595 research outputs found
Monitored background radiometer
The infrared (IR) testing of the Olympus thermal model has provided a capability to perform cost effective thermal balance testing of satellites and satellite components. A high-accuracy monitored background radiometer was developed for the measurement of absorbed radiation heat flux encountered during IR thermal vacuum testing of spacecraft. The design, development, and calibration of this radiometer is described
Centralizers of maximal regular subgroups in simple Lie groups and relative congruence classes of representations
In the paper we present a new, uniform and comprehensive description of
centralizers of the maximal regular subgroups in compact simple Lie groups of
all types and ranks. The centralizer is either a direct product of finite
cyclic groups, a continuous group of rank 1, or a product, not necessarily
direct, of a continuous group of rank 1 with a finite cyclic group. Explicit
formulas for the action of such centralizers on irreducible representations of
the simple Lie algebras are given.Comment: 27 page
Manifestations cliniques du âburn outâ chez les mĂ©decins
Dans cet article, l'auteur délimite les caractéristiques du burn out. Pour ce faire, iI fait un court historique du concept pour ensuite le définir par ses phases, ses symptÎmes cliniques, son étiologie et son traitement. Tout au long du texte, l'auteur appuiera ses dires sur des exemples tirés de la profession médicale.In this article, the author outlines the characteristics of "burn out". A short historical concept is presented and defined through its phases, clinical symptoms, etiology and treatment. Throughout his article, the author supports his thesis with drawn examples from the medical profession
The origin of the E+ transition in GaAsN alloys
Optical properties of GaAsN system with nitrogen concentrations in the range
of 0.9-3.7% are studied by full-potential LAPW method in a supercell approach.
The E+ transition is identified by calculating the imaginary part of the
dielectric function. The evolution of the energy of this transition with
nitrogen concentration is studied and the origin of this transition is
identified by analyzing the contributions to the dielectric function from
different band combinations. The L_1c-derived states are shown to play an
important role in the formation of the E+ transition, which was also suggested
by recent experiments. At the same time the nitrogen-induced modification of
the first conduction band of the host compound are also found to contribute
significantly to the E+ transition. Further, the study of several model
supercells demonstrated the significant influence of the nitrogen potential on
the optical properties of the GaAsN system.Comment: 5 pages, 3 figure
The rings of n-dimensional polytopes
Points of an orbit of a finite Coxeter group G, generated by n reflections
starting from a single seed point, are considered as vertices of a polytope
(G-polytope) centered at the origin of a real n-dimensional Euclidean space. A
general efficient method is recalled for the geometric description of G-
polytopes, their faces of all dimensions and their adjacencies. Products and
symmetrized powers of G-polytopes are introduced and their decomposition into
the sums of G-polytopes is described. Several invariants of G-polytopes are
found, namely the analogs of Dynkin indices of degrees 2 and 4, anomaly numbers
and congruence classes of the polytopes. The definitions apply to
crystallographic and non-crystallographic Coxeter groups. Examples and
applications are shown.Comment: 24 page
Illustrer le territoire quĂ©bĂ©cois dans les manuels dâhistoire au secondaire : Ă©tude de cas sur le paysage en tant quâoutil de mĂ©diation culturelle et ses rapports avec lâespace, le pouvoir et lâidentitĂ©
Dans le prĂ©sent article, nous proposons une rĂ©flexion sur lâusage du paysage dans trois manuels dâhistoire quĂ©bĂ©cois. Nous lâabordons premiĂšrement en considĂ©rant le cadre de rĂ©fĂ©rence (ou le contexte de production) de ces documents visuels, de nature artistique, scientifique ou mĂ©diatique,relatifs Ă lâarchitecture. Nous analysons ces trois types de paysages pour discuter des rapports quâils entretiennent avec le rĂ©el, notamment concernant un certain effet dâauthenticitĂ© et dâobjectivitĂ©. Il sâagit alors de considĂ©rer le paysage en tant quâoutil de mĂ©diation culturelle. Nous poursuivons la rĂ©flexion sur lâusage du paysage par une analyse thĂ©matique de lieux associĂ©s Ă la ville de MontrĂ©al dans les manuels. Ensuite, nous prĂ©sentons une grille de lecture des documents iconographiques qui pourrait sâappliquer Ă tout paysage considĂ©rĂ© comme document iconographique pour susciter un questionnement productif sur le plan des informations que lâon peut en tirer.
In this paper, we propose a reflection on the use of the landscape in three Quebec history textbooks. We turn first considering the terms of reference (or the context of production) of these visual documents, produced from an artistic, scientific or mediatic point of view. We analyze these three types of landscapes to discuss their relationship with reality, especially regarding some effect of authenticity and objectivity. It is then to consider the landscape as a tool for cultural mediation. We continue the reflection on the use of the landscape by a thematic analysis of places associated with the city of Montreal in textbooks. Thirdly, we present a reading grid of graphic materials that could be applied to any landscape considered as graphic material, in order to question it in terms of information that can be learned
Biofuels Production from Biomass by Thermochemical Conversion Technologies
Agricultural biomass as an energy resource has several environmental and economical advantages and has potential to substantially contribute to present daysâ fuel demands. Currently, thermochemical processes for agricultural biomass to energy transformation seem promising and feasible. The relative advantage of thermochemical conversion over others is due to higher productivity and compatibility with existing infrastructure facilities. However, the majority of these processes are still under development phase and trying to secure a market share due to various challenges, right from suitable infrastructure, raw material, technical limitations, government policies, and social acceptance. The knowledge at hand suggests that biomass can become a sustainable and major contributor to the current energy demands, if research and development are encouraged in the field of thermochemical conversion for various agricultural biomass types. This paper intends to explore the physical and chemical characteristics of biofuel substitutes of fossil fuels, potential biomass sources, and process parameters for thermochemical conversion
Nonlinear magnetoinductive transmission lines
Power transmission in one-dimensional nonlinear magnetic metamaterials driven
at one end is investigated numerically and analytically in a wide frequency
range. The nonlinear magnetic metamaterials are composed of varactor-loaded
split-ring resonators which are coupled magnetically through their mutual
inductances, forming thus a magnetoiductive transmission line. In the linear
limit, significant power transmission along the array only appears for
frequencies inside the linear magnetoinductive wave band. We present
analytical, closed form solutions for the magnetoinductive waves transmitting
the power in this regime, and their discrete frequency dispersion. When
nonlinearity is important, more frequency bands with significant power
transmission along the array may appear. In the equivalent circuit picture, the
nonlinear magnetoiductive transmission line driven at one end by a relatively
weak electromotive force, can be modeled by coupled
resistive-inductive-capacitive (RLC) circuits with voltage-dependent
capacitance. Extended numerical simulations reveal that power transmission
along the array is also possible in other than the linear frequency bands,
which are located close to the nonlinear resonances of a single nonlinear RLC
circuit. Moreover, the effectiveness of power transmission for driving
frequencies in the nonlinear bands is comparable to that in the linear band.
Power transmission in the nonlinear bands occurs through the linear modes of
the system, and it is closely related to the instability of a mode that is
localized at the driven site.Comment: 11 pages, 11 figures, submitted to International Journal of
Bifurcation and Chao
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