided with the absolute height of boxing viewing in America is sheer coincidence. But this fact, combined with much anecdotal evidence and a cultural backdrop of gunslinging violence, indicates a connection. Whether it was the cover story of Life magazine featuring a five-year-old “fleaweight” boxer, the enthusiastic core of veterans who watched the fights, or the ongoing dialogue about women and the “caveman” allure, boxing and war experience cannot easily be separated.
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Zagare, Frank C., and Branislav L. Slantchev. Game Theory and Other Modeling Approaches. Oxford University Press, 2018. http://dx.doi.org/10.1093/acrefore/9780190846626.013.401.
Повний текст джерелаАнотація:
Game theory is the science of interactive decision making. It has been used in the field of international relations (IR) for over 50 years. Almost all of the early applications of game theory in international relations drew upon the theory of zero-sum games, but the first generation of applications was also developed during the most intense period of the Cold War. The theoretical foundations for the second wave of the game theory literature in international relations were laid by a mathematician, John Nash, a co-recipient of the 1994 Nobel Prize in economics. His major achievement was to generalize the minimax solution which emerged from the first wave. The result is the now famous Nash equilibrium—the accepted measure of rational behavior in strategic form games. During the third wave, from roughly the early to mid-1980s to the mid-1990s, there was a distinct move away from static strategic form games toward dynamic games depicted in extensive form. The assumption of complete information also fell by the wayside; games of incomplete information became the norm. Technical refinements of Nash’s equilibrium concept both encouraged and facilitated these important developments. In the fourth and final wave, which can be dated, roughly, from around the middle of the 1990s, extensive form games of incomplete information appeared regularly in the strategic literature. The fourth wave is a period in which game theory was no longer considered a niche methodology, having finally emerged as a mainstream theoretical tool.
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Wu, Yung-Hsing. Closely, Consciously Reading Feminism. University of Illinois Press, 2017. http://dx.doi.org/10.5406/illinois/9780252039805.003.0005.
Повний текст джерелаАнотація:
This chapter considers the fate of close reading in second-wave reading and writing communities, through an analysis of memoirs, literary criticism, and a novel, Marilyn French's The Women's Room. It argues that just as feminist consciousness-raising believed that reading could generate closeness among women, and just as feminist fiction of the 1970s was regularly cited (and decried) for an intimacy of identification it was said to create for women readers, early feminist literary criticism was marked by an investment in the political promise of closeness. For feminist literary critics of that first academic generation, this sensibility marked a shift from closeness described as a familiar stance toward textuality to one with distinctive affective and political valences. In other words, this sensibility yoked the question of women reading to consciousness: to its nascence, whether sudden or gradual, and to its qualities of strangeness, pain, even joy. While their assumptions led them to find reading in very different places, their critical desires stemmed from the shared view that reading, wherever it is found, can be a place for politics.
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Jones, Michael, Norman Qureshi, and Kim Rajappan. Atrial flutter. Edited by Patrick Davey and David Sprigings. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780199568741.003.0117.
