The feasibility of semi-solid die casting of ADC12 aluminum alloy was studied.The effects of plunger speed, gate thickness, and solid fraction of the slurry on the defects were determined.The defects investigated are ...The feasibility of semi-solid die casting of ADC12 aluminum alloy was studied.The effects of plunger speed, gate thickness, and solid fraction of the slurry on the defects were determined.The defects investigated are gas and shrinkage porosity.In the experiments, semi-solid slurry was prepared by the gas-induced semi-solid (GISS) technique.Then, the slurry was transferred to the shot sleeve and injected into the die.The die and shot sleeve temperatures were kept at 180 °C and 250 °C, respectively.The results show that the samples produced by the GISS die casting give little porosity, no blister and uniform microstructure.From all the results, it can be concluded that the GISS process is feasible to apply in the ADC12 aluminum die casting process.In addition, the GISS process can give improved properties such as decreased porosity and increased microstructure uniformity.展开更多
The gas induced semi-solid(GISS) is a rheocasting process that produces semi-solid slurry by applying fine gas bubble injection through a graphite diffuser.The process is developed to be used in the die casting indust...The gas induced semi-solid(GISS) is a rheocasting process that produces semi-solid slurry by applying fine gas bubble injection through a graphite diffuser.The process is developed to be used in the die casting industry.To apply the GISS process with a die casting process,a GISS maker unit is designed and attached to a conventional die casting machine with little modifications.The commercial parts are developed and produced by the GISS die casting process.The GISS die casting shows the feasibility to produce industrial parts with aluminum 7075 and A356 with lower porosity than liquid die casting.展开更多
The gas induced semi-solid(GISS) process was developed to create semi-solid slurry with fine and uniform globular structure.The combination of local rapid heat extraction and vigorous agitation by the injection of fin...The gas induced semi-solid(GISS) process was developed to create semi-solid slurry with fine and uniform globular structure.The combination of local rapid heat extraction and vigorous agitation by the injection of fine inert gas bubbles through a graphite diffuser in molten metal held at a temperature above its liquidus temperature changes the morphology of primary α(Al) from coarse dendritic to rosette-like and finally to fine globular.The GISS process produced semi-solid slurry at low solid fractions and then formed the slurry by a squeeze casting process to produce casting parts.The effects of primary phase morphology on the mechanical properties of Al-Si-Mg-Fe alloy were investigated.The results show that the ultimate tensile strength and elongation are affected by the shape factor and particle size of the primary α(Al).展开更多
An aluminum extrusion process is mainly used to fabricate long tubes, beams and rods for various applications.However, this process has a high production cost due to the need for investment of high-pressure machinery....An aluminum extrusion process is mainly used to fabricate long tubes, beams and rods for various applications.However, this process has a high production cost due to the need for investment of high-pressure machinery.The objective of this work is to develop a new semi-solid extrusion process using semi-solid slurry at low solid fractions.A laboratory extrusion system was used to fabricate aluminum rods with the diameter of 12 mm.The semi-solid metal process used in this study was the gas induced semi-solid (GISS) technique.To study the feasibility of the GISS extrusion process, the effects of extrusion parameters such as plunger speed and solid fraction on the extrudability, microstructure, and mechanical properties of extruded samples were investigated.The results show that the plunger speed and solid fraction of the semi-solid metal need to be carefully controlled to produce complete extruded parts.展开更多
The NASA Goddard Institute for Space Studies (GISS) coupled global climatemodel was used to investigate the sensitivity of sea ice to improved representations of sea-iceradiative processes: (1) a more sophisticated su...The NASA Goddard Institute for Space Studies (GISS) coupled global climatemodel was used to investigate the sensitivity of sea ice to improved representations of sea-iceradiative processes: (1) a more sophisticated surface albedo scheme and (2) the penetration of solarradiation in sea ice. The results show that the large-scale sea-ice conditions are very sensitiveto the aforementioned parameteriza-tions. Although the more sophisticated surface albedo schemeproduces a more realistic seasonal cycle of the surface albedo as compared with the baselinesimulation, the resulting higher albedo relative to the baseline simulation generates much more andthicker ice in the arctic. The penetration of solar radiation in sea-ice itself tends to reduce theice cover and thickness in the entire arctic and the western antarctic, and increase the ice coverand thickness in the eastern antarctic. The combination of (1) and (2) significantly improves thesimulations of the average ice thickness and its spatial distribution in the arctic. The atmosphericresponses associated with sea-ice changes were also discussed. While improvements are seen,particularly of the ice thickness distribution, there are still some unrealistic aspects that willrequire further improvements to the sea-ice component.展开更多
