In this study, two modifications are proposed to mitigate drawbacks of the conventional approach of using the ‘‘Porous Media Model''(PMM) for nuclear reactor analysis. In the conventional approach, whole rea...In this study, two modifications are proposed to mitigate drawbacks of the conventional approach of using the ‘‘Porous Media Model''(PMM) for nuclear reactor analysis. In the conventional approach, whole reactor core simplifies to a single porous medium and also, the resistance coefficients that are essential to using this model are constant values. These conditions impose significant errors and restrict the applications of the model for many cases,including accident analysis. In this article, the procedures for calculating the coefficients are modified by introducing a practical algorithm. Using this algorithm will result in obtaining each coefficient as a function of mass flow rate.Furthermore, the method of applying these coefficients to the reactor core is modified by dividing the core into several porous media instead of one. In this method, each porous medium comprises a single fuel assembly. PMM with these two modifications is termed ‘‘multi-region PMM'' in this study. Then, the multi-region PMM is introduced to a new CFD-based thermo-hydraulic code that is specifically devised for combining with neutronic codes.The CITVAP code, which solves multi-group diffusion equations, is the selected as the neutronic part for this study. The resulting coupled code is used for simulation of natural circulation in a MTR. A new semi-analytic method,based on steady-state CFD analysis is developed to verify the results of this case. Results demonstrate considerable improvement, compared to the conventional approach.展开更多
提出多平台适配编码技术方案,通过动态码率分配、分辨率自适应与智能参数调优实现高效跨终端适配。技术原理上,基于H.264/H.265/AV1编码标准兼容性分析,构建场景感知的动态码率控制模型,结合关键区域(Region Of Interest,ROI)优先编码...提出多平台适配编码技术方案,通过动态码率分配、分辨率自适应与智能参数调优实现高效跨终端适配。技术原理上,基于H.264/H.265/AV1编码标准兼容性分析,构建场景感知的动态码率控制模型,结合关键区域(Region Of Interest,ROI)优先编码与人工智能驱动的量化参数(Quantizer Parameter,QP)调整,优化画质与带宽平衡;实现方法上,设计多标准并行编码框架与边缘计算协同分发网络,通过开源框架模块化扩展、容器化封装及快速UDP网络连接(Quick UDP Internet Connections,QUIC)协议低延迟传输,降低跨平台适配复杂度。展开更多
随着铁路电子客票的全面推广,亟需构建一套高效、稳定的多介质自动检票系统。文章设计并实现了一种基于大数据集群处理、近场通信(NFC,Near Field Communication)和二维码技术的铁路多介质自动检票系统,支持身份证、二维码(如铁路e卡通...随着铁路电子客票的全面推广,亟需构建一套高效、稳定的多介质自动检票系统。文章设计并实现了一种基于大数据集群处理、近场通信(NFC,Near Field Communication)和二维码技术的铁路多介质自动检票系统,支持身份证、二维码(如铁路e卡通、支付宝)、IC卡(如中铁银通卡)、人脸识别等多种检票方式;阐述了该系统的总体架构和网络架构,优化了检票业务流程,实现了联机实时检票与数据同步,并设计了3种故障应急模式保障该系统的高可用性。试验结果表明,该系统单台闸机检票速度达20人/min,可7×24h稳定运行,显著提升了客运管理效率和旅客出行体验。展开更多
针对当前互联网流媒体传输的时延敏感性问题,提出一种基于OpenFlow的SVC(scalable video coding,可分级视频编码)流媒体时延自适应分级传输方法,该方法有效结合SVC流媒体可分级和OpenFlow灵活可编程的特性,在网络带宽受限和链路拥塞的...针对当前互联网流媒体传输的时延敏感性问题,提出一种基于OpenFlow的SVC(scalable video coding,可分级视频编码)流媒体时延自适应分级传输方法,该方法有效结合SVC流媒体可分级和OpenFlow灵活可编程的特性,在网络带宽受限和链路拥塞的复杂网络环境下,通过构建基础层和增强层2个独立路由,实现了动态网络下SVC流媒体分级自适应高效传输。仿真结果表明,该方法在提升SVC流媒体传输效率和质量,改善用户体验方面有重要作用。展开更多
文摘In this study, two modifications are proposed to mitigate drawbacks of the conventional approach of using the ‘‘Porous Media Model''(PMM) for nuclear reactor analysis. In the conventional approach, whole reactor core simplifies to a single porous medium and also, the resistance coefficients that are essential to using this model are constant values. These conditions impose significant errors and restrict the applications of the model for many cases,including accident analysis. In this article, the procedures for calculating the coefficients are modified by introducing a practical algorithm. Using this algorithm will result in obtaining each coefficient as a function of mass flow rate.Furthermore, the method of applying these coefficients to the reactor core is modified by dividing the core into several porous media instead of one. In this method, each porous medium comprises a single fuel assembly. PMM with these two modifications is termed ‘‘multi-region PMM'' in this study. Then, the multi-region PMM is introduced to a new CFD-based thermo-hydraulic code that is specifically devised for combining with neutronic codes.The CITVAP code, which solves multi-group diffusion equations, is the selected as the neutronic part for this study. The resulting coupled code is used for simulation of natural circulation in a MTR. A new semi-analytic method,based on steady-state CFD analysis is developed to verify the results of this case. Results demonstrate considerable improvement, compared to the conventional approach.
文摘提出多平台适配编码技术方案,通过动态码率分配、分辨率自适应与智能参数调优实现高效跨终端适配。技术原理上,基于H.264/H.265/AV1编码标准兼容性分析,构建场景感知的动态码率控制模型,结合关键区域(Region Of Interest,ROI)优先编码与人工智能驱动的量化参数(Quantizer Parameter,QP)调整,优化画质与带宽平衡;实现方法上,设计多标准并行编码框架与边缘计算协同分发网络,通过开源框架模块化扩展、容器化封装及快速UDP网络连接(Quick UDP Internet Connections,QUIC)协议低延迟传输,降低跨平台适配复杂度。
文摘随着铁路电子客票的全面推广,亟需构建一套高效、稳定的多介质自动检票系统。文章设计并实现了一种基于大数据集群处理、近场通信(NFC,Near Field Communication)和二维码技术的铁路多介质自动检票系统,支持身份证、二维码(如铁路e卡通、支付宝)、IC卡(如中铁银通卡)、人脸识别等多种检票方式;阐述了该系统的总体架构和网络架构,优化了检票业务流程,实现了联机实时检票与数据同步,并设计了3种故障应急模式保障该系统的高可用性。试验结果表明,该系统单台闸机检票速度达20人/min,可7×24h稳定运行,显著提升了客运管理效率和旅客出行体验。
文摘针对当前互联网流媒体传输的时延敏感性问题,提出一种基于OpenFlow的SVC(scalable video coding,可分级视频编码)流媒体时延自适应分级传输方法,该方法有效结合SVC流媒体可分级和OpenFlow灵活可编程的特性,在网络带宽受限和链路拥塞的复杂网络环境下,通过构建基础层和增强层2个独立路由,实现了动态网络下SVC流媒体分级自适应高效传输。仿真结果表明,该方法在提升SVC流媒体传输效率和质量,改善用户体验方面有重要作用。