Повний текст джерелаАнотація:
Atrial flutter is the term given to one of the four types of supraventricular tachycardia; in it, atrial activation occurs as a consequence of a continuous ‘short circuit’: a defined and fixed anatomical route, resulting in a fairly uniform atrial rate, and uniform atrial flutter waves on the ECG. The ventricles are not a part of this arrhythmia circuit, and ventricular activation is variable, dependent on atrioventricular (AV) nodal conduction. Given that the atrial rate is essentially uniform (e.g. 300 min−1), ventricular activation tends to be regular (i.e. 150 min−1, 100 min−1, 75 min−1, etc., if the atrial rate is 300 mins−1), or regularly irregular if changes are occurring in the fraction of conducted impulses to the ventricles. When AV nodal conduction permits only 4:1 conduction or less, atrial flutter is usually obvious, but when ventricular rates are higher (150 min−1 or more) the flutter waves can be obscured by the QRS complexes, making diagnosis more difficult. Atrial flutter is of two types, typical and atypical. Typical atrial flutter is a right atrial tachycardia, with electrical activation proceeding around the tricuspid valve annulus. This arrhythmia is dependent on a zone of slow electrical conduction through the cavotricuspid isthmus (the tissue lying between the origin of the inferior vena cava and the posterior tricuspid valve). The resulting circuit can be either anticlockwise (activation proceeds up the inter-atrial septum, across the atrial roof, down the free wall, and then through the cavotricuspid isthmus to the basal septum) or clockwise (down the inter-atrial septum and around the circuit in the opposite direction). Anticlockwise typical atrial flutter is more common. Atypical atrial flutter refers to all other atrial flutters, and this includes other right atrial flutters (e.g. pericristal flutter), left atrial flutters, post-ablation or post-surgical flutters, and pulmonary vein flutters. The feature common to all types of flutter and which differentiates flutter from other types of supraventricular tachycardia is the presence of a macro-re-entrant anatomical circuit around which the electrical impulse travels continuously and repeatedly, thereby generating the flutter. Even though typical atrial flutter has a fairly obvious and specific appearance on the ECG, atypical flutters do not, and often it is only possible to differentiate atypical flutter from atrial tachycardias by invasive electrophysiology studies, as the ECG alone may be insufficient.
Частини книг з теми "Regular wave generation"
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Winseck, Dwayne. "The Broken Internet and Platform Regulation: Promises and Perils." In Palgrave Global Media Policy and Business, 229–57. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-95220-4_12.
Повний текст джерелаАнотація:
AbstractA relatively small number of global Internet giants—Google, Apple, Facebook, Amazon, Microsoft, and Netflix—have come under intense and ongoing fire for precipitating a twin crisis of journalism and the media, destroying democracy, and centralizing control over the Internet. In response, a new wave of Internet regulation is now in the making in one country after another. This chapter agrees that a forceful response to the platforms is overdue but raises concerns that the case against GAFAM + has become orthodoxy, anchored in cherry-picked evidence and a tendency to see these firms as the cause of all perceived woes. I also argue that while attempts to regulate digital platforms by the standards of broadcasting regulation may be politically expedient, this approach rests on superficial analogies. It also ignores the fact that the media industries have developed in close proximity to the vastly larger telecoms, consumer electronics and banking firms since the mid-nineteenth century. The last sections of this chapter offer four principles of structural and behavioural regulation drawn from this history as guides for a new generation of internet regulation today: structural separation (break-ups), line of business restrictions (firewalls), public obligations and public alternatives.
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Strasser, Ulrike. "Braving the Waves with Francis Xavier." In Missionary Men in the Early Modern World. Nieuwe Prinsengracht 89 1018 VR Amsterdam Nederland: Amsterdam University Press, 2020. http://dx.doi.org/10.5117/9789462986305_ch02.
Повний текст джерелаАнотація:
This chapter discusses the transoceanic voyage as a rite de passage into missionary manhood. Jesuits defined their brand of masculinity in the social microcosm of the ship, carrying out pastoral work in confinement and danger. If Ignatius was the Society’s inventor and Ur-father, Francis Xavier was its patron of mobility and a model for conduct for generations of missionaries, including many Germans. Hagiographical accounts and paintings of Xavier’s dramatic sea voyages emphasize his exemplary self-governance and ability to convert sinful fears into correct fear of God. The transoceanic ship was a site of embodied conditioning for those who followed in Xavier’s footsteps. When the missionaries reached foreign shores, they felt more ready than ever to convert and regulate indigenous others.
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Fehr, Hans, and Fabian Kindermann. "Extending the OLG model." In Introduction to Computational Economics Using Fortran. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198804390.003.0011.
