Depinning transition of dislocation assemblies: pileup and low-angle grain boundary

We investigate the depinning transition occurring in dislocation assemblies. In particular, we consider the cases of regularly spaced pileups and low angle grain boundaries interacting with a disordered stress landscape provided by solute atoms, or by other immobile dislocations present in non-active slip systems. Using linear elasticity, we compute the stress originated by small deformations of these assemblies and the corresponding energy cost in two and three dimensions. Contrary to the case of isolated dislocation lines, which are usually approximated as elastic strings with an effective line tension, the deformations of a dislocation assembly cannot be described by local elastic interactions with a constant tension or stiffness. A nonlocal elastic kernel results as a consequence of long range interactions between dislocations. In light of this result, we revise statistical depinning theories and find novel results for Zener pinning in grain growth. Finally, we discuss the scaling properties of the dynamics of dislocation assemblies and compare theoretical results with numerical simulations.Comment: 13 pages, 8 figure

Depinning transition of dislocation assemblies: pileup and low-angle grain boundary

We investigate the depinning transition occurring in dislocation assemblies. In particular, we consider the cases of regularly spaced pileups and low angle grain boundaries interacting with a disordered stress landscape provided by solute atoms, or by other immobile dislocations present in non-active slip systems. Using linear elasticity, we compute the stress originated by small deformations of these assemblies and the corresponding energy cost in two and three dimensions. Contrary to the case of isolated dislocation lines, which are usually approximated as elastic strings with an effective line tension, the deformations of a dislocation assembly cannot be described by local elastic interactions with a constant tension or stiffness. A nonlocal elastic kernel results as a consequence of long range interactions between dislocations. In light of this result, we revise statistical depinning theories and find novel results for Zener pinning in grain growth. Finally, we discuss the scaling properties of the dynamics of dislocation assemblies and compare theoretical results with numerical simulations.Comment: 13 pages, 8 figure

The Ursinus Weekly, December 7, 1953

Prom to feature Johnny Austin, Sr. lord and lady • Wanamaker to give $1,000 scholarship • Sella resigns as senior prexy; Popowich unanimously chosen • Sixteenth Messiah performance to be held in Bomberger, Thursday • IRC to hear Chester Bowles at Bryn Mawr tonight • William S. Pettit named Dean of Ursinus College • MSGA hears student ideas at meeting • Raises revised by Stars and Players • Marge Merrifield wins hockey honor • Y plans party • Editorials: Honor at Ursinus; Maintenance mixup? • Cutting • Greek columns • Thespians present All my sons ; Reviewer notes fine performances • Pledge reveals fun and difficulties of informal Ursinus sorority initiation • Dorms eagerly anticipate vendors\u27 nightly visit • Hockey team ends season • JV Belles down Penn, W. Chester, Bryn Mawr • Soccermen lose to F&M; Season ends with party • Third team undefeated • Basketball season opens; Bears win, 84-66; 78-56 • Walker, Cox head 1954 football, soccer elevens • Dickinson downs Ursinus in football finale, 19-13 • Hockey-soccer game ends in 2-2 tie • Christmas vespers service to be held December 13 • Chemical society members visit chemical exposition • Truex speaks to pre-medders on opportunities in medicine • French Club holds program of vocal, piano music • Christmas dance plannedhttps://digitalcommons.ursinus.edu/weekly/1484/thumbnail.jp

Museography of immigration : investigation about exhibits' audience reception : the case of National Museum of the History of Immigration (la Cité Nationale de l'Histoire de l'Immigration) in Paris, France and the Immigration Museum in Melbourne, Australia

La Cité nationale de l'histoire de l'immigration n'a longtemps été qu'une idée pensée par le monde associatif et les chercheurs, qui désiraient qu'il y ait en France un lieu dédié à la mémoire de l'immigration. C'est au milieu des années 80 qu'émerge pour la première fois l'idée de créer un musée consacré à l'histoire de l'immigration, période qui se situe à l'intersection de l'ouverture à New York d' Ellis Island et en France dans le milieu académique, des premières thèses sur l'histoire de l'immigration. En 2007, la CNHI ouvre ses portes, et cette institution rompt avec la tradition du musée puisque d'une part, elle n'avait pas de collection et qu'elle a construit son patrimoine grâce à la société civile. D'autre part, c'est aussi un musée d'histoire et de société qui fait partie du label des Musées de France. Cette reconnaissance en tant que musée de France marque l'immigration comme faisant partie du patrimoine de la Nation, puisque tout ce que le musée acquiert entre dans les collections nationales. Notre étude se focalise sur la muséographie de l'immigration et l'évolution des croyances sur l'immigration, en interrogeant la réception des représentations de l'immigration à travers les expositions sur l'immigration en France et en Australie. En effet, l'Immigration Museum de Melbourne en Australie a ouverts ses portes au public en novembre 1998. Comme le musée parisien, il a été mis en place dans une volonté politique de créer un lieu fédérateur des cultures immigrantes d'Australie. Longtemps gouvernée par la While Policy, une politique d'immigration basée sur des critères raciaux, l'Australie ne reconnaît les différences ethniques qu'en 1973 suite à l'adoption d'une politique multiculturaliste par le Labour Party arrivé au pouvoir. Le musée de l'immigration à Melbourne devient un lieu symbolique où chaque Australien peut partager son histoire et faire des recherches généalogiques. Plus de dix ans après, ce musée connaît un grand succès dans l'un des Etats les plus multiculturels d'Australie. Notre recherche compare la réception des objets exposés sous le thème de l'immigration en France et en Australie afin de questionner les enjeux de la muséographie de l'immigration et de contribuer à mieux connaître les publics des musées d'immigration.The National Center for the History of Immigration (CNHI) was for a long time just an idea for civil society and academic researchers, both of whom wished a site dedicated to the memory of immigration in France. In the mid-eighties, the idea to create a space devoted to the history of immigration come clearly out of the shade for the first time, in the interim period between the opening of Ellis Island in New York and the first thesis about French History of Immigration. On October 10, 2007, the CNHI opened its doors, in Paris, and this national cultural institution breaks with previous tradition of the museum as firstly, it had no collection and secondly, the common cultural heritage is built with the help of donors and civil society. It is also a museum society and a museum of history that has the Ministry of Culture and Communication « Museum of France » label. The recognition of the CNHI as a French museum means that immigration is now part of French heritage since all that was acquired by the museum thus become part of national collections. The CNHI was created by the two overarching themes of tradition and innovation : as a National Museum that seizes upon a complex social and historical phenomenon : immigration. My research combines both conceptions of museography and the evolution of ideas by investigating exhibits' audience reception in France and Australia. Immigration Museum in Melbourne opened in 1998 by the political will to create a unifying place to culturally of race, it was not until 1973 that policy of multiculturalism openly promoting diversity is established in Australia. The State of Victoria created a space where people could share their story and provide guidance in genealogical research. More than ten years after, the museum is especially popular in one of the most multicultural State of Australia, State of Victoria. My research contributed to improve the knowledge on issues about musealizing immigration, by studying the impact of the display of immigration on the audience