Edge Fracture Prediction Using Uncoupled Ductile Fracture Models for DP780 Sheet

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.

     

含能共晶技术研究进展

含能共晶技术在分子水平上可实现具有不同性能的含能化合物(如高能分子与低感度分子)之间的非共价键作用,并赋予含能化合物新的性能。同时,含能共晶技术在不改变原有含能化合物分子结构的前提下,可提高其稳定性,降低其感度。目前,高能量低感度含能化合物已成为研究热点之一。着重介绍了含能共晶技术的国内外研究现状,并主要从基础研究、研究进展、发展动态分析与理论计算等几个方面进行总结,最后对含能共晶技术研究存在的问题进行了分析。     

含能共晶技术研究进展

含能共晶技术在分子水平上可实现具有不同性能的含能化合物(如高能分子与低感度分子)之间的非共价键作用,并赋予含能化合物新的性能.同时,含能共晶技术在不改变原有含能化合物分子结构的前提下,可提高其稳定性,降低其感度.目前,高能量低感度含能化合物已成为研究热点之一.着重介绍了含能共晶技术的国内外研究现状,并主要从基础研究、研究进展、发展动态分析与理论计算等几个方面进行总结,最后对含能共晶技术研究存在的问题进行了分析.     

Crystal structure of Cr4AlB4: A new MAB phase compound discovered in Cr-Al-B system

In this communication, the crystal structure of Cr_4AlB_4, a new MAB phase compound(where M is a transition metal, A is Al or Si, B is boron) discovered in Cr-Al-B system is reported. This new MAB phase was synthesized from a mixture of CrB and Al powders at 1000?C and its crystal structure was determined by a combination of X-ray diffraction, first-principles calculations and energy dispersive X-ray spectroscopy(EDS). Cr_4AlB_4 crystallizes in an orthorhombic structure with Immm space group. The lattice constants are a = 2.9343(6) ?, b = 18.8911(0) ?, c = 2.9733(7) ?, and the atomic positions are Cr1 at 4 g(0, 0.2936(5),0), Cr2 at 4 h(0.5, 0.5859(7), 0), Al at 2 b(0, 0.5, 0.5), B1 at 4 h(0, 0.3839(8), 0.5) and B2 at 4 g(0.5, 0.6646(2),0.5).     

改进的本体中概念相似度计算方法

随着本体的增多,本体异构是本体间互操作的主要障碍,阻碍了本体信息共享,解决本体异构最好的方法是本体映射。本体映射的关键是概念相似度的计算,但现今的计算模型考虑的影响因素比较单一。结合距离语义相似度和属性语义相似度,提出了一种综合语义相似度计算方法。实验证明,该方法可以提高计算结果的精确度。     

A hybrid immune model for unsupervised structural damage pattern recognition

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.     

一种基于子串识别的多模式串匹配算法

多模式串匹配算法是网络内容过滤系统的核心技术。巨大的存储空间开销是制约多模式匹配串算法应用的瓶颈之一。提出一种基于子串识别的多模式匹配算法—HashBOM,该算法利用位哈希表存储模式串的子串信息以大幅度减少存储空间,利用递归哈希函数计算字符串的哈希值以实现快速匹配。理论分析表明,该算法的空间复杂度为O(rm~2),优于基于子串识别的匹配算法BOM的空间复杂度O(mr|∑|log_2mr);该算法搜索匹配过程的平均时间复杂度为O(nlog|∑|)mr/m,与BOM算法相同(其中m为最短模式串的长度,r为模式串的个数,n为待匹配文本的长度,|∑|为字母表的大小)。在随机数据集和真实数据集上的实验表明,该算法的存储空间远远低于BOM算法,而匹配速度与BOM算法相当,非常适合在线实时匹配的应用环境。     

Invariant object recognition based on combination of sparse DBN and SOM with temporal trace rule

Multimedia Tools and Applications - This paper proposes a trace rule based self-organized map (SOM) model built upon a sparse 2-stage deep belief network (DBN). The combination of SOM and sparse...     

Evaluation of Localization Attacks on Power-Modulated Challenge–Response Systems

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.     

Pseudoelastic behavior in Y1−xPrxBa2Cu3Oy compounds

Tensile tests show that ferroelastic loops always occur at 100–150 K, 200–250 K and room temperature in the Y_1–xPr_xBa₂Cu₃O_y samples withx=0 and 0.1 for whichT _c is 92 K and 82.5 K respectively, and the shape memory effect is always observed in the compact sample near 130 K, just similar to that of thermal elastic martensitic alloys. The loss fraction (W/W) which is proportional to the area of ferroelastic loop as a function of temperature shows that there always exist static hysteresis (W/W) peaks at 130 K and 110 K which are attributed to the phaselike transition (PLT) characterized by the jump of lattice parameters. No ferroelastic loops and shape memory effect are observed in the range of 100 K to 150 K for the lowerT _c samples withx=0.3, 0.4 and 0.6.