This study investigated the microstructural characteristics, metallurgy, microhardness, and tensile strength of AZ31 and AZ61 magnesium alloy weldments, fabricated in a CO2 laser welding process with the adjustment of...This study investigated the microstructural characteristics, metallurgy, microhardness, and tensile strength of AZ31 and AZ61 magnesium alloy weldments, fabricated in a CO2 laser welding process with the adjustment of various parameters. The results show that the AZ31 weldment contains equiaxed grains within the fusion zone （FZ）. By contrast, the FZ of the AZ61 weldment contains refined cellular grains and the partially melted zone （PMZ） contains bulk grains. We infer that the difference in aluminum content between the two magne-sium alloys results in different supercooling rates and solid grain structures. For both weldments, the ultimate tensile strength （UTS） de-creases following the CO2 laser welding process. However, no significant difference is noted between the UTS of the two weldments, sug-gesting that tensile strength is insensitive to the Al content of the magnesium alloy. The CO2 laser welding process is shown to increase the microhardness of both magnesium alloys. Furthermore, grain refinement is responsible for the maximum hardness in the FZ of both weld-ments. The AZ61 weldment has a higher content of Al, resulting in a greater grain refinement.展开更多
Variations between earthquakes result in many factors that influence post-earthquake building damage(e.g.,ground motion parameters,building structure,site information,and quality of construction).Consequently,it is ne...Variations between earthquakes result in many factors that influence post-earthquake building damage(e.g.,ground motion parameters,building structure,site information,and quality of construction).Consequently,it is necessary to develop an appropriate building damage-rate estimation model.The building damage survey data were recorded and constructed into files by the Architecture and Building Research Institute(ABRI),Taiwan for the 1999 Chi-Chi earthquake in the Nantou region as a basis for developing a building damage rate estimation model by applying fuzzy theory to express the fragility curves of buildings as a membership function.Empirical verification was performed using post-earthquake building damage data in the Taichung city that suffered relatively severe damage.Results indicate that fuzzy theory can be applied to predict building damage rates and that the estimated results are similar to actual disaster figures.Prediction of disaster damage using building damage rates can provide a reference for immediate disaster response during earthquakes and for regular disaster prevention and rescue planning.展开更多
In this study, we made references to past literatures and developed an e-learning training program for CSL （Chinese as a Second Language） teachers. The class was held from July to August, 2010, in Chinese Culture Un...In this study, we made references to past literatures and developed an e-learning training program for CSL （Chinese as a Second Language） teachers. The class was held from July to August, 2010, in Chinese Culture University （Taiwan）, and we designed a performance-evaluation questionnaire with the Delphi method. Three months after the training program was completed, the questionnaire was given to the 30 students of the class, and they were asked to answer questions regarding their use of e-learning in the actual practice. We also asked 5 teachers to conduct experimental e-learning for us to video-record and observe. This effort allows us to discuss the use of e-learning among CSL teachers in Taiwan, come up with a conclusion and suggestions, and use the findings as references for course-planning and policies or research regarding the digital learning of Chinese.展开更多
This study aims to develop a framework based on the Nadal formula to assess train derailment risk. Monte Carlo simulation was adopted to develop 10000 sets of random parameters to assess train derailment risk subject ...This study aims to develop a framework based on the Nadal formula to assess train derailment risk. Monte Carlo simulation was adopted to develop 10000 sets of random parameters to assess train derailment risk subject to the curvature radius of the track, the difference between the flange angle and the equivalent conicity, and accelerations from 250 to 989.22 gal during horizontal earthquake. The results indicated that railway in Taiwan, China has no derailment risk under normal conditions. However, when earthquakes occur, the derailment risk increases with the unloading factor which is caused by seismic force. The results also show that equivalent conicity increases derailment risk;as a result, equivalent conicity should be listed as one of maintenance priorities. In addition, among all train derailment factors, flange angle, equivalent conicity and unload factors are the most significant ones.展开更多
To estimate nutrient budgets,water samples were collected at 16 sites in Tapong lagoon from January 2004 through April 2005 and the parameters of water quality were analyzed immediately after collection.These data wer...To estimate nutrient budgets,water samples were collected at 16 sites in Tapong lagoon from January 2004 through April 2005 and the parameters of water quality were analyzed immediately after collection.These data were used to build a box model for calculating nutrient budgets of the lagoon.We estimated the net amount of nutrient fluxes into (coming from creeks) and out (from tidal inlet) of the lagoon and calculated the total amount of nutrient that deposits into the sediment in a full tidal cycle.During January and April,nutrients (including nitrate,nitrite and ammonia) accumulated in the lagoon,but phosphate,total phosphate and suspended solids were flushed out of the lagoon from the tidal inlet.In addition,a huge amount of suspended solids (13-15 tons per tidal cycle) flew from the lagoon to the adjacent ocean through the inlet-outlet channel.展开更多
