基于编码模式的H.264/AVC视频信息隐藏算法

本文提出一种基于编码模式的H.264/AVC信息隐藏方法,通过调制某些宏块的编码模式,分别在Ⅰ帧、P帧和B帧中嵌入隐秘信息.对帧内4x4预测模式的宏块,是通过调整宏块中某个4×4块的编码模式嵌入隐秘信息;对P帧和B帧其它类型的宏块,则是通过调整宏块的编码模式嵌入隐秘信息,模式调整后对宏块做了优化处理.在模式调制过程中引入率失真代价,取得了较好的率失真平衡,减小了隐秘信息嵌入后对视频质量和视频码流的影响.该算法可以实现隐秘信息的快速提取,满足视频实时处理的要求,实验仿真结果证明了该算法的有效性.     

基于二项式R-D模型的多视点视频码率控制算法

针对目前尚未深入研究多视点视频编码(MVC)码率控制的状况,在分析现有视频码率控制中率失真模型的不足和多视点视频编码的特点的基础上,提出了一种基于二次率失真(R-D)模型的多视点视频编码码率控制算法。该算法的核心是先根据视差预测和运动预测的结构关系,将所有图像分成6种类型的编码帧,并改进二项式率失真模型,然后根据已编码信息进行视点间、帧层、基本单元层比特分配与码率控制。实验仿真结果表明,与目前采用固定量化参数的JVT的MVC相比,该算法能够有效地控制多视点视频编码的码率,同时保持高效的编码效率。     

回归分析建模的自适应SKIP模式预选算法

SKIP模式在最佳编码模式中占相当大的比例.SKIP模式预选可以有效减少模式选择的计算复杂度.在现有的SKIP模式预选算法中,该阈值往往不能和视频内容自适应.用回归分析建模的思路,提出了一种内容自适应的SKIP模式预选算法(CASMED),通过一个能够反映当前编码宏块特性的变量来自适应地对阈值模型进行调整.结果证明,该算法在编码性能损耗几乎为零的情况下,大大降低了模式选择算法的复杂度.     

基于Cauchy分布的H.264优化比特分配及码率控制算法

为了提高图像质量和码率控制精度,提出了一种H.264优化比特分配及码率控制算法.该算法首先基于Cauchy分布得出简化的宏块层码率模型,并引入复杂度系数MAD和头信息比特率,使码率模型可随视频内容复杂伸缩;同时采用线性模型对失真度进行预测,通过Lagrange率失真优化来选择每个宏块的量化参数,最小化整帧的失真度以实现宏块层的优化比特分配.实验结果表明,该算法能在降低比特数估计偏差、更好地跟踪目标码率的情况下,获得更好的PSNR性能.     

纹理的HEVC编码块尺寸决策算法

针对高效视频编码(HEVC)帧内编码算法计算复杂度高的问题,提出了一种基于纹理的HEVC编码块尺寸快速决策算法.首先,提出了编码块四个方向的纹理复杂度衡量指标,再通过训练视频序列选取在不同量化参数(QP)下的最佳阈值,最后根据阈值判断当前编码块的纹理复杂度,纹理复杂度高的编码块跳过率失真(RD)代价的计算,纹理复杂度低的编码块将会终止划分.实验结果表明,在全帧内模式配置下,与HM10.0相比较,该算法的编码时间可缩短45.3%,同时BD-Bitrate(Bjontegaard Delta Bitrate)增加了1.27%,BD-PSNR(Bjontegaard Delta Peak Signal-to-noise Rate)减少了0.058dB;与GEC-LEC算法相比,编码时间可节省3%,BD-Bitrate增加了0.5%,BD-PSNR减少了0.023dB.     

H.264帧内预测与帧间块模式选择快速算法

针对H.264帧间预测时的多子块模式选择和帧内预测的多模式选择问题,提出了一种实用的基于统计门限的模式快速选择算法,通过门限设定有效限定了编码模式的选择范围.多组视频序列的实验结果表明,基于统计门限的帧内预测模式选择算法在Ⅰ帧的PSNR值有微小变化的情况下,大大降低了编码时间,Ⅰ帧的编码时间降低17%～23%,PSNR下降不到0.4%.基于统计门限的帧间块模式选择算法使得平均PSNR值下降了0.047dB(PSNR最大下降不到1%),但是相对全模式预测时,编码器速度提高了20%～30%.     

一种降低外存访问带宽占有率的无损压缩算法

高清、超高清视频编解码芯片结构设计中,原始图像帧和解码图像参考帧都存在外部存储器,外存访问带宽是系统设计的一大难题.通过图像压缩编码技术来降低图像冗余度,从而减小图像的存储容量和传输带宽.针对这一问题,提出了一种改进型无损图像压缩算法.与已有无损压缩算法相比,改进后算法以宏块为预测编码的基本单元,支持宏块随机访问;首先在预测部分加入块级预测与分层预测的自适应选择;然后在编码部分融入两种预测模式的半定长变长编码.实验结果表明,可降低带宽约50%.     