In recent years, as there has been a major change in the necessity and importance of sightseeing information, a platform to provide real-time sightseeing information according to the ever-changing circumstances is nec...In recent years, as there has been a major change in the necessity and importance of sightseeing information, a platform to provide real-time sightseeing information according to the ever-changing circumstances is necessary. Additionally, it is effective to adopt gamification to increase users’ motivation to continuously utilize the system in order to provide them with more information. In the present study, in order to support users’ enjoyment in creating efficient and pleasant sightseeing plans, the system that incorporates gamification to increase motivation was developed combining with web-geographic information systems (Web-GIS) and sightseeing planning and sharing system. The system was operated over a period of 2 weeks in Chofu City, Tokyo Metropolis, Japan. Based on the results of a questionnaire survey for 51 users, though the operability of the 3 main functions incorporated with motivation by gamification was rated lower than those of the 2 basic functions, their usefulness was highly rated. Based on the results of the access log analysis, it was effective to design the system so that the same functions can be used regardless of the type of information terminal. Additionally, it was evident that the continuous utilization of the system could increase the number of sightseeing plans created by the users.展开更多
The crop area estimaton is one of the main fields in application of remotesensing. The paper focuses on the operational method for rice planting areaestimation, in which TM datu is used to ertract base rice area in a ...The crop area estimaton is one of the main fields in application of remotesensing. The paper focuses on the operational method for rice planting areaestimation, in which TM datu is used to ertract base rice area in a given year of1992. The NOAA AVHRR data is used to prwhct the changing tendency of the nceplanting area. The base area data needs to be updated for every rice growth penodupon the availability of TM data. Three methods can be used to extract the base riceplanting area. They are (1) visual interpretation with interaedve adjustmant on thescreen, (2) iflteraCtive automatic classification with manual elinunating of the non-rice pixels on the screen, and (3) automatic dassification with GIS spatial analysis.These methods can be combined to increase reliability and accuracy. The currentpaper is only concemed with the description of the second method. MultitemporalNOAA AVHRR SAVI data are combined as multiband image and are classifiedusing supetwsed makimum likelihood classifier on ERDAS to prediCt the changingtendency of rice planting area. The method has been successfully used in extraCtingearly nce area in Hubei Province in 1994 and acceptable result was obtained.展开更多
基金funded by the Royal Golden Jubilee Ph.D. Program (Grant No.PHD/0173/2550)the Thai Research Fund (Contract number MRG5280215)Prince of Songkla University (Contract No.AGR530031M)
文摘The feasibility of semi-solid die casting of ADC12 aluminum alloy was studied.The effects of plunger speed, gate thickness, and solid fraction of the slurry on the defects were determined.The defects investigated are gas and shrinkage porosity.In the experiments, semi-solid slurry was prepared by the gas-induced semi-solid (GISS) technique.Then, the slurry was transferred to the shot sleeve and injected into the die.The die and shot sleeve temperatures were kept at 180 °C and 250 °C, respectively.The results show that the samples produced by the GISS die casting give little porosity, no blister and uniform microstructure.From all the results, it can be concluded that the GISS process is feasible to apply in the ADC12 aluminum die casting process.In addition, the GISS process can give improved properties such as decreased porosity and increased microstructure uniformity.
基金supports from Prince of Songkla University (No.AGR530031M)the Royal Golden Jubilee Ph.D program (No.PHD/0173/2550)
文摘The gas induced semi-solid(GISS) is a rheocasting process that produces semi-solid slurry by applying fine gas bubble injection through a graphite diffuser.The process is developed to be used in the die casting industry.To apply the GISS process with a die casting process,a GISS maker unit is designed and attached to a conventional die casting machine with little modifications.The commercial parts are developed and produced by the GISS die casting process.The GISS die casting shows the feasibility to produce industrial parts with aluminum 7075 and A356 with lower porosity than liquid die casting.
