基于嵌入式Linux的网络电视终端的实时性开发及HTML控制方法

Linux诸多优点，和国际自由软件组织的努力，使基于Linux的开发的嵌入式产品越来越多。由于Web技术的普及，怎样在嵌入式产品上实现性能优异的Web功能成为了当前的一个研究热点。该文深入探讨在进行嵌入式应用开发过程中遇到的问题并给出了相应的解决方法。并以网络电视终端为例，详细论述具体嵌入式产品中各部分的设计和实现。重点论述基于嵌入式Linux的网络电视终端的实时性开发及HTML控制方法。

Urban functional structure characteristics and transformation in China

The paper analyzes urban functional structure characteristics of Chinese cities in 1996 using the Nelson method. The manufacturing employment percentage is much higher in metropolitan areas but is decreasing from 1989 to 1996. On the other hand, the weight of science, education, culture, hygiene, finance, insurance and real estate increases. The employment structure changes dramatically. Although the urbanization level of China is lower than that of the USA in 1955, the frequency distribution curve of urban functions is similar. The construction, transportation, commerce, finance, insurance, real estate, science, education, culture, hygiene and administration curves are normal. The mining employment converges on minor cities and the distribution is not normal. The urban function has changed with urban scale. The bigger the cities are, the smaller the manufacture, mining and construction employment weights, and the larger are the science, education, finance, insurance, real estate and administration weights. Commerce and transportation are distributed evenly and the difference is less. From the comparison in three zones of China, the employment percentage of manufacture, finance, insurance and real estate is higher in eastern coastal areas, while the employment percentage of science, education, administration is higher in western areas. (C) 2002 Elsevier Science Ltd. All rights reserved.