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排序方式: 共有230条查询结果,搜索用时 31 毫秒
131.
In this article the calculation of brightness and flux for two insertion devices of the 2.8 GeV X‐ray storage ring at the NSLS is discussed. The radiation properties from the X25 linearly polarized wiggler and the new X25 short‐period undulator are compared at a fixed photon energy (11.3 keV) corresponding to emission from the fifth harmonic of the short‐period undulator. For this computation, three commonly available synchrotron radiation programs are used. The capabilities of each of these codes are briefly discussed, and their range of applicability are commented on. It is concluded that special care is needed when modeling the radiation of the classes of insertion devices considered here. 相似文献
132.
波荡器是基于自由电子激光的小型THz源关键器件, 其可调节的周期性磁场结构与两端的光腔配合, 使得穿越的电子束产生带增益的相干辐射, 最终达到THz源所需要的功率. 同纯永磁结构相比, 混合型波荡器通过软铁材料调节由永磁块磁化方向性差异导致的磁场分布误差, 同时可提供更高的场强. 本文针对小型THz源需求, 对混合型波荡器进行了相关物理设计. 在解析方法分析的基础上, 采用OPERA3D/TOSCA有限元分析软件, 对波荡器进行了三维磁场数值模拟和积分场优化. 通过对波荡器端部结构的调整, 优化后模型的一次场积分(导向误差)小于0.01Gs﹒m, 电子轨迹偏移小于0.02mm. 相似文献
133.
134.
Andrei Marcus 《Algebras and Representation Theory》2001,4(1):25-54
We study Rickard equivalences between p-blocks of twisted group algebras and their local structure, in connection with Dade's conjectures. We prove that an extended form of Broué's conjecture implies Dade's Inductive Conjecture in the Abelian defect group case; this is a consequence of the fact that Rickard equivalences induced by complexes of graded bimodules preserve the relevant Clifford theoretical invariants. As an application, we show that these conjectures hold for p-extensions of blocks with cyclic defect groups. 相似文献
135.
The Structure of Hopf Algebras with a Weak Projection 总被引:2,自引:0,他引:2
Peter Schauenburg 《Algebras and Representation Theory》2000,3(3):187-211
We analyze the structure of a Hopf algebra H that has a Hopf subalgebra H " and a left H "-module coalgebra projection onto H ". In this situation H H " Q for Q = H / H "+
H, and the Hopf algebra structure on H can be recovered from suitable structures on Q, among others an in general nonassociative multiplication. The construction of H from H " and Q generalizes Radford biproduct, double crossproducts, and certain bicrossproducts. Further examples are Hopf algebras with a triangular decomposition, like all quantized enveloping algebras. In an appendix, we improve a standard criterion for a bicrossproduct A
B of two Hopf algebras to be a Hopf algebra, and we show that in this case the antipode of the bicrossproduct is bijective if the antipodes of the factors are. 相似文献
136.
Shuanhong Wang Dingguo Wang Zhongping Yao 《Southeast Asian Bulletin of Mathematics》2000,24(1):105-113
The smash coproduct coalgebra has been generalized to crossed coproduct coalgebra in [3]. It is natural to replace the smash coproduct by the crossed coproduct and consider the conditions under which the smash product algebra structure and the crossed coproduct coalgebra structure will inherit a bialgebra structure or a Hopf algebra structure. We derive necessary and sufficient conditions for this problem. This generalizes the corresponding results in [7]. Finally, we characterize this new structure by introducing a concept of (H, )-comodule and prove that Heisenberg double [4] and smash coproduct do not make a bialgebra.AMS Subject Classification (1991): 16S40 16W30The first and second authors were partially supported by NNSF of China. The first author was also supported by the NSF of Henan Province and the second author by the YSF of Shandong Province (No. Q98A05113). 相似文献
137.
138.
合成了三种基于1-吗啉基-3-咪唑基丙烷异核双阳离子的新型二磺酸功能化BrΦsted酸性离子液体:1-[4-(4-磺酸丁基)吗啉基-3-[3-(4-磺酸丁基)咪唑基]丙烷二(三氟甲烷磺酸)盐{A,[(C4SO3H)m(C4SO3H)i]p(OTf)2}、1-[4-(4-磺酸丁基)吗啉基-3-[3-(4-磺酸丁基)咪唑基]丙烷二硫酸氢盐{B,[(C4SO3H)m(C4SO3H)i]p(HSO4)2}及1-[4-(4-磺酸丁基)吗啉基-3-[3-(4-磺酸丁基)咪唑基]丙烷二磷酸二氢盐{C,[(C4SO3H)m(C4SO3H)i]p(H2PO4)2}.其结构经FT-IR、MS、NMR等确认.选择吗啉、甲基咪唑单磺酸功能化离子液体作为对照组,以苯甲醛与环己酮之间的交叉Aldol缩合反应考察了其催化活性.用Hammett方法测定了其酸性,实验结果表明,所合成的三种双磺酸功能化离子液体的催化能力比单磺酸功能化离子液体的强,其酸性次序与催化活性相一致.其中,阴离子为三氟甲烷磺酸根的离子液体对18种Aldol缩合反应底物有极好的适应性,并且催化活性最强,产率高达90%,在重复使用10次后,仍保持较高的反应活性.关键词二磺酸功能化离子液体;合成;催化活性;Hammett方法;交叉Aldol缩合反应;重复使用 相似文献
139.
Given a closed ideal I in a C*-algebra A, an ideal J (not necessarily closed) in I , a *-homomorphism α : A → M(I ) and a map L : J → A with some properties, based on earlier works of Pimsner and Katsura, we define a C*-algebra
which we call the Crossed Product by a Partial Endomorphism. We introduce the Crossed Product by a Partial Endomorphism
induced by a local homeomorphism σ : U → X where X is a compact Hausdorff space and U is an open subset of X. A bijection between the gauge invariant ideals of
and the σ, σ-1- invariant open subsets of X is showed. If (X, σ) has the property that
is topologically free for each closed σ, σ-1-invariant subset X′ of X then we obtain a bijection between the ideals of
and the open σ, σ-1-invariant subsets of X.
*Partially supported by CNPq.
**Supported by CNPq. 相似文献
140.
This paper has studied the barium spectra in external magnetic and
electric fields on the recently-built system based on a
super-conducting solenoid with high stability of better than 1 Gauss.
Firstly, we compared the spectra in a high pure magnetic field of
$B=4.00000$\,T for different polarized laser, $\sigma^{+}$ and
$\sigma^-$. We prove that after a proper shift, the $\sigma^+$ and
$\sigma^-$ spectra are completely identical. We also investigated the
dependence of the spectral feature in the high magnetic field on an
additionally applied crossing electric field. Along with the increase
of the electric field, there is an energy shift for every spectral
line. Based on a transformative Hamiltonian, we explained this energy
shift well. 相似文献