The Experts below are selected from a list of 59178 Experts worldwide ranked by ideXlab platform
Zhen Bing Hou - One of the best experts on this subject based on the ideXlab platform.
-
thermal analysis of laser surface transformation hardening optimization of process parameters
International Journal of Machine Tools & Manufacture, 2004Co-Authors: R Komanduri, Zhen Bing HouAbstract:Abstract This paper deals with the optimization of process parameters for maximum productivity (given by the product of scanning velocity and cross feed) in laser transformation hardening. The process parameters considered are laser beam power, P ; laser beam diameter, D b ; and the Heat Intensity distribution, namely, normal, bimodal, or uniform. A thermal analysis of the laser surface transformation hardening of gears was conducted (based on Jaeger’s classical moving Heat source method) by considering the laser beam as a moving plane (disc) Heat source to establish the temperature rise distribution in the workpiece (gear) of finite width. In a recent investigation [Int. J. Heat Mass Transfer 44 (2001) 2845], the authors considered the case of a Heat source with a pseudo-Gaussian (or normal) distribution of Heat Intensity. The analytical results were compared with the experimental results published in the literature. In laser Heat treatment of steel, it is generally considered preferable to use a wider Heat Intensity distribution, such as uniform or bimodal, for it enables more uniform case hardening depth. In this paper, this model is extended to cover bimodal and uniform distributions and compared with the normal distribution. Scanning velocities for no surface melting and for a case hardening depth of 0.1 mm were determined for surface transformation hardening of AISI 1036 (EN 8) steel for a range of laser beam powers, P , laser beam diameters, D b , and various Heat Intensity distributions. Since diffusion during the Heat treatment (surface transformation hardening) process is a time dependent phenomenon, based on the literature review, an interaction time of 15 ms was taken as a basis. It is hoped that laser industry with adequate facilities available can validate the thermal analysis and subsequent optimization presented in this paper.
-
Thermal analysis of laser surface transformation hardening—optimization of process parameters
International Journal of Machine Tools and Manufacture, 2004Co-Authors: R Komanduri, Zhen Bing HouAbstract:Abstract This paper deals with the optimization of process parameters for maximum productivity (given by the product of scanning velocity and cross feed) in laser transformation hardening. The process parameters considered are laser beam power, P ; laser beam diameter, D b ; and the Heat Intensity distribution, namely, normal, bimodal, or uniform. A thermal analysis of the laser surface transformation hardening of gears was conducted (based on Jaeger’s classical moving Heat source method) by considering the laser beam as a moving plane (disc) Heat source to establish the temperature rise distribution in the workpiece (gear) of finite width. In a recent investigation [Int. J. Heat Mass Transfer 44 (2001) 2845], the authors considered the case of a Heat source with a pseudo-Gaussian (or normal) distribution of Heat Intensity. The analytical results were compared with the experimental results published in the literature. In laser Heat treatment of steel, it is generally considered preferable to use a wider Heat Intensity distribution, such as uniform or bimodal, for it enables more uniform case hardening depth. In this paper, this model is extended to cover bimodal and uniform distributions and compared with the normal distribution. Scanning velocities for no surface melting and for a case hardening depth of 0.1 mm were determined for surface transformation hardening of AISI 1036 (EN 8) steel for a range of laser beam powers, P , laser beam diameters, D b , and various Heat Intensity distributions. Since diffusion during the Heat treatment (surface transformation hardening) process is a time dependent phenomenon, based on the literature review, an interaction time of 15 ms was taken as a basis. It is hoped that laser industry with adequate facilities available can validate the thermal analysis and subsequent optimization presented in this paper.
R Komanduri - One of the best experts on this subject based on the ideXlab platform.
-
thermal analysis of laser surface transformation hardening optimization of process parameters
International Journal of Machine Tools & Manufacture, 2004Co-Authors: R Komanduri, Zhen Bing HouAbstract:Abstract This paper deals with the optimization of process parameters for maximum productivity (given by the product of scanning velocity and cross feed) in laser transformation hardening. The process parameters considered are laser beam power, P ; laser beam diameter, D b ; and the Heat Intensity distribution, namely, normal, bimodal, or uniform. A thermal analysis of the laser surface transformation hardening of gears was conducted (based on Jaeger’s classical moving Heat source method) by considering the laser beam as a moving plane (disc) Heat source to establish the temperature rise distribution in the workpiece (gear) of finite width. In a recent investigation [Int. J. Heat Mass Transfer 44 (2001) 2845], the authors considered the case of a Heat source with a pseudo-Gaussian (or normal) distribution of Heat Intensity. The analytical results were compared with the experimental results published in the literature. In laser Heat treatment of steel, it is generally considered preferable to use a wider Heat Intensity distribution, such as uniform or bimodal, for it enables more uniform case hardening depth. In this paper, this model is extended to cover bimodal and uniform distributions and compared with the normal distribution. Scanning velocities for no surface melting and for a case hardening depth of 0.1 mm were determined for surface transformation hardening of AISI 1036 (EN 8) steel for a range of laser beam powers, P , laser beam diameters, D b , and various Heat Intensity distributions. Since diffusion during the Heat treatment (surface transformation hardening) process is a time dependent phenomenon, based on the literature review, an interaction time of 15 ms was taken as a basis. It is hoped that laser industry with adequate facilities available can validate the thermal analysis and subsequent optimization presented in this paper.
