This study examined the effects of disk speed, temperature and anvil condition on chip size from sawmill residues of Loblolly pine (<i>Pinus taeda</i> L.). Objectives were: 1) to document the effects of disk speed, temperature and anvil condition on the amount of over thick, oversize, accept, pin and fine chips produced from edgings, 6"x6" cants and trim blocks and 2) to recommend changes in processing sawmill residues to minimize the production of over thick, pin and fine chips. Ten trials were conducted at the Chesapeake Corporation's West Point, Virginia hardwood sawmill using a Fulghum Industries 60-in. (152-cm) diameter, six-knife, vertical disk chipper. Tests were conducted at approximately 80, 70, 60, 50 and 40% of the full disk speed of 707 rpm for the three material types. It was found that decreasing disk speed decreases the amount of pin and fine chips and increases the amount of over thick chips for all material types. The maximum amount of accept and oversize chips was obtained at 50% disk speed. If 50% efficient secondary processing of the over thick chips is achieved, the maximum amount of oversize and accept chips would be produced at 40% disk speed. All frozen and chilled residue types tended to produce less oversize chips and significantly more pins and fines than wood at ambient temperature. A worn anvil caused a significant increase in pins and fines while causing a significant decrease in oversize chips from the cants. Design changes are suggested to reduce the amount of over thick chips produced by vertical disk chippers. / Master of Science

Les matériaux de structure utilisés dans le cœur des REP, comme par exemple les aciers austénitiques ou bien les alliages de zirconium, sont soumis à la fois à une forte irradiation neutronique ainsi qu’à divers chargements mécaniques. A l’échelle macroscopique, le comportement mécanique sous irradiation de ces matériaux est bien caractérisé. Cependant, à l’échelle microscopique, les mécanismes de déformation sous irradiation restent encore mal connus. De nombreux mécanismes de fluage d’irradiation ont été envisagés du point de vue théorique mais les données expérimentales existantes n’ont pu, pour l’heure, permettre de déterminer le mécanisme pertinent contrôlant la déformation.L'objectif de ce travail de thèse est justement d’apporter une contribution à la compréhension des mécanismes de fluage d’irradiation des métaux et alliages par la mise en œuvre d’une méthode expérimentale originale. Les irradiations sont reproduites par des irradiations aux ions lourds. Ces irradiations ont l’avantage de créer un dommage rapide sans activer la matière. Cependant l’épaisseur irradiée n’est que de plusieurs centaines de nanomètres. De telles épaisseurs nécessitent un dispositif expérimental spécifique pour l’application d’une charge sur l’échantillon. Le dispositif utilisé est basé sur l’utilisation de contraintes internes dans un film mince de nitrure de silicium pour déformer des films minces métalliques. Cette méthode a été conçue et développée par les équipes de Thomas Pardoen et Jean-Pierre Raskin à l’université catholique de Louvain, en Belgique.Après une démonstration de la faisabilité de l’étude et une adaptation du dispositif aux conditions d’irradiation, cette méthode a pu être utilisée avec succès pour reproduire une expérience de fluage d’irradiation à température ambiante sur un matériau modèle, le cuivre. Une loi de fluage en puissance 5 selon la contrainte a été trouvée sous irradiation sur des films de 200 et 500 nm d’épaisseur. Les observations au microscope électronique à balayage et en transmission suggèrent que les mécanismes de déformation reposent sur le glissement assisté par la montée.Cette loi apparait indépendante de la microstructure et de l’historique de chargement des éprouvettes. La montée, si elle intervient, ne semble pas contrôlée par des mécanismes de diffusion à longue distance mais par des interactions directes entre la cascade déplacements et les dislocations.Hors irradiation et après irradiation, le comportement mécanique des films a également pu être évalué. Les mécanismes de déformation semblent identiques dans les deux conditions. A vitesse de déformation modérée, la déformation est contrôlée par le glissement intragrannulaire des dislocations tandis qu’à basse vitesse un changement de mécanisme se produit. Le nouveau mécanisme reste toujours basé sur les dislocations mais une composante de glissement aux joints de grains semble apparaitre. Un durcissement post irradiation est observé du fait d’une densité importante de SFT dans les éprouvettes irradiées qui agissent comme des obstacles au glissement des dislocations / Structural materials used in the PWR cores, such as austenitic stainless steels or zirconium alloys, are exposed to a significant neutron flux and, at the same time, a stress from various mechanical loadings. At the macroscopic scale, the mechanical behavior under irradiation is well characterized. However, at a microscopic scale, the deformation mechanisms under irradiation still remain unknown. Many irradiation creep mechanisms have been proposed from a theoretical point of view but the available experimental data have not, for now, permitted to identify the relevant mechanism leading to the deformation.The objective of this thesis is precisely to improve our understanding of the irradiation creep mechanisms of metals and alloys by the development of a novel experimental method. In this method, the irradiation is produced by the use of heavy ions. This kind of irradiation has the advantage of a fast damage rate without an activation of the material. However the irradiated area is confined in a few hundreds of nanometers. Such thickness requires a specific experimental device to apply a stress on the specimen. This device is based on the release of internal stress in a silicon nitride film to deform a metallic thin film. This method was designed and developed at the Université Catholique de Louvain in Belgium by the teams of Thomas Pardoen and Jean-Pierre Raskin.After proving the feasibility of the study and adapting the device to the irradiation environment, the method has been used with success to reproduce an irradiation creep experiment at room temperature on a model material : copper. A single creep power law with a stress exponent of 5 has been found under irradiation on 200 and 500 nm thick films. The SEM and TEM observations suggest that the deformation mechanism rely on the glide of dislocations assisted by climb.This law seems to be independent of the microstructure and the loading history. The dislocation climb, if it occurs, would not be controlled by diffusion process at long distance but by direct interaction between displacement cascades and dislocations.The mechanical behavior of unirradiated and irradiated copper films have also been assessed. The deformation mechanisms seem to be the same in both cases. At a moderate strain rate, the deformation is controlled by the intragrannular glide of dislocations whereas at slow strain rate a change of mechanism takes place. The new mechanism still remains based on dislocations but a component of grain boundary sliding may appear. A post irradiation hardening has been observed on a 200 nm thick film due to the presence, in the irradiated samples, of a high density of SFT which act as obstacles against dislocation glide

