The effects of the cutting parameters （cutting speed, feed rate and depth of cut） on the surface roughness in machining the Nimonic C-263 alloy were investigated. The experiments were conducted using Taguchi＇s expe...The effects of the cutting parameters （cutting speed, feed rate and depth of cut） on the surface roughness in machining the Nimonic C-263 alloy were investigated. The experiments were conducted using Taguchi＇s experimental design. The effect of cutting parameters on surface roughness was evaluated and the optimum cutting conditions for minimizing the surface roughness were determined. A second order model was established between the cutting parameters and surface roughness, using the response surface methodology. The experimental results revealed that among the parameters considered, the feed rate is the most significant which influences the surface roughness, followed by the cutting speed. The predicted values and measured values are fairly close, which indicates that the developed model can be effectively used to predict the surface roughness in machining the Nimonic C-263 alloy. The predicted values are validated using the additive law.展开更多
Based on the Pathfinder sea surface temperature(PFSST),the surface axis and its pattern of the Yellow Sea Warm Current(YSWC) are discussed.A structure of double-warm-tongue is found in February and it varies in differ...Based on the Pathfinder sea surface temperature(PFSST),the surface axis and its pattern of the Yellow Sea Warm Current(YSWC) are discussed.A structure of double-warm-tongue is found in February and it varies in different years.Two indexes are calculated to represent the westward shift(WSI) and northward extension(NEI) of the warm water in the Yellow Sea(YS).Wavelet analysis illustrates that the WSI and NEI have prominent periods of 3-6 years and 3-4 years,respectively.The Empirical Orthogonal Function(EOF) decomposition is applied to the winter wind stress curl and the Kuroshio Current(KC) transport,which are believed to play important roles in forcing the variability of the YSWC surface axis.Statistics shows that the WSI is significantly related with the second EOF mode of the wind stress curl in February,which may force the YSWC surface axis moving westward and maintaining the double warm tongues because of its opposite curl in the YSWC domain.The first EOF mode of wind stress curl in January is propitious for inducing the warm tongue in the YS to advance more northward.Hence,the wind stress curls both in January and in February could force variations of the YSWC surface axis;however,the effect of the January wind stress curl is relatively weaker than that of the February.The relationship between the NEI and the KC transport is remarkable,and it seems that the stronger KC supplies more power to push the YSWC northward against the southward wind.展开更多
Boron nitride （BN） films for high-frequency surface acoustic wave （SAW） devices are deposited on Ti/AI/Si（111） wafers by radio frequency （RF） magnetron sputtering. The structure of BN films is investigated by ...Boron nitride （BN） films for high-frequency surface acoustic wave （SAW） devices are deposited on Ti/AI/Si（111） wafers by radio frequency （RF） magnetron sputtering. The structure of BN films is investigated by Fourier transform infrared （FrlR） spectroscopy and X-ray diffraction （XRD） spectra, and the surface morphology and piezoelectric properties of BN films are characterized by atomic force microscopy （AFM）. The results show that when the flow ratio of nitrogen and argon is 2：18, the cubic BN （c-BN） film is deposited with high purity and c-axis orientation, and when the flow ratio of nitrogen and argon is 4：20, the hexagonal BN （h-BN） film is deposited with high c-axis orientation. Both particles are uniform and compact, and the roughnesses are 1.5 nm and 2.29 nm, respectively. The h-BN films have better piezoelectric response and distribu- tion than the c-BN films.展开更多
文摘The effects of the cutting parameters （cutting speed, feed rate and depth of cut） on the surface roughness in machining the Nimonic C-263 alloy were investigated. The experiments were conducted using Taguchi＇s experimental design. The effect of cutting parameters on surface roughness was evaluated and the optimum cutting conditions for minimizing the surface roughness were determined. A second order model was established between the cutting parameters and surface roughness, using the response surface methodology. The experimental results revealed that among the parameters considered, the feed rate is the most significant which influences the surface roughness, followed by the cutting speed. The predicted values and measured values are fairly close, which indicates that the developed model can be effectively used to predict the surface roughness in machining the Nimonic C-263 alloy. The predicted values are validated using the additive law.
基金Supported by the National Basic Research Program of China (973 Program) (No 2005C B422308)the National High-tech Research and Development Program (863 Program) (No 2006AA09Z149)the China International Science and Technology Cooperation Program (No2006DFB21250)
文摘Based on the Pathfinder sea surface temperature(PFSST),the surface axis and its pattern of the Yellow Sea Warm Current(YSWC) are discussed.A structure of double-warm-tongue is found in February and it varies in different years.Two indexes are calculated to represent the westward shift(WSI) and northward extension(NEI) of the warm water in the Yellow Sea(YS).Wavelet analysis illustrates that the WSI and NEI have prominent periods of 3-6 years and 3-4 years,respectively.The Empirical Orthogonal Function(EOF) decomposition is applied to the winter wind stress curl and the Kuroshio Current(KC) transport,which are believed to play important roles in forcing the variability of the YSWC surface axis.Statistics shows that the WSI is significantly related with the second EOF mode of the wind stress curl in February,which may force the YSWC surface axis moving westward and maintaining the double warm tongues because of its opposite curl in the YSWC domain.The first EOF mode of wind stress curl in January is propitious for inducing the warm tongue in the YS to advance more northward.Hence,the wind stress curls both in January and in February could force variations of the YSWC surface axis;however,the effect of the January wind stress curl is relatively weaker than that of the February.The relationship between the NEI and the KC transport is remarkable,and it seems that the stronger KC supplies more power to push the YSWC northward against the southward wind.
基金supported by the National Natural Science Foundation of China (Nos.50972105 and 60806030)the Tianjin Natural Science Foundation (Nos. 09JCZDJC16500 and 08JCYBJC14600)
文摘Boron nitride （BN） films for high-frequency surface acoustic wave （SAW） devices are deposited on Ti/AI/Si（111） wafers by radio frequency （RF） magnetron sputtering. The structure of BN films is investigated by Fourier transform infrared （FrlR） spectroscopy and X-ray diffraction （XRD） spectra, and the surface morphology and piezoelectric properties of BN films are characterized by atomic force microscopy （AFM）. The results show that when the flow ratio of nitrogen and argon is 2：18, the cubic BN （c-BN） film is deposited with high purity and c-axis orientation, and when the flow ratio of nitrogen and argon is 4：20, the hexagonal BN （h-BN） film is deposited with high c-axis orientation. Both particles are uniform and compact, and the roughnesses are 1.5 nm and 2.29 nm, respectively. The h-BN films have better piezoelectric response and distribu- tion than the c-BN films.
