Gyrotorque transmission system for wind turbines

The GyroTorqueTM transmission system employs gyroscopic torque reaction to transmit power offering an alternative to the gearbox and electrical variable speed drive of a conventional wind turbine. The power transmission is fundamentally oscillatory and is rectified by mechanical elements. A precessing gyro maps speed to torque and, since the wind turbine rotor inertia strongly filters rotor speed variation, output power is insensitive to wind turbulence because it reflects wind turbine rotor speed variability rather than rotor torque variability. The GyroTorqueTM system has only bearing losses and potentially a high efficiency. Mechanical control of the input to the GyroTorqueTM system enables wide range variable speed operation of the wind turbine rotor using a conventional synchronous generator. At present, a 6 gyro system driven by an axial cam and connected to a conventional synchronous generator is the preferred system. Loads and power quality have been addressed with computer simulation models of the GyroTorqueTM system. Outline assessment of system mass and cost gives encouragement that it may be less than for conventional transmission systems

Innovative concepts for aerodynamic control of wind turbine rotors

New systems for the aerodynamic control of wind turbine rotors are being studied in various projects funded by the UK Department of Energy. Results from a current project, ongoing at the National Wind Turbine Test Centre (NWTC) in Scotland are presented. These systems show the promise of much cheaper and more affective active control of horizontal axis wind turbines than has been achieved with full span and partial span pitching systems

Experiencing discrimination increases risk taking.

Prior research has revealed racial disparities in health outcomes and health-compromising behaviors, such as smoking and drug abuse. It has been suggested that discrimination contributes to such disparities, but the mechanisms through which this might occur are not well understood. In the research reported here, we examined whether the experience of discrimination affects acute physiological stress responses and increases risk-taking behavior. Black and White participants each received rejecting feedback from partners who were either of their own race (in-group rejection) or of a different race (out-group rejection, which could be interpreted as discrimination). Physiological (cardiovascular and neuroendocrine) changes, cognition (memory and attentional bias), affect, and risk-taking behavior were assessed. Significant participant race × partner race interactions were observed. Cross-race rejection, compared with same-race rejection, was associated with lower levels of cortisol, increased cardiac output, decreased vascular resistance, greater anger, increased attentional bias, and more risk-taking behavior. These data suggest that perceived discrimination is associated with distinct profiles of physiological reactivity, affect, cognitive processing, and risk taking, implicating direct and indirect pathways to health disparities

Notes on eclampsia

The following is a record of the cases of Eclampsia which I have attended over a period of twenty years, together with a suggestion as to the mode of origin of the disease, some observations on treatment,and a commentary on my analysis of 137 cases recently reported in New Zealand. The series of Eclampsias that occurs in a private practice not largely of an obstetrical character is naturally a small one; and it may reasonably be objected that no general conclusions should be made from such limited experience. Nevertheless, the actual experience of a small number is extraordinarily instructive, and suggestive information can be gained by careful study of the details of a few cases perhaps more easily than from large statistics in which detail is obscured by the mass of material, and personal contact is lacking. My personal experience covers 15 cases in which there has been a culmination of the disease in convulsions, and a number of cases of pre- eclamptic toxaemia of varying degrees of severity. I find I have preserved meagre notes of 22 such, but that is only a fraction of the number actually seen. Perfection of recording in general practice is too difficult an ideal to attain. It is opportune here to remark that a definition of Eclampsia is not really easy. It is too closely associated in our minds with fibs, and we regard fits as being a necessary feature. I am convinced that this is irrational and wrong. Convulsions are merely the terminal phase of a toxaemia occurring in pregnant women, which presents any other symptoms quite as essential and characteristic. It would, I think, be just as reasonable to regard coma as a disease entity, apart from the diabetes, or whatever else is the cause; or to think of septic peritonitis as a disease, apart from the perforation,or appendicitis producing it. Further, the syndrome of Eclampsia is very varied. Almost each individual common symptom of it may be absent in a given case. The common symptoms are albuminuria, oedema, headache, sensory disturbances, especially of sight, raised blood pressure, and fits, occurring in pregnancy. But on reference to my own cases, and to other recorded cases, I find Eclampsia without albuminuria, Eclampsia without oedema, Eclampsia without headache, Eclampsia without sensory disturbance, and even Eclampsia without fits. There remain only two constant features - pregnancy, and a blood pressure which seems to have been found invariably raised whenever it has been taken

Caring for continence in stroke care settings: a qualitative study of patients’ and staff perspectives on the implementation of a new continence care intervention

