Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-09-05T17:18:06Z No. of bitstreams: 1 JANDUY GUERRA ARAÚJO - DISSERTAÇÃO PPGMet 2005..pdf: 3419275 bytes, checksum: cfc57ebb78334a2f29ed1f17e87ac1b7 (MD5) / Made available in DSpace on 2018-09-05T17:18:06Z (GMT). No. of bitstreams: 1 JANDUY GUERRA ARAÚJO - DISSERTAÇÃO PPGMet 2005..pdf: 3419275 bytes, checksum: cfc57ebb78334a2f29ed1f17e87ac1b7 (MD5) Previous issue date: 2005-05-30 / Capes / Neste trabalho, a fonte aparente de calor Q1 e o sumidouro aparente de umidade Q2 são investigados para anos de El Niño, de La Niña e anos normais. O objetivo é determinar o nível de máximo Q1 e Q2, as intensidades e a posição de Q1 em relação a Q2. Os dados utilizados são as reanálises do ECMWF e o estudo para cada episódio cobre o período de outubro a março. Inicialmente, são mostradas tabelas com o nível onde ocorre o máximo com base na média para cada mês de cada episódio estudado. As análises são para as regiões Amazônica e Nordeste do Brasil. Depois as intensidades de Q1 e de Q2 em dois níveis de referência são estudadas através de diagramas de Hovmöller ao longo da latitude de 5°S. Os resultados mostram que há uma diferença entre o Nordeste e a Amazônia, no que concerne ao nível de máximo Q1 e Q2 tanto espacial quanto também em relação às intensidades dessas grandezas. Além disso, houve relevantes diferenças entre os anos de El Niño e La Niña em ambas as regiões observadas. Especificamente os anos de La Niña se apresentaram com uma estrutura mais padronizada do nível de ocorrência de Q1 e de –Q2 enquanto que nos anos de El Niño se obteve mais níveis de ocorrência de máxima magnitude dessas entidades, o que evidencia uma estrutura mais desorganizada. Quanto à intensidade, a região tropical do Brasil admite valores de Q1 tão grandes quanto 50K/dia, do ponto de vista de um conjunto de dados com resolução horizontal de 2,5 graus. / In this work, we investigate both the apparent heat source Q1 and the apparent moisture sink Q2 for El Niño, La Niña and normal years. The aim is determining the level of maximum Q1 and Q2 and the intensity and position of Q1 in relation to Q2. Data used are the ECMWF reanalysis and the study spans the period from October through March for each episode. Initially we show tables containing the level where the maximum occurs based on monthly averages for each episode. The analyses are focused on Amazonia and Northeast Brazil. In the sequence, we investigate the intensities of both Q1 and Q2 for two reference levels through Hovmöller diagrams along the 5°S latitude. The results show differences between Northeast Brazil and Amazônia when the level of occurrence of the maximum, the space location and the intensity of both Q1 and Q2 are concerned. Moreover there are substantial event-to-event differences for both regions. La Niña years show a more organized structure in terms of the level of occurrence of Q1 and Q2. On the other hand, El Niño years show a more disorganized structure. Finally, we found that from the viewpoint of a data set with horizontal resolution of 2.5 degree, tropical Brazil admits values of Q1 as large as 50K/day.

The scope of this Master´s thesis is estimation of changing of heat source in a heating plant 2.5 MW. In the present heating plant burns natural gas, placing of the heating plant makes it possible development source of burning biomass. The scope of thesis is establish with regard to developed capital and operational costs, next effects to environment in scene of heat source, measuring and regulation of technological unit, determination of acceptable size of fuel depot and composition of fuel and ashes economy. The results of this Master´s thesis can be used as a basis about determination toward investment.

The aim of the thesis is to select a suitable heat source for a residential building using simulation modeling and multiple-criteria decision analysis. The market is offering plenty of possibilities, thus the part of this thesis is dedicated to description of main characteristics and pros and cons of most common heat sources (e.g. coal, biomass, natural gas, electricity, heat pumps). There are many ways to decide which source is an optimal solution for a house. In this thesis, there are presented four possible approaches: decision based on the analysis of the total costs of the source and the methods WSA, TOPSIS and ELECTRE III. In the end, the results of these methods are summarized together with the qualitative factors which are also considered in the decision making process.

This diploma thesis deals with comparison of possible ways to supply the specific house by thermal energy. In the first part is a brief introduction of the building and determination of heat consumption. Following chapters are devoted to description and sorting of gas boilers, heat pumps, biomass boilers and solar collectors, inclusive the choice of specific source of heat. In the following part is stated economic evaluation of selected heat sources. Final part of the thesis is focused on design of additional exchanger instead of gas boiler.

