名古屋大学年代測定総合研究センターシンポジウム報告

With the technological development in biologically orientated industries more and more natural products in powdered form are being handled and processed. Three differently comminuted liquorice rhizome products were classified into 23 narrow size fractions to investigate the particle and bulk characteristics of the material, and to study the influence of particle shape on powder flowability. The morphology of the fibrous particulate was investigated by using a Quantimet 720 Image Analyser. The perimeter (P), projected area (A), breadth (B), length (L), horizontal and vertical projected lengths (P V and Pi) and the horizontal and vertical Feret diameters (FV FH) were measured from which four dimensionless shape factors were evaluated, [P2/47rA, PHxPV/A, L/B, FV/FH]. The surface texture of the particles was measured by fractal analysis. The influence of particle shape and size on the mean flow rate, coefficient of flow variation and flow uniformity were measured using a specially designed inclined tube flowmeter. The failure properties of powdered liquorice when sheared under known normal compressive stresses were measured and from a series of yield loci the unconfined yield strength, major consolidation stress and effective angle of internal friction were obtained. The effects of particle shape and size on the angle of internal friction, wall friction, bulk and packed densities were. investigated and the experimental correlations expressed in terms of mathematical equations. These relationships, together with the failure function plots, indicate that comminuted liquorice powder behaves as a "simple" powder.

The Publish/Subscribe (pub/sub) model has been widely applied in a variety of application scenarios which demand loose-coupling and asynchronous communication between a large number of information sources and sinks. In this model, clients are granted the flexibility to specify their interests at a high level and rely on the pub/sub middleware for delivery of their publications of interest. This increased flexibility and ease of use on the client side results in substantial complexity on part of the pub/sub middleware implementation. Furthermore, for several reasons including improved scalability, availability and avoiding a single point of failure, the pub/sub middleware is commonly composed of a set of collaborating message routers, a.k.a. brokers. The distributed nature of this design further introduces new challenges in ensuring end-to-end reliability as well as efficiency of operation. These challenges are largely unique to the pub/sub model and hence absent in both point-to-point or multicast protocols. This thesis develops solutions that ensure the dependable operation of the pub/sub system by exploiting the notion of overlay neighborhoods in a formal manner. More specifically, brokers maintain information about their neighbors within a configurable distance in the pub/sub overlay and exploit this knowledge to construct alternative forwarding paths or make smart forwarding decisions that improves efficiency, bandwidth utilization and delivery delay, all at the same time. Furthermore, in the face of failures overlay neighborhoods enable fast reconstruction of forwarding paths in the system without compromising its reliability and availability. Finally, as an added benefit of overlay neighborhoods, this thesis develops large-scale algorithms that bring the advantages of the pub/sub model to the domain of file sharing and bulk content dissemination applications. Experimental evaluation results with deployments as large as 1000 nodes illustrate that the pub/sub system scales well and outperforms the traditional BitTorrent protocol in terms of content dissemination delay.

Poly(2-Hydroxyethyl acrylate), PHEA, is used as hydrophilic polymeric gels which have been studied because of its great importance for agricultural or biomedical applications. Biomedical applications of hydrogels include soft contact lenses, artificial corneas, soft tissue substitutes and burn dressings. In this study, it was aimed to synthesis the polymers with well-defined molecular weights, polydispersities and cahin topologies. Bulk, solution and atom transfer radical polymerization (ATRP) techniques at different temperatures were examined. The polymerization in bulk form was carried in vacuum and in open atmosphere. The polymerization curves showed autoacceleration mechanism. The polymers obtained were insoluable in most common solvents because of having high molecular weights and are crosslinked. So in order to overcome this problem, 2-hydroxyethyl acrylate was polymerized by solution and ATRP methods. The activation energy for bulk polymerization was found from Arrhenius plot. The polymer was characterized by FT-IR, DSC, TGA, 1H and 13C NMR techniques, Tensile tests were also examined for PHEA.

