基于贝叶斯网络的无线Ad Hoc网络视频传输方法

针对AdHoc网络的视频传输,提出了一种新的网络带宽预测及控制方案．该方案基于跨层、接收端反馈以及贝叶斯网络等技术．对视频传输过程进行公式化描述,从而推导出影响视频传输质量的几个主要因素,这些因素可以通过跨层机制或接收端反馈的方式获取．根据这些影响因素,确定变量集和贝叶斯网络拓扑结构,从而构建贝叶斯网络预测模型．预测结果作为AdHoc网络带宽,根据该带宽值来控制视频编码器,动态调节输出的实时视频流码率．为验证该方案,对整个视频通信系统进行了仿真．结果显示,跟传统的传输方案相比较,夺方案能更好地利用网络带宽,减少了数据包的丢失,提高了实时视频质量．     

Equation based rate control scheme for video streaming over wireless channels with link level ARQ

INTRODUCTION Video streaming applications generally require continuous high bandwidth guarantees as well as stringent bounds on delays and jitters (Shen et al., 2004; Hassan and Krunz, 2004). Providing video streaming with acceptable quality degradation over wireless channels is fraught with challenges due to the adverse influence of bandwidth limitation, time variation, high error rate, and so on (Etoh and Yo- shimura, 2005; Shen et al., 2004; Chen and Zakhor, 2004; Hassan and Krunz, …     

Hypervideo

Methods for incorporating video in hypermedia programs are discussed in this article. Hypermedia is defined, and linear and interactive video are contrasted. It is argued that hypermedia presents unique problems in knowledge representation affecting video production, and that techniques are required differing from those for linear video and other forms of interactive video. Suggestions are made for giving interactive video the “look and feel” of hypermedia that primarily involve condensing information and accelerating presentation pace. They are based on the authors' experiences evaluating interactive media and creating “compressed” video programs. Existing media and visual ability research is re-interpreted to support these interactive, “hypervideo” methods.     

用于Internet上视频流的一种改进的基于MDC的ORB-DCT方法

One of the most interesting questions of video streaming over the Intemet is packet loss. Some error resilient technologies have been proposed to overcome quality decrease of reconsixucted video occurred due to packet loss, in which optimized reconstructionbased DCT （ORB-DCT） utilizes two-direction interleaving. An improved ORB-DCT （IORB-DCT）, which uses four-direction interleaving, is proposed in this paper. Experimental results are demonstrated to verify the effectiveness of the proposed IORB-DCT.     

An embedded packet train and adaptive FEC scheme for effective video adaptation over wireless broadband networks

INTRODUCTION With the emergence of wireless technology, various multimedia services, e.g., audio and/or video, are reaching us today through portable devices any- time, anywhere and even more increasingly accessi- ble in the near future. High quality video streaming over wireless IP is one of the most attractive applica- tions by ongoing deployment of wireless local area network (WLAN) hotspots and even powerful Wi- MAX mobile coverage. However, the present Internet is not providing a…     

Dependency-aware unequal erasure protection codes

Classical unequal erasure protection schemes split data to be protected into classes which are encoded independently. The unequal protection scheme presented in this paper is based on an erasure code which encodes all the data together according to the existing dependencies. A simple algorithm generates dynamically the generator matrix of the erasure code according to the packets streams structure, i.e., the dependencies between the packets, and the rate of the code. This proposed erasure code was applied to a packetized MPEG4 stream transmitted over a packet erasure channel and compared with other classical protection schemes in terms of PSNR and MOS. It is shown that the proposed code allows keeping a high video quality-level in a larger packet loss rate range than the other protection schemes.     

