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Metal magnetic memory field characterization at early fatigue damage based on modified Jiles-Atherton model 被引量:5
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作者 徐明秀 徐敏强 +1 位作者 李建伟 邢海燕 《Journal of Central South University》 SCIE EI CAS 2012年第6期1488-1496,共9页
In order to propel the development of metal magnetic memory (MMM) technique in fatigue damage detection, the Jiles-Atherton model (J-A model) was modified to describe MMM mechanism in elastic stress stage. A serie... In order to propel the development of metal magnetic memory (MMM) technique in fatigue damage detection, the Jiles-Atherton model (J-A model) was modified to describe MMM mechanism in elastic stress stage. A series of rotating bending fatigue experiments were conducted to study the stress-magnetization relationship and verify the correctness of modified J-A model. In MMM detection, the magnetization of material irreversibly approaches to the local equilibrium state Mo instead of global equilibrium state M^n under cyclic stress, and the M0-a curves are loops around the Mar,-a curve. The modified J-A model is constructed by replacing M~ in J-A model with M0, and it can describe the magnetomechanical effect well at low external magnetic field. In the rotating bending fatigue experiments, the MMM field distribution in normal direction around cylinder specimen is similar to the stress distribution, and the calculation result of model coincides with experiment result after some necessary modifications. The MMM field variation with time at a certain point in fatigue process is divided into three stages with the variation of stable stress-stain hysteresis loop, and the calculation results of model can explain not only the three stages of MMM field changes, but also the different change laws when the applied magnetic field and initial magnetic field are different. The MMM field distribution in normal direction along specimen axis reflects stress concentration effect at artificial defect, and the magnetic signal fluctuates around the defect at late fatigue stage. The calculation results coincide with the initial MMM principle and can explain signal fluctuates around the defect. The modified J-A model can explain experiment results well, and it is fit for MMM field characterization. 展开更多
关键词 metal magnetic memory Jiles-Atherton model rotating bending fatigue magnetomechanical effect local equilibriumstate
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认知无线电网络中动态频谱分配策略的收费方案 被引量:3
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作者 金顺福 史国英 《燕山大学学报》 CAS 2014年第4期327-331,共5页
针对认知无线电网络中的动态频谱分配策略,考虑次级网络的响应性能,令中断传输的次级用户数据包立即离开系统。通过构造个人收益函数,基于可观察排队情形,给出均衡状态下系统中次级用户数据包的数量阈值,并建立一个带有传输中断的有限... 针对认知无线电网络中的动态频谱分配策略,考虑次级网络的响应性能,令中断传输的次级用户数据包立即离开系统。通过构造个人收益函数,基于可观察排队情形,给出均衡状态下系统中次级用户数据包的数量阈值,并建立一个带有传输中断的有限容量排队模型。基于Poisson过程,建立转移率矩阵,导出次级用户数据包的平均响应时间,系统吞吐量和频谱切换率等性能指标。为了实现动态频谱分配的社会最优,面向次级用户提出频谱接入的收费方案,并给出该收费方案的数值结果。 展开更多
关键词 认知无线电网络 动态频谱分配 传输中断 均衡状态 收费方案
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