Influence of inner-spraying rotating tool during electrochemical milling of Nimonic-263 alloy

Electrochemical milling (EC milling) has great possibility in consequence of its flexibility and applications in the various manufacturing industries, especially in defense and biomedical industry. In future, it is likely to be one of the most capable, successful, and commercially used unconventional machining processes in the up-to-date manufacturing industries. In this research work, an attempt has been made to develop a versatile in-house EC milling setup to study the impact of inner-spraying rotating tool on the different responses of EC milling. Experiments have been performed on a special type of nickel-based (nickel–cobalt–chromium–molybdenum) superalloy commonly known as Nimonic-263 alloy specially developed for high-temperature and high-strength applications to identify the impact of major process parameters, e.g., feed rate and milling layer depth with and without tool rotation, on the responses like machining depth, side angle, surface roughness, and quality of machined profile. During EC milling of Nimonic-263 alloy, excellent surface finish ranging from 0.06 to 0.08 μm has been attained by employing mixed electrolyte, i.e., NaCl (1 M) and NaNO₃(1 M). With the incorporation of inner-spraying rotating tool, flushing can be improved to a large extent which improves the accuracy of machining.     

视频通信差错恢复技术

对当前视频压缩差错恢复和可靠视频解码（Robust video coding）算法进行了较为详细地介绍和讨论,包括：关错检测和重同步、差错纠正、差错掩盖（Concealment）以及基于反馈的差错控制。其中许多技术已被ISOMPEG－4(ver2）和ITU－TH2．63＋标准所采用。     

图像压缩技术中新型算术编码的研究与应用

在计算机科学领域和网络领域中,图像压缩技术的发展是现行的一个必然趋势,无论是有损压缩还是无损压缩,算术编码都是必不可少的一个环节.在图像压缩的技术中,算术编码占了很大的比重它提供了一种有效去除冗余度的机制,是一种目前为止编码效率最高的统计熵编码方法,他比现在最流行的霍夫曼编码的效率高10％左右,但它的编码太过复杂和一些专利方面的制约,所以没有霍夫曼编码那么广泛,我们主要研究图像信息源统计特性的基础上,分别以H.263格式和JPEG格式中的算术编码器为例,具体分析算术编码方法在动态图片和静态图片编码领域内的应用和前景.     

基于网络动态自适应的集群式监控系统

介绍了一种基于网络动态自适应的集群式监控系统的体系结构模型与实现的关键技术。系统建立在Client／Server模式基础上,采用H．263视频编码技术,利用实时传输协议RTP,实现了系统对多种网络状况的动态自适应和拥塞控制,保证了系统客户端的QoS。同时,服务端采用集群式的拓扑结构,客户端登录时采用严格的安全认证和透明接入,使得系统具有较好的安全性和可扩展性。     

A rate control scheme using Kalman filtering for H.263

This paper proposes a rate control framework for H.263 video coding called the low-delay Kalman filtering rate controller (LKFrc), whose main part is the adaptive Kalman filter. In LKFrc, a low-delay two-stage selector is proposed to select the representative frames of video. The first stage can rapidly pre-select the relatively significant frames. The second selection stage is embedded in the prediction model of Kalman filter. By the prediction model, LKFrc can distribute a proper bit budget to the pre-selected frame or definitely skip this frame. The measurement model of Kalman filter exploits a rate–distortion (R–D) model to meet the given bit budget by selecting an appropriate picture-level quantization parameter (QP). From the picture-level QP, the subsequent macroblock-level QPs are rapidly yielded by a rapid offset model using the relative macroblock activity. In comparison with the TMN8 model, the LKFrc framework can obtain better PSNRs, higher motion continuities and lower flickering effects with lower computation cost.     

实时H.263+视频编码器的DSP实现

在多媒体处理芯片TM-1300的开发平台上,快速实现了H.263 视频编码器。首先,根据H.263 编码算法要求,介绍TM-1300适合视频通信开发的特点及其开发环境;然后,将编码算法移植到TM-1300平台并进行大量的优化,其中,重点讨论了位移估值的优化算法。由实验结果可知,使用本文给出的优化算法,可以在TM-1300上快速实现H.263 编码器,满足视频实时编解码的要求,且已应用于实际视频通信产品中。     

基于脆弱水印的压缩视频错误隐藏技术

文章提出了新的基于脆弱水印的容错方案，编码端向量化系数Q-DCT系数中以数字水印形式嵌入特定信息．解码端检出水印信息以提高错误探测和错误隐藏的效果。测试表明，该方案能显著提高重建图像质量。此方案算法开销小，实用于实时环境，在无错情况下对图像质量影响小，适用于多种编码标准。     

基于多媒体DSP TM1300的运动估计算法研究及实现

提出一种用于H.263视频编码的快速运动估计的算法——NDA，通过PC仿真后将它移植到多媒体DSP TM1300上，并对它进行了改进和优化。实际运行的测试结果表明，NDA的性能要优于TMN3．0给出的运动估计算法，接近FS。文中还给出了衡量实际运动估计算法性能的测试方法。     

H．263 VIDEO CODEC IMPLEMENTATION BASED ON MULTIMEDIA DSP

This letter introduces the implementation of H.263 video codec based on multimedia DSP TM1300,and discuses several key problems related to video coding.