Hydrodynamic forces on heave plates for offshore systems oscillating close to the seabed or the free surface

La energía eólica marina es uno de los recursos energéticos con mayor proyección pudiendo contribuir a reducir el consumo de combustibles fósiles y a cubrir la demanda de energía en todo el mundo. El concepto de aerogenerador marino está basado en estructuras fijas como jackets o en plataformas flotantes, ya sea una semisumergible o una TLP. Se espera que la energía eólica offshore juegue un papel importante en el perfil de producción energética de los próximos años; por tanto, las turbinas eólicas deben hacerse más fables y rentables para ser competitivas frente a otras fuentes de energía. Las estructuras flotantes pueden experimentar movimientos resonantes en estados de la mar con largos períodos de oleaje. Estos movimientos disminuyen su operatividad y pueden causar daños en los componentes eléctricos de las turbinas y en las palas, también en los risers y moorings. La respuesta de la componente vertical del movimiento puede reducirse mediante diferentes actuaciones: (1) aumentando la amortiguación del sistema, (2) manteniendo el período del movimiento vertical fuera del rango de la energía de la ola, y (3) reduciendo las fuerzas de excitación verticales. Un ejemplo típico para llevar a cabo esta reducción son las "Heave Plates". Las heave plates son placas que se utilizan en la industria offshore debido a sus características hidrodinámicas, ya que aumentan la masa añadida y la amortiguación del sistema. En un análisis hidrodinámico convencional, se considera una estructura sometida a un oleaje con determinadas características y se evalúan las cargas lineales usando la teoría potencial. El amortiguamiento viscoso, que juega un papel crucial en la respuesta en resonancia del sistema, es un dato de entrada para el análisis. La tesis se centra principalmente en la predicción del amortiguamiento viscoso y de la masa añadida de las heave plates usadas en las turbinas eólicas flotantes. En los cálculos, las fuerzas hidrodinámicas se han obtenido con el f n de estudiar cómo los coeficientes hidrodinámicos de masa añadida5 y amortiguamiento varían con el número de KC, que caracteriza la amplitud del movimiento respecto al diámetro del disco. Por otra parte, se ha investigado la influencia de la distancia media de la ‘heave plate’ a la superficie libre o al fondo del mar, sobre los coeficientes hidrodinámicos. En este proceso, un nuevo modelo que describe el trabajo realizado por la amortiguación en función de la enstrofía, es descrito en el presente documento. Este nuevo enfoque es capaz de proporcionar una correlación directa entre el desprendimiento local de vorticidad y la fuerza de amortiguación global. El análisis también incluye el estudio de los efectos de la geometría de la heave plate, y examina la sensibilidad de los coeficientes hidrodinámicos al incluir porosidad en ésta. Un diseño novedoso de una heave plate, basado en la teoría fractal, también fue analizado experimentalmente y comparado con datos experimentales obtenidos por otros autores. Para la resolución de las ecuaciones de Navier Stokes se ha usado un solver basado en el método de volúmenes finitos. El solver usa las librerías de OpenFOAM (Open source Field Operation And Manipulation), para resolver un problema multifásico e incompresible, usando la técnica VOF (volume of fluid) que permite capturar el movimiento de la superficie libre. Los resultados numéricos han sido comparados con resultados experimentales llevados a cabo en el Canal del Ensayos Hidrodinámicos (CEHINAV) de la Universidad Politécnica de Madrid y en el Canal de Experiencias Hidrodinámicas (CEHIPAR) en Madrid, al igual que con otros experimentos realizados en la Escuela de Ingeniería Mecánica de la Universidad de Western Australia. Los principales resultados se presentan a continuación: 1. Para pequeños valores de KC, los coeficientes hidrodinámicos de masa añadida y amortiguamiento incrementan su valor a medida que el disco se aproxima al fondo marino. Para los casos cuando el disco oscila cerca de la superficie libre, la dependencia de los coeficientes hidrodinámicos es más fuerte por la influencia del movimiento de la superficie libre. 2. Los casos analizados muestran la existencia de un valor crítico de KC, donde la tendencia de los coeficientes hidrodinámicos se ve alterada. Dicho valor crítico depende de la distancia al fondo marino o a la superficie libre. 3. El comportamiento físico del flujo, para valores de KC cercanos a su valor crítico ha sido estudiado mediante el análisis del campo de vorticidad. 4. Introducir porosidad al disco, reduce la masa añadida para los valores de KC estudiados, pero se ha encontrado que la porosidad incrementa el valor del coeficiente de amortiguamiento cuando se incrementa la amplitud del movimiento, logrando un máximo de damping para un disco con 10% de porosidad. 5. Los resultados numéricos y experimentales para los discos con faldón, muestran que usar este tipo de geometrías incrementa la masa añadida cuando se compara con el disco sólido, pero reduce considerablemente el coeficiente de amortiguamiento. 