To mitigate Distributed Denial-of-Service (DDoS) attacks towards enterprise networks, we study the problem of scheduling DDoS traffic through on-premises scrubbing at the local edge and on-demand scrubbing in the remote clouds. We model this problem as a nonlinear mixed- integer program, which is characterized by the inputs of arbitrary dynamics and the trade-offs between staying at suboptimal scrubbing locations and using different best locations with switching overhead. We first design a prediction-oblivious online algorithm which consists of a carefully-designed fractional algorithm to pursue the long-term total cost minimization but avoid excessive switching overhead over time, and a randomized rounding algorithm to derive the flow-based, integral decisions. We next design a prediction-aware online algorithm which leverages the predicted inputs and can make even better scheduling decisions through invoking our prediction-oblivious online algorithm and improving its solutions via re-solving the original problem slice over each prediction window. We further extend our study to prioritize local scrubbing, and adapt our algorithms to this case correspondingly. Then, we rigorously prove the worst-case, constant competitive performance guarantees of our online algorithms. Finally, we conduct extensive evaluations and validate the superiority of our approach over multiple existing alternatives approaches.

铜及铜合金水平连铸坯内部通常存在气孔、疏松、裂纹等缺陷,严重影响产品质量和成材率.基于超声波检测原理结合C扫描成像技术和多通道扫描技术可对各类铸坯缺陷进行精确检测和实时显示.设计开发了可在线往复检测的超声检测设备,并对水平连铸铜板带坯在线检测结果进行验证.对检测异常处采取了金相试验,以此确认检测异常处是否为缺陷,从而验证设备检测结果的准确性.收集后续铜板带成材率数据,并与在线检测数据进行对比分析,给出了两者之间的相互联系.在线超声检测设备拥有检测数据可实时反馈以及检测精度高等优点,能为企业的实际生产与决策提供数据参考.

针对铜管坯的孔洞、夹杂、裂纹、壁厚不均匀等常见缺陷难以在线检测的问题,引入超声波无损检测技术,设计开发了一套应用于熔铸现场的超声在线检测系统.结合铜管坯水平连铸工序对探伤的实际需求,设计多组体积缺陷、线缺陷、几何缺陷检测探头,实现对孔洞、裂纹、壁厚均匀性的在线检测.针对检测出来的铸坯缺陷数据和水平连铸实时工艺参数,开发了一套数据库管理系统,实现对水平连铸工序中多种数据的整合汇总和初步分析,为建立铸坯缺陷和工艺参数之间的关系,提供了一个信息化、智能化的数据库管理工具.

目前,键合铜丝因其价格低廉、具有优良的材料性能等特点正逐渐替代键合金丝广泛应用于电子封装领域.本文对当前市场上应用的金丝、铜丝、银丝及铝丝性能特点进行了分析对比,探讨了以键合铜丝替代传统键合丝材料的优势;简要介绍了铜丝材制备和键合过程的研究进展,并对键合铜丝的封装失效形式进行了简要分析;综述了微合金化对键合铜丝服役性能的影响规律及机理;最后从市场需求及理论研究方面分析了键合铜丝市场的发展趋势.

在5G通信技术及消费电子行业快速发展的背景下,铜基薄壁热管被广泛应用于大功率电子设备散热领域.通过介绍目前应用较广的几种热管,对其结构、特点及应用范围进行了对比;阐述热管在加工制备和使用过程中存在的一些问题和缺陷,对表面缺陷形成机理进行分析,并对热管未来的发展趋势进行了展望.

铜加工材的铸坯内部常存在气孔、缩孔等空洞缺陷,在后续加工过程中,这些空洞缺陷常演变为内部裂纹或表面缺陷,导致成品率降低.在生产过程中,可借助变形和升温来消除铸坯内部的空洞缺陷.空洞的形变闭合是消除缺陷的先决条件,因此有必要开展铜合金中空洞缺陷的形变演化研究.本文对金属空洞缺陷形变演化的研究进展进行了梳理;基于对某锡磷青铜连铸板坯内部空洞缺陷及铸态组织的观察,重点讨论了现有研究成果对于铜合金的适用性,指出了材料微观结构对空洞缺陷形变演化的潜在影响;针对当前研究在几何建模方面的难点,采用Python语言设计了含任意椭球空洞的体元模型自动建模程序.

