Network Coding is a new possibility to transmit data through a network. By combining different packets instead of simply forwarding, network coding offers the opportunity to reach the Min-Cut/Max-Flow capacity in multicast data transmissions. However, the basic schemes are vulnerable to so-called pollution attacks, where an attacker can jam large parts of the transmission by infiltrating only one bogus message. In the literature we found several approaches which aim at handling this kind of attack with different amounts of overhead. Though, the cost for a specific secure network coding scheme highly depends on the underlying network. The goal of this paper is on the one hand to describe which network parameters influence the efficiency of a certain scheme and on the other hand to provide concrete suggestions for selecting the most efficient secure network coding scheme considering a given network. We will illustrate that there does not exist “the best” secure network scheme concerning efficiency, but all selected schemes are more or less suited under certain network topologies.

Probabilistic-Write/Copy-Select (PWCS) is a novel synchronization scheme suggested by Nicholas Mc Guire which avoids expensive atomic operations for synchronizing access to shared objects. Instead, PWCS makes inconsistencies detectable and recoverable. It builds on the assumption that, for typical workloads, the probability for data races is very small. Mc Guire describes PWCS for multiple readers but only one writer of a shared data structure. In this paper, we report on the formal analysis of the PWCS protocol using a continuous-time Markov chain model and probabilistic model checking techniques. Besides the original PWCS protocol, we also considered a variant with multiple writers. The results were obtained by the model checker PRISM and served to identify scenarios in which the use of the PWCS protocol is justified by guarantees on the probability of data races. Moreover, the analysis showed several other quantitative properties of the PWCS protocol.

Supply chain disruptions, ranging from epidemics to geopolitical tensions, have been especially evident in recent years and have consequently become a hot topic in both boardrooms and academic literature. Supply chain resilience (SCR) denotes the ability to prepare, respond, recover, and facilitate growth during disruptions and is usually thought of as consisting of several enablers. Initial evidence suggests that one such enabler could be analytics, which broadly refers to the processing of data to support decision-making. This thesis aims to explore the use of analytics for SCR. The research design comprise one conceptual component followed by two empirical components consisting of a survey and interviews. The findings reveal six application areas for analytics in SCR. Three paths to SCR are also identified in terms of configurations of analytics and other SCR enablers, only one of which does not seem to be contingent on the level of supply chain complexity. Finally, obstacles to the use of analytics were identified. Clear consensus was noted for low data availability and/or quality as a major obstacle to SCR, while a somewhat consensus existed concerning the hindrance to quick decision-making, lack of a data-driven culture, and insufficient benefits and/or use. The thesis contributes to the nascent stream of research on the use of analytics and SCR by complementing individual observations with broader and deeper insights through the spectrum of application areas, configurations of analytics and complementary SCR-enablers, and finally, obstacles. For practitioners, the thesis provides insights into using analytics as a potential enabler for SCR. Firms can evaluate their current use of analytics for SCR and adjust their set of application areas and configurations of SCR-enablers as per the options outlined in the findings to better align with their specific needs and prerequisites. Finally, guidance is provided on what obstacles to be cognizant of and attempt to mitigate. / Störningar i försörjningskedjor, orsakade av händelser såsom pandemier och geopolitiska spänningar, har varit särskilt påtagliga under de senaste åren och har därmed blivit ett hett ämne både i näringslivet och akademin. Begreppet Supply chain resilience (SCR) avser försörjningskedjans förmåga att förbereda sig, reagera, återhämta sig och stödja tillväxt under sådana störningar. Det anses vanligtvis bestå av flera möjliggörare. Initiala bevis i litteraturen tyder också på att en av dessa möjliggörare kan vara analytics, som i stora drag betyder bearbetning av data för att stödja beslutsfattande. Denna avhandling syftar till att utforska användningen av analytics för SCR. Forskningsmetoden bestod av en konceptuell studie, följt av två empiriska studier i form av en enkät och intervjuer. Resultaten visar sex tillämpningsområden för analytics med avseende på SCR. Dessutom identifierades tre vägar till SCR när det gäller konfigurationer av analytics och andra SCR-möjliggörare, varav endast en konfiguration är oberoende av försörjningskedjans komplexitetsnivå. Slutligen identifierades hinder för användning av analytics för SCR. Det fanns en tydlig konsensus kring låg tillgänglighet och/eller kvalitet på data, medan det fanns viss enighet om hinder för snabba beslut, bristen på en kultur att basera beslutsfattande på analytics och slutligen otillräcklig nytta och/eller användning. Avhandlingen bidrar till forskning om användningen av analytics för SCR genom att komplettera enskilda observationer med bredare och djupare insikter om spektrumet av tillämpningsområden, konfigurationer av analytics och kompletterande SCR-möjliggörare, och slutligen, hinder. För praktiker ger avhandlingen insikter i att använda analytics som en potentiell möjliggörare för SCR. Företag kan utvärdera sin nuvarande användning av analytics för SCR och förändra tillämpningsområden och konfigurationer av SCR-möjligare enligt de identifierade alternativen för att bättre tillgodose sina behov och förutsättningar. Slutligen ges vägledning om vilka hinder man bör vara medveten om och försöka mildra.

