• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 4
  • 3
  • Tagged with
  • 9
  • 9
  • 4
  • 4
  • 4
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The impact of tool performance on micromachining capability

Zdebski, Daniel January 2012 (has links)
Micro-milling represents a versatile and fast manufacturing process suitable for production of fully 3D micro-components. Such components are demanded for a vast number of industrial applications including safety systems, environmental sensors, personalized medical devices or micro-lenses and mirrors. The ability of micro-milling to process a wide range of materials makes it one of the best candidates to take a leading position in micromanufacturing. However, so far it does not seem to happen. By discussion with various industrialists, low predictability of micro-milling process was identified as the major limiting factor. This is mainly because of strong effects of the tool tolerances and process uncertainties on machining performance. Although, these issues are well known, they are not reflected by the current modelling methods used in micro-milling. Therefore, the research presented in this thesis mainly concentrates on development of a method allowing a prediction of the tool life in manner of tool breakage probability. Another important criterion which must be fulfilled is the method applicability to industrial applications. This means that the method must give sufficiently accurate prediction in reasonable time with minimum effort and interactions with day-to-day manufacturing process. The criteria listed above led to development of a new method based on analytically/numerical modelling techniques combined with an analysis of real tool variations and process uncertainty. Although, the method is presented in a relatively basic form, without considering some of the important factors, it shows high potential for industrial applications. Possibility of further implementation of additional factors is also discussed in this thesis. Additionally, some of the modelling techniques presented in this thesis are assumed to be suitable for application during designing of micro end-mills. Therefore, in the last part of this thesis is presented a systematic methodology for designing of micro end-mills. This method is based on knowledge and experience gained during this research.
2

Bioinformatique et épissage dans les pathologies humaines / Bioinformatics and splicing in human diseases

Desmet, François-Olivier 07 December 2010 (has links)
Découvert en 1977, l'épissage est une étape de maturation post-transcriptionnelle consistant à rabouter les exons et éliminer les introns d'un ARN pré-messager. Pour que l'épissage soit correctement pris en charge par l'épisome et ses protéines auxiliaires, différents signaux sont présents le long de la séquence de l'ARN pré-messager. Il est maintenant reconnu que près de la moitié des mutations pathogènes chez l'homme impactent l'épissage, aboutissant à un dysfonctionnement du gène. Il est ainsi indispensable pour les biologistes d'être capables de détecter ces signaux sur une séquence génomique.Cette thèse a donc pour but de concevoir de nouveaux algorithmes permettant d'apporter la puissance de calcul des ordinateurs au service de la biologie de l'épissage. La solution proposée, Human Splicing Finder (HSF), est capable de prédire les trois types de signaux d'épissage à partir d'une séquence quelconque extraite du génome humain. Nous avons évalué l'efficacité de prédiction d'HSF dans l'ensemble des situations associées à des mutations pathogènes pour lesquelles il a été démontré expérimentalement leur impact sur l'épissage et par rapport aux autres algorithmes de prédiction. Parallèlement à ces apports directs tant pour la connaissance des processus biologiques de l'épissage que pour le diagnostic, les nouvelles approches thérapeutiques génotype-spécifiques peuvent également bénéficier de ces nouveaux algorithmes. Ainsi HSF permet de mieux cibler les oligonucléotides anti-sens utilisés pour induire le saut d'exon dans la myopathie de Duchenne et les dysferlinopathies.La reconnaissance récente de l'intérêt majeur de l'épissage dans des domaines aussi variés que la recherche fondamentale, la thérapeutique et le diagnostic nécessitaient un point central d'accès aux signaux d'épissage. HSF a pour objet de remplir ce rôle, en étant régulièrement mis à jour pour intégrer de nouvelles connaissances, et est d'ores et déjà reconnu comme un outil de référence. / Discovered in 1977, splicing is a post-transcriptional maturation process that consists in link-ing exons together and removing introns from a pre-messanger RNA. For splicing to be cor-rectly undertaken by the spliceosome and its auxiliary proteins, several signals are located along the pre-messanger RNA sequence. Nearly half of pathogenous mutations in humans are now recognized to impact splicing and leading to a gene dysfunction. Therefore it is es-sential for biologists to detect those signals in any genomic sequence.Thus, the goals of this thesis were to conceive new algorithms: i) to identify splicing signals; ii) to predict the impact of mutations on these signals and iii) to give access to this information to researchers thanks to the power of bioinformatics. The proposed solution, Human Splicing Finder (HSF), is a web application able to predict all types of splicing signals hidden in any sequence extracted from the human genome. We demonstrated the prediction's efficiency of HSF for all situations associated with pathogenous mutations for which an impact on splicing has been experimentally demonstrated. Along with these direct benefits for the knowledge of biological processes for splicing and diagnosis, new genotype-specific therapeutic approaches can also benefit from these new algorithms. Thus, HSF allows to better target antisense olignucleotides used to induce exon skipping in Duchenne myopathy and dysferlinopathies.The recent recognition of the major interest of splicing in various domains such as fundamen-tal research, therapeutics and diagnosis needed a one stop shop for splicing signals. HSF has for object to fulfill this need, being regularly updated to integrate new knowledge and is already recognized as an international reference tool.
3

