Natural ageing is known to have a negative effect on the formability and bake-hardening response of Al-Mg-Si alloys. This is attributed to the formation of Mg and Si clusters during natural ageing. The clustering process was the subject of many studies in the literature, however, the formation mechanism and kinetics of it, continues to be poorly understood. The aim of this project is to shed some light on the cluster formation mechanism and measure clustering kinetics at low temperatures. A series of electrical resistivity measurements, positron annihilation lifetime spectroscopy and hardness tests were performed on samples aged over the temperature range of -20 to 50°C following solution treatment at temperatures of 525 and 560°C. A very good correlation between the results of various techniques was observed. In addition, three different stages in the clustering process were detected. Not surprisingly it was found that the excess quenched-in vacancies are the key players in the cluster formation process. In the first stage, annihilation of near-sink vacancies occurs while other vacancies start to bind with solute atoms and form clusters. In the second stage, clustering continues to take place but its rate slows down since the effective diffusion coefficient of vacancies decreases as they bind with more solute. Finally, the clustering process enters the third stage with much slower kinetics. Interestingly, positron annihilation lifetime also reaches a constant value at the beginning of stage III which suggests the stabilization of vacancies. Two hypothesis were then developed to explain the existence of stage III: one based on the immobilization of vacancies due to the increased binding with solute atoms and another one which considers the overlapping of solute diffusion profiles around the clusters. Finally it was shown that the resistivity change in stage II can be used to find the activation energy of clustering which is calculated to be approximately 46 kJ/mol. This is very close to the migration energy of vacancies and Mg atoms. Thus it was concluded that migration of these species is the major rate controlling parameter for the clustering process. / Thesis / Master of Applied Science (MASc)

This study investigated the role of Sic particles in the mechanical behaviour of a metal matrix composite (Al-SiC). Measurements of the development and magnitude of internal stresses were performed from Bauschinger experiments in the aluminum matrix A-356 reinforced with the Sic particles. The behavior of the Al matrix itself was also analyzed. The level of internal stresses in the particulate reinforced composite was found to saturate after 0.9% plastic strain and after 1.3% in the unreinforced matrix. The initial development of the unrelaxed internal stresses was analyzed using both microscopic and macroscopic models of the load-bearing role of the Sic particles. The Sic particles were found to have little influence on the plastic flow of the composite beyond the initial plastic deformation as the size and distribution of the Sic is very non-uniform. The effect of the Sic phase was compared to continuous fibers embedded in a metallic matrix. A model system of pure copper reinforced with continuous tungsten fibers was used for this purpose. The effect of the internal stresses on the dimensional stability of the particulate reinforced and the unreinforced matrix was also investigated. The generation of dislocations arising from the thermal cycling of those materials was also analyzed by reference to the increase in flow stress observed after thermal cycling and from a model based on dislocations production due to the difference in coefficient of thermal expansion of the phases. / Thesis / Master of Engineering (ME)

No description available.

