This thesis presents cutter swept volume generation, in-process workpiece modeling and Cutter Workpiece Engagement (CWE) algorithms for finding the instantaneous intersections between cutter and workpiece in milling. One of the steps in simulating machining operations is the accurate extraction of the intersection geometry between cutter and workpiece. This geometry is a key input to force calculations and feed rate scheduling in milling. Given that industrial machined components can have highly complex geometries, extracting intersections accurately and efficiently is challenging. Three main steps are needed to obtain the intersection geometry between cutter and workpiece. These are the Swept volume generation, in-process workpiece modeling and CWE extraction respectively. In this thesis an analytical methodology for determining the shapes of the cutter swept envelopes is developed. In this methodology, cutter surfaces performing 5-axis tool motions are decomposed into a set of characteristic circles. For obtaining these circles a concept of two-parameter-family of spheres is introduced. Considering relationships among the circles the swept envelopes are defined analytically. The implementation of methodology is simple, especially when the cutter geometries are represented by pipe surfaces. During the machining simulation the workpiece update is required to keep track of the material removal process. Several choices for workpiece updates exist. These are the solid, facetted and vector model based methodologies. For updating the workpiece surfaces represented by the solid or faceted models third party software can be used. In this thesis multi-axis milling update methodologies are developed for workpieces defined by discrete vectors with different orientations. For simplifying the intersection calculations between discrete vectors and the tool envelope the properties of canal surfaces are utilized. A typical NC cutter has different surfaces with varying geometries and during the material removal process restricted regions of these surfaces are eligible to contact the in-process workpiece. In this thesis these regions are analyzed with respect to different tool motions. Later using the results from these analyses the solid, polyhedral and vector based CWE methodologies are developed for a range of different types of cutters and multi-axis tool motions. The workpiece surfaces cover a wide range of surface geometries including sculptured surfaces.

This thesis presents cutter swept volume generation, in-process workpiece modeling and Cutter Workpiece Engagement (CWE) algorithms for finding the instantaneous intersections between cutter and workpiece in milling. One of the steps in simulating machining operations is the accurate extraction of the intersection geometry between cutter and workpiece. This geometry is a key input to force calculations and feed rate scheduling in milling. Given that industrial machined components can have highly complex geometries, extracting intersections accurately and efficiently is challenging. Three main steps are needed to obtain the intersection geometry between cutter and workpiece. These are the Swept volume generation, in-process workpiece modeling and CWE extraction respectively. In this thesis an analytical methodology for determining the shapes of the cutter swept envelopes is developed. In this methodology, cutter surfaces performing 5-axis tool motions are decomposed into a set of characteristic circles. For obtaining these circles a concept of two-parameter-family of spheres is introduced. Considering relationships among the circles the swept envelopes are defined analytically. The implementation of methodology is simple, especially when the cutter geometries are represented by pipe surfaces. During the machining simulation the workpiece update is required to keep track of the material removal process. Several choices for workpiece updates exist. These are the solid, facetted and vector model based methodologies. For updating the workpiece surfaces represented by the solid or faceted models third party software can be used. In this thesis multi-axis milling update methodologies are developed for workpieces defined by discrete vectors with different orientations. For simplifying the intersection calculations between discrete vectors and the tool envelope the properties of canal surfaces are utilized. A typical NC cutter has different surfaces with varying geometries and during the material removal process restricted regions of these surfaces are eligible to contact the in-process workpiece. In this thesis these regions are analyzed with respect to different tool motions. Later using the results from these analyses the solid, polyhedral and vector based CWE methodologies are developed for a range of different types of cutters and multi-axis tool motions. The workpiece surfaces cover a wide range of surface geometries including sculptured surfaces.

