The Moment Recursion (MR) models are a class of models for tactical planning of job shops or other processing networks. The MR model can be used to determine or approximate the first two moments of production quantities and queue lengths at each work station of a job shop. Knowledge of these two moments is sufficient to carry out a variety of performance evaluation, optimization and decision-support applications. This paper presents a literature survey of the Moment-Recursion models. Limitations in the existing research and possible research opportunities are also discussed. Based on the research opportunities discussed, we are in the process of building a model that attempts to fill these research gaps. / Singapore-MIT Alliance (SMA)

Les travaux présentés dans cette thèse s’inscrivent dans le contexte de l’identification de l’influence des paramètres de coupe et géométries d’outil sur l’usinabilité de l’alliage de titane Ti-6Al-4V sous deux états cristallographiques : alpha\beta et beta et s’insèrent dans le projet TiMaS, en partenariat avec Airbus et Figeac Aéro. La première partie consiste donc en une identification des différents critères d’usinabilité considérés dans la bibliographie pour l’usinage des titanes et la modélisation des actions thermomécaniques régissant la coupe. Dans une deuxième partie, l’usinabilité des deux matériaux a été étudiée pour deux outils coupants, utilisés par les industriels, constituant ainsi nos deux couples outil matière. Aussi, suivant la démarche du Couple Outil-Matière (COM) un espace de fonctionnement des conditions de coupe a été défini pour les deux couples considérés, afin de déterminer les paramètres de coupe garantissant une amélioration de la productivité. Les efforts de coupe, ainsi que la durée de vie des outils ont de ce fait été sélectionnés comme critère d’usinabilité. Egalement, l’observation de la morphologie des copeaux et de leur état de déformation a permis de voir les singularités de comportement existantes entre les deux microstructures. Ces singularités ayant un impact sur la géométrie même du copeau et les actions thermomécaniques exercées par ce dernier sur les outils coupants, dans la troisième partie, des essais de coupe orthogonale (pour les deux matériaux) ont été effectués afin d’évaluer l’impact des géométries d’outil, des conditions de coupe et de la microstructure du matériau sur la thermomécanique de la coupe et les longueurs de contact entre la face de coupe des outils coupant et le copeau. La visualisation de l’écoulement du copeau par caméras rapides a permis de constater une certaine variabilité des longueurs de contact, influencée en partie par les paramètres de coupe et majoritairement par l’état cristallographique du matériau. L’analyse EDX des faces de coupe des outils coupant a montré que cette variabilité a une influence marquée sur l’usure en diffusion des plaquettes. Enfin, dans une dernière partie, un dernier critère d’usinabilité est étudié, reposant sur l’analyse des contraintes résiduelles générées par la coupe en surface de la pièce usinée. En se basant sur les essais de coupe orthogonale réalisés dans la partie précédente, une modélisation numérique basée sur un couplage thermomécanique faible a été développée afin de déterminer l’effet des conditions de coupe et des géométries d’outil sur les actions thermomécaniques et donc la génération de contraintes résiduelles, pour le cas du matériau à structure cristallographique bimodale. Les résultats de la modélisation ont ensuite étés comparés à des mesures de diffractométrie à rayons X effectués sur les pièces. / The work presented in this thesis aims to identify the influence of cutting conditions and tool geometries on Ti-6Al-4V alloy’s machinability under two microstructural states: alpha\beta and beta. This thesis takes part into the TiMaS project involving collaboration with Airbus and Figeac Aero. In a first part, we have identified machinability criteria usually considered for titanium alloys. Also, models describing thermomechanical actions occurring during cutting process are explored. In a second part, the two materials’ machinability has been studied for two cutting tools used by the industrials. Following the Tool Material Pair method, an operating space has been defined for the considered pairs. Then, cutting conditions leading to an increase of productivity have been obtained. Cutting forces as well as tool lives have been chosen has machinability criteria. Moreover, observations of chips and their states of deformation highlighted some behavior singularities between the two materials. These singularities have an impact on chip geometries and thermomechanical actions applied on cutting tools. Thus, in a third part, orthogonal cutting tests have been done in order to evaluate the effect of cutting conditions, tool geometries and microstructural state of the work material on thermomechanical actions of the cutting process and on tool chip contact lengths. Observations made on the chip flowing, with high speed cameras, have shown a variability of these contacts, mostly due to the microstructural state of the material. EDX measurements made on tools’ rake face allowed linking these variabilities to diffusion wear. In the last part, residual stresses induced by cutting process on the finished surface has been taken as the last machinability criterion for this study. Using orthogonal cutting test datas from the previous part, a numerical modeling using a low thermomechanical coupling has been carried out in order to understand cutting condition and geometry effects on residual stress generation. Modeling results have been confronted to residual stress measurements made with X-ray diffraction method on finished surface.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-05-02T14:06:25Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Serpa EDUMATEC CD (1).pdf: 1958141 bytes, checksum: c34df3e6d1df28315e381a223647d7fe (MD5) / Made available in DSpace on 2017-05-02T14:06:26Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Serpa EDUMATEC CD (1).pdf: 1958141 bytes, checksum: c34df3e6d1df28315e381a223647d7fe (MD5) Previous issue date: 2016-03-09 / O objetivo desta dissertação foi investigar o ensino da medição de comprimentos para estudantes da disciplina Metrologia em um curso profissionalizante do Programa Nacional de Ensino Tecnológico – PRONATEC, sob responsabilidade do Ministério da Educação – MEC (BRASIL, 2011). Tais alunos estão, simultaneamente, matriculados em uma escola pública do ensino médio regular da Região Metropolitana do Recife. Nessas escolas, como se sabe, eles estudam as disciplinas Matemática e Física. Além disso, escolhemos focalizar nosso trabalho no ensino do uso do paquímetro, dispositivo amplamente utilizado nas medições de comprimento, no âmbito da indústria, dos serviços profissionais e nas ciências. O quadro teórico adotado é a transposição didática (Chevallard, 1991). A medição de comprimento requer a consideração de vários conceitos matemáticos, entre os quais o de número racional (a medida de comprimento) bem como o da incerteza do resultado dessa medição (o “erro de medida”). Optamos por investigar materiais didáticos disponíveis para os estudantes do citado curso, em particular duas apostilas de Metrologia e as coleções de Matemática de Física. Esses materiais foram analisados do ponto de vista de se constituírem um dos elementos que cumprem o papel de meios da transposição didática dos saberes em jogo. A análise dos dados obtidos revelou vários pontos em que o saber estabelecido no campo das grandezas e da medição de grandezas é abordado de modo inadequado, nos materiais didáticos examinados. Isso conduz à hipótese de que fica comprometida nesses materiais uma transposição didática que se apresente como um instrumento eficaz de aprendizagem dos estudantes. / The aim of this work was to investigate the teaching of length measurement for students Metrology course in a course of the National Technological Education Program - PRONATEC, under the Ministry of Education - MEC (BRAZIL, 2011). Such students are simultaneously enrolled in a public school in regular high school in the Metropolitan Region of Recife. In these schools, as we know, they study subjects Mathematics and Physics. In addition, we chose to focus our work in teaching the use of vernier caliper, widely used device for length measurements in the industry, professional services and science. The theoretical framework is the didactic transposition (Chevallard, 1991). The length measurement requires consideration of various mathematical concepts, including the rational number (gauge length) as well as the uncertainty of the result of measurement (the "measurement error"). We chose to investigate teaching materials available to students of that course, in particular two booklets Metrology and collections of Mathematical Physics. These materials were analyzed from the point of view of constituting one of the elements that play the role of means of didactic transposition of knowledge into play. The data analysis revealed several points where the established knowledge in the field of quantities and measured variables is addressed improperly in teaching materials examined. This leads to the hypothesis that is compromised in these materials a didactic transposition that is presented as an effective learning tool for students.

