中频数字化及数字式正交解调

本文介绍用数字式下变频法实现中频正交解调的基本原理及主要性能。     

Comments on “Multiphase systolic algorithms for spectraldecomposition” [and reply]

Comments that the paper by Liu and Yao (see ibid., vol.40, no.1, p.190, 1992) presented an efficient algorithm for spectral decomposition, but the parallel algorithm and architecture for the Hessenberg reduction has a problem. The matrix obtained from the unitary similarity transformation is not necessarily a Hessenberg matrix. The authors reply that the Hessenberg reduction described is not in the Hessenberg form. Only the first column is in its proper form. There are many ways to overcome such a problem. One simple way is to use the multiphase rectangular systolic array     

R￣d中Hausdorff维数和packing维数的确定

本文目的在于建立确定Ｒ￣ｄ中Ｈａｕｓｄｏｒｆｆ维数ｄｉｍ和ｐａｃｋｉｎｇ维数Ｄｉｍ的两个命题（定理１和定理２），进而寻求Ｒ￣ｄ中Ｈａｕｓｄｏｒｆｆ维数ｄｉｍ与ｐａｃｋｉｎｇ维数Ｄｉｍ相等的条件；这使得我们能够引入分形测度的测度论定义。     

Molecular weight dependence of diblock copolymer segregation at a polymer/polymer interface

Utilizing forward recoil spectrometry (FRES), we have determined the segregation isotherm which describes the interfacial excess z_i^* of diblock copolymers of poly (d₈-styrene-b-2-vinylpyridine) (dPS-PVP) at the interface between the homopolymers PS and PVP as a function of ?_∞, the volume fraction of diblock copolymer remaining in the host homopolymer. All the samples were analyzed after annealing at temperatures and times sufficient to achieve equilibrium segregation. The effect of the degree of polymerization of both the diblock copolymers and the host homopolymers on the segregation isotherm is investigated. When the degree of polymerization of the homopolymer is much larger than that of the diblock copolymer, the normalized interfacial excess (z_i^*/R_g), where R_g is the radius of gyration of an isolated block copolymer chain, is a universal function of that portion of the block copolymer chemical potential due to chain stretching. The existence of such a universal function is predicted by theory and its form is in good agreement with self-consistent mean field calculations. Using these results, one can predict important aspects of the block copolymer segregation (e.g., the saturation interfacial excess) without recourse to the time-consuming numerical calculations. © 1994 John Wiley & Sons, Inc.     

6to4与ISATAP技术相结合的IPv6网络实现

在IPv4向IPv6过渡期间,多种过渡技术可以互相支持、互相组合使用,以达到互利互助。简要介绍了其中2种隧道技术:6to4技术和ISATAP技术,提出了1种基于两者结合的新型实验网络的实现方案。具体讨论了在Linux下如何组建这种新型实验网络平台,详细阐明了如何配置IPv6主机以及双栈路由器,为IPv4过渡到IPv6提供1个可行的方案。     

放大器En-In噪声模型的完善及其与Rn-Gn噪声模型的关系

目前，微波低噪声放大器设计中采用的Ｒｎ－Ｇｎ噪声模型只适用于高频、窄带和源导纳（Ｇｓ≠０）情况，其应用范围有限，特别是不适用于低频段的低噪声放大器设计。本文对文献［１］提出的Ｅｎ－Ｉｎ噪声模型作了改进，使其不仅适用于高频、窄带，而且也适用于低频、宽带放大器的低噪声设计。进而推导出放大器Ｅｎ－Ｉｎ噪声模型与Ｒｎ－Ｇｎ噪声模型的等价关系，给出放大器Ｅｎ－Ｉｎ噪声模型的测量方法及实测结果。     

激光对望远系统损伤的研究

本文对激光光束通过望远系统后光束的变化进行了分析，并对６倍望远镜进行了激光损伤和破坏的实验研究，实验结果表明，激光对望远系统的损伤破坏主要是热效应所致，损伤破坏的情况与激光的能量，波长，脉冲宽度和望远系统的结构有关。     

Electronic Structure and Magnetic Properties of SmCo7-xZrx

The electronic structure and magnetism of SmCo_7-xZr_x alloy are investigated using the spin-polarized MS-X. method. The results show that a few of electrons are transferred to the Sm(5d⁰) orbital due to orbital hybridization between Sm and Co atoms. The exchange interactions between 3d and 5d electrons are more important than the polarization effects of the conductive electrons, thus it is the main reason resulting in the long-range ferromagnetic order in SmCo_7-xZr_x. The Curie temperature of SmCo_7-xZr_x is generally lower than that of corresponding pure Co, which may be explained by the weaker average coupling strength between Co lattices due to some negative couplings mainly occurring of 2e site. The calculated results for the Sm₅Co₃₂Zr₂ cluster may lead to a better understanding of why SmCo_7-xZr_x is stable phase. Since the spin-up DOS peak of d electrons at E_F arises and the bonding of electrons at E_F strengthens with increasing Zr concentration, which results in the internal energy of the system decrease, the stable ferromagnetic order forms in SmCo_7-xZr_x.     

钕玻璃激光放大器反转粒子数的荧光测定法

本文报道了通过测量钕玻璃激光放大器在一定泵浦功率下的荧光波形的方法,获得放大器中反转粒子数密度随时间的变化关系,进而得到反转粒子数密度达到最大值的时刻的测定方法及实验结果。     

10Gbit/s甚短距离传输系统接收模块研究

本文研究了符合OIF—VSR4—01．0规范的甚短距离（VSR）并行光传输系统转换器集成电路，实现了接收部分转换器集成电路中帧同步、8B／10B解码、12路通道去斜移、检错纠错等模块的设计。在Altera的Stratix GX系列的FPGA上实现了接收部分转换器集成电路。仿真分析的结果表明所设计的各个模块能正确的实现接收部分转换器集成电路的功能，给出了仿真结果。