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Estudo do processo de soldagem a ponto por fricção de juntas dissimilares entre ligas de alumínio e titânio
(Universidade Federal de São Carlos, 2016-12-09) Plaine, Athos Henrique; Alcântara, Nelson Guedes de; https://lattes.cnpq.br/3123107570992184; https://lattes.cnpq.br/8992899102845408
Multimaterial structures between aluminum and titanium alloys are a technologically attractive field of research and their increasing use in the transportation sector for weight and emission reduction is part of the motivation of this study. The currently used techniques are either too expensive or limited in performance, especially by excessive formation of undesirable intermetallic compounds, opening opportunities for innovation in this area. Friction spot welding (FSpW), a solid state joining process recently developed by Helmholtz Zentrum Geesthacht, has proven to be one of the promising technologies for joining dissimilar materials as it involves short steps and low thermal cycles, also with the advantages of adding no weight to the structure and having geometrical compatibility to replace rivets. The present work studies the feasibility in welding AA5754-H22/Ti6Al4V and AA6181-T4/Ti6Al4V joints through FSpW. In addition, it is intended to establish the microstructure/ properties / process relationships of the resultant joints, in order to understand the formation and growth of the joining interface and its consequences on the mechanical performance. The proposed joints are produced in overlap configuration through different combinations of parameters, which were established by statistical methods involving design of experiments, and later submitted to mechanical and metallurgical characterization. The results reveal that Al/Ti dissimilar joints with high strength and reproducibility can be produced by using FSpW. The mechanical behavior of the joints presents a strong dependence on the intermetallic thickness formed at the bounding interface, identified as TiAl3. Tool rotational speed and dwell time are key process parameters in controlling the resistance of welded joints. Moreover, the bending load associated to differences in stiffness and/or thickness of the welded specimen appears as an important variable influencing the crack propagation path during shear and fatigue tests.
Identificação dos principais atributos para o projeto de uma rede cicloviária
(Universidade Federal de São Carlos, 2016-12-09) Pitilin, Taiany Richard; Sanches, Suely da Penha; https://lattes.cnpq.br/3857424839674606; https://lattes.cnpq.br/2653656667798172
The aim of this research project was to identify what the key attributes that should be considered in the design of a cycling network from the point of view of cyclists and transport planning experts. The methodology for development of research consisted of: (1) application of questionnaires to cyclists on the factors that influence the choice of your routes, (2) application of questionnaires to experts about what attributes should be considered in planning a cycling route urban area and (3) Analysis of the results using statistical methods. The survey results were analyzed using the method of successive intervals, also applying t test and ANOVA for comparison of results. From the results of these two studies was possible to identify the aspects considered important for cyclists and experts, analyzing their divergences and proposing guidelines for project cycling networks that meet the needs of cyclists and attract new users.
Diagnóstico de influência local no modelo de calibração ultraestrutural com réplicas
(Universidade Federal de São Carlos, 2016-12-09) Andrade, Bruno Pinheiro de; Aoki, Reiko; https://lattes.cnpq.br/0621850261580868; https://lattes.cnpq.br/8657847482314007
This paper aims to present the local influence diagnostic methodology of Cook (1986) along with the selection of the appropriate perturbation schemes proposed by Zhu et al. (2007) in ultrastructural calibration model with replicas. The methodology of Cook (1986) will be used to investigate the robustness and sensitivity of model, where the adopted perturbation schemes were weighting cases and response variables. Perturbing the model and/or data in an arbitrary way can lead to miss interpretations of diagnostic analysis and wrong conclusions. Therefore, this study will evaluate the induced perturbations according to the methodology of Zhu et al. (2007) and if the perturbations are not suitable, we will propose a new way of perturbing the model or the data. As an application it was considered a data set with balanced repeated replication to evaluate which levels and laboratories exercise a disproportional effect on inferences made in the model.
Conservação de bio-recursos algais no Brasil: estabelecimento de um banco criopreservado
(Universidade Federal de São Carlos, 2016-12-09) Tessarolli, Letícia Piton; Day, John Godfrey; Vieira, Armando Augusto Henriques; https://lattes.cnpq.br/4428377384377272; https://lattes.cnpq.br/4024406734152899
The establishment of culture collections is a vital aspect for the conservation freshwater microalgae, which are a very diverse group of organisms with important ecological functions on the ecosystems maintenance and an immense although still sparsely explored biotechnological potential, particularly for the use of metabolites and biodiesel production. The traditional protocol for culture maintenance is the serial subculturing of metabollicaly active cultures. Although strains have been maintained in metabolically active cultures for decades, there are several reports of loss of characteristics for the organisms thus maintained, and an increase in the number of strains could be the cause for logistical challenges on the maintenance regimes and elevated costs with material and functionalism. Cryopreservation, which is the maintenance of organisms at ultra-low temperatures to the point that all cellular metabolic functions are paused, appears as a recommended alternative for the maintenance of long-term culture collections. The use of this technique allows the maintenance of samples for long periods of time with minimal handling, severely reducing the maintenance costs, while maintaining the stability of cultures, which should be stored at ultra-low temperatures to eliminate the occurrence of intracellular chemical processes. The Freshwater Microalgae Culture Collection (CCMA-UFSCar) currently maintains approximately 700 microalgae strains in metabolically active cultures, which is reaching maximum support capacity for routine maintenance practices. The requirements with cultures maintenance will also, consequently, affect the provision services of the collection, which are the basis of research of a large number of projects throughout Brazil. Thus, the main objective of this project was to test the