This focuses on hydrological transport in shallow catchments with topography-driven flow paths. The thesis gives new insight to kinematic pathway models for estimation of tracer discharge at the catchment outlet. A semi-analytical methodology is presented for transient travel time and age distributions referred to as "kinematic pathway approach“(KPA) that accounts for dispersion at two levels of morphological and macro-dispersion. Macro-dispersion and morphological dispersion components are reflected in KPA by assuming an effective Péclet number and topographically driven pathway length distributions, respectively. The kinematic measure of the transport, defined as a characteristic velocity of water flow through the catchment is obtained from the overall water balance in the catchment. To include transformation process in its simplest form of linear decay/degradation a framework is presented that solves one-dimensional reactive transport with numerically simulated travel times as the independent variable. The proposed KPA and coupled transport framework for quantifying tracer discharge at the shallow catchment outlet are applied to two selected catchments in Sweden. KPA is applied to modeling of a 23-year long chloride data series for the Kringlan catchment whereas the implantation of the framework for quantifying natural attenuation is illustrated for the Forsmark catchment. Numerical simulations of Forsmark catchment advective travel times are obtained by means of particle tracking using the fully-integrated flow model MIKE SHE. The KPA is found to provide reasonable estimates of tracer discharge distribution when considering the transport controlled by hillslope processes associated with short topographically driven flow paths to adjacent discharge zones, e.g. rivers and lakes. Simulated natural attenuation for Forsmark is also estimated well provided that the pathway length distribution is skewed toward short pathway lengths. This fact is indicative of the controlling impact of topography on flow path length and travel time distributions in shallow catchments. Our work has shown that the pathway (Lagrangian) methodologies are promising as predictive tools for hydrological transport. / <p>QC 20170928</p>