Die Dresdner Werkzeugmaschinen-Fachseminare sind ein Forum zu ausgewählten Spezialthemen der Entwicklung und Nutzung von Werkzeugmaschinen. Das 16. WZM-Fachseminar berichtetet inhaltlich detailliert von aktuellen Arbeiten im Rahmen des DFG-Sonderforschungsbereiches "Thermo-Energetische Gestaltung von Werkzeugmaschinen" (SFB/TR 96) an den Standorten Dresden, Aachen und Chemnitz. Die Fachbeiträge berichten über experimentelle und modellgestützte Analyse von Wärmequellen und -übertragung in spanenden Werkzeugmaschinen sowie zu Lösungsansätzen zur Korrektur und Kompensation der thermo-elastischen Verlagerungen.

We consider the problem of secure communications in a Gaussian two-way relay network where two nodes exchange confidential messages only via an untrusted relay. The relay is assumed to be honest but curious, i.e., an eavesdropper that conforms to the system rules and applies the intended relaying scheme. We analyze the achievable secrecy rates by applying network coding on the physical layer or the network layer and compare the results in terms of complexity, overhead, and efficiency. Further, we discuss the advantages and disadvantages of the respective approaches.

Preventing the success of active attacks is of essential importance for network coding since even the infiltration of one single corrupted data packet can jam large parts of the network. The existing approaches for network coding schemes preventing such pollution attacks can be divided into two categories: utilize cryptographic approaches or utilize redundancy similar to error correction coding. Within this paper, we compared both paradigms concerning efficiency of data transmission under various circumstances. Particularly, we considered an attacker of a certain strength as well as the influence of the generation size. The results are helpful for selecting a suitable approach for network coding taking into account both security against pollution attacks and efficiency.