L’étude de la grammaire arabe est restée trop longtemps ancrée à la période fondatrice de cette discipline (IIᵉ-IVᵉ/VIIIᵉ-Xᵉ siècles). Cette thèse veut apporter une contribution sur des aires moins parcourues, telles la période post-classique et les périphéries du monde arabo-musulman ou, plus précisément, ses marges occidentales. Le point de départ est représenté par un Persan du IVᵉ/Xᵉ siècle installé à Damas, ʾAbū al-Qāsim al-Zaǧǧāǧī, un des grammairiens arabes les plus connus aujourd’hui mais n’ayant pas joui, à son époque, d’un succès immédiat. Ce succès s’est construit petit à petit grâce à l’un de ses traités, le Kitāb al-Ǧumal fī al-naḥw. Après une présentation du grammairien et du texte en question, cette étude essaie de suivre la diffusion du Ǧumal à travers les régions et les époques depuis le moment de sa rédaction. Cette recherche mène en al-Andalus : alors que cet ouvrage semble être délaissé en Orient, il est adopté par les savants andalous comme l’un des textes de base pour les études grammaticales. L’analyse des chaînes de transmission du Ǧumal et la recherche de ses commentaires montrent que ce traité n’a pas seulement été le texte grammatical principal dans cette périphérie du monde arabo-musulman, mais qu’il a aussi fini par devenir une sorte de miroir de l’histoire et de l’identité andalouses. En commençant le voyage au IVᵉ/Xᵉ siècle, il est possible de parcourir l’histoire de ce texte de manière presque ininterrompue jusqu’à nos jours : d’Orient en al-Andalus au moment de la formation de la culture andalouse, puis d’al-Andalus au Maghreb (et en Orient) avec les vagues d’émigration andalouses, pour finir avec son editio princeps de 1927 à Alger. / Scholars in the Arabic Grammatical Tradition have mainly been focusing their attention on the formative stage of the Arabic grammatical theory (2nd-4th/8th-10th centuries). This dissertation aims at broadening the scope and is intended to contribute to our knowledge of this discipline at the post-classical period and in the western periphery of the Islamic world.The starting point of research is represented by a 4th/10th century grammarian of Persian origin who settled in Damascus: ʾAbū al-Qāsim al-Zaǧǧāǧī. Nowadays he is one of the best-known Arabic grammarians, but that was not the case in the beginning. Indeed his fame grew steadily thanks to one of his treatises, the Kitāb al-Ǧumal fī al-naḥw. The presentation of al-Zaǧǧāǧī and of his book sets the frame for the study, whose main focus is to trace the history of this text through time and space. This enquiry leads to al-Andalus: whereas the Ǧumal seemed to be abandoned in the Islamic East, it was adopted by Andalusian scholars as one the main texts for grammatical studies.The analysis of its chains of transmission and the presentation of all of its commentaries show not only that this treatise was the main grammatical text in this periphery of the Islamic world, but even that it came to be a sort of mirror of Andalusian history and identity.The journey of this book starts at the 4th/10th century and may be followed almost uninterruptedly until today: imported to al-Andalus from the Islamic East during the formative stage of Andalusian culture, it was then brought to Maghreb thanks to Andalusian emigration flows and was eventually edited in Algiers in 1927.

The enactement of the Energy Policy and conservation Act of 1975, led to a paradigm shift in material selection and design in the automotive industry. The net effect was an increased focus by the automotive industry toward the use of light metals leading for the reduction of weight and hence, the dependence of imported oil. Increasing use of aluminum was a transition in that direction. However, raw aluminum on an average is 1.5 - 2 times as expensive as steel. Near net shape manufacturing processes (Die casting, Thixo-forging, etc) provided the much needed competitive advantage vis-à-vis steel / iron parts by permitting the manufacturing of Al components. Semi solid processing involves the net shape manufacturing of alloys in a two phase region (liquid + solid). The reduced turbulence (during casting), less entrapped gases and lower operating temperatures (processes below the liquidus) make semi solid processing ideal for the manufacturing of high integrity Al parts. Traditionally, semi solid processing involved the heating of billets to a two phase region (called Thixcasting). Rheocasting is a new semi solid processing technique wherein the alloy is cooled from a liquid state (a combination of controlled heat / nucleation and growth phenomena) to yield structures similar to the Thixocasting process. Rheocasting or Slurry-On-Demand is in its early stages of development (the first industrial prototype of rheocasting was invented in the late 1990's) and forms the central point of interest in this work. Much research is underway around the globe to understand the controlling mechanism as well as the structure - property relationships in rheocast parts, primarily limited to the hypoeutectic Al-Si alloys (less than 12.6% Si). This work is dedicated in the development of novel methods for the rheocasting of hypereutectic Al-Si alloys (greater than 12.6% Si) and Al based wrought alloys (alloys with Cu, Zn, Mg and Si as alloying elements). The thesis presents the problems associated with microstructure control of hypereutectic Al-Si (primary Si coarsening and accelerated growth) and Al based wrought alloys (dendritic structures and hot tearing) with currently available technologies. Novel processing techniques are presented for the casting of hypereutectic Al-Si alloys and Al based wrought alloys with a combination of industrial trials and a through analysis of the underlying mechanisms.

