基于SOC的PAGER控制芯片设计

文章讨论了PAGER控制器芯片（ZQD021）的系统设计，该控制器内部集成了FLASH，SRAM，POCSAG协议解码器和嵌入式MCU CORE。重点分析了芯片的可测性设计（DFT），内嵌FLASH设计，低功耗设计，其设计方法和思路对消费类和嵌入式控制芯片的设计有一定的借鉴意义。     

Decay of the remanent magnetization in the asymmetric spin chain

The dynamics of the one-dimensional spin glass with asymmetric interactions between neighboring spins is considered. We confine ourselves to discrete couplings with values ±J. We show that the algebraic decay of the remanent magnetization of the infinite ±J-spin chain at zero temperature is only valid for symmetric couplings. Our analytical investigations as well as computer simulations show stretched exponential decay for any finite concentration of antisymmetric bonds. Thus, the asymmetric ±J-spin chain shows an asymmetry-induced phase transition at zero temperature.     

Image segmentation towards new image representation methods

Very low bit-rate video coding has recently become one of the most important areas of image communication and a large variety of applications have already been identified. Since conventional approaches are reaching a saturation point, in terms of coding efficiency, a new generation of video coding techniques, aiming at a deeper “understanding” of the image, is being studied. In this context, image analysis, particularly the identification of objects or regions in images (segmentation), is a very important step. This paper describes a segmentation algorithm based on split and merge. Images are first simplified using mathematical morphology operators, which eliminate perceptually less relevant details. The simplified image is then split according to a quad tree structure and the resulting regions are finally merged in three steps: merge, elimination of small regions and control of the number of regions.     

Low complexity inter coding scheme for Versatile Video Coding (VVC)

The latest coding standard Versatile Video Coding (VVC) developed by the Joint Video Experts Team (JVET) and Video Coding Experts Group (VCEG) was finalized in 2020. By introducing several new coding techniques, VVC improves the compression efficiency by 50% compared with H.265/HEVC. However, the coding complexity increases dramatically, which obstructs it from real-time application. To tackle this issue, a fast inter coding algorithm utilizing coding information is proposed to speed up the coding process. First, by analyzing the coding areas of the neighboring CUs, we predict the coding area of the current CU to terminate unnecessary splitting modes. Then, the temporally optimal coding mode generated during the prediction process is further utilized to shrink the candidate modes to speed up the coding process. Finally, the distribution of neighboring prediction modes are exploited to measure the motion complexity of the current CU, based on which the unnecessary prediction modes can be skipped earlier. Experimental results demonstrate that the proposed method can reduce the coding complexity by 40.08% on average with 0.07 dB BDPSNR decrease and 1.56% BDBR increase, which outperforms the state-of-the-art approach.     

Visual video evaluation association modeling based on chaotic pseudo-random multi-layer compressed sensing for visual privacy-protected keyframe extraction

In current society, artificial intelligence processing technology offers convenient video monitoring, but also raises the risk of privacy leakage. Theoretically, the data used in intelligent video processing methods may directly convey visual information containing private content. For the above problem, this paper uses a multi-layer visual privacy-protected (VPP) coding method to blur private content in the video at the visual level, while avoiding the loss of important visual features contained in the video as much as possible. And this provides a guarantee of the quality of the subsequent keyframe extraction step. Then a visual evaluation algorithm is proposed for assessing the quality of VPP-encoded video privacy protection. And the experiment shows that the results are consistent with those of subjective evaluation. In addition, for VPP-encoded video, we propose an unsupervised two-layer clustering keyframe extraction method with corresponding performance evaluation index. Finally, an association model is established to balance the privacy protection quality and the keyframe extraction performance.     

无速率编码中度分布的研究和发展

无速率编码作为一种纠删码,在减少反馈重传的同时也具有码率灵活、编译码简单的特性,在许多领域都有广阔的应用前景。度分布作为无速率编码设计的基础,对无速率编码的性能有至关重要的影响。随着无速率编码的广泛应用,度分布的设计也需要随着场景和需求的变化进行优化。首先论述了无速率编码的发展与应用,从几种经典的无速率编码和度分布开始,详细地从应用场景、优化目标以及现有优化方法 3 个角度,对目前无速率编码中度分布的研究和发展进行了总结与分析。最后,对无速率编码和度分布的发展应用趋势进行了分析与展望。     

Extracting embedded messages using adaptive steganography based on optimal syndrome-trellis decoding paths

Privacy protection is the key to maintaining the Internet of Things (IoT) communication strategy. Steganography is an important way to achieve covert communication that protects user data privacy. Steganalysis technology is the key to checking steganography security, and its ultimate goal is to extract embedded messages. Existing methods cannot extract under known cover images. To this end, this paper proposes a method of extracting embedded messages under known cover images. First, the syndrome-trellis encoding process is analyzed. Second, a decoding path in the syndrome trellis is obtained by using the stego sequence and a certain parity-check matrix, while the embedding process is simulated using the cover sequence and parity-check matrix. Since the decoding path obtained by the stego sequence and the correct parity-check matrix is optimal and has the least distortion, comparing the path consistency can quickly filter the coding parameters to determine the correct matrices, and embedded messages can be extracted correctly. The proposed method does not need to embed all possible messages for the second time, improving coding parameter recognition significantly. The experimental results show that the proposed method can identify syndrome-trellis coding parameters in stego images embedded by adaptive steganography quickly to realize embedded message extraction.     

一种基于Arnold置乱和DCT编码的无载体信息隐藏方法北大核心CSCD

近年来十分火热的搜索映射式无载体信息隐藏虽具有一定的鲁棒性,但其隐藏容量较低、传输负载大且算法复杂度高。针对以上问题,该文章提出一种基于Arnold置乱和离散余弦变换(discrete cosine transform,DCT)编码的无载体信息隐藏方法。该算法先对图片进行Arnold置乱,再对DCT后的低频系数进行编码,接着更换置乱参数来构建索引表。选择索引表中与秘密信息相同的编码值所对应的参数构建候选队列,最后筛选出鲁棒性强的参数作为密钥发送给接收方。实验结果表明,该方法与现有方法相比大大提高了嵌入容量,拥有更强的抗JPEG压缩性能。并且减少了传输负载,算法简捷,具有较强的应用价值。     

Evolution of the structural stability of large Cu,Ni, Pd,and Ag clusters with size: An analysis within the embedded atom method

A study of the structural stability of clusters made up of a single component has been carried out within the Embedded Atom Method. Perfect icosahedral and cuboctahedral Cu, Ni, Pd, and Ag clusters with up to 5083 atoms have been compared. The icosahedron is found to be the stable structure for small clusters, and a change of structure from icosahedral to cuboctahedral is found as the cluster size increases. A contraction of the interatomic distances results when the cluster size decreases.