1,055 research outputs found
A comparative laboratory and full-scale study of the near wake structure of a wind turbine
No full textThe operation of a wind turbine produces a downstream region of reduced wind speed, the so-called wake. The wake constitutes an important factor in determining the siting of turbines in wind farms. The mean wake characteristics, and their relation to the incident wind field and the local topography, are of primary importance for the estimation of available wind energy. The turbulent structure of the wake affects the loading and fatigue of downstream turbine rotors, and dictates the minimum spacing of the machines within a wind fam. In order, then, to achieve satisfactory performance from wind farms, especially in areas of complex terrain, a detailed knowledge of the above wake parameters is required.
The present paper describes a recent investigation into the properties of the wake of a three-bladed wind turbine. Measurements were made on both a full-scale machine, and on a replica model in the laboratory, at approximately 1/100 scale. The full-scale experiments were carried out on the Greek island of Samos, by workers from the University of Athens, and were based on comprehensive anemometry measurements. The small-scale experiments were conducted by a research group at the University of Edinburgh, Scotland, using the relatively new technique of particle image velocimetry (PIV).
A major objective of the work was to assess the validity of small-scale PIV measurements as a tool for investigating full-scale wind turbine phenomena. If successful, there would be significant attractions in using the PIV method, due to its ability to map the velocity in the entire rotor wake at a given instant PIV vector maps may be processed to yield both bulk wake measurements, such as velocity deficits, or data relating to the detailed structure of the wake, e.g. vorticity measurements. In the present campaign, velocity ratios measured 1.1 diameters (D) downstream of the rotor, ie. in the near wake, were compared, using data from full-scale and model scale
Apophatic Elements in the Theory and Practice of Psychoanalysis: Pseudo-Dionysius and C.G. Jung
No full textThis thesis identifies apophatic elements in the theory and practice of psychoanalysis through an examination of Pseudo-Dionysius and C.G. Jung. Pseudo-Dionysius brought together Greek and Biblical currents of negative theology and the via negativa. The apophatic concepts and metaphors which appear in the work of Pseudo-Dionysius are identified. The psychology of Jung can be read as a continuation and extension of the apophatic tradition. The presence of neoplatonic themes in Jung’s work is discussed, as well as his references to Pseudo-Dionysius. There is a thorough examination of Jung’s discussion of opposites, including his reception of Nicholas of Cusa’s concept of the coincidence of opposites. The role of the transcendent function in Jung’s psychology is reviewed. The work of contemporary scholars of religion, philosophers and Jungian theorists are compared to Jung’s using the lens of apophasis. There is an exploration of ways in which motifs in Pseudo-Dionysius’ Ecclesiatical Hierarchy resonate with contemporary psychoanalytic psychotherapy. This study demonstrates that apophatic motifs saturate Jung’s work. It provides a platform for research into apophasis in the wider field of psychoanalysis
Studying geometric structures in meso-scale flows
No full textGeometric shapes of coherent structures such as ramp or cliff like signals, step changes and waves, are commonly observed in meteorological temporal series and dominate the turbulent energy and mass exchange between the atmospheric surface layer and the layers above, and also relate with low-dimensional chaotic systems. In this work a simple linear technique to extract geometrical shapes has been applied at a dataset which was obtained at a location experiencing a number of different mesoscale modes. It was found that the temperature field appears much better organized than the wind field, and that cliff-ramp structures are dominant in the temperature time series. The occurrence of structural shapes was related with the dominant flow patterns and the status of the flow field. Temperature positive cliff-ramps and ramp-cliffs appear mainly during night time and under weak flow field, while temperature step and sine structures do not show a clear preference for the period of day, flow or temperature pattern. Uniformly stable, weak flow conditions dominate across all the wind speed structures. A detailed analysis of the flow field during two case studies revealed that structural shapes might be part of larger flow structures, such as a sea-breeze front or down-slope winds. During stagnant conditions structural shapes that were associated with deceleration of the flow were observed, whilst during ventilation conditions shapes related with the acceleration of the flow. © 2014 Halios, Helmis and Asimakopoulos
C.G. Jung et les théologiens
No full textHélène Kiener. C.G. Jung and the theologians. (C.G. Jung et les théologiens.)