The aim of the diploma thesis "The use of alternative fuels in heating buildings " is the application of the heat sources using alternative fuels for heating of the production hall. The source of heat is a gas boiler, wood chips and dark gas infrared heaters. Appliances are then convection heaters, tubular registers and hot-air units.

The diploma thesis is consists from three main parts. In the first section are stated heating options in the apartment building. The second part deals with calculations of heat loss. A third part presents an economic assessment of the various options.

The thesis is focused on the design of the new heat source of the existing building. The first part deals with the heat sources and fuels used in the Czech Republic. The second part includes design of three variants of heat sources: gas boilers, cogeneration unit with the electric boilers and cogeneration unit with gas boilers. The individual variations are also evaluated in terms of user comfort, space requirements or economy of operation. The third part includes measurement and evaluation of internal environment of the dining hall.

Laser welding is an advanced joining technique with the capability to form deep, narrow, and precise welds. Numerical models are used to simulate the process in attempts of predicting distortions and stresses in the material. This is done to reduce physical testing, optimize processes and enable integrated product- and process development. The Virtual Manufacturing Process research group at University of Skövde wishes to increase their knowledge on modeling options of thermomechanical simulations to grant local industries these benefits. A numerical model for the laser welding process was developed in ABAQUS. This was done by examining the macrograph structure of a simple weld and applied to a stainless-steel T-joint welding application. The macrograph data was used to calibrate a mathematical heat source model. User subroutine DFLUX was used to enable movement of the heat source and element activation was used to simulate the fusion of the two parts. A T-joint welding experiment was carried out to measure deflection and the result was compared to numerical simulations. Different combinations of heat source models, coupling type and element activation was compared in relation to predicting the deflection. Computational time and modeling complexity for the techniques was also considered.The results showed that a 3D Gaussian heat source model will imitate the keyhole weld achieved superior to the compared 2D model. The 3D model provides greater flexibility since it enables combinations of any geometrical bodies. It was shown that element activation has a significant contribution on part stiffness and thus resulting distortions. To implement element activation a fully coupled analysis is required. The deflection of the fully coupled 3D simulation with element activation showed a 9% deviance in deflection compared with experiments.

Continuous welding is one of the prominent techniques used in producing seamless piping used in many applications such as the mining and the oil and gas industries. Weld defects cause significant loss of time and money in the piping production industry. Therefore, there is a need for effective online weld defects detection systems. A laser-based weld defects detection (LBWDD) system has been developed by the industrial partner. However, the current LBWDD system can only detect some geometrically based weld defects, but not material inhomogeneity such as voids, impurities, inclusions, etc. The main objective of this study is to assess the predictability of a thermal imaging-based weld defects detection system (TIBWDD) using an IR camera that can be integrated with the current LBWDD system. The aim of the integrated detection system is to be able to detect a wider range of weld defects. A test rig has been designed and used to carry out a set of emissivity (ε) calculation experiments considering three different materials – Aluminum 5154 (Al), Stainless Steel 304L (SS), and Low Carbon Steel A131 (LCS) with two surface finishes 0.25 μm (FM) and 2.5 μm (RM), which are relevant to pipe welding operations. Al showed least change in ε varying from 0.162 to 0.172 for FM samples and from 0.225 to 0.250 for RM samples from 50°C to 550°C. LCS showed highest change in ε varying from 0.257 – 0.918 for FM samples and from 0.292 to 0.948 for RM samples. SS showed a consistent increase in ε for both FM and RM samples. Experimental and numerical analysis have been carried out mimicking two sets of possible weld defects investigating defect size, Dh, and distance between effect and sample surface, δ. Results showed that the δ based defects that are located within 3 mm can be detected by the IR camera. Defects with Dh = 1. 5 mm can be detected by the IR camera with and without glass wool. Laser welding simulations using 2D and 3D Gaussian heat source models have been carried out to assess the predictability of a set of possible weld defects. The heat source models have been validated using experimental data. Three sets of defects were considered representing material-based inhomogeneity, step and inclined misalignment defects. For material-based inhomogeneity in thin plates all defects located at 1.25 mm from the surface are found detectable as ΔT (temperature difference obtained on surface) > ΔTmin (detectability limit of TIBWDD system). For inhomogeneity defects in thick plates, except defects of 2.5 mm in square size all other defects were found detectable as ΔT > ΔTmin. All step misalignment defects were detected for thin and thick plates. In the case of inclined misalignment defects, for thin plates, the misalignment error in the thin plate had to be at least 0.275 mm to be detected. In the case of thick plates, the misalignment error had be at least 0.375 mm to be detected. Overall, results of the present study confirm that thermal imaging can be successfully used in detecting material-based and geometry-based weld defects. / Thesis / Master of Applied Science (MASc)

No description available.