Combining human welder (with intelligence and sensing versatility) and automated welding robots (with precision and consistency) can lead to next generation intelligent welding systems. In this dissertation intelligent welding robots are developed by process modeling / control method and learning the human welder behavior. Weld penetration and 3D weld pool surface are first accurately controlled for an automated Gas Tungsten Arc Welding (GTAW) machine. Closed-form model predictive control (MPC) algorithm is derived for real-time welding applications. Skilled welder response to 3D weld pool surface by adjusting the welding current is then modeled using Adaptive Neuro-Fuzzy Inference System (ANFIS), and compared to the novice welder. Automated welding experiments confirm the effectiveness of the proposed human response model. A virtualized welding system is then developed that enables transferring the human knowledge into a welding robot. The learning of human welder movement (i.e., welding speed) is first realized with Virtual Reality (VR) enhancement using iterative K-means based local ANFIS modeling. As a separate effort, the learning is performed without VR enhancement utilizing a fuzzy classifier to rank the data and only preserve the high ranking “correct” response. The trained supervised ANFIS model is transferred to the welding robot and the performance of the controller is examined. A fuzzy weighting based data fusion approach to combine multiple machine and human intelligent models is proposed. The data fusion model can outperform individual machine-based control algorithm and welder intelligence-based models (with and without VR enhancement). Finally a data-driven approach is proposed to model human welder adjustments in 3D (including welding speed, arc length, and torch orientations). Teleoperated training experiments are conducted in which a human welder tries to adjust the torch movements in 3D based on his observation on the real-time weld pool image feedback. The data is off-line rated by the welder and a welder rating system is synthesized. ANFIS model is then proposed to correlate the 3D weld pool characteristic parameters and welder’s torch movements. A foundation is thus established to rapidly extract human intelligence and transfer such intelligence into welding robots.

This Diploma thesis deals with assessment of the influence of two fundamental types of resistance welders operation on chosen power quality parameters at the point of common coupling (PCC) of the power network. The assessed parameters of power quality are the total harmonic distortion of the supply voltage, asymmetry of the supply voltage and the level of short term flicker at the point of common coupling. The assessment is based on the comparison of the results of computer simulations done in PSCad 4.2.0 with the requirements of technical standards. The outcome of this thesis is the determination of allowable limits for physical and operation parameters for the general arrangement of a power distribution network and a resistance welder that should guarantee the power quality compliance.

Made available in DSpace on 2016-03-22T17:27:28Z (GMT). No. of bitstreams: 1 rita nobrega.pdf: 2472570 bytes, checksum: 044be3be25cfb451f3423e176744d9a6 (MD5) Previous issue date: 2014-03-19 / This quantitative research deals with the representation of welder women in Rio Grande city. The corpus consists of the welder women´s interviews, employed in the Ecovix/Engevix Construções Oceânicas, who are nowadays working in the Naval Cluster of the city. This thesis is based on the Critical Discourse Analysis (CDA) according to Norman Fairclough`s research principles and gender studies, and aims at examining these workers profiles, both professional and domestic, throughout the analysis of their discourse, understood as a result of these women`s social practice structured according to their ideologies and social relationship. From such a perspective, the double journey and the enrollment of these women in that profession, up to now a man´s job only, are the issues under discussion in this thesis. It leads us to investigate social-cultural issues that are present in the social imaginary such as the fact of associating the idea that women are subordinated to men, and the intellectual incompetence of production that affects the female figure. Although women have achieved many victories, and shaped a new sexual division of work, these prejudiced and hegemonic discourses are still found in many cultural artefacts and in society. This fact happens because society, still patriarchal, considers gender linked to biological issues and not to the theoretical view that places it within cultural issues. CDA is an interdisciplinary theory that proposes a tridimensional analysis of discourse that comprises text, discourse practice and social practice. Among the several possibilities of choosing among the categories of CDA in order to analyze the corpus, in this thesis, the selected ones are: vocabulary, intertextuality, politeness, and ethos. / Esta pesquisa de cunho qualitativo disserta a respeito da representação das mulheres soldadoras da cidade do Rio Grande. Tem como corpus as respostas das entrevistas realizadas com as soldadoras da empresa Ecovix/Engevix Construções Oceânicas, atuantes no Polo Naval da cidade. À luz da Análise Crítica do Discurso (ACD), segundo Norman Fairclough, e dos estudos de gênero, objetiva verificar o perfil (profissional e doméstico) dessas trabalhadoras por meio do discurso, no entender de que este advém de uma prática social, constituída em meio a ideologias e relações sociais. Nesse viés, a dupla jornada de trabalho e a entrada das mulheres nessa profissão, até então masculina, são os fatos problematizados aqui. A dissertação possibilita refletir acerca de algumas questões socioculturais presentes no imaginário social, como o fato de relacionar as mulheres com a subordinação ao masculino e a incapacidade produtiva e intelectual feminina. Apesar de as mulheres terem conseguido muitas vitórias, configurando uma nova divisão sexual do trabalho, esses discursos preconceituosos e hegemônicos ainda são veiculados nos mais variados artefatos culturais e na sociedade em geral. Isso ocorre porque a sociedade, ainda patriarcal, vê o gênero ligado às questões biológicas e não sob a vertente teórica que o remete às questões culturais. A ACD é uma teoria interdisciplinar que propõe uma análise tridimensional do discurso, a qual engloba o texto, a prática discursiva e a prática social. Dentre as várias possibilidades de categorização do corpus, neste trabalho, são elencadas o vocabulário, a intertextualidade, a polidez e o ethos