6. Un diseño novedoso de heave plate basado en la teoría fractal ha sido experimentalmente estudiado a diferentes calados y comparado con datos experimentales obtenidos por otro autores. Los resultados muestran un comportamiento incierto de los coeficientes y por tanto este diseño debería ser estudiado más a fondo. ABSTRACT Offshore wind energy is one of the promising resources which can reduce the fossil fuel energy consumption and cover worldwide energy demands. Offshore wind turbine concepts are based on either a fixed structure as a jacket or a floating offshore platform like a semisubmersible, spar or tension leg platform. Floating offshore wind turbines have the potential to be an important part of the energy production profile in the coming years. In order to accomplish this wind integration, these wind turbines need to be made more reliable and cost efficient to be competitive with other sources of energy. Floating offshore artifacts, such oil rings and wind turbines, may experience resonant heave motions in sea states with long peak periods. These heave resonances may increase the system downtime and cause damage on the system components and as well as on risers and mooring systems. The heave resonant response may be reduced by different means: (1) increasing the damping of the system, (2) keeping the natural heave period outside the range of the wave energy, and (3) reducing the heave excitation forces. A typical example to accomplish this reduction are “Heave Plates”. Heave plates are used in the offshore industry due to their hydrodynamic characteristics, i.e., increased added mass and damping. Conventional offshore hydrodynamic analysis considers a structure in waves, and evaluates the linear and nonlinear loads using potential theory. Viscous damping, which is expected to play a crucial role in the resonant response, is an empirical input to the analysis, and is not explicitly calculated. The present research has been mainly focused on the prediction of viscous damping and added mass of floating offshore wind turbine heave plates. In the calculations, the hydrodynamic forces have been measured in order to compute how the hydrodynamic coefficients of added mass1 and damping vary with the KC number, which characterises the amplitude of heave motion relative to the diameter of the disc. In addition, the influence on the hydrodynamic coefficients when the heave plate is oscillating close to the free surface or the seabed has been investigated. In this process, a new model describing the work done by damping in terms of the flow enstrophy, is described herein. This new approach is able to provide a direct correlation between the local vortex shedding processes and the global damping force. The analysis also includes the study of different edges geometry, and examines the sensitivity of the damping and added mass coefficients to the porosity of the plate. A novel porous heave plate based on fractal theory has also been proposed, tested experimentally and compared with experimental data obtained by other authors for plates with similar porosity. A numerical solver of Navier Stokes equations, based on the finite volume technique has been applied. It uses the open-source libraries of OpenFOAM (Open source Field Operation And Manipulation), to solve 2 incompressible, isothermal immiscible fluids using a VOF (volume of fluid) phase-fraction based interface capturing approach, with optional mesh motion and mesh topology changes including adaptive re-meshing. Numerical results have been compared with experiments conducted at Technical University of Madrid (CEHINAV) and CEHIPAR model basins in Madrid and with others performed at School of Mechanical Engineering in The University of Western Australia. A brief summary of main results are presented below: 1. At low KC numbers, a systematic increase in added mass and damping, corresponding to an increase in the seabed proximity, is observed. Specifically, for the cases when the heave plate is oscillating closer to the free surface, the dependence of the hydrodynamic coefficients is strongly influenced by the free surface. 2. As seen in experiments, a critical KC, where the linear trend of the hydrodynamic coefficients with KC is disrupted and that depends on the seabed or free surface distance, has been found. 3. The physical behavior of the flow around the critical KC has been explained through an analysis of the flow vorticity field. 4. The porosity of the heave plates reduces the added mass for the studied porosity at all KC numbers, but the porous heave plates are found to increase the damping coefficient with increasing amplitude of oscillation, achieving a maximum damping coefficient for the heave plate with 10% porosity in the entire KC range. 5. Another concept taken into account in this work has been the heave plates with flaps. Numerical and experimental results show that using discs with flaps will increase added mass when compared to the plain plate but may also significantly reduce damping. 6. A novel heave plate design based on fractal theory has tested experimentally for different submergences and compared with experimental data obtained by other authors for porous plates. Results show an unclear behavior in the coefficients and should be studied further. Future work is necessary in order to address a series of open questions focusing on 3D effects, optimization of the heave plates shapes, etc.

