S-仿紧空间的开Fσ-遗传性

讨论了S-仿紧空间的开Fσ-遗传性,证明了正规S-仿紧空间的开Fσ-子空间是S-仿紧的。这一结果深化了K．Y．Al·Zoubi关于S-仿紧空间的开闭遗传性。     

信号包络在DSP系统中的实现

论述了采用Hilbert变换的方法提取信号包络的方法,对Hilbert变换进行了理论分析,并推导出在DSP(数字信号处理器)系统中实现的算法,通过MATLAB进行的仿真,结果表明达到了较好的效果。该方法可以替代硬件包络电路,具有很强的实际应用价值。     

Research on iterated Hilbert transform and its application in mechanical fault diagnosis

Multicomponent AM–FM demodulation is an available method for machinery fault vibration signal analysis, so a new method for mechanical fault diagnosis based on iterated Hilbert transform (IHT) is proposed. The principle of computing the asymptotically exact multicomponent sinusoidal model for an arbitrary signal by iterating Hilbert transform is introduced, and some properties of IHT are analyzed. Theoretical analysis for the generic two-component signal shows that there are limitations in the direct estimation of instantaneous frequencies via the phase signals of the previously obtained model. Therefore, a smoothed instantaneous frequency estimation (SIFE) method based on difference operator and zero-phase digital low-pass filtering is proposed, and then the accuracy and validity of this method have been proved by the simulation results. The analysis results of the mechanical fault signals show that the weak features of these signals can be efficiently extracted with the proposed approach.     

Architecture as a Dissident Practice: An Interview with Diller Scofidio + Renfro

For three decades architect Liz Diller and artist Ricardo Scofidio have been collaborating on projects that test the boundaries between art and architecture. They have done more than any other practice to champion interdisciplinary research and to advocate architecture as a wider form of cultural production. Olympia Kazi went to talk to Liz Diller to ask her if she thinks theory could really be dead, or merely in a ‘lull’. Copyright © 2009 John Wiley & Sons, Ltd.     

‘To Go Beyond or Not to Be’ Unsolicited Architecture: An Interview with Ole Bourman

The complex dynamics of today's architecture require a deep intellectual freedom. This is something that Dutch architectural critic Ole Bouman espouses through his provocative writings and lectures and his advocacy of ‘unsolicited architecture’. Luca Guido invited Bouman to reflect on what it means to be an architect today and how it might be possible to pursue critical practice beyond the conventional construction processes. Copyright © 2009 John Wiley & Sons, Ltd.     

Spaces of Freedom

The predicaments of the current global climate bring a new poignancy and focus to architecture. Emiliano Gandolfi , the curator of the much lauded ‘Experimental Architecture’ exhibition in the Padiglione Italia at the 2008 Venice Biennale, outlines how an emerging group of designers are redefining architecture as they seek to provide solutions that identify people's needs and address the exigencies of global warning, the environmental crisis and migration. Copyright © 2009 John Wiley & Sons, Ltd.     

Natural Methods of Interaction Or Natural Interaction in the Everyday Digital World

Computers, mobiles and automatised machines are so omnipresent that the means by which we interact with digital devices is now generally regarded as a given. Italian practice iO Agency, though, questions our use of mechanised interfaces and the language that they require us to learn. Valentina Croci explains how iO Agency has developed more natural ways for people to interact with digital environments through physical or tactile ‘triggers’. Copyright © 2008 John Wiley & Sons, Ltd.     

利用单幅变形光栅条纹图提取相位的方法研究

针对单幅变形条纹图的调制相位提取问题,提出了两种分别基于频移法和基于希尔伯特变换的相移法从变形条纹图中提取面形相位的改进方法,并对它们的性能进行比较分析。在频移法中,通过使用伸缩窗口傅里叶变换来优化基频的准确提取;在相移法中,采用软件的方法利用希尔伯特变换来实现物理上的相移,并结合了求平均相位斜率的的方法有效去除载波相位成份。两种方法的共同优点都是只需要拍摄单幅条纹图像,操作简单,计算复杂度不高,有利于快速测量,具有良好的应用前景。     

硬C-means聚类和DT-CWT变换的数字图像水印算法

为了提高数字水印图像的鲁棒性,提出一种基于硬C均值聚类和双树复小波变换域的图像水印算法。该算法对载体图像进行一层双树复小波变换分解,利用人类视觉特性对其2个低频子带进行硬C均值聚类划分,确定可嵌入信息区域。将二值水印图像信号经过Hilbert曲线置乱和降维,形成一维信号序列。利用图像自身局部相关性,调节水印嵌入强度并修改小波系数值,实现将水印嵌入到可嵌入信息区域。实验表明,该算法具有良好的透明性且对压缩、剪切、噪声和滤波等几何攻击具有高鲁棒性。     

基于振动信号HHT方法的GIS设备故障诊断

介绍了在江苏省电力公司江东门110 kV变电站内采集运行中GIS设备的振动信号,对振动信号降噪处理,运用了希尔伯特-黄变换（HHT）对降噪后的振动信号进行分析。比较信号的希尔伯特谱,得到各频率分量幅值随时间变化的情况;比较信号的边际谱,得到GIS设备的故障特征量。实测数据研究表明,HHT方法能有效地对GIS设备进行特征提取及故障诊断。