在ICU中实现少数民族文字的处理

基于ISO/ IEC 10646和UNICODE国际标准,用传统的字体技术(如TrueType)来实现少数民族文字处理所面临的一个"瓶颈"问题是:"变形显现字符"不存在确定的码位.这也是多年来民文系统重复开发、互不兼容的根本原因.本文基于ICU的文字处理体系结构,阐述了完全支持Unicode标准的少数民族文字(本文主要指蒙古文字、维文、藏文等)的实现方法.文中首先介绍了少数民族文字的特点,分析其与拉丁文字、汉字在计算机输入、输出过程中的不同之处,并指出少数民族文字处理的难点.其次介绍了一种能满足少数民族文字处理需求的字体技术--OpenType.最后,阐述了文字处理引擎的工作原理,以及ICU中如何实现对少数民族文字的支持.

基于ICU的复杂文本布局引擎设计与跨平台应用研究

ICU复杂文本布局引擎与其他应用较为广泛的复杂文本布局引擎相比的一大长处是它的开放源代码.通过分析ICU源码,并以此为基础设计新的复杂文本的布局引擎.首先简要介绍了复杂文本布局引擎的一般原理,然后以复杂文字语言蒙古文为例,详细探讨了基于ICU的复杂文本布局引擎的设计思路和方法,最后对复杂文本布局引擎的跨平台应用进行了深入研究.

传统蒙古文变形显示机制研究与实现

多年来蒙古文处理系统重复开发、互不兼容的根本原因就是没有统一的标准:编码标准不统一、字库标准不统一、输入法不统一。随着国际化、多语言化的发展,开发基于ISO/IEC10646和UNICODE国际编码标准、OpenType智能字体技术的不同语言文字处理系统已经成为趋势。本文阐述了一个蒙古文显示系统,它完全支持Unicode标准并使用了OpenType技术自动进行字形选型,其实现是基于QT库的,但核心实现很容易移植到Pango,ICU等其他复杂文本布局(CTL)处理项目中。

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.

地下水位上升造成的黄土远程滑坡形成机理与数值模拟研究

Based on field survey, laboratory testing and numerical modeling, engineering characteristics of undisturbed loess and the mechanism of long-runout loess landslides caused by underground water level rise, as well as the formation conditions and spatial distribution of landslides, are systematically studied and analyzed. Loess landslides at south Plateau of Jingyang County are mainly classified as flowslide, slide and fall. Flowslide is the main type characteristic of high velocity, long runout and multi-stages. The steep relief composed of loose structured loess-old aged soil serials and the rise of groundwater table are the predominant conditions for landslides in the study area. To study loess mechanic poperties and loess landslides mechanisims, isotropically and anisotropically consolidated undrained compression(ICU and ACU) tests and constant-deviator-drained compression (CQD) tests were carried out on undisturbed samples. The results of undrained compression tests performed at the in-situ stress level show that the soils are of consistently strain-softening in the stress-strain relations and cause high excess pore pressure. The steady-state line and the potential region of instability are obtained from ICU and ACU test results. A necessary condition for liquefaction is that the soil state initially lies in or is brought into the potential instability region. In addition, a strong strain-softening model is also formed. CQD tests demonstrate that the mobilized friction angle is far less than the steady-state angle and that the soil experiences undrained contractive failure suddenly at very small strains when its stress path during drained loading tries to cross the potential instability region，thus validates the proposed instability region. Based on the location of the region of potential instability and the stress state of slope soil, a method of static liquefaction analysis is proposed for loess landslides caused by rise in groundwater table. Compared with other liquefaction analysis methods, this method overcomes the limitations inherent in conventional slope stability method and undrained brittleness index method. Triaxial tests composed of constant water content (CW) and wetting tests at constant deviator stress are performed on undisturbed unsaturated samples. The stress-strain relation of CW tests takes on strain-hardening behavior; The results of wetting tests at constant deviator stress designed to study the mechanics of failure of unsaturated loess caused by an increase in the degree of saturation (wetting) shows that a contractive failure occurs in the undisturbed samples. On the basis of the above triaxial test results, the initiation of static liquefaction is presented for long-runout loess landslides caused by rise in groundwater table, that is, the loess slope soil gradually transfer from unsaturated to saturated state under the infiltration of irrigation. A contractive failure occurs in the local region at very small strain by increasing the pore-water pressure at constant deviator stresses under drained conditons. It is the contractive failrue resulting from rise of pore pressure that leads to high excess pore pressure in the neighbour soil which reduces shear resistance of soil. The neighbour soils also fail due to the rapid increase in pore-water pressure. Thus a connected failure surface is developed quickly and a flowslide occurs. Based on the saturated-unsaturated seepage theory, transient seepage is computed using the finite element method on loess slope under groundwater table rise. Pore-water pressure distribution for every time step after irrigation are obtained. The phreatic surface in the slope increases with the groundwater table. Pore-water pressure distribution within 8m above the phreatic surface changes very quickly，but the water content and pore water pressure in the region ranging from 8m above the phreatic surface up to ground surface is almost not affected and the matric suction usually is kept at 100～120 kPa. Based on the results of laboratory tests and seepage flow analysis, the development process of loess landslide is modeled considering groundwater table rise. The shearing plastic zone first occurs at the slope toe where the soil is soaked for long term during rise in groundwater table. As irrigation continues, the shearing plastic zone gradually extends to the interior soils, with the results that the tensile plastic zone occurs at the slope crown. As time goes on, both the shearing plastic zone and tensile plastic zone continue to extend. Then a connected plastic zone is formed and fowslide occurs. In comparision to laboratory test results, the results of numerical simulation quite well verify the presented mechanism of static liquefaction of long-runout loess landslides caused by rise in groundwater table.