Short-range Climate Prediction Experiment of the Southern Oscillation Index Based on the Singular Spectrum Analysis

The Southern Oscillation Index (SOI) time series is analyzed by means of the singular spectrum analysis (SSA) method with 60-month window length. Two major oscillatory pairs are found in the series whose periods are quasi-four and quasi-two years respectively. The auto-regressive model, which is developed on the basis of the Maximum Entropy Spectrum Analysis, is fitted to each of the 9 leading components including the oscillatory pairs. The prediction of SOI with the 36-month lead is obtained from the reconstruction of these extrapolated series. Correlation coefficient between predicted series and 5 months running mean of observed series is up to 0.8. The model can successfully predict the peak and duration of the strong ENSO event from 1997 to 1998. It's also shown that the proper choice of reconstructed components is the key to improve the model prediction.

A Note on the Prime Spectrums of Character Rings of Finite Groups

Let G be a finite group with order g and S be a subring of the algebraic number field which contains the integral extension over Z generated by a g-th primitive root co of unity, and R（G） be the character ring of G. The prime spectrum of the commutative ring S×Z R（G） iv denoted by Spec（S×Z R（G）） and set π={p｜p is a rational prime number such that p^-1 S}. We prove that when G is a regroup, a π＇-group, or a finite Abelian group, the number of the connetted components of Spec（ S×Z R （G） ） coincides with the number of the π-regular classes in G,

The Use of Aloe vera as Natural Coagulant in Algerian Drinking Water Treatment Plant

The purpose of this work is the study the ability of the plant material Aloe vera to act as natural coagulant using raw water obtained from a drinking water treatment plant(Mila,Algeria).Different solvents such as:NaCl;NaOH and HCl were used as chemical activators to extract the active components from the Aloe vera plant,and different coagulation-flocculation experiments were conducted in a jar test apparatus to evaluate the perfor-mance of the extracted coagulant.Also,the effect of coagulant dose on some water parameters such as turbidity,pH,total alkalinity and organic matter were investigated.The results showed that the use of coagulants obtained by using different solvents increases the coagulation efficiency compared to the coagulant obtained from the raw material,for example the maximum turbidity removal efficiency was 28.23,78.07,83.46 and 85.15%when using powdered Aloe vera(raw material),AV-NaCl(0.5 M),AV-NaOH(0.05 M)and AV-HCl(0.05 M),respectively.The results defined,that the residual turbidity obtained in this work,where the Aloe vera was used(after treat-ment by solvents)produced a turbidity lower than the Algerian standard(5 NTU)with initial turbidity(13 NTU).In this study,the infrared spectrum study and analysis has revealed the presence of different functional groups,which are responsible for the coagulation process.

Photosynthetic Characteristics of Flag Leaves in Rice White Stripe Mutant 6001 During Senescence Process

Physiological, biochemical and electron microscopy analyses were used to investigate the photosynthetic performance of flag leaves in rice white stripe mutant 6001 during the senescence process. Results showed that the chlorophyll content at the heading and milk-ripe stages in rice mutant 6001 were about 34.78% and 3.00% less than those in wild type 6028, respectively. However, the chlorophyll content at the fully-ripe stage in rice mutant 6001 was higher than that in wild type 6028. At the heading stage, the net photosynthetic rate （Pn） in rice mutant 6001 was lower than that in wild type 6028. Rice mutant 6001 also exhibited a significantly slower decrease rate of Pn than wild type 6028 during the senescence progress, especially at the later stage. Furthermore, Ca2^-ATPase, Mg~^-ATPase and photophosphorylation activities exhibited the similar trends as the Po. During the senescence process, the 68 kDa polypeptide concentrations in the thylakoid membrane proteins exhibited a significant change, which was one of the critical factors that contributed to the observed change in photosynthesis. We also observed that the chloroplasts of rice mutant 6001 exhibited higher integrity than those of wild type 6028, and the chloroplast membrane of rice mutant 6001 disintegrated more slow during the senescence process. In general, rice mutant 6001 had a relatively slower senescence rate than wild type 6028, and exhibited anti-senescence properties.

