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141.
E.J. Vanderperre 《International journal of systems science》2014,45(9):1970-1977
We analyse the survival time of a repairable duplex system characterised by cold standby and by a pre-emptive priority rule. We allow general probability distributions for failure and repair. Moreover, an important realistic feature of the system is the general assumption that the non-priority unit has a memory. This combination of features has not been analysed in the previous literature. Our (new) methodology is based on a concatenation of a Cauchy-type integral representation of the modified Heaviside unit-step function and a two-sided stochastic inequality. Finally, we introduce a security interval related to a security level and a suitable risk-criterion based on the survival function of the system. As a practical application, we analyse some particular cases of the survival function jointly with the security interval corresponding to a security level of 90. 相似文献
142.
Julius Parulek Daniel Jönsson Timo Ropinski Stefan Bruckner Anders Ynnerman Ivan Viola 《Computer Graphics Forum》2014,33(6):276-287
Molecular visualization is often challenged with rendering of large molecular structures in real time. We introduce a novel approach that enables us to show even large protein complexes. Our method is based on the level‐of‐detail concept, where we exploit three different abstractions combined in one visualization. Firstly, molecular surface abstraction exploits three different surfaces, solvent‐excluded surface (SES), Gaussian kernels and van der Waals spheres, combined as one surface by linear interpolation. Secondly, we introduce three shading abstraction levels and a method for creating seamless transitions between these representations. The SES representation with full shading and added contours stands in focus while on the other side a sphere representation of a cluster of atoms with constant shading and without contours provide the context. Thirdly, we propose a hierarchical abstraction based on a set of clusters formed on molecular atoms. All three abstraction models are driven by one importance function classifying the scene into the near‐, mid‐ and far‐field. Moreover, we introduce a methodology to render the entire molecule directly using the A‐buffer technique, which further improves the performance. The rendering performance is evaluated on series of molecules of varying atom counts. 相似文献
143.
针对传统方法刻画粗糙床面总体特征存在缺陷的问题,将分形几何理论引入非均匀卵砾石粗糙床面特征研究,以卵砾石床面激光扫描试验资料为基础,探讨了分形尺度区宽度与中值粒径d50的关系,分析了覆盖基准面对分形维数的影响,研究了床面整体与局部分形维数的特征与联系,获得了分形维数随床面颗粒组成及高程统计参数的变化规律。结果表明:分形尺度区宽度与床面颗粒中值粒径d50有关,上临界尺度可取为1.5d50;分形维数与覆盖基准面位置有关,覆盖基准面距平均床面的距离越大,分形维数越大且逐渐失真,为有效量化和区分床面粗糙特征,覆盖基准面宜取平均床面;粗糙床面分形维数具有良好的稳定性,局部分形维数变异性很小,并与整体分形维数接近;粗糙床面的分形维数与颗粒大小、级配组成及床面高程统计参数有关,中值粒径越大,颗粒组成越均匀,床面高程极差、标准差、偏度(绝对值)和峰度越大,分形维数越小。 相似文献
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146.
In large antenna arrays, the possibility of occurrence of faults in some of the radiating elements cannot be precluded at all times. In such situations, the radiation pattern of the array gets distorted, mostly with an increase in sidelobe level and decrease in gain. Although it is not possible to restore the pattern fully by rearranging the excitations of the functioning elements, compensation methods have been reported in the literature for restoring one performance parameter of the array and making a trade‐off on some other parameter. In this article, we have made a study on the tolerance level of this compensation process. One part of the study deals with the thinning in the failed array, that is, to find a limit on the minimum number of functioning elements of the array that can restore the digital beamforming of the failed array. The second part of study deals with finding the maximum number of element failures that can be compensated. The study was carried out by optimizing the amplitude excitations of the failed array. Instead of classical optimization techniques, particle swarm optimization was used for the compensation process. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:635–645, 2014. 相似文献
147.
The novel distributed mobility management trend is a promising direction to cope with the increasing mobile data traffic and flatten network architectures. Most of the novel mobility approaches distribute the mobility anchors through the access level, as opposed to the centralized mobility anchoring model. Other recent approaches argue that mobility anchors closer to the content servers may be the solution to optimize the mobility performance. However, none of the mobility anchoring models is ideal for all scenarios, since it depends on the user, the session and the network. Hence, we propose an IP mobility approach driven by the context of the user, sessions and the network, where the mobility anchors for IP address allocation and for routing/forwarding are distributed through the network nodes, while the mobility context is managed by the mobile devices. Although each session is properly anchored in the establishment phase, the routing/forwarding is adapted over time, according to the user, the session and the network context: the proposed approach is able to signal different mobility anchors to optimize the routing path to new and ongoing sessions of the user. The outcome of the evaluation shows that the proposed approach overall reduces the data cost, the data delay, the tunneled packets and the tunnel length, when compared with other anchoring models. 相似文献
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149.
为满足工程装备保障评估的要求和实现工程装备保障更为细致的仿真分析,提出了利用作战实验理论对工程装备保障评估方法研究的建设构想.在描述工程装备保障评估分析一般过程的基础上,从工程装备实体、保障要求等角度出发构建工程装备保障评估分析仿真模型,实现了对象间的交互作用、关系和消息传递,反映了“保障”作战任务、实体、功能、交互、活动等内在逻辑.用面向服务的高层体系结构(HLA)方法为工程装备保障评估分析仿真系统提供集成方法,为进一步仿真系统的论证、设计、开发提供了坚实基础. 相似文献
150.
智能手机上的恶意软件数量呈现爆炸式增长,目前迫切需要一个安全分析与检测方法.一个有效的检测与分析方法需要解决的最大问题就是如何从应用程序和恶意软件的汪洋大海中识别重新包装的应用程序.论文提出了基于三级签名的恶意软件分析方法MSAnalytics,根据API调用序列,提取在操作码级的恶意软件特征,生成应用程序三级签名.实验证明,MSAnalytics对重新包装恶意软件具有良好的分析能力. 相似文献