多束速调管的增益带宽

 研究了M个束、N个共振腔的多束速调管(MBK)的增益和带宽，得到了描述小信号增益和带宽与器件结构参数和电子束参数关系的公式，给出了在不同参数下增益随频率的变化曲线。分析了多腔对增益，多束对带宽的影响。计算结果表明：多腔可以提高增益；多束可以降低Q值，从而可以增中带宽，带宽增加工了3.6%，还可以提高增益；对于MBK，频率交叉调谐对增加带宽不如频率调谐好；空间电荷波只对增益有影响，对带宽没有影响。最后，预估一种L带多束速调管的增益带宽为8.1%。     

Application of directed metallation in synthesis. Part 3: Studies in the synthesis of (±)-semivioxanthin and its analogues

The synthesis of several analogues of (±)-semivioxanthin including five thiophene analogues, using directed metalation are reported. The strategy consisted of the synthesis of functionalized naphthalene or benzo[b]thiophene as building blocks followed by annelation of the pyrone.     

Asymptotic Correction of More Sturm–Liouville Eigenvalue Estimates

The asymptotic correction technique of Paine, de Hoog and Anderssen can dramatically improve the accuracy of finite difference or finite element eigenvalues at negligible extra cost if closed form expressions are available for the errors in a simpler related problem. This paper gives closed form expressions for the errors in the eigenvalues of certain Sturm–Liouville problems obtained by various methods, thereby increasing the range of problems for which asymptotic correction can achieve maximum efficiency. It also investigates implementation of the method for more general problems.     

非因子化方法研究D~+→ ■~0K~+衰变(英文)

在领头阶和αs 修正阶 ,用QCD因子化方法 ,并对它的软胶子效应用光锥QCD求和规则分析D+ → K0 K+ 衰变过程 ,我们分析发现朴素因子化方法的结果远离实验结果 ,QCD因子化方法结果靠近实验结果 ,但是 ,在QCD因子化方法中 ,若考虑软胶子效应 ,其结果与实验结果相一致 .另外 ,计算发现 ,软胶子效应在该衰变道中有相当大的贡献 ,因此不能被忽略     

Notes on Sublattice-Lattices

We prove that directly reducible lattices and selfdual subdirectly irreducible lattices of locally finite length are determined by their sublattice-lattices. As a corollary we obtain that splitting varieties are closed under the isomorphism of sublattice-lattices iff they are selfdual. A class of selfdual non-closed varieties is given too.     

一个非协调膜元的高精度分析

本文讨论一个四自由度三角形非协调膜元的整体超收敛性，外推和亏量校正。     

Generalized Christoffel functions and error of positive quadrature

The author gives some upper and lower bounds for the generalized Christoffel functions related to a Ditzian-Totik generalized weight. As an application, an error estimate of Gauss quadrature formula inL ₁-weighted norm is derived.Dedicated to Prof. Luigi Gatteschi on the occasion of his 70th birthdayWork sponsored by MURST 40%.     

Cyclic reduction and FACR methods for piecewise hermite bicubic orthogonal spline collocation

Cyclic reduction and Fourier analysis-cyclic reduction (FACR) methods are presented for the solution of the linear systems which arise when orthogonal spline collocation with piecewise Hermite bicubics is applied to boundary value problems for certain separable partial differential equations on a rectangle. On anN×N uniform partition, the cyclic reduction and Fourier analysis-cyclic reduction methods requireO(N ²log₂ N) andO(N ²log₂log₂ N) arithmetic operations, respectively.     

Trefftz,collocation, and other boundary methods—A comparison

In this article we survey the Trefftz method (TM), the collocation method (CM), and the collocation Trefftz method (CTM). We also review the coupling techniques for the interzonal conditions, which include the indirect Trefftz method, the original Trefftz method, the penalty plus hybrid Trefftz method, and the direct Trefftz method. Other boundary methods are also briefly described. Key issues in these algorithms, including the error analysis, are addressed. New numerical results are reported. Comparisons among TMs and other numerical methods are made. It is concluded that the CTM is the simplest algorithm and provides the most accurate solution with the best numerical stability. © 2006 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007     

局部环上正交群中一类子群的扩群

定出了局部环上正交群中一类子群的扩群,得到了如下结果:设R是局部环,M是R的唯一极大理想,O(2m,R)为R上正交群.对R的任意理想S,G(2m,S)表示子群{A BC D∈O(2m,R)|B∈Sm×m}.如果char(R)≠2,m≥3,G(2m,0)≤X≤G(2m,M),那么存在R的理想S,使得X=G(2m,S).