文摘The gas induced semi-solid(GISS) process was developed to create semi-solid slurry with fine and uniform globular structure.The combination of local rapid heat extraction and vigorous agitation by the injection of fine inert gas bubbles through a graphite diffuser in molten metal held at a temperature above its liquidus temperature changes the morphology of primary α(Al) from coarse dendritic to rosette-like and finally to fine globular.The GISS process produced semi-solid slurry at low solid fractions and then formed the slurry by a squeeze casting process to produce casting parts.The effects of primary phase morphology on the mechanical properties of Al-Si-Mg-Fe alloy were investigated.The results show that the ultimate tensile strength and elongation are affected by the shape factor and particle size of the primary α(Al).
基金the financial supports from Prince of Songkla University (Contract number AGR530031M)
文摘An aluminum extrusion process is mainly used to fabricate long tubes, beams and rods for various applications.However, this process has a high production cost due to the need for investment of high-pressure machinery.The objective of this work is to develop a new semi-solid extrusion process using semi-solid slurry at low solid fractions.A laboratory extrusion system was used to fabricate aluminum rods with the diameter of 12 mm.The semi-solid metal process used in this study was the gas induced semi-solid (GISS) technique.To study the feasibility of the GISS extrusion process, the effects of extrusion parameters such as plunger speed and solid fraction on the extrudability, microstructure, and mechanical properties of extruded samples were investigated.The results show that the plunger speed and solid fraction of the semi-solid metal need to be carefully controlled to produce complete extruded parts.
基金supported by the NASA polar program and National Natural Science Foundation of China under contract Nos 40233032 and 40376006.
文摘The NASA Goddard Institute for Space Studies (GISS) coupled global climatemodel was used to investigate the sensitivity of sea ice to improved representations of sea-iceradiative processes: (1) a more sophisticated surface albedo scheme and (2) the penetration of solarradiation in sea ice. The results show that the large-scale sea-ice conditions are very sensitiveto the aforementioned parameteriza-tions. Although the more sophisticated surface albedo schemeproduces a more realistic seasonal cycle of the surface albedo as compared with the baselinesimulation, the resulting higher albedo relative to the baseline simulation generates much more andthicker ice in the arctic. The penetration of solar radiation in sea-ice itself tends to reduce theice cover and thickness in the entire arctic and the western antarctic, and increase the ice coverand thickness in the eastern antarctic. The combination of (1) and (2) significantly improves thesimulations of the average ice thickness and its spatial distribution in the arctic. The atmosphericresponses associated with sea-ice changes were also discussed. While improvements are seen,particularly of the ice thickness distribution, there are still some unrealistic aspects that willrequire further improvements to the sea-ice component.
文摘In recent years, as there has been a major change in the necessity and importance of sightseeing information, a platform to provide real-time sightseeing information according to the ever-changing circumstances is necessary. Additionally, it is effective to adopt gamification to increase users’ motivation to continuously utilize the system in order to provide them with more information. In the present study, in order to support users’ enjoyment in creating efficient and pleasant sightseeing plans, the system that incorporates gamification to increase motivation was developed combining with web-geographic information systems (Web-GIS) and sightseeing planning and sharing system. The system was operated over a period of 2 weeks in Chofu City, Tokyo Metropolis, Japan. Based on the results of a questionnaire survey for 51 users, though the operability of the 3 main functions incorporated with motivation by gamification was rated lower than those of the 2 basic functions, their usefulness was highly rated. Based on the results of the access log analysis, it was effective to design the system so that the same functions can be used regardless of the type of information terminal. Additionally, it was evident that the continuous utilization of the system could increase the number of sightseeing plans created by the users.
文摘The crop area estimaton is one of the main fields in application of remotesensing. The paper focuses on the operational method for rice planting areaestimation, in which TM datu is used to ertract base rice area in a given year of1992. The NOAA AVHRR data is used to prwhct the changing tendency of the nceplanting area. The base area data needs to be updated for every rice growth penodupon the availability of TM data. Three methods can be used to extract the base riceplanting area. They are (1) visual interpretation with interaedve adjustmant on thescreen, (2) iflteraCtive automatic classification with manual elinunating of the non-rice pixels on the screen, and (3) automatic dassification with GIS spatial analysis.These methods can be combined to increase reliability and accuracy. The currentpaper is only concemed with the description of the second method. MultitemporalNOAA AVHRR SAVI data are combined as multiband image and are classifiedusing supetwsed makimum likelihood classifier on ERDAS to prediCt the changingtendency of rice planting area. The method has been successfully used in extraCtingearly nce area in Hubei Province in 1994 and acceptable result was obtained.