Повний текст джерелаАнотація:
In Chapter 6 we used our basic OLG model to discuss the welfare and efficiency effects of various policy reforms. Of course, we have to be cautious in drawing robust conclusions fromsuch a policy analysis. In the basic model households only decide on their intertemporal consumption allocation. Hence, public policy solely distorts the savings decision and, consequently, most of the policy reforms hardly impact on economic efficiency but only redistribute across cohorts. Our analysis could be much more instructive when decisions of economic agents are multidimensional, so that various distortions induced by public policy interact. In this chapter we therefore introduce an extended individual decision process. Households not only decide on their savings, but also on their time use. Given a specific time endowment (say a day or a year), agents can either work in the market (and earn income), go to school (and acquire human capital for future income generation), or consume leisure. Public policy may distort all of these decisions. A good policy thus has to create a balance between intertemporal and intratemporal distortions. Finally, we study the implications of lifespan uncertainty and missing annuity markets, asking how public policy can improve the allocation of resources by providing insurance against longevity risk. In this section we allow households to decide how many hours to work in each period. The remaining time is used for leisure consumption which now features in household utility. Leisure demand in each period of the life cycle strongly depends on the respective value of human capital hj, which measures the value of the time endowment in terms of labour market productivity. Hence agents may work the same number of hours, but they may be differently productive, so that they earn a different wage per time unit. Whenever the wage a household earns in the labour market is very small, the household might want to consume more leisure than the actual time endowment. In order to guarantee that the time endowment is met, we calculate a so-called shadow wage μj,s. The shadow wage is added to the regular wage of the household and calculated such that the household’s optimal decision consists in consuming the household’s total endowment of time as leisure.
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Ebrahimnejad, Roohollah, Mona Milani, Zahra Faraji, and Leila Nemati-Anaraki. "Creating Shared Value (CSV) and Creating Competitive Business." In Advances in Business Strategy and Competitive Advantage, 432–53. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7265-7.ch024.
Повний текст джерелаАнотація:
Shared value concept could reshape capitalism and its relationship to society. It's not just about corporate social responsibility or philanthropy. It's a new approach for business strategy regarding social issues. It could also drive the next wave of innovation and productivity growth in the global economy as it opens managers' eyes to immense human needs that must be met, large new markets to be served, and the internal costs of social deficits—as well as the competitive advantages available from addressing them. But our understanding of shared value is still in its genesis. Attaining it will require managers to develop new skills and knowledge and governments to learn how to regulate in ways that enable shared value rather than work against it. A big part of the problem lies with companies themselves, which remain trapped in an outdated, narrow approach to value creation. Focused on optimizing short-term financial performance, they overlook the greatest unmet needs in the market as well as broader influences on their long-term success. Why would companies ignore the wellbeing of their customers, the depletion of natural resources vital to their businesses, the viability of suppliers, and the economic distress of the communities in which they produce and sell? Companies could bring business and society back together if they redefined their purpose as creating “shared value”—generating economic value in a way that also produces value for society by addressing its challenges. A shared value approach reconnects company success with social progress. Firms can do this in three distinct ways: reconceiving products and markets, redefining productivity in the value chain, and building supportive industry clusters at the company's locations.
Тези доповідей конференцій з теми "Regular wave generation"
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Chai, Kenric, M. S. Liew, and H. E. Lee. "Numerical wave tank modelling of regular waves propagation using OpenFOAM." In 2017 3rd International Conference on Power Generation Systems and Renewable Energy Technologies (PGSRET). IEEE, 2017. http://dx.doi.org/10.1109/pgsret.2017.8251825.
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Fouques, Sébastien, Sébastien Laflèche, Andreas Akselsen, and Thomas Sauder. "An Experimental Investigation of Nonlinear Wave Generation by Flap Wavemakers." In ASME 2021 40th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/omae2021-63120.
