A novel crystal characterization instrument has been built up in which a combination of X-ray multiple diffraction and X-ray topography is applied to enabling the cross-correlation between micro-crystallographic symme...A novel crystal characterization instrument has been built up in which a combination of X-ray multiple diffraction and X-ray topography is applied to enabling the cross-correlation between micro-crystallographic symmetry and its spatial dependence in relation to lattice defects. This facility is used to examine, in a self-consistent manner, growth sector-dependant changes to both the crystallographic structure and the lattice defects associated with the action of habit-modifying additives in a number of representative crystal growth systems. In addition, the new instrument can be used to probe micro-crystallographic aspects(such as distortion to crystal symmetry) and relate these in a spatially resolved manner to the crystal defect structure in crystals doped with known habit modifiers.展开更多
Effects of multiple strengthening treatments （i.e. ag mechanical properties and stability of nanoscale prec in this research. Various tests such as hardness, tensi ng either at three or four consecutive temperatures...Effects of multiple strengthening treatments （i.e. ag mechanical properties and stability of nanoscale prec in this research. Various tests such as hardness, tensi ng either at three or four consecutive temperatures） on pitated phases in an AA2090 alloy have been evaluated e, electrical resistance, differential scanning calorimetric （DSC）, and transmission electron microscopy （TEM） have been performed. The results show that the ultimate tensile strength （UTS） and the yield strength of the samples aged at four consecutive temperatures （i.e. natural aging＋190℃＋150℃＋100℃） can be increased approximately to 660 and 610 MPa, respectively. It is also found that precipitation of T1 phase occurs during multiple aging process of the alloy and the higher amounts of enthalpies shown in DSC charts are linked to higher volume fraction of this precipitate. Furthermore, TEM observations reveal that T1 phase has plate shape morphology and its crystal structure is in the form of hcp with lattice parameters of a=0.467 nm and c=0.878 nm.展开更多
A new distribution scheme of decryption keys used in optical verification systems is proposed. The encryption procedure is digitally implemented with the use of an iteration algorithm in computer. Three target images ...A new distribution scheme of decryption keys used in optical verification systems is proposed. The encryption procedure is digitally implemented with the use of an iteration algorithm in computer. Three target images corresponding to three wavelengths are encoded into three sets of phase-only masks （POMs） by a special distributing method. These three sets of POMs are assigned to three authorized users as the personal identification. A lensless optical system is used as the verification system. In the verification procedure, every two of the three authorized users can pass the verification procedure cooperatively, but only one user cannot do. Numerical simulation shows that the proposed distribution scheme of decryption keys not only can improve the security level of verification system, but also can bring convenience and flexibility for authorized users.展开更多
To achieve de novo protein structure determination of challenging cases, multi-wavelength anomalous diffraction(MAD) and multiple isomorphous replacement(MIR) phasing can be powerful tools to obtain low-resolution ini...To achieve de novo protein structure determination of challenging cases, multi-wavelength anomalous diffraction(MAD) and multiple isomorphous replacement(MIR) phasing can be powerful tools to obtain low-resolution initial phases from heavy-atom derivative datasets, then phase extension is needed against high-resolution data to obtain accurate structures.In this context, we propose a direct-methods procedure here that could improve the initial low-resolution MAD/MIR phase quality.And accordingly, an automated process for extending initial phases to high resolution is also described.These two procedures are both implanted in the newly released IPCAS pipeline.Three cases are used to perform the test, including one set of 4.17 ? MAD data from a membrane protein and two sets of MAD/MIR data with derivatives truncated down to 6.80 ? and 6.90 ?, respectively.All the results have shown that the initial phases generated from the direct-methods procedure are better than that from the conventional MAD/MIR methods.The automated phase extensions for the latter two cases starting from 6.80 ? to 3.00 ? and 6.90 ? to 2.80 ? are proved to be successful, leading to complete models.This may provide convenient and reliable tools for phase improvement and phase extension in difficult low-resolution tasks.展开更多
A set of coupled wave equations of acoustooptic diffraction with multiple acoustic waves along different directions is put forward and its solutions are derived. The characteristics of the diffraction efficiency, com ...A set of coupled wave equations of acoustooptic diffraction with multiple acoustic waves along different directions is put forward and its solutions are derived. The characteristics of the diffraction efficiency, com -pression, cross modulation, and intermodulation intensities are analyzed theoretically. The theoretical results are supported by experimental measurements through our new multiple directional acoustooptic devices.展开更多
柔性交流输电装置(flexible AC transmission system,FACTS)在提升电网安全稳定和运行效率方面发挥了重要的作用,研究多FACTS控制器间的交互影响及协调控制方法具有重要的现实意义。研究多静态同步补偿器(staticsynchronous compensator...柔性交流输电装置(flexible AC transmission system,FACTS)在提升电网安全稳定和运行效率方面发挥了重要的作用,研究多FACTS控制器间的交互影响及协调控制方法具有重要的现实意义。研究多静态同步补偿器(staticsynchronous compensator,STATCOM)在提升系统阻尼方面的协调控制问题,并针对多个STATCOM阻尼控制器之间存在的负交互影响,提出一种基于模式自适应直接搜索(mesh adaptive direct search,MADS)算法的多STATCOM阻尼控制器协调控制方法,该方法使用频域设计思想保证了控制器多运行方式下的鲁棒性,同时使用MADS算法保证多控制器的协调运行能力,最终实现多台STATCOM阻尼控制器的协调运行与控制。仿真结果验证了该方法的正确性以及在实际电网中应用的可行性。展开更多
基金Supported by EPSRC,the UK Research Council(No. GRIR 6 5 787)
文摘A novel crystal characterization instrument has been built up in which a combination of X-ray multiple diffraction and X-ray topography is applied to enabling the cross-correlation between micro-crystallographic symmetry and its spatial dependence in relation to lattice defects. This facility is used to examine, in a self-consistent manner, growth sector-dependant changes to both the crystallographic structure and the lattice defects associated with the action of habit-modifying additives in a number of representative crystal growth systems. In addition, the new instrument can be used to probe micro-crystallographic aspects(such as distortion to crystal symmetry) and relate these in a spatially resolved manner to the crystal defect structure in crystals doped with known habit modifiers.