This article is by one of the students of the psychologist C.G. Jung. She practised as a Jungian psychoanalyst in Strasbourg from 1946 to 1970. She deals here with the theological dimension, mostly implicit, of Jung's thouth, which is generally overlooked by theology. The author shows how the major theologians, who are the exception to the general rule, make room for Jungian anthropology, and she calls for a more open attitude in theology, because of the light thrown by Jung's thought on many theological statements.L'article qu'on lira est d'une élève du psychologue des profondeurs C. G. Jung. Elle a pratiqué elle-même l'analyse jungienne à Strasbourg de 1946 à 1970. La question traitée porte sur la dimension théologique généralement implicite de la pensée de Jung, assez négligée d'une manière générale par la théologie. L'auteur expose la manière dont les principaux théologiens, qui font exception , font droit à l'anthropologie jungienne, et en appelle à une ouverture plus grande de la théologie en raison de la lumière que la pensée de Jung jette sur bien des affirmations théologiques.Kiener Hélène. C.G. Jung et les théologiens. In: Revue d'histoire et de philosophie religieuses, 60e année n°3, Juillet-septembre 1980. pp. 293-311
Fast-response humidity measurements with the psychrometric method
No full textA simple method for correcting the time series of a wet temperature sensor characterized by slow response is presented in this paper. A first-order linear approximation of the heat transfer equation is used for correcting the wet temperature measurements. The sensor cutoff frequency is found by an easy experimental method using the phase spectrum between the wet temperature sensor and a much faster platinum thermometer under low wind speeds (up to 3 m s-1) and relatively dry atmosphere (relative humidity 20-40%). If such a correction is applied, the wet sensor output along with the computed vapor pressure time series using the psychrometric equation are considerably recovered. -Author
An experimental case study of the mean and turbulent characteristics of the vertical structure of the atmospheric boundary layer over the sea
No full textThe main characteristics of the mean and turbulent vertical structure of the Marine Atmospheric Boundary Layer (MABL) up to the height of 500 m are examined for an experimental case, using both remote and in situ sensing instrumentation. The observations indicate the existence of a very stable surface layer up to the height of 150-200 m followed by slightly stable to neutral conditions at higher levels, while a Low-Level Jet (LLJ) is developed, on the top of the intense surface based inversion. High values of the variance of the vertical wind component are observed at levels above the LLJ core, presumably associated with the shear forcing close to the LLJ. The plausible mechanism for the development of the LLJ is the inertial oscillation due to the frictional decoupling over the sea, which is associated with the strong stability of the MABL lower layer. © Gebrüder Borntraeger, Berlin, Stuttgart 2007
Letter from C.G. Ames to Thomas Lamb Eliot
No full texthttps://rdc.reed.edu/v1/resources/859b5c69-cfa2-40cf-b99a-a75fadd02e8f/thumb/128.jpgIt is possible that the author is Reverend Charles Gordon Ames, who was also a Unitarian minister and was in Germantown, Pennsylvania during this time
An Investigation of Transitional Phenomena from Laminar to Turbulent Natural Convection using Compressible Direct Numerical Simulation
No full textThe transitional phenomena from laminar to turbulent natural convection and the development process inside the channel are investigated using compressible direct numerical simulation (DNS). Numerical method of Roe scheme with preconditioning and dual time stepping are used for addressing natural convection flows with large temperature differences, which are low speed but the densities are variable. The results are qualitatively well consistent with the experimental data [1] and the transition point can be accurately captured. In addition, the development process respected to time can be clearly identified for four stages, which are laminar, unstable process, reliminarization and turbulence. After reaching the quasi-steady state, it can be observed that the laminar, transition and turbulence coexist in the same flow filed. Most important of all, the transitional phenomena are naturally induced by the effects of interactions between the buoyancy and shear stress without adding any fluctuations at inlet. It means that the numerical scheme and physical model adopted in this study has the potential to be a universal case for estimating the accuracy of turbulence model because the characteristics of parameters-free and independence from inlet condition
Poiesis and Obstruction in Art Practice
No full textThis PhD thesis examines the concept of poiesis, that is ‘calling into existence that which was not there before’, in the context of obstruction in studio practice. It poses the question ‘Is there a methodology that engages with obstruction which in turn calls new work’? In this thesis, the concept of poiesis emerging from the late Dr. Murray Cox’s ‘Aeolian Mode’, is analyzed alongside a concept of praxis, (a philosophical companion to poiesis), familiar to artistic practice. This thesis describes the orientation of the original idea, The Aeolian Mode, clinically developed by Dr. Murray Cox in Broadmoor Psychiatric Hospital. This PhD seeks to identify if there are similar ‘tenets of approach’ held within the methodology of ‘The Aeolian Mode’, that would be useful or are identifiable in artistic studio practice. This thesis draws on the work of the philosopher, Professor Richard Kearney, specifically Kearney’s ideas on the necessity of ‘the other’ for ‘radical possibility’ to occur. It maps a context of both Freudian and Jungian interpretations of art practice, identifying how these ideas have shaped the way art is seen today. Furthermore, it challenges the Freudian idea of ‘pathography’ and favours a Jungian approach of ‘individuation’ in the understanding of creative processes. It develops a ‘methodology of the conversation’, interviewing students, established artists, tutors about their approaches to obstruction/poiesis in art practice. Additionally, it examines my own obstruction to painting and identifies the methodology that released me from this obstruction. Conducting these interviews on art practice has enabled me to confirm my initial concerns about Freudian ‘pathography’ whilst validating the possibility of the Jungian concept of ‘individuation’ being of use to art practice. Finally, this PhD discusses the implications for further study and research, which have emerged during the ‘methodology of the conversation’ and the task of dissolving my obstruction to painting
On the temporal distribution of bursts and events in the stable marine atmospheric surface layer
No full textA methodology for tracing the bursting phenomenon occurring in the turbulent boundary-layer is applied to stable marine atmospheric boundary-layer (MABL) data, collected within the framework of the Coupled Boundary Layer Air-Sea Transfer, Low wind component experiment at Nantucket Island, 2003, Massachusetts, USA. For the definition of the events contributing to the bursting phenomenon, the quadrant analysis of the momentum flux with varying threshold value is utilized. The present work aims at the better understanding of the time scales of the microstructures in the MABL, by providing the number of the events and the groups and their mean duration and the time difference of all quadrants of the quadrant analysis, for different thresholds and under different meteorological conditions. The interrelation of the different time scales as well as the correlation between the quadrants are investigated and discussed. Also, it is demonstrated that the procedure of grouping events leads to bursts with a mean duration that is independent of the threshold value, for the most important quadrants of the momentum transfer (2 and 4). It is found that the combination of near-neutral conditions with low wind speed permits the development of larger duration events within the stable MABL. Finally, it is shown that the groups of events maintain adequate time and flux coherence only for quadrants 2 and 4. © Springer Science+Business Media B.V. 2008
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