Formal frames and deformations of affine connections

We will introduce formal frames of manifolds, which are a generalization of ordinary frames. Their fundamental properties are discussed. In particular, canonical forms are introduced, and torsions are defined in terms of them as a generalization of the structural equations. It will be shown that the vanishing of torsions are equivalent to the realizability of given formal frames as ordinary frames. We will also discuss deformations of linear connections on tangent bundles. An application to deformations of foliations are then given.Comment: A remark and a reference adde

Notes on projective structures with torsion

We show that projective structures with torsion are related to connections in a parallel way to the torsion-free ones. This is done in terms of Cartan connections by following Kobayashi and Nagano. For this purpose, we make use of a bundle of formal frames, which is a generalization of a bundle of frames. We will also describe projective structures in terms of Thomas--Whitehead connections by following Roberts. In particular, we formulate normal projective connections and show the fundamental theorem for Thomas--Whitehead connections regardless the triviality of the torsion. We will study some examples of projective structures of which the torsion is non-trivial while the curvature is trivial. In this article, projective structures are considered to be the same if they have the same geodesics and the same torsions.Comment: Corrected minor errors and typo

The road to academic title - the challenges and criteria for success

„Der Weg zum akademischen Titel: die Herausforderungen und Erfolgskriterien“. Eine qualitative Forschung über schwarzafrikanische männliche Studenten in Österreich. Die Zahl schwarzafrikanische Studenten beträgt etwa 0.18% der Gesamtzahl von tertiären Studenten in Österreich (Studienjahr 2008/9). Diese Forschung richtete sich auf diese Gruppe und untersuchte die Situation von 12 schwarzafrikanischen männlichen Studenten in Österreich und den Kriterien, die ihnen halfen, ihre Studien erfolgreich zu beenden. Die Forschung ist qualitativ. 12 schwarzafrikanische männliche Studenten wurden interviewt, und es wurde eine phänomenologische-analytische Methode verwendet, um ihre Antworten zu präsentieren. Die Befragten erwähnten insgesamt 30 Kriterien, die ihnen halfen, in ihren Studien erfolgreich zu sein. 10 aus 12 Befragten erwähnte (jeder) 2/3 der Faktoren. Das heißt: jeder der 10 BAMSA besaß ungefähr 70 % der Faktoren. Die Antworten weisen darauf hin, dass es keine signifikanten Unterschiede zwischen den negativen Erfahrungen der erfolgreichen schwarzafrikanischen Studenten in Österreich und den negativen Erfahrungen der Studienabbrecher geben könnte. Diese Hypothese soll durch eine mehr repräsentative/quantitative Forschung bestätigt werden.“The Road to Academic Title: the challenges and criteria for success“. A qualitative Research about Black African Male Students in Austria.Black African students are just about 0.18% of the total number of tertiary students in Austria (academic year 2008/9). This research examined the situation of 12 Black African male students in Austria and the criteria that helped them to be successful in their studies. The research is qualitative. 12 Black African Male Students (BAMSA) were interviewed and phenomenological analytic method was used to present their responses. The respondents mentioned a total of 30 criteria that helped them to be successful in their studies. Ten out of 12 respondents (each) mentioned 2/3 of the factors. In other words, each of the 10 BAMSA possessed about 70% of the factors. The responses suggest that there may not be significant differences between the negative experiences of the successful Black African students in Austria and the negative experiences of the dropouts. This claim is to be substantiated through a more representative research

Effect of Pre-Ageing Thermal Conditions on the Corrosion Properties of Antimony-Modified Al-Si-Mg Alloy

The purpose of this investigation was to evaluate the effect of pre-ageing thermal conditions on the corrosion properties of antimony-modified Al-Si-Mg alloy.The alloy was subjected to a Single Thermal Ageing Treatment; STAT (T6 temper-solution heat treatment and ageing) and Double thermal ageing treatment; DTAT (T7 temper- solution heat treatment and ageing for stabilization). These consist of solution heat treatment (SHT) at 540oC for 1hr, water quenched followed by an artificial ageing; DTAT and STAT. For the single thermal ageing treatment (STAT), quenched samples were aged at temperatures of 1800C for 2hrs, before cooling in air. In the double thermal ageing treatment (DTAT), quenched samples were pre-aged at a temperature of 90oC, 105oC and 120oC for 1- 5 hrs. This was followed by ageing at 180oC for 2hrs before cooling in air. The corrosion characteristic of the as-cast, Single Thermal Ageing Treatment (STAT) and Double Thermal Ageing Treatment (DTAT) were evaluated using weight loss and linear polarization techniques in a static 3.5%NaCl solution. From the results, the corrosion rate decreases with increasing pre-ageing time and temperatures. Equally, from the linear polarization data/curves, the corrosion rate of the treated alloy decreases at all ageing temperatures along with the ageing time. The Optical Microscope (OM) results of as-corroded samples revealed that the alloy suffers pitting/uniform corrosion. The corrosion behaviour of the DTAT samples in simulated seawater showed an excellent improvement in corrosion resistance than the as-cast and conventional STAT alloy.http://dx.doi.org/10.4314/njt.v34i4.

Chemical, mineralogical and petrological characterization of Gyaza iron ore deposit, Katsina State, Nigeria

No Abstract