-
Thermal analysis of laser surface transformation hardening—optimization of process parameters
International Journal of Machine Tools and Manufacture, 2004Co-Authors: R Komanduri, Zhen Bing HouAbstract:Abstract This paper deals with the optimization of process parameters for maximum productivity (given by the product of scanning velocity and cross feed) in laser transformation hardening. The process parameters considered are laser beam power, P ; laser beam diameter, D b ; and the Heat Intensity distribution, namely, normal, bimodal, or uniform. A thermal analysis of the laser surface transformation hardening of gears was conducted (based on Jaeger’s classical moving Heat source method) by considering the laser beam as a moving plane (disc) Heat source to establish the temperature rise distribution in the workpiece (gear) of finite width. In a recent investigation [Int. J. Heat Mass Transfer 44 (2001) 2845], the authors considered the case of a Heat source with a pseudo-Gaussian (or normal) distribution of Heat Intensity. The analytical results were compared with the experimental results published in the literature. In laser Heat treatment of steel, it is generally considered preferable to use a wider Heat Intensity distribution, such as uniform or bimodal, for it enables more uniform case hardening depth. In this paper, this model is extended to cover bimodal and uniform distributions and compared with the normal distribution. Scanning velocities for no surface melting and for a case hardening depth of 0.1 mm were determined for surface transformation hardening of AISI 1036 (EN 8) steel for a range of laser beam powers, P , laser beam diameters, D b , and various Heat Intensity distributions. Since diffusion during the Heat treatment (surface transformation hardening) process is a time dependent phenomenon, based on the literature review, an interaction time of 15 ms was taken as a basis. It is hoped that laser industry with adequate facilities available can validate the thermal analysis and subsequent optimization presented in this paper.
-
Analysis of Heat partition and temperature distribution in sliding systems
Wear, 2001Co-Authors: R Komanduri, Z B HouAbstract:Analytical solutions were developed for the temperature rise distribution for the classical case of a tribological sliding system due to frictional Heat source at the interface. The sliding system is approximated initially to an infinitely long band Heat source with uniform distribution of Heat Intensity. Since the partition coefficient between the stationary and the moving bodies (relative to the Heat source) is not a constant but varies along the interface, variable Heat partition along the interface was considered using the functional analysis approach. In this method, the temperature distribution at all points along the interface between the two bodies is matched closely and the functions of the Heat partition fractions at the interface as well as the temperature distribution in the two bodies (both on the sliding interface as well as with respect to depth) are determined.
-
general solutions for stationary moving plane Heat source problems in manufacturing and tribology
International Journal of Heat and Mass Transfer, 2000Co-Authors: Z B Hou, R KomanduriAbstract:Abstract General solutions (both transient and steady state) for the temperature rise at any point due to stationary/moving plane Heat sources of different shapes (elliptical, circular, rectangular, and square) and Heat Intensity distributions (uniform, parabolic, and normal) are presented using the Jaeger’s classical Heat source method (J.C. Jaeger, Moving sources of Heat and the temperature at sliding contacts, Proc. Royal Society of NSW 76 (1942) 203–224). Starting from an instantaneous point Heat source solution, an elliptical moving Heat source with different Heat Intensity distributions, namely, uniform, parabolic and normal, was used as the basic plane Heat source and its solution for the temperature rise at any point was derived. This analysis was then extended to other plane Heat sources, such as circular, rectangular, and square Heat sources to cover a range of manufacturing processes and tribological problems experienced in engineering practice. In addition, the analysis presented here is valid for both transient and steady state conditions while most analyses to date are strictly for quasi-steady state conditions. The solutions for the stationary Heat sources are obtained from the moving Heat source solution by simply equating the velocity of sliding to zero. Further, the analysis can be used to determine the temperature distribution not only at the surface but also with respective to the depth which again is a very important consideration in most manufacturing and tribological applications since it effects the subsurface deformation, metallurgical changes, hardness variation, and residual stresses. It can also be used to determine the maximum and average temperatures within the area of the Heat source. Thus, the analysis presented here is believed to be comprehensive.