This thesis deals with the analysis of the local market in terms of biomass and Less Energy. There is examined the potential of logging residues from the selected area is examined further traffic limit for supplying chips. There are used Porter model analysis.

Studies generally agree on the critical influence of physico-chemical characteristics of raw potatoes on the physico-chemical and sensory characteristics of potato chips. However, the actual magnitude of differences in sensory quality and consumer acceptance of potato chips as a result of differences in the physico-chemical characteristics of raw potatoes are scarcely reported in most studies. This research was conducted to determine the effect of different physico-chemical characteristics of potato samples on the sensory quality and acceptance of potato chips. The potato samples which represented typical variations in physico-chemical characteristics that a potato chip manufacturer experiences were sourced over a six month period. The samples comprised of four potato varieties (A, B, C, D) sourced from five regions (V, W, X, Y, Z). The samples were coded AV, BW1, BW2, CW, CX, DY, DW and DZ. BW1 and BW2 were of the same variety and grown in the same region but harvested at different time periods. The sourcing of potatoes and potato chips were done at the manufacturer’s processing line during regular production. The potatoes were analyzed for physico-chemical characteristics generally reported to influence potato chip sensory quality, i.e. specific gravity (solids contents), starch content and reducing sugars content. After processing, the physico-chemical characteristics i.e. moisture content, colour and oil content of the respective unflavoured potato chip samples were analysed. The sensory qualities of both unflavoured and flavoured (sour cream and onion) potato chips of the respective potato samples were also determined. There were significant differences (p<0.05) in the specific gravity/solids content of the potato samples. The specific gravity and solids content ranged from 1.073 to 1.098g/cm3 and 19.2 to 24.9% respectively. Reducing sugars were not detected in any of the potato samples at a minimum detection level of 0.05 %. The potato chip samples differed significantly (p<0.05) in moisture content, oil content and colour (a * and b* values, chroma, hue angle) with ranges of 1.2 to 1.9 % (moisture), 33.1 to 40.8 % d.b (oil content), 0.39 to 3.69 (a *), 15.88 to 21.26 (b*), 15.93 to 21.37 (chroma) and 79.92 to 88.96 o (hue angle). Descriptive sensory evaluation showed that 6 and 8 of the attributes identified in the unflavoured and flavoured potato chip samples, respectively, differed significantly (p<0.05). Consumer sensory evaluation indicated that there was no clear preference of one chip sample over the others despite of differences observed through descriptive sensory analysis and physico-chemical characteristics. All the chip samples were generally liked. To the manufacturer this research could be regarded as of a quality control nature since the potato chip samples used in this study were of chipping varieties actually used by the manufacturer. The value of this research to the chip manufacturer was the fact that despite of slight differences in the physico-chemical characteristics (specific gravity/solids content and starch content) of potato samples, potato chips of acceptable sensory quality to the consumers were produced. / Dissertation (MSc)--University of Pretoria, 2011. / Food Science / unrestricted

Published Article / The paper highlights the design, development and evaluation of a hybrid convective-far-infrared (FIR) dehydrator for the purpose of drying fruit. The methodology followed is based on an experimental and practical approach. The application of the dryer for this study is aimed at the production of apple chips as well as other types of fruit chips and the more common dried fruit. The fruit dryer proposed uses both infrared energy and convective heating to effectively and efficiently dehydrate apple slices to produce dried apple chips. The apple chips are produced in very short time frames and accomplished by using relatively low heater power. These types of apple chip snacks also contribute to the more healthy variety of snacks available on the market.

