The effects of Yb content on the microstructures and mechanical properties of 2519A aluminum alloy plate were investigated by means of tensile test,optical microscopy,transmission electron microscopy,scanning electron...The effects of Yb content on the microstructures and mechanical properties of 2519A aluminum alloy plate were investigated by means of tensile test,optical microscopy,transmission electron microscopy,scanning electron microscopy and X-ray diffractometer.The results show that addition of 0.17% (mass fraction) Yb increases the density of θ' particles of the 2519A alloy plate and reduces the coarsening speed rate of θ' phase at 300 ℃.Therefore,tensile strength is enhanced from 483.2 MPa to 501.0 MPa at room temperature and is improved from 139.5 MPa to 169.4 MPa at 300 ℃.The results also show that with the addition of 0.30% (mass fraction) Yb,the mechanical properties increase at 300 ℃ and decrease at room temperature.With Yb additions,the Al7.4Cu9.6Yb2 phase is found whilst the segregated phases of as-cast alloys along grain boundaries become discontinuous,thin and spheroidized.展开更多
With volume size increasing, it is necessary to develop a highly efficient compression algorithm, which is suitable for progressive refinement between the data server and the browsing client. For three-dimensional lar...With volume size increasing, it is necessary to develop a highly efficient compression algorithm, which is suitable for progressive refinement between the data server and the browsing client. For three-dimensional large volume data, an efficient hierarchical algorithm based on wavelet compression was presented, using intra-band dependencies of wavelet coefficients. Firstly, after applying blockwise hierarchical wavelet decomposition to large volume data, the block significance map was obtained by using one bit to indicate significance or insignificance of the block. Secondly, the coefficient block was further subdivided into eight sub-blocks if any significant coefficient existed in it, and the process was repeated, resulting in an incomplete octree. One bit was used to indicate significance or insignificance, and only significant coefficients were stored in the data stream. Finally, the significant coefficients were quantified and compressed by arithmetic coding. The experimental results show that the proposed algorithm achieves good compression ratios and is suited for random access of data blocks. The results also show that the proposed algorithm can be applied to progressive transmission of 3D volume data.展开更多
Two micromachined solenoid-type inductors with different electroplated core structures, ellipse and rectangle, were fabricated, tested and compared in order to reach optimum designs for integrated induetoes and transf...Two micromachined solenoid-type inductors with different electroplated core structures, ellipse and rectangle, were fabricated, tested and compared in order to reach optimum designs for integrated induetoes and transformers. In the process of fabrication, UV-LIGA, dry. etching technique, fine polishing and eleetroplating techniques have been adopted to achieve high performance mieminduetor. Experimental results show that both types of the induetors are characterized by high inductance, Q-factor and low electrical resistance. While the inductance of the inductor with rectangular magnetic core is slightly higher than that with elliptical magnetic core, the quality factor of the latter is larger than that of the former.展开更多
A model of nonlinear differential systems with impulsive effect on random moments is considered. The extensions of qualitative analysis of the model is mainly focused on and three modified sufficient conditions are pr...A model of nonlinear differential systems with impulsive effect on random moments is considered. The extensions of qualitative analysis of the model is mainly focused on and three modified sufficient conditions are presented about p-moment boundedness in the process by Liapunov method with nonlinear item dependent on the impulsive effects, which may gain wider use in industrial engineering, physics, etc. At last, an example is given to show an theoretical application of the obtained results.展开更多
Motivated by the recent biomimic design of microstructured adhesive surfaces,we study adhesion between a film-terminated fibrillar array and a rigid substrate.Using a two-dimensional model and ignoring the deformation...Motivated by the recent biomimic design of microstructured adhesive surfaces,we study adhesion between a film-terminated fibrillar array and a rigid substrate.Using a two-dimensional model and ignoring the deformation of the fibers and the backing layer,we show that the adhesion behavior is dominated by a dimensionless parameter reflecting the global flexibility of the terminal film.In particular,if the parameter is larger than 0.4,the adhesion is reversible;otherwise one or more hysteresis loops will appear after an approach-retraction cycle,leading to significant increase in the specific separation work.The result is expected to help not only optimal design of the structure,but also other applications such as micro-manipulation in micromechanical systems.展开更多
基金Project(2005CB623700) supported by the National Basic Research Program of China
文摘The effects of Yb content on the microstructures and mechanical properties of 2519A aluminum alloy plate were investigated by means of tensile test,optical microscopy,transmission electron microscopy,scanning electron microscopy and X-ray diffractometer.The results show that addition of 0.17% (mass fraction) Yb increases the density of θ' particles of the 2519A alloy plate and reduces the coarsening speed rate of θ' phase at 300 ℃.Therefore,tensile strength is enhanced from 483.2 MPa to 501.0 MPa at room temperature and is improved from 139.5 MPa to 169.4 MPa at 300 ℃.The results also show that with the addition of 0.30% (mass fraction) Yb,the mechanical properties increase at 300 ℃ and decrease at room temperature.With Yb additions,the Al7.4Cu9.6Yb2 phase is found whilst the segregated phases of as-cast alloys along grain boundaries become discontinuous,thin and spheroidized.
