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Some Initiatives in Calculus TeachingAbramovitz, Buma, Berezina, Miryam, Berman, Abraham, Shvartsman, Ludmila 10 April 2012 (has links)
In our experience of teaching Calculus to engineering undergraduates we have had to grapple
with many different problems. A major hurdle has been students’ inability to appreciate the
importance of the theory. In their view the theoretical part of mathematics is separate from the
computing part. In general, students also believe that they can pass their exams even though they
do not have a real understanding of the theory behind the problems they are required to solve. In
an effort to surmount these difficulties we tried to find ways to make students better understand
the theoretical part of Calculus. This paper describes our experience of teaching Calculus. It
reports on the continuation of our previous research.
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Additive manufacturing and radio frequency filters : A case study on 3D-printing processes, postprocessing and silver coating methodsGarcía-Verdugo Zuil, Ana, Herrero Martín, Amanda January 2020 (has links)
Additive manufacturing (AM) is an attractive way to shorten development time, reduce product weight and allow the manufacturing of more complex products than by conventional manufacturing processes. The problem arises when the previous traditional manufacturing requirements need to be fulfilled by AM as well as the volume production capability. This investigation is done together with Ericsson to evaluate the possibilities of the different AM technologies, post-processing methods and silver coating processes to guarantee the specifications of radiofrequency (RF) filters. Here, minimal RF signal insertion losses are targeted. Since insertion losses are dependent on surface roughness, surface smoothness is sought as well. Ericsson simulation software uses correction factors to account for surface roughness, however there are some inconsistencies between the simulated and actual surface roughness that is allowed in the parts. In AM parts, surface roughness is not easy to control since it depends on parameters related to feedstock, process and machine properties. Commonly, most AM components do not comply with requirements of lower surface roughness values. Therefore, parts need to be smoothened before silver plated; this step is necessary to ensure the electrical conductivity in this specific application. These finishing processes add costs to the final product and increase time to market. Firstly, a comprehensive study was carried out to better understand the landscape of AM technologies, postprocessing and silver coating methods. Secondly, the different processes are assessed with the help of selection matrices, considering the products requirements. The components to print are two RF filters with different shapes and dimensions but similar requirements. The CAD design is modified depending on each AM process and directly affects the results. Afterwards, the design of an experimental plan is carried out; the number of samples of each part comparing AM technologies, feedstock, different suppliers (3D printing and post-processing) is obtained. Due to budget and time restrictions, the parts were printed using Multi Jet Fusion and Selective Laser Melting processes. After printing, tolerances and surface roughness were measured. This thesis results in the selection of suitable AM technologies and post-processing methods for RF filters. For MJF printed cavities at 0˚, 30˚ and 90˚ orientation, the best results for this application are obtained at 30˚ providing a good balance between sharp detail and smooth surfaces. In the case of SLM, waveguides are printed at 0˚ and 30˚. 30˚ waveguides present lower surface roughness values than the 0˚ ones as inner support material is needed at 0˚ orientation. SLM cavities were printed at 30˚ in seek of asymmetry between faces, resulting in higher surface roughness in the downfacing face.
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Nouveaux composants optiques pixellises pour la correction visuelle : modélisation, optimisation et évaluation.Peloux, Marius 12 October 2011 (has links) (PDF)
Ce manuscrit de thèse traite de l'étude de verres ophtalmiques microstructurés et plus particulièrement pixellisés, ces derniers pouvant présenter un intérêt particulier en optique active pour la correction de la presbytie. Une étude théorique est proposée, permettant d'analyser les performances optiques d'une lentille pixellisée en termes de transport d'image et d'identifier les paramètres qui ont un impact direct sur ces performances. Après validation expérimentale des résultats obtenus, nous constatons puis expliquons l'effet sur l'observation d'une scène de l'excentrement de l'œil par rapport à la fonction de phase du verre. Nous étudions l'effet du repliement de phase inhérent aux limites des technologies de fabrication, qui vient ajouter un chromatisme axial aux défauts visuels engendrés par la pixellisation. Nous nous intéressons ensuite aux applications possibles de la pixellisation en optique passive. Nous prouvons que pour une application visée, des lentilles binaires non pixellisées, dont nous optimisons la qualité optique, conduisent à de meilleurs résultats que les lentilles pixellisées. L'impact sur l'acuité visuelle des phénomènes diffractifs parasites induits par la pixellisation est évalué au moyen d'un banc de mesure utilisant la simulation de certaines images telles qu'elles seraient vues au travers de verres ophtalmiques pixellisés. Enfin, nous menons une étude de l'aspect esthétique d'un verre pixellisé vu par un observateur externe, à partir de modèles de calcul hybrides mêlant optique géométrique et optique de Fourier.