Le quartier d'al-Mïdan est un exemple judicieux pour présenter l'histoire et le développement de l'expansion urbaine extra-muros de la ville de Damas. En effet, son expansion s'est poursuivie sans interruption au fil des siècles. Longeant la Rue principale vers la Terre Sainte, l'Égypte et la Palestine, ce quartier a été divisé en trois parties (Nord, Centre et Sud) afin d'en faciliter son étude. Le quartier s'est développé à partir des villages des premières tribus arabes installées aux alentours de la muraille (VIIe et VIII siècle). La partie Nord a été le premier secteur du quartier à connaître un vrai essor dans son urbanisation jusqu'à l'époque ayyoubide (570-658/1174-1260) où le Musalla a été transformé en mosquée (en 606/1211) et où la partie centrale a connu un noyau d'urbanisation. A l'époque Mamelouke (658-923/1258-1516), le village al-Qubaybat est apparu dans le Sud avec sa mosquée, la Mosquée al-Karïmï (en 718/1318). Par la suite, la Mosquée de Manjak a été érigée (avant 826/1423) dans le secteur Central qui a intégré la partie Nord. Suite à cela, al-Qubaybat a perdu son indépendance en intégrant l'unité spatiale du quartier avant l'arrivée des ottomans (en 923/1516). L'étude architecturale de l'ensemble des monuments du quartier d'al-Mïdan révèle une identité spécifique avec, d'une part, l'absence totale de madrasa et, d'autre part, la présence de mausolées mamelouks à deux coupoles. Par ailleurs, le quartier présente le seul exemple dans l'architecture damascène d'un édifice proche du type« sabïl- maq'ad », bien connu au Caire d'époque mamelouke. Les sources historiques et les documents écrits des archives fournissent des listes importantes de monuments du quartier disparus de nos jours. Cela s'ajoute à la liste issue des travaux sur le terrain et permet d'avoir une vue plus complète sur l'histoire de l'urbanisation du quartier. La société a été composée de plusieurs classes: les notables (al-Kubartiou al-A 'yiin) qui ont collaboré avec les militaires pour contrôler les peuple (al-'Amma), sans oublier les grand commençants et les milices locales appelées « al-Zu 'ur ». Le pouvoir était représenté par un walï, qui avait la responsabilité de le contrôler, d'y maintenir l'ordre et de collecter les impôts. Ce dernier était soutenu dans sa mission par deux autres personnages : le Shaykh al-hara, qui en général était choisi par le pouvoir parmi les élites ou les personnes puissantes du quartier, et le 'Arif al-hara, qui était un des chefs des milices locales « al-Zu 'ur ». / The district of al-Mïdan is a perfect example to present the history and development of the extramural expansion of the city of Damascus. Indeed, its expansion has continued without interruption for centuries. On both sides of the main road to the Holy Land and Egypt, the area was divided into three sections (North, Central and South) to facilitate its study. The district started to develop from the villages of the first Arab tribes settled a round the wall (seventh and eighth century AD). The northern part was the first sector to experience a real momentum in its urbanization in the Ayyubid period (570-658 / 1174-1260), where the Musalla was converted into a mosque (in 606/1211) and the central part became the core of urbanization. ln Mamluk times (658-923 / 1258-1516), the town of al-Qubaybat appeared in the South with its al­Karimï mosque (in 718/1318). Thereafter, the Jamï Manjak was erected (before 826/1423) in the central area which then incorporated the northern part. Subsequently, al-Qubaybat lost its independence by incorporating into the spatial unity of the area before the arrival of the Ottomans (in 923/1516). The architectural study of the monuments in the district of al-Mïdan reveals a specific identity, total lacking madrasas on the one hand, and on the other band, including: Mamluk mausoleum with two domes. Furthermore, the district has the only example in Damascus of a building approximating to the type "sabïl­maq'ad", well known under the Mamluks in Cairo. The historical sources and written documents of the archives provide important lists of monuments today disappeared. This can be added to the list of the monuments studied and provides a more comprehensive view of the area's urbanization. The social organization was composed of several classes: the notables (al-Kubariï or al-a’yan) who worked with the military to control the people (al-'Amma), without forgetting the well known merchants and local militias called "al-Zu'ur ". The authority was represented by the walï, who was responsible for control, maintaining order and collecting taxes. The walï was supported in his mission by two other persons: Shaykh al-hara, who in general was chosen by the authorities among the elites or powerful people in the district, and the 'Arif al- hara, who was a leader of local militias "al-Zu'ur".

