软件定义网络中的DDoS安全

随着现代化信息技术的广泛应用,近年来,我国信息环境呈现了明显的复杂化演变趋势.基于网络信息安全,文章主要介绍了软件定义网络中的DDoS安全保证价值,并简要概述了软件定义网络中的DDoS攻击检测路径,探究基于SDSNM逻辑架构的防御体系、基于OpenFlow攻击缓解方法、基于强化学习的攻击防御系统和基于DPDK的攻击防御...     

Impact Dynamics of Supercavitating Projectile with Fluid/Structure Interaction

As supercavitating projectiles move at high speed, the periodic impacts ("tail-slap") on the interior surface of the cavity generally occur due to disturbances. The interactions between the projectile and the water/cavity interface are the sources of structural vibrations, which affect the guidance of the vehicle and undermine the structural reliability. The Fluid/Structure Interaction calculation procedure of the tail-slaps of supercavitating projectile is established, and the dynamic behaviours of the projectile operating in tail-slap conditions with and without considering Fluid/Structure Interaction are obtained and compared. The responses of the projectile riding a reducing cavity are studied, and the effect of Fluid/Structure Interaction is also analyzed. The results show that the angular velocity of projectile increases as the body slowing down, and the amplitude of the elastic displacement response decreases at the beginning and increases when the cavity size is close to the diameter of the tail of projectile. The effect of Fluid/Structure Interaction reduces the amplitudes and frequencies of the impact loads and the vibration responses of the body, and when the speed is higher, the effect is more apparent.     

新时期体育教学理念探索

新时期下的体育教学,在继续坚持教师的主导作用与学生的主动性相结合的教学原则基础上,还要更新教学思想和教学模式,适时采用合理的教学手段,有效培养学生的健康心理。与运动技能,以实现体育素质教育目标。     

一种基于对称集的平面图形匹配新方法

定义了一种新的形状描述子和一种矩阵内积.该描述子是二值对角对称图表,此图表具有图形上成对点的全局对称特性.在定义了矩阵的内积基础上,计算了两图形的匹配值.此定义方法缩短了匹配值的计算时间,通过几种类别的图形测试了这种描述子的描述能力.     

曲面造型的几何体素构造法

在ＣＡＤ，ＣＡＭ系统中，怎样更好地构造出有效的物体几何模型是系统的关键问题．现代几何造型技术的引入使其迎刃而解．本文通过对几何造型技术的研究，采用几何体素构造法对某些复合曲面进行了构造，并运用所开发的ＧＭＳ曲面造型系统进行了锻模型腔中圆弧、圆环过渡面的造型设计．     

新型单槽磷酸反应器（RTCB）的开发研究

本文旨在开发一种新型磷酸反应器──具有类似太极图曲线形隔板的单槽双区四桨反应器（ＲＴＣＢ反应器）。首先以自来水和磷石膏为搅拌介质进行冷模实验，冷模实验结果表明，ＲＴＣＢ反应器具有功耗低、悬浮、混合效果好、停留时间分布合理等优点。然后，采用同样的二水物流程工艺条件，选取道尔槽作参照物进行热模实验，热模实验结果表明，相同条件下与道尔槽相比，ＲＴＣＢ槽具有省功、磷石膏结晶环境优越、磷石膏洗涤率稍高等优点，但磷矿萃取率稍低，可望用于湿法磷酸的工业化生产。本文的研究工作将为该反应器的进一步开发应用提供依据。     

卧式下肢康复机器人主动柔顺控制实验研究

为保证下肢运动功能障碍患者在康复训练中的安全性和舒适性,利用力反馈信息采用阻抗控制原理设计了康复机器人系统的控制器,通过调整末端位置与力之间的关系使机器人具有一定的柔顺性.建立了系统的控制模型,并在dSPACE平台上进行了实验研究.结果表明,通过调节控制器中的阻抗参数,可以使机器人获得不同的刚度特性和阻尼特性,同时分析...     

The theory of multiple peeling

In this paper we derive the theory of multiple peeling, extending the pioneering energy-based single peeling theory of Kendall, including large deformations and pre-stretching. We can thus treat a complex system of films, adhering over a substrate and having a common hinge where the pulling force is applied. Two case studies are investigated: the asymmetric V-shape double peeling and the symmetric cone-shape configuration with N peeling tapes, both requiring the solution of six nonlinear coupled equations (instead of the one needed in the simpler single peeling problem). Remarkable implications emerge: (1) for moderate deformations, the critical strain of a tape is identical to that of the single peeling; (2) an optimal peeling angle, at which adhesion is maximal, is discovered; (3) an additional optimization, even for hierarchical structures, is introduced by imposing the delamination force equal to the intrinsic fracture of the tape. Also, the length of the peeling process zone is calculated, suggesting different optimal values for flaw-tolerant peeling at different angles. Applications to gecko adhesion, for which the flaw-tolerant peeling is demonstrated, and spider silk anchors, that we are going to discuss in details in subsequent papers, are envisioned (including a new pre-stretching mechanism for adhesion control) and suggested by the evidence of a smart mechanism capable of maximizing adhesion simply by increasing the applied tension.     

Multifunctional picoliter droplet manipulation platform and its application in single cell analysis

We developed an automated and multifunctional microfluidic platform based on DropLab to perform flexible generation and complex manipulations of picoliter-scale droplets. Multiple manipulations including precise droplet generation, sequential reagent merging, and multistep solid-phase extraction for picoliter-scale droplets could be achieved in the present platform. The system precision in generating picoliter-scale droplets was significantly improved by minimizing the thermo-induced fluctuation of flow rate. A novel droplet fusion technique based on the difference of droplet interfacial tensions was developed without the need of special microchannel networks or external devices. It enabled sequential addition of reagents to droplets on demand for multistep reactions. We also developed an effective picoliter-scale droplet splitting technique with magnetic actuation. The difficulty in phase separation of magnetic beads from picoliter-scale droplets due to the high interfacial tension was overcome using ferromagnetic particles to carry the magnetic beads to pass through the phase interface. With this technique, multistep solid-phase extraction was achieved among picoliter-scale droplets. The present platform had the ability to perform complex multistep manipulations to picoliter-scale droplets, which is particularly required for single cell analysis. Its utility and potentials in single cell analysis were preliminarily demonstrated in achieving high-efficiency single-cell encapsulation, enzyme activity assay at the single cell level, and especially, single cell DNA purification based on solid-phase extraction.     

Enhancement of gas sensing properties of CdS nanowire/ZnO nanosphere composite materials at room temperature by visible-light activation

CdS nanowire/ZnO nanosphere materials (CdS/ZnO) with hierarchical structure were synthesized by a three-step solvothermal process. XRD, FESEM and TEM analysis confirmed the growth of ZnO nanospheres on the surface of CdS nanowires (NWs). The transient photovoltage (TPV) measurements revealed that the interface between CdS and ZnO can inhibit the recombination of photogenerated excess carriers and prolong the lifetime of excess carriers in CdS/ZnO materials. Moreover, the CdS/ZnO materials exhibit a dramatic improvement in optoelectronic performance and visible-light-irradiation gas sensing activity, which gave 1 order of magnitude larger than that of CdS NWs in response to formaldehyde. The enhancement of sensing properties is attributed to the interfacial transport of excess carriers.