Longest prefix matching is a well-studied problem in the context of IP-packet forwarding, an area of computational specialization where high performance with low memory impact is of the essence. Numerous specialized data structures exist for longest prefix matching in this setting, among them is Waldvogels binary search on lengths, WBSL for short. This data structure has previously been augmented with a Bloom filter to improve its performance, resulting in a new data structure: WBSL-BF. This study concerns the potential performance improvement of adding length-awareness to WBSL-BF. Performance of the augmented data structure is evaluated by recording the number of hash table accesses performed to carry out a series of queries, along with false positive rates for the Bloom filters. A test program is created to run multiple series of queries with different test configurations. The data structure is evaluated using two datasets containing prefixes from routing information base snapshots from real route collectors. The two datasets contain roughly 80000 and 900000 prefixes respectively. The results indicate that on the given datasets, augmenting the Bloom filter with length-awareness can reduce the number of hash table accesses when performing longest prefix matching by up to 44% in a best case scenario without increasing memory usage. However, the performance gain is limited in other scenarios, since the optimally configured standard Bloom filter leaves little to improve upon when applied to Waldvogels binary search on lengths.

No description available.

The painting Seated lady writing has undergone a technical investigation where its material characteristics were unveiled using non-invasive analytical techniques employing different wavelengths of the spectrum. The panel was analyzed from a material and a visual culture perspective. The thesis aimed to answer what the panel has undergone through time, how its materiality relate to its function, and where and when it was created. In addition, the aim was to investigate the objects portrayed and their value within the artwork’s historical cultural context. The panel show diverse damages that might relate to insect activity, carving with a sharp tool in the face area, stabilization methods evident from remnants of a removed cradling and a possible dimensional reduction. Preparatory features including both free hand underdrawing for minor details, and a tracing technique used for the initial rendering of the female figure and some of the textiles were identified. A blend of meticulously rendered detailing with areas of lesser quality in terms of execution together with the use of common pigments, point to an overall aim of producing art in anefficient way. Later interventions are evident such as the turquoise overpaint on the dress covering the original authentic violet or burgundy color. Visible in X-ray, a dense element covering the bust may be interpreted as a painted thin fabric. The lack of the superficial viscous modelling layers reduce the face of its plasticity and many colors have altered and darkened. The setting and the woman’s fashion indicates an early Dutch 16th century courtly aesthetic. The objects in the rich interior alludes to religious symbolism referring to the Magdalene. The paintings attribution to the Master of the Female Half-Lengths was made in the early 20th century according to the panel’s stereotypical motif, despite the stylistic differences of the figure types. The panel differs from the other attributed panels in thesetting, where the woman seems contemplating in front of a diary, whereas the other women areportrayed writing, playing music or reading. This master has been regarded as synonymous with a workshop production, painting for the blooming 16th century art market in Flemish cities such as Antwerp. This thesis proposes that the paintings ought to be understood in the context of a genre The Female Half-Lengths, as opposed to adhering to one and the same attributed master.

No description available.

No description available.