Response Spectrum Method for Extreme Wave Loading With Higher Order Components of Drag Force

Response spectra of fixed offshore structures impacted by extreme waves are investigated based on the higher order components of the nonlinear drag force. In this way, steel jacket platforms are simplified as a mass attached to a light cantilever cylinder and their corresponding deformation response spectra are estimated by utilizing a generalized single degree of freedom system. Based on the wave data recorded in the Persian Gulf region, extreme wave loading conditions corresponding to different return periods are exerted on the offshore structures. Accordingly, the effect of the higher order components of the drag force is considered and compared to the linearized state for different sea surface levels. When the fundamental period of the offshore structure is about one third of the main period of wave loading, the results indicate the linearized drag term is not capable of achieving a reliable deformation response spectrum.

Trend analysis of relative sea level rise or fall of the tide gauge stations in the Pacific

On the basis of the analytical results of the period components of monthly mean sea level of 236 stationsin the Pacific, the period components plus linear trend are ed to fit the monthly mean sea level series. The statisticalresults of linear trend Coefficients of these stations indicate that, if the abnormal values of sea-level rise and fall are neglected, the average rise rate of relative sea level in the Pacific is 1. 16 mm/a. Affected by nonuniformity Of land subsidence and other factors, the regional change of relative sea level rise or fall in the Pacific is greater. In the light of thepositive or negative values of linear trend coefficients as well as the geographical position of the sea area, zoning is madeof the sea level rise or fall in the Pacific including the coastal areas of China and Southeast Asia to obtain the averagerate of rise or fall in each sea area. The rise or fall trends of relative sea level obtained for the entire Pacific Ocean,west coast of North America, the northern and central South America, the greater part of the tropical Pacific and thecoastal Islands of Japan are basically in keeping with the other relevant results. The regional average estimated result ofthe relative sea level in the coast of East Asia is on the rise while the estimated results provided by Barnett tend todrop; the main cause of this nonuniformity is the number of stations selected and the distributional density.

Spectrum Detection of Rice Planthopper Populations from Canopy Reflectance Based on Principal Component Regression

[ Objective] Aiming at problems of early warning for occurrence of rice pests and dynamic monitoring of rice planthopper in field, a detection model for rice planthopper populations was established based on PCR with spectrum detection technology, r Method] Canopy reflectance data were collected using FieldSpeo 3 spectrometer in paddy field, and rice planthoppers populations in hundred hills were detected simultaneously. The sample size was 71, and there were 51 samples in the calibration set and 20 samples in the prediction set. Modeling band was 350 -1 139 nm, and the original spectra were pretreated by first order differential. [ Result] The correlation coefficient of measured values and predictive values was 0. 78, and the RMSEP was 161. [ Conlmion] Spectrum detection was able to be used in investigation and forecasting of rice planthoppere.

Time-frequency response spectrum of rotational ground motion and its application

The rotational seismic motions are estimated from one station records of the 1999 Jiji （Chi-Chi）, Taiwan, earthquake based on the theory of elastic plane wave propagation. The time-frequency response spectrum （TFRS） of the rotational motions is calculated and its characteristics are analyzed, then the TFRS is applied to analyze the damage mechanism of one twelve-storey frame concrete structure. The results show that one of the ground motion components can not reflect the characteristics of the seismic motions completely; the characteristics of each component, especially rotational motions, need to be studied. The damage line of the structure and TFRS of ground motion are important for seismic design, only the TFRS of input seismic wave is suitable, the structure design is reliable.