The interdependencies that exist within and between infrastructures can cause unexpected system properties to emerge when their components fail due to large disruptions. As witnessed following emergencies such as Hurricane Katrina, the complexities of these interdependencies make it very difficult to effectively recover infrastructure because of the challenges they create in prioritizing the most critical components for repair. The Joint Infrastructure Interdependencies Research Program was initiated by Public Safety Canada (PSC) and the Natural Sciences and Engineering Research Council of Canada (NSERC) in 2005 to research methods for remedying this problem. As a part of this research, the University of British Columbia (UBC) is developing an infrastructure interdependency simulator, named I2Sim, to simulate disasters and develop strategies for dealing with emergencies. Part of this development is to construct a model of the UBC electrical distribution system and interface it with I2Sim. In this research, a general methodology for such a model is presented, which employs an off-the-shelf powerflow modeling tool. In addition, a model of the UBC information technology infrastructure is developed to provide a second infrastructure model to demonstrate the electrical model's usefulness in multi-infrastructure disaster recovery simulations. Simulations with these models have shown that the recovery of this two-infrastructure system can be carried out more effectively following an earthquake if both infrastructures are considered together in the repair approach, rather than individually. This difference was on the order of thirty percent. To extend this research from electrical distribution systems to electrical bulk systems, an interdependency model of the British Columbia Transmission Corporation bulk power network and its communications system was also developed, along with a post-blackout restoration procedure. Using these, simulations of a post-blackout recovery were carried out to study the level of risk that communications outages may pose to the electrical network's recovery. These simulations revealed a correlation between restoration time and the number of communication points lost. This research also demonstrates there is value in combining the results of such simulations with risk evaluation tools. Together these results provided a clearer indication of where vulnerabilities exist.

This thesis is an investigation into the accuracy of hybrid density functional theory to predict the properties of two transition metal oxides: Ilmenite (FeTiO3) and haematite (sigma-Fe2O3). The hybrid density functional theory examined is Becke's B3LYP functional, which is an empirical mix of density functional theory and exact nonlocal exchange from Hartree-Fock theory. For bulk ilmenite, results from the B3LYP functional are compared with Hartree-Fock and pure density functional theory calculations. The computed properties are found to be very sensitive to the treatment of electronic exchange and correlation, with the best results being achieved using the hybrid functional. Calculations performed using the hybrid functional benefit from its better treatment of the electronic self interaction and its reasonable estimate of the pair correlation energy of the doubly occupied Fe-d orbital. To assess the performance of the hybrid functional in simulating Fe2O3 and FeTiO3 with different cation-anion coordination than that found in ilmenite or haematite, studies were performed on their high pressure polymorphs, for which there are a range of experimental results for comparison. This tests the transferability of the functional before examining cases, such as the surfaces of these materials, where there are little or no experimental or theoretical results. For the currently known high pressure polymorphs of ilmenite and haematite, the structural and elastic parameters computed using the hybrid functional are found to be in good agreement with those observed, as is the predicted stability of the phases. In ilmenite, the calculations predict the stability of a new high-pressure polymorph with space group Cmcm, occurring at pressures above 44 GPa. Calculations of the high pressure polymorphs of haematite involve the examination of a range of charge, spin, and magnetic states for each of the polymorphs. Magnetic ordering was found to be important for all the polymorphs, and for each polymorph an antiferromagnetic ordering was found to be lower in energy than the ferromagnetic ordering. The predicted transition pressure from the corundum structure and the magnetic collapse of the Fe3+ cations were in good agreement with experiment. At high pressures the lowest energy configuration for the orthorhombic perovskite structure was computed to occur with mixed high-spin /low-spin Fe3+ cations, in contrast to predictions in the literature of a Fe2+/Fe4+ solution. The CaIrO3-type structure was also computed to be stable with a mixed high-spin/ low-spin Fe3+ configuration at high pressures, and is computed to be the most stable polymorph at pressures above 46 GPa at 0 K. The structure of the ilmenite (0001) surface is examined using the B3LYP functional, and for this surface twelve different terminations are considered, with surface energies and relaxed geometries calculated. The Fe terminated (0001) surface was found to have the lowest cleavage energy, and also to be the most stable surface at low oxygen partial pressures suggesting it is most likely to form when ilmenite is cleaved under high vacuum.

