Growing process of CdS nanoclusters in zeolite Y studied by positron annihilation

Zeolite Y has been used as the host to generate CdS nanoclusters. The location of CdS nanoclusters inside zeolite hosts was confirmed by the blue-shifted reflection absorption spectra with respect to that of bulk CdS materials. But which kind of cage inside zeolite Y, sodalite cage or supercage, was preferred for the CdS clusters remained unclear. In this paper, we conducted positron annihilation spectroscopy (PAS) measurements for the first time on a series of CdS/Y zeolite samples and concluded that CdS clusters were not located in supercages but in smaller sodalite cages. The stability of CdS clusters inside the sodalite units was due to the coordination of Cd atoms with the framework oxygen atoms of the double six-ring windows. Moreover, PAS revealed some important information of surface states existing on the interfacial layers between CdS clusters and zeolite Y. (C) 2001 Elsevier Science B,V, All rights reserved.

基于虚拟机架构的操作系统监控技术研究

当今随着计算系统资源和规模不断扩展，计算系统的虚拟化作为一种新型的计算模式，成为了研究热点。相对于传统的计算机架构，虚拟化计算系统在很多方面具有优势。在基于虚拟机架构的监控模型中，位于虚拟机监控器(Virtual Machine Monitor, VMM)中的监测模块获得比客户机内核更高的权限，并且对于客户机而言完全透明。所以相对与在传统操作系统环境中的监控模型，基于虚拟化架构可以对客户机操作系统进行更深入的监测。 Xen 是一个开放源代码的 VMM，由剑桥大学开发。由于其开源性质，非常适合在其基础上进行虚拟化的研究和开发。本文调研了Xen 的体系架构，以及 Xen 对 Intel 的 VT硬件虚拟化技术的支持。并研究了 Xen 的几种对客户机的内存管理方式，着重介绍了使用影子页表管理全虚拟化客户机内存的方法。 本文主要贡献是通过对上述知识的学习和分析，设计了基于Xen 虚拟机架构，对全虚拟化客户机操作系统的监控框架。并在这一框架基础上，利用对x86虚拟内存管理的页表属性控制，实现了对客户机 Windows 中指定进程的几种行为的监控实例 CASMonitor。包括通过影响 SYSENTER 指令的执行，监控Windows 中的系统调用；通过捕获虚拟机中进程对指定范围内存的写和执行操作，提供了一种可以监测程序自修改代码的技术，并能获取相关信息以对其进行后续分析处理。相对于现有的自修改代码监测技术，CASMonitor利用虚拟机架构可以实现动态，透明并且自动地监测。 关键词：虚拟化，Xen，自修改代码，监控

应用软件发布与恢复机制研究

在传统的软件开发过程中，开发者更关注软件开发生命周期的管理，而对软 件开发后生命周期的管理并不热心。随着信息技术和互联网技术的快速发展，软 件产业发生了重大变革。新的软件运营模式要求对软件开发后生命周期管理提供 完善的支持。 本文首先回顾了传统的软件发布技术。PXE技术提供了网络远程引导功能， 该技术结合网络远程唤醒技术Wake-on-LAN使得通过网络远程控制客户机安装 操作系统成为可能。网络安装软件有基于网络克隆的Symantec Ghost和Windows Server 2003 RIS；有基于脚本的Kickstart；有基于镜像的SystemImager suite。在 开源系统中，APT是最为著名的包管理工具，它较为完善地解决了软件包之间的 依赖关系。网络更新技术则提供了更多的功能，目前的更新软件有：通用产品更 新器Install Shield, Power Update, Software Dock, Marimba等；以及供应商产品更 新器Microsoft Update, Windows Update, Microsoft SUS, Microsoft SMS, Norton AntiVirus LiveUpate等。 美国Colorado大学为软件开发后生命周期建立了一个体系结构Software Dock，并实现了一个粗略的原型系统。本研究侧重分析了应用软件的发布和恢 复机制，提出以用户的角度看待软件开发后生命周期管理的思想，建立了一个软 件发布机制体系结构，试图解决如下问题：系统重装后的运行态恢复，即系统崩 溃后如何快速而灵活地恢复到指定状态点并且重建该状态点的运行状态(即运行 态恢复)；应用软件恢复透明化和即点即用。