A decomposition method of nuclear magnetic resonance T2 spectrum for identifying fluid properties

Based on analysis of NMR T2 spectral characteristics,a new method for identifying fluid properties by decomposing T2 spectrum through signal analysis has been proposed.Because T2 spectrum satisfies lognormal distribution on transverse relaxation time axis,the T2 spectrum can be decomposed into 2 to 5 independent component spectra by fitting the T2 spectrum with Gauss functions.By analyzing the free relaxation response characteristics of crude oil and formation water,the dynamic response characteristics of the core mutual drive between oil and water,the petrophysical significance of each component spectrum is clarified.T2 spectrum can be decomposed into clay bound water component spectrum,capillary bound fluid component spectrum,micropores fluid component spectrum and macropores fluid component spectrum.According to the nature of crude oil in the target area,the distribution range of T2 component spectral peaks of oil-bearing reservoir is 165-500 ms on T2 time axis.This range can be used to accurately identify fluid properties.This method has high adaptability in identifying complex oil and water layers in low porosity and permeability reservoirs.

Analysis of volatile components in a Chinese fish sauce,Fuzhou Yulu, by gas chromatography-mass spectrometry

Volatile components of Fuzhou Yulu, a Chinese fish sauce, were analyzed by gas chromatography-mass spectrometry （GC-MS）, and two pretreatment methods, i.e., purge and trap （P＆T） GC-MS and ethyl acetate extraction followed by GC-MS, were compared. P＆T-GC-MS method determined 12 components, including sulfur-containing constituents （such as dimethyl disulfide）, nitrogen-containing constituents （such as pyrazine derivatives）, aldehydes and ketones. Ethyl acetate extraction fol- lowed by GC-MS method detected 10 components, which were mainly volatile organic acids （such as benzenepropanoic acid） and esters. Neither of the two methods detected alcohols or trimethylamine. This study offers an important reference to determine volatile flavor components of traditional fish sauce through modem analysis methods.

Sparse flight spotlight mode 3-D imaging of spaceborne SAR based on sparse spectrum and principal component analysis

The spaceborne synthetic aperture radar(SAR)sparse flight 3-D imaging technology through multiple observations of the cross-track direction is designed to form the cross-track equivalent aperture,and achieve the third dimensionality recognition.In this paper,combined with the actual triple star orbits,a sparse flight spaceborne SAR 3-D imaging method based on the sparse spectrum of interferometry and the principal component analysis(PCA)is presented.Firstly,interferometric processing is utilized to reach an effective sparse representation of radar images in the frequency domain.Secondly,as a method with simple principle and fast calculation,the PCA is introduced to extract the main features of the image spectrum according to its principal characteristics.Finally,the 3-D image can be obtained by inverse transformation of the reconstructed spectrum by the PCA.The simulation results of 4.84 km equivalent cross-track aperture and corresponding 1.78 m cross-track resolution verify the effective suppression of this method on high-frequency sidelobe noise introduced by sparse flight with a sparsity of 49%and random noise introduced by the receiver.Meanwhile,due to the influence of orbit distribution of the actual triple star orbits,the simulation results of the sparse flight with the 7-bit Barker code orbits are given as a comparison and reference to illuminate the significance of orbit distribution for this reconstruction results.This method has prospects for sparse flight 3-D imaging in high latitude areas for its short revisit period.

Feature spectrum extraction of human fingernails based on LCTF multispectral imaging

A multispectral imaging system consisting of liquid crystal tunable filter(LCTF)and charge coupled device(CCD)camera was used to collect the images of fingernail samples at intervals of 10 nm during the spectral range of 450-1 000 nm,and a multispectral image of human fingernails containing 56 bands was obtained.The accurate reflectivity information of fingernails was obtained through referring whiteboard comparative measurement method.Principal component analysis(PCA)and band index method were used to reduce the dimension of the sample images respectively and two feature spaces were obtained.Spectral angle mapping(SAM)was used to classify human fingernails in these two feature spaces.The classification accuracy were above 92.5%and 82.9%respectively.Therefore,the feature space obtained by the PCA can be used as the characteristic spectrum of human fingernails,which provides a reliable basis for the analysis of multispectral spectrum of fingernails and human health assessment in the future.

