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  • 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.
141

EFFECT OF EFFICIENCY OF SULFUR VULCANIZATION ON PROPERTIES OF GUM AND BLACK-FILLED NATURAL RUBBER VULCANIZATES

Boonkerd, Kanoktip 17 May 2006 (has links)
No description available.
142

Synthesis of Hybrid Latexes and Polymerization Kinetics of Functional Latexes

Bas, Serkan 03 September 2009 (has links)
No description available.
143

Fabrication of Alumina Membranes From Uv Resin– Alumina Particle Slurries

Porcincula, Dominique Henry 01 December 2023 (has links) (PDF)
Ceramics membranes are made in a wide variety of different techniques using a wide variety of different materials. However, many of the common techniques utilize a slurry of ceramic particles, additives, and either organic solvent or water that is shaped into a membrane, left to dry, and then sintered together. Drying is a time consuming process, often requiring several hours for the liquid medium to evaporate. Defect formation caused by development of partial pressures across the drying membrane, including cracks and warpage, also typically occurs during the drying process. To address this, slurries of ceramic particles made with a low viscosity UV-curable resin, which can cure in the span of a few seconds, eliminating the need for drying and any defects associated with drying. Slurries were made with different particle sizes and volume fractions and made into thin membranes using an Autodesk Ember 3D printer. Curing of UV resin and slurries were examined with FTIR. Pyrolytic behavior of resin was examined using isothermal TGA. Cure depth profiles were determined using the modified Beer-Lambert Law and compared against models in literature. Results showed contrasting curing behavior based on volume fraction and particle size due to differences in UV light exposure methods.
144

Effect of Induction-Heat Post-Curing on Residual Stresses in Fast-Curing Carbon Fibre Reinforced Composites

Bettelli, Mercedes Amelia January 2020 (has links)
Manufacturing induced shape distortions is a common problem for composite materials. Due to the non-isotropic nature of carbon fibre reinforced polymers (CFRP) unavoidable deformations occur during part production. During fabrication of polymer composites, the material obtains its final shape at elevated temperatures. The curing process involves a transition from the liquid state to the solid, glassy state, allowing bonding between fibres and matrix. As the material cools the mismatch in thermal expansion coefficients and cure shrinkage obtained during the matrix polymerization leads to residual stresses on the mechanical level within composite part. There is a great interest from the aircraft and automotive industries, to increase the ability to understand development of shape distortions and residual stresses during the cure, since these deformations often lead to dissatisfaction of tolerances and it is essential to predict the deformations beforehand in order to compensate time and cost.  In this context, a study of residual stresses during the curing process of thermosetting resin composites is presented. A methodology is proposed for predicting the formation and development of manufacturing- induced residual stresses. The present project reports on a comprehensive experimental study on the dependency of different short curing cycles on the build-up of residual stresses in a carbon fibre/fast-curing epoxy system and evaluate of post-curing methods through induction heating and oven post-curing with unidirectional [904] and unsymmetrical [9020] laminates. It includes characterization in thermo-elastic properties and degree-of-cure of the material by Thermal bending test, thermal expansion test, mechanical tensile test and Differential Scanning Calorimetry (DSC) in non-post-cured and post-cured laminates. The results showed slight variation in the thermal properties and not effect in the mechanical properties at different cure and post-curing conditions. Analytical data by Laminate Analysis program validated the experimental thermo-elastic data with analytical simulations. In addition, it is shown improvements in the temperature distributions in the post-curing by induction heating with different experimental set-ups, however, oven post-curing showed a more systematic system, higher heat efficient a low cure temperature, with more consistent mechanisms of shape distortions and residual stresses compared to induction heating. These findings are relevant for the future development of prediction methods for process induced deformations of Fast Curing Epoxy Resins (FCER).
145

L'influence des transferts de responsabilité médicale sur les résultats de santé des patients en médecine d'urgence : une étude rétrospective