Feral pigs, European wild boars and their crosses are ubiquitous and found in all ecological zones from Florida to California. These introduced animals are recorded in 39 US states and four Canadian provinces. Texas currently has an estimated population of 1-4 million pigs with the potential to exceed 4 million based on suitable habitat estimates. Feral pigs can modify local flora and fauna and cause significant physical damage with their rooting activities. They can also reintroduce parasites and pathogens to previously parasite and pathogen free herds of domestic cattle, horses, sheep, and goats. The two overarching objectives of this research were to determine what role feral pigs have in the maintenance and possible distribution of fleas, lice, and ticks common to the three wildlife districts; and if they serve as bridging hosts for the same (or other) arthropods and their natural hosts. The supporting objectives were to establish host records of fleas, lice, and ticks parasitizing feral pigs; determine species assemblies within each of the three wildlife districts; and to compare species assemblies among the wildlife districts. Feral pigs (564) were taken from June 2008 to March 2011 using box, corral, and panel traps in three wildlife districts. Two hundred fifty six fleas, Pulex porcinus (Jordan and Rothschild), were collected from all gender and age classes of feral pigs at the South Texas Plains wildlife district. No fleas were collected at either the Hill Country or Post Oak Savannah wildlife districts. This is the first report of these fleas on feral pigs. Lice and ticks were collected from all gender and age classes of feral pigs from all sample sites. Only hog lice, Haematopinus suis, were collected at all three sample sites. Seven species of ticks were collected from the three sites: Amblyomma americanum, A. cajennense, A. maculatum, Dermacentor albipictus, D. halli, D. variabilis, and Ixodes scapularis. Amblyomma cajennense was collected only at the South Texas Plains sample site; A. americanum and I. scapularis were collected only at the Hill Country and Post Oak sample sites. This study reports that feral pigs are serving as hosts for one species of flea, one species of lice and seven species of ticks common to Texas.

The aim of the thesis is improvement of the recruitment process for the position of welder in a particular company so that the plan to hire 45 new welders would be filled until the end of 2015. As part of the process another opportunity to improve was found and defined. This secondary issue is high fluctuation of welders. Secondary targets of the thesis include mapping, measuring and analysis of the current state of new workers recruitment and also positive motivation of current welders, which create the basis for proposed changes that were later implemented. In the last step the impacts of these changes are controlled and summed up. The whole process follows the DMAIC method steps. During the real project solution tools like Lean management, SIPOC, Flowchart and Ishikawa diagram, first pass yield, A3 report and Benchmarking were used. Above mentioned methodological tools are all described in the practical part of the thesis. In conclusion, it was found out that suggested and implemented amendments improved the recruitment process by 12 percentage points. Fluctuation, the second drawback, is however not possible to measure yet as the impact of the changes will be expected to show within 1 year. Although there was a significant improvement of the whole processes, the plan was not met up to the last day in October 2015. Out of the 45 planned positions, 37 welders in total were casted.

No description available.

An innovative auxiliary control system is developed to cooperate with an unskilled welder in a manual GTAW in order to obtain a consistent welding performance. In the proposed system, a novel mobile sensing system is developed to non-intrusively monitor a manual GTAW by measuring three-dimensional (3D) weld pool surface. Specifically, a miniature structured-light laser amounted on torch projects a dot matrix pattern on weld pool surface during the process; Reflected by the weld pool surface, the laser pattern is intercepted by and imaged on the helmet glass, and recorded by a compact camera on it. Deformed reflection pattern contains the geometry information of weld pool, thus is utilized to reconstruct its $3$D surface. An innovative image processing algorithm and a reconstruction scheme have been developed for (3D) reconstruction. The real-time spatial relations of the torch and the helmet is formulated during welding. Two miniature wireless inertial measurement units (WIMU) are mounted on the torch and the helmet, respectively, to detect their rotation rates and accelerations. A quaternion based unscented Kalman filter (UKF) has been designed to estimate the helmet/torch orientations based on the data from the WIMUs. The distance between the torch and the helmet is measured using an extra structure-light low power laser pattern. Furthermore, human welder's behavior in welding performance has been studied, e.g., a welder`s adjustments on welding current were modeled as response to characteristic parameters of the three-dimensional weld pool surface. This response model as a controller is implemented both automatic and manual gas tungsten arc welding process to maintain a consistent full penetration.

This master’s thesis deals with the design and fabrication of DC arc welder supplied from its own rechargeable battery. Battery cells’ type is LiFePO4 which can provide high currents even at relatively low capacity. The BMS circuits are designed within the battery. Major power part of the welder is a step-down converter with synchronously switching low transistors at the position of free-wheel diode. The converter operates at 100 kHz frequency. The current of the battery welder can be regulated in the range from 0 to 120 A.

The thesis deals with a potential application of welding simulators in basic courses of welding held in welding schools. The first section briefly describes the welding simulators in the global market. There is a detailed description and the control of the welding simulator Virtual Welding, a description of core courses of welding and the necessary welding technology in the following section. Experiments with a welding simulator are carried out in the last section and also their evaluation, comparison and summary of costs.

This master thesis deals with the electron beam welding of the AMS 5659 steel used in industry for special hydraulic cylinders (Fig. 1). A theoretical analysis of electron beam welding and analysis of the influence of selected welding parameters on penetration characteristics are in the first part of the thesis. The second part contains an evaluation of the implemented experimental penetrations on samples of the steel in the hardened condition H1025 and after solution heat. It was also done a properties assessment of the same samples that were been hardened again. The light microscopy (SM), the scanning electron microscopy (SEM) and the measurement method of hardness according to Vickers were used for evaluation and comparison of the steel properties in the region of penetration and the heat affected zones properties.