京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22768号 / 工博第4767号 / 新制||工||1745(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 田中 宏明, 教授 清水 芳久, 教授 藤井 滋穂 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

A reusable oxidizer-cooled annular aerospike nozzle was designed for testing on a labscale PMMA-N20[1] hybrid rocket motor at Cal Poly-SLO.[2] The detailed design was based on the results of previous research involving cold-flow testing of annular aerospike nozzles and hot-flow testing of oxidizer-cooled converging-diverging nozzles. In the design, nitrous oxide is routed to the aerospike through a tube that runs up the middle of the combustion chamber. The solid fuel is arranged in an annular configuration, with a solid cylinder of fuel in the center of the combustion chamber and a hollow cylinder of fuel lining the circumference of the combustion chamber. The center fuel grain insulates the coolant from the heat of the combustion chamber. The two-phase mixture of nitrous oxide then is routed through channels that cool the copper surface of the aerospike. The outer copper shell is brazed to a stainless steel core that provides structural rigidity. The gaseous N2O flows from the end of aerospike to provide base bleed, compensating for the necessary truncation of the spike. Sequential and fully-coupled thermal-mechanical finite element models developed in Abaqus CAE were used to analyze the design of the cooled aerospike. The stress and temperature distributions in the aerospike were predicted for a 10-sec burn time of the hybrid rocket motor. [1] PMMA stands for polymethyl methacrylate, a thermoplastic commonly known by the brand name Plexiglas®. N2O is the molecular formula for nitrous oxide. [2] California Polytechnic State University, San Luis Obispo

Bakgrund: Procedurrelaterad smärta och oro kan innebära ett lidande för barn inom sjukvården vilket kan medföra att barn bygger upp en sjukvårdsrädsla. Ett sätt att lindra det kan vara genom avledning, information samt låta barnet vara delaktigt i sin vård. När det inte är tillräckligt kan lustgas användas eftersom det ger både smärtlindrande och lugnande effekt. Syfte: Att undersöka sjuksköterskors erfarenheter av att använda lustgas till barn vid procedurrelaterad smärta ochoro. Metod: Studien genomfördes utifrån kvalitativ design. Tio sjuksköterskor intervjuades genom en semistrukturerad intervjuguide. Materialet analyserades utifrån en kvalitativ metod. Resultat: Resultatet presenteras i tre kategorier och åtta underkategorier. Kategorierna innefattar: Skapa en optimal situation, Lustgas är en effektiv metod men bör inte vara det enda alternativet och Erfarenhet och utbildning ger trygghet. Barn ska bli informerade och vara delaktiga i sin vård. Lustgas är en effektiv metod men andra avledningsmetoder bör provas först och mindre erfarna sjuksköterskor kan känna osäkerhet. Konklusion: Lustgas är en effektiv metod. Genom att involvera barn i sin vård ökar deras delaktighet. Därtill behöver sjuksköterskor fortlöpande lustgasutbildning för att känna trygghet. Det skulle kunna bidra till en förbättrad lustgasanvändning och en optimal barnsjukvård. / Background: Procedure-related pain and anxiety can cause suffering to children in healthcare, which can lead to children building up a fear of healthcare. One way to alleviate this can be by distraction, information and letting the child be involved in their care. When it is not enough nitrous oxide can be used since it provides both a pain relieving and a calming effect. Purpose: To examine nurses’ experiences of using nitrous oxide to children during procedure-related pain and anxiety. Method: The study was conducted through a qualitative design. Ten nurses were interviewed based on a semi-structured interview guide. The material was analyzed based on a qualitative content analysis. Result: The result is presented in three categories and eight sub-categories. The categories include: Create an optimal situation, Nitrous oxide is an effective method but should not be the only option and Experience and education provides security. Children should be informed and involved in their care. Nitrous oxide is an effective method but other distraction methods should be tried first and less experienced nurses may feel insecure. Conclusion: Nitrous oxide is an effective method. By involving children in their care, their participation increases. In addition, nurses need continuous nitrous oxide training to feel safe. It could contribute to improved nitrous oxide use and optimal pediatric care.

The reduction of the emission of greenhouse gases to the atmosphere will be one of the challenges that society will have to face in the coming years. Until now, all efforts have been put in improving the properties of the discharged water in a wastewater treatment plant and the efficiency of the whole process. But little effort has been done in measuring and controlling the greenhouse gas emissions. For this reason, the production of nitrous oxide when treating wastewater has become of great concern. Several measurements in laboratory scale and full scale have been done and a wide range of results have been obtained. On the other hand, Himmerfjärden wastewater treatment plant has a deammonification plant for treating rejected water produced when dewatering sludge. It consists of an efficient technology where less energy is supplied and no extra carbon source is added. However, it is unknown the efficiency of this system in terms of nitrous oxide production. For this reason, an analysis was carried out from the 19th June to the 2nd of July. In the light of the results obtained, the deammonification process has obtained better results than conventional nitrification and denitrification in terms of nitrous oxide emissions.