藏文基本字符集的支持在OpenOffice.org中的实现方法

以开源项目OpenOffice.org为基础,针对藏文基本字符集在OpenOffice.org办公套件本地化的过程中出现的技术难点,根据藏文自身的特点结合OpenOffice.org中文本显示模块Icu的结构,解决了藏文小字符集在OpenOffice.org办公套件中显示、排序和转写等和文化与文字紧密相关的问题。该本地化软件可以跨Windows和Linux平台运行。

蒙古文显示在OpenOffice.org办公套件中的实现

蒙古文是一种复杂文字,目前操作系统和办公套件都还不支持蒙古文的显示.OpenOffice.org是可以运行在Linux和Windows上跨平台的办公套件,它分别使用ICU LayoutEngine和Uniscribe进行复杂文字处理.本文以支持蒙古文处理的Linux版本OpenOiffice.org为基础,详细分析了OpenOffice.org在Linux和Windows系统上的复杂文本处理过程,采用Uniscribe与ICU相结合的方案,实现了OpenOffice.org在Windows平台上对蒙古文的显示.

Polarization properties of elliptical core non-hexagonal symmetry polymer photonic crystal fibre

In this paper, polarization properties and propagation characteristics of polymer photonic crystal fibres with elliptical core and non-hexagonal symmetry structure are investigated by using the full vectorial plane wave method. The results how that the birefringence of the fibreis induced by asymmetries of both the cladding and the core. Moreover, by adjusting the non-symmetrical ratio factor of cladding eta from 0.4 to 1 in step 0.1, we find the optimized design parameters f the fibre with high birefringence and limited polarization mode dispersion, operating in a single mode regime at an appropriate wavelength range. The range of wavelength approaches the visible and near-infrared which is consistent with the communication windows of polymer optical fibres.

称重式蒸渗仪系统改进及在农田蒸散研究中的应用

水分是制约黄土丘陵区农作物正常生长和农业生产的关键因子。该区年平均降水量少且季节多变,研究农田土壤水分平衡对该区旱地农业生产具有重要意义。土壤蒸渗仪(Lysimeter)可测量总蒸散量、渗漏量等有关水量平衡的各个分量,具有其它装置和方法不可比拟的优越性。它为田间蒸散和降水入渗实验研究提供了一种较先进的量测方法和技术手段。它对推动我国实验水文学的发展具有重要作用,并为相关领域的科学研究提供了一种较先进的技术设备和实验环境。中国科学院安塞试验站对原建造的用于测定农田蒸腾蒸发转化的称重式蒸渗仪在2005年对称重感应系统、电源进行改造,主要对主机、采集软件进行了重新更新,使其可直接在Windows界面下工作,数据采集更加方便,将测量出来的模拟量信号转换为数字信号,经处理显示并记录在数据采集器内。改进后蒸渗仪主要有以下特点:(1)土柱重19~26t,蒸渗仪精度为152 g(0.05 mm),可测量蒸腾蒸发量和地下水对土壤水的补给量与入渗量;(2)蒸渗仪面积3 m2(1.5 m×2 m),深度3 m,可充分允许农作物根系发育与吸水,土壤水和地下水转化,地下水位变化等过程进行,蒸渗仪的供排水系统能够在蒸渗仪内模拟实际地下水...

基于AJAX和Server Push的Web树组件设计与实现

树组件[1]的功能简单、界面表现力较差,而且组件效率较低,难以满足复杂的应用需求.基于目前流行的AJAX技术,给出一个具有较强的可扩展性的Web树组件的设计和实现.组件在Web上为用户提供了类似于在Windows资源管理器中对目录树操作的基本功能和用户体验.另外,还采用ServerPush技术对树组件进行了改进,解决了AJAX应用中可能出现的数据不一致的问题.

