Orientador: Milton Mori / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-07-19T19:54:05Z (GMT). No. of bitstreams: 1 Souza_DanielRolladeCamargo_M.pdf: 4662537 bytes, checksum: bae865916334a6c7d4b5c87e4c2474af (MD5) Previous issue date: 1994 / Resumo: O presente trabalho teve como objetivo a construção de um programa que calcula a eficiência de coleta e a perda de carga apresentada por um ciclone sob determinadas condições de operação. A criação deste programa foi solicitada pela PETROBRÁS-SIX (Superintendência da Industrialização do Xisto), unidade de São Mateus do Sul (PR), devido ao seu interesse em dispor desse tipo de ferramenta para simulação e/ou projeto de ciclones. O programa dispõe de oito métodos diferentes para cálculo de eficiência e sete métodos para cálculo de queda de pressão, sendo todos eles empíricos ou semi-empíricos. A fim de possibilitar a avaliação do grau de exatidão dos resultados obtidos por cada um desses métodos, foi construído, ainda, um banco de dados contendo 108 arquivos de dados experimentais. Destes, 80 correspondem a dados obtidos da literatura e 28, aos dados gerados por uma série de testes realizados em uma unidade de bancada na própria SIX. A partir destes dados foi feita uma análise da performance de cada um dos métodos existentes no programa construído / Abstract: The goal of this work was to develop a software which calculates the collection efficiency and pressure drop observed in a cyclone under known operational conditions. The creation of this software was solicited by the São Mateus do Sul (PR) unit of PETROBRÁS-SIX, due to its interest in having this kind of tool for the cyclone design and/or simulation. The software has eight different methods for the prediction of efficiency, and seven methods oriented for pressure drop calculations. Ali of them are empiric or semi-empiric. In order to evaluate the accuracy achieved by each method, a data bank containing 108 files with experimental results was constructed: 80 files were obtained from the literature and the other 28 files were generated by a set of tests carried out in a test system at PETROBRÁS-SIX. These data were used to analyse the performance of each method present in the developed software / Mestrado / Sistemas de Processos Quimicos / Mestre em Engenharia Química

Semi-conductor industry relies heavily on silicon (Si). However, Si is not a direct-band gap semi-conductor. Consequently, Si does not possess great versatility for multi-functional applications in comparison with the direct band-gap III-V semi-conductors such as GaAs. To bridge this gap, what is ideally required is a semi-conductor material system that is based on silicon, but has significantly greater versatility. While sparsely studied, the semi-conducting silicides material systems offer great potential. Thus, I focused on the growth and structural characterization of ruthenium silicide and osmium silicide material systems. I also characterized iron silicon germanide films using extended x-ray absorption fine structure (EXAFS) to reveal phase, semi-conducting behavior, and to calculate nearest neighbor distances. The choice of these silicides material systems was due to their theoretically predicted and/or experimentally reported direct band gaps. However, the challenge was the existence of more than one stable phase/stoichiometric ratio of these materials. In order to possess the greatest control over the growth process, molecular beam epitaxy (MBE) has been employed. Structural and film quality comparisons of as-grown versus annealed films of ruthenium silicide are presented. Structural characterization and film quality of MBE grown ruthenium silicide and osmium silicide films via in situ and ex situ techniques have been done using reflection high energy electron diffraction, scanning tunneling microscopy, atomic force microscopy, cross-sectional scanning electron microscopy, x-ray photoelectron spectroscopy, and micro Raman spectroscopy. This is the first attempt, to the best of our knowledge, to grow osmium silicide thin films on Si(100) via the template method and compare it with the regular MBE growth method. The pros and cons of using the MBE template method for osmium silicide growth are discussed, as well as the structural differences of the as-grown versus annealed films. Future perspectives include further studies on other semi-conducting silicides material systems in terms of growth optimization and characterization.