RTP-based broadcast streaming of high definition H.264/AVC video: An error robustness evaluation

In this work, we present an evaluation of the performance and error robustness of RTP-based broadcast streaming of high-quality high-definition (HD) H.264/AVC video. Using a fully controlled IP test bed (Hillestad et al., 2005), we broadcast high-definition video over RTP/UDP, and use an IP network emulator to introduce a varying amount of randomly distributed packet loss. A high-performance network interface monitoring card is used to capture the video packets into a trace file. Purpose-built software parses the trace file, analyzes the RTP stream and assembles the correctly received NAL units into an H.264/AVC Annex B byte stream file, which is subsequently decoded by JVT JM 10.1 reference software. The proposed measurement setup is a novel, practical and intuitive approach to perform error resilience testing of real-world H.264/AVC broadcast applications. Through a series of experiments, we evaluate some of the error resilience features of the H.264/AVC standard, and see how they perform at packet loss rates from 0.01% to 5%. The results confirmed that an appropriate slice partitioning scheme is essential to have a graceful degradation in received quality in the case of packet loss. While flexible macroblock ordering reduces the compression efficiency about 1 dB for our test material, reconstructed video quality is improved for loss rates above 0.25%.     

RTP-based broadcast streaming of high definition H.264/AVC video: an error robustness evaluation

In this work, we present an evaluation of the performance and error robustness of RTP-based broadcast streaming of high-quality high-definition (HD) H.264/AVC video. Using a fully controlled IP test bed (Hillestad et al., 2005), we broadcast high-definition video over RTP/UDP, and use an IP network emulator to introduce a varying amount of randomly distributed packet loss. A high-performance network interface monitoring card is used to capture the video packets into a trace file. Purpose-built software parses the trace file, analyzes the RTP stream and assembles the correctly received NAL units into an H.264/AVC Annex B byte stream file, which is subsequently decoded by JVT JM 10.1 reference software. The proposed measurement setup is a novel, practical and intuitive approach to perform error resilience testing of real-world H.264/AVC broadcast applications. Through a series of experiments, we evaluate some of the error resilience features of the H.264/AVC standard, and see how they perform at packet loss rates from 0.01 % to 5%. The results confirmed that an appropriate slice partitioning scheme is essential to have a graceful degradation in received quality in the case of packet loss. While flexible macroblock ordering reduces the compression efficiency about 1 dB for our test material, reconstructed video quality is improved for loss rates above 0.25%.     

视觉注意的数据包优先级排序策略研究

为了提高视频流传输效率,本文提出一种基于视觉注意的数据包优先级排序策略。本文排序策略主要包括三个过程：首先,根据率失真理论计算数据包客观重要性;其次,通过分析视频镜头中视觉转移特性确定视频帧的时空显著图,采用灵活宏块排序技术将显著区域与背景区域分离,并根据数据包所包含区域的时空显著度确定数据包主观重要性;最后综合数据包主客观重要性得出数据包的最终优先级。实验结果表明,本文方法能够有效提高视频流的主观重建图像质量。     

Network-adaptive HD MPEG-2 video streaming with cross-layered channel monitoring in WLAN

INTRODUCTION Video streaming service nowadays enjoys ex- plosive adoptions over all kinds of underlying net- works. To enjoy the freedom of tether-less connection over the wireless local area network (WLAN), we need to overcome many challenges of unstable wire- less channel due to fading, interference and so on. The scarce and fluctuating available bandwidth (together with time-varying delays and random/burst losses) can cause the video quality at the streaming client to be seriously deg…     

An analysis of reform in administrative system of Chinese higher education

After the founding of the People’s Republic of China, the administrative system of higher education then was characterized as “centralized”, “Tiao and Kuai” were segmented (some higher education institutions were directly administered by provincial governments, and some were affiliated to the relative administrative departments of the state) and higher education institutions (HEIs) were government-run. The reform in the administrative system of higher education launched in the 1980s broke down the segmentation of “Tiao and Kuai”, and changed it into a new administrative system emphasizing the role of the provincial governments (“Kuai-oriented mode”). Thus, HEIs gained more autonomy and tremendous changes have taken place in the relation between HEIs and the government. However, weakening the government’s administrative control over HEIs and readjusting government-HEIs relations are still the main concerns in reforming the administrative system of Chinese higher education. __________ Translated from Journal of Nanjing Normal University (Social Science), 2005 (4)     

Ready...Fire...Aim! Toward meaningful technology standards for educators and students

