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排序方式: 共有2433条查询结果,搜索用时 15 毫秒
31.
Mu Lei Wang Yuan Zang Yong Araujo Stemler Pedro Malaquias 《Journal of Failure Analysis and Prevention》2017,17(2):321-329
This paper is a contribution to the prediction of edge fracture behavior using uncoupled ductile fracture models. A fully integrated simulation framework for the edge fracture prediction is proposed with the shear-induced pre-damage considered. User-defined material subroutines are coded with uncoupled ductile fracture models (Lou-Huh, Oh, Brozzo) incorporated, which are calibrated using the fracture strains of various loading paths. A series of 3D numerical simulations are performed and compared with the results of hole-expansion tests. The effects of pre-damage field and fracture models are analyzed and discussed.
相似文献32.
This paper presents an unsupervised structural damage pattern recognition approach based on the fuzzy clustering and the artificial immune pattern recognition (AIPR). The fuzzy clustering technique is used to initialize the pattern representative (memory cell) for each data pattern and cluster training data into a specified number of patterns. To improve the quality of memory cells, the artificial immune pattern recognition method based on immune learning mechanisms is employed to evolve memory cells. The presented hybrid immune model (combined with fuzzy clustering and the artificial immune pattern recognition) has been tested using a benchmark structure proposed by the IASC–ASCE (International Association for Structural Control–American Society of Civil Engineers) Structural Health Monitoring Task Group. The test results show the feasibility of using the hybrid AIPR (HAIPR) method for the unsupervised structural damage pattern recognition. 相似文献
33.
Yu Zhang Zang Li Trappe W. 《Information Forensics and Security, IEEE Transactions on》2008,3(2):259-272
Location information should be verifiable in order to support new computing and information services. In this paper, we adapt the classical challenge-response method for authentication to the task of verifying an entity's location. Our scheme utilizes a collection of transmitters, and adapts the power allocations across these transmitters to verify a user's claimed location. This strategy, which we call a power-modulated challenge response, is able to be used with existing. wireless sensor networks. First, we propose a direct method, where some transmitters are selected to send ldquochallengesrdquo that the claimant node should be able to witness based on its claimed location, and for which the claimant node must correctly respond to in order to prove its location. Second, we reverse the strategy by presenting an indirect method, where some transmitters send challenges that the claimant node should not be able to witness. Then, we present a signal-strength-based method, where the node responds with its received signal strength and thereby provides improved location verification. To evaluate our schemes, we examine different adversarial models for the claimant, and characterize the performance of our power-modulated challenge response schemes under these adversarial models. Further, we propose a new localization attack, where a set of nodes collaborates to pretend that there is a node at the claimed location. This collusion attack can do tremendous harm to localization and the performance of the aforementined methods under collusion attack are explained. Finally, we propose the use of a rotational directional power-modulated challenge response, where directional antennas are used to defend against collusion attacks. 相似文献
34.
35.
Though principle component analysis (PCA) and locality preserving projections (LPPs) are two of the most popular linear methods for face recognition, PCA can only see the Euclidean structure of the training set and LPP preserves the nonlinear submanifold structure hidden in the training set. In this paper, we propose the elastic preserving projections (EPPs) which by incorporating the merits of the local geometry and the global information of the training set. EPP outputs a sample subspace which simultaneously preserves the local geometrical structure and exploits the global information of the training set. Different from some other linear dimensionality reduction methods, EPP can be deemed as learning both the coordinates and the affinities between sample points. Furthermore, the effectiveness of our proposed algorithm is analyzed theoretically and confirmed by some experiments on several well-known face databases. The obtained results indicate that EPP significantly outperforms its other rival algorithms. 相似文献
36.
The dispersion of nanosilica that was modified and original in organic solvents could be judged directly by using methyl red
as the indicator, and the principle of color development was also discussed. A method has been developed for the determination
of the acidity of solid surfaces, which consists of titration of the solid suspended in benzene with n-butyl amine, using neutral red as the indicator. Basic indicator forms a red color on acidic solids, and the end-point of
the titration is the disappearance of the red color.
The text was submitted by the authors in English. 相似文献
37.
Silane coupling agent was used to introduce polymeric groups that was C=C onto the surface of nano-SiO2 particles by self-assembling technique. Then, in situ grafted polymerization was carried out between the functionalized particles
and butyl methacrylate monomers under the action of an initiating agent to accomplish the surface modification of nano-SiO2. The effect of different reaction conditions on grafting percentage was studied, and analyses of FTIR, TEM, and TG-DTA results
show that new organic chains were introduced onto the surface of nano-SiO2, and the dispersion stability of nano-SiO2 in THF was obviously improved.
The text was submitted by the authors in English. 相似文献
38.
基于QuickServer设计并实现了支持IPv4和IPv6协议的Ftp服务器。对IPv4环境中的应用程序向IPv6迁移进行了实质性的探索和研究。 相似文献
39.
40.
履带车辆电传动系统电气机械联合制动优化控制与仿真 总被引:1,自引:0,他引:1
根据电传动研究情况,提出了电传动电气机械联合制动优化控制目标;在这个目标下,完成了电气制动控制策略优化,进行了原车机械制动系统在联合制动中制动力的分配,通过试验和仿真说明它的合理性;最后给出联合制动的仿真结果,并进行了分析。 相似文献