feasibility of the use of cryopreservation as a technique to maintain algal cultures in this culture collection. For this, initially positive results were obtained for the application of a standard freezing protocol, particularly for green coccoid algae. However, larger and more complex organisms are still recalcitrant to freezing, with low rates of recovery, which will require further research and adaptation of the protocols to meet the particularities of each strain. In parallel to the establishment of the cryopreserved biobank for CCMA-UFSCar, projects were developed in order to further clarify details and consequences of the process of freezing and storing organisms at low temperatures, seeking to improve the success rates for the implementation of this technique. The effects of the presence of contaminating organisms on the microalgae cultures on the response of strains to freezing, and consequently on the formation of viable and robust post-thaw cultures, were verified a few selected non-axenic strains. It was noticed that the choice of cryoprotectant solution (CPA), used to protect cells during freezing, may be crucial for post-thaw recovery, and it is necessary to search for balance between obtaining the highest possible viability levels and avoiding the extreme proliferation of contaminating organisms, which could lead to inhibition in the recovery and quality of the desired algal cultures after the process. In addition to direct survival to the freezing process, which is a potentially damaging for cells, the longevity of samples maintained at different temperatures was also tested, aiming to establish the simplest and most cost-effective procedure to ensure the long term survival of frozen samples. It was observed that the storage temperatures, as well as the CPA used during freezing, were significant aspects to guarantee the continued viability of the frozen cultures, and only samples maintained immersed in liquid nitrogen were sufficiently protected against temperature fluctuations, ensuring the survival of all the samples for longer periods. Furthermore, the continuity of the viability for samples maintained immersed in liquid nitrogen was also observed in a study with samples maintained on these conditions for up to 40 years at Culture Collection of Algae and Protozoa (CCAP, UK). The freezing process per se is potentially damaging to the cultures during the process, which might be the cause for functional and genetic differences in cells that have undergone this process. Thus, biochemical and genetic analysis were used to verify the stability of the cultures submitted to the freezing protocol. To ensure the successful implementation of a cryopreserved microalgae bank for CCMA-UFSCar, in addition to viability and stability measures, it is necessary to establish protocols for sample management and routine maintenance. Thus, a case study was carried out with the experiences acquired in CCAP during the 40 years of the history of a cryopreserved bank, and how the application of these techniques can benefit the quality control and management of CCMA-UFSCar, facilitating the implementation of the cryopreserved biobank for this culture collection.
Restauração de imagens com precisão subpixel utilizando restrições convexas
(Universidade Federal de São Carlos, 2016-12-09) Antunes Filho, Amauri; Homem, Murillo Rodrigo Petrucelli; https://lattes.cnpq.br/4099700446922080; https://lattes.cnpq.br/1275519242542531
The super-resolution aims to obtain a higher resolution image, using information from one or more low resolution images. There are different applications where super-resolution may be used, such as medical and forensic images. This work proposes a study and development of algorithms, based on Tekalp and Sezan’s algorithm, using the projection onto convex sets theory, in order to obtain super-resolution, therefore obtaining a higher resolution image, from a low resolution images set, with subpixel informations. We proposed the adition of a convex restriction based on Richardon-Lucy’s algorithm, modified to be weighted by Canny’s filter, along with total variation regularization, aiming to restore frequencies lost during high resolution images decimation and degradation processes . Therefore, we have a hybrid approach, that implements spatial and spectral super-resolution simultaneously, based on projection onto convex sets. The obtained results by the proposed algorithms were compared to Tekalp and Sezan’s base algorithm. The visual analysis of the images, along with the mean square error were taken in consideration for comparisons. In development, grayscale images were used, but the methods are extensible for color images. Results showed improvement in the obtained images, with less noise, blurring and more edge definition than the low resolution images. We conclude that the approach has potential for medical applications and forensic computation.
Efeitos do treinamento resistido na morfologia, propriedades e marcadores de remodelamento de matriz extracelular óssea em modelo de ratas ovariectomizadas
(Universidade Federal de São Carlos, 2016-12-09) Pisani, Graziéle Fernanda Deriggi; Araújo, Heloísa Sobreiro Selistre de; https://lattes.cnpq.br/4065824911933203; https://lattes.cnpq.br/4835384433555310
Absence of estrogen on menopause leads to detrimental consequences, including osteoporosis, which is characterized by unbalanced bone extracellular matrix (ECM) remodeling. Bone resistance to fracture is related to bone mass, structure and architecture including bone ECM changes. Resistance training (RT) has shown beneficial effects on prevention and treatment of osteoporosis, however, there are few studies regarding RT role in bone remodeling in different scales, such as bone composition and structure until matrix metalloproteinases (MMPs) in ovariectomy (OVX) model. Aims: To evaluate RT effects on bone properties, morphology and bone ECM remodeling markers in an OVX rat model. Methods: Thirty six female Sprague Dawley rats were divided into four groups: sham sedentary, OVX sedentary, sham RT and OVX RT. Rats performed RT for 10 weeks in which they climbed a ladder with progressive loads attached to the tails. Tibias were stored for biometrical, biomechanical, biophysical and biochemical analysis. Femurs were stored to morphological, gene expression and gelatin zymography analysis. Results: OVX decreased bone mineral density, bone mineral content, stiffness, maximal load, calcium content, trabecular number and connectivity and MMP-13 gene expression. Furthermore, OVX increased RUNX-2 and OPG gene expression and MMP-2 activity. RT was efficient in prevent or reverse almost all of alterations. Conclusion: Estrogen absence osteoporosis affects bone mass and other factors involved in bone ECM remodeling and RT showed be efficient in prevent or reverse these harmful effects.