This thesis presents cutter swept volume generation, in-process workpiece modeling and Cutter Workpiece Engagement (CWE) algorithms for finding the instantaneous intersections between cutter and workpiece in milling. One of the steps in simulating machining operations is the accurate extraction of the intersection geometry between cutter and workpiece. This geometry is a key input to force calculations and feed rate scheduling in milling. Given that industrial machined components can have highly complex geometries, extracting intersections accurately and efficiently is challenging. Three main steps are needed to obtain the intersection geometry between cutter and workpiece. These are the Swept volume generation, in-process workpiece modeling and CWE extraction respectively. In this thesis an analytical methodology for determining the shapes of the cutter swept envelopes is developed. In this methodology, cutter surfaces performing 5-axis tool motions are decomposed into a set of characteristic circles. For obtaining these circles a concept of two-parameter-family of spheres is introduced. Considering relationships among the circles the swept envelopes are defined analytically. The implementation of methodology is simple, especially when the cutter geometries are represented by pipe surfaces. During the machining simulation the workpiece update is required to keep track of the material removal process. Several choices for workpiece updates exist. These are the solid, facetted and vector model based methodologies. For updating the workpiece surfaces represented by the solid or faceted models third party software can be used. In this thesis multi-axis milling update methodologies are developed for workpieces defined by discrete vectors with different orientations. For simplifying the intersection calculations between discrete vectors and the tool envelope the properties of canal surfaces are utilized. A typical NC cutter has different surfaces with varying geometries and during the material removal process restricted regions of these surfaces are eligible to contact the in-process workpiece. In this thesis these regions are analyzed with respect to different tool motions. Later using the results from these analyses the solid, polyhedral and vector based CWE methodologies are developed for a range of different types of cutters and multi-axis tool motions. The workpiece surfaces cover a wide range of surface geometries including sculptured surfaces. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

This work deal with different variants of the turning milling heads for CNC machines.The report depicts actual design solution of the turning milling head formilling machine, including technical report and economical conclusions.

The dredging activity is increasing worldwide due to ships that require bigger drafts, and consequently deeper navigation channels. Some dredging projects requires the operation of cutter suction dredgers on open waters, once these are capable of removing compact sediments and rocks while still maintaining a good productivity. These facts motivated the creation of a weather driven downtime prediction software for this type of operation, based on simplified calculations of the main dredging systems of a CSD. The motions caused by waves, and the forces and moments caused on these dredgers by winds, waves and currents were analyzed in order to evaluate the influence of each parameter magnitude and direction on the behavior of the vessel. The main criteria of the dredger influenced by this conditions were determined by a literature review as being the swing winch required power, the interaction between the cutterhead and the soil, and the anchoring system resistance, this that can be both a spud pole system stress or the Christmas tree cable tension. In this research, only the spud pole system bending stress was considered. Three mathematical models were developed to represent those systems. Since the non-linearity of the relation between the reaction forces of the dredger and the soil was not an object of the study, this process is represented by a constant user defined reaction force and a horizontal cutterhead velocity model. The efficiency of these models were tested by applying them on a case study of the dredging of the Açu port on the Brazilian coast by the Taurus II dredger. Simultaneous wind, wave and current data data were used as input to these models by creating a time series scenario of the operation period. The results for both scenarios showed that the operation would be close to impossible due to wave generated dynamic stress on the spud pole. / A atividade de dragagem no mundo é cada vez mais significativa em função do aumento dos navios que operam em portos, estes que possuem maior calado e requerem, consequentemente, canais de navegação mais profundos. Alguns projetos de dragagem utilizam dragas de sucção e recalque em mar aberto, dada a capacidade destes equipamentos de remover sedimento compactado e rochas, ainda mantendo uma boa produtividade. Estes fatos motivaram a criação de um programa de previsão de downtime gerado por condições ambientais de dragas de sucção e recalque baseado em modelos matemáticos simplificados. Os movimentos causados por ondas, e as forças e momentos causados na draga por ventos, ondas e correntezas foram analisados de forma a se obter a influência da magnitude e direção de cada um destes parâmetros no comportamento da embarcação. Os principais sistemas da draga influenciados por estas condições foram determinados com base em uma revisão bibliográficas como sendo a potência requerida nos guinchos de varredura, a interação do cortador com o solo e a resistência do sistema de ancoragem, sendo este a tensão de flexão dinâmica na trave do spud ou as tensões de ancoragem pelo sistema de árvore de natal. Três modelos matemáticos foram desenvolvidos para representar estes sistemas. Considerando a não linearidade da interação entre a draga e o solo, este processo foi representado por uma força de reação definida pelo usuário e pela velocidade horizontal do cortador. A eficiência destes modelos foi testada ao aplicá-los em um estudo de caso da dragagem do porto de Açu, na costa brasileira pela draga Taurus II. Valores simultâneos de ondas, ventos e correnteza foram utilizadas como entrada nestes modelos, através da criação de um cenário hipotético de série temporal. Os resultados para ambos os casos demonstraram que a operação seria impossibilitada em função de tensões de flexão dinâmicas no spud maiores que o limite determinado.

