1,354,433 research outputs found
Letter from Walter T. Diack to Laurence L Doggett (July 25, 1916)
No full textA letter from Walter T. Diack to Laurence L Doggett dated July 25, 1916. In the letter Diack informs Doggett about a letter that shows what life in the army is doing to Mr. Summers. It is not known where this quotation is as it is no longer attached to this letter. Mr. Summers may be Springfield College alumnus, James S. Summers who graduated in 1911. Also included in the letter, handwritten, is a mention of an Officer Conference. What this conference might have been is also not known
Letter from Walter T. Diack to Laurence L Doggett (July 25, 1916)
No full textA letter from Walter T. Diack to Laurence L Doggett dated July 25, 1916. In the letter Diack informs Doggett about a letter that shows what life in the army is doing to Mr. Summers. It is not known where this quotation is as it is no longer attached to this letter. Mr. Summers may be Springfield College alumnus, James S. Summers who graduated in 1911. Also included in the letter, handwritten, is a mention of an Officer Conference. What this conference might have been is also not known
Optimisation et nanostructuration de l'alliage d'Heusler thermoélectrique Fe2VAl
No full textThermoelectric materials allow the direct conversion of heat flow into electrical current and vice versa. They allow the development of all-solid state thermoelectric refrigeration or generation applications, compact and reliable. However, increasing the efficiency of thermoelectric modules requires the optimization of three interdependent parameters: optimizing the electronic properties of the material in order to obtain a high Seebeck coefficient and a low electrical resistivity, while minimizing the thermal conductivity. Bismuth telluride (Bi2Te3) is currently the reference material for thermoelectric applications at 300 K. However, the cost, scarcity and toxicity of telluride hinders its use in a mass market. The Fe2VAl alloy could become a substitute for Bi2Te3 for thermoelectric applications at 300 K. Indeed, its elements are abundant and inexpensive and the combination of its Seebeck coefficient (n- or p-type) and its electrical conductivity is better than Bi2Te3. However, its thermal conductivity is unfavorable for thermoelectric applications. Indeed, it is ten times higher than Bi2Te3.To solve this problem, a multi-scale approach is implemented during this thesis. This approach allows the scattering of a large part of the heat transporting phonon spectrum. To intensify the scattering of phonons at an atomic scale, solid solutions are synthesized. Self-substitution as well as substitutions with atoms of higher masses are explored (Ta, Sn), leading to a thermal conductivity of 10 W/(m K) in Fe2V0.96Ta0.07Al0.97 at 300 K. In addition to efficient phonon scattering, the optimization of electronic transport properties is also sought: a thermoelectric power factor of 6.7 mW / (m K2) is thus achieved in the above mentioned composition. At the nanoscale, nanoprecipitates constitute scattering centers for medium energy phonons. For this scale, the Al-Fe-V phase diagram has been explored around the Fe2VAl composition, looking for two-phase domains. Nanoprecipitates a second phase very rich in iron were thus obtained in a matrix of composition Fe2+xAl1-xV1-x. But the Seebeck coefficient of this nanocomposite is too low to combine the effect obtained on the thermal conductivity at this scale with those of the other scales. Finally, at the mesoscopic scale, it is the multiplication of the grain boundaries that efficiently scatters the low energy phonons. To do this, the grain size is reduced by powder metallurgy techniques. At this scale, the addition of nanoinclusions in the fine-grained matrix has also been explored. By combining all these effects, the thermal conductivity is strongly reduced and the thermoelectric performances of Fe2VAl are improved: a thermoelectric figure of merit of 0.3 is obtained at 300 K. All these results open interesting perspectives for the improvement of the thermoelectric properties of Fe2VAl.Les matériaux thermoélectriques permettent de convertir directement un flux de chaleur en courant électrique et vice-versa. Ils permettent le développement d’applications de réfrigération ou de génération thermoélectriques tout-solide, compactes et fiables. L’augmentation du rendement