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Abstract It is well known that flap wavemakers behave in a nonlinear way when either the flap angle or the flap velocity becomes large. Moreover, the hinge depth should be adapted to the period of the generated waves in order to minimize linear evanescent modes, which may contribute to the formation of nonlinear spurious waves. For example, imposing a sinusoidal motion with a relatively long period and a large amplitude to a short flap will result in a surface elevation composed of a regular wave with the same period as the flap motion, but also of a variety of harmonics with higher frequencies. Second-order harmonics can be predicted theoretically for regular and irregular waves, and they can be corrected by modifying the control signal of the wavemaker. However, there is no theory that can describe nor mitigate effects of orders higher than two. The design of the wavemaker is then essential to generate extreme sea states with good quality and predictability in a laboratory. In this paper, the nonlinearities of flap wavemakers are investigated experimentally for regular and irregular waves generated in SINTEF Ocean’s laboratories. Nonlinearities of order two and three are estimated from times series of the surface elevation measured at different locations by an array of wave probes. Particular focus is put on identifying the effects of the classical second-order correction on the second- and third-order harmonics.
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Hirai, Takayuki, Akira Sou, and Yasunori Nihei. "Wave Load Acting on Advanced Spar in Regular Waves." In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-77821.
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Offshore wind turbines have been investigated and developed as one of the renewable energies. In Japan, the research and development of floating type offshore wind turbines have been carried out because the water around the country is too deep to settle the bottom mounted type. In this paper, we investigate the effects of the diameter of the column floater of the advanced spar in regular wave by using open source computational fluid dynamics software OpenFOAM. We use olaFOAM which equipped with the functions to set the boundary conditions of wave generation at the inlet and wave absorption at the outlet. The forces acting on a spar obtained by the numerical simulation and Morison’s equation are compared to examine the validity of the numerical model. A good agreement between them confirms the validity of the numerical method. Then we simulate numerically the effects of the column diameter on the flow around the advanced spars and the wave load. The result clarifies that Morison’s equation overestimates the wave force, and the difference increases with the column diameter. For more detailed analysis we divide the advanced spar into three parts, the upper spar above the column, the column floater and the lower spar below the column. As a result, we find that the difference between the wave load acting on the column by Morison’s equation and that by numerical simulation is dominant due to the flow separation around the column. Finally we modify the load coefficients of Morison’s equation for the column so that the modified equation can accurately evaluate the wave load acting on the advanced spar.
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Yamanaka, Shingo, Takayuki Hirai, Yasunori Nihei, and Akira Sou. "Interaction Between Advanced Spar and Regular Waves." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61788.
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Advanced spar type of the floating wind turbine with a short spar and a cylindrical column floater has been developed and tested recently. However, numerical methods to accurately simulate the interaction between the advanced spar and waves have not been established yet. In this study we simulated the free surface flow around an advanced spar in regular waves using open source computational fluid dynamics (CFD) software OpenFOAM to examine its applicability. We used olaFOAM which equipped with the functions to set the boundary conditions of wave generation at the inlet and wave absorption at the exit. An experiment of the advanced spar model fixed in space in the regular waves with various wave periods was also conducted to obtain an experimental database on the horizontal and vertical forces acting on the structure and pressure distribution on the floater surface. The results of the forces obtained by the numerical simulation, experiment, Morison’s equation were compared to examine the validity of the numerical model. Numerical and experimental results of the horizontal and vertical forces as well as pressure distribution on the floater surface were in good agreement, which confirmed the validity of the present numerical method. Then, we evaluated numerically the effects of the edge of the column by simulating a sharp-edged and a chamfered column floater. The result clarified that a chamfered edge decreased the wake which reduced the forces acting on the floater structure.
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Lande, Øystein, and Jens Bloch Helmers. "CFDwavemaker: An Open-Source Library for Efficient Generation of Higher Order Wave Kinematics." In ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/omae2022-81272.
