OFDM系统中基于线性预编码技术的均衡方法

在快速移动环境中,子载波间干扰(ICI)是恶化OFDM系统性能的重要因素。为抑制OFDM系统中的ICI,采用了一种基于线性预编码技术的迫零均衡方法,并对其在无冗余情形下的误码率(BER)性能进行了理论分析,推导出了BER最优的线性预编码矩阵的选取准则。仿真结果表明,在较高信噪比条件下,所用的方法能有效抑制ICI和显著改善OFDM系统的误码率性能。     

电子雷管在地铁隧道爆破降振中的应用

研究地铁隧道穿越十字路口和相邻燃气管线时,使用电子雷管的爆破方案及方法。利用电子雷管可以任意设置时间的特点,重点研究上、下台阶间及隧道间的最佳延时间隔时间。确定起爆的间隔时差,通过干扰错峰来达到减振的效果,使爆破振动对周围燃气管线的影响达到最小。     

城市建筑中移动通信信号的干扰抑制

城市建筑物的结构、高度和密度会对蜂窝移动通信产生影响,在多径扩散信道中产生宽带和窄带干扰。为此,设计一种次优化的盲最小均方误差检测器。在抑制通信系统中宽带干扰(多址干扰和码间干扰)的同时,消除窄带通信系统产生的窄带干扰(包括正弦波信号、自回归信号、多速信号系统中的数字信号等)以及环境噪声,利用子空间分解技术和辅助向量来简化传统检测器。仿真结果证明,当信噪比为10 dB时,该检测器的误码率比传统检测器低约3 dB。     

基于小麦碰撞声音的霉变区域识别仿真分析

研究小麦霉变区域的识别优化问题,由于小麦霉变粒、受损颗粒与完好粒的物理构造不同,碰撞声信号与正常小麦信号一定存在差异。差异特征各项属性很容易受到外部噪声的干扰发生改变,造成传统的模式识别方法很难准确识别。提出了一种加入干扰分类去除因子的小麦碰撞差异特征霉变识别方法。在小麦碰撞过程中,确定分类决策因子,并且将小麦碰撞声音的残差平方和SSE引入核函数,设计一个小麦碰撞约束超平面,确保碰撞中的系数特征点中的正类输入以及负类输入,分别处于该约束超平面的两端,实现对霉变小麦碰撞特征的干扰消除。实验表明,改进算法实现了小麦霉变区域的特征识别的优化。     

NbO/Nb2O5 core–shells by thermal oxidation

Niobium oxides have been reported as an alternative to tantalum, and its oxide, for the production of capacitors, but these materials still require a further and exhaustive study. Understanding the dynamics of the oxidation process from NbO to Nb₂O₅ is essential to explain and control the properties of a niobium oxide based capacitors. In situ XRD analysis of NbO powders was performed from 100 to 1100 °C, which showed a temperature range where only amorphous phase is present. The capacitor anodes, formed from the same type of NbO powders, were then heat-treated in air from room-temperature (RT) to 550 °C and recorded with a video camera to see the colour shift. The presence of core–shell structures and the increase of the shell thickness/amount with temperature are visible in SEM. Finally, in situ spectroscopy studies were performed, in order to observe the interference spectra which are responsible for the observed colours.     

In‐Depth Study of Mass Transfer in Nanoporous Materials by Micro‐Imaging

The first application of interference microscopy to monitoring mass transfer in nanoporous materials dates back to late 1970s when Caro and colleagues reported results of investigations of water uptake by LTA type zeolites. It was, however, not before the beginning of the new millennium that the developments in both the measuring technique and computational power have enabled the recording of transient guest profiles during molecular uptake and release under well‐defined conditions, leading to the establishment of a novel access to diffusion studies, now referred to as micro‐imaging. In the present contribution, the thus accessible novel type of information is illustrated by an in‐depth analysis of the uptake kinetics of methanol in an all‐silica ferrierite. In particular, two remarkable experimental findings are reported, which may be tracked back to their microstructural and/or microdynamic origin, namely a pronounced asymmetry in the transient concentration profiles and a slowing down of guest uptake with increasing temperature.     

卷制衬套过盈度的分析

本文讨论了薄壁卷制衬套过盈配合的设计方法，并给出了测量时过盈度的计算方法。设计实例分析结果表明所给出的计算方法能够有效地应用于这类衬套设计与制造质量的控制。     

Practical application of the “turbid water” flag in ocean color imagery: Interference with sun-glint contaminated pixels in open ocean

A simple method to identify turbid, sediment-loaded, waters within satellite ocean color imageries was recently proposed (A. Morel and S. Bélanger, Remote Sensing of Environment, 102, (2006), 237-249). Systematic application of this method to the level-3 composites obtained from three ocean color sensors shows that the “turbid” flag is often raised in the open ocean, especially in the sub-tropical oligotrophic gyres, where turbidity is unlikely. In addition these flagged zones migrate with season, and clearly follow the sun declination course. The combination of low chlorophyll waters with a residual sun-glint is at the origin of this artifact. Simple approaches for eliminating such a misleading detection are proposed. The identification and elimination of the bias are also needed in particular for an unambiguous detection of the presence of calcite (coccolithophores) in open waters.     

FRESH-DFE: A New Structure for Interference Cancellation

This paper proposes a new structure of decision feedback equalizer that exploits the cyclostationary properties of digitally modulated signals to mitigate interference. In the proposed structure, the forward filter of the conventional DFE is replaced by a cyclic filter. It is assumed that the desired and the interference signals use some mutually different signaling attributes, for example symbol rates, centre frequency etc. The resulting structure is evaluated in the presence of up to six strong interfering signals, a scenario that is typically found in wireless cellular systems. The proposed structure provides performance gains for some modulation formats but it reduces to the conventional DFE for other signal formats.