Objectives: Investigate the perspectives of patients and nursing staff on the implementation of an augmented continence care intervention after stroke. Design: Qualitative data were elicited during semi-structured interviews with patients (n = 15) and staff (14 nurses; nine nursing assistants) and analysed using thematic analysis. Setting: Mixed acute and rehabilitation stroke ward. Participants: Stroke patients and nursing staff that experienced an enhanced continence care intervention. Results: Four themes emerged from patients’ interviews describing: (a) challenges communicating about continence (initiating conversations and information exchange); (b) mixed perceptions of continence care; (c) ambiguity of focus between mobility and continence issues; and (d) inconsistent involvement in continence care decision making. Patients’ perceptions reflected the severity of their urinary incontinence. Staff described changes in: (i) knowledge as a consequence of specialist training; (ii) continence interventions (including the development of nurse-led initiatives to reduce the incidence of unnecessary catheterisation among patients admitted to their ward); (iii) changes in attitude towards continence from containment approaches to continence rehabilitation; and (iv) the challenges of providing continence care within a stroke care context including limitations in access to continence care equipment or products, and institutional attitudes towards continence. Conclusion: Patients (particularly those with severe urinary incontinence) described challenges communicating about and involvement in continence care decisions. In contrast, nurses described improved continence knowledge, attitudes and confidence alongside a shift from containment to rehabilitative approaches. Contextual components including care from point of hospital admission, equipment accessibility and interdisciplinary approaches were perceived as important factors to enhancing continence care

Estimation of the power electronic converter lifetime in fully rated converter wind turbine for onshore and offshore wind farms

A comparison has been made of the converter lifetime for a 3MW fully rated converter horizontal axis wind turbine located onshore and offshore. Simulated torque and speed of the turbine shaft were used to calculate voltage and current time series, that was used to calculate the junction temperatures of the diode and IGBT in the generator-side converter by a thermal-electrical model. A rainflow counting algorithm was applied to the junction temperature in combination with an empirical model of the lifetime estimation, to calculate the lifetime of the power electronic modules in the turbine. The number of parallel modules for each location to achieve 20 years life time has also been found. Simulations show the lifetime consumption rate of the diode and IGBT is decreased exponentially by increasing number of parallel modules, lowering the average temperature. The offshore wind turbine has a higher lifetime consumption rate, requiring a slightly higher converter rating to achieve a 20-year lifetime, but this difference is small, and both turbines will use the same number of modules

Dependencia de la densidad en los ánades norteamericanos

The existence or otherwise of density dependence within a population can have important implications for the management of that population. Here, we use estimates of abundance obtained from annual aerial counts on the major breeding grounds of a variety of North American duck species and use a state space model to separate the observation and ecological system processes. This state space approach allows us to impose a density dependence structure upon the true underlying population rather than on the estimates and we emonstrate the improved robustness of this procedure for detecting density dependence in the population. We adopt a Bayesian approach to model fitting, using Markov chain Monte Carlo (MCMC) methods and use a reversible jump MCMC scheme to calculate posterior model probabilities which assign probabilities to the presence of density dependence within the population, for example. We show how these probabilities can be used either to discriminate between models or to provide model–averaged predictions which fully account for both parameter and model uncertainty.La existencia o ausencia de efectos dependientes de la densidad en una población puede acarrear importantes repercusiones para la gestión de la misma. En este artículo empleamos estimaciones de abundancia obtenidas a partir de recuentos aéreos anuales de las principales áreas de reproducción de diversas especies de ánades norteamericanos, utilizando un modelo de estados espaciales para separar los procesos de observación y los procesos del sistema ecológico. Este enfoque basado en estados espaciales nos permite imponer una estructura que depende de la densidad de la población subyacente real, más que de las estimaciones, además de demostrar la robustez mejorada de este procedimiento para detectar la dependencia de la densidad en la población. Para el ajuste de modelos adoptamos un planteamiento bayesiano, utilizando los métodos de Monte Carlo basados en cadenas de Markov (MCMC), así como un programa MCMC de salto reversible para calcular, por ejemplo, las probabilidades posteriores de los modelos que asignan probabilidades a la presencia de una dependencia de la densidad en la población. También demostramos cómo pueden emplearse estas probabilidades para discriminar entre modelos o para proporcionar predicciones promediadas entre modelos que tengan totalmente en cuenta tanto la incertidumbre referente a parámetros como a modelos

Density dependence in North American ducks

The existence or otherwise of density dependence within a population can have important implications for the management of that population. Here, we use estimates of abundance obtained from annual aerial counts on the major breeding grounds of a variety of North American duck species and use a state space model to separate the observation and ecological system processes. This state space approach allows us to impose a density dependence structure upon the true underlying population rather than on the estimates and we demonstrate the improved robustness of this procedure for detecting density dependence in the population. We adopt a Bayesian approach to model fitting, using Markov chain Monte Carlo (MCMC) methods and use a reversible jump MCMC scheme to calculate posterior model probabilities which assign probabilities to the presence of density dependence within the population, for example. We show how these probabilities can be used either to discriminate between models or to provide model-averaged predictions which fully account for both parameter and model uncertainty