Mokhtari, Akram 09 November 2022 (has links)
Introduction: Un transfert de responsabilité entre médecins est le processus par lequel les médecins se cèdent la responsabilité clinique d'une unité de soins. Le département d'urgence est un environnement souvent surchargé dans lequel les soins doivent être administrés rapidement. Le risque de perte d'information lors d'un transfert y est très élevé. Pourtant, l'impact des transferts de responsabilité sur les résultats de santé des patients du département d'urgence demeure peu étudié. Nous avons effectué une étude de cohorte rétrospective afin de déterminer si, au sein du département d'urgence, les patients ayant subi un transfert de responsabilité médicale ont des résultats de santé plus défavorables que les patients qui n'en ont pas subi. Méthodologie: Nous avons inclus tous les patients d'âge adulte ayant été évalués par un médecin d'urgence puis admis dans un des cinq hôpitaux du CHU de Québec-Université Laval pendant l'année fiscale 2016-2017. Les données ont été extraites à partir des bases de données des soins hospitaliers et du système d'information de gestion des urgences (SIGDU). Le résultat de santé principal évalué était la mortalité. Les résultats secondaires étaient l'admission aux soins intensifs, la chirurgie et la durée de séjour hospitalière. Pour évaluer la mortalité, l'admission aux soins intensifs et le besoin de chirurgie, nous avons utilisé des modèles de régression logistique multiniveaux auxquels nous avons intégré un score de propension qui tenait compte des variables confondantes suivantes : hôpital, caractéristiques démographiques des individus, score de l'Échelle de Triage et de Gravité (ÉTG), comorbidités, délai avant évaluation par un médecin d'urgence, délai avant évaluation par un autre spécialiste, délai avant admission, taux d'occupation de l'urgence et nombre moyen de nouveaux patients par heure, orientation initiale au triage et heure du transfert de responsabilité. Pour évaluer la durée de séjour hospitalière, nous avons utilisé des modèles de régression log-linéaires multi-niveaux en tenant compte des mêmes confondants. Nous avons effectué des analyses de sensibilité excluant les patients ayant séjourné plus de 24h à l'urgence et excluant les événements ayant eu lieu plus de 72h après le début de l'hospitalisation. Résultats : Nous avons inclus 21136 visites à l'urgence et 17150 individus uniques dans l'étude. Les médianes [Q1; Q3] pour l'âge, l'index de Charlson, le délai avant de voir un médecin d'urgence et la durée de séjour à l'urgence étaient de, respectivement, 71[55; 83] années, 3[1; 4], 48 [24; 90] minutes, 20 [9,9;32,7] heures. En analyse par score de propension (RC transfert/pas de transfert [IC95%] ou GMR[IC95%]), le fait d'avoir été transféré n'était pas associé à la mortalité (1,08[0,93;1,26]), à la chirurgie (1,95[0,85,1,05]), à l'admission aux soins intensifs (1,01[0,87;1,18]) ou à la durée de séjour hospitalière (1,02[0,94;1,10]). L'abréviation GMR signifiant ratio de moyennes géométriques (Geometric means ratio). Les analyses de sensibilité et de sous-groupes n'ont pas apporté d'information supplémentaire. Conclusion: Les transferts de responsabilité entre médecins d'urgence ne semblent pas augmenter le risque d'événements indésirables graves tels que la mortalité. Des études supplémentaires sont nécessaires pour évaluer l'impact des transferts sur les événements indésirables potentiellement moins graves (p. ex. erreur d'administration de médicaments). / Introduction: A physician handoff is the process through which physicians transfer the primary responsibility of a care unit. The emergency department (ED) is a fast-paced and crowded environment where the risk of information loss between shifts is significant. Yet, the impact of handoffs between emergency physicians on patient outcomes remains understudied. We performed a retrospective cohort study in the ED to determine if handed-off patients, when compared to non-handed-off patients, were at higher risk of negative outcomes. Methods: We included every adult patient first assessed by an emergency physician and subsequently admitted to hospital in one of the five sites of the CHU de Québec-Université Laval during the fiscal year 2016-17. Data were extracted from the local hospital discharge database and the ED information system. Primary outcome was mortality. Secondary outcomes were incidences of ICU admission and surgery and hospital length of stay. We conducted multilevel multivariate regression analyses, accounting for patient and hospital clusters and adjusting for demographics, Canadian Triage and Acuity Score (CTAS), comorbidities, admitting department delay before evaluation by an emergency physician and by another specialty, emergency department crowding, initial ED orientation and handoff timing. We conducted sensitivity analyses excluding patients that had an ED length of stay > 24 hours or events that happened after 72 hours of hospitalization. Results: 21,136 ED visits and 17,150 unique individuals were included in the study. Median[Q1; Q3] age, Charlson index score, door-to-emergency-physician time and ED length of stay were 71[55; 83] years old, 3[1; 4], 48 [24; 90] minutes, 20.8[9.9; 32.7] hours, respectively. In propensity score analysis (OR handoff/no handoff [CI95%] or GMR[Cl95%]), handoff status was not associated with mortality (1.08[0.93,1.26]), surgery (0.95[0.85,1.05]), ICU admission (1.01[0.87,1.18]) or hospital length of stay (1.02[0.94-1.10]). ED occupancy rate was an independent predictor of mortality and ICU admission rate irrespectively of handoff status. Sensitivity and subgroup based analyses yielded no further information. Conclusion: Emergency physicians' handoffs do not seem to increase the risk of severe in-hospital adverse events. ED occupancy rate is an independent predictor of mortality. Further studies are needed to explore the impact of ED handoffs on adverse events of low and moderate severity.
146

High Performance Hyperbranched Polymers For Improved Processing And Mechanical Properties In Thermoset Composites

Marsh, Timothy Edward January 2009 (has links)
No description available.
147

PROCESS OPTIMIZATION OF PHOTOCURABLE POLYESTER GEL COAT AND LAMINATE

Crump, Larry Scott 11 June 2014 (has links)
No description available.
148

Selecting Best Compromises among Performance Measures during In-Mold Coating of Sheet Molding Compound Compression Molding Parts

Ko, Seunghyun 14 August 2015 (has links)
No description available.
149

Properties and Curing Kinetics of Epoxy Resins Cured by Chitosan

Balasubramani, Praveen Kumar January 2016 (has links)
No description available.
150

Disabling cure in twentieth-century America: disability, identity, literature and culture

Cheu, Johnson F. 15 August 2003 (has links)
No description available.

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