一类二维迭代系统的周期性

本文主要考虑了一类二维平面上的间断动力系统的周期性。由于迭代函数的不连续性,这给我们考虑其动力学性质带来了极大的不便。所幸的是我们采用符号动力系统的相关理论,能简化我们的运算与讨论,得到的主要结果是该系统的周期点个数的表示。     

论学生在综合工程教育及具体学科学习过程中的适应性问题

现实中学生在综合工程教育及具体学科学习的适应性问题往往被忽视.众所周知,知识结构体系无论是从基本到复合,从初级到高级,都没有空白和跳跃,也没有重要与不重要、需要与不需要、有用与无用之区别,这就需要对教育体制系统进行重新审视.这种对于多层次的教育系统中各种关联的考察可被视为在专家预备教育的科学体系组织轨迹中的第一步尝试.     

一种基于XML的图像高效存储方法

XM L技术广泛应用于数据库和在网络传输。但是XM L主要适用于文本数据,所以对于图形数据一般是分开传输的,从而改变了传输的统一性。本文提出了一种简单高效的图像转换的方法,从而实现了图像在XM L中的传输。     

电影媒介的影像编码和意义播撒

本文通过对电影文本《云水谣》影像符码的局部解读,分析电影媒介在社会传播中独特而深刻的意义播撒.     

一种新型的自动切换量程峰值检测系统的设计

针对常用的峰值检测系统是进行手动机械切换量程或不能切换量程的缺陷,对新型的能自动切换量程的峰值检测系统进行了探讨.     

The role of visual and phonological representations in the processing of written words by readers with diagnosed dyslexia: evidence from a working memory task

The aim of the study was to elucidate the nature and efficiency of the strategies that readers with phonological dyslexia use for temporary retention of written words in Working Memory (WM). Data was gathered through a paradigm whereby participants had to identify serially presented written (target) words from within larger word pools according to their presentation order, with word pools containing code-specific distracter (CSD) words and non-code-specific distracter (NCSD) words. Analyses focused on three aspects of performance: (1) false recognition of target words; (2) correct recognition of target words; and (3) retention of word presentation order. Participants were readers with diagnosed phonological dyslexia (n = 20, mean grade level = 9.05 [0.89]) and a control group of regular readers (n = 25, mean grade level = 9.00 [0.76]). Results provide direct evidence that the dyslexic readers and the regular readers used essentially different memory coding strategies for the temporary retention of written words, with the former predominantly relying on a visual strategy and the latter on a phonological strategy. Findings further pinpointed a notably impoverished ability of the dyslexic readers to retain word presentation order. The implication of these findings is discussed in relation to theories predicting the acquisition and mastery of reading.

可伸缩编码中的RTP封装及其应用

可伸缩视频编码（Scalable Video Coding,SVC）一般采用实时传输协议（Real-time TransportProtocol,RTP）保证视频数据流的实时传输和质量监测。本文在分析SVC码流结构和RTP协议的基础上实现了H.264/SVC视频数据的RTP封装算法,提出了一种基本层与增强层分离的灵活封装机制模拟SVC在不同差错信道中的传输,通过在H.264/SVC模拟测试环境中的实验证明RTP封装机制的有效性,标准兼容性和可扩展性。     

浅析植入式广告的生存状况

文章讨论植入式广告的生存状况,整体分两部分即植入式广告的生存的土壤与其发展面临的问题。揭示广告采用新形式在特定的传播环境中自身的适应与调节能力,及其与营销策略的契合与对受众注意力产生的影响。     

Optimum weighting-coefficient-pair in inter-carrier interference self-cancellation scheme of OFDM system

As one of the most important components of the wideband wireless access technique, orthogonal frequency division multiplexing （OFDM） has a high usage rate of spectrum and combats inter-symbol interference （ISI） in multi-path fading channel. However, when there are frequency offsets during the signal transmission, the inter-carrier interference （ICI） is introduced, which significantly degrades the performance. The existing ICI self-cancellation schemes such as PCC-OFDM are not optimum to minimize the interference considering both noise and ICI. In this paper, a new metric named S1NR （signal-to-interference- and-noise ratio） is proposed. We discuss the optimization issue when a constant frequency offset exists and in time-varying channels. The optimum weighting-coefficient-pair （OWCP） is obtained, which maximizes SINR theoretically through the alternant iteration algorithm. Simulations show that the performance of OWCP-OFDM is better than that of PCC-OFDM, especially when the frequency offset is large. Although the ICI self-cancellation scheme suffers bandwidth inefficiency, from the simulation results we can also see that the performance of OWCP-OFDM is much better than that of the standard OFDM systems with the same bandwidth efficiency when a frequency offset exists. Moreover, since the redundant modulation provides the capability to suppress ICI as well as a receiving SNR gain, it can be considered as exchanging the bandwidth for SNR.