为了适应电子产品轻薄化、小型化的发展需求,压扁型薄壁烧结热管由于其优异的传热性能得到广泛应用,5G技术的应用导致电子产品内部热流密度的大幅度提高,对热管散热性能提出了更高的要求.烧结热管进行压扁工序时容易出现表面局部凹坑缺陷,这种表面凹坑会降低热管的表面质量,降低热管传热性能.本文通过光学显微镜(OM)、电子背散射衍射(EBSD)和白光干涉试验对热管压扁表面局部凹坑位置进行宏观形貌和微观组织分析,并且采用万能拉伸实验机对烧结热管进行力学性能测试.结果表明:烧结后热管内部再结晶晶粒明显长大,局部异常长大晶粒尺寸达到2.17 mm,在壁厚方向上仅为一层晶粒,呈现"饼状"的长大方式;基体形成强烈的再结晶织构,并且分布着具有异常取向的条带状退火孪晶;异常长大晶粒和退火孪晶对热管组织造成的尺寸不均匀和取向不均匀是导致烧结热管局部凹坑的主要原因.同时,异常长大的晶粒会导致烧结热管的屈服强度、抗拉强度和延伸率的下降.

利用真空熔炼炉制备得到Cu-2.36Ni-0.60Si-0.13Mg-0.059Zn合金铸锭,采用热锻开坯、 再进行热轧得到厚度为12 mm的合金板材,然后经过多道次冷轧得到厚度为1 mm的合金带材,并对其进行不同条件下的时效处理.采用光学金相(OM)、电子背散射衍射(EBSD)、力学性能测试和电学性能测试等手段对合金带材冷轧及时效过程进行微观组织、力学性能和电导率测试.结果表明:随着轧制变形量的不断增加,初始组织向纤维状转变,晶粒破碎,合金硬度升高,当轧制变形量为90％时,显微硬度可达203.8 HV;冷轧板材经过450℃保温6 h时效处理后,可获得较好的综合性能(显微硬度达到281.4 HV,电导率达到46.4％IACS);随着时效温度的升高,第二相的尺寸明显增大,由9.0 nm增大至24.9 nm,且时效处理后基体高斯(Goss)和Z形织构转变为旋转立方(R-cube)和高斯(Goss)织构.

To mitigate Distributed Denial-of-Service (DDoS) attacks towards enterprise networks, we study the problem of scheduling DDoS traffic through on-premises scrubbing at the local edge and on-demand scrubbing in the remote clouds. We model this problem as a nonlinear mixed-integer program, which is characterized by the inputs of arbitrary dynamics and the trade-offs between staying at suboptimal scrubbing locations and using different best locations with switching overhead. We first design a prediction-oblivious online algorithm which consists of a carefully-designed fractional algorithm to pursue the long-term total cost minimization but avoid excessive switching overhead over time, and a randomized rounding algorithm to derive the flow-based, integral decisions. We next design a prediction-aware online algorithm which leverages the predicted inputs and can make even better scheduling decisions through invoking our prediction-oblivious online algorithm and improving its solutions via re-solving the original problem slice over each prediction window. We further rigorously prove the worst-case, constant competitive performance guarantees of our online algorithms. We finally conduct extensive evaluations and validate the superiority of our approach over multiple existing alternatives.

传统的拉拔模具库配模过程存在过度依赖人工操作和经验、信息更新难度大、配模效率低等问题,本文设计和开发了一套面向企业模具库的智能化信息管理系统.此系统运用了先进的Spring Boot、Vue和Hibernate技术框架,用户对Vue编写的前端界面进行操作,前端界面嵌入拉拔算法,后端Spring Boot架构实现信息接收请求并处理,处理值反馈到前端与用户交互,并通过Hibernate技术将模具信息封装、更新完保存到数据库.此外,通过外模和游芯管理模块、配模工作台模块、借模登记表和归还登记表四个主要模块实现以上架构设计.实践证明,该系统的界面友好、运行稳定,能有效提高拉拔模具库管理效率,保证了铜管生产质量.

A company uses graphite mold to produce red copper plate and strip in double flow horizontal continuous casting mold.Taking graphite mold as the research object, through comparison and analysis of billet temperature, quality and organization, it is found that the temperature of double flow A and B belts produced with 3# graphite mold is relatively uniform, the yield is high, the overall grain size is small, and the number of grains is large. On this basis, the relationship between the physical parameters of graphite and the slab temperature is revealed through finite element simulation, that is, with the increase of the thermal conductivity of graphite,the heat released by the solidification of the slab increases, the slab temperature decreases, and the wall temperature of the graphite plate increases; There is no direct relationship between graphite density and slab temperature, so it needs to work with other physical parameters to adjust slab quality.

为满足车联网中海量数据的采集、传输以及对这些数据的快速处理的需求,可采用移动边缘计算(MEC)技术.本文考虑移动边缘计算中基站连接方式和物理资源的特点,对边缘服务器的部署问题进行了分析,以部署成本和网络时延为优化目标,划分基站集群,并使用整数线性规划(ILP)建立模型.为了获得运行效率更高的边缘服务器部署方案,本文使用分支定界算法和启发式贪婪算法获得优化模型的近似最优解.实验评估结果显示,分支定界算法和启发式贪婪算法最高可以把边缘服务器部署算法运行时间减少37.6％.此外,本文分析了用户服务器请求数量和用户服务优先级对算法运行时间和边缘服务器运行成本的影响.