des modules thermoélectriques passe cependant par l'optimisation trois paramètres interdépendants : optimiser les propriétés électroniques du matériau afin d'obtenir un coefficient Seebeck élevé et une résistivité électrique faible, tout en minimisant la conductivité thermique. Le tellurure de bismuth (Bi2Te3) est actuellement le matériau de référence pour des applications thermoélectriques à 300 K. Cependant, le coût, la rareté et la toxicité du tellure empêchent son utilisation dans un marché de masse. L'alliage de composition Fe2VAl pourrait devenir un substitut à Bi2Te3 pour les applications thermoélectriques à 300 K. En effet, ses éléments sont abondants et peu coûteux et la combinaison de son coefficient Seebeck (type n ou p) et de sa conductivité électrique est meilleure que celle de Bi2Te3. Cependant, sa conductivité thermique est défavorable aux applications thermoélectriques. En effet, elle est dix fois plus grande que celle de Bi2Te3.Pour résoudre ce problème, une approche multi-échelles est mise en oeuvre au cours de cette thèse. Cette approche permet la diffusion d'une large part du spectre des phonons qui transportent la chaleur. Pour intensifier la diffusion des phonons à une échelle atomique, des solutions solides sont synthétisées. L'auto-substitution ainsi que des substitutions par des atomes de plus grandes masses sont explorées (Ta, Sn), conduisant à une conductivité thermique de 10 W/(m K) dans Fe2V0,96Ta0,07Al0,97 à 300 K. En plus de la diffusion efficace des phonons, l'optimisation des propriétés de transport électronique est également recherchée : un facteur de puissance thermoélectrique de 6,7 mW / (m K2) est ainsi atteint dans la composition précédemment mentionnée. A l'échelle nanométrique, des nanoprécipités constituent des centres de diffusion des phonons de moyenne énergie. Pour cette échelle, le diagramme de phases Al-Fe-V a été exploré autour de la composition Fe2VAl, à la recherche de domaines diphasés. Des nanoprécipités une seconde phase très riche en fer ont ainsi été obtenus dans une matrice de composition Fe2+xAl1-xV1-x. Mais le coefficient Seebeck de ce nanocomposite est trop faible pour combiner l’effet obtenu sur la conductivité thermique à cette échelle avec ceux des autres échelles. Enfin, à l’échelle mésoscopique, c’est la multiplication des joints de grains qui diffuse efficacement les phonons de basse énergie. Pour ce faire, la taille des grains est réduite par des techniques de métallurgie des poudres. A cette échelle, l'ajout de nanoinclusions dans la matrice à grains fins a été également exploré. En combinant tous ces effets, la conductivité thermique est fortement réduite et les performances thermoélectriques de Fe2VAl sont améliorées : un facteur de mérite thermoélectrique de 0,3 est obtenu à 300 K. L’ensemble de ces résultats ouvre des perspectives intéressantes pour l’amélioration des propriétés thermoélectriques de Fe2VAl
Optimization and nanostructuring of the thermoelectric Fe2VAl Heusler alloy
No full textLes matériaux thermoélectriques permettent de convertir directement un flux de chaleur en courant électrique et vice-versa. Ils permettent le développement d’applications de réfrigération ou de génération thermoélectriques tout-solide, compactes et fiables. L’augmentation du rendement des modules thermoélectriques passe cependant par l'optimisation trois paramètres interdépendants : optimiser les propriétés électroniques du matériau afin d'obtenir un coefficient Seebeck élevé et une résistivité électrique faible, tout en minimisant la conductivité thermique. Le tellurure de bismuth (Bi2Te3) est actuellement le matériau de référence pour des applications thermoélectriques à 300 K. Cependant, le coût, la rareté et la toxicité du tellure empêchent son utilisation dans un marché de masse. L'alliage de composition Fe2VAl pourrait devenir un substitut à Bi2Te3 pour les applications thermoélectriques à 300 K. En effet, ses éléments sont abondants et peu coûteux et la combinaison de son coefficient Seebeck (type n ou p) et de sa conductivité électrique est meilleure que celle de Bi2Te3. Cependant, sa conductivité thermique est défavorable aux applications thermoélectriques. En effet, elle est dix fois plus grande que celle de Bi2Te3.Pour résoudre ce problème, une approche multi-échelles est mise en oeuvre au cours de cette thèse. Cette approche permet la diffusion d'une large part du spectre