Magnetic Hysteretic Characterization of Ferromagnetic Materials with Objectives towards Non-Destructive Evaluation of Material Degradation

Structurele componenten en machineonderdelen vervaardigd uit staal worden vaak onder veeleisende omstandigheden uitgebaat. Dit kan aanleiding geven tot materiaaldegradatieprocessen zoals verbrossing en metaalvermoeiing. Mettertijd kunnen deze microstructurele processen leiden tot een graduele verslechtering van de mechanische eigenschappen, en eventueel tot scheurgroei en breuk. Om dit te vermijden is het monitoren van de materiaalintegriteit van groot belang, wat uitgevoerd kan worden met behulp van niet-destructieve evaluatietechnieken. In dit doctoraatsonderzoek bestuderen we de mogelijkheden van magnetische hysteretische karakteriseringstechnieken voor het niet-destructief monitoren van toenemende materiaaldegradatie van ferromagnetisch constructiestaal. Dergelijke aanpak is gemotiveerd door de kennis dat magnetisch hysteretisch gedrag beïnvloed is door microstructurele materiaaleigenschappen. Anders geformuleerd, de verandering in de vorm van de magnetische hysteresislussen, experimenteel waargenomen op verschillende momenten tijdens de materiaaldegradatie, reflecteert de onderliggende microstructurele veranderingen en de degradatie van de mechanische eigenschappen. Een van de onderzochte onderwerpen is de verbrossing van ferritisch staal door neutronenbestraling. Dit effect kan schadelijk zijn voor het drukvat van een nucleaire reactor. De maximum-permeabiliteit vertoont een significante dalende trend met stijgende neutronendosis en met stijgende vloeigrens, hetgeen het potentieel aangeeft van de magnetische hysteretische evaluatie van verbrossing door neutronenbestraling. Een andere topic is het continu monitoren van metaalvermoeiing aan de hand van een magnetomechanische methode. Deze methode resulteert in informatie over de verschillende vermoeiingsstadia, alsook over het finale vermoeiingsstadium. De ontwikkelde magnetische en magnetomechanische karakteriseringstechnieken kunnen gebruikt worden voor de niet-destructieve evaluatie van mechanische en microstructurele eigenschappen, met als doelstelling de beoordeling van de materiaalintegriteit tijdens uitbating en/of voor de kwaliteitscontrole tijdens materiaalproductieprocessen

The twin-screw extrusion technology, an original and powerful solution for the biorefinery of sunflower whole plant

The objective of this study was to evaluate the feasibility of an aqueous process for the biorefinery of sunflower whole plant using a twin-screw extruder. Aqueous extraction of oil was chosen as an environment-friendly alternative to the solvent extraction. The extruder was used to carry out three essential unit operations: grinding, liquid/solid extraction, and liquid/solid separation. Wringing out the mixing was effective. However, drying of the cake meal was not optimal. Lixiviation of cotyledon cells was also incomplete. Extraction efficiency depended on operating conditions: screw rotation speed, and input flow rates of whole plant and water. In the best conditions, oil yield was 57%. Residual oil content in the cake meal was 14%. These conditions leaded to the co-extraction of proteins, pectins, and hemicelluloses. The corresponding protein yield was 44%. Oil was extracted in the form of two oil-in-water emulsions. These hydrophobic phases were stabilized by phospholipids and proteins at interface. An aqueous extract containing part of the water-soluble constituents, mainly proteins and pectins, was also generated. As a mixture of fibers and proteins, the cake meal was molded by thermo-pressing. Panels produced had interesting mechanical properties in bending. The obtained fractions may have applications as bases for industrial products

`Finding Gold In a Gully\u27: Nineteenth-Century Australia in Constructions of British Domesticity From Sensation Fiction to Realism

