变形约束时效NiTi形状记忆合金弹簧的双程记忆效应

利用变形约束时效的方法制作了双程记忆弹簧,采用DSC和温度-位移记录仪表征了弹簧的相变行为和双程记忆效应。DSC和双程记忆动力学曲线均表明弹簧在升温过程的形状变化由马氏体逆相变M/R→A控制,而冷却过程受A→R→M两阶段相变控制,并且R相变对双程记忆应变量的贡献比马氏体相变的贡献大。与马氏体相变相比,R相变诱发的双程记忆效应具有较窄的动作滞后温度以及很高的记忆稳定性,这与变形约束时效时所获得的一定取向的Ti3Ni4相共格内应力场有关。结果表明:变形约束时效是获得双程记忆弹簧的良好途径,制作方法相对简单,获得的双程记忆应变量大,且稳定性高,尺寸制作具有很强的可设计性以及动作温度的可控性。     

疲劳损伤磁性无损评估技术研究现状及发展前景

磁性无损检测技术是评估铁磁材料疲劳损伤以及重要结构件可靠性的重要检测手段。针对铁磁材料的疲劳损伤,介绍了几种典型的磁性无损检测技术,如磁巴克豪森噪声(MBN)、磁声发射(MAE)、漏磁(MFL)和金属磁记忆(MMM)等,对其产生机理及应用特点进行了概述;对几种磁性检测技术在疲劳损伤评估领域的研究现状以及取得的主要研究成果进行了综述;最后指出几种技术尚存的问题和进一步的研究方向,并对其发展前景进行预测。     

聚合物基形状记忆合金复合材料研究进展

本文对聚合物基形状记忆合金复合材料的研究及应用进展进行了综述。着重介绍了该复合材料在结构设计、制备工艺技术以及应用等方面的研究成果以及发展概况,并对其发展前景进行了展望。     

Self‐Powered Trace Memorization by Conjunction of Contact‐Electrification and Ferroelectricity

Triboelectric nanogenerator (TENG) is a newly invented technology that can effectively harvest ambient mechanical energy from various motions with promising applications in portable electronics, self‐powered sensor networks, etc. Here, by coupling TENG and a thin film of ferroelectric polymer, a new application is designed for TENG as a self‐powered memory system for recording a mechanical displacement/trace. The output voltage produced by the TENG during motion can polarize the dipole moments in the ferroelectric thin film. Later, by applying a displacement current measurement to detect the polarization density in the ferroelectric film, the motion information of the TENG can be directly read. The sliding TENG and the single‐electrode TENG matrix are both utilized for realizing the memorization of the motion trace in one‐dimensional and two‐dimensional space, respectively. Currently, the ferroelectric thin film with a size of 3.1 mm² can record a minimum area changing of 30 mm² and such resolution can still be possibly improved. These results prove that the ferroelectric polymer is an effective memory material to work together with TENG and thereby the fabricated memory system can potentially be used as a self‐powered displacement monitor.     

Stabilization of space charge polarization in ion-dispersed gate dielectric layer of organic transistors by ultraviolet illumination for write-once read-many memory

In this work, a new type organic field effect transistor (OFET) based write-once read-many memory (WORM) device was developed. The device uses an ultraviolet (UV) cross-linkable matrix polymer mixed with ionic compounds to form an ion-dispersed gate dielectric layer. Under an applied gate voltage bias, migration of cations and anions in opposite directions forms space charge polarization in the gate dielectric layer, resulting in change of the electrical characteristics. It is shown that, with UV illumination to cross-link the matrix polymer, the formed space charge polarization can be stabilized. Therefore, the OFET can be operated as a WORM with the applied voltage bias to define the polarization and in turn the stored data, and the UV illumination to stabilize the stored data.     

基于多层次LSTM网络的多智能体攻防效能动态预测模型

针对多智能体攻防体系存在多层次耦合、无规律涌现等特征而导致难以准确预测作战效能的问题,构建一种基于多层次长短时时间记忆(LSTM)网络的多智能体攻防效能动态预测模型。明确多智能体攻防的总体框架和作战流程,通过多主体NetLogo平台模拟红蓝智能体攻防对抗过程,以获取群体结构和作战效能在不同个体决策下的多层次演化数据。利用善于处理时序特征的LSTM网络来表征个体决策、群体结构和作战效能三层间的函数映射,并基于该映射关系进一步预测未来攻防作战效能与进程。上述建模方法已在多组仿真中证实了其可行性与有效性。实验结果表明,所建模型的作战效能预测误差仅在7%以内,对多智能体攻防的作战指挥和体系建设具有指导意义。     

NUMA结构的高效实时稳定的垃圾回收算法

针对非一致性内存访问架构(NUMA)在垃圾回收(GC)过程中存在大量的远程内存读写导致GC性能降低的问题,对GC过程的各个阶段进行分析与研究,提出了一种基于NUMA结构的高效实时稳定的GC算法。该算法首先基于NUMA结构改进传统分代GC机制的堆空间布局,然后通过控制GC过程中扫描活跃对象阶段的初始根对象选取、动态负载均衡阶段截取任务队列的选取以及复制活跃对象阶段对象复制位置的选取,大大减少GC过程中的远程访问次数。这种改进的GC机制对所有NUMA结构具有通用性。以Godson-3处理器的NUMA平台为例进行的实验结果显示,优化的GC机制极大地缩短了GC的时间,而且提高了应用程序的性能以及稳定性。在SPECjvm2008测试中,GC时间平均缩短了14.6%(GC总时间缩短4.1%~41.58%),应用程序的性能平均提升了4.68%(最高提升17.8%),应用程序的性能稳定性提升了76.2%。