基金Supported by Natural Science Foundation of China (No. 60373061).
文摘With volume size increasing, it is necessary to develop a highly efficient compression algorithm, which is suitable for progressive refinement between the data server and the browsing client. For three-dimensional large volume data, an efficient hierarchical algorithm based on wavelet compression was presented, using intra-band dependencies of wavelet coefficients. Firstly, after applying blockwise hierarchical wavelet decomposition to large volume data, the block significance map was obtained by using one bit to indicate significance or insignificance of the block. Secondly, the coefficient block was further subdivided into eight sub-blocks if any significant coefficient existed in it, and the process was repeated, resulting in an incomplete octree. One bit was used to indicate significance or insignificance, and only significant coefficients were stored in the data stream. Finally, the significant coefficients were quantified and compressed by arithmetic coding. The experimental results show that the proposed algorithm achieves good compression ratios and is suited for random access of data blocks. The results also show that the proposed algorithm can be applied to progressive transmission of 3D volume data.
基金Supported by High Technology. Research and Development Program （No. 2004AA302042）, the Nanotechnology Program of Shanghai Science ＆ Technology Committee （No. 0352nm014）, the National Natural Science Foundation of China （No. 50275096）, Samsung Advanced Institute of Technology. （SALT）, Sansung Electronics Co., Ltd., and Shanghai-Applied Materials Research and Development Fund （No.0515）.
文摘Two micromachined solenoid-type inductors with different electroplated core structures, ellipse and rectangle, were fabricated, tested and compared in order to reach optimum designs for integrated induetoes and transformers. In the process of fabrication, UV-LIGA, dry. etching technique, fine polishing and eleetroplating techniques have been adopted to achieve high performance mieminduetor. Experimental results show that both types of the induetors are characterized by high inductance, Q-factor and low electrical resistance. While the inductance of the inductor with rectangular magnetic core is slightly higher than that with elliptical magnetic core, the quality factor of the latter is larger than that of the former.
基金The Special Research Funds for Young Col-lege Teacher of Shanghai (No. 355877)
文摘A model of nonlinear differential systems with impulsive effect on random moments is considered. The extensions of qualitative analysis of the model is mainly focused on and three modified sufficient conditions are presented about p-moment boundedness in the process by Liapunov method with nonlinear item dependent on the impulsive effects, which may gain wider use in industrial engineering, physics, etc. At last, an example is given to show an theoretical application of the obtained results.
基金supported by the National Basic Research Program of China (Grant No. 2011CB302101)PhD Programs Foundation of the Ministry of Education of China (Grant No. 20113402110005)
文摘Motivated by the recent biomimic design of microstructured adhesive surfaces,we study adhesion between a film-terminated fibrillar array and a rigid substrate.Using a two-dimensional model and ignoring the deformation of the fibers and the backing layer,we show that the adhesion behavior is dominated by a dimensionless parameter reflecting the global flexibility of the terminal film.In particular,if the parameter is larger than 0.4,the adhesion is reversible;otherwise one or more hysteresis loops will appear after an approach-retraction cycle,leading to significant increase in the specific separation work.The result is expected to help not only optimal design of the structure,but also other applications such as micro-manipulation in micromechanical systems.