This thesis investigates nineteenth-century Australia as a frequently disregarded site of colonial discourse where men and women were able to create wealth but unable to transform economic gains into social currency upon return to England and irrevocably weakened English patriarchal authority when they attempted to do so. Unlike many of the other British colonies such as India and Africa, due to its demographics the Australian colonies by and large remained absent from nineteenth-century racial violence, thus allowing greater possibilities for economic advancement and social rehabilitation of disenfranchised English populations. By combining travel narratives with the sensation fiction of Mary Elizabeth Braddon\u27s Lady Audley\u27s Secret (1861), the sensational realism of Charles Dickens\u27s Great Expectations (1861), and the realism of Anthony Trollope\u27s John Caldigate (1879), this thesis examines both the real and imagined influence that the Australian colonies had on the breakdown of patriarchal power in late nineteenth-century England and the subversion of traditional economic and social structures that life in the homeland was based upon. By examining disparate nineteenth-century works, this thesis explores the role that literary genre played in the nineteenth century portrayal of Australia in order to build a better understanding of how English sensation novels reflected, and perhaps in some cases provoked, Victorian imperial fears. While much remains to be done in terms of recovering the aboriginal voices of Australia\u27s native people and the creation of an Australian literary cannon, by studying English perspectives of the colonies and their people, we open up the discussion of Australian colonization and begin to understand the impact that colony had upon the homeland in order to then investigate the impact that homeland had upon the colony

Thermo-mechanical behaviour of the raffinate resulting from the aqueous extraction of sunflower whole plant in twin-screw extruder: manufacturing of biodegradable agromaterials by thermo-pressing

Biorefinery of sunflower whole plant can be realized using a twin-screw extruder. Thermo-mechanical fractionation and aqueous extraction are conducted simultaneously. A filter section is outfitted along the barrel to collect continuously an extract and a raffinate (cake meal). Oil yield obtained is 53%. Proteins are partly extracted at the same time, just as pectins and hemicelluloses. Protein yield is 46%. Cake meal is relatively moist (66% for the moisture content). It is first dried to make easier its conservation. It is largely composed of lignocellulosic fibres (59% of the dry matter) from depithed stalk. Lipid content is 13% of the dry matter or 35% of the oil in whole plant. Protein content is 7% of the dry matter or 45% of the proteins in whole plant. DSC measurements indicate that denaturation of proteins is almost complete in the cake meal. DMTA spectrum of its milled powder reveals a significant peak at high temperature (between 175 and 200°C). As already observed with industrial sunflower cake meal, it can be associated with the glass transition of proteins. As a mixture of fibres and proteins, the cake meal can be considered as a natural composite. It is successfully processed into biodegradable and value-added agromaterials by thermo-pressing. As for DMTA analysis, the glass transition of proteins in the cake meal is also observed with PVT analysis at around 180°C. It makes easier the choice of the best thermo-pressing conditions to produce panels with higher mechanical properties in bending. These properties increase simultaneously with temperature, pressure and time chosen for molding operation. The highest flexural strength at break (11.5 MPa) and the highest elastic modulus (2.22 GPa) are obtained for the next molding conditions: 200°C and 320 kgf/cm2 during 60 s. Drop angle measurements show that the corresponding panel is also the most resistant to water. No significant transition is observed inside this panel above 0°C and until 200°C with DMTA analysis. Proteins ensure the agromaterial cohesion without any phase change in this temperature range, and fibres entanglement also acts like reinforcement. This panel could be used as inter-layer sheets for pallets or for the manufacturing of biodegradable containers (composters, crates for vegetable gardening) by assembly of panels

Thermo-pressing of cake meal from sunflower whole plant, one only operation for two actions : expression of residual oil and molding of biodegradable agromaterials

