衍射法细丝直径的精密测量

分析了激光衍射法测量细丝直径技术中影响精度的几个主要因素，研究了一种微弱衍射条纹的精密处理及识别技术，有效地提高了测量精度，实测结果表明，文中讨论的技术能在１０￣５０μｍ的范围内实现正负０．１μｍ的重复精度，分辨力优于０．０１μｍ。     

Augmenting Trees to Meet Biconnectivity and Diameter Constraints

Given a graph G=(V,E) and a positive integer D , we consider the problem of finding a minimum number of new edges E' such that the augmented graph G'=(V,E\cup E') is biconnected and has diameter no greater than D. In this note we show that this problem is NP-hard for all fixed D , by employing a reduction from the DOMINATING SET problem. We prove that the problem remains NP-hard even for forests and trees, but in this case we present approximation algorithms with worst-case bounds 3 (for even D ) and 6 (for odd D ). A closely related problem of finding a minimum number of edges such that the augmented graph has diameter no greater than D has been shown to be NP-hard by Schoone et al. [21] when D=3 , and by Li et al. [17] when D=2. Received April 19, 1999; revised June 5, 2001.     

Diameter NASREQ协议在卫星移动通信系统中的应用研究

如何对接入网络的用户进行身份认证、授予相应权限并进行计费,是卫星移动通信系统网络管理需解决的重要问题。简要介绍认证、授权、计费(AAA)的基本概念,分析Diameter协议框架、协议原理以及协议应用于网络接入的特点。阐述协议中包含的各种应用,给出Diameter NASREQ应用的一种系统模型。重点研究Diameter NASREQ协议在卫星移动通信系统中的应用,详述应用中客户机和服务器中各模块的功能和工作原理。通过分析,说明该应用的可行性及有效性。     

Highly ordered anodic alumina nanotemplate with about 14 nm diameter

A novel method for the fabrication of highly ordered nanopore arrays with very small diameter of 14 nm was demonstrated by using low-temperature anodization. Two-step anodization was carried out at 25 V, sulfuric acid concentration of 0.3 M, and electrolyte temperature of −15 °C. After anodization, a regular pore array with mean diameter of 14 nm and interpore distance of 65 nm was formed. The pore diameter and regular arrangement were confirmed by scanning electron microscopy (SEM) and fast Fourier transformation (FFT), respectively. The present results strongly suggest that the diameter of pores in a highly ordered alumina template can be reduced by lowering the anodization temperature.     

步进电机细分及其在光电测径系统中的应用

叙述了步进电机的细分技术及其测长原理。作为一种测长手段应用于工件直径测量系统中，为提高步进电机细分测长的精度，系统采用了软件补偿的办法，应用光电定位和ＭＣＳ—５１单片机实施控制，构成一种测量范围在１～１００ｍｍ，精度较高，效费比高的光电测径系统。     

倒虹吸管管径计算的迭代法

本文先将倒虹吸管的管径计算公式整理成等式左边只含管径的一次方法，右边含有管径高阶非线性的迭代函数，然后证明该迭代函数收敛，最后利用数学迭代原理给迭代函数右边赋初值，计算左边的管径。继续迭代下去，就能求出倒虹吸管的管径。     

Fast algorithms for computing the diameter of a finite planar set

Three algorithms for computing the diameter of a finite planar set are proposed. Although all three algorithms have (O(n ²) worst-case running time, an expected-complexity analysis shows that, under reasonable probabilistic assumptions, all three algorithms have linear expected running time. Experimental results indicate that two of these algorithms perform very well for some distributions, and are competitive with an existing method. Finally, we exhibit situations where these exact algorithms out-perform a published approximate algorithm.Research of the first author was supported by grant NSERC A 2422. Research of the second author was supported by grants NSERC A 9293, FCAC EQ-1678 and a Killam Senior Research Fellowship awarded by the Canada Council     

内壁激冷气缸套的组织研究

离心铸造气缸套采用内壁激冷新方法，可细化气缸套的内层组织：使硬质相的网孔直径从３级提高到１～２级，石墨片长度从４级提高到６级。实践证明，这种方法不会出现中间夹杂层现象。     

Diameter variability of cycles and tori

The diameter of a graph is an important factor for communication as it determines the maximum communication delay between any pair of processors in a network. Graham and Harary [N. Graham, F. Harary, Changing and unchanging the diameter of a hypercube, Discrete Applied Mathematics 37/38 (1992) 265-274] studied how the diameter of hypercubes can be affected by increasing and decreasing edges. They concerned whether the diameter is changed or remains unchanged when the edges are increased or decreased. In this paper, we modify three measures proposed in Graham and Harary (1992) to include the extent of the change of the diameter. Let D^-k(G) is the least number of edges whose addition to G decreases the diameter by (at least) k, D⁺⁰(G) is the maximum number of edges whose deletion from G does not change the diameter, and D^+k(G) is the least number of edges whose deletion from G increases the diameter by (at least) k. In this paper, we find the values of D^-k(C_m), D^-1(T_m,n), D^-2(T_m,n), D⁺¹(T_m,n), and a lower bound for D⁺⁰(T_m,n) where C_m be a cycle with m vertices, T_m,n be a torus of size m by n.     

一种基于Diameter协议的NAS模型

随着日益复杂的路由器和网络接入服务器大量投入使用,使得当前AAA协议在安全性和稳定性上的缺点日益明显。基于Diameter、EAP和PANA协议,设计了一个础诅接入服务器模型。该模型覆盖了Diameter NASREQ应用和EAP应用、PANA协议中PAA和EP的功能,以及EAP协议中认证者的功能。对原型系统进行了系统测试,测试结果表明,原型系统基本实现了Diameter、EAP和PANA协议对网络接入服务器的要求,具有较好的安全性和稳定性。