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Abstract Computational fluid dynamics (CFD) for propagation of waves have become an important tool for the calculation of wave loading on offshore structures for such problems as run-up, wave slamming and other load related problems where nonlinear breaking wave kinematics is of importance. There are multiple CFD codes, both commercial and open source which today supports features related to wave propagation. Examples are OpenFOAM, ComFLOW, Basilisk, StarCCM+ and more. All of these codes require the either initialization of the domain or propagation of waves from the boundaries, with a known theoretical solution or with the use of wave paddles. In terms of higher order theoretical wave descriptions, the most frequent implementations are often limited to uni-directional regular waves, which is well defined and efficient to calculate. However, ocean waves are neither regular nor long crested. CFDwavemaker is a cross-platform open-source library which provides higher order non-linear wave kinematics for irregular and short-crested waves, purpose built for initialization and generation of waves at the domain boundary of CFD domains. The library is written in C++ and may be compiled and linked into most CFD codes. The library has built-in second order irregular wave theory and supports the use of Higher-order Spectral methods (HoS) as input through the extension Spectral Wave Data (SWD). The code is designed to utilize multiprocessing and advanced interpolation schemes which are favorable for efficient generation of higher-order wave kinematics generation.
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Li, Qian, Venugopal Vengatesan, and Nigel Barltrop. "Combined Wave-Current-Turbulent Flow Environments Generation for Tidal Turbine Design." In ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-19109.
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Abstract In this paper, a methodology to generate combined wave, tidal current and turbulent flow environment for application to determining hydrodynamic loading on a horizontal axis Tidal Stream Turbine (TST) is proposed. A systematic investigation has been conducted within the framework of OpenFAST software suite. Necessary modifications in OpenFAST tool is made to simulate the hydrodynamics of the TST under combined wave-current-turbulence conditions. The modified software will be able to generate the inflow conditions for the TST accounting for the regular and irregular wave and current interactions, and, involve the impact of ambient turbulence on the loadings of TST. The modified algorithm is validated by comparing the numerical results with experimental test data and other numerical simulation results. Good agreements are achieved for both regular and irregular wave kinematics in time-domain and flow velocity/elevation spectra in the frequency domain. Also, each of the wave-current configuration has been tested with different turbulence intensities. The results suggests that the wave kinematics is greatly altered when waves propagating on currents and wave travelling on the following and opposing directions current shows remarkably different characteristics in relation to wave amplitude and frequency. It is also found that combined wave-current flow with different turbulence levels have strong correlations with the flow properties which is important for TST fatigue prediction. All the conclusions emphasis the fact that proper wave-current-turbulence interactions should be included in TST modelling.
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Jeongsoo, Kim, Park Min-Su, Jeong Youn-Ju, and Hwang Yoon-Koog. "Experimental and Numerical Analysis of Hybrid 3kW Ocean Wave-Power Generation System Subjected to Regular and Irregular Wave Forces." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61245.
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In particular of coastal area, needs of ocean energy development have emerged with global demands on non-pollution energy. Although there are several types of wave-power generation systems, such as an attenuator and an overtopping device, these have problems related to frequent damages or limited applicable area. This study is concerned with development of a new hybrid wave-power system, which is expected to provide higher power efficiency than the previous system, and experimental and numerical estimations on performance of the new system. The proposed wave power absorber is composed of a generator embedded in the floating shield cylinder, pendulum plate to accelerate rotation of generator, self-dynamic positioning devices, and a support column to fix the entire power generation system to the seabed. To determine major design parameters and to conduct a specific concept design of the proposed power generation system, hydrodynamic tests of the floating shield cylinder were carried out. The cylinder was scaled with a scale factor 0.12. Several test specimens were fabricated to examine effects of the following physical characteristics on the system performance: draft depth of the cylinder, diameter of the cylinder, longitudinal projective area of the cylinder, a number of blades attached on the cylinder, blade length. Each specimen was subjected to 8 regular and 4 irregular wave loads for 5 minutes; an extreme water wave condition was also included. In the hydrodynamic tests, rotation numbers of the cylinder per a minute were measured. Although consistent patterns of the angular velocity of the cylinder was not observed from the experimental results, the results showed that the ratio of draft depth to diameter mainly effects on the angular velocity of the cylinder, and that the cylinder quickly rotates at the crest of an incident wave while it inversely and slowly rotates at the through. Furthermore, to supplement the above tests and to analyze mechanical behaviors of the support system, numerical simulations of the system were also conducted. To calculate water pressure on the cylinder and the support column, the commercial computational program ANSYS AQWA was used. The distribution and the magnitude of the predicted water pressure were then mapped into the finite element model of the cylinder and the support structure to examine the structural responses and stability against overturning.