La présente recherche collaborative vise à étudier les pratiques de lecture à haute voix d’enseignantes expertes et leur influence sur le développement de l’habileté des élèves du préscolaire à faire des inférences. Plus précisément, nous décrivons les interventions, lors des lectures à haute voix, de quatre enseignantes expertes que nous avons formées pour travailler la compréhension inférentielle et les comparons à celles de deux enseignantes expertes non formées (objectif 1). Puis, nous examinons l’influence de leurs pratiques de lecture à haute voix sur le développement de l’habileté à faire des inférences de leurs élèves (n=92) (objectif 2). Enfin, nous nous intéressons, à titre exploratoire, au potentiel de la recherche collaborative comme voie de développement professionnel des enseignants (objectif 3). Afin d’atteindre nos objectifs, nous avons observé les enseignantes à quatre reprises, lors de lectures d’albums de littérature de jeunesse. Les données obtenues à partir de ces pratiques observées ont été complétées par celles issues des pratiques déclarées des enseignantes pour toute la durée de la recherche (neuf semaines). De plus, nous avons évalué l’habileté à réaliser des inférences des élèves de ces six enseignantes à deux reprises, au début et à la fin de la recherche. Finalement, les enseignantes ont rempli deux questionnaires écrits sur l’impact de cette recherche sur leurs pratiques, l’un à la fin de la recherche et l’autre deux ans après celle-ci. Nos résultats indiquent que si toutes les enseignantes travaillaient les inférences, il existe cependant des différences notables dans leur façon de mener ce travail. Trois des enseignantes formées (enseignantes 1, 2 et 3) ont majoritairement privilégié la co-élaboration du sens des épisodes implicites et se sont montrées très efficaces pour soutenir leurs élèves dans ce travail de construction du sens. L’autre enseignante formée (enseignante 4), en raison d’une appropriation difficile du contenu de la formation, n’est pas parvenue à offrir à ses élèves un étayage adéquat, malgré ses nombreuses tentatives pour les amener à faire des inférences. Les enseignantes non formées (enseignantes 5 et 6) ont, quant à elles, misé plus fréquemment sur la transmission du sens des épisodes implicites et ont également soutenu moins efficacement leurs élèves dans l’élaboration du sens. Ces différences dans la façon de travailler les inférences se sont répercutées sur la progression des élèves entre le début et la fin de la recherche. Ceux des enseignantes 1, 2 et 3 obtiennent des résultats significativement supérieurs à ceux des trois autres enseignantes. Ainsi, il ne suffit pas de travailler les inférences lors des lectures à haute voix pour assurer la progression des élèves. D’autres facteurs revêtent aussi une grande importance : le choix d’oeuvres de qualité, l’engagement des élèves dans les discussions pour co-élaborer le sens et l’étayage adéquat de l’enseignant. Enfin, il semblerait que l’activité réflexive suscitée lors d’une participation à une recherche collaborative et le soutien offert par l’étudiante-chercheuse aient donné aux enseignantes la possibilité d’apporter des changements durables dans leurs pratiques. En ce sens, la recherche collaborative paraît être une voie prometteuse pour contribuer au développement professionnel des enseignants. / This collaborative research is an attempt to study expert teachers' reading aloud practices and their impact on the development of preschool students’ ability to make inferences. First, the interventions of four expert teachers specifically trained to work inferences while reading aloud are described and compared with those of two non trained expert teachers (objective 1). Next, the impact of all teachers’ practices on the development of their students’ ability to make inferences (n=92) is examined (objective 2). Finally, we look into collaborative research as a way to support professional development for teachers (objective 3). In order to attain our objectives, we observed participant teachers four times while they were reading children’s books. Data gathered from those observations were completed with other data provided by the teachers about their practices over a nine-week period. Moreover, the ability of the students to make inferences was assessed twice: once at the beginning and once at the end of the research. Teachers also completed two written questionnaires, one at the beginning and the other 2 years after the end of this research, concerning the impacts of their participation in this research on their practices. While all teachers worked inferences with their students, our results showed that there are significant differences in the way they do it. Three of the trained teachers (number 1, 2, and 3) predominantly put emphasis on co-elaboration of the implicit episodes’ meaning and gave their students appropriate scaffolding. Because she found it difficult to assimilate training contents, the other trained teacher (number 4) failed - not without numerous attempts - to offer the same kind of scaffolding. As for the two non trained teachers (number 5 and 6), they gave preference to the transmission of the implicit episodes’ meaning, and supported their students less efficiently when they tried to elaborate it. The differences in how the work on inferences was done had an impact on students’ progression from the beginning to the end of the research. Three of the trained teachers’ students had significantly superior results in comparison to the others’. Therefore, a specific work on inferences only does not ensure that students will make progress. There are other important contributing factors: choosing quality books, students’ involvement in discussions in order to co-elaborate the text’s meaning, and appropriate scaffolding from the teacher. Finally, according to our results, a participation in a collaborative research, which promotes reflexivity and offers coaching, seems to give the teachers the opportunity to bring about long-term changes in their practices. In consequence, a participation in that type of research appears to contribute to teachers’ professional development.

