移动终端视频实时传输的关键技术

随着WIFI网络的大面积覆盖,移动终端用户有了更快捷的数据传输效率以及更好的用户体验.为了解决移动终端视频实时传输过程中电量消耗过大以及因编码方式不同所造成的视频传输实时性较差的问题,分别提出适合Android系统的H.263、H.264视频流的封装策略和传输框架,利用终端对所拍摄现场进行视频采集和编码,这样能够随时将场景在服务器端实时显示.同时,为了解决终端在传输过程中电量损耗过大的问题,在对影响终端电量的不同参数分析的基础上,找出了这些参数和电量之间的权重关系,即在视频清晰度正常的情况下,影响手机电量的3个主要参数编码方式、分辨率、帧率的能耗比值约为6∶5∶1,在视频清晰度高的情况下,三者的比值约为6∶7∶2,这对移动终端的节能有很好的参考价值.     

视频流应用层组播系统设计与实现

本文设计实现了一个用于视频流分发的应用层组播系统,系统由视频采集、视频编解码、组播传输和服务器四个模块构成。视频捕获采用Video for Windows（VFW）技术实现,编解码基于H.263标准。网络结构上提出使用混合P2P树形结构,降低了中心服务器的压力。服务器负责会议成员信息的管理,为组播树的建立与维护提供支持。组播传输使用基于度约束的构造算法,考虑了节点带宽和计算能力。系统已投入运行,基本达到设计目标。     

A PREDICTION BASED ALL—ZERO BLOCK DETECTION METHOD FOR H．263

In this letter,a novel method based on Temporal and Spatial Prediction(TSP)to detect all-zero DCT coefficients based on temporal and spatial prediction between neighboring blocks is proposed.The presented algorithm uses the knowledge of all-zero block distribution in the previous frame combined with the Sum of Absolute Difference(SAD)of the corresponding macroblock as a criterion .The algorithm almost needs no additional computation ,and it shows an excellent overall detection performance in simulations.     

An investigation on microstructures and mechanical properties of explosive cladded C103 niobium alloy over C263 nimonic alloy

Futuristic aerospace applications such as advanced turbojet and scramjet engines used in subsonic, supersonic, and trans-atmospheric flights require materials with ever-increasing temperature and load bearing capabilities for improved performance. The materials C103 niobium alloy and C263 nimonic alloy are widely employed in the manufacturing of scramjet engine components. Efforts to join these two materials by fusion welding process have revealed that they are metallurgically incompatible due to the extreme propensity to form brittle intermetallics. The possibility of interdicting interlayer is explored to overcome the formulation of intermetallics and the attempts have not yielded fruitful results. Explosive welding/cladding is one of the possible ways to join these materials, as it is a solid state joining process.     

A comparative study of the vibration damping capacity of superalloys

A comparative study of nickel-base, iron-base, and iron-nickel base superalloys showed Inconel MA754 (oxide dispersion strengthened) to be particularly high in vibration damping capacity.     

Theoretical predictions and experimental validations on machining the Nimonic C-263 super alloy

The current paper presents the simulated 3D Finite Element Model (FEM) and experimental validation while turning the Nimonic C-263 super alloy using a cemented carbide cutting tool. FEM machining simulations was carried out using a Lagrangian finite element based machining model to predict the tangential cutting force, temperature distribution at tool tip and the effective stress and strain. All simulations were performed according to the cutting conditions designed, using the orthogonal array. The work piece was considered as perfectly plastic and its shape was taken as a curved model. An experimental validation of the cutting process was conducted in order to verify the simulated results of tangential cutting force and temperature at tool tip and the comparison shows that the percentage error 6% was observed and the shear friction factor 0.6 indicates good agreement between the simulated results and the experiment results. As the cutting speed is increased from 22 m/min to 54 m/min at higher feed rate, a larger strain to an extent of up to 6.55 mm/mm, a maximum value of 810 MPa stress and higher temperature localization to an extent of 620 °C at tool tip were observed.     

合成N263(SCN型)萃淋树脂用于研制高纯镍

选择利用合成的Ｎ２６３（ＳＣＮ型）萃淋树脂用于Ｃｏ＾２＋，Ｎｉ＾２＋的分离，研究了使用该树脂的料液酸度、料液浓度及洗脱液浓度等因素对钴、镍分离的影响，实验结果表明，该树脂在高纯镍制备上效果良好，料液中的镍浓度为８５％￣９５％时，一次过柱，镍的浓度可提高至９９．９５％￣１００％。本文还对萃钴机理进行了初步探讨。     

功率MOSFET管的热疲劳寿命预测

通过ANSYS有限元分析软件对TO-263器件功率MOSFET管进行电-热-机械耦合分析,并对其热疲劳寿命作出预测。首先进行了瞬态热分析,得出了芯片的热通量变化图,在此基础上进行模拟并通过Coffin-Manson定律预测功率MOSFET管的热疲劳寿命。结果表明,TO-263器件功率MOSFET管的热疲劳失效循环总数为6 113。     

一种基于DCT的频域运动估值算法

用软件实现在低码率信道上的实时视频编解码是图象压缩领域的研究热点，本文就此提出了一种基于离散余弦变换（DCT）系数的频域块匹配法，通过引入阈值矩阵，降低了运动估值的运算量，提高了搜索效率。计算机仿真表明，该算法可在PC机上用软件实时实现，具有较好的实用价值。     

基于H.263的视频监控系统的研制

基于H．263视频压缩算法，研制了一种新型视频监控系统，该系统应用DSP实现，具有结构紧凑，运行稳定，适应性强的优点，有很好的市场应用前景，