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Selective laser melting of Al-12SiPrashanth, Konda Gokuldoss 17 July 2014 (has links) (PDF)
Selective laser melting (SLM) is a powder-based additive manufacturing technique consisting of the exact reproduction of a three dimensional computer model (generally a computer-aided design CAD file or a computer tomography CT scan) through an additive layer-by-layer strategy. Because of the high degree of freedom offered by the additive manufacturing, parts having almost any possible geometry can be produced by SLM. More specifically, with this process it is possible to build parts with extremely complex shapes and geometries that would otherwise be difficult or impossible to produce using conventional subtractive manufacturing processes. Another major advantage of SLM compared to conventional techniques is the fast cooling rate during the process. This permits the production of bulk materials with very fine microstructures and improved mechanical properties or even bulk metallic glasses. In addition, this technology gives the opportunity to produce ready-to-use parts with minimized need for post-processing (only surface polishing might be required). Recently, significant research activity has been focused on SLM processing of different metallic materials, including steels, Ti-, Ni- and Al-based alloys. However, most of the research is devoted to the parameters optimization or to feasibility studies on the production of complex structures with no detailed investigations of the structure-property correlation.
Accordingly, this thesis focuses on the production and structure-property correlation of Al-12Si samples produced by SLM from gas atomized powders. The microstructure of the as-prepared SLM samples consists of supersaturated primary Al with an extremely fine cellular structure along with the residual free Si situated at the cellular boundaries. This microstructure leads to a remarkable mechanical behavior: the yield and tensile strengths of the SLM samples are respectively four and two times higher than their cast counterparts. However, the ductility is significantly reduced compared with the cast samples. The effect of annealing at different temperatures on the microstructure and resulting mechanical properties of the SLM parts has been systematically studied by analyzing the size, morphology and distribution of the phases. In addition, the mechanical properties of the SLM samples have been modeled using micro- structural features, such as the crystallite and matrix ligament sizes. The results demonstrate that the mechanical behavior of the Al-12Si SLM samples can be tuned within a wide range of strength and ductility through the use of the proper annealing treatment.
The Al-Si alloys are generally used as pistons or cylinder liners in automotive applications. This requires good wear resistance and sufficient strength at the operating temperature, which ranges between 373 – 473 K. Accordingly, the tensile properties of the SLM samples were also tested at these temperatures. Changing the hatch style during SLM processing vary the texture in the material. Hence, samples with different hatch styles were produced and the effect of texture on their mechanical behavior was evaluated. The results show that the hatch style strongly influences both the mechanical properties and the texture of the samples; however no direct correlation was observed between texture and mechanical properties. The wear properties of the Al-12Si material was evaluated using pin-on-disc and fretting wear experiments. These experiments show that the as-prepared SLM samples exhibit better wear resistance than their cast counterparts and the SLM heat-treated samples. Finally, the corrosion investigations reveal that the SLM samples have similar corrosion behavior as the cast specimens under acidic conditions.
A major drawback for the wide application of SLM as an industrial processing route is the limited size of the products. This is a direct consequence of the limited dimensions of the available building chambers, which allow for the production of samples with volumes of about 0.02 m3. A possible way to overcome this problem would be the use of the welding processes to join the small SLM objects to form parts with no dimensional limitations. In order to verify this possibility, friction welding was employed to join Al-12Si SLM parts. The results indicate that friction welding not only successfully permits the join materials manufactured by SLM, but also helps to significantly improve their ductility.
This work clearly demonstrates that SLM can be successfully used for the production of Al-12Si parts with an overall superior performance of the mechanical and physical properties with respect to the conventional cast samples. Moreover, the mechanical properties of the SLM samples can be widely tuned in-situ by employing suitable hatch styles or ex-situ by the proper heat treatment. This might help the development of SLM for the production of innovative high-performance Al-based materials and structures with controlled properties for automotive and aerospace applications.
