1,721,081 research outputs found
CAD-based design for welding (DFW) method
No full textThe paper provides a method to integrate Design for Welding (DFW) method with CAD systems. The method is based on three main phases: (i) definition of DFW rules for the development of mechanical products, (ii) link of DFW rules with product geometrical features that are available by the investigation of the 3D model, and (iii) integration with CAD systems to support product design review. A method and a software tool are described including their features to help designers in the product development process. Case study aims to validate the proposed method in the identification of assembly issues early in the product development process. The CAD-based DFW tool is a useful assistant to avoid design problems related to the welding technology
Tears of the rotator cuff associated with neurologic disorders: a description of two cases
No full textBased on their clinical experience with the two cases described, the authors analyze the association between surgically treatable tear of the rotator cuff and neurologic pathology. A semeiologic sign is emphasized, which may be of help in differential diagnosis involving isolated lesion of the rotator cuff. Furthermore, after a review of the literature, the authors express doubts as to the type of surgical treatment to be carried out
Comparative life cycle assessment of metal arc welding technologies by using engineering design documentation
No full textPurpose: The paper aims to analyze and compare the environmental performances of metal arc welding technologies: gas metal arc welding (GMAW), shielded metal arc welding (SMAW), gas tungsten arc welding (GTAW), submerged arc welding (SAW), and flux-cored arc welding (FCAW). Welding is considered one of the most energy-intensive processes in manufacturing. This study was performed in accordance with the international standard ISO 14040/14044 by using attributional life cycle assessment (aLCA). Methods: The functional unit is defined as the “the development of 1 metre of welding seam (qualified by ASME section IX requirements) to join 25 millimetres thick of metal plates made in carbon steel material and considering a V-bevel configuration.” Different configurations of base/filler materials and standardized bevel geometries have been analyzed as welding scenarios. The inventory considers all inputs (e.g., electric energy and filler material) and outputs (e.g., fume emissions and slags) involved in each welding process. A framework for data collection starting from available project documentation is presented as an innovative solution for the inventory phase. The impact assessment includes the human health, resources (midpoints/endpoint), and ecosystems (endpoint) categories from the ReCiPe (H) and cumulative energy demand (CED) methods. Results and discussion: This study reveals a notable dominance in terms of the environmental burdens of GTAW and SMAW processes, as they present higher impacts in most of the impact categories. SMAW is the most energy-consuming process, and this aspect is reflected in the environmental performance. Conversely, GMAW presents the least environmental load, accounting for less than one third compared with GTAW in terms of the CED indicator and performing very well in terms of the ReCiPe endpoint indicator. Via analysis of different scenarios, the main outcomes are the following: (i) the use of V bevels significantly increases the environmental load when the metal plate thickness increases and (ii) the use of specific materials such as Inconel alloy exacerbates the environmental concerns associated with welding processes. Conclusions: The use of project documentation allows robust analysis of welding activity. Sensitivity analysis shows how the range of values for specific parameters (e.g., volts and amps) affects each technology in a different manner. Indeed, those ranges have a limited impact on the result accuracy (up to 20%) for more automatized welding processes (e.g., GMAW, SAW, and FCAW), in which only a small number of parameters are set by the operator, and the operator skills are less influential on the quality of the weld
Calcific tendinitis of the rotator cuff with trochiteal osteolysis. A rare clinical radiologic complication
No full textAmong cases of calcific tendinitis that are unresponsive to any type of non-surgical treatment, the authors report 3 cases, out of a total of 32 submitted to surgery, that presented with an osteolytic cavity filled with calcium salts in the insertional region of the supraspinous tendon. These patients presented with pain that they had been experiencing for an average of 4 years, with acute recurrent episodes. When this pathology can be determined radiographically, early surgery is recommended, considering that any type of non-surgical treatment is destined to fail
Can a short-term hiking training change cardiovascular autonomic control in healthy sedentary women?
No full textWe tested the hypothesis that two weeks of training performed at moderate intensity can induce cardiovascular autonomic control changes in adult sedentary women. To this aim, we continuously recorded finger arterial pressure in 8 women (25 yy ± 7; 68 kg ± 11, 165 cm ± 8) before and immediately after a training program of daily trekking (3-6 hours d-1) performed at near sea level and on irregular and undulating terrain. 8 min records were taken in 3 steady state conditions: 1) supine, 2) 70° passive head up tilting, 3) back to supine. Pressure waveforms were transformed into time series of systolic and diastolic pressure, heart rate, stroke volume, cardiac output and total peripheral resistance. Pressure and heart rate time series underwent auto and cross correlation spectral analysis to detect spontaneous oscillations in the low (0.05-0.15 Hz) and high (0.20-0.30 Hz) frequency range. All variables (measured and calculated) were compared in the three conditions before and after training; also transients (tilt-up/tilt-down) were recorded and visually compared.
Overall, we did not find pre/post training significant differences in any of the variables, both in the time and in the frequency domain. Also the time course of changes during tilt-up and down was quite similar for individual subjects.
We concluded that two weeks of training performed at moderate intensity were not able to induce significant changes in the cardiovascular autonomic control
An analytical assessment of the influence of skin imperfections on the indentation collapse mechanism in composite sandwich beams
No full textThe influence of skin imperfections, in the form of delamination damage or thickness variations, on the indentation collapse mechanism in composite sandwich beams with compressive yielding cores is studied using the models of non-prismatic beam and beam-column resting on a nonlinear Winkler foundation. Upper and lower threshold solutions are derived for the indentation response and collapse load and the transition between the two limits is defined as a function of size, magnitude and position of the imperfections. In beams where global bending effects are not negligible, the collapse load is limited from above by the indentation collapse load of beams with rigid-plastic cores and the face wrinkling collapse load of beams with elastic cores; the transition between the two limits is controlled by material/structure properties and the magnitude of the imperfections. Characteristic lengths, which depend on material and geometrical properties, define the minimum size of the imperfections with the strongest effect on the solution and the minimum distance between load and imperfections with no effect on the solution
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