Counter gravity casting equipments(CGCE) were widely used to produce large thin-walled A357 aluminum alloy components. To improve the pressure control precision of CGCE to get high quality castings, a pressure control...Counter gravity casting equipments(CGCE) were widely used to produce large thin-walled A357 aluminum alloy components. To improve the pressure control precision of CGCE to get high quality castings, a pressure control system based on fuzzy-PID hybrid control technology and the digital assembled valve was developed. The actual pressure tracking experiment results show that the special system by applying PID controller and fuzzy controller to varied phases, is not only able to inherit the small error and good static stability of classical PID control, but also has fuzzy control’s advantage of fully adapting itself to the object. The pressure control error is less than 0.3 kPa. By using this pressure control system, large complex thin-walled A357 aluminum alloy castings with high quality was successfully produced.展开更多
Coptis chinensis Franch, a widely used Traditional Chinese Medicine, shows various kinds of bioactivity. The major active components of the herb are considered to be alkaloids. Thus, preparative separation of these al...Coptis chinensis Franch, a widely used Traditional Chinese Medicine, shows various kinds of bioactivity. The major active components of the herb are considered to be alkaloids. Thus, preparative separation of these alkaloids is critical important for further pharmacology and mechanism studies. In the paper, five alkaloids from C. chinensis were purified by HSCCC using the solvent system composed of chloro-form-metha- nol-water (2:1:1, v/v/v) single prepared. The content of each solvent in solvent system were determined by gas chromatography (GC), then according the ratios of solvents in each phase to prepare the mobile and stationary phase respectively. And a comparative study was carried out between together preparation and single preparation of the solvent system. The purities and recoveries of all the products were over 98.5% and 92%. However, 134 mL chloroform, 336 mL methanol and 452 mL water were saved when the two phase were singled by GC. Our research showed an economical method for separating alkaloids from C. chinensis by HSCCC using the solvent system single prepared by GC.展开更多
A multi-try counter-meshing gears stronglink based on micro electromechanical system （MEMS） technology is introduced, including research, design, couple and fabrication of unique signal （UQS） for some specified fi...A multi-try counter-meshing gears stronglink based on micro electromechanical system （MEMS） technology is introduced, including research, design, couple and fabrication of unique signal （UQS） for some specified fields of information security. The stronglink consists of two groups of metal counter-meshing gears, two pawl/ratchet mechanisms, two driving micromotors and two resetting micromotors. The resetting micromotors make counter-meshing gears withdraw by raising pawls so that the interfered counter-meshing gears will be relieved. The energy-coupling element is a photoelectric sensor with a circular notched plate. The counter-meshing mechanism is fabricated using the ultraviolet-lithographie~ galvanoformung and abformung （UV-LiGA） process and a precision mechanical technique. The stronglink can be tried several times if the correct resetting code is known.展开更多
光伏发电并网规模持续增长,改变了电力系统大扰动后的动态特性。文章建立了计及低电压穿越(Low Voltage Ride Through,LVRT)功能的光伏发电系统机电暂态仿真模型。针对故障后联系阻抗显著增大的光伏弱交流并网系统,分析了光伏低电压穿...光伏发电并网规模持续增长,改变了电力系统大扰动后的动态特性。文章建立了计及低电压穿越(Low Voltage Ride Through,LVRT)功能的光伏发电系统机电暂态仿真模型。针对故障后联系阻抗显著增大的光伏弱交流并网系统,分析了光伏低电压穿越的恢复过程对系统行为特性的影响,揭示了因光伏频繁进入LVRT引起系统电压周期性振荡的机制,分析了相关影响因素,并提出了缓解应对措施。最后,面向西藏中部光伏高渗透实际电网,仿真复现了大扰动后系统振荡现象,验证了应对措施的有效性。展开更多
On the basis of the relationship between the Hamiltonian of spin 1/2 quantum system under control and the energy level structure and transitions, a radio frequency pulse sequence is designed using intuitive and half c...On the basis of the relationship between the Hamiltonian of spin 1/2 quantum system under control and the energy level structure and transitions, a radio frequency pulse sequence is designed using intuitive and half counter-intuitive sequences of pulse to transfer the population of the 3-qubit system coherently. The effectiveness of the designed control sequence is verified through the system simulation experiment of the evolution of state. In principle, the design method of the control pulse sequence proposed can be generalized to use in the quantum systems of higher dimension.展开更多
基金Project(2006CB605202) supported by the Basic Research Development Program of China
文摘Counter gravity casting equipments(CGCE) were widely used to produce large thin-walled A357 aluminum alloy components. To improve the pressure control precision of CGCE to get high quality castings, a pressure control system based on fuzzy-PID hybrid control technology and the digital assembled valve was developed. The actual pressure tracking experiment results show that the special system by applying PID controller and fuzzy controller to varied phases, is not only able to inherit the small error and good static stability of classical PID control, but also has fuzzy control’s advantage of fully adapting itself to the object. The pressure control error is less than 0.3 kPa. By using this pressure control system, large complex thin-walled A357 aluminum alloy castings with high quality was successfully produced.