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PERCEPTION OF /q/ IN THE ARABIC /q/-/k/ CONTRAST BY NATIVE SPEAKERS OF AMERICAN ENGLISH: A DISCRIMINATION TASKSawadogo, Ousmane 01 August 2015 (has links)
AN ABSTRACT OF THE THESIS OF Ousmane Sawadogo, for the Master of Arts degree in Applied Linguistics and TESOL, presented on May 4, 2015, at Southern Illinois University Carbondale. TITLE: PERCEPTION OF /q/ IN THE ARABIC /q/-/k/ CONTRAST BY NATIVE SPEAKERS OF AMERICAN ENGLISH: A DISCRIMINATION TASK MAJOR PROFESSOR: Dr. Soo Jung Chang Studies on speech perception have suggested that non-native sound perception is influenced by the listener’s native language. Non-native sound contrast perception depends on a given sound’s similarity or dissimilarity to the listener’s equivalent native language sound. The Perceptual Assimilation Model (PAM) posits that it is difficult to distinguish non-native sounds when they are perceived as very similar to native sounds and are thus assimilated to a native sound category, but identification is easier when the non-native is sound is dissimilar to a native sound (Best, 1994a). The present study investigated whether native speakers of American English would display very good discrimination of /q/ in the Arabic /q/-/k/ contrast as predicted by the PAM. The Speech Learning Model (SLM) posits that non-native perception is position-sensitive and hypothesizes that the listener’s perception of non-native sounds would vary from one position to another (Flege, 1995). The current study also aimed to investigate whether the discrimination of the Arabic /q/-/k/ contrast would be position-sensitive. The current study also investigated the effect of the vocalic context on the discrimination of /q/. Participants consisted of 22 (6 male and 16 female) native speakers of American English who were students or faculty members at Southern Illinois University. Their ages ranged between 19 and over 50. The data were collected through an online AXB discrimination task survey. Target sounds were represented in 108 pseudowords so that the sounds could be contrasted in minimal pairs. The environments were word-initially followed by /i/, /u/, and /a/; word-medially, between two instances of /i/, two instances of /u/, and two instances of /a/; and word-finally, preceded by /i/, /u/, and /a/. Two pseudoword pairs were selected for each contrast. Four AXB combinations (AAB, ABB, BAA, and BBA) were generated for each of the nine contrasts, which resulted in a total of 36 stimuli. The participants were requested to click on a button to listen to the recordings of these word pairs and check the right answer. The findings were consistent with predictions made by PAM that native speakers of American English would have a very good discrimination of /q/ in the Arabic /q/-/k/ contrast. The results suggested that the uncategorized versus categorized (UC) type could also be of excellent discriminability. SLM was not totally supported because the differences were not statistically significant. However, the data indicated that some positions resulted in better discrimination scores than other positions and that certain vowels likewise resulted in better vocalic discrimination scores. Keywords: Discrimination task, non-native sound perception, Arabic /q/-/k/ contrast, position-sensitive, context-sensitive, vocalic context, UC type assimilation, Speech Leaning Model (SLM), Perceptual Assimilation Model (PAM).
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An IT Service Taxonomy for Elaborating IT Service Catalog / An IT Service Taxonomy for Elaborating IT Service CatalogRabbi, Md Forhad January 2009 (has links)
In this thesis, I, as the author, have tried to propose a methodology for establishing IT service taxonomy in order to elaborate IT service portfolio and IT service catalog. As a core part of my thesis, IT service taxonomy has been discussed to manage IT services in an efficient way in the small and medium sized enterprises The small and medium sized enterprises can use the categories and sub categories of this taxonomy to define their service catalog and portfolio. In that regards, a list of IT services has been identified from the industries and has been used to define the IT service taxonomy.
