130 resultados para welded joint


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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Objectives: To investigate the reliability of regional three-dimensional registration and superimposition methods for assessment of temporomandibular joint condylar morphology across subjects and longitudinally.Methods: The sample consisted of cone beam CT scans of 36 patients. The across-subject comparisons included 12 controls, mean age 41.3 +/- 12.0 years, and 12 patients with temporomandibular joint osteoarthritis, mean age 41.3 +/- 14.7 years. The individual longitudinal assessments included 12 patients with temporomandibular joint osteoarthritis, mean age 37.8 +/- 16.7 years, followed up at pre-operative jaw surgery, immediately after and one-year post-operative. Surface models of all condyles were constructed from the cone beam CT scans. Two previously calibrated observers independently performed all registration methods. A landmark-based approach was used for the registration of across-subject condylar models, and temporomandibular joint osteoarthritis vs control group differences were computed with shape analysis. A voxel-based approach was used for registration of longitudinal scans calculated x, y, z degrees of freedom for translation and rotation. Two-way random intraclass correlation coefficients tested the interobserver reliability.Results: Statistically significant differences between the control group and the osteoarthritis group were consistently located on the lateral and medial poles for both observers. The interobserver differences were <= 0.2 mm. For individual longitudinal comparisons, the mean interobserver differences were <= 0.6 mm in translation errors and 1.2 degrees in rotation errors, with excellent reliability (intraclass correlation coefficient >0.75).Conclusions: Condylar registration for across-subjects and longitudinal assessments is reliable and can be used to quantify subtle bony differences in the three-dimensional condylar morphology.

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Experimental investigations were carried out using a Nd:YAG laser operating in pulsed mode for welding a lap joint between thin foil and thick sheet. The pulse energy was varied from 1.5 to 3.0 J at increments of 0.25 J with a 4 ms pulse duration. The base material used for this study was AISI 316L foils with 100 mu m thickness and sheet with 3.0 mm thickness. The welds were analysed by optical and electronic microscopy, tensile shear tests and micro hardness. The results indicate that pulse energy control is of considerable importance to join thin foil and thick sheet with good quality. The ultimate tensile strength of the welded joints increased at first and then decreased as the pulse energy increased. The process appeared to be very sensitive to the gap between couples. Large voids delimited by the molten zone boundary were observed in joints welded with high pulse energy.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The strategic management of information plays a fundamental role in the organizational management process since the decision-making process depend on the need for survival in a highly competitive market. Companies are constantly concerned about information transparency and good practices of corporate governance (CG) which, in turn, directs relations between the controlling power of the company and investors. In this context, this article presents the relationship between the disclosing of information of joint-stock companies by means of using XBRL, the open data model adopted by the Brazilian government, a model that boosted the publication of Information Access Law (Lei de Acesso à Informação), nº 12,527 of 18 November 2011. Information access should be permeated by a mediation policy in order to subsidize the knowledge construction and decision-making of investors. The XBRL is the main model for the publishing of financial information. The use of XBRL by means of new semantic standard created for Linked Data, strengthens the information dissemination, as well as creates analysis mechanisms and cross-referencing of data with different open databases available on the Internet, providing added value to the data/information accessed by civil society.

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This paper reports on an unmodeled, all-sky search for gravitational waves from merging intermediate mass black hole binaries (IMBHB). The search was performed on data from the second joint science run of the LIGO and Virgo detectors (July 2009-October 2010) and was sensitive to IMBHBs with a range up to similar to 200 Mpc, averaged over the possible sky positions and inclinations of the binaries with respect to the line of sight. No significant candidate was found. Upper limits on the coalescence-rate density of nonspinning IMBHBs with total masses between 100 and 450 M-circle dot and mass ratios between 0.25 and 1 were placed by combining this analysis with an analogous search performed on data from the first LIGO-Virgo joint science run (November 2005-October 2007). The most stringent limit was set for systems consisting of two 88 M-circle dot black holes and is equal to 0.12 Mpc(-3) Myr(-1) at the 90% confidence level. This paper also presents the first estimate, for the case of an unmodeled analysis, of the impact on the search range of IMBHB spin configurations: the visible volume for IMBHBs with nonspinning components is roughly doubled for a population of IMBHBs with spins aligned with the binary's orbital angular momentum and uniformly distributed in the dimensionless spin parameter up to 0.8, whereas an analogous population with antialigned spins decreases the visible volume by similar to 20%.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The process of electric arc welding with shielding gas (GMAW) is being increasingly used in various industrial applications. This process occurs by which an electric arc is established between the work piece and a consumable in the form of wire, the arc melts the wire continuously as it is fed to the weld pool. The weld metal is protected from the atmosphere by flowing a gas (or gas mixture) inert or active. This paper presents a study of the welding process GMAW - MIG on aluminum tubes, alloy 6101 - T6, used in the manufacture of armored busbar, intended for driving electric power plants. 5(five) were welded specimens, changing certain welding parameters at each time was monitored welding joint as well as the interpass temperature. Tests were performed bending, tensile and macrographical analysis of body-of-evidence and through its results was possible to reach a better welding condition, which minimizes the appearance of pores, since the porosity has great influence on the mechanical strength and electrical conductivity of welded pipes

