Electrokinetic investigations of charged porous membranes

Asymmetric ultrafiltration membranes were prepared from fully aromatic polyamides differing in the diamine monomers of the polymeric backbone and from polysulfone. Nanofiltration membranes were made from polysulfone and polyethersulfone. The polysulfone as well as the polyethersulfone were chemically modified to change the surface charges of the membranes that were made from these polymers. This means neutral, positively as well as negatively charged membranes could be employed for the measurements. The surface properties of the membranes as a function of pH were determined by measuring the streaming potential in a perpendicular and horizontal mode. Applying proteins the values of the streaming potential changed depending on the original charges of the membranes as well as on the pH of the solution. The values shifted to either higher or lower absolute values. Thus, characterization of unused and used membranes can be carried out by electrokinetic measurements. This was also demonstrated using a membrane fitted out with invertase. The zeta potential of nanofiltration membranes, however, was only evaluated from the results obtained with the horizontally run cell.     

四路视频输入处理器SAA7144HL的应用

SAA7144HL是4个单独的多标准视频解码器的组合,是完全的3.3V CMOS电路和高集成的视频监测应用电路.详细介绍了SAA7144HL的内部功能,给出了SAA7144HL的典型应用电路.     

数字电视多频道延时直播系统的设计和实现

基于DVB标准设计直播系统,通过视频服务器方式进行延时直播,通过软件方法从多节目复用流中提取出多个单独的节目传输流,从而支持多个频道同时进行直播.可与硬盘播出系统进行系统集成.初步实现系统基本功能,按照相关标准进行传输流的技术指标检测,并对测试结果进行分析.     

采用FPGA通过BT.656接口实现传输4路视频流的方法

提出一种使用FPGA(现场可编程门阵列)实现一个ITU-R BT.656并行硬件接口传输4路CIF格式视频流的方法。该方法说明了从视频处理器到FPGA传输4路CIF格式视频流的数据结构,利用该数据结构,一个ITU-R BT.656的硬件接口可传输4路不同的CIF格式的视频数据流。FP-GA将4路视频数据流分离、插值生成D1(720×576像素)格式的数据输出给视频处理器。这种方法提高了视频处理器的扩展性,增加了视频处理器输出视频的路数。     

目标基视频编码中的运动目标提取与跟踪新算法

自动、快速的视频目标提取与跟踪是目标基视频编码中的一项关键技术.本文提出一种运动目标提取与跟踪新算法.首先,根据多帧运动信息和高阶统计检测方法得到二值运动掩模图像,然后提出一种改进分水岭算法对运动区域及其周围部分进行分割.将二者所得结果进行投影运算,得到最终运动目标.最后提出一种运动目标跟踪新算法,能对目标进行有效的跟踪.实验结果说明了本文算法的有效性.     

MPEG-2压缩域的视频数字水印新算法

视频数字水印技术是当前水印研究中的一个热点.本文提出一种视频数字水印新算法,直接对压缩后的视频数据流进行操作,根据运动矢量的特征值,将水印信息嵌入到运动矢量上,不需要完全解码和再编码过程.所提出的水印算法简单、有效,实现了水印盲检.与嵌入水印前的原视频图像相比,嵌入水印后的视频图像信噪比损失很小.     

Eliminating bandwidth estimation from adaptive video streaming in wireless networks

Dynamic Adaptive Streaming over HTTP (DASH) is the state-of-the-art technology for video streaming and has been widely deployed in both wired and wireless environments. However, mobile DASH users often suffer from video quality oscillation and even video freeze in wireless environments, which results in poor user experience. This is mainly because most quality adaptation algorithms in DASH rely highly on bandwidth estimation to adjust the video quality while wireless network bandwidth is unstable in nature and changes frequently according to wireless channel contention and condition. To provide stable performance, even during severe bandwidth fluctuation, this paper proposes the Wireless Quality Adaptation (WQUAD) algorithm, which eliminates bandwidth estimation from quality adaptation. Thanks to the Scalable Video Codec (SVC), the proposed scheme always prioritizes to lower layers over higher ones as long as the play-out buffer is not completely filled by the lower layers. As a result, the client always fills the buffer with the base layers first and then the upper enhancement layers sequentially. This horizontal adaptation is straightforward and does not require any bandwidth estimation. Through NS-2 simulations, we show that WQUAD achieves (i) stable performance, keeping the video quality level with respect to the long-term network bandwidth, (ii) effective video freeze prevention, and (iii) high video quality on average.     

地方视频会议会商系统的建设与应用

建设多媒体业务的视频会议系统,综合语音、图像、数据等信息,通过网络介质进行远距离高速传输,可增强在不同区域交流的亲切感和临场感,提供一种简便而有效的工作手段,充分发挥视频会议实时高效的特点,将显著提高决策和工作效率,尤其能为政府在防灾减灾的指挥决策方面起到积极快速反应的作用。     

Cross-layer optimized authentication and error control for wireless 3D medical video streaming over LTE

3D video for tele-medicine applications is gradually gaining momentum since the 3D technology can provide precise location information. However, the weak link for 3D video streaming is the necessary wireless link of the communication system. Neglecting the wireless impairments can severely degrade the performance of 3D video streaming that communicates complex critical medical data. In this paper, we propose systematic methodology for ensuring high performance of the 3D medical video streaming system. First, we present a recursive end-to-end distortion estimation approach for MVC (multiview video coding)-based 3D video streaming over error-prone networks by considering the 3D inter-view prediction. Then, based on the previous model, we develop a cross-layer optimization scheme that considers the LTE wireless physical layer (PHY). In this optimization, the authentication requirements of 3D medical video are also taken into account. The proposed cross-layer optimization approach jointly controls and manages the authentication, video coding quantization of 3D video, and the modulation and channel coding scheme (MCS) of the LTE wireless PHY to minimize the end-to-end video distortion. Experimental results show that the proposed approach can provide superior 3D medical video streaming performance in terms of peak signal-to-noise ratio (PSNR) when compared to state-of-the-art approaches that include joint source-channel optimized streaming with multi-path hash-chaining based-authentication, and also conventional video streaming with single path hash-chaining-based authentication.