Determination of Fourier Components of Spatial Correlation Function of Dielectric Susceptibility of Random Medium

In this work, we present a new method of directly determining Fourier components of the spatial correlation function of the dielectric susceptibility of random medium. The method is based on the analysis of the ratio of the spectrum of the light scattered by the spatial correlation components of the dielectric susceptibility of tissue to the spectrum of light scattered by the randomly distributed scatterers which are independent on the value of the spectrum of the incident light and the direction of the observation. The results may find wide applications in areas such as in biomedical diagnosis.

手性分子构象分析装置圆二色光谱仪的加强与改造

圆二色光谱仪是对手性分子进行构象分析和理化性质表征的重要仪器.然而长期高强度的使用会产生光谱仪光学元件劣化、检测器灵敏度降低等问题.通过优化分光系统的光学元件提升光传输效率,升级具有更高量子效率的大面积雪崩硅光电二极管检测器,进而大幅提高仪器信噪比,同时将测量波长范围从175~900 nm扩展到175~1150 nm.在氙灯被点燃之前用氮气彻底净化仪器,把氧气排除在光谱仪之外是非常重要的操作步骤.安装具有监视、计划、流量设置、报警和辅助控制等功能的活性氮监测系统,可以实时监测控制仪器内部氮气吹扫情况.通过升级改造,既加强了仪器的性能,又节省了氮气消耗成本,同时仪器使用寿命将进一步延长.

数字T/R组件发射频谱控制技术研究

现代武器装备单平台集成的各频段雷达、通信等无线电设备数量越来越多,且发射信号均向高功率、超宽带等方向发展,使得雷达与其他设备之间的发射频谱交叠严重,进而导致不同设备之间存在严重的电磁干扰问题。文中针对不同无线电设备收发信号之间的电磁干扰问题进行了分析,重点讨论了数字T/R组件脉冲发射带外频谱分量的产生机理和改善方法,提出了针对性的频谱控制措施,并在某雷达数字T/R组件上开展了试验验证,证明了该频谱控制方法的有效性。

不同贮藏温度及包装条件对乌天麻干片挥发性气味的影响

采用电子鼻及吹扫捕集-气相色谱-质谱联用技术(purgeand trap-gaschromatography-massspectrometry,PT-GC-MS)分析3个贮藏温度(10、25、40℃)及4种包装条件(空气、N_(2)、CO_(2)、脱氧)对乌天麻干片的挥发性气味的影响。结果表明:在120 d的贮藏期内,不同温度及包装下的乌天麻干片挥发性气味存在一定的差异。温度是影响贮藏期乌天麻干片挥发性气味最主要的因素,低温更有利于保持乌天麻干片挥发性成分。其次是包装条件,在同一温度条件下,脱氧处理更有利于保持乌天麻干片的挥发性气味。随着贮藏时间的延长,不同温度及包装条件下,乌天麻干片中挥发性物质在种类和含量上均发生变化,在120 d贮藏期内,10℃脱氧处理组共检测出挥发性成分29种,总含量为214.52μg/g,醇类占总挥发性成分的54%;酯类占总挥发性成分的14%;烷烃类占总挥发性成分的10%;与对照组的挥发性成分最为接近。综上所述,10℃脱氧包装为乌天麻干片最佳贮藏条件,在该条件下贮藏,乌天麻干片的风味成分损失最小,可在较长贮藏期内有效保留乌天麻干片的风味成分。