O LÚDICO VIA FÁBULAS EM ATENDIMENTO PSICOTERAPÊUTICO: UM ESTUDO DE CASO CLÍNICO DE MOBBING

Esta pesquisa verifica a validade da utilização de fábulas em processo psicoterapêutico de paciente de Mobbing acometida de depressão e síndrome de pânico. Desenvolve-se por meio de estudo de caso avaliativo-interventivo evolutivo prolongado, com um total de 116 sessões semanais. Inicialmente realiza o diagnóstico clínico elaborado a partir do desenho da figura humana, extraído do teste projetivo House Tree and Person, de entrevista inicial semi-dirigida, e de coleta de relatos verbais e observações feitas durante os primeiros atendimentos. As sessões são realizadas com utilização ocasional de fábulas, associada ou não a técnicas de relaxamento de Schultz e Jacobson, com interpretação de sonhos e recomendação de filmes. O objetivo é verificar se as fábulas contribuem de forma positiva para o paciente compreender com mais facilidade as interpretações do psicoterapeuta, se diminui sua resistência ao falar dos seus conteúdos e se amplia à consciência simbólica. O primeiro momento interventivo tem a duração de aproximadamente 16 meses, o segundo, de 04 meses, quando é solicitado o segundo desenho e o terceiro processa-se em 09 meses, quando é solicitado o último desenho. No primeiro momento é proporcionado à paciente um ambiente facilitador com sustentação emocional (Holding), buscando resgatar sua ilusão, numa visão winnicottiana. Revela-se uma situação de Mobbing acompanhada de depressão manifesta e síndrome do pânico; com alto nível de exigência pessoal e profissional; grande passividade nos relacionamentos e na dinâmica do casal. Ao final desse momento, já consegue começar a desviar sua auto-agressividade para o meio externo de maneira mais positiva e socialmente aceita. No segundo momento predomina o encontro e aceitação de seu verdadeiro jeito de ser; enxerga o quanto estava se deixando prejudicar; mostra-se mais confiante, comunica-se e enfrenta melhor suas dificuldades afetivas. No terceiro momento demonstra estar segura e feliz. Cuida de sua aparência e sente prazer em ser notada socialmente. Demonstra ter aprendido a se defender em situações de confronto, com maior autonomia e verbaliza estar muito feliz com as mudanças, sorri com freqüência. A análise evolutiva dos desenhos confirmam esta boa evolução. A utilização de fábulas foi muito bem aceita pela paciente, que conseguiu por meio da leitura simbólica contida nas mesmas, aproximar-se de sua problemática e aprender a lidar com ela de forma mais saudável. Os resultados também indicam que a utilização de relaxamento associado à leitura das fábulas contribuiu para sua assimilação mais abrangente e profunda. O estudo ilustra a evolução do caso por meio de 24 vinhetas, devidamente analisadas em relação aos momentos descritos.(AU)

