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Joint Content Caching and Fetching Scheme with Cooperative Transmission in Hierarchical Networks

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China Communications 2023年第3期20卷 146-160页

作者： Jizhe Zhou Guangchao Wang kaifeng han Ying Du Zhiqin Wang Wenbo Wang China Academy of Information and Communications Technology Beijing 100191China Beijing University of Posts and Telecommunications Beijing 100876China

Concerned with the surge of contentcentric applications,it is challenging to balance network traffic and cater to low-delay *** caching architecture of both edge network(EN)and core network(CN)emerges and leverages caching resources to reduce the delivery delay of *** previous work takes an impractical assumption to treat the CN as a content provider,which neglects the collaboration by intermediate CN *** importantly,it is still necessary to thoroughly study the tradeoff between CN delay and edge delay for files delivery so as to minimize the overall delivery delay across the *** this paper,we consider a hierarchical caching network with distributed CN nodes and edge nodes,where cooperative transmission is enabled for edge nodes to transmit multi-files *** poses a joint optimization problem of hierarchical file caching and fetching to minimize the overall delivery delay of *** the problem is NP-hard,we decompose the original problem and design an iterative algorithm to address *** results validate that the proposed scheme can find a balanced solution between lowering edge delay by utilizing coordinated CN caching and lowering CN delay by solely relying on edge caching.

关键词： hierarchical caching content distribution

Numerical Study of Elastic Wave Propagation Characteristics in Cracked Rock

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Journal of Applied Mathematics and Physics 2014年第6期2卷 391-396页

作者： kaifeng han Ruiqi Cao College of Optoelectronic Science and Engineering National University of Defense Technology Changsha Hunan 410073 China

Numerical methods can provide extremely powerful tools for analysis and design of engineering systems with complex factors that are not possible or very difficult with the use of the conventional methods. In this paper, we use the 2-D boundary element method (BEM) program to model elastic wave excited by a point explosive source propagating in cracked rocks. As an example, we consider the typical crack distributions in rocks, both models for the real crack structure are also talked about. The elastic wave propagating in rocks with aligned cracks and parallel fractures is assumed. Effects of different crack parameters, such as crack scale length and crack density are analyzed. Numerical results show that the BEM is a powerful interpretive tool for understanding the complicated wave propagation and interaction in cracked solids.

关键词： Numerical Study Elastic Wave Propagation Characteristics Cracked Rock Boundary Element Method

Superplastic Forming and Diffusion Bonding for Sandwich Structure of Ti-6Al-4V Alloy

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Journal of Materials Science & Technology 2005年第1期21卷 60-62页

作者： Wenbo han, kaifeng ZhanG, Guofeng WANG and Xiaojun ZhanGSchool of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, ChinaProf., Ph.D., Sch. of Mat. Sci. and Eng. Harbin Inst. of Technol. Harbin 150001 China

Superplastic forming and diffusion bonding (SPF/DB) is a well-established process for the manufacture of components almost exclusively from Ti-6AI-4V sheet material. The sandwich structure of Ti-6AI-4V alloy is investigated. The effects of the microstructure on the SPF/DB process were discussed. The microstructure at the interfaces and the distribution of thickness were researched.

关键词： Superplastic forming Diffusion bonding Sandwich structure TI-6A1-4V alloy

Synthesis and Enhanced Superplasticity of the Zirconia-dispersed Alumina Nanocomposite

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Journal of Materials Science & Technology 2005年第1期21卷 79-82页

作者： Guoqing CHEN, kaifeng ZhanG, Wenbo han and Junting LUOSchool of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, ChinaProf., Ph.D., Sch. of Mat. Sci. and Eng. Harbin Inst. of Technol. Harbin 150001 China

A series of alumina-zirconia composites with various grain sizes were prepared from the nano-sized powders with different agglomerations. Microstructural analysis of the sintered compacts indicates that the as-sintered material is a typical intra/inter granular nanocomposite with uniform distribution of the zirconia grains in the alumina matrix. Superplastic deep drawing test under different conditions demonstrates that dense Al2O3/ZrO2 samples with average grain size of 230 nm can be elongated to a dome height of at least 12 mm at the punch rate of 0.6 mm·min-1 at 1400℃. Further drawing tests show that for the composites with larger grain size, such elongation cannot be achieved at such a strain rate.

关键词： Nanocomposite Synthesis Microstructure Superplasticity

Resonant Modes of One-Dimensional Metamaterial Containing Helmholtz Resonators with Point Defect

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Journal of Modern Physics 2017年第10期8卷 1737-1747页

作者： Dongbao Gao Xinwu Zeng Xuanjun Liu kaifeng han Academy of Ocean Science and Engineering National University of Defense Technology Changsha China

The metamaterial constructed by Helmholtz resonators (HR) has low-frequency acoustic forbidden bands and possesses negative mass density and effective bulk modulus at particular frequencies. The resonant modes in one-dimensional HR structure with point defect were studied using finite element method (FEM). The results show that the acoustic energy is localized between the resonant HR and the opening in the local-resonant-type gap. There is a high pressure area around the defect resonator at the frequency of defect mode. In the Bragg type gap, the energy mainly distributes in the waveguide with harmonic attenuation due to the multi-scattering. Phase opposition demonstrates the existence of negative dynamic mass density. Local negative parameter is observed in the pass band due to the defect mode. Based on further investigation of the acoustic intensity and phase distributions in the resonators corresponding to two different forbidden bands, only one local resonant mode is verified, which is different from the three-component local resonant phononics. This work will be useful for understanding the mechanisms of acoustic forbidden bands and negative parameters in the HR metamaterial, and of help for designing new functional acoustic devices.