The Kitāb al-Aghānī (the Book of Songs) is one of the most important sources for Arabic literature and history. While its compiler, Abū al-Faraj al-Iṣfahānī (died after 356/967), is generally viewed as a “Zaydī Shīʿī”, no study has engaged in depth with the manifestation of his sectarian perspective in the Aghānī. This thesis addresses the question of whether al-Iṣfahānī’s sectarian perspective can be discerned in the Aghānī via literary analysis based primarily upon redaction criticism. By examining the compiler’s interventions (which took place by means of selecting, repeating, and juxtaposing source material, as well as by his comments and editorial remarks), this thesis argues that al-Iṣfahānī indeed presents past people and events central to the Shīʿī worldview in accordance with his sectarian affiliation. Furthermore, this thesis questions the label “Zaydī” that has been attached to al-Iṣfahānī. Based on textual analyses of the Aghānī, as well as evidence from his Maqātil al-Ṭālibīyīn (“The Ṭālibid Martyrs”) and other evidence for the tenth-century context, this thesis suggests that al-Iṣfahānī’s religious thought can be construed as a “mild” form of Shīʿism ― in the sense that it does not entail belief in a specific lineage of imams and repudiation of most of the Companions including the first three caliphs ― but cannot necessarily be identified with any sect, as set down in the heresiography. It is also suggested that this kind of Shīʿism may have been promoted by al-Iṣfahānī’s patron, the Būyid vizier, Abū Muḥammad al-Muhallabī (291–352/903–963) in the complex sectarian context of mid-tenth century Iraq. This thesis comprises seven chapters. Chapters One and Two introduce the life of the compiler, the wider historical context, the Aghānī, its textual problems, and its overarching structure. These two chapters lead to three conclusions: first, the Aghānī, in all likelihood, was dedicated to Abū Muḥammad al-Muhallabī; second, the view that al-Iṣfahānī was a Zaydī is untenable; third, it is very likely that the Aghānī retains its original form (as designed by al-Iṣfahānī). Chapter Three investigates the sources used by al-Iṣfahānī in the Aghānī with regard to their transmission in order to establish that the published text can indeed be subjected to redaction criticism for the purpose of better understanding the compiler’s agenda (or agendas). Chapters Four and Five present the results of the literary analysis of the Aghānī, which demonstrate the articulation of a Shīʿī past in the Aghānī, as well as highlighting the limits of redaction criticism and al-Iṣfahānī’s other editorial concerns. Building upon Chapter Five, which concludes that the Aghānī reflects al-Iṣfahānī’s sectarian vision, Chapter Six characterizes al-Iṣfahānī’s Shīʿī beliefs by examining his treatment of Ghulāt, Imāmīs, Sunnīs, ʿAlids, and the Companions, including the first three caliphs. Chapter Seven puts the results of the analyses into their historical context, specifically in light of the career of his patron, al-Muhallabī. The Conclusion outlines the key findings of this thesis, with remarks on potential avenues for future research.