The concept of biodiversity – the phenotypic and genotypic variation among organisms – is central to conservation biology. There is growing recognition that biodiversity does not exist in isolation, but rather is intrinsically and evolutionarily linked to cultural diversity and indigenous knowledge systems. In Canada, caribou (Rangifer tarandus) occupy a central place in the livelihoods and identities of indigenous people and display substantial variation across their distribution. However, quantifying caribou intraspecific variation has proven challenging. Interdisciplinary approaches are necessary to produce effective species characterizations and conservation strategies that acknowledge the interdependent relationships between people and nature in complex social-ecological systems. In this dissertation I use multiple disciplinary traditions to develop comprehensive and united representations of caribou variation through an exploration of population genetics, phylogenetics, traditional knowledge, language, and visual approaches in the Sahtú region of the Northwest Territories, Canada. First, I examine caribou variation through analysis of population genetics and the relationships Dene and Métis people establish with animals within bioculturally diverse systems. Next, I focus on how the Pleistocene glacial-interglacial cycles have shaped the current patterns of caribou phylogeographic lineage diversification. Finally, I explore how art can be used to facilitate cross-cultural collaboration and externalize the unique heterogeneity of biocultural diversity. The results demonstrate a broad scale understanding of the distribution, spatial organization, and the degree of differentiation of caribou populations in the region. I found evidence for caribou population differentiation that corresponds to the caribou types recognized by Dene people: tǫdzı “boreal woodland caribou,” ɂekwę́ “barren-ground caribou,” and shúhta ɂepę́ “mountain caribou.” Phylogenetic results reveal that in their northern margin the boreal ecotype of woodland caribou evolved independently from the northern Beringian lineage in contrast with southern boreal caribou which belong to the sub-Laurentide refugia lineage. In addition, I demonstrate how art can be used improve communication, participation, and knowledge production among interdisciplinary research collaborations and across language and knowledge systems. A collaborative process of research that facilitates łeghágots'enetę “learning together” has the potential to produce sustainable conservation solutions, develop efficient and effective wildlife management policies, and ensure caribou remain an important part of the landscape. / February 2017

La crise éducative et économique mondiale génère un besoin de revoir les finalités éducatives et de réformer la pensée. « Les sept savoirs nécessaires pour l’éducation du futur », d’Edgar Morin, visent un humanisme démocratique et scientifique. C’est dans cette optique, et avec ce cadre épistémologique, que nous avons constitué une recherche collaborative internationale sur la formation de formateurs, au sein du mouvement de l’École Moderne. Une confrontation coopérative interculturelle a commencé, dans un premier temps, par une observation participante armée dans 5 pays européens, afin de travailler la dimension macro et méso de leurs systèmes éducatifs, et pour développer un réseau international qui a officiellement vu le jour lors de la rencontre physique d’enseignants et de formateurs de différents pays européens en 2009. Elle a révélé, au niveau méso et micro, des points aveugles, et elle a engendré, dans un second temps, une autoformation coopérative, grâce à l’émergence de nouvelles didactiques professionnelles socioconstructivistes. Celles-ci ont été mises en œuvre dans le cadre de la formation d’enseignants en février 2010, à Valencia, et de formateurs, en juillet 2010, à Nantes, avec un public hétérogène issu de 3 continents. Fondées sur l’articulation entre « tâtonnement expérimental » et coopération, elles représentent un lien entre éducation, formation et recherche. Elles développent la capacité à travailler en équipe, la créativité et la réflexivité. Ce travail de thèse montre que la diversité culturelle peut être source de richesse, d’intelligence collective internationale, et d’apprentissage transformateur, développant un « ingenium » transférable dans différents contextes, notamment en matière de formation de formateurs. / The educational and economic crisis generates a need to re-examine the education purposes and to reform the thought. “The seven knowledge necessary to educate the future”, (Morin E., 1999), aims at a democratic and scientific humanism. We constituted an international collaborative research on teacher training, supported by this philosophical and epistemological framework, within the the Modern School movement. An intercultural co-operative confrontation started, initially, by a participating observation in 5 European countries, in order to work macro and meso dimensions of their educational systems, and to develop an international network which officially came out during a physical meeting of teachers and trainers from various European countries, in 2009. It revealed blind points, on meso and micro levels, and generated a co-operative self-directed training, in a second step, thanks to the emergence of new professional socioconstructivist didactics, within the framework of teachers training, in February 2010, in Valencia, and trainers training, in July 2010, in Nantes, with a heterogeneous public of 3 continents. Based on the articulation between “experimental probing” and co-operation, they connect education, training and research. They develop ability to work in team, creativity and reflexivity. This thesis shows that cultural diversity can generate empowerment and international collective intelligence, transformative learning, developing a transferable “ingenium” in various contexts.

