152 research outputs found
“Living Under Different Skies”: Misrepresenting Egyptian Education during the British Occupation in the North American Press
During the British occupation from 1882 to 1922, Egypt saw the rise of colonial educational reforms, American missionary projects, and foreign-subsidized schools. Consequently, newspapers in North America reported extensively on these colonial educational excursions. In the view of correspondents, the so-called “enlightenment” of Egyptians was dependent on their adoption of Western moral ideals and instructional models. The main criticisms levelled at Egyptian education centred on what was viewed as the “incompetence” of native instructors and schools, namely Muslim ones, as well as the need for the modern education of young women. Moreover, Christian or Western schooling was posited as the way to “civilize” these indigenous populations.
Overall, these writings not only helped simultaneously construct both the “abroad” and the oppositional, superior identity of the West to readers, but also legitimated the British occupation as a whole. Therefore, journalism in North America was upholding and reinforcing a colonially-mediated representation of the realities in Egypt. In response to this misrepresentation, Egyptian writers and activists took to Western publications to dispel such denigrating narratives and appealing to readers to consider the failures of their British colonizers. This study of collected articles on Egyptian education in North American newspapers at the time reveals and deconstructs Western observers’ misrepresentations of schools and teaching and learning activities in Egypt
The production and evaluation of squeeze cast A1-alloy matrix-short ceramic fibre composites
Research work on metal matrix-fibre composites has concentrated in
the past on aligned fibre composites. The poor transverse strength
of these composites is seen as a major hindrance to their practical
use in the majority of engineering applications because stresses exist
in more than one direction. Materials with isotropic properties are
preferred and consequently reinforcement of composites in three dimensions
will be necessary.
With this objective, an investigation was conducted to assess the method
of fabrication and properties of A1-a110y reinforced with short fibres
(SiC and A1 203) randomly oriented in three dimensions. Two composite
systems were examined: Al-4.S Cu alloy reinforced with SiC fibre;
and Al-3.7S Mg alloy reinforced with A1 203 fibre.
The general approach was to establish a satisfactory manufacturing
method for the composites before evaluating their mechanical properties.
The vortex technique was used to introduce the fibres into the molten
alloy. Pre-treatment of the fibres, to induce wetting, and the use of
a specially designed device for fibre separation and introduction to
the molten A1-ai10ys was found to be necessary so that a uniform distribution
of fibres oriented in three dimensions could be achieved.
The composites were squeeze cast, under conditions which were experimentally
determined, to ensure the production of pore-free castings
with fine equiaxed structures. The improvement in tensile strength and
ductility of the cast metal, provided by squeeze casting, would be
beneficial to composite properties.
Composite castings, with up to 10% volume fibre, were produced with a
sound structure and with fibres that were uniformly distributed and
randomly oriented in three dimensions.
It was found that the reaction between the fibres and the respective
molten alloy must be closely controlled so that fibre reinforcement
can be realised. In this respect the optimum time of contact between
the fibres and the molten alloy was experimentally defined for both
composite systems.
The tensile properties (UTS, 0.1% proof stress, and ductility) of the
fibre-free alloys were substantially improved by squeeze casting. The
addition of fibre produced further substantial improvement in the tensile
properties of the squeeze cast composites, in particular elastic
modulus and 0.1% proof stress. Furthermore, composite properties were
isotropic. The improvement in the tensile properties of composite
castings (as a result of the addition of fibre) was maintained at elevated
temperatures. At 250oC, castings of both composite systems with
10% (volume) fibre had 0.1% proof stress and elastic modulus values
similar to those for the fibre-free castings at room temperature ..
The tensile properties of the composite castings were not affected by
thermal cycling (at experimental conditions). The fatigue life of the
squeeze cast composite was substantially improved over and above the
initial improvement in fatigue life of the fibre-free castings produced
by squeeze casting. Wear of cutting tools was adversely affected by the
presence of fibres
Two-Particle Self-Consistent method for the multi-orbital Hubbard model
One of the most challenging problems in solid state systems is the
microscopic analysis of electronic correlations. A paramount minimal model that
encodes correlation effects is the Hubbard Hamiltonian, which -- albeit its
simplicity -- is exactly solvable only in a few limiting cases and approximate
many-body methods are required for its solution. In this review we present an
overview on the non-perturbative Two-Particle Self-Consistent method (TPSC)
which was originally introduced to describe the electronic properties of the
single-band Hubbard model. We introduce here a detailed derivation of the
multi-orbital generalization of TPSC and discuss particular features of the
method on exemplary interacting models in comparison to dynamical mean-field
theory results.Comment: 22 pages, 10 figure
Limits and consistency of non-local and graph approximations to the Eikonal equation
In this paper, we study a non-local approximation of the time-dependent
(local) Eikonal equation with Dirichlet-type boundary conditions, where the
kernel in the non-local problem is properly scaled. Based on the theory of
viscosity solutions, we prove existence and uniqueness of the viscosity
solutions of both the local and non-local problems, as well as regularity
properties of these solutions in time and space. We then derive error bounds
between the solution to the non-local problem and that of the local one, both
in continuous-time and Backward Euler time discretization. We then turn to
studying continuum limits of non-local problems defined on random weighted
graphs with vertices. In particular, we establish that if the kernel scale
parameter decreases at an appropriate rate as grows, then almost surely,
the solution of the problem on graphs converges uniformly to the viscosity
solution of the local problem as the time step vanishes and the number vertices
grows large
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