The Experts below are selected from a list of 222423 Experts worldwide ranked by ideXlab platform
D C Watts - One of the best experts on this subject based on the ideXlab platform.
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exotherm behavior of the polymer based provisional crown and fixed partial denture materials
Journal of Prosthetic Dentistry, 2004Co-Authors: D C WattsAbstract:Abstract Objectives The objective of this in vitro study was to evaluate the exothermic reaction during polymerization of the polymer-based provisional crown and fixed partial denture materials. Methods Three dimethacrylate-based materials and one monomethacrylate-based material were selected. The specimens were pre-conditioned to 23°C. Temperature changes of the materials during polymerization were recorded in a model test-cavity overlying a type K thermocouple. Peak Temperature, time to reach Peak Temperature and total Peak area were determined. The data were statistically analyzed using one-way ANOVA at a significance level of 0.05. Results All materials exhibited exotherm release ranging from 5.1 to 12.7°C. Trim gave a Peak Temperature that was not significantly lower than those of Protemp 3 Garant and Luxatemp, but fast set Temphase showed a significantly higher Peak Temperature than the other materials. All materials showed no significant differences in the total Peak area. Trim showed the slowest exotherm reaction; its time to reach the Peak Temperature was ca. 10 min after mixing, while ca. 2 min for the other materials. Significance The dimethacrylate-based materials (except for fast set Temphase) exhibited no significant differences in Peak Temperature and total Peak area from the monomethacrylate-based material with slower exotherm reaction. A reformulation of the dimethacrylate-based materials could be envisaged to generate a material with a slightly slower setting and a reduced Peak Temperature.— Reprinted with permission from The Academy of Dental Materials .
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exotherm behavior of the polymer based provisional crown and fixed partial denture materials
Dental Materials, 2004Co-Authors: D C WattsAbstract:Abstract Objectives: The objective of this in vitro study was to evaluate the exothermic reaction during polymerization of the polymer-based provisional crown and fixed partial denture materials. Methods: Three dimethacrylate-based materials and one monomethacrylate-based material were selected. The specimens were pre-conditioned to 23 °C. Temperature changes of the materials during polymerization were recorded in a model test-cavity overlying a type K thermocouple. Peak Temperature, time to reach Peak Temperature and total Peak area were determined. The data were statistically analyzed using one-way ANOVA at a significance level of 0.05. Results: All materials exhibited exotherm release ranging from 5.1 to 12.7 °C. Trim gave a Peak Temperature that was not significantly lower (p>0.05) than those of Protemp 3 Garant and Luxatemp, but fast set Temphase showed a significantly higher (p 0.05) in the total Peak area. Trim showed the slowest exotherm reaction; its time to reach the Peak Temperature was ca. 10 min after mixing, while ca. 2 min for the other materials. Significance: The dimethacrylate-based materials (except for fast set Temphase) exhibited no significant differences in Peak Temperature and total Peak area from the monomethacrylate-based material with slower exotherm reaction. A reformulation of the dimethacrylate-based materials could be envisaged to generate a material with a slightly slower setting and a reduced Peak Temperature.
T Debroy - One of the best experts on this subject based on the ideXlab platform.
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neural network models of Peak Temperature torque traverse force bending stress and maximum shear stress during friction stir welding
Science and Technology of Welding and Joining, 2012Co-Authors: V Manvatkar, Amit Arora, A De, T DebroyAbstract:AbstractTool and workpiece Temperatures, torque, traverse force and stresses on the tools are affected by friction stir welding (FSW) variables such as plate thickness, welding speed, tool rotational speed, shoulder and pin diameters, pin length and tool material. Because of the large number of these welding variables, their effects cannot be realistically mapped by experiments. Here, we develop, test and make available a set of five neural networks to calculate the Peak Temperature, torque, traverse force and bending and equivalent stresses on the tool pin for the FSW of an aluminium alloy. The neural networks are trained and tested with the results from a well tested, comprehensive, three-dimensional heat and material flow model. The predictions of Peak Temperature and torque are also compared with appropriate experimental data for various values of shoulder radius and tool revolutions per minute. The models can be used even beyond the range of training with predictable levels of uncertainty.
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back of the envelope calculations in friction stir welding velocities Peak Temperature torque and hardness
Acta Materialia, 2011Co-Authors: Amit Arora, T Debroy, H K D H BhadeshiaAbstract:Given the complexity and resource requirements of numerical models of friction stir welding (FSW), well-tested analytical models of materials flow, Peak Temperatures, torque, and weld properties are needed. Here an approximate analytical technique for the calculation of three-dimensional material flow during FSW is proposed considering the motion of an incompressible fluid induced by a solid rotating disk. The accuracy of the calculations is examined for the welding of three alloys. For the estimation of Peak Temperatures, the accuracy of an existing dimensionless correlation is improved using a large volume of recently published data. The improved correlation is tested against experimental data for three aluminum alloys. It is shown that the torque can be calculated analytically from the yield stress using estimated Peak Temperatures. An approximate relation between the hardness of the thermomechanically affected zone and the chemical composition of the aluminum alloys is proposed.
