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841.
We describe a batch RSA digital signature scheme in which a signer can sign messages for multiple recipients simultaneously.
The construction is quite efficient due to the batch signing method. This is useful to improve the performance of a high-loaded
signing server, for example a secure electronic transaction (SET) gateway. Theoretical calculations and experimental results
show that the proposed scheme can improve the performance of the signing server significantly.
Foundation item: the National Basic Research Program (973) of China (No. 2005CB321804) 相似文献
842.
Steel wire wound reinforced flexible pipe in this study mainly consists of multiple anisotropic steel wire wound reinforcement
layers and multiple isotropic rubber layers. Based on 3D anisotropic elastic theory, the analytic solutions of stresses and
elastic deformations of steel wire wound reinforced rubber flexible pipe under internal pressure are presented. As the adjacent
reinforcement layers with wound angle have different radii, the single reinforcement layer shows the effect of tensile-shear
coupling. Moreover, the static loading test results of steel wire wound reinforced rubber flexible pipe under internal pressure
are basically coincided with the calculated values by present method. 相似文献
843.
In this paper, we study an area localization problem in large scale underwater wireless sensor networks (UWSNs). The limited
bandwidth, the severely impaired channel and the cost of underwater equipment all make the underwater localization problem
very challenging. Exact localization is very difficult for UWSNs in deep underwater environment. We propose a range free method
based on mobile detachable elevator transceiver (DET) and 3D multi-power area localization scheme (3D-MALS) to address the
challenging problem. In the proposed scheme, the ideas of 2D multi-power area localization scheme (2D-ALS) and utilizing DET
are used to achieve the simplicity, location accuracy, scalability and low cost performances. The DET can rise and get down
to broadcast its position. And it is assumed that all the underwater nodes underwater have pressure sensors and know their
z coordinates. We evaluate the performances of 2D-ALS and our proposed 3D-MALS schemes under both ideal and non-ideal channel
propagation conditions, in terms of localization error and localization ratio. The simulation results show that our proposed
scheme is much more efficient than the 2D-ALS. 相似文献
844.
A computer-aided method to design a hybrid layout—tree-shape planar flowlines is presented. In newtype flowshop layout, the
common machines shared by several flowlines could be located together in functional sections. The approach combines traditional
cell formation techniques with sequence alignment algorithms. Firstly, a sequence analysis based cell formation procedure
is adopted; then the operation sequences for parts are aligned to maximize machines adjacency in hyperedge representations;
finally a tree-shape planar flowline will be obtained for each part family. With the help of a sample of operation sequences
obtained from industry, this algorithm is illustrated. 相似文献
845.
A novel algorithm to voxelize 3D mesh models with gray levels is presented in this paper. The key innovation of our method
is to decide the gray level of a voxel according to the total area of all surfaces contained by it. During the preprocessing
stage, a set of voxels in the extended bounding box of each triangle is established. Then we travel each triangle and compute
the areas between it and its set of voxels one by one. Finally, each voxel is arranged a discrete gray level from 0 to 255.
Experiments show that our algorithm gets a comparatively perfect result compared with the prevenient ones and approaches the
original models in a more accurate way. 相似文献
846.
Mobile ad hoc networks are often deployed in environments where the nodes of the networks are unattended and have little or
no physical protection against tampering. The nodes of mobile ad hoc networks are thus susceptible to compromise. The networks
are particularly vulnerable to denial of service (DoS) attacks launched through compromised nodes or intruders. In this paper,
we investigated the effects of flooding attacks in network simulation 2 (NS-2) and measured the packet delivery ratio and
packet delay under different flooding frequencies and different numbers of attack nodes. Simulation results show that with
the increase the flooding frequencies and the numbers of attack nodes, network performance drops. But when the frequency of
flooding attacks is greater than a value, the performance decrease gets smooth. Meanwhile the packet delay firstly increases
and then declines to a value of stability at the end. 相似文献
847.
结合某车型制动踏板支架的逆向设计,介绍了基于曲面特征的建模策略和方法,详细分析了扫掠面和旋转面的重构方法,以及逆向设计建模过程中特征曲线提取的方法与技巧. 相似文献
848.
基于直接横摆力矩控制方法,设计了一种前馈一反馈补偿控制的车辆稳定性控制器.其中控制器以4WS为期望的车辆模型,通过前馈补偿控制可使车辆的质心侧偏角趋于理想值,而反馈补偿控制可使车辆模型在较好地跟踪理想模型的基础上,有效抵抗外界干扰.通过前轮角阶跃输入与正弦输入仿真,就控制效果的稳定性与对前轮转角的跟随特性两方面而言,所设计的控制系统能较好地控制车辆的操纵稳定性. 相似文献
849.
浙江是一个多山地区,公路修建必然带来大量的人工边坡,而边坡潜在滑动可能性对高速公路安全运营会产生威胁。本文对龙丽高速公路裕溪滑坡的整体稳定性的系统监测进行总结分析,通过对监测结果的分析可知,边坡虽产生一定的位移,但其基本处于稳定状态。 相似文献
850.
周衍领 《国防交通工程与技术》2009,7(6):17-19,30
针对新建厦深铁路榕江特大桥主桥连续钢桁梁柔性拱的结构特点,结合设备、工期和气候环境等影响因素,对连续钢桁梁的三种施工方案:利用临时塔架及拉索对称悬拼方案、采用临时支墩配合对称悬拼方案和采用临时支墩不对称悬拼方案进行了比选,最终确定采用临时支墩配合对称悬拼的连续钢桁梁柔性拱施工方案,具有施工设备投入少、风险低、工期短等优势,为编制施工组织设计提供了技术支持。 相似文献