Hanning自卷积窗函数及其谐波分析应用

提出一种新型窗函数——Hanning自卷积窗函数,构建了Hanning自卷积窗的时域、频域函数,分析了1~4阶Hanning自卷积窗函数的主瓣、旁瓣性能,建立了基于Hanning自卷积窗函数的频谱相位差校正算法,推导了信号基波与各次谐波频率、幅值和初相角计算式.Hanning自卷积窗具有优良的旁瓣性能,频谱函数简单,能有效抑制频谱泄漏的影响,频谱相位差校正算法不必求解高次方程,便于嵌入式系统实现.仿真结果表明：Hanning自卷积窗函数抑制频谱泄漏效果好,基于Hanning自卷积窗函数的频谱相位差校正算法克服了基波频率波动与白噪声对谐波分析的影响,谐波参数分析准确度优于经典窗函数.电力谐波分析与谐波电能计量应用实践证明了Hanning自卷积窗函数的有效性和优越性.     

基于奇异值分解的多小波图像去噪方法

给出了一种将多小波变换和奇异值分解相结合的图像去噪方法.该方法通过对含噪图像进行多小波变换,克服了单小波变换中无法同时满足正交性和对称性的缺点.对变换得到的高频系数矩阵进行奇异值分解去噪,提取高频系数中淹没在噪声中的信号成分,然后进行多小波重构,得到去噪图像.仿真结果表明,该方法能有效去除噪声,并获得良好的主观视觉效果.     

基于混合像元分解的遥感图像融合实用算法

传统的图像融合算法,如IHS变换、合成变量比、主成分替换等方法所得到的融合图像通常存在不同程度的光谱扭曲现象.一种基于混合像元分解的图像融合算法(FSMA)可以很好地保持图像的光谱信息,但该算法仅在以终端端元为先验知识的模拟数据中得到了成功的应用.分析表明,由于全色波段与多光谱波段光谱响应函数不同以及多光谱波段通常不能覆盖整个全色范围,原有的FSMA算法并不能直接应用到真实遥感数据中.文中提出了一种改进的基于混合像元分解的图像融合算法(IFSMA).该算法通过重构原有算法中优化问题的目标函数,降低了对利用多光谱数据模拟全色波段亮度值的难度,使得基于混合像元分解的图像融合算法可以推广应用到真实遥感数据中.实验结果表明,IFSMA算法在光谱信息和空间信息的保持方面均优于IHS变换、合成变量比、主成分替换以及原有的FSMA等算法.     

一种饱和电力系统稳定域估计的降阶方法

基于奇异摄动理论提出一种用于估计奇异饱和系统稳定域的降阶方法. 通过构造一个低维饱和系统来估计原高维饱和系统的稳定域, 不仅可以克服高维系统的奇异性, 还可以减少稳定域估计的计算量. 此外, 从理论上证明了降阶方法的严格性, 并利用3机5节点的算例验证了此方法的有效性.     

分数阶傅里叶域与时域联合干扰抑制研究

针对传统扫频干扰抑制方法存在信噪比损失大、输出信干噪比受输入干信比影响大导致同步性能不稳定、强干扰下频谱泄露严重等问题,提出了一种基于重叠变换的分数阶傅里叶域与时域联合干扰抑制技术.首先通过加窗、重叠分数阶傅里叶变换,提高干信比改善性能,降低信噪比损失;其次,通过弱化干扰与二次门限处理,在分数阶傅里叶域中尽可能多地抑制干扰能量,减小干信比对输出信干噪比的影响,最后,通过分数阶傅里叶域及时域联合干扰抑制,解决强干扰存在相位不连续造成分数阶傅里叶抑制后,时域仍残留干扰能量的问题.理论分析及仿真结果表明,本文所提方法对单个调频率多个周期扫频干扰和多个调频率扫频干扰均具有较好的抑制效果,尤其在高干信比下比传统方法性能改善明显.     

基于最优小波包分解的图像隐写通用检测

基于图像最优小波包分解,提出了一类具有较高检测正确率的信息隐写通用型检测方法.首先基于Shannon熵计算信息代价函数,对图像进行最优小波包分解,并从分解得到的子带系数以及图像像素中提取直方图特征函数多阶绝对矩作为特征,然后对提取的特征进行预处理并设计BP神经网络分类器进行分类.针对不同的背景和应用环境,文中给出了3种不同的检测算法.针对LSB、PMK、LTSB、Jsteg、F5及JPHide等典型隐写算法的实验表明:此方法相比现有的典型通用检测方法,正确检测率提高约6.4%～15.4%,且具有更好的通用性,并可为设计基于最优小波包分解的模式识别和分类算法提供参考.     