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dimensionless correlation to estimate Peak Temperature during friction stir welding
Science and Technology of Welding and Joining, 2006Co-Authors: R Nandan, T DebroyAbstract:AbstractA dimensionless correlation has been developed based on Buckingham's π-theorem to estimate the Peak Temperature during friction stir welding (FSW). A relationship is proposed between dimensionless Peak Temperature and dimensionless heat input. Apart from the estimation of Peak Temperature, it can also be used for the selection of welding conditions to prevent melting of the workpiece during FSW. The correlation includes thermal properties of the material and the tool, the area of the tool shoulder and the rotational and translation speeds of the tool. The Peak Temperatures reported in the literature during FSW of various materials and welding conditions were found to be in fair agreement with the proposed correlation.
Zhinong Ying - One of the best experts on this subject based on the ideXlab platform.
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RF Compliance Study of Temperature Elevation in Human Head Model Around 28 GHz for 5G User Equipment Application: Simulation Analysis
IEEE Access, 2018Co-Authors: Mats Gustafsson, Zhinong YingAbstract:The crowdedness of current cellular bands and the demand for higher transmission speed prompt the use of the millimeter-wave spectrum for the next-generation mobile communication. In the millimeter-wave frequencies, the dosimetric quantity for human exposure to electromagnetic fields changes from the specific absorption rate to incident power density. In this paper, we used 28-GHz beam-steering patch arrays, a dipole antenna, and plane waves to investigate the Temperature elevation in a multi-layer model of human head and its correlation with power density metrics. The power density averaged over one square-centimeter in free space and the Peak Temperature elevation in tissue at 28 GHz have good correlation. The Peak Temperature elevation indicated by the power density averaged one square-centimeter also agrees well with the Peak Temperature elevation induced by the plane waves. The results show that the averaging area of a few square-centimeters may be a good candidate for the spatial-average power density. The findings provide valuable input to the ongoing revision and updating of relevant safety standards and guidelines.
H K D H Bhadeshia - One of the best experts on this subject based on the ideXlab platform.
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back of the envelope calculations in friction stir welding velocities Peak Temperature torque and hardness
Acta Materialia, 2011Co-Authors: Amit Arora, T Debroy, H K D H BhadeshiaAbstract:Given the complexity and resource requirements of numerical models of friction stir welding (FSW), well-tested analytical models of materials flow, Peak Temperatures, torque, and weld properties are needed. Here an approximate analytical technique for the calculation of three-dimensional material flow during FSW is proposed considering the motion of an incompressible fluid induced by a solid rotating disk. The accuracy of the calculations is examined for the welding of three alloys. For the estimation of Peak Temperatures, the accuracy of an existing dimensionless correlation is improved using a large volume of recently published data. The improved correlation is tested against experimental data for three aluminum alloys. It is shown that the torque can be calculated analytically from the yield stress using estimated Peak Temperatures. An approximate relation between the hardness of the thermomechanically affected zone and the chemical composition of the aluminum alloys is proposed.
Amit Arora - One of the best experts on this subject based on the ideXlab platform.
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neural network models of Peak Temperature torque traverse force bending stress and maximum shear stress during friction stir welding
Science and Technology of Welding and Joining, 2012Co-Authors: V Manvatkar, Amit Arora, A De, T DebroyAbstract:AbstractTool and workpiece Temperatures, torque, traverse force and stresses on the tools are affected by friction stir welding (FSW) variables such as plate thickness, welding speed, tool rotational speed, shoulder and pin diameters, pin length and tool material. Because of the large number of these welding variables, their effects cannot be realistically mapped by experiments. Here, we develop, test and make available a set of five neural networks to calculate the Peak Temperature, torque, traverse force and bending and equivalent stresses on the tool pin for the FSW of an aluminium alloy. The neural networks are trained and tested with the results from a well tested, comprehensive, three-dimensional heat and material flow model. The predictions of Peak Temperature and torque are also compared with appropriate experimental data for various values of shoulder radius and tool revolutions per minute. The models can be used even beyond the range of training with predictable levels of uncertainty.
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back of the envelope calculations in friction stir welding velocities Peak Temperature torque and hardness
Acta Materialia, 2011Co-Authors: Amit Arora, T Debroy, H K D H BhadeshiaAbstract:Given the complexity and resource requirements of numerical models of friction stir welding (FSW), well-tested analytical models of materials flow, Peak Temperatures, torque, and weld properties are needed. Here an approximate analytical technique for the calculation of three-dimensional material flow during FSW is proposed considering the motion of an incompressible fluid induced by a solid rotating disk. The accuracy of the calculations is examined for the welding of three alloys. For the estimation of Peak Temperatures, the accuracy of an existing dimensionless correlation is improved using a large volume of recently published data. The improved correlation is tested against experimental data for three aluminum alloys. It is shown that the torque can be calculated analytically from the yield stress using estimated Peak Temperatures. An approximate relation between the hardness of the thermomechanically affected zone and the chemical composition of the aluminum alloys is proposed.