文摘Coptis chinensis Franch, a widely used Traditional Chinese Medicine, shows various kinds of bioactivity. The major active components of the herb are considered to be alkaloids. Thus, preparative separation of these alkaloids is critical important for further pharmacology and mechanism studies. In the paper, five alkaloids from C. chinensis were purified by HSCCC using the solvent system composed of chloro-form-metha- nol-water (2:1:1, v/v/v) single prepared. The content of each solvent in solvent system were determined by gas chromatography (GC), then according the ratios of solvents in each phase to prepare the mobile and stationary phase respectively. And a comparative study was carried out between together preparation and single preparation of the solvent system. The purities and recoveries of all the products were over 98.5% and 92%. However, 134 mL chloroform, 336 mL methanol and 452 mL water were saved when the two phase were singled by GC. Our research showed an economical method for separating alkaloids from C. chinensis by HSCCC using the solvent system single prepared by GC.
基金the High-Technology Research and Development Program of China (Grant No.863-2003AA404210,the second phase 863-2005AA404250,863-2003AA404210 and the third phase 863-2006AA01Z443)
文摘A multi-try counter-meshing gears stronglink based on micro electromechanical system （MEMS） technology is introduced, including research, design, couple and fabrication of unique signal （UQS） for some specified fields of information security. The stronglink consists of two groups of metal counter-meshing gears, two pawl/ratchet mechanisms, two driving micromotors and two resetting micromotors. The resetting micromotors make counter-meshing gears withdraw by raising pawls so that the interfered counter-meshing gears will be relieved. The energy-coupling element is a photoelectric sensor with a circular notched plate. The counter-meshing mechanism is fabricated using the ultraviolet-lithographie~ galvanoformung and abformung （UV-LiGA） process and a precision mechanical technique. The stronglink can be tried several times if the correct resetting code is known.
文摘光伏发电并网规模持续增长,改变了电力系统大扰动后的动态特性。文章建立了计及低电压穿越(Low Voltage Ride Through,LVRT)功能的光伏发电系统机电暂态仿真模型。针对故障后联系阻抗显著增大的光伏弱交流并网系统,分析了光伏低电压穿越的恢复过程对系统行为特性的影响,揭示了因光伏频繁进入LVRT引起系统电压周期性振荡的机制,分析了相关影响因素,并提出了缓解应对措施。最后,面向西藏中部光伏高渗透实际电网,仿真复现了大扰动后系统振荡现象,验证了应对措施的有效性。
基金supported by the National Natural Science Foundation of China (60774098)the National Key Basic Research Program (2006922004)
文摘On the basis of the relationship between the Hamiltonian of spin 1/2 quantum system under control and the energy level structure and transitions, a radio frequency pulse sequence is designed using intuitive and half counter-intuitive sequences of pulse to transfer the population of the 3-qubit system coherently. The effectiveness of the designed control sequence is verified through the system simulation experiment of the evolution of state. In principle, the design method of the control pulse sequence proposed can be generalized to use in the quantum systems of higher dimension.
