加权和不加权TLS方法及其在不等精度坐标变换中的应用

以重合点坐标独立但不等精度的三维坐标变换问题为基础,采用不加权和加权的TLS方法进行解算。模拟算例表明,未加权的简单TLS方法与基于残差的LS方法的估计结果一致。在加权方法中,按行分块独立的WTLS方法能达到最大似然估计精度,而EWTLS方法由于未考虑元素间的相关性,估计精度略低。     

基于马尔科夫网视频图像目标检测跟踪方法研究

研究了马尔科夫网的概念、方法,分析它在空间数据挖掘中的作用与意义,并以视频图像为例广泛研究以多种粒度(节点数)建立视频图像间的马尔科夫网,通过网络结构分析检测视频图像中的目标差异。研究表明马尔科夫网可以很好地揭示数据间的抽象近邻关系,并且这种网络自身就具有表达知识的意义。     

Probabilistic Distribution of the Maximum Wave Heigh

A new method of treating maximum wave height as a random variable in reliability analysis of breakwater caissons is proposed. The maximum wave height is expressed as the significant wave height multiplied by the so-called wave height ratio. The proposed wave height ratio is a type of transfer function from the significant wave height to the maximum wave height. Under the condition of a breaking wave, the ratio is intrinsically nonlinear. Therefore, the probability density function for the variable cannot be easily defined. In this study, however, it can be derived from the relationship between the maximum and significant waves in a nonbreaking environment. Some examples are shown to validate the derived probability density function for the wave ratio parameter. By introducing the wave height ratio into reliability analysis of caisson breakwater, the maximum wave height can be used as an independent and primary random variable, which means that the risk of caisson failure during its lifetime can be evaluated realistically.     

曹妃甸工业区最大风速资料重建及检验

将曹妃甸工业区2007—2008年自动气象站的最大风资料和唐海、乐亭、滦南气象站1972—2008年最大风资料进行u,v分量分解,分别建立最大风u、v分量的回归模型,然后利用唐海、乐亭、滦南气象站1972—2006年最大风资料,对曹妃甸1972—2006年最大风资料进行重建。对曹妃甸的实测资料和重建资料分别与唐海同时段实测资料进行对比分析,分析结果表明：唐海与曹妃甸之间最大风速的相关关系是比较稳定的;风向存在一些差异,风速较小时,两站风向偏差较大,风速较大时,两站风向偏差较小。曹妃甸与唐海实测资料风向在同·方位的次数,春季占28.3%,夏季占31.5%,秋季占24.7%,冬季占33,1%;曹妃甸重建资料与唐海实测资料的风向在同一方位的次数,春季与46%,夏季占29,4%,秋季占42,7%,冬季占54%。为了考察重建资料的合理性,在不同月份选取120个大风个例,分析重建资料与天气系统的对应关系,120个个例中,有5个无明显的天气系统配合,其他均有天气系统配合。重建后的最大风速具有明显的分布特征,经检验,曹妃甸日最大风速较好地服从Gamma分布。该资料序列可以用于大风灾害的分析与评估。     

基于MKLD准则的PSOPF算法设计及其应用

针对标准粒子滤波算法中存在的粒子权值退化和计算量大的缺陷,提出了基于MKLD准则的粒子群优化粒子滤波算法。该方法将粒子群优化算法嵌入到粒子滤波算法的重要性采样过程中,对采样过程进行了优化,提高了粒子集的优良性的同时保证了粒子滤波状态估计的性能。同时,为了降低计算量,算法设计时基于MKLD准则自适应地选择粒子群优化算法所...     

