Dynamics and manipulation of ferroelectric domain walls in bismuth ferrite thin films

Ferroelectric domain walls differ from domains not only in their crystalline and discrete symmetry, but also in their electronic, magnetic, and mechanical properties. Although domain walls provide a degree of freedom to regulate the physical properties at the nanoscale, the relatively lower controllability prevents their practical applications in nano-devices. In this work, with the advantages of 3D domain configuration detection based on piezoresponse force microscopy, we find that the mobility of three types of domain walls (tail-to-tail, head-to-tail, head-to-head) in (001) BiFeO₃ films varies with the applied electrical field. Under low voltages, head-to-tail domain walls are more mobile than other domain walls, while, under high voltages, tail-to-tail domain walls become rather active and possess relatively long average lengths. This is due to the high nucleation energy and relatively low growth energy for charged domain walls. Finally, we demonstrate the manipulation of domain walls through successive electric writings, resulting in well-aligned conduction paths as designed, paving the way for their application in advanced spintronic, memory and communication nano-devices.     

基于知识图谱的国内石墨烯研究分析与发展对策

以SCIE数据库中1994-2012年我国的石墨烯论文为研究对象,借助SCIE分析功能和信息可视化软件CiteSpace,对石墨烯文献进行计量和可视化分析。通过绘制知识图谱,展示了我国石墨烯研究的时间分布、空间分布、研究力量分布和主要研究领域,揭示了石墨烯的研究热点与应用领域,并就石墨烯研究的发展提出对策建议。     

基于测宽法的轨道移频信号检测的仿真分析

基于测宽法原理对轨道移频信号进行检测,通过测量波形零点间的波形宽度进而求出移频信号的一系列周期,分析这些周期从而可以得出移频信号的上边频、下边频、中心频率以及低频.同时对原有算法进行相应的更改,提高了其抗干扰能力以及精确度,并使用Matlab对改进后的算法进行仿真,验证了其可行性.此方法简单易行,具有很高的工程实用价值.     

Emotional energy and sub-cultural politics: alternative bands in post-1997 Hong Kong

The paper attempts to work out the link between the structuring of the public domain and hegemonic masculinities in contemporary Kerala, South India. Using the debates around an incident of sexual harassment that happened in 1999, it argues for a conjunctural understanding of the contemporary where various events and moments in history are replayed through narrativization and popular memory. The paper goes on to analyse the debates around the incident that produce a ‘narrative public domain’, to foreground the various notions of masculinity that construct and structure it in relation to notions of female sexuality and changing structures of family. These notions of masculinity could be, the paper argues, a starting point for a historical inquiry into Kerala's modernity – an inquiry that would throw light on the past and the ways in which the contemporary is produced through its historical legacies.     

信息共享空间研究的知识图谱分析

以CSSCI数据库收录的以信息共享空间为主题的论文为基础数据,通过Citespace3.8R1软件对相关引文数据和主题词数据进行处理,绘制出信息共享空间领域的知识图谱,并对其进行分析,得出我国信息共享空间领域的重要学术文献及学术代表人物、主要研究热点及研究前沿等。     

航空发动机参数采集系统的设计与研究

在对国内外现役飞机电子座舱显示系统研究的基础上,设计了一种DSP+FPGA结构的数据采集系统。能够采集航空发动机的各项参数,并且可应用于具有数字多功能显示器的新型电子座舱系统。系统有效的实现了各种信号的采集以及对频率信号的滤波。     

0Cr18Ni9不锈钢车削力试验研究

切削力是切削加工中的一种伴随现象,切削力的大小直接影响到刀具寿命、加工质量和加工效率。在分析车削力时域特征的基础上,通过0Cr18Ni9不锈钢的正交车削试验,研究了切削参数对切削力波动系数的影响规律。结果表明：动态性是车削力的基本属性,切向分力和进给分力是车削力的主要成分;切削用量三要素中,切削深度ap对进给分力波动系数Qf和切向分力波动系数Qc都有着显著的影响,两者随ap的变化趋势基本一致。     

An efficient method of addressing ectopic beats: new insight into data preprocessing of heart rate variability analysis

Heart rate variability (HRV) analysis is affected by ectopic beats. An efficient method was proposed to deal with the ectopic beats. The method was based on trend correlation of the heart timing signal. Predictor of R-R interval (RRI) value at ectopic beat time was constructed by the weight calculation and the slope estimation of preceding normal RRI. The type of ectopic beat was detected and replaced by the predictor of RRI. The performance of the simulated signal after ectopic correction was tested by the standard value using power spectrum density (PSD) estimation, whereas the results of clinical data with ectopic beats were compared with the adjacent ectopic-free data. The result showed the frequency indexes after ectopy corrected had less error than other methods with the test of simulated signal and clinical data. It indicated our method could improve the PSD estimation in HRV analysis. The method had advantages of high accuracy and real time properties to recover the sinus node modulation.     

英语写作中语块使用的实证研究

提高英语写作技能是英语教学的目标之一,但怎样提高写作水平是英语教学亟待解决的难题。将语块理论引入写作教学,为其提供了新的视角。采用SPSS17．0对140名学习者在写作中使用语块的数据分析,发现其特征如下：从语块使用频度上看,语块使用较少,仅占全文的1/3;从语块使用重复率上看,其重复率较高,接近语块总数的1/3,这表明学习者语块使用不够多样化,种类不丰富;从语块类型上看,短语语块使用较多,句子语块使用较少;从学习者水平上看,高分组限制语块使用较多,低分组固定语块使用较多。     

Longitudinal analysis of the environmental attitudes of university students

This article addresses the important questions that higher education institutions ask concerning their impact on their students’ sustainability-related attributes ‘How do our students’ worldviews change as they experience higher education with us?’ The process of monitoring such a dynamic entity is fraught with statistical complexity but may not be impossible for an institution willing to ask whether or not its educational efforts in ‘education for sustainability’, ‘education for sustainable development’ or ‘environmental education’, and campus sustainability developments, are paralleled by changes in the attitudes of its students. We describe here a longitudinal survey process based on the revised New Ecological Paradigm scale, with two cohorts of students, in three programmes of study, operating over four years, with multiple survey inputs by each student. We implemented the longitudinal analysis using a linear mixed-effects model and describe here the development and testing of this model. We conclude that higher education institutions can benchmark the sustainability attributes of their students and monitor changes, if they are minded to. We invite higher education practitioners worldwide to join us in further developing suitable research instruments, processes and statistical models, and in further analysing the assumptions that link higher education to sustainability and to global citizenship.