Barriers and Facilitators to Infant Feeding among Low-Income African American Women

Barbosa, Cecilia E 01 January 2014 (has links)
Objective The purpose of the mixed methods study was to compare barriers and facilitators encountered by low-income African American women who engaged in different infant feeding practices. Methods Using the positive deviance approach and modified Integrated Model as theoretical frameworks, the research began with a qualitative study that informed a survey examining intention, skills, and environmental factors differentiating women’s infant feeding practices. Results Twenty-eight and 190 low-income African American adult women participated in focus groups or interviews and a survey, respectively. In the qualitative study, positive deviants, who breastfed for at least four months, seemed to have stronger breastfeeding intentions, self-efficacy and breastfeeding support than other women. In the final multinomial multiple logistic regression, for a one unit increase in the PBC scale of the revised Breastfeeding Attrition Prediction Tool, there was a 50% (OR 1.5[1.3-1.7]) and an 18% (OR 1.18 [1.03-1.3]) increase in the odds of breastfeeding at least three months (positive deviance) compared to only formula-feeding and breastfeeding for less than three months, respectively. Women who did not smoke postpartum were 4.3 [1.5-12.3] and 5.6 [2.1-15.1] times as likely to be positive deviants; women who had C-sections were 3.6 [1.3-9.6] and 2.9 [1.0-7.8] times as likely to be positive deviants compared to only formula-feeding and breastfeeding for less than three months, respectively. Women who ranked WIC full breastfeeding packages as most valuable were 14.9 [4.8-45.5] and 16.1 [5.3-50.0] times as likely to be positive deviants compared to only formula-feeding and breastfeeding for less than three months, respectively. Discussion High breastfeeding self-efficacy was associated with positive deviance, although the qualitative study findings suggested that general self-efficacy may also influence breastfeeding success. The likelihood of not smoking being associated with longer duration of breastfeeding is consistent with previous research. The C-section results may reflect a longer length of hospital stay leading to increased mastery of breastfeeding prior to discharge. Analysis of participants’ valuation of WIC infant feeding incentives led to the suggestion that WIC incentives be re-examined. Further exploration of these findings and subsequent interventions may lead to improved breastfeeding rates among low-income African American women.
4

Towards quantifying the quality of tranquil areas with reference to the National Planning Policy Framework.

Watts, Gregory R., Pheasant, Robert J. 2013 May 1924 (has links)
yes / The UK has recently recognized the importance of tranquil spaces in the National Planning Policy Framework, NPPF. This paper reports on applying the tranquillity rating prediction tool, TRAPT for predicting the perceived tranquillity of a place and using this tool to classify the levels of tranquillity in existing areas. The tool combines soundscape and landscape measures to produce a tranquillity rating on a 0-10 rating scales. For these purposes noise maps, spot noise level measurements, photographic surveys were used to predict tranquillity levels in 8 parks and open spaces in or near the city of Bradford in West Yorkshire in the UK. In addition interviews were conducted with visitors to validate these predictions. It was found that there was a reasonably close relationship between predicted and average assessments given by park visitors which confirmed the usefulness of the tranquillity rating prediction tool for planning and conservation purposes.
5