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Étude et contrôle cohérent du champ proche optique de milieux diélectriques désordonnés et de films semi-continus métal-diélectriques / Study and coherent control of the optical near field on disordered dielectric media and semi-continuous metal-dielectric filmsBondareff, Pierre 18 July 2014 (has links)
Un défi actuel dans le domaine de l'optique est de mieux comprendre les effets de champ proches optiques des systèmes et de pouvoir agir dessus. C'est dans ce contexte que j'explore tout au long de cette thèse ces notions appliquées aux milieux 3D diélectriques désordonnés et aux films désordonnés métal-diélectriques. Pour les milieux 3D, nous avons choisi une approche par un montage de microscopie de champ proche pour faire la mesure du champ proche optique. Nous avons pour cela dû faire un travail en amont sur la préparation des échantillons pour éviter les artefacts de mesure. Ces mesures ont révélés des structures intéressantes. Nous avons ensuite étudié les modes optiques sur les films métal-diélectriques et montré qu'il existe des modes étendus pour certaine valeurs de la faction surfacique de métal déposée. Nous avons quantifié leur extension par la mesure de la longueur d'interaction et mesuré des valeurs de l'ordre de la dizaine de microns, suffisant pour être contrôlé depuis le champ lointain. Ces mesures ont ouvert la voie au contrôle du front d'onde du faisceau incident dans l'objectif de la focalisation en champ proche de la lumière. Ceci a pu être réalisé grâce à l'utilisation d'un modulateur spatial de lumière pour le contrôle du front d'onde et à un signal non-linéaire de luminescence à deux photons pour la mesure du champ proche optique. Nous obtenons la focalisation en champ proche de l'énergie d'un facteur supérieur à dix. Enfin, la technique de microscopie de champ proche a pu être implémentée et couplée au contrôle de front d'onde et une première optimisation a pu être obtenue. Cela reste néanmoins un travail préliminaire. / One important challenge to address in the optical field is a better understanding of the optical near field of systems and how we can interact with them from the far-field. It is in this regard that I studied and controlled of the near field of both 3D disordered dielectric media and metal-dielectric disordered films. For 3D media, we used a near-field microscope to measure the optical field on their surface. To reach a free-artefact measure, we had to carefully prepare the sample by minimising the rugosity. In a second part, we studied optical modes on metal-dielectric films et we showed that it exists extended modes for some specific values of metal filling fraction of the sample. Extension of the modes has been quantified by measuring the interaction length and has been found in the order of 10 $\mu$m, enough to allow a far field control of the modes. These measurements opened the way for wavefront control of the incident beam in order to focus light in the near field of the sample. We use a spatial light modulator to control the incident wavefront and a non-linear signal (two photons luminescence - TPL) for the near-field measurement of the optical field. We could reach focusing of the energy by a factor more than ten. Finally, the SNOM technique has been coupled to the wavefront shaping system and we get preliminary measurements of optimisation in the near-field by this technique.
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Modelování podnikových procesů / Modeling business processesSkala, Jakub January 2008 (has links)
The diploma thesis deals with the theme of Modeling business processes with orientation to the metric process interface. The aim of the thesis is to design the architecture of metric, which enabled to construct type metrics of the process interface. Firstly, the reader is informed about the basic terms related to process modeling, process management and connection of strategy with metrics. The next part describes the architecture of metrics created, which is oriented to supporting the process management of the organization. The set of type metrics was chosen with consideration to the possibility of their placement on process interface. The set created in this manner should help to connect strategy with processes when implementing into organization. The last part of the thesis describes the practical application of knowledge obtained in the PARMA project. This project deals with the proposal and implementation of the process management into the Bureau of the Municipality of Prague 10. The thesis deals with two processes and the conclusions obtained in the theoretic part of the thesis are applied herein.
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Political Ideas and Behaviour of Armed Groups : A comparative analysis of armed groups’ ideology and repertoires of sexual violence during the conflict in Darfur 2003-2006Altebo, Petra January 2017 (has links)
The purpose of this thesis is to study under what conditions armed groups practice different repertoires of sexual violence, by studying ideology’s influence on behaviour. This will be explored through a structured focused comparison of three armed groups active in the conflict in Darfur 2003-2006, the Janjaweed, Sudan’s Liberation Army/Movement and the Justice and Equality Movement. The theory suggest that a strong implemented ideology will lead to control over behaviour and values, hence sexual violence will be practice in line with organizational objectives and ideas, either instrumental or not practiced at all. Consequently, a weak ideological framework will lead to variation in socialization processes and an opportunistic repertoire. The findings correlate as expected by the hypothesis, while data constraints call for caution. The results suggests a broadening of the theoretical framework as well as further studies on the suggested causal mechanism, combatant socialization, to examine how, and under what circumstances, behaviours are spread as a social practice among combatants.
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Design and manufacturing of SLM printed tooling for plastic injection moldingTing, Huang, Daniel, Nordqvist January 2021 (has links)
The thesis work is to show that the use of SLM (Additive Manufacturing) compared with the traditional process to make injection molds will have advantages in design, especially in waterways. This thesis work gives seven different versions of design applied to the SLM method to analyze and compare them in Solidworks® and Moldflow® to figure out what design is suitable for the SLM method. Through analysis of different versions, the finding of this thesis work is that the conformal waterway of design and lighter but stead structure in the SLM method causes the SLM molds' cooling performance to be almost 15% better than the conventional way and shorten the production time by 18% per product. Based on the advantages of the SLM method in cooling system design and structure optimization, the company can use the SLM method in the production process to improve economic and environmental benefits.
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