Overhead transmission lines are prone to undergo large amplitude, low frequency vibrations when exposed to freezing rain and steady side winds. These vibrations are referred to as galloping. They involve a dominant vertical motion in addition to twisting and horizontal swaying. Field reports indicate that the majority of galloping cases are associated with lightly-iced lines with thin ice accretions. Previous studies have failed to explain this trend satisfactorily. The present thesis involves a series of wind tunnel experiments to understand the rotational effects in lightly-iced transmission line galloping. The work to restore and upgrade the wind tunnel used for the experiments are also reported. Aerodynamic loads are measured first on a stationary model of a short, representative section of a lightly-iced conductor. Subsequently, automated controls force the model to undergo rotational oscillations, and the aerodynamic loads measured from these dynamic tests are compared to the stationary results. The airflow in both sets of experiments is visualised by using a laser-based system. The stationary test shows that the well-established den Hartog criterion for predicting vertical galloping does not explain why lightly-iced lines gallop. The dynamic experiments however confirm the presence of rotation-induced lift, unaccounted for by quasi-steady theory and the den Hartog criterion. This additional lift force increases the coupling between the rotational and vertical directions and may promote coupled aerodynamic instability. Visualisations indicate that the surface irregularities of the ice and the rotational motion are jointly responsible for the rotation-induced lift forces observed in the aerodynamic measurements.

<p>This dissertation explores the stability of beams, plates and membranes due to subsonic aerodynamic flows or solar radiation forces. Beams, plates and membranes are simple structures that may act as building blocks for more complex systems. In this dissertation we explore the stability of these simple structures so that one can predict instabilities in more complex structures. The theoretical models include both linear and nonlinear energy based models for the structural dynamics of the featureless rectangular structures. The structural models are coupled to a vortex lattice model for subsonic fluid flows or an optical reflection model for solar radiation forces. Combinations of these theoretical models are used to analyze the dynamics and stability of aeroelastic and solarelastic systems. The dissertation contains aeroelastic analysis of a cantilevered beam and a plate / membrane system with multiple boundary conditions. The dissertation includes analysis of the transition from flag-like to wing-like flutter for a cantilevered beam and experiments to quantify the post flutter fluid and structure response of the flapping flag. For the plate / membrane analysis, we show that the boundary conditions in the flow direction determine the type of instability for the system while the complete set of boundary conditions is required to accurately predict the flutter velocity and frequency. The dissertation also contains analysis of solarelastic stability of membranes for solar sail applications. For a fully restrained membrane we show that a flutter instability is possible, however the post flutter response amplitude is small. The dissertation also includes analysis of a membrane hanging in gravity. This systems is an analog to a spinning solar sail and is used to validate the structural dynamics of thin membranes on earth. A linear beam structural model is able to accurately capture the natural frequencies and mode shapes. Finally, the dissertation explores the stability of a spinning membrane. The analysis shows that a nonlinear model is needed to produce a conservative estimate of the stability boundary.</p> / Dissertation

Thesis (M.App.Sc.) - Carleton University, 2006. / Includes bibliographical references (p.87-93). Also available in electronic format on the Internet.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 152-163). Also available via the Internet.

Thesis (Ph.D.)--University of Wyoming, 2008. / Title from PDF title page (viewed on August 5, 2009). Includes bibliographical references (p. 100-102).

The current research analyzed the flutter response of the Stonecutters Cable-Stayed Bridge in Hong Kong, which has a twin deck configuration, under the effect of wind. The aerodynamic instability response of the bridge steel deck of the main span is mainly the focus of the current project. Initially, a complete finite element bridge model was created in ABAQUS finite element software, representing all the structural elements of the Stonecutters Cable-Stayed Bridge in a lumped mass bridge model. The natural frequencies and the vibration modes were validated against the data available in the literature at first. Secondly, the effect of the mean wind loading for wind speeds between 35 m/s and 211 m/s were determined. The vertical and horizontal displacements and the torsional angle at mid-span are indicated to determine the bridge performance under mean wind load. Moreover the flutter instability was modeled based on Scanlan’s theory and the response of the bridge model at several different locations along the main and the side span and the top of the tower, were determined for wind speeds of 35 m/s and higher, where this critical aerodynamic instability is expected to occur. In addition, the responses of the bridge under natural wind data were also determined by applying a wind speed recorded data to the bridge model. Finally, the critical flutter wind speed and the flutter frequency were determined by Fast Fourier Transform in MATLAB program. The flutter onset wind speed was also determined.

The object of this work was to design and build equipment to measure the aerodynamic forces which will cause self-induced oscillations of a body having an unsymmetrical cross-section, such as a D-section. This self-induced oscillation has been called "stall flutter" or in electrical transmission lines, "galloping-transmission lines." It is hoped that this equipment will be used to gain basic Information about these aerodynamic forces.

A variety of cardiomyopathies are due to familial disease. Most are primarily associated with cardiac involvement and can lead to hypertrophic, dilated, or restrictive cardiomyopathy. Myotonic dystrophy (MD) is a multisystem disease with autosomal dominant inheritance and variable penetrance. Cardiac diseases are important causes of morbidity and mortality in MD patients. Patients with primary MD should be carefully investigated with an electrocardiogram, stress test, and an echocardiogram to identify preclinical cardiac involvement and to prevent life-threatening complications. Any new onset of atrial flutter or atrial fibrillation in a young patient without any underlying cardiac abnormality should be investigated for underlying myopathy. The authors report on a male adolescent with MD who presented with atrial flutter. The patient had been diagnosed with MD at birth. He had an impaired ejection fraction of 38% to 45%. The patient described sharp chest pain in the retrosternal area, with no radiation, that was induced by exercise.

No description available.

Många människor har en mobilapp-idé som de vill förverkliga men hindras av att det är oklart vad det sammelsurium av tillgängliga verktyg och möjliga tekniska lösningar för apputveckling består av. Det här arbetets huvudsakliga syfte är att undersöka vad det nämnda sammelsuriet består av. Arbetet tar avstamp i en app-idé, som går under namnet Paschas, som ska göra det möjligt att spela in och lyssna på inspelade berättelser kopplade till en geografisk plats. Alternativen i områden som är relevanta för Paschas undersöks och utifrån det väljs väg för utvecklingen av Paschas. Inte bara en, så som målet var formulerat, utan två prototyper i olika format togs fram. Arbetet har varit agilt och följt de kontinuerligt utvecklade kraven. / Many people have an app idea that they want to realize but are hindered by the conglomeration of available tools and possible technical solutions for app development. The main purpose of this work is to investigate what this conglomeration consists of. The work undertaken in this paper has its starting point in an app idea called Paschas, which aims to enable the recording of stories and the listening to recorded stories linked to a geographical location. The available options in relevant areas for Paschas are examined and a development path is chosen based on that. Not just one, as the goal was formulated, but two prototypes in different formats were developed. The work has been agile and followed continuously developed requirements.