An Improvement of MPEG-4 Rate Control Algorithm

Frame skipping in low bit video coding could significantly reduce the visual quality of reconstructed video. At the same time, if the complexity of the video sequence remains high for a long period, then driving up the long term average bit rate, the only resort of MPEG-4 Q2 rate control algorithm results in using a high quantization scale, which shows a poor visual quality of the reconstructed video. This paper analyzes the main causes of frame skipping in current MPEG-4 frame rate control scheme, and presents a new rate control algorithm based on the quadratic R-D model over a CBR channel. Key features of the present work are. 1) the bits allocated to each P-frame or B-frame are in proportion to its distance from the end of this GOP, i.e. more bits are allocated to the frames that are nearer to their reference Ⅰ -frame: 2) the target buffer level is changeable in the GOP, at the end of each GOP( five P-frames or B-frames), the target buffer level is linearly reduced from 1/2 to 1/4 of buffer size, to other frames, the target buffer level is set to 1/2 of buffer size: 3 ) a selective and judicious use of the reduced resolution mode, in addition to a modulation of the quantization scale parameter, is to control the average long term bit rate. Experimental results with different video sequences of varied complexity, encoded at low bit rates show better efficacy of the proposed algorithm than MPEG-4 Q2 rate control scheme, and the experimental results also show that the improved algorithm has significantly reduced the number of frame skipping, increased the overall PSNR, and improved the perceptual quality.     

糖尿病并发尿路感染相关因素研究

目的探讨糖尿病病人并发尿路感染的相关因素.方法调查了620例门诊或住院的糖尿病病人,并对尿路感染发病率及尿路感染与血糖、性别、年龄、病程、并发症、合并症、尿细菌学检查情况等关系作了分析.结果糖尿病病人的尿路感染发生率高,尿路感染的发生与血糖控制情况、性别、年龄、病程、并发症、合并症等有关,多种病原体可致尿路感染.结论早期严格控制血糖、防治急慢性并发症、注意会阴部清洁、积极去除炎性病变、治疗泌尿系梗阻,是防治糖尿病病人并发尿路感染的重要措施.     

矿业类院校工程力学专业“弹性力学”课程教改实践与探索

弹性力学具有复杂性、抽象性、数学知识运用较多等特点且课时较少,在这种情况下,怎样最大限度地提高"弹性力学"的教学质量?笔者结合学校矿业优势学科平台建设及多年的"弹性力学"课程教学实践经验,以特色工程教育为兴趣激发点,以论文式大作业、交互式教学、鼓励式教育和多元化成绩考核等为手段,对矿业类院校工程力学专业"弹性力学"课程的教学改革进行了探索,并在实践中取得了良好的教学效果。     

“1分36秒”引发的思考

在5．12汶川特大地震中,四川安县桑枣中学师生仅用“1分36秒”全部安全撤离,无一人伤亡,无一处房屋倒塌,创造了一个奇迹,这一切都应归功于该校校长叶志平。正是由于他的防患于未然的忧患意识,在教学楼建筑上的严要求及平时带领全校师生进行的应急演习,才能在重大自然灾害降临时创造奇迹。桑枣中学的奇迹带给我们的启示太多太多。     

当好学生健康成长的引路人

现代教育论认为：教育工作除知识对流的主线外,还有一条情感对流的主线。在几年的教育教学中,我深深地体会到“尊重、理解、信任”是学生心理健康成长的主线。     

朱自清、俞平伯诗论之比较

朱自清和俞平伯作为文学研究会的主要成员,他们都既是著名散文家、诗人,又是杰出的诗论家。但是后人对他们的研究,大多集中在了他们的散文创作上,而忽略了他们对新诗所作的贡献。本文力图通过比较他们的诗学观,试图从中找到他们和新诗运动初期的共同特质,还原他们在诗学史上应有的地位和作用。     

测电阻方法的教学设计

笔者在伏安法测量电阻这一基本方法的基础上，深入探究，引导学生归纳了另外六种方法，具体教学过程设计如下：     

词语搭配要正确

说话写句,就是把一个个词连起来,可以说是挺简单的。但是,你连接词语时随随便便的话,就会把词语搭配错,使句子意思不清楚,甚至闹出笑话来。如：“山坡上种着茂密的果园。”句中的“种着”和“果园”是不能搭配的,因为“果园”是种植果树的园地,而“园地”是不能“种”的。     

计算机网络协议测试技术分析

介绍了协议测试技术以及相关标准进展情况,着重介绍了协议一致性测试和互操作性测试,分析了二者的差异,明确了它们之间的关系.便于进一步理解协议测试技术.