Storage of granular solids in silos has been the practice for many years. Engineers have been faced with the problem of making the silos empty more efficiently and minimising the forces acting on the walls of the silo during material discharge. To this end the anti-dynamic tube was invented. The tube has a smaller diameter than the silo and consists of several portholes along its height and around its circumference. When the discharge gate of the silo is opened the granular material enters the tube through the portholes, flows down the inside of the tube and exits the silo through the discharge gate. Most tubes have been installed such that there was sufficient space between the base of the tube and silo bottom for the granular material to flow simultaneously through the discharge gate. The flowing material causes a down drag on the tube from the friction of the granular material on the walls of the tube. Previous research has underestimated the magnitude of these frictional forces resulting in catastrophic buckling failure of the tubes, blocking the discharge gate of the silo. A blockage of the discharge gate requires top emptying of the silo resulting in financial losses and down time of equipment. A steel model silo with an anti-dynamic tube was set up in the laboratory to measure the friction on the tube during material flow. From the results of these experiments, an equation has been derived to estimate the magnitude of the down-drag force. Furthermore, an empirical expression was developed for the effects of the speed of the flowing material on the magnitude of the down-drag force. To keep construction costs down, it is necessary to optimise the wall thickness of the tube. There is currently no theory for the buckling capacity of a thin walled cylindrical shell with multiple perforations around its height and circumference. Therefore additional experiments were undertaken on a cylindrical shell with multiple perforations subjected to a combination of an axial as well as an external lateral pressure. Following on from the experiments, finite element analyses were undertaken to compare with the experimental results. For each finite element analysis an out-of-roundness was introduced as an initial wall imperfection. From these analyses and the cylinder experiments, a method of producing interaction curves for tubes with varying ratios of open area has been developed.

Thesis (Ph.D.)--University of Western Australia, 2003.

Al based alloy powders (Al₈₅Ni₅Y₆Co₂Fe₂) are produced by spray atomization method. High energy ball milling is done to modify the surface topology and particle size for better electrochemical performance. X ray diffraction (XRD), differential scanning calorimeter (DSC), scanning electron microscope (SEM) and transmission electron microscope (TEM) were conducted to characterize the microstructure of the alloys after ball milling. It is found that 5 hours ball milling gives the minimum crystallization and structure change. Thin film sample is also deposited on stainless steel substrate by pulsed laser deposition (PLD) method for electrochemical test. The capacity and reversibility for different samples are compared and discussed. A capacity of 200mAh/g is obtained for the battery with thin film sample as anode and a capacity of 140mAh/g is obtained for that with electrode from powder sample. Both of the batteries give up to 94% capacity retention after 20 cycles. / Singapore-MIT Alliance (SMA)

Orientador: Helio Langoni / Resumo: A refrigeração é um importante método de conservação do leite, porém quando ocorre por longo período, a qualidade desse produto pode ser alterada devido, principalmente, a multiplicação de bactérias psicrotróficas. Dentro desse grupo de micro-organismos, entre os gêneros patogênicos, destaca-se Listeria monocytogenes. A identificação deste patógeno em alimentos é de interesse não somente pelos efeitos nocivos aos animais, mas também pelos efeitos na saúde humana. O objetivo do presente estudo foi investigar a presença de L. monocytogenes em 95 amostras de leite bovino de conjunto de pequenas propriedades leiteiras de agricultura familiar. As amostras de leite foram cultivadas nos meios seletivos de PALCAM e ALOA e as colônias características foram avaliadas por métodos fenotípicos e moleculares, pela Reação em Cadeia da Polimerase (PCR), para detecção de L. monocytogenes. Apesar dos resultados negativos no cultivo e na PCR, a patogenicidade de L. monocytogenes para os animais e os riscos em saúde pública, justificam estudos continuados para vigilância epidemiológica do agente em produtos de origem animal como o leite. / Abstract: Refrigeration is an important milk preservation method. However, milk quality may deteriorate if the product is refrigerated for long periods, mainly due to the growth of psychrotrophic bacteria. This group of microorganisms includes pathogenic genera, most notably Listeria monocytogenes. The detection of this bacterium in food is important, given its pathogenic effects on human and animal health and also its economic relevance. This study focused on detecting the presence of L. monocytogenes in milk samples collected at small family-owned dairy farms. Samples were cultivated on PALCAM and ALOA agars for microbiological analysis and a molecular analysis by polymerase chain reaction (PCR) was performed for the detection of L. monocytogenes. Despite the negative results obtained in both these analyses, further studies are recommended to confirm or refute the negligible effect of L. monocytogenes on small dairy farms. / Mestre