顾及信号振荡特征的慢滑移信息时空提取

针对传统滤波和固定函数拟合等方法探测慢滑移信号时易产生信息误剔除或伪信号提取等问题,提出一种基于信号振荡特征的慢滑移时空信息探测方法:利用多通道奇异谱分析分解坐标序列;然后根据慢滑移位移特征确定信号的起止时间;最后基于信号的振荡方向和振幅归一化明确空间响应方向和强度。仿真结果表明,相较于主成分分析和独立成分分析,该方法在探测慢滑移起止时间、空间响应方向和强度等方面优势明显:实际应用中,利用该方法成功探测出新西兰马纳瓦图的慢滑移事件,测站WANG和PNUI连线两侧的空间响应方向相反,强度大,地震危险性高;而独立成分分析和主成分分析探测到的空间响应可能受到共模误差影响,时间响应也无法明确慢滑移起止时间。

一种波段聚类和多尺度结构特征融合的高光谱图像分类模型

高光谱图像包含丰富的地物信息,在农业、工业和军事等领域应用广泛。因此,高光谱图像的识别与分类是一项重要的研究课题。然而,高光谱图像存在光谱维度高、噪声大、标记样本有限等问题,并未取得很好的分类效果。针对以上问题,提出一种波段聚类和多尺度结构特征融合的高光谱图像分类模型(ASPS-MRTV)。该方法主要包括以下几个步骤,首先,对高光谱数据进行归一化处理,将归一化后的三维图像按光谱维等分为n个子空间;其次,采用粗细划分策略构造自适应子空间光谱特征提取框架,将每个空间波段拉伸为一维向量后用信息散度构造波段的相似性矩阵,按照聚类的思想对n个子空间进行自适应;然后,将每个自适应子空间的光谱波段平均值进行叠加,形成光谱特征;最后,对所得到的光谱特征数据利用多尺度相对全变分技术提取结构特征。为了增强样本的线性可分性,在数据堆叠之后进行核主成分分析,最终形成空谱特征。对比实验中统一使用惩罚参数C和核参数σ都为24.5的SVM进行分类。经测试,ASPS-MRTV网络模型在Indian Pines、 University of Pavia两个数据集上分别以5%, 1%的训练样本达到了97.06%、 98.98%的总体分类精度。实验结果表明,该模型与SVM、 ASPS(ED)、 ASPS(ID)、 ASPS-LBP、 ASPS-GlCM、 ASPS-BF模型相比,在分类性能和计算效率方面都取得了更优的效果,有效提高小样本下高光谱图像的分类精度。

基于WP-ICA分析的涡旋压缩机故障特征提取方法研究

针对涡旋压缩机故障特征难以提取以及在小样本下故障类别难以区分的问题,提出了一种基于小波包能量谱与独立成分分析相结合的故障特征提取方法,结合支持向量机建立故障分类模型,实现非平稳信号的准确识别。首先对信号进行小波包分解与重构,通过重构系数获取分解后不同频带所对应的小波包能量作为故障特征值;再利用独立成分分析法对故障特征值进行优化得到特征向量值;最后构造支持向量机,输入故障特征向量进行训练和测试,可得出涡旋压缩机故障诊断的准确率。实验和仿真分析结果验证了该方法的有效性,其诊断准确率可达94.5%。

基于顶空气相色谱-离子迁移谱的不同品种香稻米快速鉴别方法

采用气相色谱-离子迁移谱(gas chromatography-ion mobility spectrometry,GC-IMS)技术原理,分析“牡育稻78号”、“牡科稻5号”、“牡科稻7号”3种香稻米中挥发性成分的组成,结合主成分分析(principal component analysis,PCA)进行统计分析。结果发现:辛醛单体、辛醛二聚体、6-甲基-5-庚烯-2-酮在“牡科稻5号”中含量最少,在其它样品中差异不大;罗勒烯、柠檬烯单体、柠檬烯二聚体在“牡育稻78号”中含量最多;乙醇、二甲基-1-丁醇在“牡科稻7号”中含量最多。主成分分析表明,不同品种香稻米挥发性气味成分在气相色谱-离子迁移谱上呈现出一定差异,两个主成分累计贡献率达到84%,说明基于GC-IMS技术可以实现不同品种香稻米的区分。