闽南沿海暴雨特征及可能最大降水估算

根据福建南部沿海气象站和水文站1961—2007年降水资料,分析其暴雨特征,应用概率论方法和水文气象法,推求福建南部沿海24 h可能最大降水。结果显示：①福建南部沿海的暴雨主要集中于春夏两季,冷暖空气交绥的锋面暴雨以及台风等热带天气系统所致的暴雨是福建南部沿海最主要的两种暴雨类型。即使同处暴雨一致区,暴雨强度及出现的区域也有一定的偶然性。②采用皮尔逊-Ⅲ型法计算不同重现期24 h的最大降水量时,如果不考虑降水的随机性,不做暴雨一致区的特大暴雨移置和特大值处理,将会影响概率论法计算结果的合理性。③暴雨模式的拟定是整个工作的基础,所选暴雨模式中地形对降水有显著的增幅作用,可认为是高效率暴雨模式,故选择水汽放大法计算,与概率论方法比较,计算结果是合理的。     

震级离散下的震级频度关系

运用最大熵原理,研究震级离散条件下震级频度关系,得到震级离散条件下震级概率分布函数,结果表明:(1)震级大于等于某一震级的地震次数应通过离散求和的方式得到,而不应通过积分的方式得到;(2)震级上限取为∞的情况下,古登堡意义和里克特意义两种震级频度关系式的b值相等;震级上限有限的情况下,里克特意义震级频度关系式可能不是直...     

山东地区b值的统计分析

利用山东省内及其邻近海域(34°～39°N,114°～125°E),1996年1月至2009年5月的地震资料,通过最小二乘法及极大似然法对山东地区近年来的b值进行了求解及分析,给出了本区b值的计算结果,讨论了两种方法得到结果的差异,并对近年来6值时序变化的一些特点及其所反映的问题进行了讨论.     

Architecture and formation of transgressive–regressive cycles in marginal marine strata of the John Henry Member,Straight Cliffs Formation,Upper Cretaceous of Southern Utah,USA

Marginal marine deposits of the John Henry Member, Upper Cretaceous Straight Cliffs Formation, were deposited within a moderately high accommodation and high sediment supply setting that facilitated preservation of both transgressive and regressive marginal marine deposits. Complete transgressive–regressive cycles, comprising barrier island lagoonal transgressive deposits interfingered with regressive shoreface facies, are distinguished based on their internal facies architecture and bounding surfaces. Two main types of boundaries occur between the transgressive and regressive portions of each cycle: (i) surfaces that record the maximum regression and onset of transgression (bounding surface A); and (ii) surfaces that place deeper facies on top of shallower facies (bounding surface B). The base of a transgressive facies (bounding surface A) is defined by a process change from wave‐dominated to tide‐dominated facies, or a coaly/shelly interval indicating a shift from a regressive to a transgressive regime. The surface recording such a process change can be erosional or non‐erosive and conformable. A shift to deeper facies occurs at the base of regressive shoreface deposits along both flooding surfaces and wave ravinement surfaces (bounding surface B). These two main bounding surfaces and their subtypes generate three distinct transgressive – regressive cycle architectures: (i) tabular, shoaling‐upward marine parasequences that are bounded by flooding surfaces; (ii) transgressive and regressive unit wedges that thin basinward and landward, respectively; and (iii) tabular, transgressive lagoonal shales with intervening regressive coaly intervals. The preservation of transgressive facies under moderately high accommodation and sediment supply conditions greatly affects stratigraphic architecture of transgressive–regressive cycles. Acknowledging variation in transgressive–regressive cycles, and recognizing transgressive successions that correlate to flooding surfaces basinward, are both critical to achieving an accurate sequence stratigraphic interpretation of high‐frequency cycles.     

Experimental Investigation of the Decay from A Ship’s Propeller

In the present study,an experimental investigation of the decay of the maximum velocity and its turbulent characteristics behind a ship propeller,in "bollard pull" condition(zero speed of advance),is reported.Velocity measurements were performed in laboratory by use of a Laser Doppler Anemometry(LDA) measurement system.Earlier researchers described that the maximum axial velocity is constant at the initial stage of a ship’s propeller jet(Fuehrer and Rmisch,1977;Blaauw and van de Kaa,1978;Berger et al.,1981;Verhey,1983) as reported in a pure water jet(Albertson et al.,1950;Lee et al.,2002;Dai,2005),but a number of researchers disagreed with the constant velocity assumption.The present study found that the maximum axial velocity decays in the zone of flow establishment and the zone of established flow with different rates.The investigation provides an insight into the decays of both the maximum velocity and the maximum turbulent fluctuation in axial,tangential and radial components and the decay of the maximum turbulent kinetic energy.Empirical equations are proposed to allow coastal engineers to estimate the jet characteristics from a ship’s propeller.