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An investigation has been carried out into the twist blockage which may occur when yarns pass over guides or other surfaces. The influence of primary physical parameters such as surface curvature, are and length of contact, yarn twist level and tension and yarn/surface friction have been investigated together with secondary parameters such as yarn surface, pressure, angle of approach etc. As a result of these investigations, three mechanisms of blockage have been identified. The first of these occurs especially with doubled yarn in which the components lie side by side on the guide surface and blocked twist builds up until sufficient torque is developed to turn the yarn over against the couple generated by the components of yarn tension and reaction on the guide surface. In the second mechanism blocking torque is generated by components of friction on the yarn surface at right angles to the yarn axis. These orthogonal friction components may arise from interaction between the topography of the twisted yarn surface and the guide surface or may be generated by forces arising from an angular orientation of yarn to guide. The third mechanism is intermediate between the other two where a singles yarn (or its equivalent) is flattened on the surface and resistance to twist transmission is generated partly by internal friction within the yarn and partly by yarn/guide frictional forces. The main circumstances under which these different mechanisms may operate, have been identified and suggestions made for minimising the blockage of twist.

The presence of a blockage in a pipeline will alter the fluid dynamics of a flowing system in terms of the heat, mass and velocity characteristics. The analysis of the fluid dynamics is based on balances taken on the overall system to qualitatively and quantitatively assess the effects of the blockage. Pioneer work in the area of mass and momentum effects of blockages led to the development of blockage type curves useful in characterizing blockages from limited information. This work is an extension of previous work and is based on the application of a simplistic energy balance approach to characterize blockages in pipelines. The resulting heat models for the case of both a partially and fully-blocked flowline correctly predict the effect of wax deposition. Dimensionless temperature-based blockage maps developed here can be used in modeling unique cases where only two of the three necessary conditions are given. The heat model matches results from commercial software within a limited range of restricted flow conditions.

The primary purpose of this research was to improve the accuracy and robustness of pipeline transient modeling. An algorithm was developed to model the transient flow in closed tubes for thin walled pipelines. Emphasis was given to the application of this type of flow to pipelines with small radius 90° elbows. An additional loss term was developed to account for the presence of 90° elbows in a pipeline. The algorithm was integrated into an optimization routine to fit results from the improved model to experimental data. A web based interface was developed to facilitate the pre- and post- processing operations. Results showed that including a loss term that represents the effects of 90° elbows in the Method of Characteristics (MOC) [1] improves the accuracy of the predicted transients by an order of magnitude. Secondary objectives of pump optimization, blockage detection and removal were investigated with promising results.

This work aims to assess human nasal blockage by investigating its influence on nasal airflow dynamics, both computationally and experimentally. An in-house CFD code (Lithium) computes the steady (mean) nasal airflow for a cavity constructed from CT images of a healthy adult, for the internal cavity and for the first time for the external flow. To account for turbulence occurrence, the low Reynolds number k-ω Reynolds-Averaged-Navier-Stokes (RANS) model is used. The flow field is calculated at different breathing rates by varying the influx rate. Blockages are introduced at various locations inside the cavity to investigate common nasal blockages. The computational results are assessed against published literature and the Particle Image Velocimetry experimental (PIV) results, carried out on a 2.54:1 scale model of the computational nasal cavity. Schlieren optical technique is also used for external nasal airflow visualizations of a human subject, to comment on using an optical system for clinical application. These computations reveal a significant dependency of both, the internal and external nasal airflow fields on the nasal cavity’s geometry. Although for this model, the flow is found to be turbulent in the inspiratory phase of 200 ml/s and higher, it is suggested that the nature of flow can vary depending on the nasal cavity’s structure which is influenced by genetics. Nevertheless, some common flow features were revealed such as higher flow rate in the olfactory region and main flow passage through lower airways during inspiration. More uniform flow passage was found in expiration. The results also suggest a possible correlation between the internal geometry of the cavity and the external nasal airflow angle and thickness. This correlation can allow an application of optical systems such as Schlieren which is shown to give accurate qualitative images of the external nasal airflow for assessment of the nasal blockage.

The influence of effluent addition on denitrification potential in the Thredbo Wetland was observed by comparing an area of the wetland receiving secondary treated effluent with another area receiving no effluent addition. Physico-chemical measurements (Eh, pH and temperature) of the soil were conducted in both sampling areas to characterise the denitrifying environment. Levels of nitrate plus nitrite and ammonium ion in the soil from 0-30cm depth were recorded on a seasonal basis to identify the role of effluent addition and vertical distribution of inorganic nitrogen species in controlling the distribution of denitrification potential in the soil. Denitrification potentials of soils and decaying plant material were evaluated by the acetylene blockage technique. This involved laboratory incubations under optimum conditions of pH, temperature, nitrate concentration, carbon supply, and diffusion. The influence of these physico-chemical factors on denitrification was also investigated. It was found that the effluent addition caused higher denitrification potential in soils and surface decaying plant material by raising soil temperature, lowering Eh, and increasing concentrations of nitrate plus nitrite and ammonium ions. The highest denitrification potential was recorded in the decaying plant material on the soil surface. The highest soil denitrification potential occurred in the 0-6cm depth segment. Carbon supply and pH had no influence on denitrification potential whilst low temperature (5ºC), and restricted diffusion limited denitrification. In terms of tertiary water treatment denitrification in Thredbo Wetland makes a significant-contribution to the removal of nitrogen year-round. However, total nitrogen removal could be increased by increasing the residence time of water in the wetland thereby encouraging greater spatial and temporal interaction between the denitrifiers and the wastewater nitrogen.