des phonons qui transportent la chaleur. Pour intensifier la diffusion des phonons à une échelle atomique, des solutions solides sont synthétisées. L'auto-substitution ainsi que des substitutions par des atomes de plus grandes masses sont explorées (Ta, Sn), conduisant à une conductivité thermique de 10 W/(m K) dans Fe2V0,96Ta0,07Al0,97 à 300 K. En plus de la diffusion efficace des phonons, l'optimisation des propriétés de transport électronique est également recherchée : un facteur de puissance thermoélectrique de 6,7 mW / (m K2) est ainsi atteint dans la composition précédemment mentionnée. A l'échelle nanométrique, des nanoprécipités constituent des centres de diffusion des phonons de moyenne énergie. Pour cette échelle, le diagramme de phases Al-Fe-V a été exploré autour de la composition Fe2VAl, à la recherche de domaines diphasés. Des nanoprécipités une seconde phase très riche en fer ont ainsi été obtenus dans une matrice de composition Fe2+xAl1-xV1-x. Mais le coefficient Seebeck de ce nanocomposite est trop faible pour combiner l’effet obtenu sur la conductivité thermique à cette échelle avec ceux des autres échelles. Enfin, à l’échelle mésoscopique, c’est la multiplication des joints de grains qui diffuse efficacement les phonons de basse énergie. Pour ce faire, la taille des grains est réduite par des techniques de métallurgie des poudres. A cette échelle, l'ajout de nanoinclusions dans la matrice à grains fins a été également exploré. En combinant tous ces effets, la conductivité thermique est fortement réduite et les performances thermoélectriques de Fe2VAl sont améliorées : un facteur de mérite thermoélectrique de 0,3 est obtenu à 300 K. L’ensemble de ces résultats ouvre des perspectives intéressantes pour l’amélioration des propriétés thermoélectriques de Fe2VAl.Thermoelectric materials allow the direct conversion of heat flow into electrical current and vice versa. They allow the development of all-solid state thermoelectric refrigeration or generation applications, compact and reliable. However, increasing the efficiency of thermoelectric modules requires the optimization of three interdependent parameters: optimizing the electronic properties of the material in order to obtain a high Seebeck coefficient and a low electrical resistivity, while minimizing the thermal conductivity. Bismuth telluride (Bi2Te3) is currently the reference material for thermoelectric applications at 300 K. However, the cost, scarcity and toxicity of telluride hinders its use in a mass market. The Fe2VAl alloy could become a substitute for Bi2Te3 for thermoelectric applications at 300 K. Indeed, its elements are abundant and inexpensive and the combination of its Seebeck coefficient (n- or p-type) and its electrical conductivity is better than Bi2Te3. However, its thermal conductivity is unfavorable for thermoelectric applications. Indeed, it is ten times higher than Bi2Te3.To solve this problem, a multi-scale approach is implemented during this thesis. This approach allows the scattering of a large part of the heat transporting phonon spectrum. To intensify the scattering of phonons at an atomic scale, solid solutions are synthesized. Self-substitution as well as substitutions with atoms of higher masses are explored (Ta, Sn), leading to a thermal conductivity of 10 W/(m K) in Fe2V0.96Ta0.07Al0.97 at 300 K. In addition to efficient phonon scattering, the optimization of electronic transport properties is also sought: a thermoelectric power factor of 6.7 mW / (m K2) is thus achieved in the above mentioned composition. At the nanoscale, nanoprecipitates constitute scattering centers for medium energy phonons. For this scale, the Al-Fe-V phase diagram has been explored around the Fe2VAl composition, looking for two-phase domains. Nanoprecipitates a second phase very rich in iron were thus obtained in a matrix of composition Fe2+xAl1-xV1-x. But the Seebeck coefficient of this nanocomposite is too low to combine the effect obtained on the thermal conductivity at this scale with those of the other scales. Finally, at the mesoscopic scale, it is the multiplication of the grain boundaries that efficiently scatters the low energy phonons. To do this, the grain size is reduced by powder metallurgy techniques. At this scale, the addition of nanoinclusions in the fine-grained matrix has also been explored. By combining all these effects, the thermal conductivity is strongly reduced and the thermoelectric performances of Fe2VAl are improved: a thermoelectric figure of merit of 0.3 is obtained at 300 K. All these results open interesting perspectives for the improvement of the thermoelectric properties of Fe2VAl