O LÚDICO VIA FÁBULAS EM ATENDIMENTO PSICOTERAPÊUTICO: UM ESTUDO DE CASO CLÍNICO DE MOBBING

Esta pesquisa verifica a validade da utilização de fábulas em processo psicoterapêutico de paciente de Mobbing acometida de depressão e síndrome de pânico. Desenvolve-se por meio de estudo de caso avaliativo-interventivo evolutivo prolongado, com um total de 116 sessões semanais. Inicialmente realiza o diagnóstico clínico elaborado a partir do desenho da figura humana, extraído do teste projetivo House Tree and Person, de entrevista inicial semi-dirigida, e de coleta de relatos verbais e observações feitas durante os primeiros atendimentos. As sessões são realizadas com utilização ocasional de fábulas, associada ou não a técnicas de relaxamento de Schultz e Jacobson, com interpretação de sonhos e recomendação de filmes. O objetivo é verificar se as fábulas contribuem de forma positiva para o paciente compreender com mais facilidade as interpretações do psicoterapeuta, se diminui sua resistência ao falar dos seus conteúdos e se amplia à consciência simbólica. O primeiro momento interventivo tem a duração de aproximadamente 16 meses, o segundo, de 04 meses, quando é solicitado o segundo desenho e o terceiro processa-se em 09 meses, quando é solicitado o último desenho. No primeiro momento é proporcionado à paciente um ambiente facilitador com sustentação emocional (Holding), buscando resgatar sua ilusão, numa visão winnicottiana. Revela-se uma situação de Mobbing acompanhada de depressão manifesta e síndrome do pânico; com alto nível de exigência pessoal e profissional; grande passividade nos relacionamentos e na dinâmica do casal. Ao final desse momento, já consegue começar a desviar sua auto-agressividade para o meio externo de maneira mais positiva e socialmente aceita. No segundo momento predomina o encontro e aceitação de seu verdadeiro jeito de ser; enxerga o quanto estava se deixando prejudicar; mostra-se mais confiante, comunica-se e enfrenta melhor suas dificuldades afetivas. No terceiro momento demonstra estar segura e feliz. Cuida de sua aparência e sente prazer em ser notada socialmente. Demonstra ter aprendido a se defender em situações de confronto, com maior autonomia e verbaliza estar muito feliz com as mudanças, sorri com freqüência. A análise evolutiva dos desenhos confirmam esta boa evolução. A utilização de fábulas foi muito bem aceita pela paciente, que conseguiu por meio da leitura simbólica contida nas mesmas, aproximar-se de sua problemática e aprender a lidar com ela de forma mais saudável. Os resultados também indicam que a utilização de relaxamento associado à leitura das fábulas contribuiu para sua assimilação mais abrangente e profunda. O estudo ilustra a evolução do caso por meio de 24 vinhetas, devidamente analisadas em relação aos momentos descritos.(AU)

Republican Scientific-Medical Library, The Republic of Armenia: progress and programs*

In 1990, the Republican Scientific-Medical Library (RSML) of the Ministry of Health of Armenia in collaboration with the Fund for Armenian Relief created a vision of a national library network supported by information technology. This vision incorporated four goals: (1) to develop a national resource collection of biomedical literature accessible to all health professionals, (2) to develop a national network for access to bibliographic information, (3) to develop a systematic mechanism for sharing resources, and (4) to develop a national network of health sciences libraries. During the last decade, the RSML has achieved significant progress toward all four goals and has realized its vision of becoming a fully functional national library. The RSML now provides access to the literature of the health sciences including access to the Armenian medical literature, provides education and training to health professionals and health sciences librarians, and manages a national network of libraries of the major health care institutions in Armenia. The RSML is now able to provide rapid access to the biomedical literature and train health professionals and health sciences librarians in Armenia in information system use. This paper describes the evolution of the RSML and how it was accomplished.

To Mary Ann [passages copied from several poems, written by an unknown student on November 21, 1790]

The creator of this document is unknown, though he was presumably a student at Harvard College, as the name of the college appears on the document twice. Both sides of the document are filled with passages of poetry, including one from Tobias George Smollett's "The Adventures of Roderick Random" and another from John Tapner's "A New Collection of Fables in Verse." The creator seems to have intended the document for someone named Mary Ann.

Amthāl Luqmān al-Ḥakīm wa-baʻḍ aqwāl al-ʻArab =: Locmani Sapientis Fabulae et selecta quaedam Arabum adagia

cum interpretatione latina & notis Thomae Erpenii.

Abkhazia, South Ossetia, Nagorno-Karabakh: unfrozen conflicts between Russia and the West. OSW Special Report, 9 July 2008