Chipping varieties and model systems were used to determine the role of potato constituents on chip color. Composition was evaluated by HPLC and chip color measured using a ColorQuest colorimeter. Reducing sugar (RS) content did not completely explain color quality when present in low concentrations (<60 mg/lOOg). Levels of ascorbic acid, glutamine and a chlorogenic acid isomer, along with RS, showed high correlation with color. Sucrose was a poor estimator of chip color. Model systems used leached potato slices infiltrated with solutions containing sucrose, RS, ascorbic, chlorogenic and amino acids. Linear association of RS with L* and hue angle and quadratic relationship with chroma of chips were found. Ascorbic acid affected chroma and hue at low RS levels while chlorogenic acid was not involved in color development. Red potatoes {Solarium tuberosum and Solarium stenotomum) were evaluated as potential source of natural red colorant. Cultivars (33) were screened for anthocyanin content and qualitative composition. Monomeric anthocyanin content, determined by pH differential, ranged between 4 and 40 mg/lOOg fresh weight (fw) tuber. Varieties 5847-1 and ND04069-4 showed high anthocyanin content (>35 mg/lOOg). Anthocyanin composition was characterized by HPLC, spectral analysis and Mass Spectroscopy (MS). The major anthocyanin was pelargonidin-3-rutinoside-5-glucoside acylated with p-coumaric acid. The presence of glycoalkaloids (α-solanine and α-chaconine) was detected by MS and quantified by HPLC. Varieties NDO4069-4 and 5847-1 showed glycoalkaloid levels of 13 and 7 mg/lOOg fw, respectively. Glycoalkaloids were precipitated from pigment concentrates by alkaline treatment. The best results were obtained at pH 8.0 with 30% monomeric anthocyanin degradation and 90% glycoalkaloid precipitation. The color and pigment stability of chemically related anthocyanin extracts (red-fleshed potatoes and radishes), the effect of pigment purity, and temperature were evaluated in model juices (pH 3.5). Color (CIELch) and anthocyanin degradation was monitored for 65 wks of storage. All model juices showed color similar to FD&C Red # 40. Excellent stability was obtained with all treatments in refrigeration. Anthocyanin structure and extraction method affected pigment stability. At 25°C, higher stability was obtained on juices colored with chemically purified radish anthocyanins (22 wk half-life) and lowest with potato vegetable juice (10 wk half-life). / Graduation date: 1999

A distribuição de temperatura, as deformações e as forças na zona de corte durante a formação de cavacos são muito importantes, pois têm grande influência nos resultados dos processos de usinagem como um todo. O desgaste das ferramentas, a precisão das operações de usinagem (dilatação térmica) e o acabamento superficial são alguns desses resultados que afetam a economia do processo. Este trabalho tem o objetivo uma avaliação das potencialidades oferecidas pela simulação da formação de cavacos usando-se FEM (Finite Element Method). Quatros modelos com princípios bastante diferentes são utilizados explorando-se as mais recentes inovações em termos de recursos oferecidos pelo software ABAQUS/Explicit. Nos modelos utilizam-se ferramentas de substrato WC recoberto com TiN usinado aços AISI 4340. As simulações proporcionam o estudo e exame detalhado da distribuição de temperatura, deformações, forças de corte, fluxo de material e uma enorme quantidade de informações que poderão ser muito úteis para a análise de novos processos, otimização de processos existentes, além de abrir novos horizontes no estudo da formação de cavacos. As simulações também demonstram que a complexidade da formação de cavacos cria muitas dificuldades para sua análise usando equações analíticas baseadas em constantes. / The distribution of temperature, the deformations and the cutting forces in the cutting zone during chip formation are very important aspects of the process. Therefore they have great influence in results of machining. Tool wear, the precision of the machining operations and the finishing superface are some of these results that affect the economy of the process. This work has the objective of an evaluation offered potentialities for simulating chip formation using FEM (Finite Element Method). Four models with sufficiently different principles are used to exploring the most recent innovations in terms of resources offered by ABAQUS/Explicit software. In the models, WC tools coated TiN was used to machine AISI 4340 steel. The simulations provide a study and detailed examination of temperature distribution, deformations, cutting forces, flow of material and an enormous amount of information that could be useful for the analysis of new processes and optimization of existing processes. Additionally, they open new horizon in the study of the chip formation. The simulations also demonstrate the complexity of the chip formation process, which creates many difficulties for its analysis using based analytical equations in constants. Some comparisons are established with experimental results found in temperature measurements.