Ballasted Railways in Senegal - Characterization of Bandia Limestone and Diack Basalt for Use as Ballast Materials
No full textInternational audienceThis paper first presents a more or less detailed inventory of the situation on ballasted railways in Senegal. This field research work highlights the particular heterogeneity that characterizes the arming of ballasted tracks, but also and above all the influence of environmental factors that pollute and degrade the tracks. The significant efforts made to moderate the railways are presented with the introduction of the Regional Express Train between Dakar and Blaise Diagne International Airport. An experimental work of characterization of aggregates is presented in a second step. The grain size studied is 25/50 mm as for any material studied for use as railway ballast. The materials studied come from Senegalese quarries and the objective is to see if they can be used as ballast materials in railways. With a hardness of 0.85, initial results show that Limestone from the Bandia quarries (Sindia, Thiès Region) does not have the characteristics required to be used as ballast. The hardness of Basalt from the Diack quarries (Ngoundiane, Thiès Region) is 17.11. The Diack Basalt gives also good physical and mechanical characteristics (cleanliness, absorption, density, Deval and Los Angeles). For Senegalese public works, Diack Basalt is a good material for railway ballast
Among the Deep Sea Fishers, volume 56, issue 2 (July 1958)
No full textThere must be something about it -- The return to fishing -- The Fishermen [verse] / Traditional -- Student from St. Andrews / Andrew McAdam -- Log of the Star / Hughlett Acreman, Lesley M. Diack, S.R.N. -- Our staff -- Alumni news -- The Grenfell Associations -- The International Grenfell AssociationAmong the Deep Sea Fishers: the Official Organ of the International Grenfell Association. This journal was published quarterly from 1903 to 1981 with the twofold purpose of providing "a record of Mission activities [and] also a strong and convincing appeal to every supporter and friend of Dr. Grenfell's work." The articles describe mission life, services and experiences. The Mission began under the auspices of the Royal National Mission to Deep Sea Fishermen but later a separate mission, the International Grenfell Association, was formed by Dr. Wilfred Grenfell
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mary Diack at an automatic book sewing machine for Braille, ca.1933
No full textPhotograph of Mary Diack at an automatic book sewing machine for Braille, ca.1933. Standing left of a large piece of machinery bearing the name "Oversewing Co.", a woman in an apron slides a book through a metal section. The machinery is an elaborate metal piece, composed of wheels, mesh wiring and an assortment of intricate structures. Behind this, at right, sit stacks of paper, while a windowed wall lines the left
Among the Deep Sea Fishers, volume 57, issue 2 (July 1959)
No full textThe bargain that is confederation : editorial -- Travel note : editorial -- Journey from the igloo : editorial -- Bush flying for medicine / Marjorie G. Nichols -- "The stork" won't wait / Lesley Diack, S.R.N. -- Coast "young fry" (pictures) -- Double trouble for editors -- A regular summer traveler -- Labrador lighthouses, part I / Shirley S. Smith -- Coast-wise -- Our staff -- Alumni news -- The Grenfell Associations.Includes map: [Newfoundland and Labrador] (inside front cover).Among the Deep Sea Fishers: the Official Organ of the International Grenfell Association. This journal was published quarterly from 1903 to 1981 with the twofold purpose of providing "a record of Mission activities [and] also a strong and convincing appeal to every supporter and friend of Dr. Grenfell's work." The articles describe mission life, services and experiences. The Mission began under the auspices of the Royal National Mission to Deep Sea Fishermen but later a separate mission, the International Grenfell Association, was formed by Dr. Wilfred Grenfell
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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