Analytical Model of the Time Developing Turbulent Boundary Layer

We present an analytical model for the time-developing turbulent boundary layer (TD-TBL) over a flat plate. The model provides explicit formulae for the temporal behavior of the wall-shear stress and both the temporal and spatial distributions of the mean streamwise velocity, the turbulence kinetic energy and Reynolds shear stress. The resulting profiles are in good agreement with the DNS results of spatially-developing turbulent boundary layers at momentum thickness Reynolds number equal to 1430 and 2900. Our analytical model is, to the best of our knowledge, the first of its kind for TD-TBL.Comment: 5pages, 9 figs, JETP Letters, submitte

The construction and evaluation of an achievement test of musical knowledge for grades VII-XII.

Thesis (M.M.E.)--Boston Universit

'CHOOSER DEPENDANT' PREFERENCES, AND ATTITUDES de se

Sen’s 'chooser dependence' of preferences generates issues of indexicality which, we claim, can in fact be reduced to a specification of the content of preferences within a standard approach, by means of Lewis’ theory of attitudes de se. While context sensitivity of preferences can be dealt with by the addition to the outcomes of choice of their relevant mereological contexts, indexical sensitivity requires the content of preferences to include (the nature of) the decision maker him/herself. The result is a naturalistic internalization of preferences, which become object of preference, belief, and action. Keywords: Preferences, utility, choice, attitudes, mereology, properties.

Applications of surface analysis and surface theory in tribology

Tribology, the study of adhesion, friction and wear of materials is a complex field which requires a knowledge of solid state physics, surface physics, chemistry, material science and mechanical engineering. It has been dominated, however, by the more practical need to make equipment work. With the advent of surface analysis and advances in surface and solid state theory, a new dimension has been added to the analysis of interactions at tribological interfaces. In this paper the applications of tribological studies and their limitations are presented. Examples from research at the NASA Lewis Research Center are given. Emphasis is on fundamental studies involving the effects of monolayer coverage and thick films on friction and wear. A summary of the current status of theoretical calculations of defect energetics is presented. In addition, some new theoretical techniques which enable simplified quantitative calculations of adhesion, fracture and friction are discussed

Exoelectron emission from a clean, annealed magnesium single crystal during oxygen adsorption

Exoelectron emission was observed from a clean, annealed Mg (0001) surface during oxygen and chlorine adsorption at pressures of 6.5x10 0.00001- N/sq m and lower. the studies were performed in an ultrahigh vacuum system. The crystals were cleaned by argon ion bombardment and annealed at 300 C. Auger electron spectroscopy was used to verify surface cleanliness, and low energy electron diffraction was used to verify that the surface was annealed. The emission was found to be oxygen arrival rate dependent. Two peaks were observed in the electron emission with exposure. Evidence is presented that the formation of the second peak corresponds to oxidation of the Mg surface. No emission was observed from clean aluminum during adsorption. Results verify that electron emission occurs from a strain free surface simply upon adsorption of oxygen. A qualitative explanation for the mechanisms of emission in terms of chemical effects is presented

Tribology theory versus experiment

Tribology, the study of friction and wear of materials, has achieved a new interest because of the need for energy conservation. Fundamental understanding of this field is very complex and requires a knowledge of solid-state physics, material science, chemistry, and mechanical engineering. This paper is meant to be didactic in nature and outlines some of the considerations needed for a tribology research program. The approach is first to present a simple model, a field emission tip in contact with a flat surface, in order to elucidate important considerations, such as contact area, mechanical deformations, and interfacial bonding. Then examples from illustrative experiments are presented. Finally, the current status of physical theories concerning interfacial bonding are presented

Education, Aspirations and Life Satisfaction

The idea that expanding work and consumption opportunities always increases people’s wellbeing is well established in economics but finds no support in psychology. Instead, there is evidence in both economics and psychology that people’s life satisfaction depends on how experienced utility compares with expectations of life satisfaction or decision utility. In this paper I suggest that expanding work and consumption opportunities is a good thing for decision utility but may not be so for experienced utility. On this premise, I argue that people may overrate their socioeconomic prospects relative to real life chances and I discuss how systematic frustration over unfulfilled expectations can be connected to people’s educational achievement. I test the model’s predictions on Italian data and find preliminary support for the idea that education and access to stimulating environments may have a perverse impact on life satisfaction. I also find evidence that the latter effect is mediated by factors such as gender and age. Indeed, the model seeks to go beyond the Italian case and provide more general insights into how age/life satisfaction relationships can be modelled and explained.education, opportunities, aspirations, life satisfaction, regret