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91.
92.
In this paper we analyze an elliptic partial differential equation involving variable exponent growth conditions coupled with a nonlinear boundary condition. We show the existence of infinitely many bounded weak solutions provided there is a suitable oscillatory behavior of the nonlinearity either at infinity or at zero. Our proofs rely on a method due to Saint Raymond. 相似文献
93.
In this paper, we present new pointcuts and primitives to Aspect-Oriented Programming (AOP) languages that are needed for systematic hardening of security concerns. The two proposed pointcuts allow to identify particular join points in a program's control-flow graph (CFG). The first one is the GAFlow, Closest Guaranteed Ancestor, which returns the closest ancestor join point to the pointcuts of interest that is on all their runtime paths. The second one is the GDFlow, Closest Guaranteed Descendant, which returns the closest child join point that can be reached by all paths starting from the pointcut of interest. The two proposed primitives are called ExportParameter and ImportParameter and are used to pass parameters between two pointcuts. They allow to analyze a program's call graph in order to determine how to change function signatures for passing the parameters associated with a given security hardening. We find these pointcuts and primitives to be necessary because they are needed to perform many security hardening practices and, to the best of our knowledge, none of the existing ones can provide their functionalities. Moreover, we show the viability and correctness of the proposed pointcuts and primitives by elaborating and implementing their algorithms and presenting the result of explanatory case studies. 相似文献
94.
95.
《Journal of Computer and System Sciences》2016,82(3):477-487
The exponent of a word is the quotient of its length over its smallest period. The exponent and the period of a word can be computed in time proportional to the word length. We design an algorithm to compute the maximal exponent of all factors of an overlap-free word. Our algorithm runs in linear-time on a fixed-size alphabet, while a naive solution of the question would run in cubic time. The solution for non-overlap-free words derives from algorithms to compute all maximal repetitions, also called runs, occurring in the word.We also show there is a linear number of occurrences of maximal-exponent factors in an overlap-free word. Their maximal number lies between 0.66n and 2.25n in a word of length n. The algorithm can additionally locate all of them in linear time. 相似文献
96.
基于新的超混沌系统的图像加密方案 总被引:7,自引:0,他引:7
提出了一个新的超混沌系统,分析了新系统的混沌吸引子相图、平衡点及其性质、工yapunov指数等非线性动力学特性,并用该超混沌系统对图像进行加密研究。给出了一种新的基于四维超混沌系统的图像加密算法。实验结果及安全性分析表明,该算法具有较强的抵御穷举攻击、统计攻击、已知明文攻击能力,因而具有较高的安全性。 相似文献
97.
一个双色有向图D是本原的,如果存在非负整数h和k,h+k>0,使得D的每对顶点(i,j)都存在从i到j的(h,k)-途径,称h+k的最小值为本原双色有向图D的指数.给出了一类含两个圈的特殊本原双色有向图指数的紧的上下界,并对一类特殊情况进行了极图刻划. 相似文献
98.
该文提出了一种基于Chen系统的新型三维指数混沌系统.重点分析了系统参数对整个混沌系统的影响,给出了混沌系统吸引子图,Lyapunov指数图,分叉图等.最后利用DSP实现了该混沌系统,并对由系统生成的数字序列做了NIST测试,测试结果表明序列性能良好. 相似文献
99.
LEE Jeung-Hoon JUNG Jae-Kwon LEE Kyung-Jun HAN Jae-Moon PARK Hyung-Gil SEO Jong-Soo 《水动力学研究与进展(B辑)》2012,24(5):658-667
Tip vortex cavitation noise of marine propeller became primary concerns to reduce hazardous environmental impacts from commercial ship or to keep the underwater surveillance of naval ships. The investigations of the tip vortex and its induced noise are normally conducted through the model test in a water cavitation tunnel. However the Reynolds number of model-test is much smaller than that of the full-scale, which subsequently results in the difference of tip vortex cavitation inception. Hence, the scaling law between model-and full-scales needs to be identified prior to the prediction and assessment of propeller noise in full scale. From previous researches, it is generally known that the incipient caivtation number of tip vortex can be represented as a power of the Reynolds number. However, the power exponent for scaling, which is the main focus of this research, has not been clearly studied yet. This paper deals with the estimation of scaling exponent based on tip vortex cavitation inception test in both full-and model-scale ships. Acoustical measurements as well as several kind of signal processing technique for an inception criterion suggest the scaling exponent as 0.30. The scaling value proposed in this study shows slight difference to the one of most recent research. Besides, extrapolation of model-ship noise measurement using the proposed one predicts the full-scale noise measurement with an acceptable discrepancy. 相似文献
100.
微博社区中用户行为特征及其机理研究 总被引:1,自引:0,他引:1
基于微博数据的实证分析表明,微博用户发布微博的数量及时间间隔均服从幂律分布。通过分析微博用户之间的社会网络关系与用户行为之间的联系,发现微博消息数量的分布幂指数与用户互动指数呈反向关系,且随着互动指数的升高,幂指数的下降趋缓。在排除用户之间的评论、转发行为的影响后,个体用户发微博的时间间隔分布幂指数与用户互动指数呈正相关关系。基于上述实证分析,引入用户间评论转发行为、用户间的社会网络关系作为微博用户行为的驱动因素,提出了一种基于社会关系的动力学模型,模型仿真结果与实际数据一致。 相似文献