Preparation and electrochemical characterization of Ti-based amorphous metallic glass with high strength

Ti-based amorphous metallic glasses have excellent mechanical, physical, and chemical properties, which is an important development direction and research hotspot of metal composite reinforcement. As a stable, simple, efficient, and large-scale preparation technology of metallic powders, the gas atomization process provides an effective way of preparing amorphous metallic glasses. In this study, the controllable fabrication of a Ti-based amorphous powder, with high efficiency, has been realized by using gas atomization. The scanning electron microscope, energy-dispersive spectrometer, and X-ray diffraction are used to analyze surface morphology, element distribution, and phase structure, respectively. A microhardness tester is used to measure the mechanical property. An electrochemical workstation is used to characterize corrosion behavior. The results show that as-prepared microparticles are more uniform and exhibit good amorphous characteristics. The mechanical test shows that the hardness of amorphous powder is significantly increased as compared with that before preparation, which has the prospect of being an important part of engineering reinforced materials. Further electrochemical measurement shows that the corrosion resistance of the as-prepared sample is also significantly improved. This study has laid a solid foundation for expanding applications of Ti-based metallic glasses, especially in heavy-duty and corrosive domains.     

基于深度学习的视频跟踪研究进展综述

近年来深度学习迅猛发展，颠覆了语音识别、图像分类、文本理解等领域的算法设计思路。深度学习因其具备强大的特征提取能力，在图像识别领域的成绩尤为突出。然而深度学习与视频监控领域的结合并不多，由于深度模型具有多层网络结构，算法复杂度大，训练和更新模型时比较耗时，很难满足实时性要求。回顾了深度学习的发展史，介绍了最近10年来国内外深度学习主要模型，论述了基于深度学习的目标跟踪算法，指出了各算法的优缺点，最后对当前该领域存在的问题和发展前景进行了总结和展望。     

行波管质量与可靠性信息管理系统的设计

本文从应用角度简要介绍了《行波管质量与可靠性信息管理系统》的研制背景，数据库的数据来源，数据结构，系统构成及功能特点。     

媒体服务中流式拷贝性能分析

随着网络带宽的进一步提高,视频点播的瓶颈基本卡在视频服务器端。文章提供的服务器端的流式拷贝,能进一步提高整个系统的服务能力。文章对流式拷贝的过程进行描述,对其中的数学模型进行分析,并与没有流式拷贝的系统进行比较分析。     

水平管路清管过程流动参数变化规律模拟研究

混输管路清管技术的研究对混输管道的运行管理具有非常重要的意义。在分析清管器清管物理模型的基础上 ,建立清管器的特征参数计算模型、动态数学模型和数值计算方法 ,并进行数值模拟 ,计算出测压点压力随时间变化的数据 ,并把它们与试验数据进行比较 ,得到清管过程中压力的变化规律。通过数学模拟 ,可以计算清管过程中管道的压力分布状况 ,利用压力分布状况就可跟踪清管球在管道内的运行情况     

复杂形体目标激光散射特征测量系统的研制

复杂形体目标激光散射特征的测量系统中，利用反射式离轴光路满足了可见到远红外波段的测量需要，通过大孔径（250mm）物方远心接收光路实现了对实际远场的模拟测量，以光滑镀金球体作为标准器，可直接获得任意目标散射截面的绝对值。在0．6328、1．06和10．6μm三个波段针对标准器的实测结果表明，平均误差小于4．95％。     

Robust Redundancy Scheme for the Repair Process: Hierarchical Codes in the Bandwidth-Limited Systems

High performance computing can be well supported by the Grid or cloud computing systems. However, these systems have to overcome the failure risks, where data is stored in the “unreliable” storage nodes that can leave the system at any moment and the nodes’ network bandwidth is limited. In this case, the basic way to assure data reliability is to add redundancy using either replication or erasure codes. As compared to replication, erasure codes are more space efficient. Erasure codes break data into blocks, encode these blocks and distribute them into different storage nodes. When storage nodes permanently or temporarily abandon the system, new redundant blocks must be created to guarantee the data reliability, which is referred to as repair. Later when the churn nodes rejoin the system, the blocks stored in these nodes can reintegrate the data group to enhance the data reliability. For “classical” erasure codes, generating a new block requires to transmit a number of k blocks over the network, which brings lots of repair traffic, high computation complexity and high failure probability for the repair process. Then a near-optimal erasure code named Hierarchical Codes, has been proposed that can significantly reduce the repair traffic by reducing the number of nodes participating in the repair process, which is referred to as the repair degree d. To overcome the complexity of reintegration and provide an adaptive reliability for Hierarchical Codes, we refine two concepts called location and relocation, and then propose an integrated maintenance scheme for the repair process. Our experiments show that Hierarchical Code is the most robust redundancy scheme for the repair process as compared to other famous coding schemes.     

Study on pH‐sensitive and thermosensitive polymer networks containing polyacetal segments

A series of pH‐sensitive and thermosensitive polymer networks were first obtained by copolymerization of telechelic poly(1,3‐dioxolane) (PDXL) with acrylic acid (AA), acrylamide (AM), and N‐isopropylacrylamide (NIPAM), respectively. The copolymerization of PDXL diacrylate (PDXLDA) with AA, AM, or NIPAM is expected to lead to polymer networks in which homopolymeric segments of the monomer are connected by polyacetal segments. As a combination of these two parts, these polymer networks can have some interesting physical properties. For example, the copolymer networks of poly(AA‐b‐DXL) showed pH sensitivity, and both the copolymer networks of poly(AM‐b‐DXL) and poly(NIPAM‐b‐DXL) showed temperature sensitivity. Moreover, because of the low ceiling temperature of polyDXL, the networks containing polyacetal segments (PDXL) can degrade by treatment with a trace of appropriate cationic initiator. The polymer networks prepared were characterized by Fourier transform infrared, differential scanning calorimetry, and swelling data. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3002–3006, 2002; DOI 10.1002/app.2329     

基于APDL的ANSYS嵌入式配筋实现

以ANSYS为平台,应用APDL实现钢筋混凝土有限元模型中钢筋单元嵌入混凝土单元的功能.应用该方法可以在ANSYS中方便地建立复杂的钢筋混凝土分离式模型.利用Newton-Raphson方法求解等参数单元的坐标插值函数中被约束节点在自然坐标系下的坐标值,得到自然坐标系下节点对应形函数值,并将对应的形函数值作为约束方程中混凝土单元节点位移的分项因数,从而实现嵌入节点与被嵌入单元位移协调.计算结果与Marc的算例结果吻合良好,说明该方法合理.     

基于软件定义网络和移动边缘计算的车联网高效任务卸载方案

随着车联网(IoV)中车辆和智能应用数目的增加使计算密集型任务激增,传统架构难以满足用户需求。为解决车联网计算资源不足且分配不均匀、应用时延需求无法满足、任务能耗成本较高的问题,结合移动边缘计算(MEC)和软件定义网络(SDN),设计了一种从宏基站到MEC服务器到车辆的车联网架构中的高效任务卸载方案,并提出一种改进的低复杂度非支配排序遗传算法,优化任务卸载成本和MEC服务器的负载均衡率。实验仿真结果表明,相比于随机卸载,NO-MEC卸载,NO-I卸载,传统NSGA、NSGA-Ⅱ卸载,GA卸载,Q-learning卸载,DQN卸载方案,所提方案有着更低的卸载成本,更优的负载均衡率,得到近似最高的系统效用,能够给车联网中的车辆用户带来更优质的网络服务。