文摘This study investigated the microstructural characteristics, metallurgy, microhardness, and tensile strength of AZ31 and AZ61 magnesium alloy weldments, fabricated in a CO2 laser welding process with the adjustment of various parameters. The results show that the AZ31 weldment contains equiaxed grains within the fusion zone （FZ）. By contrast, the FZ of the AZ61 weldment contains refined cellular grains and the partially melted zone （PMZ） contains bulk grains. We infer that the difference in aluminum content between the two magne-sium alloys results in different supercooling rates and solid grain structures. For both weldments, the ultimate tensile strength （UTS） de-creases following the CO2 laser welding process. However, no significant difference is noted between the UTS of the two weldments, sug-gesting that tensile strength is insensitive to the Al content of the magnesium alloy. The CO2 laser welding process is shown to increase the microhardness of both magnesium alloys. Furthermore, grain refinement is responsible for the maximum hardness in the FZ of both weld-ments. The AZ61 weldment has a higher content of Al, resulting in a greater grain refinement.
基金Project(93-2625-Z-027-006)supported by the National Science Council of Taipei,China
文摘Variations between earthquakes result in many factors that influence post-earthquake building damage(e.g.,ground motion parameters,building structure,site information,and quality of construction).Consequently,it is necessary to develop an appropriate building damage-rate estimation model.The building damage survey data were recorded and constructed into files by the Architecture and Building Research Institute(ABRI),Taiwan for the 1999 Chi-Chi earthquake in the Nantou region as a basis for developing a building damage rate estimation model by applying fuzzy theory to express the fragility curves of buildings as a membership function.Empirical verification was performed using post-earthquake building damage data in the Taichung city that suffered relatively severe damage.Results indicate that fuzzy theory can be applied to predict building damage rates and that the estimated results are similar to actual disaster figures.Prediction of disaster damage using building damage rates can provide a reference for immediate disaster response during earthquakes and for regular disaster prevention and rescue planning.
文摘In this study, we made references to past literatures and developed an e-learning training program for CSL （Chinese as a Second Language） teachers. The class was held from July to August, 2010, in Chinese Culture University （Taiwan）, and we designed a performance-evaluation questionnaire with the Delphi method. Three months after the training program was completed, the questionnaire was given to the 30 students of the class, and they were asked to answer questions regarding their use of e-learning in the actual practice. We also asked 5 teachers to conduct experimental e-learning for us to video-record and observe. This effort allows us to discuss the use of e-learning among CSL teachers in Taiwan, come up with a conclusion and suggestions, and use the findings as references for course-planning and policies or research regarding the digital learning of Chinese.
文摘This study aims to develop a framework based on the Nadal formula to assess train derailment risk. Monte Carlo simulation was adopted to develop 10000 sets of random parameters to assess train derailment risk subject to the curvature radius of the track, the difference between the flange angle and the equivalent conicity, and accelerations from 250 to 989.22 gal during horizontal earthquake. The results indicated that railway in Taiwan, China has no derailment risk under normal conditions. However, when earthquakes occur, the derailment risk increases with the unloading factor which is caused by seismic force. The results also show that equivalent conicity increases derailment risk;as a result, equivalent conicity should be listed as one of maintenance priorities. In addition, among all train derailment factors, flange angle, equivalent conicity and unload factors are the most significant ones.
基金supported by "Dapeng Bay National Science Area Administration"
文摘To estimate nutrient budgets,water samples were collected at 16 sites in Tapong lagoon from January 2004 through April 2005 and the parameters of water quality were analyzed immediately after collection.These data were used to build a box model for calculating nutrient budgets of the lagoon.We estimated the net amount of nutrient fluxes into (coming from creeks) and out (from tidal inlet) of the lagoon and calculated the total amount of nutrient that deposits into the sediment in a full tidal cycle.During January and April,nutrients (including nitrate,nitrite and ammonia) accumulated in the lagoon,but phosphate,total phosphate and suspended solids were flushed out of the lagoon from the tidal inlet.In addition,a huge amount of suspended solids (13-15 tons per tidal cycle) flew from the lagoon to the adjacent ocean through the inlet-outlet channel.
