京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第17899号 / 農博第2022号 / 新制||農||1017(附属図書館) / 学位論文||H25||N4795(農学部図書室) / 30719 / 京都大学大学院農学研究科食品生物科学専攻 / (主査)教授 安達 修二, 教授 入江 一浩, 教授 谷 史人 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・論文博士 / 博士(農学) / 乙第13074号 / 論農博第2844号 / 新制||農||1046(附属図書館) / 学位論文||H29||N5030(農学部図書室) / 33225 / (主査)教授 安達 修二, 教授 谷 史人, 教授 橋本 渉 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Antioxidant compounds were extracted from canola meal by subcritical water extraction (SWE), hot water (80°C) extraction and ethanolic (95%) extraction. The highest extract yields were obtained with SWE at 160°C, and the lowest with ethanolic extraction (SWE 160°C > SWE sequential > SWE 135°C > SWE 110°C = hot water extraction > ethanolic extraction). Ethanolic extracts exhibited the highest total phenolics contents and Trolox equivalent antioxidant capacity (TEAC) values on a per gram of extract basis, and hot water extracts, the lowest (ethanolic extraction > SWE 110°C > SWE 160°C > hot water extraction). Extraction pressure (3.44-6.89 MPa) had no effect on the yields, total phenolics contents or TEAC values of extracts from SWE. The use of buffered water (pH 2-8) for SWE increased extract yield but had adverse effects on the total phenolics contents and TEAC values of extracts. No increase in efficacy of SWE at 110 or 160°C was observed at extraction times longer than 25-30 min. The total phenolics contents and antioxidant capacities of extracts were assessed by the total phenolics assay, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging method, TEAC method, the β-carotene-linoleic acid (linoleate) model system, the reducing power assay and the stripped oil model system. Ethanolic extracts exhibited the highest total phenolic contents and antioxidant capacities on a per gram of extract basis. Subcritical water extraction at 160°C exhibited the highest total phenolic contents and antioxidant capacities on a per gram of meal basis. Results from the total phenolics assay and the antioxidant capacity assays were significantly correlated, with the exception of those from the stripped oil model system.

Antioxidant compounds were extracted from canola meal by subcritical water extraction (SWE), hot water (80°C) extraction and ethanolic (95%) extraction. The highest extract yields were obtained with SWE at 160°C, and the lowest with ethanolic extraction (SWE 160°C > SWE sequential > SWE 135°C > SWE 110°C = hot water extraction > ethanolic extraction). Ethanolic extracts exhibited the highest total phenolics contents and Trolox equivalent antioxidant capacity (TEAC) values on a per gram of extract basis, and hot water extracts, the lowest (ethanolic extraction > SWE 110°C > SWE 160°C > hot water extraction). Extraction pressure (3.44-6.89 MPa) had no effect on the yields, total phenolics contents or TEAC values of extracts from SWE. The use of buffered water (pH 2-8) for SWE increased extract yield but had adverse effects on the total phenolics contents and TEAC values of extracts. No increase in efficacy of SWE at 110 or 160°C was observed at extraction times longer than 25-30 min. The total phenolics contents and antioxidant capacities of extracts were assessed by the total phenolics assay, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging method, TEAC method, the β-carotene-linoleic acid (linoleate) model system, the reducing power assay and the stripped oil model system. Ethanolic extracts exhibited the highest total phenolic contents and antioxidant capacities on a per gram of extract basis. Subcritical water extraction at 160°C exhibited the highest total phenolic contents and antioxidant capacities on a per gram of meal basis. Results from the total phenolics assay and the antioxidant capacity assays were significantly correlated, with the exception of those from the stripped oil model system.

Chelate Assisted, Pressurized, Liquid Extraction (CAPLE) has been developed in our laboratory as an efficient, separation-based, extraction methodology for heavy metals in soils. Unlike current extraction methods used in environmental determination of contaminated soils, CAPLE is able to selectively remove adsorbed metals from the soil matrix without requiring the total destruction of the sample. By not fracturing the soil matrix particles, as with hot acid digestion methods, geologically bound metals are not liberated in the CAPLE process. This unique feature of CAPLE allows us to quantify levels of contaminant metals and correlate them to anthropological activity in the area. CAPLE requires the use of a modified supercritical fluid extractor for operation with water at sub-critical levels. The extraction of the sorbed metals is facilitated by the use of a chelating agent. Metal determinations are performed by atomic absorption (FAAS or GFAAS) or ICP emission spectrometry. CAPLE has been subjected to a variety of experimental conditions in order to elucidate the strengths and possible weaknesses of the extraction technique. The uses of the chelating agents (type and concentration) have been optimized. Possible release of metals from the resulting ionic strength of the chelating solutions have been shown not to be a factor. Both pressure and temperature effects have been studied and adjusted for optimal conditions. The majority of the research lies in the application of CAPLE to a variety of soil conditions. The effect on particle size of the soil and soil coating (humic acid and iron oxides) has been studied. In all soil systems and coatings studied, CAPLE could be optimized to completely remove chemisorbed metals. Tests of CAPLE on Cu-sludge amended soils provided excellent agreement with traditional methods of soil analysis. Not only was good agreement obtained between the recoveries of the methods, but CAPLE was also found to be much faster, more environmentally friendly, and much less prone to sample loss or sample contamination compared to traditional soil extraction methods. A final portion of this work involves a rigorous statistical analysis of CAPLE to a sequential extraction method. Since a Standard Reference Material (SRM) has not been provided for chemisorbed metals onto soils, a comparative analysis was chosen to validate the technique. Using the Cu-amended soils, CAPLE was found to effectively liberate all chemisorbed metals as compared to the sequential extraction technique. There was no statistical difference in recovery between the two extraction methods. CAPLE is shown in this work to be a viable extraction method for analyzing contaminant metals in soils. It is a rapid and efficient technique. Unlike traditional digestion methods, it is able to differentiate anthropological metals from geologically occurring metals. Its ease of use, coupled with simplicity of instrumental design and analytical reagents make it an attractive extraction technique for environmental analysis. / Ph. D.

