视频图像编码的现状与发展

本文介绍了静态和运动图像压缩编码国际标准的发展过程中出现的一系列标准,特别是JPEG2000、MPEG-4以及H.264,总结了这些国际标准的压缩效果、应用场合及相应的压缩编码算法,分析讨论了这些新标准的特点和优越性。     

南方双季稻区小行距插秧机的改进设计与试验

针对300mm行距插秧机在南方双季稻区栽插行距过大、穴数过少及不能充分发挥机插稻的增产潜力问题,在300mm行距插秧机结构的基础上,通过机械优化设计和田间农艺技术相结合的方法,对其插植部箱体、苗箱、支架(包括左右支架和中间支架)和浮板4个关键部位技术参数改进设计,研制出了适合南方双季稻区作业的2ZS-488B型(264mm行距)插秧机,并于2012-2013年在江西省2个试验点进行不同早晚稻品种机插行距的大田对比试验。结果表明:该插秧机作业性能稳定,漂秧率、伤秧率和漏插率分别为1.55%、2.68%和1.93%,相对均匀度合格率为89.54%。与300mm行距插秧机相比,其产量平均增产529.43kg/hm2,平均增产率达8.57%。该研究结果创新了南方双季稻区新的机械化栽插方式,有利于农机农艺的有效融合。     

The use of piperonyl butoxide and MGK-264 to improve the efficacy of some plant-derived molluscicides

Synergism of an oil of Azadirachta indica, a powdered extract of Allium sativum bulbs and an oleoresin of Zingiber officinale rhizomes by piperonyl butoxide and MGK-264 was studied against the snails Lymnaea acuminata and Indoplanorbis exustus. The active components of these plant-derived molluscicides, respectively azadirachtin, allicin and [6]gingerol, were also combined with these synergists. Both piperonyl butoxide and MGK-264 enhanced the toxicity of all of the test compounds. The response of snails to the synergised mixtures was both time- and dose-dependent. © 1998 Society of Chemical Industry     

FMO矩形条带对视频编码效率影响的研究

针对H.264标准的运动矢量预测方法,利用H.264标准中的灵活宏块排序(Flexible macroblock ordering,FMO)工具实现了矩形条带组的组构,并就矩形条带组对视频编码效率的影响进行了研究.结果表明,不同组构的矩形条带对视频数据的编码效率产生不同的影响.     

Amaranth as a rich dietary source of β-sitosterol and other phytosterols

The analysis of 4 commonly available amaranth varieties (Amaranthus K343, RRC1011, K433, K432) revealed the presence of all three major phytosterols (beta-sitosterol, campesterol, stigmas-terol) with a total sterol content being several fold higher than those found in other studied plants. Substantial differences in total phytosterol content and beta-sitosterol content were found between the amaranth varieties. The most commonly cultivated amaranth variety in the United States, i.e., Amaranthus K343 was found to possess the highest levels of phytosterols of the varieties tested. The possibility of screening for superior amaranth varieties with various health properties is outlined.     

基于Win CE的嵌入式无线视频传输系统的设计

文章设计能实现视频的采集、压缩、传输及远程显示,从而实现无线监控,且系统具有穗定性、可移植性,十分适合嵌入式应用领域.     

H.264中零块判决阈值的研究

在视频编码中使用基于零块判决的运动搜索算法已被公认为是一种能够加快编码速度的好方法,该算法的核心是确定一个恰当的零块判决阈值,从而使其在提高编码速度的同时不至于引起太多的图像质量下降和码率增加.在介绍H.264中的变换与量化运算的基础上,对H.264中零块判决阈值进行理论分析,得到了在H.264中可用的零块判决阈值范围,然后根据理论分析结果进行了相应的实验研究,通过对实验结果的分析,提出了在实际中可用的H.264中优化的零块判决阈值.

Abstract：

It is well-known that using motion search algorithm based on zero-block detection is a good method for accelerating video encoding. The critical technology of such methods is to select an appropriate threshold for zero-block detection so as to improve the speed of video encoding without causing too much decrease in picture quality and increase in bit-rate. Based on an introduction of transformation and quantization in H. 264, the threshold for zero-block detection is theoretically analyzed and the range of threshold for zero-block detection is given. Then some experiments about the threshold are performed according to the theoretical analysis. By analyzing the experiment results, an emulated threshold which can be used for zero-block detection in H. 264 is proposed.     

基于脆弱水印的H.264视频流完整性认证

针对H.264/AVC视频流的完整性认证问题,提出了一种基于脆弱水印的认证算法.根据公钥密钥,提取I帧的特征信息生成认证码,并以水印的形式嵌入到P,B帧的运动矢量中.在视频认证时,只需要部分解码视频流,并不需要原视频作参考.仿真实验结果表明,本算法具有较小的码率变化和视频失真,并能有效地对I,P和B帧进行完整性认证.     

一种基于线性回归模型的运动矢量重估算法

针对H.264/AVC空间分辨率缩减的视频转码,提出一种基于线性回归模型的运动矢量重估计算法.它利用原始视频流的运动矢量与下采样视频流的运动矢量之间的相关性,运用线性回归模型建模,得到下采样视频的运动矢量.仿真实验结果表明：在保持率失真性能的同时,计算复杂度明显降低.     

Effect of binary combination of some plant-derived molluscicides with MGK-264 or piperonyl butoxide on the reproduction of the snail Lymnaea acuminata

The effects of sub-lethal treatments (20 and 60% of 24-h LC(50)) with plant-derived molluscicides Annona squamosa, acetogenins, Argemone mexicana seed and protopine, in combination (1 + 5) with MGK-264 (ENT 8184) or piperonyl butoxide on the reproduction of Lymnaea acuminata has been studied. The plant-derived molluscicides and their active molluscicidal components, protopine and acetogenins, in combination with ENT 8184 or piperonyl butoxide caused a significant reduction in the fecundity, hatchability and survival of young snails. Combination of A squamosa seed powder with piperonyl butoxide was very effective as it caused a complete arrest of snail fecundity within 24 h of treatment. Removal of the snails to fresh water after the 96-h treatments caused a significant recovery in the fecundity of L acuminata.