文摘Effects of multiple strengthening treatments （i.e. ag mechanical properties and stability of nanoscale prec in this research. Various tests such as hardness, tensi ng either at three or four consecutive temperatures） on pitated phases in an AA2090 alloy have been evaluated e, electrical resistance, differential scanning calorimetric （DSC）, and transmission electron microscopy （TEM） have been performed. The results show that the ultimate tensile strength （UTS） and the yield strength of the samples aged at four consecutive temperatures （i.e. natural aging＋190℃＋150℃＋100℃） can be increased approximately to 660 and 610 MPa, respectively. It is also found that precipitation of T1 phase occurs during multiple aging process of the alloy and the higher amounts of enthalpies shown in DSC charts are linked to higher volume fraction of this precipitate. Furthermore, TEM observations reveal that T1 phase has plate shape morphology and its crystal structure is in the form of hcp with lattice parameters of a=0.467 nm and c=0.878 nm.
文摘A new distribution scheme of decryption keys used in optical verification systems is proposed. The encryption procedure is digitally implemented with the use of an iteration algorithm in computer. Three target images corresponding to three wavelengths are encoded into three sets of phase-only masks （POMs） by a special distributing method. These three sets of POMs are assigned to three authorized users as the personal identification. A lensless optical system is used as the verification system. In the verification procedure, every two of the three authorized users can pass the verification procedure cooperatively, but only one user cannot do. Numerical simulation shows that the proposed distribution scheme of decryption keys not only can improve the security level of verification system, but also can bring convenience and flexibility for authorized users.
基金Project supported by the National Basic Research Program of China(Grant No.2011CB911100)of the Ministry of Science and Technology of China
文摘To achieve de novo protein structure determination of challenging cases, multi-wavelength anomalous diffraction(MAD) and multiple isomorphous replacement(MIR) phasing can be powerful tools to obtain low-resolution initial phases from heavy-atom derivative datasets, then phase extension is needed against high-resolution data to obtain accurate structures.In this context, we propose a direct-methods procedure here that could improve the initial low-resolution MAD/MIR phase quality.And accordingly, an automated process for extending initial phases to high resolution is also described.These two procedures are both implanted in the newly released IPCAS pipeline.Three cases are used to perform the test, including one set of 4.17 ? MAD data from a membrane protein and two sets of MAD/MIR data with derivatives truncated down to 6.80 ? and 6.90 ?, respectively.All the results have shown that the initial phases generated from the direct-methods procedure are better than that from the conventional MAD/MIR methods.The automated phase extensions for the latter two cases starting from 6.80 ? to 3.00 ? and 6.90 ? to 2.80 ? are proved to be successful, leading to complete models.This may provide convenient and reliable tools for phase improvement and phase extension in difficult low-resolution tasks.
基金The project is supported by National Natural Science Foundation of China.
文摘A set of coupled wave equations of acoustooptic diffraction with multiple acoustic waves along different directions is put forward and its solutions are derived. The characteristics of the diffraction efficiency, com -pression, cross modulation, and intermodulation intensities are analyzed theoretically. The theoretical results are supported by experimental measurements through our new multiple directional acoustooptic devices.
文摘柔性交流输电装置(flexible AC transmission system,FACTS)在提升电网安全稳定和运行效率方面发挥了重要的作用,研究多FACTS控制器间的交互影响及协调控制方法具有重要的现实意义。研究多静态同步补偿器(staticsynchronous compensator,STATCOM)在提升系统阻尼方面的协调控制问题,并针对多个STATCOM阻尼控制器之间存在的负交互影响,提出一种基于模式自适应直接搜索(mesh adaptive direct search,MADS)算法的多STATCOM阻尼控制器协调控制方法,该方法使用频域设计思想保证了控制器多运行方式下的鲁棒性,同时使用MADS算法保证多控制器的协调运行能力,最终实现多台STATCOM阻尼控制器的协调运行与控制。仿真结果验证了该方法的正确性以及在实际电网中应用的可行性。