No description available.

Le radical OH est le principal oxydant de l'atmosphère diurne. Celui-ci est donc au cœur d'une chimie complexe mettant en jeu d'autres espèces radicalaires formant ainsi un cycle appelé cycle radicalaire. Il est ainsi responsable de la transformation de la majorité des composés émis ou formés dans l'atmosphère et donc de la formation de polluants secondaires, tels que l'ozone ou les aérosols organiques secondaires, pouvant avoir des effets très néfastes pour la santé humaines ou des effets non négligeables sur le climat. Une des principales sources conduisant à l'initiation de ce cycle est la photolyse de l'acide nitreux. Or, la nature et l'intensité des sources de l'acide nitreux sont encore sujettes à débat. L'objectif de ma thèse était donc d'étudier cette chimie radicalaire ainsi que la chimie de l'acide nitreux dans divers environnements afin d'améliorer la compréhension des processus d'oxydation sévissant dans l'atmosphère. Pour répondre à ces objectifs, ce travail de thèse s'est appuyé sur les résultats collectés lors de campagnes de terrains menées dans des environnements différents et à des saisons variées : les campagnes MEGAPOLI été et hiver qui se sont déroulées dans un environnement suburbain de la banlieue de Paris à l'été 2009 et à l'hiver 2010 et enfin la campagne CalNEX qui s'est déroulée dans un environnement pollué de la banlieue de Los Angeles durant le printemps 2010.En s'appuyant sur les résultats de ces campagnes, une méthodologie consistant en l'utilisation de calcul simple type hypothèse de l'état quasi-stationnaire ou plus complexe type modélisation 0D incluant un schéma chimique détaillé (le MCM) et contraint avec l'ensemble des mesures, a été développée et comparée avec les mesures de concentrations de radicaux afin de tester l'état de nos connaissances. Le modèle 0D a également permis d'étudier le bilan radicalaire dans ces trois environnements. Enfin, une comparaison des concentrations d'HONO mesurées et calculées pour les trois environnements a été menée, conduisant à l'identification d'une source additionnelle probablement de même nature dans les trois environnements étudiés / OH is the main oxidant of the troposphere during daytime hours. It is, thus, a key species for the complex atmospheric chemistry which involves other radical species and therefore leading to a radical cycle. This cycle is responsible for the transformation of the majority of the compounds emitted or formed in the atmosphere and thus of the formation of secondary pollutants, such as ozone and secondary organic aerosols which can have harmful effect on human health or important effects on climate. One of the main radical sources in the troposphere is the photolysis of nitrous acid. However, the intensity and the nature of the whole sources of HONO are still unknown.The aim of my thesis was, therefore, to study radical chemistry and nitrous acid chemistry in different environments in order to improve our understanding of oxidation processes occurring in the atmosphere. To answer to these objectives, this work was based on results obtained during field campaigns which took place in different environments and at different periods of year: the MEGAPOLI summer and winter campaign which took place in a suburban environments of Paris suburbs during the summer 2009 and the winter 2010 and finally the CalNEX campaign which took place in a polluted environment of the suburbs of Los Angeles during the spring 2010.Dealing with the results of these campaigns, a methodology consisting in the use of simple calculation such as the photostationnary state hypothesis or more complex approach such as a 0D box model containing a detailed chemical mechanism (the MCM) and being constrained with all the measurements, has been developed and compared with the measured radical concentrations in order to test our knowledge. The 0D box model, also, allowed studying the radical budget in these three environments. Finally, a comparison between the measured and calculated HONO concentrations for the three environments has been conducted. This comparison leads to the identification of an additional HONO source, which is probably of the same nature in the three environments