O objetivo principal desta pesquisa orientou-se pela intenção de dar visibilidade à produção brasileira em Educação de pesquisas tipo pesquisa-ação / investigação-ação, focalizando, sobretudo, a pesquisa-ação colaborativa. Essas concepções de pesquisa estimulam a aproximação entre professores e pesquisadores, por meio da colaboração em processos investigativos desenvolvidos com, para e pelos professores sobre as práticas escolares. Na maioria dos casos, tais pesquisas foram desenvolvidas nas escolas. Este estudo foi desenvolvido em quatro estágios: O primeiro é constituído por um estudo bibliográfico que objetivou indicar os teóricos que influíram nessa modalidade de pesquisa em seu enraizamento no Brasil. Para isso, tomamos alguns autores: Saul, Freire, Thiollent, Barbier, Costa, André, Nóvoa, Geraldi, Fiorentini, Pereira, Stenhouse, Elliott, Carr, Kemmis e Zeichner. Num segundo momento, fizemos um mapeamento das dissertações e teses tipo pesquisa-ação / investigação-ação produzidas nos Programas de Pós-Graduação em Educação do Brasil no período entre 1966-2002, apresentando-os em categorias e subcategorias investigadas. O terceiro é constituído por um estudo documental qualitativo sobre uma amostra de pesquisas-ação, designadas por pesquisas-ação colaborativas. Procuramos dar visibilidade aos processos empreendidos em tais pesquisas: Como se organizaram? Como os processos foram conduzidos? Que estratégias foram utilizadas pelos pesquisadores para estimular o professor a refletir e a investigar suas práticas? Como aconteceu o processo de mudança? No que os professores mudaram? Que problemas enfrentaram? Que procedimentos de análise e coleta de dados utilizaram? Na quarta sessão, traçamos nossas considerações finais. Nela procuramos relacionar as práticas empreendidas nas teses e dissertações estudadas (categorias empíricas: focos das pesquisas; espaço de concretização das pesquisas; organização processual das pesquisas; repercussão do processo; problemas enfrentados; e recursos metodológicos utilizados) e as teorias sobre pesquisa-ação. / The main object of this research aimed for giving visibility to the Brazilian production in action-research / action-inquiry, focusing overall on collaborative action-research. These research\'s conceptions stimulates the approach among teachers and researchers, by collaborating on investigative proceedings developed with, for e by teachers on school practices. In most cases, those researches were developed in schools. This study was developed in four sections: The first one is formed by a bibliographic study that aimed to indicate the theoreticians that have influenced this modality of research in Brazil. In order to achieve that some authors were taken: Saul, Freire, Thiollent, Barbier, Costa, André, Nóvoa, Geraldi, Fiorentini, Pereira, Stenhouse, Elliott, Carr, Kemmis and Zeichner. On the second part we have mapped dissertations and thesis on this kind of action-research, produced in Post Graduation Programs of Education in Brazil, between 1966-2002, presenting them in categories and subcategories investigated. The third one is formed by a qualitative documental study about a sample of actionresearches, designed by collaborative action-researches. It aimed to give visibility to process undertaken in those researches. How did they get organized? How the process were lead? Which strategies were used by the researches to stimulate teachers to reflect and investigate their practices? How happened the changing process? How have the teachers changed? What kind of problems they faced? Which proceedings of analysis and collecting of data did they use? On the fourth section, supported by the first and third parts, we related the practices undertaken in thesis and dissertations studied (empirical categories: researches\'s focus; space of materialization of the researches; procedural organization of the researches; repercussion of the process; problems faced and; methodological resources used) and the theories about action-research.