结构相似度的立体视频错误隐藏

针对立体视频传输中右视点整帧丢失,提出了一种基于结构相似度(Structural Similarity,SSIM)的立体视频右视点整帧丢失错误隐藏算法。首先,提出了时域SSIM和视间SSIM的概念。然后,根据视频序列的时域相关性,将前一时刻右视点图像宏块的预测方式作为丢失图像宏块的预测方式。接着,将前一时刻右视点图像以宏块为单位进行时域和视间匹配,求取其以像素为单位的时域SSIM映射图和视间SSIM映射图。最后,计算并比较前一时刻右视点图像每个宏块的时域SSIM和视间SSIM值,得到每个宏块的预测方式,将其预测方式作为丢失帧中宏块的预测方式,从而使用运动补偿预测或者视差补偿预测的方法进行恢复。实验结果表明,与传统的算法和Pang的算法相比,PSNR值分别提高了2.76 dB和3.43 dB,且本文算法主观效果较好。     

基于自适应分段跳过规则的视点合成优化方法

对目前三维高效视频编码(3D-HEVC)标准的性能进行了分析,针对其深度图编码采用的合成视点失真变化(SVDC)计算复杂度高的问题,提出了一种基于自适应分段跳过规则的视点合成优化(VSO)方法。考虑到原始方法跳过了深度数据没有变化的模块或像素行,但忽略了可以在VSO中跳过的较小区域,该方法首先根据深度零失真准则和纹理平滑度准则判别出深度图中不会造成合成视点失真的区域,然后在深度图编码进行SVDC计算前基于自适应分段规则来提前跳过上述零失真区域,最后终止该区域的SVDC计算过程,有效地降低编码复杂度。对比实验结果证明了该方法的有效性,能在保持编码质量不变的前提下,平均减少14.2%的编码时间。     

TCM模型的自适应硬判决量化算法

在视频编码中,DCT系数分布模型是率失真理论模型的基础,视频量化一般可分别为硬判决量化(HDQ)以及软判决量化(SDQ),SDQ算法能实现最优编码性能,但其中维特比算法会导致严重的系数间串行处理依赖.比较而言,基于死区(deadzone)的HDQ算法率失真性能略有损失,但是不考虑系数间的相关性.提出了一种基于分段逼近TCM模型(Transparent Composite Model)的自适应硬判决量化算法,采用更精确的DCT分布估计模型,估算不同频率分量DCT系数的分布参数.根据模型参数及DCT系数分布参数,优化构造自适应的死区偏移量模型.实验表明,相对于固定偏移量HDQ算法,其编码性能非常接近于SDQ算法.     

Optimal supervisory control of a central chilled water plant with heuristic search sequential quadratic programming

A new methodology for adapting rigorous simulation programs to optimal supervisory control of a central chilled water plant is proposed in this article, which solves plant operation mode optimization and set points optimization by combining heuristic search with sequential quadratic programming. The mathematical basis of this algorithm is developed. A new derivative calculation strategy is introduced in set points optimization. This approach is applied to a central chilled water plant which consists of three chillers, two 3-cell cooling towers, three chilled water pumps and three condenser water pumps. Model verification study is performed. The optimal sequence of operation, set points of the decision variables at given load demand and weather condition are calculated. The plant performance and optimal control results are discussed.     

MATHEMATICAL ANALYSIS OF FACILITY-COMMODITY SCHEDULING PROBLEMS

A number of operational situations exist in which certain facilities are available and where a number of commodities must be processed on some or all of these facilities. The paper describes an algorithm to generate schedules which are near optimal or optimal with respect to the total processing time of all the commodities, the idle lime of facilities and production rate. Thus, these schedules are characterized by near minimal or minimal total processing time and idle time of facilities and near maximal or maximal production rate. Usually this algorithm does not result in the desired schedule after the first application; it is therefore proposed to generate a set “D” of schedules from which the desired schedule can be selected. A decision rule determines the optimal number of elements belonging to set D

In order to justify the concept of the algorithm for the determination of the schedules mentioned above, an analysis is given of the decision tree associated with the sequencing model in terms of the probabilities related to the nodes in the decision tree.     

Quantification of sequential failure logic for fault tree analysis

Fault tree analysis (FTA) is generally accepted as an efficient method for analyzing system failures. It is well known that a fault tree (FT) is equivalent to a minimal cut set fault tree with all minimal cut-AND structures. The minimal cut-AND structure is an AND conjunction of an output and all inputs that compose a minimal cut set. For the structure, the failed state of the output becomes true when all failed states of inputs exist simultaneously. There are cases where the output of the minimal cut-AND structure depends not only on all failed states of inputs but also on the sequence of occurrences of those failures. This sequential failure logic (SFL) is equivalently expressed with Priority-AND gates in FTA, where inputs to the gates have constant failure and repair rates. A probabilistic model for analysis of SFL was proposed and equations with multiple integration for arbitrary number of inputs were derived from the model. However, it is usually difficult to solve the multiple integration when the number of inputs exceeds a certain range. This paper presents analytical solutions of the probability that the output is in a failed state at time t and the statistically expected number of failures of the output per unit time at time t for the special case where inputs are characterized by common failure and repair rates. In addition, the analysis of FT involving SFL is demonstrated by means of software Mathematica.     

