Persistent flows are defined as network flows that persist over multiple time intervals and continue to exhibit activity over extended periods,which are critical for identifying long-term behaviors and subtle security...Persistent flows are defined as network flows that persist over multiple time intervals and continue to exhibit activity over extended periods,which are critical for identifying long-term behaviors and subtle security threats.Programmable switches provide line-rate packet processing to meet the requirements of high-speed network environments,yet they are fundamentally limited in computational and memory resources.Accurate and memoryefficient persistent flow detection on programmable switches is therefore essential.However,existing approaches often rely on fixed-window sketches or multiple sketches instances,which either suffer from insufficient temporal precision or incur substantial memory overhead,making them ineffective on programmable switches.To address these challenges,we propose SP-Sketch,an innovative sliding-window-based sketch that leverages a probabilistic update mechanism to emulate slot expiration without maintaining multiple sketch instances.This innovative design significantly reduces memory consumption while preserving high detection accuracy across multiple time intervals.We provide rigorous theoretical analyses of the estimation errors,deriving precise error bounds for the proposed method,and validate our approach through comprehensive implementations on both P4 hardware switches(with Intel Tofino ASIC)and software switches(i.e.,BMv2).Experimental evaluations using real-world traffic traces demonstrate that SP-Sketch outperforms traditional methods,improving accuracy by up to 20%over baseline sliding window approaches and enhancing recall by 5%compared to non-sliding alternatives.Furthermore,SP-Sketch achieves a significant reduction in memory utilization,reducing memory consumption by up to 65%compared to traditional methods,while maintaining a robust capability to accurately track persistent flow behavior over extended time periods.展开更多
三维软件建模凭借它真实的场景展现和其直观的视觉感受,成了三维地理信息系统(geographic information system,GIS)领域的主要研究方向。三维软件建模法构建的模型真实、美观,能非常精细地表现地物的特征和细节。通过对3Ds Max和Sketch...三维软件建模凭借它真实的场景展现和其直观的视觉感受,成了三维地理信息系统(geographic information system,GIS)领域的主要研究方向。三维软件建模法构建的模型真实、美观,能非常精细地表现地物的特征和细节。通过对3Ds Max和Sketch Up两种不同三维软件建模方法的比较分析,总结出两种软件各自的优势,然后将两者的优点相结合,能更加快速完整地进行三维模型构建。通过对联合建模方法的研究,能够为三维软件建模提供一种更为简洁的方法,从而缩短建模的时间,减少人力消耗。展开更多
计算机辅助设计在建筑行业的普及,给建筑设计从业人员带来了史无前例的便捷性。建筑效果图作为建筑在设计表达阶段的一个重要组成部分,往往也给许多设计师带来了绘制上的困扰。V-Ray for Sketch Up的诞生在很大程度上方便了设计师的工作...计算机辅助设计在建筑行业的普及,给建筑设计从业人员带来了史无前例的便捷性。建筑效果图作为建筑在设计表达阶段的一个重要组成部分,往往也给许多设计师带来了绘制上的困扰。V-Ray for Sketch Up的诞生在很大程度上方便了设计师的工作,它的存在使制作建筑效果图变得简单,让每一个设计师都能够自己参与进来。文章将从实际出发来探讨V-Ray 3.40 for Sketch Up在建筑设计中的应用,得出此软件会在一定程度上提高建筑设计工作者的工作效率的结论,具有一定的推广应用意义。展开更多
基金supported by the National Undergraduate Innovation and Entrepreneurship Training Program of China(Project No.202510559076)at Jinan University,a nationwide initiative administered by the Ministry of Educationthe National Natural Science Foundation of China(NSFC)under Grant No.62172189.
文摘Persistent flows are defined as network flows that persist over multiple time intervals and continue to exhibit activity over extended periods,which are critical for identifying long-term behaviors and subtle security threats.Programmable switches provide line-rate packet processing to meet the requirements of high-speed network environments,yet they are fundamentally limited in computational and memory resources.Accurate and memoryefficient persistent flow detection on programmable switches is therefore essential.However,existing approaches often rely on fixed-window sketches or multiple sketches instances,which either suffer from insufficient temporal precision or incur substantial memory overhead,making them ineffective on programmable switches.To address these challenges,we propose SP-Sketch,an innovative sliding-window-based sketch that leverages a probabilistic update mechanism to emulate slot expiration without maintaining multiple sketch instances.This innovative design significantly reduces memory consumption while preserving high detection accuracy across multiple time intervals.We provide rigorous theoretical analyses of the estimation errors,deriving precise error bounds for the proposed method,and validate our approach through comprehensive implementations on both P4 hardware switches(with Intel Tofino ASIC)and software switches(i.e.,BMv2).Experimental evaluations using real-world traffic traces demonstrate that SP-Sketch outperforms traditional methods,improving accuracy by up to 20%over baseline sliding window approaches and enhancing recall by 5%compared to non-sliding alternatives.Furthermore,SP-Sketch achieves a significant reduction in memory utilization,reducing memory consumption by up to 65%compared to traditional methods,while maintaining a robust capability to accurately track persistent flow behavior over extended time periods.
文摘三维软件建模凭借它真实的场景展现和其直观的视觉感受,成了三维地理信息系统(geographic information system,GIS)领域的主要研究方向。三维软件建模法构建的模型真实、美观,能非常精细地表现地物的特征和细节。通过对3Ds Max和Sketch Up两种不同三维软件建模方法的比较分析,总结出两种软件各自的优势,然后将两者的优点相结合,能更加快速完整地进行三维模型构建。通过对联合建模方法的研究,能够为三维软件建模提供一种更为简洁的方法,从而缩短建模的时间,减少人力消耗。
文摘计算机辅助设计在建筑行业的普及,给建筑设计从业人员带来了史无前例的便捷性。建筑效果图作为建筑在设计表达阶段的一个重要组成部分,往往也给许多设计师带来了绘制上的困扰。V-Ray for Sketch Up的诞生在很大程度上方便了设计师的工作,它的存在使制作建筑效果图变得简单,让每一个设计师都能够自己参与进来。文章将从实际出发来探讨V-Ray 3.40 for Sketch Up在建筑设计中的应用,得出此软件会在一定程度上提高建筑设计工作者的工作效率的结论,具有一定的推广应用意义。