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When a bolted joint is loaded in tension with dynamically, part of this load is absorbed by the bolt and rest is absorbed by the joint material. What determines the portion that is to absorbed by the bolt is the joint stiffness factor. This factor influences the tension which corresponds to pre-load and the safety factor for fatigue failure, thus being an important factor in the design of bolted joints. In this work, three methods of calculating the stiffness factor are compared through a spreadsheet in Excel software. The ratio of initial pre-load and the safety factor for fatigue failure depending on the stiffness factor graph is generated. The calculations for each method show results with a small difference. It is therefore recommended that each project case is analyzed, and depending on its conditions and the range of stiffness values, the more or less rigid method about the safety factor for fatigue failure is chosen. In general, the approximation method provides consistent results and can be easily calculated

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Pós-graduação em Engenharia Mecânica - FEG

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The aim of this work was to evaluate the corrosion resistance of AuPdAgIn alloy, submitted to laser beam welding, in 0.9% NaCl solution, using electrochemical techniques. Measures of the open circuit potential (OCP) versus time were applied to electrochemical experiments, as well as potentiodynamic direct scanning (PDS) and electrochemical impedance spectroscopy (EIS) on AuPdAgIn alloy, submitted to laser beam welding in 0.9% NaCl solution. Some differences observed in the microstructure can explain the results obtained for corrosion potential, Ecorr, and corrosion resistance, Rp. EIS spectra have been characterized by distorted capacitive components, presenting linear impedance at low frequencies, including a non-uniform diffusion. The area of the laser weld presented corrosion potential slightly superior when compared to the one of the base metal. The impedance results suggest the best resistant corrosion behavior for laser weld than base metal region. This welding process is a promising alternative to dental prostheses casting.

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Sacroiliac joint (SIJ) pain is responsible for up to 40% of all cases of lumbar back pain. Objective Report the long-term efficacy of radiofrequency denervation for sacroiliac joint pain at six, twelve and eighteen months. Method Third-two adults’ patients with sacroiliac join pain diagnosis were included for a prospective study. Primary outcome measure was pain intensity on the Numeric Rating Scale (NRS). Secondary outcome measure was Patient Global Impression of Change Scale (PGIC). Results Short-term pain relief was observed, with the mean NRS pain score decreasing from 7.7 ± 1.8 at baseline to 2.8 ± 1.2 at one month and to 3.1 ± 1.9 at six months post-procedure (p < 0.001). Long-term pain relief was sustained at twelve and eighteen months post-procedure, with NRS pain remaining at 3.4 ± 2.1 and 4.0 ± 2.7, respectively. Conclusion Radiofrequency denervation of the SIJ can significantly reduce pain in selected patients with sacroiliac syndrome.

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Structured AbstractObjectivesTo investigate the 3D morphological variations in 169 temporomandibular ioint (TMJ) condyles, using novel imaging statistical modeling approaches.Setting and sample populationThe Department of Orthodontics and Pediatric Dentistry at the University of Michigan. Cone beam CT scans were acquired from 69 subjects with long-term TMJ osteoarthritis (OA, mean age 39.115.7years), 15 subjects at initial consult diagnosis of OA (mean age 44.914.8years), and seven healthy controls (mean age 4312.4years).Materials and methods3D surface models of the condyles were constructed, and homologous correspondent points on each model were established. The statistical framework included Direction-Projection-Permutation (DiProPerm) for testing statistical significance of the differences between healthy controls and the OA groups determined by clinical and radiographic diagnoses.ResultsCondylar morphology in OA and healthy subjects varied widely with categorization from mild to severe bone degeneration or overgrowth. DiProPerm statistics supported a significant difference between the healthy control group and the initial diagnosis of OA group (t=6.6, empirical p-value=0.006) and between healthy and long-term diagnosis of OA group (t=7.2, empirical p-value=0). Compared with healthy controls, the average condyle in OA subjects was significantly smaller in all dimensions, except its anterior surface, even in subjects with initial diagnosis of OA.ConclusionThis new statistical modeling of condylar morphology allows the development of more targeted classifications of this condition than previously possible.