关键词： Helmholtz Resonator Metamaterial Resonant Mode Point Defect Local Negative Parameters Phase Distribution

Vision, application scenarios, and key technology trends for 6G mobile communications

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Science China(Information Sciences) 2022年第5期65卷 5-31页

作者： Zhiqin WANG Ying DU Kejun WEI kaifeng han Xiaoyan XU Guiming WEI Wen TONG Peiying ZHU Jianglei MA Jun WANG Guangjian WANG Xueqiang YAN Jiying XIANG He HUANG Ruyue LI Xinhui WANG Yingmin WANG Shaohui SUN Shiqiang SUO Qiubin GAO Xin SU China Academy of Information and Communications Technology Huawei Technologies Canada Co. Ltd. Huawei Technologies Co. Ltd.(Hangzhou) Huawei Technologies Co. Ltd.(Chengdu) Huawei Technologies Co. Ltd.(Shanghai) ZTE Corporation Datang Mobile Communications Equipment Co. Ltd.

With the global commercialization of the fifth-generation(5G) network, many countries, including China, USA, European countries, Japan, and Korea, have started exploring 6G mobile communication network, following the tradition of “planning the next while commercializing one generation”. Currently,studies on 6G networks are at the infancy stage. Research on the vision and requirements for 6G is still ongoing, and the industry is yet to clarify the key enabling technologies for 6G. However, 6G will certainly build on the success of 5G. Therefore, developing high-quality 5G networks and seamlessly integrating 5G with verticals are the priorities before 2030, when 6G is projected to be commercialized. Also, global 5G standards will keep evolving to better support vertical applications. As a milestone, the Third-Generation Partnership Project(3GPP) published Release 16 in July 2020, which continuously enhanced the capabilities of mobile broadband service based on Release 15 and realized the support for low-delay and high-reliability applications, such as Internet of Vehicles and industrial Internet. Currently, 3GPP is working on Releases 17 and 18, focusing on meeting the demands of medium-and high-data-rate machine communication with low-cost and high-precision positioning, which will be published in June 2022. Thus, 6G networks will further expand the application fields and scope of the Internet of Things to accommodate those services and applications that are beyond the capabilities of 5G networks. Herein, we present our vision, application scenarios,and key technological trends for 6G networks. Furthermore, we propose several future research opportunities in 6G networks with regard to industrialization and standardization.

关键词： sixth-generation (6G) mobile communication holographic radio technology 6G vision application scenarios of 6G terahertz communication integrated sensing and communication integrated intelligence and communication ultra-massive MIMO reconfigurable intelligent surface co-frequency co-time full-duplex

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基于块对角化的通信雷达频谱共存设计

通信学报 2021年第12期42卷 226-235页

作者：韩凯峰黄立涛陈力王志勤中国信息通信研究院移动通信创新中心北京100191 中国科学技术大学电子工程与信息科学系安徽合肥230026

针对通信与雷达同频共存问题,提出了基于块对角化的波束设计方案。首先,在保证不对雷达设备造成干扰和满足功率限制的前提下,构建最大化通信系统和速率的优化问题。为求解该问题,引入了通信用户间干扰为0的约束,使非凸的原问题具备解析... 详细信息

针对通信与雷达同频共存问题,提出了基于块对角化的波束设计方案。首先,在保证不对雷达设备造成干扰和满足功率限制的前提下,构建最大化通信系统和速率的优化问题。为求解该问题,引入了通信用户间干扰为0的约束,使非凸的原问题具备解析解。根据引入约束带来的关于通信基站发射天线数的限制,提出了另外2种算法进一步考虑当不满足限制条件时的块对角化设计。仿真结果表明,所提算法能在各种场景下引入约束使原问题有解,计算复杂度较低,具备较高的实际工程应用价值。

关键词：频谱共享通信雷达频谱共存块对角化用户选择

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研究生应掌握的八种研究方法

学位与研究生教育 2008年第9期 29-31页

作者：周树智韩凯峰西北大学公共政策研究所西安710069 西北大学研究生处西安710069

对理论与实践相结合的选题方法、读书和文献研究方法等八种研究生应掌握的基本方法进行了分析和讨论。

关键词：研究生研究方法

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二维随机孔隙岩石模型及其波场分析

岩石力学与工程学报 2008年第A2期27卷 3498-3502页

作者：韩开锋曾新吾国防科技大学光电科学与工程学院

建立非均匀介质中随机孔隙岩石模型,引入局部半径(r)和局部孔隙密度(p)两个模型参数。用局部半径(r)表示每一个孔隙分布区的半径,用局部孔隙密度(p)表示孔隙介质在各个孔隙分布区中所占空间的百分比。这个模型可以模拟孔隙尺度具有空间... 详细信息

建立非均匀介质中随机孔隙岩石模型,引入局部半径(r)和局部孔隙密度(p)两个模型参数。用局部半径(r)表示每一个孔隙分布区的半径,用局部孔隙密度(p)表示孔隙介质在各个孔隙分布区中所占空间的百分比。这个模型可以模拟孔隙尺度具有空间统计分布的随机孔隙岩石介质,并将随机介质模型参数(r,p)与孔隙介质的宏观特性(弹性波速度)直接联系起来。结果表明,选择合适的模型参数能够描述实际复杂的孔隙岩石介质。不同形式的随机孔隙岩石模型中纵波速度和横波速度的变化程度各不相同。弹性波速度相对于大孔隙的响应更容易分辨,在一定的局部孔隙密度和局部半径下,孔隙分布的相对位置变化对波速几乎没有影响。横波对随机孔隙岩石的分辨率比纵波高,横波对随机介质各向异性,特别是对微裂隙相当敏感。

关键词：岩石力学孔隙尺度随机介质弹性波局部半径自相关函数