Hybrid motors that employ non-toxic, non-explosive components with a liquid oxidizer and a solid hydrocarbon fuel grain have inherently safe operating characteristics. The inherent safety of hybrid rocket motors offers the potential to greatly reduce overall operating costs. Another key advantage of hybrid rocket motors is the potential for in-flight shutdown, restart, and throttle by controlling the pressure drop between the oxidizer tank and the injector. This research designed, developed, and ground tested a closed-loop throttle controller for a hybrid rocket motor using nitrous oxide and hydroxyl-terminated polybutadiene as propellants. The research simultaneously developed closed-loop throttle algorithms and lab scale motor hardware to evaluate the fidelity of the throttle simulations and algorithms. Initial open-loop motor tests were performed to better classify system parameters and to validate motor performance values. Deep-throttle open-loop tests evaluated limits of stable thrust that can be achieved on the test hardware. Open-loop tests demonstrated the ability to throttle the motor to less than 10% of maximum thrust with little reduction in effective specific impulse and acoustical stability. Following the open-loop development, closed-loop, hardware-in-the-loop tests were performed. The closed-loop controller successfully tracked prescribed step and ramp command profiles with a high degree of fidelity. Steady-state accuracy was greatly improved over uncontrolled thrust.

The effect of global warming on methane (CH₄) and nitrous oxide (N₂O) emissions from agriculture was investigated and simulated from a soil warming experiment. Experiments were designed and installed in a temperature controlled greenhouse. The relationships between elevated temperatures and CH₄ and N₂O emissions were determined and calculated as the Q₁₀s of production, emission and oxidation. A study of the populations of methanogens and methanotrophs at a range of soil temperatures was performed based on soil molecular DNA analysis. This study showed that global warming would increase CH₄ emissions from rice agriculture and that the resultant emissions will be potentially large enough to cause changes in the present atmospheric concentrations. This research also showed that this increase was most evident for soil temperatures below 30⁰C, above which emissions decreased with increasing temperature. The seasonal average Q₁₀s of CH₄ emission, production, oxidation, methanogen and methanotroph populations were found to be 1.7, 2.6 and 2.2, 2.6 and 3.8, respectively, over a temperature of 20-32⁰C. Considering that the processes of CH₄ production and emission are similar to those in natural wetlands, which is the largest source of atmospheric CH₄, the contribution of this feedback is likely to cause a significant increase to the present CH₄ atmospheric budget if the current global warming trend persists over the next century. The Q₁₀s of N₂O emissions and production were 0.5-3.3 and 0.4-2.9, respectively. The low Q₁₀ values found for N₂O suggest that although global warming will have a direct impact on the production and emission rates. Nevertheless, the magnitude of the impact of global on both CH₄ and N₂O emissions from agriculture is likely to vary from one region to another due to the spatial variations in agricultural soil temperatures and the likely changes in the global regional distribution of water resources (water tables, rainfall patterns), water management practices and the responses of terrestrial CH₄ and N₂O sources such as natural wetlands and plants.

No description available.