一种自适应频谱成形器:在超宽带认知无线电中的应用

超宽带脉冲无线电(UWB-IR)在高速通信、高精度定位及穿墙透地等重要领域具有广阔的应用前景,它与认知无线电结合将进一步缓解频谱资源的紧张局势.然而,现有的UWB脉冲难以充分利用其频谱能量,导致其传输性能下降;同时,UWB-IR无法有效而灵活地进行频谱规避,从而无可避免地干扰其余授权用户.从数学插值理论出发,本文基于径向基神经网络提出一种通用频谱成形滤波器,进行合理简化后给出其简单硬件实现.该脉冲设计网络能快速跟踪UWB设备的工作环境,自适应地设计具有特定频谱的UWB-IR脉冲.当无授权用户工作时,它能最大化频谱利用率,改善UWB系统传输性能;当有授权用户时,在最大化非授权频段能量利用率的前提下,它能有效地规避授权频段,实现可靠频谱共享.理论分析和仿真表明,基于神经网络的UWB脉冲在频谱利用率、频谱规避性能及接收性能等方面均优于现有设计方案.     

两步EFOP参数估计的递推算法

经验频域最优参数（EFOP）估计方法是基于时域估计和频域估计的一种系统辨识方法．其优点在于能够降低噪声影响，对小样本数据的随机系统具有较好的辨识效果．利用松弛算法而建立的两步EFOP方法，可适用于ARMA和Box-Jenkins等模型．文中对受干扰的随机系统，推导出两步EFOP方法的递推算法．对新的递推算法进行了仿真，并利用实验结果分析和验证了该算法的有效性．     

基于平行因子分析的频率、二维到达角和极化参数联合估计

文中基于平行因子分析、结合高阶累积量,提出了一种信源频率、二维到达角和极化参数联合估计的新算法。该算法给出了一种新的阵列结构;接着巧妙选择特定偶极子对的输出计算四阶累积量,进而构造高维矩阵;然后基于形成的矩阵在累积量域构造平行因子分析模型,并分析了该模型低秩分解的唯一性,最后利用其分解的结果联合估计信源参数。文中算法有效减小了阵列孔径损失、避免了参数配对。最后给出的仿真结果证实了文中算法的有效性。     

人工蜂群优化算法在复数盲源分离中的应用

针对复值信号的源数估计和有序分离等关键技术,提出一种基于人工蜂群优化的源数未知的复值盲源分离方法,该方法首先利用交叉互验技术来估算复数源信号的个数,然后通过人工蜂群算法优化峰度的绝对值来获得最佳分离向量,并实现了逐次恢复源信号的目的.仿真实验结果表明,该方法不仅能依峰度绝对值的降序实现服从任何分布源信号的盲分离,同时比其他方法具有更优越的估计性能.另外,提出一种基于峰度的欠定复盲源分离算法,该算法根据信号的统计特性构造了用于欠定混合情况下盲抽取向量的代价函数,然后通过人工蜂群算法优化其函数来获得最佳分离向量,通过多次分离来实现欠定复盲源分离的目的.通过对混合分布类型的复值源信号欠定盲分离仿真实验验证了该算法的有效性.     

Inherent properties and statistics with individual particles in quantum mechanics

This paper puts forward the hypothesis that the distinctive features of quantum statistics are exclusively determined by the nature of the properties it describes. In particular, all statistically relevant properties of identical quantum particles in many-particle systems are conjectured to be irreducible, ‘inherent’ properties only belonging to the whole system. This allows one to explain quantum statistics without endorsing the ‘Received View’ that particles are non-individuals, or postulating that quantum systems obey peculiar probability distributions, or assuming that there are primitive restrictions on the range of states accessible to such systems. With this, the need for an unambiguously metaphysical explanation of certain physical facts is acknowledged and satisfied.     

Implications of toxins in the ecology and evolution of plant pathogenic microorganisms: Bacteria

This review attempts to rationalise what is known about bacterial phytotoxins and associate it with the ecology and possible evolution of the producing organisms. Study of non-toxin producing variants gives insight into the ecological role of the toxin. Elucidation of chemical structures of phytotoxins has shown that many exist as families of analogous compounds. Studies on the variation of chemical structures and how they are distributed across species and genera can lead to development of hypotheses on evolutionary relationships. Knowledge on biosynthetic pathways to tosins allows recognition of specific enzymatic steps involved in developing the characteristic features of the structures. Phytotoxins often have a potent biochemical activity, and in some cases the producing organism has associated mechanisms to prevent action of the toxin upon itself; in such cases toxigenesis is clearly not a chance event. The various aspects of bacterial toxigenesis indicate that bacterial phytotoxins are special secondary metabolic products that play beneficial roles to the producing organisms in their various ecological niches.     