Rainfall in semi-arid areas is generally insufficient to meet crop water requirements, and above all erratic in distribution. This leads to crop yield fluctuation, which drastically affects food security. Rainwater harvesting technologies have been implemented in these areas in order to mitigate the effect of perennial droughts. The successful adoption of these technologies can contribute to poverty alleviation, and therefore improve the livelihood of resource-poor subsistence farmers. Field trials for testing different rainwater harvesting scenarios are expensive, time consuming and laborious. As a result, crop models must be used to help study these systems, and thereby make prudent water harvesting design choices for specific situations. For this purpose, a simple, one-dimensional soil water balance model (Soil Water Balance-SWB) was modified by incorporating linear runoff estimation models in order to predict the soil water balance and crop yield under different rainwater harvesting design scenarios and to select the design most likely to succeed in a particular locality. Field data collected during the 2007/2008 maize growing season, on sandy clay loam soils, at the Hatfield Experimental Farm of the University of Pretoria, was used to parameterize the different runoff models and to calibrate the SWB crop model. Various rainwater harvesting design scenarios were run for two different semi-arid areas, on different soil types to illustrate the application of the SWB model as a tool to help design the most appropriate rainwater harvesting strategy, taking into account whether arable land is limiting or not limiting for crop production. The SWB model was successfully calibrated. Simulation results reveal that in drier years bigger design ratios (cropping area: runoff area) of the in-field rainwater harvesting technique (IRWH) are most likely to be successful, while in wetter years smaller design ratios of the IRWH technique or even simpler rainwater harvesting strategies such as the tied ridge and the conventional tillage techniques can harvest sufficient rainfall for maximum crop production. Results from field trials conducted in Pretoria, on sandy clay loam soils, confirmed that, in a wet season, maize yield is maximized by a smaller IRWH design (1:1B). The SWB model can be used as a tool to help selecting the most appropriate rainwater harvesting strategy under specific conditions with minimum input requirements. / Dissertation (MSc)--University of Pretoria, 2011. / Plant Production and Soil Science / unrestricted

A well-known challenge in vehicle dynamics is to design a vehicle that will not only keep the occupants comfortable, but will also ensure safe and stable operation during various manoeuvres over multiple driving surfaces. A soft and compliant suspension is generally required for good ride comfort, while a stiff suspension with a low centre of mass is required for improved handling. These contradicting factors in the design process is commonly referred to as the ride comfort versus handling compromise. A newly developed semi-active hydropneumatic suspension system is proposed to reduce or negate this compromise by being able to change its characteristics according to the dynamic state of the vehicle. The unit is equipped with two proportional solenoid valves that can provide continuously variable damping. In addition, the valves are able to completely close off flow to compressible gas volumes to provide four discrete stiffness characteristics. This suspension system is based on a previously developed suspension that had only two state (open or closed) valves, which provided discrete damping characteristics. A thorough investigation of the older system proved that the system was capable of addressing the ride comfort versus handling compromise. The purpose of this study was to investigate whether the updated design could deliver improved performance and to recommend focus areas for future research initiatives. The suspension system’s characteristics were determined experimentally by actuating the unit on a test bench. Results indicated that the unit produced the desired stiffness, low damping and response time characteristics. A mathematical model of the suspension unit was developed and validated against experimental data. The model was used in single degree of freedom simulations to investigate both passive and semi-active controlled performance. Results indicated that the suspension could be semi-actively controlled for improve ride comfort. However, the magnitude of improvements with semi-active control, which includes a suitable response time, proved to be rather insignificant compared to the optimum passive suspension. / Dissertation (MEng)--University of Pretora, 2019. / Mechanical and Aeronautical Engineering / MEng (Mechanical) / Unrestricted

NR 20140805

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / This work proposes the design of a low cost semi-industrial three degree of freedom CNC vertical milling center (VMC) with non-ferrous metal machining capabilities. The design seeks to mitigate the difficulties that acquiring a commercial industrial CNC can present, such as large dimensions, high cost and complications in its transportation within the plant. The proposed machine will be made up of 1 NEMA 23 stepper motor for each X, Y and Z axis, and will be controlled by open source firmware using an ATMEGA 2560 microcontroller. Likewise, the working area will be 320x180mm and will have a precision 100 microns with semi industrial capacities. This design is aimed at small and medium-sized companies that are looking for a low cost non-ferrous CNC milling machine that in turn has the quality, performance and precision of an industrial one.