对近年来引线框架用铜镍硅合金种类和性能进行了综述,并阐述了铜镍硅合金相关强化机制.重点总结了铜镍硅合金力学性能和电导率与Ni、Si含量及不同微量元素添加之间的关系,同时简要介绍铜镍硅合金制备工艺及成形技术的发展现状.提出未来铜镍硅合金性能应满足强度达到750～840MPa,电导率达到35％IACS,其制备技术将向着高新技术集成化,规模化,绿色化方向发展.

为了解决现有时间序列的分段线性表示方法忽略时间序列的全局特征, 局限于局部最优的问题, 本文通过研究时间序列的趋势, 发现了时间序列的波动特性, 将时间序列的趋势变化分为上下两层, 在上下两层分别剔除趋势保持点. 实验结果表明, 该分段方法时间复杂度低、且易于实现, 在保持时间序列趋势特征的基础上, 得到的拟合误差更小.

Following M.Abate and A.Saracco's work on strongly pseudoconvex domains in ℂ^n, we characterize Carleson measures of A^2(D) in bounded convex domains with smooth boundary of finite type. We also give examples of Carleson measures with uniformly discrete (with respect to the Kobayashi distance) sequences.

More and more mobile devices and applications are beginning to use undirected networks. In order to improve the user experience and ensure the quality of network services, edge computing is proposed, which is also an important part of the fifth generation network. As a key technology of 5G networks, NFV and SDN are receiving more and more attention. NFV uses virtualization technology to flexibly deploy network services. At the same time, SDN can provide all information about network topology and resources. The combination of NFV and SDN provides a new approach to network service deployment in edge computing. Due to the performance limitations of the edge server, when the users and devices accessing the network increase, if the edge server cannot provide the corresponding network resources, the network service quality will be degraded. This paper proposes a dynamic virtual network service placement scheme based on network service type, summarizes the characteristics of different network service types for network resource usage, determines the service type when users request network services, and proposes to ensure the optimal utilization of network resources and network delay. The algorithm is dynamically placed and the feasibility of the proposed scheme is proved by experiments.

具有一定曲率外形的铝合金整体壁板属于典型的多筋零部件,传统弯曲成形工艺成形困难,容易产生多种缺陷.提出了离散填料辅助滚弯成形整体2A12T4铝合金壁板滚弯工艺,并通过实验与整体填料滚变成形进行了对比,同时采用有限元模拟技术,探究了离散填料辅助整体壁板滚弯成形中的影响因素.研究结果表明:填料数量、上下垫板厚度等因素对成形性能影响较大,填料在3～6块时成形稳定,可以有效地避免筋条屈曲与失稳;随垫板厚度增加,壁板表面圆弧更加光滑、连续,但是回弹性增强;上下垫板分别在10～20 mm厚度时,综合性能较好.通过离散填料辅助滚弯技术可以成形出质量较高的整体壁板.

锆合金带材是核电中常用结构材料,影响其冲压成形性的因素有很多.本文采用有限元模拟的方法,结合典型的冲压件结构,重点研究材料性能参数对锆合金带材冲压成形的影响.结果表明,工件接近底面圆角处厚度最小,减薄最多,为最容易开裂位置;冲压过程有限元模拟预测裂纹位置与实际相符,在凸模圆角处为双向拉伸;在凹模圆角处介于纯剪切与单向拉伸之间;在近凸模圆角位置为单向拉伸而后转为平面状态,到达破裂区.当材料各向异性参数r值一定时,随着硬化指数n值增大,壁厚减薄越少,壁厚分布更均匀;n值一定时,塑性应变比各向异性度Δr较小的带材冲压时破裂倾向也较小.所以控制带材的硬化能力和各向异性行为可改善带材冲制性能.

针对新一代信息技术的发展和航空航天领域智能制造的应用需求,通过分析数控系统的技术趋势,建立了开放式、智能化数控系统的多维度需求框架,提出了开放式、智能化数控系统的可重构数控系统平台、基于信息终端的工艺链集成以及基于工业大数据产品生命周期管理体系结构,研制出“蓝天数控”系统,并通过航空制造领域典型零件的加工控制应用实践,探索了实现开放式、智能化数控系统的实现路径.

假设D是一个其边界为拟圆周的平面有界单连通区域,Pε是一个几乎填满D的半径为ε的正则六边形圆填充,则在单位圆盘U内存在一个组合等价于Pε的圆填充.众所周知,当ε → 0时,D内半径为ε的圆与U内对应的圆之间的离散规范化映射fε整体一致收敛于Riemann映射f:D→U.本文将给出这个整体收敛fε→f的速度估计.