As formigas cortadeiras coletam material vegetal para cultivar um fungo simbionte utilizado como fonte de alimento. Colônias de formigas agricultoras podem ser atacadas por micro-organismos invasores e, para proteção do ninho, as formigas se associaram com bactérias produtoras de antibióticos. O objetivo desse trabalho foi estudar os produtos naturais produzidos por micro-organismos associados aos ninhos da formiga cortadeira Atta sexdens rubropilosa. Formigas e amostras dos jardins foram lavadas com solução aquosa estéril e bactérias dos gêneros Serratia, Pseudonocardia e Burkholderia foram isoladas em meio ágar ISP-2 e quitina. A bactéria Serratia marcescens 3B2 produz as substâncias 3-etil-2,5-dimetil-pirazina e 2,5-dimetil-pirazina, que são componentes do feromônio de trilha das formigas Atta sexdens rubropilosa, e ácido indol-3-acético e ácido fenilacético, que são encontrados nas glândulas metapleurais dessas formigas. O genoma dessa bactéria foi sequenciado e os antibióticos andrimide, oocidina e serratamolide foram identificados por genome mining e desreplicação dos extratos. Os estudos biossintéticos da 3-etil-2,5-dimetil-pirazina e 2,5-dimetil-pirazina utilizando precursores isotopicamente marcados revelaram que o aminoácido L-treonina é precursor biossintético dessas substâncias. Bactérias Pseudonocardia spp., isoladas das formigas e jardins do fungo simbionte, inibiram o crescimento do fungo Escovopsis sp., que é parasita dos jardins cultivados pelas formigas. O extrato em acetato de etila da bactéria Pseudonocardia sp. 1B7 foi submetido ao isolamento monitorado pela atividade antifúngica, o que levou a identificação do ácido indol-3-acético como responsável pela inibição observada. O ácido indol-3-acético inibiu seletivamente o crescimento de esporos de cinco linhagens de Escovopsis spp. e não foi ativo contra o fungo cultivado como alimento pelas formigas, Leucoagaricus gongylophorus. O genoma da bactéria Pseudonocardia sp. 1B7 foi sequenciado e a biossíntese do ácido indol-3-acético foi determinada como dependente do aminoácido L-triptofano. A bactéria Burkholderia sp. JB2, isolada do jardim fúngico, produz o antibiótico tropolone, que apresenta elevada atividade inibitória frente ao fungo Escovopsis sp. devido a privação de ferro. Análises de microscopia eletrônica de varredura revelaram que os jardins do fungo simbionte estão encobertos por uma camada resistente a água, que aparenta estar relacionada com a proteção dos jardins. O fungo entomopatogênico Aspergillus nomius ASR3 foi isolado de uma rainha morta de Atta sexdens rubropilosa e as aflatoxinas B1 e G1 foram produzidas por esse fungo em condições laboratoriais e na formiga de onde foi isolado. Os resultados obtidos destacam a importância de metabólitos produzidos pela microbiota bacteriana para a defesa e comunicação das formigas. O conhecimento gerado pode servir de inspiração no desenvolvimento de novas estratégias terapêuticas e formas de controle das formigas cortadeiras que sejam menos prejudiciais ao meio ambiente / Leaf-cutter ants collect plant material to cultivate their food source, a symbiotic fungus. Their colonies can be attacked by invading microorganisms and the ants have associated with protective antibiotic-producing bacteria. This work aimed to study the natural products produced by microorganisms associated with nests of the leaf-cutter ant Atta sexdens rubropilosa. Ants and fungal garden samples were washed with sterile aqueous solution and bacteria of the genera Serratia, Pseudonocardia and Burkholderia were isolated using ISP-2 and chitin agar plates. Serratia marcescens 3B2 produces 3-ethyl-2,5-dimethyl-pyrazine and 2,5-dimethyl-pyrazine, which are components of the ant trail pheromone, and the components of the metapleural glands secretions indole-3-acetic acid and phenylacetic acid were also produced by this strain. Serratia marcescens 3B2 genome was sequenced and the production of the antibiotics andrimid, oocydin A and serratamolide were identified by genome mining and dereplication of the crude extracts. Isotope labeling experiments have revealed that the amino acid L-threonine is the biossyntetic precursor of 2,5-dimethylpyrazine and 3-ethyl-2,5-dimethylpyrazine. Pseudonocardia spp., isolated from the ants and fungal garden, inhibited the growth of the fungus Escovopsis sp., a specialized fungal garden parasite. A bioassay-guided isolation of the Pseudonocardia sp. 1B7 ethyl acetate extract revealed indole-3-acetic acid as the active compound. This natural product selectively inhibited the spores growth of five Escovopsis spp. strains and it was not active against the fungal cultivar Leucoagaricus gongylophorus. Isotope feeding experiments and whole-genome sequencing of Pseudonocardia sp. 1B7 indicated that indole-3-acetic acid is biosynthesized by L-tryptophan dependent pathway. Burkholderia sp. JB2 was isolated from the fungal garden and it produces the antibiotic tropolone, which inhibits the Escovopsis sp. growth by iron privation. The fungal gardens produce a water-resistant layer that seems to be related to the garden protection, as evidenced by scanning electron microscopy analysis. The entomopathogenic fungus Aspergillus nomius ASR3 was isolated from a dead Atta sexdens rubropilosa queen and the aflatoxins B1 and G1 were produced by this fungus in laboratory and natural conditions. The results highlight the importance of bacterial microbiota for the defense and communication of Atta sexdens rubropilosa. These results could contribute for future development of new therapeutic strategies and environmentally friendly techniques to control leaf-cutter ants