The starting material used in this study was a cake generated during thermo-mechanical fractionation of sunflower (Helianthus annuus L.) whole plant in a Clextral BC 45 (France) twin-screw extruder. It was slightly deoiled (17.6% dry matter for residual oil content), leading to an oil extraction yield of 46.1% (yield based on the residual oil content in cake). As it was a mixture of fibers and proteins, it could be considered as a natural composite that was processed successfully into fiberboards by thermo-pressing. This study aimed to evaluate the influence of thermo-pressing conditions on oil expression yield during molding and on flexural properties of fiberboards manufactured from this cake. An experimental design with three variables was realized: from 250 to 500 kgf/cm² for pressure applied (in 5 levels), from 60 to 300 s for molding time (in 7 levels), and from 600 to 1200 mg/cm² for cake quantity (in 3 levels). Temperature of the aluminium mold positioned between the two plates of the heated hydraulic press (PEI, France) with 400 tons capacity was 200°C. All fiberboards were cohesive. As an internal binder, proteins ensured the agromaterial cohesion, and fibers entanglement also acted like reinforcement. Thermo-pressing was not only a molding operation. It also consisted in increasing the oil extraction efficiency. Oil expression yield during molding increased with the increase of pressure applied, and especially with the increase of molding time. At the same time, it was not so much influenced by the modification of cake quantity. Highest oil expression yield was 58.8% in proportion to the oil that the cake contained, leading to a total oil yield (oil extracted by water in twin-screw extruder, and oil expressed during molding) of 77.8% in proportion to the oil that the sunflower whole plant contained. It was associated with the next thermo-pressing conditions: 469 kgf/cm² for pressure applied, 300 s for molding time, and 697 mg/cm² for cake quantity. Flexural properties of the corresponding fiberboard were 8.1 MPa for flexural strength at break, and 1778 MPa for elastic modulus. Its thickness was 5.40 mm, leading to a mean apparent density of 1.25. Such flexural strength at break was a bit lower (-25%) than the one of the most resistant fiberboard (10.8 MPa), manufactured from the next thermo-pressing conditions: 250 kgf/cm² for pressure applied, 300 s for molding time, and 807 mg/cm² for cake quantity. For such conditions, oil expression yield was 48.0% in proportion to the oil that the cake contained, leading to a total oil yield close (-8%) to the highest yield obtained (71.9% in proportion to the oil that the sunflower whole plant contained instead of 77.8%). Thermo-pressing of cake from sunflower whole plant led to two actions in a single step: the expression of part of residual oil in cake that contributed to the improvement of the oil extraction efficiency, and the molding of biodegradable fiberboards. Their flexural properties were promising. Moreover, because residual oil content in fiberboards was at least 8.0% dry matter, they were not too water-sensitive (i.e. more durable than other thermo-pressed agromaterials). Such fiberboards were value-added agromaterials that may have direct industrial applications. Indeed, they would be potentially usable as inter-layer sheets for pallets, for the manufacturing of biodegradable containers (composters, crates for vegetable gardening), or for their heat insulation properties in building trade

Child's and parent's catastrophizing about pain is associated with procedural fear in children: a study in children with diabetes and their mothers

The contribution of the child's and parents' catastrophizing about pain was explored in explaining procedural pain and fear in children. Procedural fear and pain were investigated in 44 children with Type I diabetes undergoing a finger prick. The relationships between parents' catastrophizing and parents' own fear and estimates of their child's pain were also investigated. The children and their mothers completed questionnaires prior to a routine consultation with the diabetes physician. Children completed a situation-specific measure of the Pain Catastrophizing Scale for Children (PCS-C) and provided ratings of their experienced pain and fear on a 0-10 numerical rating scale (NRS). Parents completed a situation-specific measure of the Pain Catastrophizing Scale For Parents (PCS-P) and provided estimates of their child's pain and their own experienced fear on a 0-10 NRS. Analyses indicated that higher catastrophizing by children was associated with more fear and pain during the finger prick. Scores for parents' catastrophizing about their children's pain were positively related to parents' scores for their own fear, estimates of their children's pain, and child-reported fear, but not the amount of pain reported by the child. The findings attest to the importance of assessing for and targeting child and parents' catastrophizing about pain. Addressing catastrophizing and related fears and concerns of both parents and children may be necessary to assure appropriate self-management. Further investigation of the mechanisms relating catastrophizing to deleterious outcomes is warranted