La phylogénie moléculaire fournit un outil complémentaire aux études paléontologiques et géologiques en permettant la construction des relations phylogénétiques entre espèces ainsi que l’estimation du temps de leur divergence. Cependant lorsqu’un arbre phylogénétique est inféré, les chercheurs se focalisent surtout sur la topologie, c'est-à-dire l’ordre de branchement relatif des différents nœuds. Les longueurs des branches de cette phylogénie sont souvent considérées comme des sous-produits, des paramètres de nuisances apportant peu d’information. Elles constituent cependant l’information primaire pour réaliser des datations moléculaires. Or la saturation, la présence de substitutions multiples à une même position, est un artefact qui conduit à une sous-estimation systématique des longueurs de branche. Nous avons décidé d’estimer l‘influence de la saturation et son impact sur l’estimation de l’âge de divergence. Nous avons choisi d’étudier le génome mitochondrial des mammifères qui est supposé avoir un niveau élevé de saturation et qui est disponible pour de nombreuses espèces. De plus, les relations phylogénétiques des mammifères sont connues, ce qui nous a permis de fixer la topologie, contrôlant ainsi un des paramètres influant la longueur des branches. Nous avons utilisé principalement deux méthodes pour améliorer la détection des substitutions multiples : (i) l’augmentation du nombre d’espèces afin de briser les plus longues branches de l’arbre et (ii) des modèles d’évolution des séquences plus ou moins réalistes. Les résultats montrèrent que la sous-estimation des longueurs de branche était très importante (jusqu'à un facteur de 3) et que l’utilisation d'un grand nombre d’espèces est un facteur qui influence beaucoup plus la détection de substitutions multiples que l’amélioration des modèles d’évolutions de séquences. Cela suggère que même les modèles d’évolution les plus complexes disponibles actuellement, (exemple: modèle CAT+Covarion, qui prend en compte l’hétérogénéité des processus de substitution entre positions et des vitesses d’évolution au cours du temps) sont encore loin de capter toute la complexité des processus biologiques. Malgré l’importance de la sous-estimation des longueurs de branche, l’impact sur les datations est apparu être relativement faible, car la sous-estimation est plus ou moins homothétique. Cela est particulièrement vrai pour les modèles d’évolution. Cependant, comme les substitutions multiples sont le plus efficacement détectées en brisant les branches en fragments les plus courts possibles via l’ajout d’espèces, se pose le problème du biais dans l’échantillonnage taxonomique, biais dû à l‘extinction pendant l’histoire de la vie sur terre. Comme ce biais entraine une sous-estimation non-homothétique, nous considérons qu’il est indispensable d’améliorer les modèles d’évolution des séquences et proposons que le protocole élaboré dans ce travail permettra d’évaluer leur efficacité vis-à-vis de la saturation. / Molecular phylogeny provides an additional tool complementary to paleontological and geological studies, allowing the reconstruction of phylogenetic relationships between species and the estimate of their divergence time. Researchers are mainly focusing on the topology of a phylogenetic tree; i.e. the relative connection between different nodes. Whereas, the branch lengths of this phylogeny are often considered as secondary, i.e. as additional parameters containing little information. However, the branch lengths are the primary information for molecular dating. Importantly, saturation, the presence of multiple substitutions at the same position, is an artifact that leads to an underestimation of the branch length. We are therefore interested in estimating the magnitude of this phenomenon and its impact on divergence time. We chose to study the mammalian mitochondrial genome, which is available for many species and displays a high level of saturation. Furthermore, the phylogenetic relationships of mammalians are known, thus allowing us to fix the topology, thus eliminating one of the parameters influencing the branch lengths. We used two main approaches to improve the detection of multiple substitutions: (i) an increase in the number of species breaks the longest branches of the tree, (ii) more realistic models of sequence evolution. The results demonstrate that there is a very pronounced underestimation of branch lengths (up to a factor of 3). Furthermore, the use of a large number of species is the factor that influences most the detection of multiple substitutions, not the improvement of the model of sequence evolution. This suggests that even the most complex evolutionary models currently available, like the CAT+ Covarion model, which takes into account the heterogeneity of the substitution process between sites and the rates of evolution over time, are still far from taking the entire complexity of biological processes into account. Despite the important underestimation of branch lengths, the impact on dating appeared to be relatively limited, because the underestimation is more or less homothetic. This is obviously true for the complex evolutionary models. Since multiple substitutions are most effectively detected when breaking the long internal branches via the addition of species. This raises the problem of bias in the taxonomic sampling, due to the impact of extinction on the history of life on earth. Because this kind of bias leads to a non-homothetic underestimation, we consider it essential to improve models of sequence evolution and suggest that the protocol developed in this work will allow to evaluate their effectiveness towards saturation.