Tranquillity and soundscapes in urban green spaces - predicted and actual assessments from a questionnaire survey

Watts, Gregory R., Miah, Abdul H.S., Pheasant, Robert J. January 2013 (has links)
Yes / A pilot study had previously demonstrated the utility of a tranquillity prediction tool TRAPT for use in 3 green open spaces in a densely populated area. This allows the calculation of perceived levels of tranquillity in open spaces. The current study expands the range of sites to 8 and importantly considers the views of visitors to these spaces. In total 252 face to face interviews were conducted in these spaces. An important aim of the survey was to determine the extent to which reported tranquillity obtained from the questionnaire survey could be predicted by a previously developed prediction tool TRAPT. A further aim was to determine what additional factors may need to be considered in addition to the purely physical descriptors in TRAPT. The questions included the sounds and sights that were noticed, factors affecting tranquillity as well as questions relating to the benefits of visiting these areas. Predictions were considered satisfactory and could be further improved by taking account of issues surrounding personal safety. Examining the trends in these data it was also shown that the percentage of people feeling more relaxed after visiting the spaces was closely related to overall assessments of perceived tranquillity. Further trends and their implications are presented and discussed in the paper. / Made available in full text March 2014 at the end of the publisher's embargo period.
6

Factors affecting tranquillity in the countryside.

Watts, Gregory R., Pheasant, Robert J. 24 May 2013 (has links)
Yes / Previous work on elucidating the tranquillity of various environments has largely focussed on prediction and validation in urban environments. The setting for the latest phase of research was an English country park and surrounding moors on the urban fringe located 8 miles west of Bradford. Within the area selected there were a number of environments and man-made features and sounds that were thought to significantly affect tranquillity and which were not covered in earlier studies. The experiment extended over a number of months and utilised a jury technique for evaluation involving leading small groups of walkers to different locations in quasi-random order. At each location participants were asked to complete a short questionnaire and measurements of the physical soundscape and landscape images were used to interpret the results and give insights into the importance of the various factors affecting tranquillity. Such data will be useful for effective environmental management and conservation in the countryside.
7

Développement et validation d’outils Monte-Carlo pour la prédiction des basculements logiques induits par les radiations dans les mémoires Sram très largement submicroniques / Development and validation of Monte-Carlo tools for the prediction of soft errors induced by radiations in deep submicron Sram memories

Weulersse, Cécile 06 December 2011 (has links)
Les particules de l'environnement radiatif naturel sont responsables de dysfonctionnements dans les systèmes électroniques. Dans le cas d'applications critiques nécessitant une très haute fiabilité, il est primordial de répondre aux impératifs de sûreté de fonctionnement. Pour s'en assurer et, le cas échéant, dimensionner les protections de manière adéquate, il est nécessaire de disposer d'outils permettant d'évaluer la sensibilité de l'électronique vis-à-vis de ces perturbations.L'objectif de ce travail est le développement d'outils à destination des ingénieurs pour la prédiction des aléas logiques induits par les radiations dans les mémoires SRAM. Dans un premier temps, des bases de données de réactions nucléaires sont construites à l'aide du code de simulation Geant4. Ces bases de données sont ensuite utilisées par un outil Monte-Carlo dont les prédictions sont comparées avec des résultats d'irradiations que nous avons effectuées sur des mémoires SRAM en technologie 90 et 65 nm. Enfin, des critères simplifiés reposant sur une amélioration de la méthode SIMPA nous permettent de proposer un outil d'ingénieur pour la prédiction de la sensibilité aux protons ou aux neutrons à partir des données expérimentales ions lourds. Cette méthode est validée sur des technologies de SRAM très largement submicroniques et permet l'estimation des évènements multiples, une problématique croissante pour les applications spatiales, avioniques et terrestres. / Particles from natural radiation environment can cause malfunctions in electronic systems. In the case of critical applications involving a very high reliability, it is crucial to fulfill the requirements of dependability. To ensure this and, if necessary, to adequately design mitigations, it is important to get tools for the sensitivity assessment of electronics towards radiations.The purpose of this work is the development of prediction tools for radiation-induced soft errors, which are primarily intended for end users. In a first step, the nuclear reaction databases were built using the Geant4 toolkit. These databases were then used by a pre-existing Monte-Carlo tool which predictions were compared with experimental results performed on 90 and 65 nm SRAM devices. Finally, simplified criteria enabled us to propose an engineering tool for the prediction of the proton or neutron sensitivity from heavy ion data. This method was validated on deep submicron devices and allows the user to estimate multiple events, which are a crucial issue in space, avionic and ground applications.
8