Corn (Zea mays L.) and soybean (Glycine max (L.) Merr.) production in Illinois has a significant impact on the economy and environmental footprint in the state and the Midwest region. Nutrient leaching from Midwestern agricultural fields is one of the major reasons for the hypoxic zone developed in the Gulf of Mexico. Winter-fallow and early spring (after fertilizer application) are the two most critical periods for nutrient leaching due to increased precipitation and availability of nutrients. Cover crops (CCs) in these seasons are a promising best management practice (BMP) to reduce nutrient leaching in the winter-fallow season. No-till (NT) and reduced tillage (RT) are some other BMPs that farmers in Illinois adopt to reduce erosion. The adoption of CCs is limited due to the lack of knowledge and data on the yield and environmental benefits of CCs in different climatic and soil regimes. Thereby, this doctoral dissertation addresses several critical questions about CC and tillage impacts in claypan soils of southern Illinois with four principal projects with multiple objectives. Research study 1 was a field experiment conducted from 2013-to 2021 to understand the effect of CCs (CCs vs. noCC) and two tillage (NT and RT) practices on soil nitrate-N leaching. The experimental design was a complete randomized design with CC treatments that had two levels (two crop rotations) corn-cereal rye (Secale cereale L.)-soybean-hairy vetch (Vicia villosa R.) [CcrShv] and corn-noCC-soybean-noCC [CncSnc] and tillage treatments with two levels (NT and RT) replicated three times in the field. Each plot had a pan lysimeter installed below the A horizon (22-30 cm depth) to collect water samples weekly or biweekly depending on the rainfall. The corn yield was significantly greater in RT rotations compared to NT rotations with a 36% increase in the yield in 2019 and 2021 corn rotations. The yield was significantly greater in CcrShv rotations compared to the CncSnc rotations. The greatest yield was observed in the interaction of CcrShv-RT in all years. This increase in yield is inversely correlated to the remaining soil N values when the N credit from CCs was not accounted for. Soil nitrate-N leaching was significantly greater in CcrShv rotations compared to the CncSnc rotation in 2021 indicating vetch CC biomass decomposition can lead to increased leaching losses if the window between CC termination and corn planting is not minimized. Precipitation during the early spring can play a vital role in flushing the newly applied fertilizer as well as the N released from decomposing CC residue. The excessively wet year of 2019 showed that N losses are dominated by both nitrate-N leaching and nitrous oxide emissions, but in a typical growing season N losses are dominated by leaching compared to emissions. Research study 2 was designed to better understand the N cycling and fate of applied N in a complete corn-soybean rotation in southern Illinois with CCs and tillage practices. The research was overlayed in the same field with the same crop rotation and tillage practices. In this study, 15N labeled urea fertilizer (9.2% atom) was applied before the corn and soybean seasons. Soil, water, and biomass samples were collected to understand N distribution in each pool. In the corn season in 2017 a significantly greater 15N recovery was observed in CC (CcrShv) plots compared to the noCC plots in the sample collected seven days after planting (DAP). In the CC and depth interaction, a significantly greater 15N recovery was observed in 15-30 cm depth showing that the increased macropores due to CCs can lead to subsurface movement of N through the topsoil. The 15N recovery in water samples was high in CncSnc rotations in the cereal rye season but was significantly greater in CcrShv rotations (8.95 kg ha-1) in hairy vetch seasons. In the two years of complete rotation, the cumulative 15N recovery (quantity derived from fertilizer in water) was significantly greater in CC rotation. In the corn plants, the 15N recovered from the soil was greater than the 15N recovered from fertilizer. This shows the importance of the residual N from prior fertilizer and organic matter input. In the cereal rye season, CCs recovered significantly greater 15N from fertilizer compared to noCC rotations, assuring that cereal rye is an effective nutrient scavenger. A similar pattern was observed in the hairy vetch season as well. However, the soybean 15N recovery was greater in noCC rotations compared to CC rotations. The third study was a field trial on CCs and tillage to understand their individual and combined impact on soil physical parameters. Soil physical parameters were first measured in 2014 and were repeated in 2021. Bulk density at the 0-5 cm depth was 5% lower in 2021 compared to 2014 with the lowest BD in CC rotations with RT practices. For the depth of 0-15 cm, the lowest BD was observed in CC rotation with RT but, the largest reduction was observed in the CC rotation with NT. The wet aggregate stability was improved from 15-28 % over the years in all rotations. The lowest percentage improvement was observed in noCC rotation with RT practice. Penetration resistance was significantly lower in CC plots for the depth of 0-2.5 cm. CCs further improved the time to runoff in plots even though the infiltration rates were not affected. Chemical soil health indices were not significant overtime for CCs or tillage practices. However, a large number of earthworm counts were observed in NT systems compared to RT systems. The final project was a field trial to identify the soil P response to the CC and tillage practices. For this study, three different CC rotations, [corn-cereal rye-soybean-hairy vetch / corn-cereal rye-soybean-oats+radish / corn-noCC-soybean-noCC] and two tillage practices (NT and RT) were used. Soil samples were collected after the corn harvest in 2015 and 2021 and were analyzed for soil Phosphorus (P), inorganic P fractions by Chan and Jackson method, and dissolved reactive phosphorus (DRP) in leachate. The soil Mehlich-3 and Bray-1 P values indicate a great concentration of P in 0-15 cm depth for both years. More refined sampling in 2021 showed that the majority of P in 0-15 cm depth concentrates at the near-surface soil, in 0-5 cm depth irrespective of the CC and tillage treatment. Inorganic soil P fractions were not significantly different between CCs or tillage practices over time. Yet, irrespective of the treatment the non- labile P forms increased in 2021in the soil compared to 2015. The average and cumulative DRP values were highly dependent on the precipitation amounts and timing. However, in general, NT systems had greater average and cumulative DRP leaching compared to RT in both years. In general, CCs in the winter-fallow season is a good recommendation for farms that seek to maximize their production with a minimal environmental footprint. In the long run, CCs can improve soil physical and chemical properties which ultimately can increase the yield potential for corn and soybean. The added benefit of N credit due to leguminous CCs can reduce the fertilizer inputs. The CC benefits including the reduction in nutrient leaching depend on the type of CCs used in the field. More importantly, the CC termination time will be critical to obtain the maximum benefit of CCs. Even though the NT practices improve soil physical properties, long-term NT can increase the risk of soil P stratification in near-surface soils and can ultimately lead to more P loss via erosion, runoff, and soil water leaching. However, the combined use of CC and NT practices can help minimize the potential for erosion and runoff.