A distribuição de temperatura, as deformações e as forças na zona de corte durante a formação de cavacos são muito importantes, pois têm grande influência nos resultados dos processos de usinagem como um todo. O desgaste das ferramentas, a precisão das operações de usinagem (dilatação térmica) e o acabamento superficial são alguns desses resultados que afetam a economia do processo. Este trabalho tem o objetivo uma avaliação das potencialidades oferecidas pela simulação da formação de cavacos usando-se FEM (Finite Element Method). Quatros modelos com princípios bastante diferentes são utilizados explorando-se as mais recentes inovações em termos de recursos oferecidos pelo software ABAQUS/Explicit. Nos modelos utilizam-se ferramentas de substrato WC recoberto com TiN usinado aços AISI 4340. As simulações proporcionam o estudo e exame detalhado da distribuição de temperatura, deformações, forças de corte, fluxo de material e uma enorme quantidade de informações que poderão ser muito úteis para a análise de novos processos, otimização de processos existentes, além de abrir novos horizontes no estudo da formação de cavacos. As simulações também demonstram que a complexidade da formação de cavacos cria muitas dificuldades para sua análise usando equações analíticas baseadas em constantes. / The distribution of temperature, the deformations and the cutting forces in the cutting zone during chip formation are very important aspects of the process. Therefore they have great influence in results of machining. Tool wear, the precision of the machining operations and the finishing superface are some of these results that affect the economy of the process. This work has the objective of an evaluation offered potentialities for simulating chip formation using FEM (Finite Element Method). Four models with sufficiently different principles are used to exploring the most recent innovations in terms of resources offered by ABAQUS/Explicit software. In the models, WC tools coated TiN was used to machine AISI 4340 steel. The simulations provide a study and detailed examination of temperature distribution, deformations, cutting forces, flow of material and an enormous amount of information that could be useful for the analysis of new processes and optimization of existing processes. Additionally, they open new horizon in the study of the chip formation. The simulations also demonstrate the complexity of the chip formation process, which creates many difficulties for its analysis using based analytical equations in constants. Some comparisons are established with experimental results found in temperature measurements.

Atom chips are devices used to magnetically trap and manipulate ultracold atoms and Bose-Einstein condensates near a surface. In particular, permanent magnetic film atom chips can allow very tight confinement and intricate magnetic field designs while circumventing technical current noise. Research described in this thesis is focused on the development of a magnetic film atom chip, the production of Bose-Einstein condensates near the film surface, the characterisation of the associated magnetic potentials using rf spectroscopy of ultracold atoms and the realisation of a precision sensor based on splitting Bose-Einstein condensates in a double-well potential. The atom chip itself combines the edge of a perpendicularly magnetised GdTbFeCo film with a machined silver wire structure. A mirror magneto-optical trap collects up to 5 x 108 87Rb atoms beneath the chip surface. The current-carrying wires are then used to transfer the cloud of atoms to the magnetic film microtrap and radio frequency evaporative cooling is applied to produce Bose-Einstein condensates consisting of 1 x 105 atoms. We have identified small spatial magnetic field variations near the film surface that fragment the ultracold atom cloud. These variations originate from inhomogeneity in the film magnetisation and are characterised using a novel technique based on spatially resolved radio frequency spectroscopy of the atoms to map the magnetic field landscape over a large area. The observations agree with an analytic model for the spatial decay of random magnetic fields from the film surface. Bose-Einstein condensates in our unique potential landscape have been used as a precision sensor for potential gradients. We transfer the atoms to the central region of the chip which produces a double-well potential. A single BEC is formed far from the surface and is then dynamically split in two by moving the trap closer to the surface. After splitting, the population of atoms in each well is extremely sensitive to the asymmetry of the potential and can be used to sense tiny magnetic field gradients or changes in gravity on a small spatial scale.

A logical control extension surrounding cashless means of exchange is a permanent personal verification mark. An implanted micro chip such as ones that have been successfully implanted into humans could identify and store information. Connected with global positioning satellites and a computer system, a cashless monetary system could be formed in the future. The system would provide complete and continual real time records for individuals, businesses and regulators. It would be possible for all trading to occur in this way in the future. A modified Technology Acceptance Model was developed based on Davis' (1989) model and Fishbein and Ajzen's (1975) theory to test the acceptance level of the new monetary system by professional accountants in Australia. The model includes perceived ease of use, perceived usefulness, perceived risk, and a subjective norm component. 523 accountants were surveyed in December 2003 with a response rate of 27%. 13% either strongly agree d or agreed that they would accept the implantable chip. The analysis showed that Perception of Risk, Subjective Norm and Perception of Usefulness were all significant in explaining the dependent variable at the 95% confidence level. The Perception of Ease of Use was not proved to be significant. In consideration of response bias, it was found that with respect to the perception of usefulness at the 0.01 level, two elements were not significant, those being