On CNC commuting contractive tuples

The characteristic function has been an important tool for studying completely non-unitary contractions on Hilbert spaces. In this note, we consider completely non-coisometric contractive tuples of commuting operators on a Hilbert space H. We show that the characteristic function, which is now an operator-valued analytic function on the open Euclidean unit ball in ℂⁿ, is a complete unitary invariant for such a tuple. We prove that the characteristic function satisfies a natural transformation law under biholomorphic mappings of the unit ball. We also characterize all operator-valued analytic functions which arise as characteristic functions of pure commuting contractive tuples.     

Fast Multiplication on Elliptic Curves over Small Fields of Characteristic Two

We discuss new algorithms for multiplying points on elliptic curves defined over small finite fields of characteristic two. This algorithm is an extension of previous results by Koblitz, Meier, and Staffelbach. Experimental results show that the new methods can give a running time improvement of up to 50 % compared with the ordinary binary algorithm for multiplication. Finally, we present a table of elliptic curves, which are well suited for elliptic curve public key cryptosystems, and for which the new algorithm can be used. Received 14 January 1997 and revised 4 September 1997     

3分贝高功率电桥

本文简述了3分贝高功率带状线电桥的设计方法,分析了其功率容量及提高功率容量的措施,讨论了在无大功率设备条件下,如何进行击穿试验。     

水泵变频运行的图解分析方法

本文以图解的方式分析了水泵变频运行时的特性曲线，以及水泵并联运行时的特性，为水泵变频运行时的节能分析和计算提供了一种简易的分析方法。     

THE SUM OF DEFICIENCIES OF ENTIRE FUNCTION ON C~n

This paper proves that: Let / be an entire function of finite order λon Cn. Then(1) , where k(X) is a nonnegative constant depending only on A;(2) If (a, f) = 1, then A is a positive integer and equals the lower order of /.     

硅基波导、光探测器和CMOS电路的集成

对于集成光学器件和微电子电路制作，应用了驻波监控指示技术（ＳＷＡＭＩ）、局部氧化技术（ＬＯＣＯＳ）、光波导和探测器的平接、漏波，以及镜耦合技术。文章介绍了硅基光波导、光探测器和ＣＭＯＳ电路的单片集成技术。讨论了集成工艺以及静态和动态测量结果     

Characteristic impedance of meshed-strip line

The characteristic impedances of meshed-strip lines are obtained by conformal mapping. The results are in good agreement with measured data.This work was supported by the National Natural Science Fundation of China.     

任意横截面形状非均匀介质波导传输特性的分析

用阶梯近似与边缘元和模匹配相结合的方法分析了一大类任意横截面形状非均匀介质波导的传输特性，将非均匀部分用一系列级联的台阶近似，各台阶用微波多模网络等效，用边缘元方法求得各本地波导的本征值问题后，用模匹配法算 出各微波网络的散射参数，最后通过级联的微波网络求得融洽上非均匀结构的传输特性，由于边缘元方法的通用性，此法可对各种不同横截面形状的非均匀介质波导进行分析。     

Zero-free regions for multivariate Tutte polynomials (alias Potts-model partition functions) of graphs and matroids

The chromatic polynomial P_G(q) of a loopless graph G is known to be non-zero (with explicitly known sign) on the intervals (−∞,0), (0,1) and (1,32/27]. Analogous theorems hold for the flow polynomial of bridgeless graphs and for the characteristic polynomial of loopless matroids. Here we exhibit all these results as special cases of more general theorems on real zero-free regions of the multivariate Tutte polynomial Z_G(q,v). The proofs are quite simple, and employ deletion–contraction together with parallel and series reduction. In particular, they shed light on the origin of the curious number 32/27.