ANALYSIS OF LEAST SQUARES SMOOTHING OPERATORS IN THE FREQUENCY DOMAIN*     

S. H. CHAN  L. S. LEONG 《Geophysical Prospecting》1972,20(4):892-900

The process of data smoothing by least squares operators with real and symmetric coefficients is shown to be equivalent to linear digital filtering. Study of the frequency response functions of the least squares operators shows that these operators are essentially low-pass filters. The frequency response functions are characterized by the presence of a main lobe centered about the zero frequency together with a number of minor lobes of smaller amplitudes at higher frequencies. The predominant band of frequencies which is passed by a least squares operator occurs within the main lobe of the frequency response function. The filtering characteristics of a least squares operator are dependent on the degree of the polynomial and the number of data points. Generally speaking, the higher the degree of the polynomial the broader the pass band of the filter will be. But the effect of the number of data points on the pass band is exactly opposite. Several figures showing the plots of the half-power frequency, the quarter-power frequency, and the half-width of the main lobe for a large number of least squares operators with different combinations of the degree of the polynomial and the number of data points are presented in this paper. These figures will be helpful to those people who wish to make a selection of least squares operators suitable for their purposes.  相似文献   

Origin of the springtime tropospheric ozone maximum over east China at LinAn in 2001   总被引：2，自引：0，他引：2  

C. Y. CHAN  L. Y. CHAN  H. CUI  X. D. ZHENG  Y. G. ZHENG  Y. QIN  Y. S. LI 《Tellus. Series B, Chemical and physical meteorology》2003,55(5):982-992

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Effects of the Indo-China Peninsula Heat Fluxes on the 1998 South China Sea Summer Monsoon          下载免费PDF全文

SHI Xueli  Johnny C. L. CHAN  K. C. CHOW  DING Yihui 《Acta Meteorologica Sinica》2005,19(4):457-468

1. IntroductionBecause the South China Sea (SCS) is one of theregions where the Asian summer monsoon onset oc-curs earliest, the SCS summer monsoon (SCSSM) hasalways been a research focus, especially in recent yearswith the implementation of the SCS Monsoon Exper-iment (SCSMEX) (e.g., Tao and Chen, 1987; Changand Chen, 1995; Lau et al., 2000; Ding and Li, 1999;Ding and Liu, 2001; Li and Wu, 2000; Xie et al., 1998;Zhang et al., 2004). Climatologically, the SCSSM on-set is a rem…  相似文献   

Intraplate earthquakes in Northern Svalbard     

W.Winston Chan  B.J. Mitchell 《Tectonophysics》1985,114(1-4)

A temporary network of microearthquake seismographs deployed in the northern part of Svalbard recorded numerous earthquakes during the summer of 1982. Most of the earthquakes occurred in concentrated zones in restricted portions of three fault complexes in central Nordaustlandet, but minor activity also occurred to the east and west of these complexes. Within the uncertainty of the epicentral locations, most earthquakes which occurred on land in regions not covered by glaciers could be associated with segments of mapped faults. There are numerous fault segments and even entire faults, however, along which no recorded earthquake occurred. The concentrated spatial locations of these earthquakes along preferred portions of mapped faults, and the absence of throughgoing lines of activity, suggest that these are intraplate earthquakes occurring along existing faults in response to an applied stress field. Composite fault-plane solutions for the three most active regions each include one nodal-plane which can be associated, at least roughly, with a trend of seismicity and trend of a mapped fault. The directions of greatest principle stress for the three fault plane solutions vary between N90°W and N55°W, directions which agree approximately with maximum stress directions determined for a region about 200 km to the south. The consistency of the directions of maximum principle stress obtained for earthquakes throughout a broad region of Svalbard suggests that the earthquakes there occur in response to a stress field which is of plate tectonic origin.  相似文献   

香港九龙大坑东地下蓄水方案数值研究          下载免费PDF全文

匡翠萍  李行伟  陈孝章  Peter Clark  Nick Townsend  Raymond Siu 《水科学进展》2006,17(3):334-341

香港九龙大坑东地下蓄水方案(Tai Hang Tung Storage Scheme-THTSS)是香港西九龙渠道改善二期计划的一个重要组成部分,其目标是解决香港九龙繁华拥挤、人口稠密的商业中心旺角一带的洪水淹没问题。THTSS即是在经常洪水淹没区域(大坑东和界限街水渠交接处)上游足球场下面建立一个100 000 m3的地下蓄水池。本文建立了一个能处理明渠缓流和急流、封闭管道有压流、侧流堰和渠道汇合处过渡流于一体的一维水力数学模型,用1:22正态物理模型恒定流下的结果进行验证。数值模型计算了在50年一遇暴雨下,非恒定洪水在不同的侧流堰方案下的流动过程。结合物理模型试验结果,选择最佳的地下蓄水方案。计算结果表明,大坑东地下蓄水方案确实能加强旺角地区地洪水控制能力,并能通过50年一遇暴雨的洪水。  相似文献   