Instar-specific defensive secretions of stink bugs (Heteroptera: Pentatomidae)

Defensive secretions (allomones) from first-instar nymphs of stink bugs in the subfamily Pentatominae contain (E)-4-oxo-2-decenal as a major constituent, whereas this compound is absent from later instars. In contrast, first instars ofEdessa meditabunda (Edessinae) produce allomones like those of later instars. The C₆ and C₈ (E)-4-oxo-2-alkenals are common, characteristic exocrine compounds of nymphal and adult Heteroptera, but (E)-4-oxo-2-decenal is previously unknown as a major natural product for which a biological role has yet to be established.     

Spasmin-like proteins in various ciliates revealed by antibody to purified spasmins ofCarchesium polypinum

Summary It was found that some ciliates,Stentor, Spirostomum andBlepharisma, which can contract rapidly like the stalks of Vorticellidae, have Ca²⁺-binding proteins that are very similar to spasmins, in the immunological sense. The presence of spasmins in other Protozoa and in some Metazoa was also investigated.     

Observation and prediction in ancient astrology

What is the relationship between observations, predictions, texts, and instruments in ancient astrology? By distinguishing between two distinct kinds of observation claim in astrological texts, I show on the one hand the rhetorical and theoretical importance of each kind of observation claim to ancient astrological traditions, and on the other hand how practices of ancient astrology break from observation once astronomical phenomena become reliably predictable. We thus see a shift in practice from observationally derived predictions to a reliance on textual and instrumental authority, even though the rhetoric of ancient astrology still tries to maintain an emphasis on observation.     

Partial sequence of the gene for a serine protease from a halophilic archaeumhaloferax mediterranei R4, and nucleotide sequences of 16S rRNA encoding genes from several halophilic archaea

A part of the gene coding for a halophilic serine protease from a halophilic archaeumHaloferax mediterranei R4 was amplified by PCR and its 672 nucleotide sequence was determined. Tentative translation to the amino acid sequence suggested that the enzyme was quite similar to halolysin produced by another halophilic archaeum strain 172P1. Nucleotide sequences of 16S rRNA encoding genes from 9 halophilic archaea were determined. Alignment of 19 sequences known so far showed that there are more than 20 positions carrying bases or deletions specific for each halobacterial genus:Halobacterium, Haloarcula, Haloferax, andHalococcus.     

Anthelmintic activity of a benzimidazoline compound in sheep by abomasal infusion

Summary In vitro and in vivo data on the benzimidazoline compound indicate anthelmintic potential when introduced directly into the abomasum.     

Cognition wars

In what kinds of physical systems can cognition be realized? There are currently competing answers among scientists and theorists of cognition. There are many plant scientists who maintain that cognition can be realized in plants. There are biological scientists who maintain that cognition is materially realized in bacteria. In this paper, I will present the basis for such claims and evaluate them and discuss the future for theories of the metaphysical basis of cognition in the cognitive sciences.     

Mating attempts between the Scarlet Tiger Moth,Callimorpha dominula L., and the Cinnabar Moth,Tyria jacobaeae L. (Lepidoptera: Arctiidae), involve a common sex pheromone composition

It has been suggested that a common sex pheromone composition may account for interspecific sexual interactions observed with certain moths in the Arctiidae. In this study, it is demonstrated that the sex pheromones released by females of the Scarlet Tiger Moth,Callimorpha dominula L., and the Cinnabar Moth,Tyria jacobaeae L., have similar activities and elute at the same retention time on analysis by coupled gas chromatography (GC)-electrophysiology with males from each species. Peak enhancement on GC, chiral GC and coupled GC-mass spectrometry using authentic compounds show that the sex pheromone for bothC. dominula andT. jacobaeae is (3Z,6Z,9S,10R)-9,10-epoxyheneicosa-3,6-diene.     

Phenology of fruit and leaf production by ‘strangler’ figs on Barro Colorado Island,Panamá

Summary Fruit and leaf initiation by 26 trees representing five stranglerFicus species in the subgenusUrostigma were monitored for 5–8 years in a seasonal lowland forest of central Panamá. Individual trees of each species initiated fruit in synchronized crops. High variation in the number of crops, intervals between crops and dates of crop initiation indicate that these species, like species in the subgenusPharmacosycea, initiate fruit crops the year around. Nevertheless, mean crop initiation dates for four of five species fell within the four-month dry season. Similarly, all species produced new leaf flushes throughout the year, however, mean leaf flush dates of all species fell within the first three months of the dry season.