Supervised deep neural networks have been successfully applied to many real-world measurement applications. However, their success relies on labeled data which is expensive and time-consuming to obtain, especially when domain expertise is required. For this reason, researchers have turned to semi-supervised learning for image classification tasks. Semi-supervised learning uses structural assumptions to automatically leverage unlabeled data, dramatically reducing manual labeling efforts. We conduct our research based on images from Enclosures Direct Inc. (EDI) which is a manufacturer of enclosures used to house and protect electronic devices. Their industrial robotics utilizes a computer vision system to guide a robot in a welding application employing a laser and a camera. The laser is combined with an optical line generator to cast a line of structured light across a joint to be welded. An image of the structured light is captured by the camera which needs to be located in the image in order to find the desired coordinate for the weld seam. The existing system failed due to the fact that the traditional machine vision algorithm cannot analyze the image correctly in unexpected imaging conditions or during variations in the manufacturing process. In this thesis, we purpose a novel algorithm for semi-supervised key-point detection for seam placement by a welding robot. Our deep learning based algorithm overcomes unfavorable imaging conditions providing faster and more precise predictions. Moreover, we demonstrate that our approach can work with as few as ten labeled images accepting a reduction of detection accuracy. In addition, we also purpose a method that can utilize full image resolution to enhance the accuracy of the key-point detection.

Throughout midwestern North American ecosystems, semi-aquatic mammals including beaver (Castor canadensis), mink (Neovision vision), muskrat (Ondatra zibethicus), and river otter (Lontra canadensis) co-exist in wetlands. These species are ecologically important through their manipulation of habitats and interactions with other species present. The Lake County Forest Preserve District (Lake County, Illinois) is actively restoring forest preserves using several restoration practices and are interested in how these efforts may affect semi-aquatic mammal occupancy. We studied impacts of restoration practices and other environmental covariates on detection and occupancy of the 4 aforementioned focal species. Sign surveys were conducted during December-April in 2018-19 and 2019-20. Single species, multi-season models were run in RStudio using the package unmarked. Muskrat detection (p̂ = 0.60 ± 0.03) was positively affected by survey replicate, and negatively impacted by last precipitation amount and bank angle. Beaver detection (p̂ = 0.76 ± 0.03) was positively affected by survey replicate and previous 2-week precipitation amount, and negatively influenced by bank angle. Mink detection (p̂ = 0.26 ± 0.04) was positively impacted by survey replicate, and negatively affected by last precipitation amount and previous 2-week precipitation amount. River otter detection (p̂ = 0.10 ± 0.07) was not influenced by any covariates sampled. Muskrat had the highest occupancy (ψ ̂= 0.90 ± 0.05), followed by beaver (ψ ̂ = 0.57 ± 0.07), mink (ψ ̂ = 0.57 ± 0.10), and river otter (ψ ̂ = 0.28 ± 0.18). Both muskrat and river otter occupancy were not affected by any covariates sampled. Beaver occupancy was positively impacted by stream density and number of saplings. Mink occupancy was positively affected by stream density. No focal species’ occupancies were influenced by restoration practices. From these findings, I provide recommendations for future surveys and management for semi-aquatic furbearers in urban landscapes. Thank you to the Lake County Forest Preserve District for funding my research.

This thesis presents a novel singular-value-based semi-fragile watermarking scheme for image content authentication with tampering localization. The proposed scheme first generates a secured watermark bit sequence by performing a logical "xor" operation on a content-based watermark and content-independent watermark, wherein the content-based watermark is generated by a singular-value-based watermark bit sequence that represents intrinsic algebraic image properties, and the content-independent watermark is generated by a private-key-based random watermark bit sequence. It next embeds the secure watermark in the approximation subband of each non-overlapping 4×4 block using the adaptive quantization method to generate the watermarked image. The image content authentication process starts with regenerating the secured watermark bit sequence following the same process mentioned in the secured watermark bit sequence generation. It then extracts a possibly embedded watermark using the parity of the quantization results from the probe image. Next, the authentication process constructs a binary error map, whose height and width are a quarter of those of the original image, using the absolute difference between the regenerated secured watermark and the extracted watermark. It finally computes two authentication measures (i.e., M1 and M2), with M1 measuring the overall similarity between the regenerated watermark and the extracted watermark, and M2 measuring the overall clustering level of the tampered error pixels. These two authentication measures are further seamlessly integrated in the authentication process to confirm the image content and localize any possible tampered areas. The extensive experimental results show that the proposed scheme outperforms four peer schemes and is capable of identifying intentional tampering, incidental modification, and localizing tampered regions.

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.