The transport of heat out of tokamak plasmas by turbulence is the dominant mechanism limiting the performance of fusion reactors. Turbulence can be driven by the ion temperature gradient (ITG) and suppressed by toroidal equilibrium scale sheared flows. Numerical simulations attempting to understand, and ultimately reduce, turbulence are crucial for guiding the design and optimisation of future reactors. In this thesis, we investigate ion-scale turbulence by means of local gyrokinetic simulations in the outer core of the Mega Ampere Spherical Tokamak (MAST).We perform a parameter scan in the values of the ITG and the flow shear. We show that nonlinear simulations reproduce the experimental ion heat flux and that the experimentally measured values of the ITG and the flow shear lie close to the turbulence threshold. We demonstrate that the system is subcritical in the presence of flow shear, i.e., the system is formally stable to small perturbations, but transitions to a turbulent state given a large enough initial perturbation. We propose a scenario for the transition to subcritical turbulence previously unreported in tokamak plasmas: close to the threshold, the plasma is dominated by a low number of coherent long-lived structures; as the system is taken away from the threshold into the more unstable regime, the number of these structures increases until they fill the domain and a more conventional turbulence emerges. We make quantitative comparisons of correlation properties between our simulations and experimental measurements of ion-scale density fluctuations from the MAST BES diagnostic. We apply a synthetic diagnostic to our simulation data and find reasonable agreement of the correlation properties of the simulated and experimental turbulence, most notably of the correlation time, for which significant discrepancies were found in previous numerical studies of MAST turbulence. We show that the properties of turbulence are essentially functions of the distance to threshold, as quantified by the ion heat flux. We find that turbulence close to the threshold is strongly affected by flow shear, whereas far from threshold, the turbulence resembles a conventional ITG-driven, zonal-flow damped regime.

The transport of heat that results from turbulence is a major factor limiting the temperature gradient, and thus the performance, of fusion devices. We use nonlinear simulations to show that a toroidal equilibrium scale sheared flow can completely suppress the turbulence across a wide range of flow gradient and temperature gradient values. We demonstrate the existence of a bifurcation across this range whereby the plasma may transition from a low flow gradient and temperature gradient state to a higher flow gradient and temperature gradient state. We show further that the maximum temperature gradient that can be reached by such a transition is limited by the existence, at high flow gradient, of subcritical turbulence driven by the parallel velocity gradient (PVG). We use linear simulations and analytic calculations to examine the properties of the transiently growing modes which give rise to this subcritical turbulence, and conclude that there may be a critical value of the ratio of the PVG to the suppressing perpendicular gradient of the velocity (in a tokamak this ratio is equal to q/ε where q is the magnetic safety factor and ε the inverse aspect ra- tio) below which the PVG is unable to drive subcritical turbulence. In light of this, we use nonlinear simulations to calculate, as a function of three parameters (the perpendicular flow shear, q/ε and the temperature gradient), the surface within that parameter space which divides the regions where turbulence can and cannot be sustained: the zero- turbulence manifold. We are unable to conclude that there is in fact a critical value of q/ε below which PVG-driven turbulence is eliminated. Nevertheless, we demonstrate that at low values of q/ε, the maximum critical temperature gradient that can be reached without generating turbulence (and thus, we infer, the maximum temperature gradient that could be reached in the transport bifurcation) is dramatically increased. Thus, we anticipate that a fusion device for which, across a significant portion of the minor radius, the magnetic shear is low, the ratio q/ε is low and the toroidal flow shear is strong, will achieve high levels of energy confinement and thus high performance.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第19754号 / 農博第2150号 / 新制||農||1038(附属図書館) / 学位論文||H28||N4970(農学部図書室) / 32790 / 京都大学大学院農学研究科食品生物科学専攻 / (主査)教授 安達 修二, 教授 入江 一浩, 教授 保川 清 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

No description available.

Presence of nonlinearities may lead to limit cycle oscillations (LCOs) in aeroelastic systems. LCOs can result in fatigue in wings leading to catastrophic failures. Existence of LCOs for velocities less than the linear flutter velocity has been observed during flight and wind tunnel tests, making such subcritical behavior highly undesirable. The objective of this dissertation is to investigate the existence of subcritical LCOs in aeroelastic systems and develop state feedback controllers to suppress them. The research results are demonstrated on a two degree of freedom airfoil section model with stiffness nonlinearity. Three different approaches are developed and discussed. The first approach uses a feedback linearization controller employing the aeroelastic modal coordinates. The use of modal coordinates results in a system which is linearly decoupled making it possible to avoid cancellation of any linear terms when compared to existing feedback linearization controllers which use the physical coordinates. The state and control costs of the developed controller are compared to the costs of the traditional feedback linearization controllers. Second approach involves the use of nonlinear normal modes (NNMs) as a tool to predict LCO amplitudes of the aeroelastic system. NNM dynamics along with harmonic balance method are used to generate analytical estimates of LCO amplitude and its sensitivities with respect to the introduced control parameters. A multiobjective optimization problem is solved to generate optimal control parameters which minimize the LCO amplitude and the control cost. The third approach uses a nonlinear state feedback control input obtained as the solution of a multiobjective optimization problem which minimizes the difference between the LCO commencement velocity and the linear flutter velocity. The estimates of LCO commencement velocity and its sensitivities are obtained using numerical continuation methods and harmonic balance methods. It is shown that the developed optimal controller eliminates any existing subcritical LCOs by converting them to supercritical LCOs. / Ph. D.