Influence of oxygen pressure on Nd:LuVO4 films grown by pulsed laser deposition

High quality Nd-doped lutecium vanadate thin films on silica glass substrates were fabricated successfully by using a pulsed laser deposition technique. The properties of the samples were characterized by using X-ray diffraction, Rutherford backscattering, atomic force microscopy (AFM), and prism-coupling measurements. The RBS shows that the ratio of Lu/V in the film is 0.991, which is in good agreement with the target composition. X-ray diffraction results show that the degree of crystal orientation along (2 0 0) increases with increasing oxygen pressure up to 20 Pa. The refractive indices of the films determined with dark-mode prism coupling measurements are slight, smaller than that of the bulk crystal. An optimum 20 Pa oxygen pressure, at which the oxygen was leaked into the chamber as the reactive ambient, was determined.     

移动流媒体业务质量评估及监测方案探讨

文章针对在移动流媒体业务运维中存在的各种难点,深入分析网络现状和业务特性,提出了基于用户体验的质量评价体系,探讨了全程全网的数据采集和分析方案,设计了自动化的业务监测评估工具,为实现对端到端3G数据业务的智能管控和优化做出了有益尝试。     

Signaling Performance Trials and Evaluation Results on a GPRS Platform

Generic Packet Radio Service (GPRS) enhances data transfers up to occasional transmission of large amounts of user data. Signaling procedures are specified for the provision of connection oriented services and the establishment of data channels between mobile subscribers. The time-overhead introduced with the performance of end-to-end signaling operations is a crucial performance factor that determines the provided Quality of Service (QoS). A significant time-overhead associated with the high rate establishment and release of many short-lived data channels, required during hand-over or for Internet access, would result in network performance degradation.Nevertheless, despite its main significance, there is a lack of papers in the Internet community that either investigate the issue of GPRS signaling performance or present GPRS trials and measurements. This lack becomes even more obvious and gets more importance from the moment that the deployment of GPRS, at least in the first phase, revealed significant performance delays in the connection setup times.To this respect, this paper presents the experiments conducted at a GPRS testing platform focusing on the performance assessment of signaling functionality. The trials focus on the performance evaluation of the GPRS signaling operations related to the establishment and release of user data channels through the Gn and Gi interfaces. Timing results that quantify the overall delay under diverse conditions of signaling load, rate and subscribers are presented.     

Basic Mandarin color terms

In comparative studies of basic color terms of various ethnic groups, Berlin and Kay found that the number of basic color terms used is greater, the more highly developed a culture becomes and vice-versa (Berlin and Kay 1969: 16). According to their thesis, peoples possessing the most highly developed cultures use 11 basic color terms, or the equivalents of white, black, red, yellow, green, blue, brown, orange, purple, pink, and gray. These 11 color terms are found in Japanese, Korean, and Cantonese. However, as only six are found in Mandarin, Mandarin was assigned to a lower stage of cultural development. This is incorrect. In an effort to prove this assertion, this author has conducted numerous studies. Based on research of Mandarin color terms and mapping response, this study attempts to prove that Mandarin has long contained the 11 basic color terms noted by Berlin and Kay. However, after conducting a mapping response study, it was discovered that the Berlin-Kay color set (i.e., the Berlin-Kay-MacLaury Munsell set) is inadequate for examining low saturation basic color terms such as he (Br) and cang (grayish BG), the representative colors of which are difficult to fully ascertain. During this study, this author discovered a certain degree of difficulty hindering mutual understanding between Eastern and Western cultures. Consequently, this study seeks to promote a degree of such understanding. © 1997 John Wiley & Sons, Inc. Col Res Appl, 22, 4–10, 1997.     

逻辑系统Gn中理论的真度概念及其应用

首次在命题逻辑系统中引入理论的真度概念,使得真度的概念由公式的真度推广为公式集的真度,从而简化了发散度的概念;在逻辑系统G_n中讨论了理论Γ1、Γ2和Γ1∪Γ2的真度、相容度和发散度之间的关系。     

Parametric G n blending of curves and surfaces

We introduce a simple blending method for parametric curves and surfaces that produces families of parametrically defined, G ⁿ –continuous blending curves and surfaces. The method depends essentially on the parameterizations of the curves/surfaces to be blended. Hence, the flexibility of the method relies on the existence of suitable parameter transformations of the given curves/surfaces. The feasibility of the blending method is shown by several examples. The shape of the blend curve/surface can be changed in a predictable way with the aid of two design parameters (thumb weight and balance).     

The effect of copper granules on interfacial bonding and properties of the copper-graphite composite prepared by flake powder metallurgy

The study evaluates the effect of introducing Cu granules and control milling on the microstructure, interfacial bonding and mechanical properties including sintered density, hardness, compressive strength, flexural strength and electrical conductivity of Copper-Graphite (Gr) composite synthesize by flake powder metallurgy (Flake PM). It develops the flake composite particles by control mechanical alloying (MA) which further laminates over the refine granules surface. This encapsulation facilitates the strong interfacial bonding among the composite constituents during sintering. Results highlight that the 10% Cu granules in Cu-10Gr composite exhibit excellent mechanical properties. It increases the relative density, hardness, compressive strength, and flexural strength by 4.19%, 28.23%, 98.31%, and 11.8% respectively. However, the electrical conductivity increases by 6.73% (%IACS) for 15% of Cu granules in the Cu-10Gr composite. The improvements in the results are the synergistic coordination of dispersion homogeneity, surface integrity, work hardening, and the superior interfacial adhesion between composite powder and Cu granules.     

Heavy ion beam micromachining on LiNbO3

In this work 3D micromachining of x-cut lithium niobate crystals was performed using the high energy heavy ion microbeam (HIM) at the Tandar Laboratory, Buenos Aires. The samples were machined using ³⁵Cl beams at 70 MeV bombarding energy combined with wet etching with hydrofluoric acid solutions at room temperature. As the ion beam penetrates the sample, it induces lattice damage increasing dramatically the local etching rate of the material. This technique was applied to the fabrication of 3D waveguides with long control electrodes. The resulting structures indicate that well defined contours with nearly vertical sidewalls can be made. The results also show that with fluences of only 5 × 10¹² ions/cm², this technique is suitable for the fabrication of different shapes of LiNbO₃ control-waveguides that can be used in different optical devices and matched with the existing optical fibers.     

基于Gdel蕴涵算子的导出算子的n值逻辑系统

讨论剩余类蕴涵算子之一Godel蕴涵算子的导出算子的三值系统G3和n值逻辑系统Gn（n〉3）．给出了G3的真值表，它是G2值表的扩充，也保持MP规则和正则性．讨论了G3中的重言式（tautology）与IPC（intuitionistic propositional calculus）公理之间的关系以及G3的准重言式与C2的重言式之间的关系．考虑了Gn中的子代数及不同逻辑系统Gn中重言式的比较．     

通过分配IP地址构建GPRS防火墙

GPRS通用分组无线业务是一种全新的业务,是移动通信和数据通信结合的产物。GPRS使用户能够在端到端分组传送模式下发送和接收数据,GPRS业务具有建链时间短,数据速率高,费用低等特点,同时在无线资源利用率上也有一定的提高。主要介绍GPRS中的Gn、Gi、Gp接口、IP地址的划分原则以及利用IP地址的划分设置防火墙。