For the traditional steganographic method of Jsteg, the emmbedment of secret message is completed by dividing cover-image into nonoverlapping blocks of 8×8 pixels, discrete cosine transform （DCT） transforming, ...For the traditional steganographic method of Jsteg, the emmbedment of secret message is completed by dividing cover-image into nonoverlapping blocks of 8×8 pixels, discrete cosine transform （DCT） transforming, and using the standard 8×8 quantization table to quantize. In this paper, a novel steganographic method based on the JPEG quantization table modification is presented. Instead of dividing cover-image into 8×8 blocks, nonoverlapping blocks of 16×16 pixels is used. Both theoretical anlysis and experiment results show that the new methods has larger steganography capacity and better stego-image quality, compared with the method of Jsteg and Chang＇s展开更多
A new two-stage soft real-time scheduling algorithm based on priority table was proposed for task dispatch and selection in cluster systems with inaccurate parameters. The inaccurate characteristics of the system were...A new two-stage soft real-time scheduling algorithm based on priority table was proposed for task dispatch and selection in cluster systems with inaccurate parameters. The inaccurate characteristics of the system were modeled through probability analysis. By taking into account the multiple important system parameters, including task deadline, priority, session integrity and memory access locality, the algorithm is expected to achieve high quality of service. Lots of simulation results collected under different load conditions demonstrate that the algorithm can not only effectively overcome the inaccuracy of the system state, but also optimize the task rejected ratio, value realized ratio, differentiated service guaranteed ratio, and session integrity ensured ratio with the average improvement of 3.5%, 5.8%, 7.6% and 5. 5%, respectively. Compared with many existing schemes that cannen deal with the inaccurate parameters of the system, the proposed scheme can achieve the best system performance by carefully adjusting scheduling probability. The algorithm is expected to be promising in systems with soft real-time scheduling requirement such as E-commerce applications.展开更多
为应对自然风随机性与波动性带来的风速预测精度低的问题,提出一种基于频-时转换与Informer的强风等级预测方法(a strong-wind level prediction method with frequency-time transformation and Informer,FT-Informer)。该方法通过预...为应对自然风随机性与波动性带来的风速预测精度低的问题,提出一种基于频-时转换与Informer的强风等级预测方法(a strong-wind level prediction method with frequency-time transformation and Informer,FT-Informer)。该方法通过预测强风等级并输出包含多级强风信息的风速等级概率分布表,提升高铁系统在强风环境下的调度能力。首先,将Informer作为主要预测器,基于编码器-解码器架构和自注意力机制,预测实时风速。然后,引入频-时转换(frequency-time trans-formation,FT)方法对预测风速的随机脉动特性进行数值分析,进而实现风速波动范围的遍历模拟,降低风速波动性对预测结果的干扰。最后,为提供更具决策支持性的大风预警信息,构建预测风速的概率密度函数(probability density function,PDF)样本矢量集,模拟随机脉动风场的全概率尺度,从而生成未来一段时间内风速等级的概率分布表。实验结果表明,所提出的预测方法在风速等级预测精度上明显优于其他5种模型。其中预测准确率提高0.64%~10.36%,预测等级偏差为1的误差率降低0.36%~6.78%。值得注意的是,所提方法预测等级偏差为2的概率为0,与其他模型相比预测效果提升0.19%~3.68%。此外,在不同时间间隔及不同数据集的泛化实验中,该方法均展现出较强的鲁棒性和泛化性,在功率谱拟合度实验(power spectrum fitting experiment)以及风速概率精度对比实验中,验证了各强风等级概率计算结果的有效性。研究方法不仅降低了随机脉动风对预测结果的干扰,还为铁路调度人员提供未来一段时间内铁路沿线3个强风等级的发生概率,助力铁路部门制定更加精准且细致的调度决策,从而为列车在强风环境下的安全运营提供有力保障。展开更多
在智能电网通信架构持续演化的背景下,变电站对信息流控制系统提出高密度并发、精细调度与异常自愈等多重能力要求,推动软件定义网络(Software Defined Network,SDN)技术向变电站场景深入渗透。本研究构建一套基于SDN架构的变电站智能...在智能电网通信架构持续演化的背景下,变电站对信息流控制系统提出高密度并发、精细调度与异常自愈等多重能力要求,推动软件定义网络(Software Defined Network,SDN)技术向变电站场景深入渗透。本研究构建一套基于SDN架构的变电站智能化信息流控制系统,围绕转发结构重构、状态动态建模、资源分配优化与故障联动反馈4个维度展开系统性设计,形成由控制器统一调度、策略解析层动态编排、转发执行层实时响应的分层联控体系。测试结果表明,该系统在多个方面均优于传统架构,可为构建柔性可编程的变电站通信平台提供方法与路径。展开更多
基金Supported by the National Natural Science Foundation of China(50803016)the Fundamental Research Funds for the Central Universities
文摘For the traditional steganographic method of Jsteg, the emmbedment of secret message is completed by dividing cover-image into nonoverlapping blocks of 8×8 pixels, discrete cosine transform （DCT） transforming, and using the standard 8×8 quantization table to quantize. In this paper, a novel steganographic method based on the JPEG quantization table modification is presented. Instead of dividing cover-image into 8×8 blocks, nonoverlapping blocks of 16×16 pixels is used. Both theoretical anlysis and experiment results show that the new methods has larger steganography capacity and better stego-image quality, compared with the method of Jsteg and Chang＇s
基金Project(60573127) supported by the National Natural Science Foundation of China project(05JJ40131) supported by theNatural Science Foundation of Hunan Province
文摘A new two-stage soft real-time scheduling algorithm based on priority table was proposed for task dispatch and selection in cluster systems with inaccurate parameters. The inaccurate characteristics of the system were modeled through probability analysis. By taking into account the multiple important system parameters, including task deadline, priority, session integrity and memory access locality, the algorithm is expected to achieve high quality of service. Lots of simulation results collected under different load conditions demonstrate that the algorithm can not only effectively overcome the inaccuracy of the system state, but also optimize the task rejected ratio, value realized ratio, differentiated service guaranteed ratio, and session integrity ensured ratio with the average improvement of 3.5%, 5.8%, 7.6% and 5. 5%, respectively. Compared with many existing schemes that cannen deal with the inaccurate parameters of the system, the proposed scheme can achieve the best system performance by carefully adjusting scheduling probability. The algorithm is expected to be promising in systems with soft real-time scheduling requirement such as E-commerce applications.
文摘在智能电网通信架构持续演化的背景下,变电站对信息流控制系统提出高密度并发、精细调度与异常自愈等多重能力要求,推动软件定义网络(Software Defined Network,SDN)技术向变电站场景深入渗透。本研究构建一套基于SDN架构的变电站智能化信息流控制系统,围绕转发结构重构、状态动态建模、资源分配优化与故障联动反馈4个维度展开系统性设计,形成由控制器统一调度、策略解析层动态编排、转发执行层实时响应的分层联控体系。测试结果表明,该系统在多个方面均优于传统架构,可为构建柔性可编程的变电站通信平台提供方法与路径。
