Effect of Adaptive Tabs on Drag of a Square-Base Bluff Body

This thesis involves the experimental wind tunnel testing of a 0.127m by 0.127m square-base bluff body to test the effectiveness of trailing edge tabulations to reduce drag in the Cal Poly 0.912m by 1.219 m low-speed wind tunnel. To accomplish this, the boundary layer was first measured on the trailing edge of the model for the three speeds at 10, 20, and 30 m/s, with Re = 8.3e4, 1.6e5 and 2.5e5 respectively, without the tabs. Three different tests were performed to determine the effectiveness of the tabs. These tests included base pressure measurements, total drag force measurements and hotwire velocity fluctuation measurements. These tests were repeated with tabs on the model’s trailing edge at the three different tab heights and without tabs at all three test speeds. The base pressure measurements showed a decrease in average base pressure with the addition of tabs which signifies an increase in drag. The total drag measurements confirmed this by showing that the overall force increases with the addition of the tabs. The hotwire tests further confirm this by showing that the vortex is present for every configuration tested. This thesis showed that the addition of tabs was unsuccessful in reducing the effects of the vortex shedding for a square-base bluff body. The addition of low, medium, and high tabs to the square base of the bluff body all showed an increase in vortex strength and overall drag. Further study is required to determine if drag savings are feasible for tabs all around the square base of the bluff body and at different locations

Dilemmas in Teaching Happiness

There is a burgeoning amount of research into happiness and greatly increased popular attention, so it seems logical to add a course on happiness to the university curriculum. We encountered, in developing and running such a course, a number of dilemmas that the topic of happiness makes especially acute. Should the teacher remain separate from the class, as an authority, or participate in group activities? Is the primary goal of the class to learn content or to change the relationship of students to the world? What does a mark for learning content signify if developing happiness habits is a goal? Should one goal of the class be for the teacher to be happy and, if so, does this conflict with student learning? These dilemmas reflect larger questions about the purpose of university education. This paper reflects on those questions through our experience of formulating and delivering a new university class on happiness

Reviews

Mark Kerr, How to Promote your Web Site Effectively, London: Aslib/IMI, ISBN: 0–85142–424–4. Paperback, 87 pages, £13.99

Sulfur Emerges as a Nutritional Issue in Iowa Alfalfa Production

Sulfur is often classified as a “secondary” essential element, mainly due to a smaller plant requirement, but also because it is less frequently applied as a fertilizer compared to N, P, and K. This has certainly been the case in Iowa, where research had not documented S deficiency or fertilization need for optimal crop production. However, if deficient, S can have a dramatic effect on plant growth and crop productivity – more than the classification “secondary” would imply

Sulfur Fertilization Response in Iowa Corn Production

With the positive results from S fertilization in alfalfa (see related article, page 6), trials were started in 2006 corn fields where early plant growth was exhibiting S deficiency symptoms or where there was expectation of S deficiency. Calcium sulfate (CaSO4•H2O, gypsum) was surface broadcast applied after early corn growth at 40 lb S/A, with a control treatment for comparison. The 40 lb S/A rate was chosen as a non-limiting S rate to maximize any potential yield increase

³¹P Saturation Transfer and Phosphocreatine Imaging in the Monkey Brain

³¹P magnetic resonance imaging with chemical-shift discrimination by selective excitation has been employed to determine the phosphocreatine (PCr) distribution in the brains of three juvenile macaque monkeys. PCr images were also obtained while saturating the resonance of the {gamma}-phosphate of ATP, which allowed the investigation of the chemical exchange between PCr and the {gamma}-phosphate of ATP catalyzed by creatine kinase. Superposition of the PCr images over the proton image of the same monkey brain revealed topological variations in the distribution of PCr and creatine kinase activity. PCr images were also obtained with and without visual stimulation. In two out of four experiments, an apparently localized decrease in PCr concentration was noted in visual cortex upon visual stimulation. This result is interpreted in terms of a possible role for the local ADP concentration in stimulating the accompanying metabolic response

Reviews

Sally Brown, Steve Armstrong and Gail Thompson (eds.), Motivating Students, London: Kogan Page, 1998. ISBN: 0–7494–2494‐X. Paperback, 214 pages. £18.99

Sulfur fertilization response in Iowa corn and soybean production

Sulfur (S) is often classified as a “secondary” plant essential element, mainly due to a smaller plant requirement but also because it is less frequently applied as a fertilizer compared to other nutrients like the “macronutrients” nitrogen (N), phosphorus (P), and potassium (K). This has certainly been the case in Iowa where research for many years had not documented S deficiency or fertilization need for optimal corn or soybean production. However, if deficient, S can have a dramatic effect on plant growth and crop productivity – more than the classification “secondary” would imply. In Iowa, before 2005 more than forty years of field research with corn and soybean conducted at many locations across the state had measured a yield response to S fertilizer application only three times out of approximately 200 trials – an indication of adequate available S supply and limited deficiency. This began to change in the early 2000’s as producers in northeast Iowa noticed yellow plant foliage and reduced growth in areas of alfalfa fields. After investigating several potential reasons for the growth problems, such as plant diseases, research in multiple fields documented improved alfalfa plant coloration, growth, and forage yield with S fertilizer application (Lang et al., 2006). These responses, as well as questions about deficiency symptoms in corn, led to investigation of potential response to S application in corn and soybean