-
General solutions for stationary/moving plane Heat source problems in manufacturing and tribology
International Journal of Heat and Mass Transfer, 2000Co-Authors: Z B Hou, R KomanduriAbstract:Abstract General solutions (both transient and steady state) for the temperature rise at any point due to stationary/moving plane Heat sources of different shapes (elliptical, circular, rectangular, and square) and Heat Intensity distributions (uniform, parabolic, and normal) are presented using the Jaeger’s classical Heat source method (J.C. Jaeger, Moving sources of Heat and the temperature at sliding contacts, Proc. Royal Society of NSW 76 (1942) 203–224). Starting from an instantaneous point Heat source solution, an elliptical moving Heat source with different Heat Intensity distributions, namely, uniform, parabolic and normal, was used as the basic plane Heat source and its solution for the temperature rise at any point was derived. This analysis was then extended to other plane Heat sources, such as circular, rectangular, and square Heat sources to cover a range of manufacturing processes and tribological problems experienced in engineering practice. In addition, the analysis presented here is valid for both transient and steady state conditions while most analyses to date are strictly for quasi-steady state conditions. The solutions for the stationary Heat sources are obtained from the moving Heat source solution by simply equating the velocity of sliding to zero. Further, the analysis can be used to determine the temperature distribution not only at the surface but also with respective to the depth which again is a very important consideration in most manufacturing and tribological applications since it effects the subsurface deformation, metallurgical changes, hardness variation, and residual stresses. It can also be used to determine the maximum and average temperatures within the area of the Heat source. Thus, the analysis presented here is believed to be comprehensive.
Richard A. Fenske - One of the best experts on this subject based on the ideXlab platform.
-
Increased hospital admissions associated with extreme-Heat exposure in King County, Washington, 1990–2010
Reviews on Environmental Health, 2015Co-Authors: Tania Busch Isaksen, Michael G. Yost, You Ren, Hilary Lyons, Elizabeth K. Hom, Richard A. FenskeAbstract:AbstractIncreased morbidity and mortality have been associated with extreme Heat events, particularly in temperate climates. Few epidemiologic studies have considered the impact of extreme Heat events on hospitalization rates in the Pacific Northwest region. This study quantifies the historic (May to September 1990–2010) Heat-morbidity relationship in the most populous Pacific Northwest County, King County, Washington. A relative risk (RR) analysis was used to explore the association between Heat and all non-traumatic hospitalizations on 99th percentile Heat days, whereas a time series analysis using a piecewise linear model approximation was used to estimate the effect of Heat Intensity on hospitalizations, adjusted for temporal trends and day of the week. A non-statistically significant 2% [95% CI: 1.02 (0.98, 1.05)] increase in hospitalization risk, on a Heat day vs. a non-Heat day, was noted for all-ages and all non-traumatic causes. When considering the effect of Heat Intensity on admissions, we found a statistically significant 1.59% (95% CI: 0.9%, 2.29%) increase in admissions per degree increase in humidex above 37.4°C. Admissions stratified by cause and age produced statistically significant results with both relative risk and time series analyses for nephritis and nephrotic syndromes, acute renal failure, and natural Heat exposure hospitalizations. This study demonstrates that Heat, expressed as humidex, is associated with increased hospital admissions. When stratified by age and cause of admission, the non-elderly age groups (<85 years) experience significant risk for nephritis and nephrotic syndromes, acute renal failure, natural Heat exposure, chronic obstructive pulmonary disease, and asthma hospitalizations.
-
Increased hospital admissions associated with extreme-Heat exposure in King County, Washington, 1990-2010.
Reviews on environmental health, 2015Co-Authors: Tania Busch Isaksen, Michael G. Yost, Elizabeth Hom, You Ren, Hilary Lyons, Richard A. FenskeAbstract:Increased morbidity and mortality have been associated with extreme Heat events, particularly in temperate climates. Few epidemiologic studies have considered the impact of extreme Heat events on hospitalization rates in the Pacific Northwest region. This study quantifies the historic (May to September 1990-2010) Heat-morbidity relationship in the most populous Pacific Northwest County, King County, Washington. A relative risk (RR) analysis was used to explore the association between Heat and all non-traumatic hospitalizations on 99th percentile Heat days, whereas a time series analysis using a piecewise linear model approximation was used to estimate the effect of Heat Intensity on hospitalizations, adjusted for temporal trends and day of the week. A non-statistically significant 2% [95% CI: 1.02 (0.98, 1.05)] increase in hospitalization risk, on a Heat day vs. a non-Heat day, was noted for all-ages and all non-traumatic causes. When considering the effect of Heat Intensity on admissions, we found a statistically significant 1.59% (95% CI: 0.9%, 2.29%) increase in admissions per degree increase in humidex above 37.4°C. Admissions stratified by cause and age produced statistically significant results with both relative risk and time series analyses for nephritis and nephrotic syndromes, acute renal failure, and natural Heat exposure hospitalizations. This study demonstrates that Heat, expressed as humidex, is associated with increased hospital admissions. When stratified by age and cause of admission, the non-elderly age groups (
Tania Busch Isaksen - One of the best experts on this subject based on the ideXlab platform.