Conclusion I applaud ISTE, AASL, AECT, and the other organizations involved for tackling the “messy work” of developing standards for the use of technology and information resources in schools. And, at the same time, I call for a “second generation” of standards that define realistic expectations for teachers based on the subjects and levels they are called upon to teach. I propose that professional organizations from each subject work with ISTE and AECT to complete this huge task, and I propose that we consider as a “next step” the creation of a set of on-line learning experiences through which teachers can gain the identified skills and knowledge by using the very technologies we’re hoping they’ll embrace in their own teaching. There’s an old saying, “If you don’t know where you’re going, any road will do.” As far as educational technologies are concerned, this is also true. For many, the goal seems to have been simply to “get more computers into the schools,” without much thought about purpose. To return to Phil Schlechty’s metaphor, It’s generally been a brief and misguided “Ready” stage (occupied with questions like “How many do we need?” “What type?” “Where?” and “How shall we connect them?”), followed by “Fire!” (the acquisition and installation of equipment). What we need is: “Ready” (the creation of appropriate teams of people who will combine their insights to plan for the district)... “Aim” (a series of discussions about what technologies can accomplish for schools and the students they serve)... “Fire” (acquisition, installation, and professional development according to plan)... “Aim” (an assessment of how well the technologies and related programs met the intended goals, and a new planning effort designed to close the gap)... “Fire” (acquisition and implementation designed to eliminate the gap)... “Aim” (another gap assessment)... “Fire” (another attempt to close gaps)..., And so on.     

德育如何看待"利己"

One of the main reasons of the fact that Chinese moral education could hardly get out of its predicament is that “self-regard” has been simply and unilaterally interpreted as the absolute opposite to morality, where “self-regard” is merely regarded as the source of “everything evil”, and the fact that it is also the source of “everything good” is neglected. Actually, “self-regard” is the nature of human beings who go for benefit and avoid harm, which is inevitable and reasonable. It is not naturally opposite to altruism, for there is no problem concerning morality in self-regard itself, though there might be some in the means adopted. Therefore, the aim of moral education is not to deprive a person of his/her intention of self-regard, but to normalize the means he/she might adopt, so that he/she could suitably benefit himself/herself as he/she benefits others. It is proven by the past experience and the present situation that the key premise for the Chinese moral education to get out of its predicament is to set up a correct understanding over self-regard. Translated from Xueshu Yanjiu 学术研究 (Academic Research), 2005, (6): 117–120     

Knowledge of derivational suffixes in students with language learning disabilities

Knowledge of derivational suffix meanings was investigated in 10- to 12-year-old students with language learning disabilities and individually matched chronological- and language-age peers. Students produced derived forms from nonce bases in an elicitation task and selected derived forms in a forced choice task. For instance, students produced a word to label the baby of an invented animal called a TEM (TEMlet, TEMette, TEMkin, etc.) and chose an appropriate label from four options (TEMlet, TEMkin, TEMship, TEMhood). Twenty-eight suffixes (e.g., less, y, ize) conveying seven derivational meanings (e.g., “without X,” “approximately X,” “to make X”) were studied. All groups showed higher accuracy on the forced choice task than on the elicitation task. However, elicitation task accuracy of students with language learning disabilities fell substantially below that of typically achieving students. Suffixes for “agent X,” “character of X,” and “to make X” were produced in the elicitation task with higher accuracy than suffixes for “approximately X,” “diminutive X,” and “state of X.” In both tasks, suffix use was associated with productivity (i.e., regularity of suffix attachment). All groups chose highly productive suffixes (e.g., TEMlet) over less productive suffixes (e.g., TEMkin) to convey each meaning.     

Decomposition analysis of carbon reduction measures and carbon emission changes in five areas in China

Based on the analysis of primary energy consumption structure in five main provinces or municipalities in China, the factors that affect carbon emissions in the five study areas are analyzed quantitatively and comparatively with the decomposition analysis method. Empirical results demonstrate that the decomposition models of carbon emissions can be defined as “municipality model” and “provincial model”, and the population factor of “municipal model” plays a significant role in carbon emissions than that of “provincial model”. Either positive or negative effects of energy structure can be found in five different areas. However, there is a general trend that energy structure effort is becoming more and more important. Based on the characteristics and trends of carbon emissions in different areas, the carbon reduction measures are proposed as well.     