Study on the forecast effects of PI method to the north and southwest China

In this paper, the codes of Pattern Informatics (PI) method put forward by Rundle et al. have been worked out according to their algorithm published, and the retrospective forecast of PI method to North China (28.0 degrees-42.0 degrees N, 108.0 degrees-125.0 degrees E) and to Southwest China (22.0 degrees-28.3 degrees N, 98.0 degrees-106.0 degrees E) has been tested. The results show that the hit rates in different regions show a great difference. In Southwest China, 32 earthquakes with M(L)5.0 or larger have occurred during the predicted time period 2000-2007, and 26 out of the 32 earthquakes occurred in or near the hot spots. In North China, the total number of M(L)5.0 or larger was 12 during the predicted time period 2000-2007, and only 3 out of the 12 earthquakes occurred in or near the hot spots. From our results, we hold that if the PI method could be applied to all kinds of regions, the parameters associated with time points and time windows should be chosen carefully to obtain the higher hit rate. We also found that the aftershocks in a strong earthquake sequence affect the PI results obviously. Copyright (c) 2009 John Wiley & Sons, Ltd.

Study on the forecast effects of PI method to the north and southwest China

In this paper, the codes of Pattern Informatics (PI) method put forward by Rundle et al. have been worked out according to their algorithm published, and the retrospective forecast of PI method to North China (28.0 degrees-42.0 degrees N, 108.0 degrees-125.0 degrees E) and to Southwest China (22.0 degrees-28.3 degrees N, 98.0 degrees-106.0 degrees E) has been tested. The results show that the hit rates in different regions show a great difference. In Southwest China, 32 earthquakes with M(L)5.0 or larger have occurred during the predicted time period 2000-2007, and 26 out of the 32 earthquakes occurred in or near the hot spots. In North China, the total number of M(L)5.0 or larger was 12 during the predicted time period 2000-2007, and only 3 out of the 12 earthquakes occurred in or near the hot spots. From our results, we hold that if the PI method could be applied to all kinds of regions, the parameters associated with time points and time windows should be chosen carefully to obtain the higher hit rate. We also found that the aftershocks in a strong earthquake sequence affect the PI results obviously. Copyright (c) 2009 John Wiley & Sons, Ltd.

不同长度β_2整合素_M亚基与ICAM-1的亲和性比较

<正>整合素作为细胞表面糖蛋白受体,介导细胞-细胞、细胞-胞外基质以及细胞-病原体间粘附和信息传递,在免疫应答、凝血反应、炎症反应、肿瘤转移和创伤愈合等许多病理生理过程中起重要作用。整合素是由α、β两个亚基非共价结合而成的异源二聚体,其结构类似于两条近平行的腿部支撑着一个球形的头部。研究表明,β_2整合素_M亚基头部的.domain为与配体直接作用的结构域,并可通过"open"或"close"的构象变化

多路谱仪放大器输出信号的读出与数据采集

A read-out and data acquisition system for the outputs of multi-channel spectroscopy amplifiers is introduced briefly in this paper.The 16-channel gating integrator/multiplexer developed by us and PXI-DAQ card are used to construct this system.A virtual instrument system for displaying,indicating,measuring and recording of output waveform is accomplished by integrating the PC,hardware,software together flexibly based on the Lab Windows/CVI platform in our read-out and data acquisition system.In this system,...中文文摘：简要介绍一个针对多路谱仪放大器的读出与数据采集方法与系统。该系统基于16通道门积分/选通输出电路和通用PXI-DAQ卡构建。利用Lab Windows/CVI平台构建虚拟仪器,灵活地将计算机、硬件、软件结合起来,设计了一个读出与数据采集系统。在该系统中,一个ADC通道可以面对16个谱仪放大器的输出,有效地提高了系统的集成度,降低了数据采集系统的成本。该设计为利用通用型谱仪放大器构建数百参数的信号读出与数据采集系统提供了一种新的方法。通过实验验证,证明该系统具有智能化、可靠性高、实时性强、成本低等优点。

基于加速器控制系统的输入法开发设计

加速器控制系统部分机箱位于加速器主环内部,由于空间的原因,只能使用小键盘,本文作者开发设计了用于此系统的输入法,通过对输入法的开发设计,本质地认识了Windows平台下输入法的开发原理和基本方法。本文对Windows平台下输入法开发设计的两大过程:输入法的开发和安装程序设计进行了深入的分析,并总结了Windows平台下输入法的开发原理。