-
Increased hospital admissions associated with extreme-Heat exposure in King County, Washington, 1990–2010
Reviews on Environmental Health, 2015Co-Authors: Tania Busch Isaksen, Michael G. Yost, You Ren, Hilary Lyons, Elizabeth K. Hom, Richard A. FenskeAbstract:AbstractIncreased morbidity and mortality have been associated with extreme Heat events, particularly in temperate climates. Few epidemiologic studies have considered the impact of extreme Heat events on hospitalization rates in the Pacific Northwest region. This study quantifies the historic (May to September 1990–2010) Heat-morbidity relationship in the most populous Pacific Northwest County, King County, Washington. A relative risk (RR) analysis was used to explore the association between Heat and all non-traumatic hospitalizations on 99th percentile Heat days, whereas a time series analysis using a piecewise linear model approximation was used to estimate the effect of Heat Intensity on hospitalizations, adjusted for temporal trends and day of the week. A non-statistically significant 2% [95% CI: 1.02 (0.98, 1.05)] increase in hospitalization risk, on a Heat day vs. a non-Heat day, was noted for all-ages and all non-traumatic causes. When considering the effect of Heat Intensity on admissions, we found a statistically significant 1.59% (95% CI: 0.9%, 2.29%) increase in admissions per degree increase in humidex above 37.4°C. Admissions stratified by cause and age produced statistically significant results with both relative risk and time series analyses for nephritis and nephrotic syndromes, acute renal failure, and natural Heat exposure hospitalizations. This study demonstrates that Heat, expressed as humidex, is associated with increased hospital admissions. When stratified by age and cause of admission, the non-elderly age groups (<85 years) experience significant risk for nephritis and nephrotic syndromes, acute renal failure, natural Heat exposure, chronic obstructive pulmonary disease, and asthma hospitalizations.
-
Increased hospital admissions associated with extreme-Heat exposure in King County, Washington, 1990-2010.
Reviews on environmental health, 2015Co-Authors: Tania Busch Isaksen, Michael G. Yost, Elizabeth Hom, You Ren, Hilary Lyons, Richard A. FenskeAbstract:Increased morbidity and mortality have been associated with extreme Heat events, particularly in temperate climates. Few epidemiologic studies have considered the impact of extreme Heat events on hospitalization rates in the Pacific Northwest region. This study quantifies the historic (May to September 1990-2010) Heat-morbidity relationship in the most populous Pacific Northwest County, King County, Washington. A relative risk (RR) analysis was used to explore the association between Heat and all non-traumatic hospitalizations on 99th percentile Heat days, whereas a time series analysis using a piecewise linear model approximation was used to estimate the effect of Heat Intensity on hospitalizations, adjusted for temporal trends and day of the week. A non-statistically significant 2% [95% CI: 1.02 (0.98, 1.05)] increase in hospitalization risk, on a Heat day vs. a non-Heat day, was noted for all-ages and all non-traumatic causes. When considering the effect of Heat Intensity on admissions, we found a statistically significant 1.59% (95% CI: 0.9%, 2.29%) increase in admissions per degree increase in humidex above 37.4°C. Admissions stratified by cause and age produced statistically significant results with both relative risk and time series analyses for nephritis and nephrotic syndromes, acute renal failure, and natural Heat exposure hospitalizations. This study demonstrates that Heat, expressed as humidex, is associated with increased hospital admissions. When stratified by age and cause of admission, the non-elderly age groups (
Patrick Haggard - One of the best experts on this subject based on the ideXlab platform.
-
No temporal contrast enhancement of simple decreases in noxious Heat
Journal of neurophysiology, 2019Co-Authors: Brianna Beck, Sahana Gnanasampanthan, Gian Domenico Iannetti, Patrick HaggardAbstract:Previous research suggested that a small decrease in noxious Heat Intensity feels surprisingly large because of sensory enhancement of noxious stimulus offsets (a simplified form of “offset analges...
