Subjects: Digital Publishing >> New Media submitted time 2023-10-08 Cooperative journals: 《中国传媒科技》
Abstract：发射技术包括有线和无线两种模式,两者相比,无线发射技术更有优势。无线发射的成本较低、操作性较强,是在有线发射的基础上进行优化的结果。这些创新使得无线发射技术难以受到技术层面的局限。如今,我国的大部分地区已经开始运用广播无线发射技术,甚至一些偏远的农村,也依然受到无线发射技术的惠及。随着近年来农村无线发射技术的改革和发展,越来越多的地区的人们都可以享受到清晰的电视节目和广播信息。本文主要针对无线电视发射的运行现状进行分析,并对未来该技术的发展进行预估,希望借本文可以为无线发射技术研发人员提供有效的参考。
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2022-05-10 Cooperative journals: 《计算机应用研究》
Abstract： Action recognition(AR) is a hot research area in computer vision field, and has an extensive application prospect for security monitoring, autopilot, production safety etc. Firstly, this paper analysed the connotation and denotation of AR and put forward the technical challenges; Secondly, the paper analysed and compared the working principles of AR from three aspects: time feature extraction, efficient optimization and long-term feature capture; Thirdly, in order to select suitable AR models for different application scenarios, this paper compared the performance characterization of 43 benchmark AR methods in recent ten years based on UCF101, HMDB51, Something-Something and Kinetics400 data sets. Finally, this paper pointed out the future development direction of AR field, and the research results can provide theoretical reference and technical support for video feature extraction and visual content understanding.
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-09-12 Cooperative journals: 《计算机应用研究》
Abstract： Motion features are difficult to extract which easily leads to missed and redundant frames in the result. In order to solve this problem, this paper proposes a method of key frames extraction based on feature of moving target. The method reduces redundant rate and missed rate of the result set by emphasizing the features of the moving target and weakening the background features of the frame. In this method, a frame with a burst entropy change is taken as part of the key frame firstly. Then, our method extracts the SIFT points of the moving target from the frame of which the entropy value has not suddenly changed. Finally, it extracts key frames according to the entropy and SIFT distribution respectively. Experimental results show that the miss rate of this algorithm is low. At the same time, key frame results can accurately and completely describe the main content of the video.
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2018-09-03 Cooperative journals: 《干旱区研究》
Abstract：气候环境是生态健康、社会持续发展中不可控因素，而温度是维持气候系统稳定，提供人类宜居环境的重要条件。为明确宁夏地区平均气温与极端气温事件的变化特征，运用线性倾向、小波分析、相关分析等，对宁夏1962—2015年平均气温和极端气温事件进行了分析。结果表明：1962年以来宁夏全区、北部、中部干旱带及南部山区以0.38 ℃·(10a)-1、0.42 ℃·(10a)-1、0.36 ℃·(10a)-1、0.38 ℃·(10a)-1速度增温；冷暖气温主要存在20～32 a、8～19 a、2～7 a的周期，主周期13 a和32 a分别有8 a与20 a的次周期；极端低温事件频率、持续时长低于高温事件，低温四季增幅大于高温，且冬季变幅更为突出。平均气温和极端高温的升高会加大宁夏地区的干旱程度，加剧全区气候的不平衡性，极端低温指数的减少会增加农田、森林等的病虫害，使生态系统进一步恶化，应做好相应防御措施。
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-05-18 Cooperative journals: 《计算机应用研究》
Abstract： In order to combine the digital audio watermark technology with the audio content, because of the stability of the fundamental frequency of the human voice and musical instruments, this paper designed a robust audio zero-watermarking method based on the fundamental frequency of music. Firstly, the normalized subharmonic summation algorithm extracted the fundamental frequency from each frame of the audio signal. Then, the K-means algorithm encoded the extracted fundamental frequencies so as to further improve the stability of the feature. Finally, the encoded fundamental frequencies XOR with the watermark image to generate a zero watermark sequence. Besides, when the audio is maliciously tampered, it can get the inconsistent part of the audio signal by comparing the fundamental frequency information contained in the zero watermark sequence. At the inconsistent section, the algorithm can detect the maliciously tampered area. The experiment results show that the proposed algorithm has good robustness against common attacks and jitter attacks, and the results also prove that the algorithm can detect and locate the tampering.
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-04-24 Cooperative journals: 《计算机应用研究》
Abstract： In order to solve the problem of embedding capacity, imperceptibility, real-time and tampering localization in JPEG image watermarking algorithm, this paper proposes a JPEG watermarking algorithm based on entropy coding. Firstly, the algorithm locates the process of JPEG entropy coding to embed the watermarking, which can avoid the forward and reverse quantization operations and ensure that during embedding image changes is small and has good real-time performance. Secondly, according to the principle that some bits in the entropy coding process do not participate in the Huffman coding, the algorithm chooses appropriate coefficients to embed watermark. Our algorithm embeds watermarking information into the least significant bits of these coefficients to avoid the coding error caused by the modification of the Huffman coding coefficient, which should further enhance the imperceptibility of the algorithm. Experiments results show that the algorithm not only has a large embedded capacity and good imperceptibility, but also has high fragility and can accurately locate malicious tampering.
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