Une fois la théorie des équations quadratiques établie, les algébristes arabes orientent leurs recherches vers d'autres sujets. À la fin du Xe siècle l'un d'eux, le mathématicien al-Karajī, choisit d'explorer les relations entre arithmétiques et algèbre, et développe un système cohérent et exhaustif de règles de calcul pour les entités algébriques. Ce faisant, il inaugure une nouvelle tradition de recherche d'arithméticiens-algébristes qui visent à féconder l'algèbre avec l'arithmétique, et inversement. La notion centrale de cette tradition est celle d'opération et son objectif est de faire en sorte que l'algébriste puisse opérer sur les quantités inconnues comme l'arithméticien opère sur les connues. La recherche d'al-Karajī est ensuite perfectionnée au XIIe siècle par al-Samaw'al. Le travail du mathématicien persan al-Zanjānī (XIIIe siècle) s'inscrit clairement dans cette tradition de recherche, et son Qisṭās al-muʻādala reprend fidèlement les textes karajiens. Dans ce traité, al-Zanjānī présente la théorie du calcul algébrique, il compose une longue collection de problèmes et conclut son écrit avec un chapitre entièrement consacré à l'analyse indéterminée. Le traité était, jusqu'à maintenant, inédit. Notre édition critique est suivie d'une traduction en français et précédée d'une analyse historique, philologique et mathématique du texte. Cette analyse vise à mettre en évidence les aspects les plus significatifs de l'algèbre d' al-Zanjānī, ainsi que de la tradition à laquelle ce dernier appartient / Once the theory for second degree equations was established, algebraists redirected their interests to new topics. By the end of tenth century, one algebraist, the mathematician al-Karajī, chose to investigate the interaction between arithmetic and algebra, and began to create a coherent and exhaustive system of rules for calculating with algebraic entities. His work gave birth to a new tradition of arithmetician-algebraists, whose aim was to improve algebra with the help of arithmetic and vice versa. The focus of this tradition was on the notion of operation, and its aim was to make the algebraist able to manipulate unknown quantities like the arithmetician manipulates known ones. Al-Karajī's research was then improved by the twelfth-century scholar al-Samaw‘al. In the thirteenth century, the Persian mathematician al-Zanjānī followed this same tradition, and his Qisṭās al-muʻādala accurately recalls and elaborates upon al-Karajī's work. Al-Zanjanī presents his theory for algebraic computations, composes a long collection of problems, and concludes his treatise with a chapter on indeterminate analysis. Al-Zanjanī's treatise was unpublished until now. Our critical edition of the text is followed by a translation into French and preceded by an historical, philological and mathematical commentary of the text. This commentary aims to underline the most significant aspects of al-Zanjanī's algebra and of the tradition to which he belonge

To evaluate potential uses for friction stir welding in additive manufacturing, two separate parts were fabricated, one of 2195-T84 and the other 2219-T87, utilizing fixed pin techniques and additive lap welds. The parts were cut into samples, artificially aged and subjected to Rockwell hardness (HRB), Vickers hardness, micrographic photography, and metallographic imaging on both pre- and post- heat treatment. Additionally, tensile testing was performed on the heat-treated samples. A comparisons of test results showed a minimal increase in the yield strength of the 2195-T84 samples compared to as-welded tensile results obtained from a previous project. The ultimate tensile strength was reduced by approximately 16%. Further testing will be required to determine the nature of this reduction. No previous results were available for the as-welded 2219-T87, but UTS of the artificially aged samples was approximately 91% that of the parent material.

El presente estudio “La Calidad del Servicio Tercerizado en la Banda Ancha de Telefónica del Perú SAA” tiene por finalidad investigar la calidad de servicio que brinda el personal técnico de las Empresas Colaboradoras de Telefónica del Perú (TDP), encargado de las atenciones en casa de los clientes de las instalaciones o reparaciones de los servicios de la Banda Ancha, es decir del servicio denominado comercialmente Speedy, de acceso a la Internet; para determinar su contribución a la satisfacción del cliente. Para tal efecto, hemos efectuado una encuesta a dichos técnicos y un trabajo de gabinete en base a encuestas de satisfacción del cliente de la propia Telefónica, para validar desde la perspectiva del cliente, los factores de calidad, que refieren los técnicos brindan para la satisfacción del cliente. / This study “Quality of Outsourced Service in Broadband at Telefónica del Perú SAA” has as purpose to research the quality of the service rendered by technical personnel from Telefónica del Perú (TDP) Collaborating Companies, in charge of give service to the clients in their own homes in installations or repairs in Broadband services, meaning the service with the commercial name of Speedy, for access to the Internet, to determine its contribution to customer satisfaction. For such purpose, we have made a poll with such technicians and a cabinet work based on customer satisfaction polls from Telefónica itself to validate, from the customer’s experience, the quality factors that the technician say they give for customer satisfaction.