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61.
车联网在生活中扮演着越来越重要的角色,它可以有效地防止交通拥堵从而减少交通事故。然而,在车联网中总是有非法车辆试图接入车联网并发布虚假消息。此外,现有方案多数存在计算效率低下的问题。针对上述存在的问题进行了研究,提出了一种车联网中基于雾计算和多TA的条件隐私保护认证方案。在保护车辆用户身份的条件下实现了车辆、雾节点、TA三者之间的身份认证,且在车辆追踪阶段可以还原车辆用户的真实身份,从而实现条件隐私保护。雾计算的使用降低了方案的计算和通信开销,同时多TA模型的使用也解决了单TA单点故障的问题。安全性证明和性能分析的结果表明该方案是安全且高效的。最后对当前方案进行了总结以及对未来研究作出了展望。 相似文献
62.
Polypropylene (PP)/layered silicate nanocomposites were prepared via simple melt mixing of three components, PP, layered silicates modified with octadecylamine (C18-MMT) and antioxidant, to investigate the role of antioxidant. TEM and X-ray scattering results confirmed the intercalated state of silicates in PP/layered silicate nanocomposites with antioxidant. In rheological and mechanical study, the nanocomposites with antioxidant showed higher properties than those of the unfilled PP. The nanocomposite with 5 wt% C18-MMT and 0.5 phr antioxidant exhibited about 1.4 times higher tensile modulus and 1.3 times higher storage modulus than the unfilled PP. However, PP/C18-MMT without antioxidant showed lower rheological values owing to the thermal decomposition of PP and the poor compatibility between PP and C18-MMT. It could be concluded that antioxidants played an important role in enhancing the compatibility between PP and C18-MMT. According to the real time X-ray diffraction, the nanocomposite showed the weak ordering of PP crystals than the unfilled PP in the load-extension plateau region of elongation. 相似文献
63.
K.M Shaju 《Electrochimica acta》2003,48(18):2691-2703
Li ion kinetics in the O2-phase layered manganese oxides, Li2/3(Co0.15Mn0.85)O2 (O2(Li)) and Li(2/3)+x(Co0.15Mn0.85)O2 (x=1/3 (O2(Li+x))), has been studied by the electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT) at room temperature and the results were correlated with the observed cathodic behaviour. Both compounds show a reversible capacity of ∼180 mA h/g at low current density (∼5 mA/g). EIS studies as a function of cycle number show an increased contribution of resistance associated with surface film formation and bulk contribution which is in agreement with the increased capacity fading observed in O2(Li+x) after 10-15 cycles. The Li ion diffusion coefficient (DLi) vs voltage plots show minima during the first charge cycle coinciding with the irreversible plateau of the voltage vs capacity profiles reflecting the irreversible phase change in both the compounds. The values of DLi (GITT method) observed for the second and subsequent cycles (≤6) in the full voltage range (3.0-4.4 V) are 2×10−11-10×10−11 cm2/s for O2(Li+x) and 0.5×10−10-3.0×10−10 cm2/s for O2(Li). Variation of DLi as a function of cycle number (up to 35) indicates that, in addition to the interface kinetics, changes in the DLi values with cycling also contribute to the capacity fading of the compounds, especially in O2(Li+x). 相似文献
64.
65.
Ki Soo ParkMyung Hun Cho Sang Ho ParkKee Suk Nahm Yang Kook SunYun Sung Lee Masaki Yoshio 《Electrochimica acta》2002,47(18):2937-2942
Layered Li0.7[M1/6Mn5/6]O2 (M=Li, Ni) was synthesized using a sol-gel method. P2-Na0.7[M1/6Mn5/6]O2 precursor was first synthesized by a sol-gel method, and then O2-Li0.7[M1/6Mn5/6]O2 was prepared by an ion exchange of Li for Na in P2-Na0.7[M1/6Mn5/6]O2 precursor. From charge/discharge curves, it was seen that Li0.7[Li1/6Mn5/6]O2 has two plateaus similar to those observed from a spinel structure, but Li0.7[Ni1/6Mn5/6]O2 holds a single plateau as observed from a typical layered structure. It was considered that Li0.7[Li1/6Mn5/6]O2 undergoes a phase transformation from layered to spinel structure during the charge/discharge cycle, but Li0.7[Ni1/6Mn5/6]O2 maintains O2-layered structure after the cycles. Li0.7[Ni1/6Mn5/6]O2 was higher in discharge capacity and retention rate than Li0.7[Li1/6Mn5/6]O2. 相似文献
66.
67.
介绍了LTE系统在北京地铁范围内进行系统覆盖时,多系统间干扰问题的分析及计算.本文通过北京地铁这样的特殊场景,结合LTE系统的特点,辅以理论分析及现场测试,分析了在多系统(地铁信号系统、其他运营商等)环境下,在大客流、高速度及系统复杂的地下轨道空间内建设并使用LTE系统的方法. 相似文献
68.
以客户为中心是众多企业战略规划的重点,如何在信息技术飞速发展中,根据客户的特征、行为和偏好来获取新客户、促进企业的发展,企业客户信息系统的信息化建设已成为重中之重。采用J2EE设计了一个支持多层架构,并具有良好的可用性、伸缩性、扩展性、安全性的系统。系统可以实现对企业客户信息的数据管理、数据统计、数据维护等功能,提高了企业办公效率,完善了客户服务体系。 相似文献
69.
《Journal of Visual Languages and Computing》2014,25(2):89-106
Complex software systems are often modeled using data flow diagrams, in which nodes are connected to each other through dedicated connection points called ports. The influence a layout algorithm has on the placement of ports is determined by port constraints defined on the corresponding node.In this paper we present approaches for integrating port constraints into the layer-based approach to graph drawing pioneered by Sugiyama et al. We show how our layout algorithm, called KLay Layered, progresses from relaxed to more restricted port constraint levels as it executes, and how established algorithms for crossing minimization and edge routing can be extended to support port constraints. Compared to the previous layout algorithms supporting ports, our algorithm produces fewer edge crossings and bends and yields pleasing results.We also explain and evaluate how layout algorithms can be kept simple by using the concept of intermediate processors to structure them in a modular way. A case study integrating our layout algorithm into UC Berkeley's Ptolemy tool illustrates how KLay Layered can be integrated into Java-based applications. 相似文献
70.
This paper studies the containment control problem for multi‐agent systems consisting of multiple leaders and followers connected as a network. The objective is to design control protocols so that the leaders will converge to a certain desired formation while the followers converge to the convex hull of the leaders. A novel protocol is proposed by exploiting the control input information of neighbors. Both continuous‐time and discrete‐time systems are considered. For continuous‐time systems, it is proved that the protocol is robust to any constant delays of the neighbors' control inputs. For discrete‐time systems, a sufficient condition on the feedback gain for the containment control is given in terms of the time delay and graph information. Some numerical examples are given to demonstrate the results. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献