The Southern Caucasus is the site of three armed conflicts with separatist backgrounds, which have remained unsolved for years: the conflicts in Georgia's Abkhazia and South Ossetia, and Azerbaijan's conflict over Nagorno-Karabakh (including the areas around Nagorno-Karabakh which were seized by Armenian separatists in the course of the war). Neither Georgia nor Azerbaijan have had any control over the disputed areas since the early 1990s. Both states are simultaneously in conflict with the separatists' informal patrons, respectively Russia and Armenia. After over a decade of relative peace during which the conflicts remained frozen, tension has recently risen considerably: in the case of Abkhazia and South Ossetia, large-scale fighting may break out in the coming months, whereas in the case of Nagorno-Karabakh and the Azeri-Armenian conflict, such a threat may materialise within the next five years. The current formula for politically resolving the conflicts is ineffective and close to exhaustion, and the prospect of any alternative peace plans being developed is rather distant. The conflicts in the Southern Caucasus are of increasing concern to the West, mainly because of the Western actors' constantly growing political and economic involvement in Georgia and Azerbaijan (including support for reforms and development of the gas and oil transmission infrastructures), as well as its less intensive commitments in Armenia. An outbreak of open fighting over the separatist regions would destabilise the Southern Caucasus, largely undoing the results of the actions which the EU, NATO and the USA have taken in the region in recent years. Moreover, the situation in the Southern Caucasus, especially the separatisms themselves, have in fact become an element in the wider geopolitical game between the West and Russia. For Russia, the stakes are maintaining its influence in the region, and for the West, demonstrating its ability to effectively promote democracy and economic modernisation in the countries bordering it.

Reintegration or Reconquest? Georgia's policy towards Abkhazia and South Ossetia in the context of the internal and international situation. OSW Point of View, May 2008

The conflicts in Abkhazia and South Ossetia have been Georgia's main security problem since the beginning of the 1990s, and, along with the Armenian-Azeri conflict over Nagorno-Karabakh, have made up the main security problems in the South Caucasus.

The Rocky Road to an EU-Armenia Agreement: From U-turn to detour. CEPS Commentary, 3 February 2015

The EU was taken by surprise when the President of Armenia, Serzh Sargsyan, stood by his Russian counterpart and announced Armenia’s plans to join the Russian-led Customs Union in September 2013. After all, before this announcement Armenia and the EU had successfully concluded negotiations on their Association Agreement. Armenia is still suffering the consequences of the Kremlin’s coercion to reject this Association Agreement. Indeed, as Armenians around the world commemorate the centenary of the Armenian Genocide by Ottoman Turkey, the Republic of Armenia is facing mounting challenges. The country remains subject to an economic blockade by Turkey and is in conflict with Azerbaijan. Ever since President’s Sargsyan’s astonishing volte-face, the EU and Armenia are still in the process of trying to rework the failed agreement. The author of this commentary argues that because the future of any new agreement is uncertain, negotiations should be accompanied by a pragmatic EU-Armenia roadmap. This roadmap, alongside the start of the visa liberalisation process and Armenia’s signing up to the European Common Aviation Agreement and Horizon 2020, could become a deliverable at the Riga Summit on 26-27 April 2015.

From apathy to nationalist mobilisation: politics makes a comeback in Armenia. OSW COMMENTARY NUMBER 215 | 08.06.2016

In the military dimension, the Four-Day War in Nagorno-Karabakh (2–5 April 2016) changed little in the conflict zone. It has, however, had a significant impact on the situation in Armenia. The country was shocked out of the political malaise that had been the dominant mood in the last few years, and the Karabakh question, which used to animate political life in the late 1980s and early 1990s, once again became a driving force behind developments. In the internal dimension, the renewed fighting galvanised the political scene, triggered a rise in nationalist sentiments, mobilised the public and consolidated it around the Karabakh question, overshadowing the frustrations caused by the country’s difficult economic situation. In the external dimension, the war, which was viewed as Moscow-endorsed Azerbaijani aggression, undermined people’s trust in Russia and the Armenian-Russian alliance. It also made it clear for Armenians how uncertain the Russian security guarantees were and exacerbated their feelings of vulnerability and isolation on the international stage.

Fábulas.

Mode of access: Internet.

Fabulae aesōpicae collectae /

Preface in Latin. Text in Greek.

Eine Skizze der literarisch-typographischen Thätigkeit der Mechitharisten-Congregation in Wien aus Anlass des 50 jährigin Regierungs-Jubiläums Kaiser Franz Joseph I.

Illustrated.

Labyrinte de Versailles : suivant la copie à Paris, de l'Imprimerie royale, MDCXCIII.

Full page engravings after S. Le Clerc, of the fountains in the Labyrinth (which represented Aesop's fables) with prose epitomes of the fables and descriptive text by Ch. Perrault, and metrical versions of the fables by I. de Benserade. On plate 12 the attribution "L. Scherm fe." can be discerned.