京都大学 / 0048 / 新制・論文博士 / 博士(工学) / 乙第12950号 / 論工博第4126号 / 新制||工||1628(附属図書館) / 32249 / 京都大学大学院工学研究科化学工学専攻 / (主査)教授 長谷部 伸治, 教授 前 一廣, 教授 吉田 潤一 / 学位規則第4条第2項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Yes / Event monitoring is an essential application of Smart City platforms. Real-time monitoring of gully and drainage blockage is an important part of flood monitoring applications. Building viable IoT sensors for detecting blockage is a complex task due to the limitations of deploying such sensors in situ. Image classification with deep learning is a potential alternative solution. However, there are no image datasets of gullies and drainages. We were faced with such challenges as part of developing a flood monitoring application in a European Union-funded project. To address these issues, we propose a novel image classification approach based on deep learning with an IoT-enabled camera to monitor gullies and drainages. This approach utilises deep learning to develop an effective image classification model to classify blockage images into different class labels based on the severity. In order to handle the complexity of video-based images, and subsequent poor classification accuracy of the model, we have carried out experiments with the removal of image edges by applying image cropping. The process of cropping in our proposed experimentation is aimed to concentrate only on the regions of interest within images, hence leaving out some proportion of image edges. An image dataset from crowd-sourced publicly accessible images has been curated to train and test the proposed model. For validation, model accuracies were compared considering model with and without image cropping. The cropping-based image classification showed improvement in the classification accuracy. This paper outlines the lessons from our experimentation that have a wider impact on many similar use cases involving IoT-based cameras as part of smart city event monitoring platforms. / European Regional Development Fund Interreg project Smart Cities and Open Data REuse (SCORE).

Wind tunnel experiments will continue to be a primary source of validation data for many types of mathematical and computational models in the aerospace industry. The increased emphasis on accuracy of data acquired from these facilities requires understanding of the uncertainty of not only the measurement data but also any correction applied to the data. One of the largest and most critical corrections made to these data is due to wall interference. In an effort to understand the accuracy and suitability of these corrections, a statistical validation process for wall interference correction methods has been developed. This process is based on the use of independent cases which, after correction, are expected to produce the same result. Comparison of these independent cases with respect to the uncertainty in the correction process establishes a domain of applicability based on the capability of the method to provide reasonable corrections with respect to customer accuracy requirements. The statistical validation method was applied to the version of the Transonic Wall Interference Correction System (TWICS) recently implemented in the National Transonic Facility at NASA Langley Research Center. The TWICS code generates corrections for solid and slotted wall interference in the model pitch plane based on boundary pressure measurements. Before validation could be performed on this method, it was necessary to calibrate the ventilated wall boundary condition parameters. Discrimination comparisons are used to determine the most representative of three linear boundary condition models which have historically been used to represent longitudinally slotted test section walls. Of the three linear boundary condition models implemented for ventilated walls, the general slotted wall model was the most representative of the data. The TWICS code using the calibrated general slotted wall model was found to be valid to within the process uncertainty for test section Mach numbers less than or equal to 0.60. The scatter among the mean corrected results of the bodies of revolution validation cases was within one count of drag on a typical transport aircraft configuration for Mach numbers at or below 0.80 and two counts of drag for Mach numbers at or below 0.90. / Ph. D.

A computer model of a blow-down free-jet hypersonic propulsion test facility exists to validate facility control systems as well as predict problems with facility operation. One weakness in this computer model is the modeling of an air ejector diffuser system. Two examples of facilities that could use this ejector diffuser model are NASA Langley Research Center's 8-ft High Temp. Tunnel (HTT) and the Aero-Propulsion Test Unit (APTU) located at Arnold Engineering Development Center. Modeling an air ejector diffuser system for a hypersonic propulsion test facility includes modeling three coupled systems. These are the ejector system, the primary free-jet nozzle that entrains secondary airflow from the test cell, and the test article. Both of these facilities are capable of testing scramjets/ramjets at high Mach numbers. Compared with computer simulation data, experimental test cell pressure data do not agree due to the current modeling technique used. An improved computer model was derived that incorporates new techniques for modeling the ejector diffuser. This includes real gas effects at the ejector nozzles, flow constriction due to free-jet nozzle and ejector plumes, test article effects, and a correction factor of the normal shock pressure ratio in a supersonic diffuser. A method was developed to account for the drag and thrust terms of the test article by assuming a blockage factor and using a drag coefficient*Area term for both the test article and thrust stand derived from experimental data. An ideal ramjet model was also incorporated to account for the gross thrust of the test article on the system. The new ejector diffuser model developed improved the accuracy and fidelity of the facility model as compared with experimental test data while only negligibly affecting computational speed. Comparisons of the model data with experimental test data showed a close match for test cell pressure (within 1 percent for final test cell pressure). The model accurately simulated both the unstarted and started modes of ejector flow, in which test cell pressure increases with nozzle total pressure once in started mode.