The effects of “greening” urban areas on the perceptions of tranquillity

Watts, Gregory R. 26 May 2017 (has links)
Yes / Tranquil environments can provide relief from stresses of everyday of life and can be considered restorative environments. This paper considers the effects of “greening” urban environments to enhance tranquillity and ultimately well-being and health benefits. A number of studies have been conducted at the Bradford Centre for Sustainable Environments at the University of Bradford which have examined the effects of natural features on ratings of tranquillity. These include quantifying the effects of the percentage of natural and contextual features and soundscape quality on rated tranquillity. Recently the resulting prediction equation TRAPT (Tranquillity Rating Prediction Tool) has been used to examine a number of scenarios including city parks and squares, country parks and moorland areas and validated using tranquillity ratings made by visitors to these green spaces and their reported levels of relaxation. In this paper TRAPT is used for predicting tranquillity in city squares of different sizes, to examine rated tranquillity behind natural (green) and manufactured noise barriers and to predict changes in urban streets of introducing avenues of trees, hedges and grass verges. Using such scenarios this paper demonstrates how the application of TRAPT can enable changes in tranquillity to be estimated. This can provide planners, environmentalists, civic leaders and concerned citizens with a further tool to guide improvements in the urban environment by “greening” measures and noise reduction of various kinds and to help counter threats such as over development, tree removal or traffic densification that might threaten existing benefits. / Bradford Centre for Sustainable Environments in the Faculty of Engineering and Informatics at the University of Bradford.
9

Modélisation des écoulements à surface libre de fluides non-newtoniens / Free surface modeling of non-newtonian fluid flows

Schaer, Nicolas 27 September 2018 (has links)
L’objectif de cette thèse est de développer un modèle numérique 3D afin d’étudier le phénomène de laves torrentielles ; écoulements visqueux fortement chargés en matière solide, surgissant en montagne lors d’orages violents. Aujourd’hui, la prévision des zones de vulnérabilité s’appuie sur des outils de calcul 0D, 1D ou 2D. Or ces outils ne peuvent représenter pleinement le comportement à surface libre des écoulements du fait de nombreuses approximations et hypothèses. Ainsi cette thèse met en œuvre un code numérique 3D pour étudier ces écoulements. Ce travail aboutit à la construction d’un modèle 3D à partir de données réelles de terrain. Plusieurs scénarios ont été étudiés et comparés à des résultats issus d’un modèle 2D. Les résultats mettent en évidence les apports non négligeables de la modélisation 3D : zones d’étalement et de dépôt, phénomènes d’encombrement, modélisation fine des écoulements dans les zones chenalisées. Préalablement, le modèle 3D a été validé en comparant les résultats numériques à des données expérimentales issues de la littérature, pour des typologies d’écoulement représentatives de celles observées sur des sites grandeur nature. / The objective of this thesis is to develop a 3D numerical model to assess debris flow. These viscous flows, heavily loaded with solid matter, form when heavy rain occurs in mountains. Today, forecasts of potentially impacted areas are based on 0D, 1D and 2D numerical tools. However, these tools cannot fully represent the free surface behaviour of debris flows due to the approximations and assumptions on which they are based. Thus, this work utilises a 3D numerical code to study this phenomenon. A specific model is built with real field data. Several flow scenarios are studied and compared with a 2D numerical model. The results highlight the significant benefits of a 3D approach by providing information on the fine representation of flow dynamics over the catchment area. The model also predicts the impact of debris flow (overflowing on a road bridge) and the zones of deposition and spreading. It highlights possible congestion phenomena and reproduces flows in the channels by fully accounting for parietal friction, capabilities not provided by 2D models. Prior to this application, the 3D model was evaluated with five sets of experimental data to validate its ability to represent viscoplastic flows. Different types of flows are studied and are representative of those observed on real sites when debris flow occur.

Page generated in 0.083 seconds