徐宿弧(安徽段北部)弱磁异常特征及其认识   总被引：2，自引：2，他引：0       下载免费PDF全文

何柳昌  产思维 《中国地质调查》2018,5(1):60-65

查明徐宿弧(安徽段北部)隐伏岩体的赋存状况,圈定岩体与围岩的接触部位及找矿靶区并推测赋矿部位,是实施徐宿弧(安徽段)金多金属矿成矿背景调查的主要任务。徐宿弧(安徽段北部)为弱磁异常区,实测磁异常形态凌乱且难以识别。首先通过化极、滑动平均、匹配滤波、垂向一阶导数及向上延拓等方法进行多方法多参数变换数据处理,从弱磁异常中提取形态规则、易于识别的低缓异常; 然后对处理结果进行甄别对比,筛选出异常形态特征有利于地质解释的磁异常图,即: 低缓磁异常为叠加异常,总体呈NW方向延伸,覆盖面积较大,次级异常呈NNW-NE方向西凸的弧形延伸至前欧盘。同时,依据徐宿弧(安徽段北部)的地质背景及岩(矿)石磁性参数特征,通过对比分析实测磁异常与前欧盘闪长玢岩引起的磁异常特征,推测引起低缓异常的磁性地质体为隐伏中酸性复式岩体。该研究为徐宿弧(安徽段)金多金属矿成矿背景调查的综合解释及圈定找矿靶区提供了参考。  相似文献   

徐宿弧(安徽段)深部重磁异常及其认识     

王金鑫  何柳昌  产思维 《安徽地质》2021,31(1):40-43

为调查徐宿弧(安徽段)隐伏基底构造及深部隐伏岩体的分布,对深部重磁异常进行了分析判断.通过对收集、实测的重磁资料进行整理、筛选,采用化极、向上延拓、小波变换及水平一阶方向导数等进行数据处理;根据深部重磁异常特征结合区内的岩矿石物性特征及成矿地质背景分析,推测了铁佛寺-濉溪县-庄里的北东-北北东向隐伏基底构造及旗杆楼-萧县的东西向隐伏基底构造;新圈定了庄里深部隐伏复式岩体及淮北深部隐伏岩体,为徐宿弧(安徽段)地区进行矿产预测,提取示矿信息提供依据.  相似文献   

厚覆盖区找矿“循环渐近式勘查技术体系”与应用     

汪青松  张金会  张顺林  张家嘉  产思维  程培生  崔先文  张凯 《地质论评》2021,67(4):67041129-67041146

覆盖区找矿难度不仅与覆盖层厚度有关,还与覆盖层物性、水文地质条件以及矿体特征关系密切。覆盖区找矿突破是一个系统过程,需要经历选区—圈靶—定位—验证评价4个阶段,存在勘查选区、地质信息探测和多学科有效融合难题。前人较少研究覆盖区找矿突破过程与勘查技术体系,笔者等基于"现有技术+结合实际创新"思路,总结提出了厚覆盖区找矿"循环渐近式勘查技术体系",在实际应用中,能够提高找矿成功率,入选自然资源部《矿产资源节约和综合利用先进适用技术目录(2019年版)》。  相似文献   

Metabolism and mutagenicity of 4-nitroquinoline N-oxide by microsomes and cytosol of digestive gland of the mussel Mytilus edulis L.     

Paz Garcia-Martinez  Antal K.D. Hajos  David R. Livingstone  Gary W. Winston   《Marine environmental research》1992,34(1-4)

The modulation of the mutagenicity of 4-nitroquinoline N-oxide (4-NQO) by M. edulis digestive gland cytosolic and microsomal fractions was studied by monitoring the induction of the umu operon by 4-NQO in Salmonella typhimurium 1535/pSK1002. The mutagenicity of 4-NQO was increased by M. edulis cytosol and microsomes in dose-dependent manner with respect to protein and toxicant concentration. The mutagenic enhancement reflected increased NAD(P)H-dependent oxygen consumption by microsomes in the presence of 4-NQO and enhanced nitroreductase activity in cytosol. The former was stimulated by azide, indicating 4-NQO-enhanced oxyradical production by microsomes, and the latter was inhibitable by dicoumarol, indicating involvement of DT-diaphorase in nitroreduction by M. edulis cytosol. Neither dicoumarol nor allopurinol (inhibitors of DT-diaphorase and xanthine oxidase, respectively) affected the enhanced mutagenic expression of 4-NQO by cytosol. The results support the possibility of oxidative stress as a pollution-mediated mechanism of toxicity.  相似文献   

Ground–Space–Sky Observing System Experiment during Tropical Cyclone Mulan in August 2022     

Pak-wai CHAN  Wei HAN  Betty MAK  Xiaohao QIN  Yongzhu LIU  Ruoying YIN  Jincheng WANG 《大气科学进展》2023,40(2):194-200

Forecasting tropical cyclone track and intensity is a great challenge for the meteorological community, and safeguarding the life and property of people living near the coast is an important issue. One major reason for challenging forecasts is the lack of observations over the vast oceans. During tropical cyclone Mulan between 8 and 10 August 2022over the northern part of the South China Sea, the meteorological authority and research institutes of Chinese mainland collaborated with the meteorolo...  相似文献