Aerodynamics of vortex generators

An experimental and theoretical study was undertaken of the separation delay and dramatic boundary-layer thinning that can occur in vortex-generator installations. Wind tunnel measurements of the dynamic-pressure profile downstream of a vortex generator were found to compare under certain conditions with that downstream of a suction slit, while water-tunnel visualization studies of vortex-generator height and geometry suggested optimum configurations, and only a minor effect of base porosity. A series of progressively more complex inviscid flow models was developed to be applied to a 3-D integral boundary-layer code. This code predicted layer thinning downstream of the suction site of the vortex models, and other observed features. Thin-layer Navier-Stokes equations are now being used with the ultimate goal of clarifying the physical processes involved in vortex generator performance and developing calculational procedures capable of predicting it

Noise characterization for resonantly-enhanced polarimetric vacuum magnetic-birefringence experiments

In this work we present data characterizing the sensitivity of the Bir\'{e}fringence Magnetique du Vide (BMV) instrument. BMV is an experiment attempting to measure vacuum magnetic birefringence (VMB) via the measurement of an ellipticity induced in a linearly polarized laser field propagating through a birefringent region of vacuum in the presence of an external magnetic field. Correlated measurements of laser noise alongside the measurement in the main detection channel allow us to separate measured sensing noise from the inherent birefringence noise of the apparatus. To this end we model different sources of sensing noise for cavity-enhanced polarimetry experiments, such as BMV. Our goal is to determine the main sources of noise, clarifying the limiting factors of such an apparatus. We find our noise models are compatible with the measured sensitivity of BMV. In this context we compare the phase sensitivity of separate-arm interferometers to that of a polarimetry apparatus for the discussion of current and future VMB measurements

Reciprocal Teaching: One of the Methods for Poor Comprehenders

Reciprocal teaching is a method which emphasizes the students' cognitive and meta cognitive domains for it covers the structural process of the instruction. The whole elements within the procedure enable the students to choose the strategy, plan, monitor, and evaluate their own activities. Furthermore, the procedures integrated in this method are believed to enhance the students' thinking process. The method, introduced by Palinscar and Brown, belongs to cooperative learning in that the students' thinking process in learning is expressed through a natural dialogue. This method is designed to improve the students' competency in text reading while those students find it difficult to comprehend the content of the text. The method also encourages the students to apply such four strategies as predicting, summarizing, questioning, and clarifying

Strengthening group decision making within shared governance: a case study

Shared governance is an approach to empowering nurses and other health care workers to have authority for decisions concerning their practice. Commonly, visible definers of shared governance are groups of workers known as ‘councils’ whose membership works collectively to realise a shared goal. The literature is replete with rhetoric as to the benefits of shared governance yet the evidence base concerning shared governance and especially decision-making within shared governance is scant. This paper presents a case study of group decision-making within a UK shared governance council model. The evidence which informs the case study is drawn from a doctoral action-research study to strengthen decision-making within the model. Eight key factors affecting decision-making and four supportive conditions are presented and incorporated into a conceptual model. Within the case study, presence of these factors was found to be necessary but not sufficient to enhance decision-making. Factors included having a clear issue, clear aim, fitting issue, manageable issue, size, lead person allocated, level of authority, background information, key informant/s, a mechanism for evaluation, adequately skilled members, support/guidance and sufficient/appropriate membership. Aspects of group decision-making processes are highlighted and compared with established management, shared governance and group dynamics theory