Made available in DSpace on 2016-08-10T10:56:11Z (GMT). No. of bitstreams: 1 GUILHERME JOSE DUARTE.pdf: 1565248 bytes, checksum: 899a44dc1093aafd4dc50551520dec77 (MD5) Previous issue date: 2011-11-29 / This study sought to identify the occurrence of Common Mental Disorders (CMD) in workers cutting sugar cane and its relation to the socio-economicenvironmental. To achieve our objective, we established a quantitative field research that investigates the information through data collection using as the Self Report Questionnaire (SRQ 20) in order to identify individuals with suspected cases of CMDs and another instrument to analyze the socio-economic affairs, environment of these workers. Data were analyzed linking to the suspect to TMC with socio-economic-environmental and expressed through assembly of tables. There was a significant number of CMD among workers cutting cane compared with surveys of this kind ever conducted. The vast majority of workers are male, women are outnumbered, although it was found that they have a greater number of suspicion for the TMC. / O presente trabalho buscou identificar a ocorrência de Transtornos Mentais Comuns ( TMC) em trabalhadores do corte de cana e sua relação com os aspectos socioeconômico-ambientais. Para alcançar o objetivo proposto, estabeleceu-se uma pesquisa de campo quantitativa que buscou analisar as informações por meio de coleta de dados utilizando como instrumentos: o Self Report Questionnaire (SRQ 20) a fim de levantar casos de indivíduos com suspeição para TMC, outro instrumento para analisar as condições socioeconomômico- ambientais desses trabalhadores e entrevistas e diário de campo do pesquisador. Os dados foram analisados associando a suspeição para TMC com as condições socioeconômico-ambientais e expressos por meio de montagens de tabelas. Verificou-se um número significativo de TMC entre os trabalhadores do corte de cana se comparados com pesquisas dessa natureza já realizadas. A grande maioria dos Trabalhadores é do sexo masculino, as mulheres são em menor número, apesar disto verificou-se que as mesmas apresentam um número maior de suspeição para o TMC. Conclui-se que os vários fatores socioeconômico-ambientais interferem intensamente no processo de adoecimento mental desses trabalhadores.

