LF2铝合金搅拌摩擦焊接头的疲劳特性

对LF2铝合金搅拌摩擦焊接头的疲劳特性进行了研究，建立了焊接头的S-N曲线。疲劳试验结果表明，搅拌摩擦焊接头表现出良好的疲劳性能，疲劳寿命N=10^6次的疲劳强度值约为59～65MPa。搅拌摩擦焊接头具有细小的等轴晶粒和狭窄的热影响区，阻碍了滑移带的形成和裂纹的扩展，从而提高了接头的疲劳性能。疲劳断口分析显示，随着驻留滑移带的扩展逐渐萌生裂纹，在交变应力作用下最终导致失效。     

消失模铸造用EPMMA模样的收缩特性

以可发性聚甲基丙烯酸甲酯(EPMMA)模样为研究对象，系统研究了珠粒粒径、预发泡时间、预发泡珠粒熟化时间、成形蒸气压力、模样的贮存温度及放置时间对模样收缩率的影响。研究结果表明，EPMMA模样在脱模时大约有0．1％左右的收缩，此后随着模样放置时间的延长，模样收缩逐渐增大，并在一定的时间(室温贮存约30天，50℃贮存约15天)后收缩稳定在0.5％～0．6％。而在所研究的工艺因素中，以成形蒸气压力对模样收缩的影响最大，其次是预发泡珠粒熟化时间，而珠粒粒径和预发泡时间的影响则相对较小。     

The CARE platform for the analysis of behavior model inference techniques

ContextFinite State Machine (FSM) inference from execution traces has received a lot of attention over the past few years. Various approaches have been explored, each holding different properties for the resulting models, but the lack of standard benchmarks limits the ability of comparing the proposed techniques. Evaluation is usually performed on a few case studies, which is useful for assessing the feasibility of the algorithm on particular cases, but fails to demonstrate effectiveness in a broad context. Consequently, understanding the strengths and weaknesses of inference techniques remains a challenging task.ObjectiveThis paper proposes CARE, a general, approach-independent, platform for the intensive evaluation of FSM inference techniques.MethodGrounded in a program specification scheme that provides a good control on the expected program structures, it allows the production of large benchmarks with well identified properties.ResultsThe CARE platform demonstrates the following features: (1) providing a benchmarking mechanism for FSM inference techniques, (2) allowing analysis of existing techniques w.r.t. a class of programs and/or behaviors, and (3) helping users in choosing the best suited approach for their objective. Moreover, our extensive experiments on different FSM inference techniques highlight that they do not behave in the same manner on every class of program. Characterizing different classes of programs thus helps understanding the strengths and weaknesses of the studied techniques.ConclusionExperiments reported in this paper show examples of use cases that demonstrate the ability of the platform to generate large and diverse sets of programs, which allows to carry out meaningful inference techniques analysis. The analysis strategies the CARE platform offers open new opportunities for program behavior learning, particularly in conjunction with model checking techniques. The CARE platform is available at http://care.lip6.fr.     

Evaluating the Wisdom of Strangers: The Perceived Credibility of Online Consumer Reviews on Yelp

This study examined the effects of review valence, the reviewer profile, and the receiver's familiarity with the platform (user/nonuser) on the perceived credibility of a review on Yelp.com and on the receiver's attitude toward the reviewed object. The results demonstrated a difference in cue‐taking between users and nonusers. For users, there was an interaction effect of 2 profile cues (number of friends and number of reviews) on competence. Users interpreted the cues in combination, whereas non‐users were not influenced by them. The friends × reviews × platform familiarity interaction indirectly affected attitude through competence. Further, review valence was positively associated with perceived credibility and attitude. The findings support and extend the social information processing theory and cue combination literature.     

基于行为检测的非法VOIP探测研究

VOIP以其高效、快捷、节约通信费用的特性,被越来越广的应用到人们生产、生活等方面。受利益等因素的驱动,越来越多的非法VOIP隐藏在广袤的互联网中。这些非法VOIP的设置者不但经营不合法,往往还会利用VOIP落地网关透传性等漏洞,进行敲诈、诈骗等犯罪活动,危害人民群众财产安全。研究现行法律法规及VOIP的技术原理,找出非法VOIP在互联网中的行为特点,针对这些特点建立有效检测模型,最终认定非法VOIP网关是打击非法设立VOIP的核心基础。     

构件行为协议实时性扩展及相容性验证

对复杂实时构件系统行为进行形式化描述和相容性验证,可以有效提高系统的正确性、可靠性。分析了学术界和工业界的主流构件模型及常见时间行为的形式化描述方法,对构件行为协议BP(Behavior Protocol)进行了扩展,提出了时间行为协议TbP(Timed Behavior Protocol),分析了构件组合中常见的相容性错误类型,给出了基于时间行为协议的构件组合相容性验证算法。TBP应用简洁、方便、易于验证。结合具体例子给出了应用示例。     

浅谈高校校园网络安全防范策略

随着高校网络信息化的不断发展,网络安全问题开始日益突出,如何建立一套安全可行的校园网络安全系统,是所有高校校园网络管理者所需要解决的问题。     

基于三阶帧差的运动特征选取方案

为解决行为识别中运动特征提取的问题,该文提出了一种基于三阶帧差的运动特征提取方案,用于提取运动特征中的变化大小、运动变化的一致性、运动方向的一致性等。实验证明,新方法速度快,准确度高。     

A novel three-tiered visualization approach for firewall rule validation

Firewall is one of the most critical elements of the current Internet, which can protect the entire network against attacks and threats. While configuring the firewalls, rule configuration has to conform to, or say be consistent with, the demands of the network security policies such that the network security would not be flawed. For the security consistency, firewall rule editing, ordering, and distribution must be done very carefully on each of the cooperative firewalls, especially in a large-scale and multifirewall-equipped network. Nevertheless, a network operator is prone to incorrectly configure the firewalls because there are typically thousands or hundreds of filtering/admission rules (i.e., rules in the Access Control List file, or ACL for short), which could be set up in a firewall; not mentioning these rules among firewalls affect mutually and can make the matter worse. Under this situation, the network operator would hardly know his/her misconfiguration until the network functions beyond the expectation. For this reason, our work is to build a visualized validation system for facilitating the check of security consistency between the rule configuration of firewalls and the demands of network security policies. To do so, the developed validation system utilizes a three-tiered visualization hierarchy along with different compound viewpoints to provide users with a complete picture of firewalls and relationships among them for error debugging and anomaly removal. In addition, in this paper, we also enumerate the source of security inconsistency while setting ACLs and make use of it as a basis of the design of our visualization model. Currently, part of the firewall configuration of our campus network has been used as our system's input to demonstrate our system's implementation.