Why a Special Issue on Collaborative Learning in Postsecondary and Professional Settings?

To introduce the special issue on collaborative learning in postsecondary and professional education, the editors describe their reasons for assembling it. First, most of the existing collaborative learning research focuses on K-12 settings; second, some forms of collaborative learning are used predominantly or exclusively in postsecondary or professional education; and finally, increasing numbers of adults are getting some or all of their college education online. The introduction concludes with the editors explaining their decision not to take a position on the nomenclature question (“collaborative” vs. “cooperative” vs. “peer” vs. “small group” learning) which pervades the literature.     

Increasing student engagement by usingMorrowind to analyze choices and consequences

Conclusions Using Morrowind to bring up moral issues proved highly successful in raising the engagement level in my classes. I observedagreaternumberandvarietyofstudentsvolunteering, which cut across lines of race, class and gender. Students’ body language implied that they were actively paying attention. And the students themselves noticed greater engagement and understanding. “I think it [using a video game] was a good idea,” wrote one of my students, “Sometimes when you look at situations in a different perspective you get a better understanding.”     

Ten Essential Questions Educators Should Ask When Using Video Annotation Tools

The increasing ease and ubiquity of video has resulted in a proliferation of video annotation tools used and designed for improving education. While similar, each tool has its relative strengths and weaknesses. Choosing the “right” tool can have an impact on the experience of teachers and the effectiveness of video as a means for improving teaching and learning. In this article, we present ten guiding questions for making an informed choice about which video annotation tool will best suit each individual situation.     

Dyslexia as a limitation in the ability to process information

In an earlier paper (Miles and Wheeler 1975) it was reported that dyslexic subjects, aged over 13, were less able than suitably matched non-dyslexic subjects to respond correctly to arrays of tachistoscopically presented digits. A further experiment is now reported involving a younger age-group: 15 dyslexic subjects, average age twelve and one-half, were matched for spelling age with 15 non-dyslexic subjects, average age eight and one-half; and since the dyslexic subjects were appreciably less successful it is argued that “maturational lag” does not, on its own, fully account for the difference in performance between the two groups. A similar procedure was repeated with 41 dyslexic and 41 non-dyslexic subjects, all aged between 10.4 and 14.4, both with and without the introduction of a visual masking stimulus immediately after the test stimulus. Twenty undergraduate “fast-readers,” 20 undergraduate “slow-readers,” and four undergraduate dyslexic subjects were also compared both on their responses to tachistoscopically presented digits and on their performance in a visual search task. The results, taken in conjunction, suggest that dyslexia can be regarded as some kind of limitation in the ability to process information, perhaps affecting in particular the “visual code store” postulated by Posner et al. (1969). This paper was prepared for deliveryin absentia at the 27th Annual Conference of The Orton Society, in New York City, November 1976.     

Hutchins’s University of Utopia: Institutional Independence,Academic Freedom,and Radical Restructuring

In a crisis-plagued world looking to higher education for knowledge, wisdom, and solutions, higher education itself is stumbling. Its transformational thinking has frozen up like an overstressed computer program; and we need, in effect, to “push the reset button.” In 1953, the renowned and controversial president of the University of Chicago, Robert M. Hutchins, authored a refreshing and provocative work, The University of Utopia, containing ideas that still challenge today’s paradigms. He argued for institutional independence over “accountability,” “outcomes,” and “stakeholders.” He indicted educational evils he called “industrialization,” “specialization,” “philosophical diversity,” and “social and political conformity” and suggested ways to defeat them. Although his 56-year-old thoughts on reconceptualizing the multiversity are not a panacea, they could help higher education make a fresh start. This essay reintroduces the modern reader to Hutchins’s iconoclastic and stimulating ideas in the hope of restarting the stalled agenda for educational reform.