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Schmittner, Christian, Joris Brouwer, and Janou Hennig. "Application of Focusing Wave Groups in Model Testing Practice." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23949.
Повний текст джерелаАнотація:
For hydrodynamic model testing different types of model waves are applied, where the most common ones are regular (monochromatic) and irregular (multichromatic) waves. In addition to these wave types the application of focusing wave groups, which are also often denoted as wave packages or transient wave packets, can give insight into aspects that cannot be assessed by the conventional model waves. This paper describes the different applications of focusing wave groups for hydrodynamic model testing. The paper starts with the historical background, followed by a theoretical description and the generation procedure. The main part of the paper is dedicated to the practical application of focusing wave groups in the basin. Items that will be described are a) the derivation of transfer functions for floating structures and for anti-roll tanks b) the determination of hydraulic and electrical transfer function of wave makers c) the verification of position and calibration of wave probes in the basin d) the generation of extreme wave events e) the assessment of reflection coefficient of beaches f) the investigation of non-linear aspects of transfer functions. Finally, characteristics of the analysis of focusing waves are introduced and compared to conventional methods based on regular and irregular waves.
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Choi, Youngmyung, Benjamin Bouscasse, Sopheak Seng, Guillaume Ducrozet, Lionel Gentaz, and Pierre Ferrant. "Generation of Regular and Irregular Waves in Navier-Stokes CFD Solvers by Matching With the Nonlinear Potential Wave Solution at the Boundaries." In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-78077.
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The capability of wave generation and absorption in a viscous flow solver becomes important for achieving realistic simulations in naval and offshore fields. This study presents an efficient generation of nonlinear wave fields in the viscous flow solver by using a nonlinear potential solver called higher-order spectral method (HOS). The advantages of using a fully nonlinear potential solver for the generation of irregular waves are discussed. In particular, it is shown that the proposed method allows the CFD simulation to start at the time and over the space of interest, retrieved from the potential flow solution. The viscous flow solver is based on the open source library OpenFOAM. The potential solvers used to generate waves are the open source solvers HOS-Ocean and HOS-NWT (Numerical Wave Tank). Several simulation parameters in the CFD solver are investigated in the present study. A HOS wrapper program is newly developed to regenerate wave fields in the viscous flow solver. The wrapper program is validated with OpenFOAM for 2D and 3D regular and irregular waves using relaxation zones. Finally, the extreme waves corresponding to the 1000 year return period condition in the Gulf of Mexico are simulated with the viscous flow solver and the wave elevation is compared with the experiments.
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Ganesan T., Shivaji, Amresh Negi, and Debabrata Sen. "IMO Level 3: Parametric Roll Stability Failure Simulation Using 3D Numerical Wave Tank." In ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/omae2022-79654.
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Abstract In late 2020, International Maritime Organization (IMO) released interim guidelines on the second generation intact stability criteria. In this paper direct stability assessment in design situations using deterministic approach for parametric rolling failure mode is presented. A 3D nonlinear direct time domain method based on mixed-Eulerian-Lagrangian (MEL) scheme as opposed to impulse response function (IRF) method is used to simulate parametric rolling in both regular and irregular waves. Computed numerical results of roll amplitude in regular head waves is validated with other available literature results. This study further examines the influence of incident wave height and roll damping coefficient on computed heave, roll, and pitch motions in regular head wave conditions. Mean 3-hour maximum roll amplitude is obtained for design situations as recommended by the IMO guidelines.