Intra mode selection in downsizing video transcoder based on H.264

An intra mode selection scheme is proposed in this work, which supports both downsizing transcoding and re‐quantization transcoding simultaneously. In the proposal, a total number of nonzero coefficients in precoded frame is used as criterion and a thresholding method is applied to select intra macroblock mode in re‐encoder. To calculate this threshold, which is related to re‐quantization parameter (denoted as Q_r), we propose a Th_I‐Q_r model which includes direct method and percentage I16MB method. In the former, an exponent model is proposed to describe relationship between the threshold and the Q_r; while in the latter, the threshold Th_I is converted into percentage of macroblocks with I16MB mode in the downsized frame (denoted as per_16), and relationship between the per_16 and the Q_r is also modeled as an exponent function. Then the two exponent models are all converted into linear regression model, and least square estimation is used to estimate the parameters of the models. Furthermore, if I4MB mode is selected for one macroblock, the intra prediction modes in precoded frame are utilized to select prediction mode for every 4 × 4 block of the macroblock in downsized frame to reduce computational complexity. We compared rate distortion performance and computational complexity of the proposed method with rate‐distortion optimization method. Simulation results demonstrate that on the precondition of compression performance of the proposal being close to the results of the rate‐distortion optimization method, the proposed method can save up to 30 and 80% in total encoding time and mode decision time, respectively. © 2009 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 19, 340–349, 2009     

基于余弦基神经网络的FIR滤波器设计

提出了一种基于余弦基神经网络FIR滤波器的设计方法。根据线性相位FIR滤波器的幅频特性是有限项的傅里叶级数,构造了一个三层余弦基神经网络模型,并给出了最优隐层神经元的个数。经模拟仿真,滤波器性能非常理想,具有同时输出低通、高通、带通、带阻各种功能,通带、阻带无过冲无波动,边界频率可以精确控制。     

Optimal temperature policies for batchwise thermally‐initiated bulk polymerization of styrene

Abstract

For batchwise thermally‐initiated bulk polymerization of styrene, the maximum principle is applied to search for an optimal temperature policy, by which the reaction time is minimal, for the system having predetermined average molecular weight and monomer conversion at end time and upper temperature limit. A set of simple equations for calculating the optimal temperature policy is obtained. Some numerical calculations are also presented.     

A summary of maintenance policies for a finite interval

It would be an important problem to consider practically some maintenance policies for a finite time span, because the working times of most units are finite in actual fields. This paper converts the usual maintenance models to finite maintenance models. It is more difficult to study theoretically optimal policies for a finite time span than those for an infinite time span. Three usual models of periodic replacement with minimal repair, block replacement and simple replacement are transformed to finite replacement models. Further, optimal periodic and sequential policies for an imperfect preventive maintenance and an inspection model for a finite time span are considered. Optimal policies for each model are analytically derived and are numerically computed.     

基于多故障假设的诊断策略研究与应用

 针对工程中最优单故障序贯测试难以隔离的多故障问题,利用Grunberg等人提出的多故障模糊组的概念,以最优单故障测试策略为基础,构造了一种多故障假设下的序贯测试算法．该算法以多故障状态集的最小碰集作为生成最优单故障策略的故障状态,生成最优单故障策略;以诊断决策树中各叶节点的多故障状态集为评判标准,确定系统的状态,完成多故障假设下的系统故障诊断;与连续使用单故障策略的方法相比,该方法提高了测试效率．以某型机载电子设备为例给出算例分析,验证了该算法隔离多故障的有效性．     

Optimal urban sewer layout design using Steiner tree problems

This article introduces a novel method using mixed-integer linear programming for optimizing sewer layouts. The research concept was obtained from the obstacle-avoiding rectilinear Steiner minimal tree technique in integrated circuit routing design. The Steiner nodes serve as optional nodes to link each sewer discharge node and flow to sinks on an optimal sewer layout. Those nodes are utilized for minimizing the total cost required for constructing pipes. All the nonlinear constraints and the objective function are transformed into a simple linear format. The optimization model analysed three types of objective function conditions—solely considering the pipe cost, solely considering the ground-cutting cost, and combining both considerations—to illustrate the importance of considering all conditions to obtain an optimal sewer layout design. The proposed optimization model can save more than 38.83% of the cost required to realize the expert’s manual sewer layout design.