A tool path generation method for sculptured surfaces defined by triangular meshes is presented in this thesis along with an algorithm that helps determine the best type of cutter geometry to machine a specific surface. Existing tool path planning methods for sculptured surfaces defined by triangular meshes require extensive computer processing power and result in long processing times mainly since surface topology for triangular meshes is not provided. The method presented in this thesis avoids this problem by offsetting each triangular facet individually. The combination of all the individual offsets make up a cutter location surface. A single triangle offsetting results in many more triangles; many of these are redundant, increasing the time required for data handling in subsequent steps. To avoid the large number of triangles, the proposed method creates a bounding space to which the offset surface is limited. The original surface mesh describes the bounding surface of a solid, thus it is continuous with no gaps. Therefore, the resulting bounding spaces are also continuous and without gaps. Applying the boundary space limits the size of the offset surface resulting in a reduction in the number of triangular surfaces generated. The offset surface generation may result in unwanted intersecting triangles. The tool path planning strategy addresses this issue by applying hidden-surface removal algorithms. The cutter locations from the offset surface are obtained using the depth buffer. The simulation and machining results show that the tool paths generated by this process are correct. Furthermore, the time required to generate tool paths is less than the time required by other methods. The second part of this thesis presents a method for selecting an optimal cutter type. Extensive research has been carried out to determine the best cutter size for a given machining operation. However, cutter type selection has not been studied in-depth. This work presents a method for selecting the best cutter type based on the amount of material removed. By comparing the amount of material removed by two cutters at a given cutter location the best cutter can be selected. The results show that the optimal cutter is highly dependent on the surface geometry. For most complex surfaces it was found that a combination of cutters provides the best results.

The sediment resuspension and turbidity created during dredging operations is both an economical and environmental issue. The movement of sediment plumes created from dredging operations has been predicted with numerical modeling, however, these far-field models need a “source term” or near-field model as input. Although data from field tests have been used to create near-field models that predict the amount of material suspended in the water column, these results are skewed due to limitations such as non-uniform sediment distributions, water currents, and water quality issues. Laboratory investigations have obtained data for turbidity during dredging operations, but these results do not take advantage of the most contemporary testing methods. The purpose of this dissertation is to provide an estimation of turbidity created during a cutter suction dredging operation. This estimation was facilited by the development of resuspension measurement and data acquisition techniques in a laboratory setting. Near-field turbidity measurements around the cutter head were measured in the Haynes Coastal Engineering Laboratory at Texas A&M University. The laboratory contains a dredge/tow tank that is ideal for conducting dredging research. A dredge carriage is located in the dredge/tow tank and is composed of a carriage, cradle, and ladder. Acoustic Doppler Velocimetry (ADV) and Optical Backscatter Sensor (OBS) measurements were taken at specific points around the cutter head. The variables of suction flow rate, cutter speed, and the thickness of cut were investigated to understand their specific effect on turbidity generation and turbulence production around the cutter head. A near-field advection diffusion model was created to predict resuspension of sediment from a cutter suction dredge. The model incorporates the laboratory data to determine the velocity field as well as the turbulent diffusion. The model is validated with laboratory testing as well as field data. Conclusions from this research demonstrate undercutting consistently produced larger point specific turbidity maximum than overcutting in the laboratory testing. An increase in suction flow rate was shown to increase production and decrease turbidity around the cutter head. In general, an increase in cutter speed led to an increase in turbidity. The thickness of cut produced less resuspension for a full cut versus a partial cut. Data for a “shallow cut” also produced less turbidity generation than partial cuts. The numerical model was compared to all laboratory testing cases as well as the Calumet Harbor and New Bedford cutter resuspension data and produced suitable MRA values for all tests. The numerical model produced higher point specific regions of turbidity for undercutting but produced larger mean values of turbidity for overcutting.

Thesis (M.A.)--Florida State University, 2003. / Advisor: Dr. Glen H. Doran, Florida State University, College of Arts and Sciences, Dept. of American and Florida Studies. Title and description from dissertation home page (viewed Mar. 2, 2004). Includes bibliographical references.